By N. Yussuf. Carleton College.

In most countries buy 100mg luvox free shipping anxiety quotes images, this group of cases represented a small proportion of total cases luvox 100mg fast delivery anxiety symptoms of; 35 however buy 100mg luvox otc anxiety tattoo, in eight countries (Australia, Fiji, Guam, New Caledonia, Puerto Rico, Qatar, Solomon Islands and the United States) and one region in Spain (Barcelona), this represented the majority or the only group reported. This section of the report covers the latest data from countries reporting from 2002 to 2007. The median number of cases tested per setting in survey settings was 547, and ranged from 101 new cases in Mimika district in the Papua province of Indonesia to 1619 new cases in Viet Nam. The median number of new cases tested among the settings conducting surveillance was 485, and ranged from 7 cases in Iceland to 3379 in the United Kingdom. Thirteen settings reported prevalence of resistance to any drug of 30% or higher (Figure 1). Figure 1: Countries or settings with prevalence of any resistance higher than 30% among new cases, 2002–2007. Baku City, Azerbaijan Tashkent, Uzbekistan Georgia Republic of Moldova Donetsk Oblast, Ukraine Heilongjiang Province, China Armenia Latvia Tomsk Oblast, Russian Fed Inner Mongolia Auton. Baku City, Azerbaijan Republic of Moldova Donetsk Oblast, Ukraine Tomsk Oblast, Russian Fed Tashkent, Uzbekistan Estonia Mary El Oblast, Russian Fed Latvia Lithuania Armenia Orel Oblast, Russian Fed Inner Mongolia Auton. Sixteen settings reported a prevalence of isoniazid resistance 15% or higher among new cases (Figure 3). Tashkent, Uzbekistan Baku City, Azerbaijan Republic of Moldova Donetsk Oblast, Ukraine Latvia Armenia Tomsk Oblast, Russian Fed Mary El Oblast, Russian Fed Georgia Estonia Inner Mongolia Auton. The number of cases tested in settings conducting routine surveillance ranged from 1 (Iceland) to 522 (Poland), with a median of 58 cases per setting. The number of cases tested in settings conducting surveys ranged from 16 (Lebanon) to 1047 (Gujarat State, India) and 2054 cases in the Republic of Moldova19, with a median of 110. Any resistance among previously treated cases No resistance was reported in Iceland, Israel or Norway, where the number of previously treated cases was very small. In contrast, high prevalence of any resistance was seen in Baku City, Azerbaijan (84. In 16 settings, prevalence of any resistance was reported as 50% or higher (Figure 4). Tashkent, Uzbekistan Baku City, Azerbaijan Jordan Lebanon Armenia Republic of Moldova Donetsk Oblast, Ukraine Inner Mongolia Auton. Tashkent, Uzbekistan Baku City, Azerbaijan Estonia Republic of Moldova Lithuania Donetsk Oblast, Ukraine Inner Mongolia Auton. Fifteen settings reported a prevalence of isoniazid resistance 30% or higher among previously treated cases (Figure 6). Figure 6: Prevalence of any resistance to isoniazid among previously treated cases, 2002–2007. Armenia Republic of Moldova Estonia Donetsk Oblast, Ukraine Lithuania Jordan Inner Mongolia Auton. Therefore, when estimating proportions of resistance among combined cases, proportions must be weighted by their population within the programme; this generates wide confidence levels. Rifampicin resistance unaccompanied by isoniazid resistance is rare, and may thus also be a good laboratory indicator. The median sample size was 335 for new cases, and ranged from 169 new cases in Cuba to 1809 in Peru. The median sample size was 264 for new cases, and ranged from 111 new cases in Jordan to 1049 in Morocco. A total of 30 countries conducted routine nationwide surveillance, with three settings in Spain. The median of combined cases tested was 483, and ranged from 8 in Iceland to 4800 in the United Kingdom. Data on previously treated cases were not included from the Mary El or Tomsk oblasts of the Russian Federation. Of the six countries, the median number of new cases tested was 547, and ranged from 101 in Mimika district in the Papua province of Indonesia to 1571 in Gujarat, India. India, Nepal and Myanmar showed similar proportions of resistance among re-treatment cases. Six countries reported data