It consists of numerous small projec- involved 100 mg desyrel fast delivery, followed by buccal mucosa and tongue cheap 100mg desyrel. The tumor has a white or grayish first buy discount desyrel 100mg on-line, which is referred to as the "sharp" variety, color and varies in size from several millimeters to consists of long, narrow, and white verrucous 1 or 2 cm in diameter. The second, which is referred to as the the palate and the tongue and less often on the "blunt" variety, consists of white verrucous pro- buccal mucosa, gingiva, and lips. The differential diagnosis includes verruca vul- Verrucous hyperplasia is frequently associated garis, condyloma acuminatum, verruciform xan- with leukoplakia (53%), as well as verrucous car- thoma, sialadenoma papilliferum, verrucous car- cinoma (29%), and rarely squamous cell car- cinoma, and focal dermal hypoplasia syndrome. The differential diagnosis should include pro- liferating verrucous leukoplakia, verrucous car- Treatment is surgical excision. Benign Tumors Keratoacanthoma The differential diagnosis includes giant cell fi- broma, lipoma, myxoma, peripheral ossifying fi- Keratoacanthoma is a fairly common benign skin broma, neurofibroma, schwannoma, fibrous his- tumor that probably arises from the hair follicles. Clinically, it appears as a painless well-circumscribed dome or bud-shaped tumor of Treatment is surgical excision. The tumor begins as a small nodule that grows rapidly and, within 4 to 8 weeks, reaches its Giant Cell Fibroma full size. For a period of 1 to 2 months, it persists without change, and then it may undergo spon- Giant cell fibroma is a fibrous lesion of the oral taneous regression over the next 5 to 10 weeks. The differential diagnosis should include basal and The differential diagnosis should include fibroma, squamous cell carcinomas and warty dys- neurofibroma, papilloma, peripheral ossifying fi- keratoma. Fibroma Fibroma is the most common benign tumor of the oral cavity and originates from the connective tissue. It is believed that the true fibroma is very rare and that most cases represent fibrous hyper- plasia caused by chronic irritation. Clinically, the fibroma is a well-defined, firm, sessile or pedunculated tumor with a smooth surface of normal epithelium (Fig. It appears as an asymptomatic, single lesion usually under 1 cm in diameter, although in rare cases it may reach several centimeters. Benign Tumors Peripheral Ossifying Fibroma Soft-Tissue Osteoma Peripheral ossifying fibroma, or peripheral odon- Osteomas are benign tumors that represent a pro- togenic fibroma, is a benign tumor that is located liferation of mature cancellous or compact bone. Osteomas are more common unknown, although it is believed that it derives between 30 and 50 years of age and have a pre- from the periodontal ligament. Clinically, it is a drome, oral soft tissue osteomas are, however, well-defined firm tumor, sessile or pedunculated, rare. Lesions have been described in the palate, covered by smooth normal epithelium (Figs. Usually the surface is ulcerated due to Clinically, soft-tissue osteoma appears as a mechanical trauma. The size varies from a few well-defined, asymptomatic hard tumor covered millimeters to 1 to 2 cm, and more than 50% of by thin and smooth normal epithelium (Fig. The differential diagnosis of soft tissue osteoma The differential diagnosis should include fibroma, includes torus palatinus, exostoses, and fibroma. The diagnosis is established by loma, pyogenic granuloma, pregnancy granuloma, histopathologic examination. Benign Tumors Lipoma Neurofibroma Lipoma is a benign tumor of adipose tissue rela- Neurofibroma is a benign overgrowth of nerve tively rare in the oral cavity. It is more common tissue origin (Schwann cells, perineural cells, between 40 and 60 years of age and is usually endoneurium). It is relatively rare in the mouth located on the buccal mucosa, tongue, mucobuc- and may occur as a solitary or as multiple lesions cal fold, floor of the mouth, lips, and gingiva. Clinically, it usually tumor, pedunculated or sessile, varying in size appears as a painless well-defined pedunculated from a few millimeters to several centimeters of firm tumor, covered by normal epithelium (Fig. Neurofibromas vary in size from several epithelium is thin, with visible blood vessels. The lesion is soft on palpation and occasionally fluctuant and usually located on the buccal mucosa and palate, may be misdiagnosed as a cyst, especially when it followed by the alveolar