distinguished by treatment history, including four settings in mainland China. Among these settings, seven were able to report information for more than one year. The settings that reported were Cuba, Honduras, Latvia, Tomsk Oblast (Russian Federation), Barcelona and Galicia (Spain), Donetsk Oblast (Ukraine) and Uruguay. Data on new and previously treated cases were combined; data from multiple years were also combined if available. Data from the national laboratory registers in South Africa are included in the table, although these data are not considered nationally representative. Nineteen countries have reported at least one case since 2001, although no 24 Lyepshina S. Of the settings conducting routine surveillance, three countries and one oblast of the Russian Federation reported between 25 and 58 cases over a four-year period representing 6. Over a four-year period, Barcelona, Spain reported three cases and the Czech Republic reported five cases; these cases represented 8. During this time, Australia, France, Ireland, the Netherlands, Slovenia and Sweden reported one case; and Israel, Romania, and Canada reported two cases. Emergence of Mycobacterium tuberculosis with Extensive Resistance to Second-Line Drugs – Worldwide, 2000–2004. Management of multi drug resistance tuberculosis in the field: Tuberculosis Research Centre experience. To estimate the global and regional means of resistance, and to examine the distribution of resistance within a region, this report includes data obtained since the beginning of the project, weighted by the population they represent. The figures given in Table 7 correspond to the population-weighted means described in Table 8 and shown in Figures 14–17. Table 6 shows that the relationship between resistance to specific drugs across regions and by history of previous treatment was similar, with the highest proportions of resistance to isoniazid and streptomycin, followed by rifampicin and ethambutol. This was true for all regions, without regard to treatment history, with the exception of previously treated cases in the Eastern Mediterranean region, where rifampicin resistance was higher than isoniazid resistance. A box plot also indicates which observations, if any, might be considered outliers. Outliers may present valuable epidemiological clues or information about the validity of data. Box plots are able to visually show different types of populations, without making any assumptions of the underlying statistical distribution.

This is also the time for them to get dictations done and to complete face sheets generic luvox 50mg mastercard social anxiety. It is the goal during this time to get various specialties to come in and teach around patients that are on the ward buy discount luvox 50 mg line anxiety and nausea. The attendings will decide how to split the group up to get the maximum out of these sessions cheap 100mg luvox mastercard anxiety vs depression. Although the Senior Pediatric Resident is expected to lead these sessions, the Team 1 and 2 attendings are expected to be there and provide input. Case‐based teaching run by Team 1 and 2 on the 2nd and 3rd Wednesdays and the 4th Wednesday of the month will be Peds. This would be the opportunity for the attending paediatricians to do at least one long case examination with the pediatric residents, if possible. However, depending on how busy the teams are there is not a mandatory expectation. This would be the time to give residents mid‐way evaluations, as well as end of rotation evaluations. At least one of the three attendings will meet with learners to discuss objectives and expectations. Journals (all accessible via e-Resources at McMaster Libraries) • Pediatrics In Review. Developmental Milestones (if relevant): • Have you ever had any concerns about your child’s development? Postural vitals, Neuro vitals) Monitor: Accurate Ins & Outs (Surgery, volume status pts. Differential Diagnosis if anything has been ruled in/out Plan (A/P or I/P): Issue (1) Æ eg. Any subsequent additions or changes should be dated and signed at the time you make them, to avoid undermining the credibility of any changes. Poor charting may be perceived as reflecting less attention to detail, risking the conclusion that care provided was poor. Refer to separately dictated note for full history and physical examination of admission. Seek additionaladvise/appropriate consultationinth e eventoffluid and electrolyte abnorm alities. Ingeneralmaintenance fluid rate is calculatedby th e “4:2:1”guideline,butsh ould be 0-10 4/kg/h our individualiz edaccordingto th e clinicalconditionandpatientassessment Step2:Th e ch oice offluid is dependentth e individualpatient. U rine osmolarity/sodium andplasmaosmolarity as indicated,fordeterminingetiology ofh yponatraemia. Prior to the feed the nurse will generally draw back to see if there is any residual feed in the stomach. Reported as 0/37, scant/37 or 5/37 where the first number represents the volume of the residual and the second number the volume of the feed given. Histogram- continuous monitoring of oxygen saturations over 1-2 hrs, done in either prone or supine position. Reported as greater than 90 over 90, first number represents the saturation the second the percentage of the time that they over that saturation. Awaiting further investigations/consult Differential Diagnosis P: Outline plan by issue: include investigations, treatment, discharge plans. Birth Parameters Discharge Parameters Gestational age: Corrected and chronological age: Weight:____ g (%ile) Weight:____g Length: _____ cm (%tile) Head circumference:____cm (%ile) Head circumference:_____cm Maternal History and Delivery: ____________was born at McMaster University Medical Centre/elsewhere on (date) at ___ weeks gestational age to (parents’ full names). Patent Ductus Arteriosus/Cardiovascular Anomalies: The infant was treated/not treated with a course of Indomethacin on (date) for a patent ductus arteriosus that presented clinically/(or) was confirmed on echocardiogram. Sepsis: Cultures drawn following delivery were negative/(or) positive for (name of organism). Due to clinical deterioration(s) the infant had a partial/(or) full septic workup(s) on (date) which grew (name of organism) and was treated with (name of antibiotic). During the neonatal course the infant had__ episodes of sepsis which were culture negative/positive (state organism(s) if identified) Neurological: Cranial ultrasound(s) done on __day of life showed___(include date and result of most recent ultrasound). The most recent examination on (date) revealed zone__stage __ with no plus disease. A follow-up eye appointment has been made at the eye clinic at McMaster for (date and time). On (date) the serum sodium was __mmol/L, calcium was__mmol/L, and phosphate was __mmol/. Discharge Medications: Include iron, calcium/phosphate, vitamins Neonatal Screens: 1. Follow-up The infant requires follow-up for retinopathy of prematurity and cranial ultrasounds as well as (indicate any follow-up required including growth and development, appointments, etc. M inerals (M aintenance intakes forstable,growing infants) (2) Due to th e lim its ofsolubility ofcalcium and U sualDose Term Infants > 3kg ph osph orus inam ino acid solutions,th e (m m ol/kg/day) (m m ol/kg/day) m axim um dose of15 m m olofcalcium and S odium 2 -4 (1) 2 ph osph orus perlitre ofam ino acid solutioncan P otassium 1 -2 2 only be attained ifth e totalam ino acid M agnesium 0. Trace Elem ents S ource: m cg /m L Æ Z inc C opper S elenium C h rom ium M anganese Iodine N eo Trace Elem entM ix 425 19 2 0. Prevention of Perinatal Group B Streptococcal Disease: a public health perspective. American Academy of Pediatrics, Committee on Infectious Diseases and Committee on Fetus and Newborn. Prevention of early onset neonatal group B streptococcal disease with selective intrapartum chemoprophylaxis. When signs of sepsis are present, a lumbar puncture, if feasible, should be performed. If lab results and clinical course do not indicate bacterial infection, duration may be as short as 48 hours. Ongoing newborn assessment and timely interventions should not be limited by these guidelines. If at any point the newborn is symptomatic or otherwise unwell, notify the Family Physician or Midwife who may then choose to consult a Pediatrician.