ridge, floor of the mouth, is located in the deeper submucosal tissues. The differential diagnosis includes myxoma, fi- The differential diagnosis includes schwannoma, broma, mucocele, and small dermoid cyst. It is extremely rare in the oral mucosa and most of the lesions represent myxoid degeneration of the connective tissue and not a true neoplasm. Clinically, the myxoma is a well-defined mobile tumor covered by normal epithelium and soft on palpation (Fig. It may appear at any age and is most frequent on the buccal mucosa, floor of the mouth, and palate. The differential diagnosis includes fibroma, lipoma, mucoceles, and focal mucinosis. Immunohistochemi- cal markers are useful to distinguish nerve sheath myxomas from other oral myxoid lesions. Benign Tumors Schwannoma Leiomyoma Schwannoma, or neurilemoma, is a rare benign Leiomyoma is a rare benign tumor derived from tumor derived from the Schwann cells of the nerve smooth muscles. Clinically, it appears as a solitary well- smooth muscles of blood vessel walls and from the circumscribed firm and sessile nodule, usually circumvallate papillae of the tongue. It is oma affects both sexes equally and usually persons painless, fairly firm on palpation, and varies in more than 30 years of age. The Schwannoma may occur at any age and is a slow-growing, painless, firm, and well-defined most commonly located on the tongue, followed tumor with normal or reddish color (Fig. Most frequently, it occurs on the tongue, followed by the buccal mucosa, palate, and lower lip. The differential diagnosis includes neurofibroma, fibroma, granular cell tumor, lipoma, leiomyoma, The differential diagnosis includes other benign traumatic neuroma, pleomorphic adenoma, and tumors of connective tissue origin and blood ves- other salivary gland tumors. Traumatic Neuroma Traumatic neuroma or amputation neuroma is not a true neoplasm, but a hyperplasia of nerve fibers and surrounding tissues, after injury or transec- tion of a nerve. Clinically, it appears as a small, usually movable tumor or nodule covered by nor- mal mucosa. Traumatic neuroma is charac- terized by pain, particularly on palpation, and is often located close to the mental foramen, on the alveolar mucosa of edentulous areas, the lips, and the tongue (Fig. The differential diagnosis includes neurofibroma, schwannoma, foreign-body reaction, and salivary gland tumor. Benign Tumors Verruciform Xanthoma Benign Fibrous Histiocytoma Verruciform xanthoma is a rare benign tumor of Benign fibrous histiocytoma is a cellular tumor the oral cavity, of unknown cause and his- primarily composed of histiocytes and fibroblasts togenesis, first described by Shafer in 1971. It represents a outstanding microscopic feature is the presence of localized reactive lesion rather than a true neo- large xanthoma or foam cells in the connective plasm. The tumor occurs more often on the skin of tissue papillae, which do not extend beyond the the neck region and very rarely on the oral epithelial rete peg extensions. Both sexes are affected, between 8 and between the 5th and 7th decades of life and seems 70 years old, and the size of the tumor ranges to have a slight predilection for females (female: between 0. Less cally, it appears as a painless, mobile, and firm often, it may be seen on the mucobuccal fold, tumor, covered by normal epithelium, which may palate, floor of the mouth, tongue, lips, and buc- be ulcerated (Fig. Clinically, it appears as a sessile, The differential diagnosis includes fibroma, slightly elevated, and well-defined lesion. It has a neurofibroma, schwannoma, lipoma, and granular cauliflower-like surface with normal or red-yel- cell tumor. The diagnosis is established by The differential diagnosis includes papilloma, ver- histopathologic criteria. Recent evidence indicates that the origin of the tumor may be the perineural Schwann cells rather than muscles. Clinically, it is a small, firm, well-defined asymptomatic nodule with whitish or normal color, which may be slightly elevated (Fig. In the oral cavity it is usually located on the dorsum and the lateral border of the tongue. The differential diagnosis should include rhab- domyoma, fibroma, neurofibroma, schwannoma, traumatic neuroma, congenital epulis of the new- born, and other benign mesenchymal tumors. This concept is sup- Klippel-Trenaunay-Weber syndrome, and the ported by the frequent presence of hemangiomas Rendu-Osler-Weber syndrome. On histologic criteria, two Laboratory test useful for the diagnosis is his- main types of hemangiomas are recognized: capil- topathologic examination. The biopsy has to be lary hemangioma, which consists of numerous taken very cautiously because of the danger of small capillaries and clinically appears as a flat red hemorrhage.
If dengue occurs near possible jungle foci of yellow fever cheap desyrel 100 mg overnight delivery, immunize the population against yellow fever because the urban vector for the two diseases is the same buy desyrel 100mg free shipping. Acetylsalicylic acid (aspirin) is contraindicated because of its hemorrhagic potential cheap 100mg desyrel otc. Epidemic measures: 1) Search for and destroy Aedes mosquitoes in sites of human habitation, and eliminate or apply larvicide to all potential Ae. Disaster implications: Epidemics can be extensive and affect a high percentage of the population. International measures: Enforce international agreements designed to prevent the spread of Ae. Identiﬁcation—A severe mosquito-transmitted viral illness en- demic in much of southern and southeastern Asia, the Paciﬁc and Latin America, characterized by increased vascular permeability, hypovolaemia and abnormal blood clotting mechanisms. Prompt oral or intravenous ﬂuid therapy may reduce hematocrit rise and require alternate observa- tions to document increased plasma leakage. Coincident with defervescence and decreasing platelet count, the pa- tient’s condition suddenly worsens in severe cases, with marked weak- ness, restlessness, facial pallor and often diaphoresis, severe abdominal pain and circumoral cyanosis. In severe cases, ﬁndings include accumulation of ﬂuids in serosal cavities, low serum albumin, elevated transaminases, a prolonged prothrombin time and low levels of C3 complement protein. Case-fatality rates in mistreated shock have been as high as 40%–50%; with good physiological ﬂuid replacement therapy, rates should be 1%–2%. IgM antibody, indicating a current or recent ﬂavivirus infection, is usually detectable by day 6–7 after onset of illness. Viruses can be isolated from blood during the acute febrile stage of illness by inoculation to mosquitoes or cell cultures. In out- breaks in the Americas, the disease is observed in all age groups although two-thirds of fatalities occur among children. Reservoir, Mode of transmission, Incubation period and Period of communicability—See Dengue fever. Susceptibility—The best-described risk factor is the circulation of heterologous dengue antibody, acquired passively in infants or actively from an earlier infection. Such antibodies may enhance infection of mononuclear phagocytes through the formation of infectious immune complexes. Geographic origin of dengue strain, age, gender and human genetic susceptibility are also important risk factors. Control of patient, contacts and immediate environment: 1), 2), 3), 4), 5) and 6) Report to local health authority, Isolation, Concurrent disinfection, Quarantine, Immuniza- tion of contacts and Investigation of contacts and source of infection: See Dengue fever. The rate of ﬂuid administration must be judged by estimates of loss, usually through serial microhematocrit urine output and clinical monitoring. Blood transfusions are indicated for massive bleeding or in cases with unstable signs or a true fall in hematocrit. The use of heparin to manage clinically signiﬁ- cant hemorrhage occurring in the presence of well-docu- mented disseminated intravascular coagulation is high-risk and of no proven beneﬁt. Fresh plasma, ﬁbrinogen and platelet concentrate may be used to treat severe hemor- rhage. Epidemic measures, Disaster implications and International measures: See Dengue fever. Various genera and species of fungi known collectively as the dermatophytes are causative agents. Identiﬁcation—A fungal disease that begins as a small area of erythema and/or scaling and spreads peripherally, leaving scaly patches of temporary baldness. It is characterized by a mousy smell and by the formation of small, yellowish, cuplike crusts (scutulae) that amalgamate to form a pale or yellow visible mat on the scalp surface. Affected hairs do not break off but become grey and lustreless, eventually falling out and leaving baldness that may be permanent. Tinea capitis is easily distinguished from black piedra, a fungus infection of the hair occurring in tropical areas of South America, southeastern Asia and Africa. This is characterized by black, hard “gritty” nodules on hair shafts, caused by Piedraia hortai. Species and genus