Similarly 100 mg luvox otc anxiety symptoms test, a significantly higher proportion were referred to carotid surgery within 7 days or less or 30 days or less 50mg luvox anxiety symptoms upon waking up. However generic 100 mg luvox with amex social anxiety, there was a significantly longer delay in seeking medical attention from primary care to assessment in clinic in phase one (median 3 days) compared with phase two (median less than 1 day). A significantly higher proportion of patients were seen within 6 hours or less 31 Stroke from first call to medical attention to assessment in the study clinic in phase two than in phase one. Consequently, there were significantly fewer recurrent strokes after presentation to primary care but before assessment in clinic in phase two than in phase one. Median time from seeking medical attention to first prescription of one or the other treatments recommended in the faxed letter from the study clinic to primary care was significantly longer in phase one than in phase two (20 vs 1 day). Due to the different study populations and outcomes, the results of each study are presented separately. These patients were followed up prospectively for 1 month to derive a 30-day risk of stroke. This group included the four strokes that occurred within 7 days and six of the seven strokes that occurred at 90 days. This decreased the number of false positives from 44 to 21 at 7 days and from 42 to 19 at 90 days, without changing the scores’ ability to predict stroke. Overall, when the four validation groups were combined 47/4,799 (1%) patients with complete information in the combined cohorts scored 0, 191 (4%) scored 1, 543 (11%) scored 2, 847 (18%) scored 3, 11,165 (24%) scored 4, 994 (21%) scored 5, 852 (18%) scored 6, and 160 (3%) scored 7. Immediate specialist assessment dominated weekly specialist assessment, that is to say it was more effective and less expensive than weekly specialist assessment. Furthermore, the model does not capture the health gain attributable to increased uptake of statins and certain other drugs, which are costed in the model. If they had been included, then immediate specialist assessment would have appeared even more cost effective. This before and after cohort study found a relative reduction in stroke risk of about 80% for immediate specialist assessment compared to an appointment-based clinic. The level of risk that might be acceptable to patients of completed stroke whilst waiting 7 days for a clinic appointment was discussed with the patient representatives on the group. Informing patients of the risk they run whilst awaiting an appointment would cause unacceptable levels of anxiety and distress; they would want appropriate management without delay. The health economic modelling evidence (please refer to Appendix C for more information, available online at www. Secondary prevention includes antiplatelet agents, blood pressure management, anticoagulation in selected patients e. Specialist assessment includes: q exclusion of stroke mimics q identification of vascular territory 38 5 The rapid recognition of symptoms and diagnosis q identification of likely causes q appropriate investigation and treatment. Early carotid scanning is essential to exclude significant carotid stenosis in patients who would fulfil criteria for carotid endarterectomy (see section 6. The selection of patients for urgent scanning is dependent on clinical features; it is important that brain scanning does not delay the institution of optimum secondary prevention or the detection and treatment of significant carotid stenosis. Brain imaging is of potential value in the detection of stroke mimics and in establishing the diagnosis where this is in doubt. An expert consensus was agreed that patients with severe comorbidities may not be appropriate for scanning if the results would not change management. Brain imaging is of value in determining the presence of vascular lesions (which may be helpful if there is diagnostic doubt) and helping to establish vascular territory where this is not clear. The urgency of the carotid imaging depends on the individual’s risk of stroke (defined on clinical criteria: see section 6. Furthermore the value of carotid surgery decreases with time from the event, surgery ceases to be of value after 12 weeks of the event in trials for men and 2 weeks for women. Imaging should therefore be done rapidly if appropriate patients are to be assessed for surgery in a timely manner. No attempt was made to assess whether carotid imaging is cost effective compared with no carotid imaging in any population. The results were used to produce a simple strategy that could be used to identify who should be referred early for duplex imaging. When complete occlusion was included in the analysis, diabetes was no longer significantly associated with severe carotid stenosis. Scanning patients with three out of the four factors has the specificity of 97%, but sensitivity only 