identiﬁcation is important for epidemiological, prognostic and therapeutic reasons. Mode of transmission—Direct skin-to-skin or indirect contact, especially from the backs of seats, barber clippers, toilet articles (combs, hairbrushes), clothing and hats that are contaminated with hair from infected people or animals. Period of communicability—Viable fungus and infective arthros- pores may persist on contaminated materials for long periods. Preventive measures: 1) Educate the public, especially parents, to the danger of acquiring infection from infected individuals as well as from dogs, cats and other animals. Control of patient, contacts and the immediate environment: 1) Report to local health authority: Obligatory report of epidem- ics in some countries; no individual case report, Class 4 (see Reporting). In severe cases, wash scalp daily and cover hair with a cap, which should be boiled after use. Systemic antibacterial agents are useful if lesions become secondarily infected by bacteria; in the case of kerions, also use an antiseptic cream and remove scaly crusts from the scalp by gentle soaking. Examine regularly and take cultures; when cultures become negative, complete recovery may be assumed. Epidemic measures: In school or other institutional epidem- ics, educate children and parents as to mode of spread, preven- tion and personal hygiene. Enlist services of physi- cians and nurses for diagnosis; carry out follow-up surveys. Identiﬁcation—A fungal disease of the skin other than of the scalp, bearded areas and feet, characteristically appearing as ﬂat, spreading, ring-shaped or circular lesion with a characteristic raised edge around all or part of the lesion. This periphery is usually reddish, vesicular or pustular and may be dry and scaly or moist and crusted. As the lesion progresses peripherally, the central area often clears, leaving apparently normal skin. Differentiation from inguinal candidiasis, often distinguished by the pres- ence of “satellite” pustules outside the lesion margins, is necessary because treatment differs. Infectious agents—Most species of Microsporum and Trichophyton; also Epidermophyton ﬂoccosum. Mode of transmission—Direct or indirect contact with skin and scalp lesions of infected people, lesions of animals; contaminated ﬂoors, shower stalls, benches and similar articles. Period of communicability—As long as lesions are present and viable fungus persists on contaminated materials. Susceptibility—Susceptibility is widespread, aggravated by friction and excessive perspiration in axillary and inguinal regions, and when environmental temperatures and humidity are high. Preventive measures: Launder towels and clothing with hot water and/or fungicidal agent; general cleanliness in public showers and dressing rooms (repeated washing of benches; frequent hosing and rapid draining of shower rooms). A fungi- cidal agent such as cresol should be used to disinfect benches and ﬂoors. Control of patient, contacts and the immediate environment: 1) Report to local health authority: Obligatory report of epidem- ics in some countries; no individual case report, Class 4 (see Reporting). Epidemic measures: Educate children and parents about the infection, its mode of spread and the need to maintain good personal hygiene. Identiﬁcation—This fungal disease presents with characteristic scaling or cracking of the skin, especially between the toes (interdigital), diffuse scaling over the sole of the foot (dry type) or blisters containing a thin watery ﬂuid; commonly called athlete foot. In severe cases, vesicular lesions appear on various parts of the body, especially the hands; these dermatophytids do not contain the fungus but are an allergic reaction to fungus products. Presumptive diagnosis is veriﬁed by microscopic examination of potas- sium hydroxide-or calcoﬂuor white-treated scrapings from lesions that reveal septate branching ﬁlaments. Note that bacteria, including Gram- negative organisms and coryneforms, as well as Candida and Scytalidium species, may produce similar lesions. They are also common in industrial workers, schoolchildren, athletes and military personnel who share shower or bathing facilities. Period of communicability—As long as lesions are present and viable spores persist on contaminated materials. Educate the public to maintain strict personal hygiene; take special care in drying between toes after bathing; regularly use a dusting powder or cream containing an effective antifungal on the feet and partic- ularly between the toes. Control of patient, contacts and the immediate environment: 1) Report to local health authority: Obligatory report of epidem- ics in some countries; no individual case report, Class 4 (see Reporting). Oral terbinaﬁne, or itraconazole may be indicated in severe, extensive or protracted disease; griseofulvin, although less active, is an alternative. Epidemic measures: Thoroughly clean and wash ﬂoors of showers and similar sources of infection; disinfect with a fungi- cidal agent such as cresol.
Geo-physically remote and socio-economically backward population remains underserved buy desyrel 100 mg with amex. Inadequate service provision for Eye Diseases other than cataract Cataract intervention has been given the highest priority attention under the National Programme for Control of Blindness and the problem of Corneal Blindness desyrel 100mg overnight delivery, Glaucoma and Diabetic Retinopathy have not been adequately addressed order 100mg desyrel amex. Similarly Pediatric Ophthalmology and low vision have also received a lower priority. Lack of Public Awareness Rural, illiterate and under privileged population are not fully aware about various interventions that are available to restore vision of the blind. Integration with primary health care is also limited and therefore rural health workers are not motivating potential beneficiaries. For the first time in the country, a Rapid Assessment of Avoidable Blindness was undertaken. This methodology improves upon the methodology used in Rapid Assessment and allows causes of blindness to be established. This is achieved by coupling an eye examination by an ophthalmologist to the methodology used in rapid assessments. Therefore, data can be comparable to both the rapid assessment as well as the detailed surveys conducted earlier. It was observed that overall, the prevalence of low vision, economic blindness and social blindness had decreased in the districts covered compared to the earlier surveys. Lowest prevalence of all blindness (social + economic) was seen in Solan (Himachal Pradesh), Bhatinda (Punjab) and Palakkad (Kerala). Pooling data of all districts together the prevalence of blindness as defined by the National Program for Control of Blindness has shown a reduction of 6% in overall prevalence of blindness above the age of 50 years. This reduction is significant as there is an increasing life expectancy in India which translates into more and more people living beyond 50 years of age. Since a significant proportion of blindness in India is age related, any reduction above the age of 50 years is a direct gain from the strategies adopted by the National Program in the country. It is difficult to state whether this is due to a true rate of higher incidence among females or 76 because of lack of access to services. Though a larger number of surgeries were reported of women, this would be expected as 55% of the respondents were female. The prevalence of blindness increased with age, with those above 70 years having a 16 times higher risk of being blind compared to those aged 50-54 years. Cataract surgical coverage showed a significant increase compared to the previous surveys with 82. For the first time this is being used in the country as it was felt that this would act as a baseline for future surveys as more and more people would get operated before they reach a stage of vision < 3/60. The survey showed that the gains in Southern States (Andhra Pradesh, Kerala and Tamilnadu) and in high performing States like Gujarat continued to improve over the years. Performance in the States of Orissa (Ganjam district) and West Bengal (Malda district) needs to be augmented so that the gains of the technological revolution in eye care can be effectively harnessed across the country. Cataract remains the single largest cause of blindness, low vision and one eye blindness in India if the data of the 16 districts are pooled together. Results indicate that the country should continue to prioritize cataract surgical services and their augmentation. The support to other blinding conditions should not be at the cost of cataract as any slackening may prove catastrophic in the long run. Lack of awareness and affordability still continue to be barriers to the uptake of cataract surgery in many parts of the country and efforts need to be made to surmount these barriers so that no person needlessly remains blind because of lack of knowledge or the lack of access due to financial constraints. The