17%. Scanning any patient with one or more of these aforementioned features results in the highest sensitivity of 99%, but specificity dropped to 22%. This included most strategies with ultrasound as first or repeat test, and not those with intra- arterial angiography. However, the model was sensitive to less invasive test accuracy, cost and timing of endarterectomy. The cost effectiveness of carotid imaging compared with no carotid imaging could not be easily inferred from this study. The evidence does not identify any clinical sign that is pathognomonic for carotid stenosis although some (e. The group therefore agreed that all people who are suitable for carotid interventions should have access to carotid imaging. Similarly, a case-series study reported no perioperative complications associated with early carotid stenting (<14 days) in patients with symptomatic carotid artery stenosis. The clinical question is which patients with symptomatic carotid stenosis should be referred for early interventional procedures. It is of note that the lack of standardisation of the definition of significant carotid stenosis can be confusing. It is important that those reporting carotid imaging studies clearly state which criteria for diagnosis are being used. The data are reported according to time from last symptomatic ischaemic event to randomisation or surgery. The two trials used different techniques to measure the degree of carotid stenosis and each trial made different recommendations regarding the degree of stenosis above which surgery was effective. Twelve patients underwent the procedure within 24 hours of symptom onset for stroke in evolution. The degree of stenosis, or its statistical association with outcome, was not reported in this study. This shows that the effects of surgery are modified by time since last event, gender and age such that the benefit statistically decreases as the time since last symptoms increases, and is significantly greater in males than females and in the elderly.

Environmental Assessment It is important to conduct environmental assessment and collect environmental samples for suspected and potential causes of food borne illnesses especially of out breaks generic 100 mg luvox with visa anxiety kit. The assessment may include survey of the source of the out–break with critical evaluation of: 35 ¾ Source of the suspected food purchase luvox 50 mg without a prescription anxiety chest pain; ¾ How the food is prepared including cleanliness of table and kitchenware buy generic luvox 50 mg anxiety 6 weeks postpartum; ¾ Personal hygiene and health status of food handlers; ¾ Sanitation of the food preparation and service premises; ¾ Storage of the food before and after its preparation; ¾ Presence of potential or actual contaminants; ¾ Availability of safe and adequate water supply; ¾ Availability of safe and adequate sanitary facilities; ¾ Type and quality of food storage, and service equipments including food contact surfaces. Sites of infection and areas of spread may include the farm of origin, dealers, markets, processing areas, wholesale or retail outlets to catering establishments, restaurants and domestic kitchens. General Management Approaches of Food-borne Diseases The management approach to food-born diseases depends on the identification of specific causative agent, whether microbial, chemical or other. In addition determination of whether specific therapy is available and / or necessary or not is very important issue to consider. If an antimicrobial is required the choice should be based on: ¾ Clinical symptoms and signs ¾ Organism identified from specimens ¾ Antimicrobial susceptibility test, and ¾ Availability of drugs for the identified organisms. However, the limitation of facilities will have a negative impact on the choice of the specific management approach. Prevention and Control of Food-borne Diseases Prevention and control of food–borne diseases, regardless of the specific cause, are based on the same principles: 1. Specific modes of intervention vary from area to area depending on environmental, economic, political, technology and socio cultural factors. The preventive and control strategies may be approached based on the major site in the cycle of transmission or acquisition where they are implemented. Interventions at the source of infection include: ¾ Thorough cooking of raw food ¾ Thorough washing of raw vegetables with clean water ¾ Keeping uncooked animal products far separate from cooked and ready-to-eat foods. Use safe water Safe Food Handling: Require strict personal hygiene from all employees, and relieve infected employees of food handling duties. Investigation of Outbreaks of Food-borne Diseases Outbreaks of food-borne diseases can lead to deaths of many people within short periods, and hence their timely detection and proper management should not be undermined. When the Health Team receives information regarding an outbreak of a possible food-borne