country seems headed in the right direction and attention to problem regions on a priority basis will provide a further impetus to blindness control efforts in India. The grant would cover activities such as construction/repair of existing buildings, purchase of equipment, provision of infrastructure such as water- tanks and toilet facilities, purchase of cots and equipments. It did not cover expenses in the nature of salaries and recurring expenses towards th running the mental hospitals and cost towards drugs and consumables. During the 11 plan, 23 State run Mental Hospitals were funded for modernization of mental hospitals. Upgradation of Psychiatric Wings of Medical Colleges/General Hospitals - Every medical college should ideally have a Department of Psychiatry with minimum of three faculty members and inpatient facilities of about 30 beds as per the norms laid down by the Medical Council of India etc. Out of the existing medical colleges in the country, approximately one third do not have adequate psychiatric services. Centres of Excellence (Scheme A) - Under Manpower Development Component at least 11 th Centres of Excellence in mental health were to be established in the 11 plan period by upgrading existing mental health institutions/medical colleges. The support includes capital work (academic block, library, hostel, lab, supportive departments, lecture theatres etc. Current status: - 10 centres have been selected and grant has been released for establishment, 1 centre is in pipeline of submitting state commitment. The support would involve physical work for establishing/improving department in specialities of mental health (Psychiatry, Clinical Psychology, Psychiatric Social Work, and Psychiatric Nursing), equipments, tools and basic infrastructure, support for engaging required/deficient faculty etc. Current status: Psychiatry – 7 (established) +1 (in pipeline) = 8 Clinical Psychology – 5 (established) + 5 (in pipeline) = 10 Psychiatric Social Work – 3 (established) + 5 (in pipeline) = 8 Psychiatric Nursing – 5 (established) + 6 (in pipeline) = 11 Gap Analysis No. Resurvey after every 5 years to assess the extent of Iodine Deficiency Disorders and the Impact of iodated salt. On the recommendations of Central Council of Health in 1984, the Government took a policy decision to iodated the entire edible salt in the country by 1992. The Central Government is implementing ban notification on the sale 80 of non-iodated salt for direct human consumption under Prevention of Food Adulteration Act, 1954 with effect from 17th May, 2006. The annual production and supply of iodated salt in our country is 55 lakh metric tones per annum during 2009-10. The consumption of iodated salt at the community level was evaluated by the National Family Health Survey, 2005-06 and indicated the consumption of adequately iodated salt at the community level was about 51% while salt having nil and inadequate iodine was about 49%. It may be pointed out that in both the studies the consumption of adequately iodated salt is the rural population is far below in comparison to urban population. The specific provisions under this Act include: a) Ban on smoking in public places. Currently the programme is under implementation in 21 out of 35 States/Union territories in the country covering 42 districts. Public awareness/mass media campaigns for awareness building and behavioral change. Mainstreaming the program components as a part of the health delivery mechanism under the National Rural Health Mission framework. Mainstream Research & Training on alternate crops and livelihoods in collaboration with other nodal Ministries. State level Dedicated tobacco control cells for effective implementation and monitoring of anti tobacco initiatives. Some of the demand reduction strategies include price and tax measures & non price measures (statutory warnings, comprehensive ban on advertisement, promotion and sponsorship, tobacco product regulation etc). The supply reduction strategies include combating 82 illicit trade, providing alternative livelihood to tobacco farmers and workers & regulating sale to / by minors. Compliance with provisions of the Act is still a major challenge as the personnel in different parts of the State and District Administration lack sensitisation to the significance of this programme. Although 15 states have established challaning mechanism for enforcement of smoke-free rules, out of which only 11 states collected fines for violations of ban on smoking in public places. Similarly steering committee for implementation of section-5 (ban on Tobacco advertisements, promotion and sponsorship) has been constituted in 21 states but only 3 states collected fines for the violation of this provision. Similarly enforcement of ban on sale of tobacco products to minors and ban on sale of tobacco products within 100 yards also remains largely ineffective in many states. Setting up of tobacco cessation facilities at district level is also a big challenge. Less than half of the states under the programme have established tobacco cessation facilities at district level. National Deafness Control Program (2006-07) The programme has been expanded to 176 districts of 16 States and 3 U. Progress made by the programme in different components of the programme is summarized below: (a) Training: Trainings for all levels of manpower have been planned in the programme. In the expansion phase, the responsibility of training was transferred to the states, for which funds were provided to the state health societies. In the expansion phase, the states of Uttarakhand, Karnataka and Gujarat initiated the training upto level 4 (i. Beyond level 4 only the state of Assam, Uttarakhand and Andhra Pradesh are being organizing trainings in the districts. Regular screening camps have been conducted by the states of Tamil Nadu, Karnataka, Chandigarh, Sikkim and Andhra Pradesh.
As a result of accidental changes in its environment purchase desyrel 100 mg overnight delivery, a cell can undergo changes in its genetic material generic 100 mg desyrel amex. Bacteria have been found that can live in temperatures above the boiling point and in cold that would freeze your blood discount desyrel 100 mg otc. Bacteria are prokaryotes (Kingdom Monera), which means that they have no true nucleus. Most bacteria lack or have very few internal membranes, which means that they don’t have some kinds of organelles (like mitochondria or chloroplasts). Most bacteria are benign (benign = good, friendly, kind) or beneficial, and only a few are “bad guys” or pathogens. There are some bacteria relatives that can do photosynthesis--they don’t have chloroplasts, but their chlorophyll and other needed chemicals are built into their cell membranes. These organisms are called Cyanobacteria (cyano = blue, dark blue) or bluegreen algae, although they’re not really algae (real algae are in Kingdom Protista). Like us, some kinds of bacteria need and do best in O , while others are poisoned or killed by it. All other life forms are Eukaryotes (you-carry-oats), creatures whose cells have nuclei. Many believe that more complex cells developed as once free-living bacteria took up residence in other cells, eventually becoming the organelles in modern complex cells. There are thousands of species of bacteria, but all of them are basically one of three different shapes. Some bacterial cells exist as individuals while others cluster together to form pairs, chains, squares or other groupings. A single teaspoon of topsoil contains more than a billion (1,000,000,000) bacteria. Peptidoglycan Most bacteria secrete a covering for themselves which we call a cell wall. However, bacterial cell walls are a totally different thing than the cell walls we talk about plants having. Bacterial cell walls are made mostly of a chemical called peptidoglycan (made of polypeptides bonded to modified sugars), but the amount and location of the peptidoglycan are different in the two possible types of cell walls, depending on the species of bacterium. Some antibiotics, like penicillin, inhibit the formation of the chemical cross linkages needed to make peptidoglycan. These antibiotics don’t kill the bacteria outright, just stop them from being able to make more cell wall so they can grow. That’s why antibiotics must typically be taken for ten days until the bacteria, unable to grow, die of “old age”. If a person stops taking the antibiotic sooner, any living bacteria could start making peptidoglycan, grow, and reproduce. Thus it is important, before beginning antibiotic treatment, to determine with which of the two types of bacteria one is dealing. Hans Christian Gram, a Danish physician, invented a staining process to tell these two types of bacteria apart, and in his honor, this process is called Gram stain. In this process, the amount of peptidoglycan in the cell walls of the bacteria under study will determine how those bacteria absorb the dyes with which they are stained; thus, bacterial cells can be Gram or Gram. Gram bacteria have simpler cell walls with lots of+ - + peptidoglycan, and stain a dark purple color. Gram bacteria have more complex cell walls- with less peptidoglycan, thus absorb less of the purple dye used and stain a pinkish color instead. Also, Gram bacteria often incorporate toxic chemicals into their cell walls, and thus tend- to cause worse reactions in our bodies. Because Gram bacteria have less peptidoglycan,- antibiotics like penicillin are less effective against them. As we have discussed before, taking antibiotics that don’t work can be bad for you, thus a good doctor should always have a culture done before prescribing antibiotics to make sure the person is getting something that will help. Pseudomonas aeruginosa is a strictly aerobic, oxidase positive, gram-negative nonfermentative bacterium. The Gram-stain appearance is not particularly characteristic, although rods are somewhat thinner than those seen for the enteric-like bacteria. Mucoid strains that produce an extracellular polysaccharide are frequently isolated from patients with cystic fibrosis and this capsular material can be seen in the photo. Structure of a Eucaryotic Cell Cell Membrane The cell is enclosed and held intact by the cell membrane/plasma membrane/cytoplasmic membrane. These large molecules permit the passage of nutrients, waste products, and secretions across the cellular membrane. Nucleus The Nucleus unifies, controls, and integrates the function of the entire cell. The nucleus is enclosed in the nuclear membrane and contains chromosomes; the number and composition of chromosomes and the number of genes on each chromosome are characteristic of each species. It is composed of a semifluid gelatinous nutrient matrix and cytoplasmic organelles including endoplasmic reticulum, ribosomes, Golgi complex, mitochondria, centrioles, microtubules, lysosomes and vacoules. It is different from the simple cell wall of plant cells and is made up of macromolecular polymer-peptidoglycan (protein and polysaccharide chain). Cilia and Flagella Some eukaryotic cells possess relatively long and thin structures called flagella. Cilia are also organs of locomotion but are shorter and more numerous Structure of a Prokaryotic Cell All bacteria are prokaryotes and are simple cells. Chromosome The chromosome of a prokaryotic cell is not surrounded by a nuclear membrane, it has no definite shape and no protein material associated with it. Cytoplasm Cytoplasm is a semi-liquid that surrounds the chromosome and is contained within the plasma membrane. Located within the cytoplasm are several ribosomes, which are the sites of protein synthesis. Cytoplasmic granules occur in certain species of bacteria which can be specifically stained and used to identify the bacteria. Cell Membrane The Cell Membrane is similar to that of the eukaryotic cell membrane. It is selectively permeable and controls the substances entering or leaving the cell. When highly organized and firmly attached to the cell wall, this layer is called a capsule; or if it is not highly organized and not firmly attached, a slime layer. Capsules consist of complex sugars or polysaccharides combined with lipids and proteins. The composition of the capsule is useful in differentiating between different types of bacteria. Capsules are usually detected by negative staining, where the bacterial cell and the background become stained but the capsule remains unstained. Encapsulated bacteria produce colonies on nutrient agar that are smooth, mucoid and glistening, whereas the noncapsulated bacteria produce rough and dry colonies. Capsules enable the bacterial species to attach to mucus membranes and protect the bacteria from phagocytosis. Flagellated bacteria are said to be motile while non-flagellated bacteria are generally non-motile. The number and arrangement of flagella are species specific and can be used to classify bacteria. Pili or Fimbriae Pili or Fimbriae are thin hair-like structures observed on gram negative bacteria. They are also used to transfer genetic material from one bacteria cell to another. Spores Some bacteria are capable of forming spores (also called endospore) as a means of survival under adverse conditions. During sporulation the genetic material is enclosed in several protein coats that are resistant to heat, drying and most chemicals. When the dried spore lands on a nutrient rich surface, it forms a new vegetative cell.
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