disease, action should start immediately. This action has to be integrated from the outset since the investigation and management of any outbreak requires the concerted effort of all health professionals concerned. In addition, being prepared beforehand for such outbreaks, by collecting the necessary information on food-borne diseases and previous outbreaks (in the area in particular) is important. The objectives of investigating an outbreak of a food-borne disease are to: ¾ Identify the causative agent responsible for the outbreak ¾ Identify the food items, handlers, etc. It will be helpful to have and keep a list of symptoms and signs during assessing these 40 individuals for the presence or absence of the suspected food-borne illness (nausea, vomiting, diarrhea, abdominal pain, fever, headaches, etc. During this visit, all members of the team should go and analyze the environment and other situations in a systematic way; they have to keep records of all things observed. Verify the existence of an outbreak 41 Compare the current number of cases with the past Note: Consider seasonal variations 2. Please go to the Satellite Module that applies to your specific professional category for continued thorough study. Ato Amsalu, a 28 year old patient, came from Asayta town to your health center complaining of fever and chills of a week’s duration accompanied with headache, dry cough, abdominal pain, and reduced frequency of stooling. On examination, you find the following: The patient is acutely sick looking 0 Axillary temperature is 38. Which of the following investigations is not as useful as the others in this patient to clarify his problem? Your health center has recently run out of reagents needed for carrying out blood film, Widal test as well as Weil-felix test. She came to your health center and told you that she has passed only 2 loose stools up to the time of presentation and that she has no fever but mild crampy abdominal pain. On examination, you find that her vital signs are all within normal limits and she has no signs of dehydration. Your request for stool examination returns with the following report: the gross appearance showed only loose stool with no mucus or blood and the microscopy revealed no fecal leukocytes or parasite. The most important measure in the management of this patient is: a) Oral fluid support b) Use of antidiarrheal agents such as Lomotil c) Prescription of ciprofloxacin for 5-7 days d) Investigation for possible typhoid fever e) A and D. Patients with reduced gastric acidity such as those with antacid ingestion have increased susceptibility to salmonella infection (9,23) Then they cross the intestinal barrier mainly through phagocytic cells overlying Peyer’s patches. At least two serum specimens, obtained at intervals of 7-10 days are needed to prove a rise in antibody titer. The interpretation is as follows: o High or rising titer of O (>1:160) suggests active infection o High titer of H (>1:160) suggest past infection. Results of serologic tests for salmonella infections must be interpreted cautiously; the possible presence of cross-reactive antibodies limits the use of serology in the diagnosis of salmonella infections. However, in areas where facilities for culturing are not available, the Widal test if performed reliably and interpreted with care, in addition to clinical features, can be of value in diagnosing typhoid fever. General Measures (9,24,25) include: Fluid and electrolyte support Antipyretic-analgesics as required such as paracetamol Close monitoring of the clinical course of the patient If there is suspicion of gastrointestinal hemorrhage or perforation, the patient should be immediately referred to a better health facility for appropriate management (blood transfusion, surgery). Chemotherapy: The symptoms are usually self-limited and antibiotic treatment is generally not recommended for Salmonella gastroenteritis. This usually develops towards the end of the first week (9) Seizures Reactive arthritis (Immunologically mediated joint inflammation seen in some patients following shigellosis; it may also follow some other bacterial infections, e. For intravenous fluid replacement, the best fluid to give is Ringer’s lactate as it also helps to correct acidosis, which is common in severely dehydrated patients. Antimicrobial therapy (see annex) This is not necessary for cure, but will diminish the duration and volume of fluid loss and will hasten clearance of the organism from the stool. This leads to nutrient malabsorption resulting in osmotic diarrhea (9, 23) Enteric caliciviruses like Norwalk virus result in disturbance of the architecture of the small intestine with shortening of villi and infiltration of lamina propria by polymorphs. One-third of children with rotavirus diarrhea may have fever of more than 0 39 C (9) Norwalk infection causes abrupt onset of nausea and abdominal cramps after an incubation period of 18-72 hours followed by vomiting and/or diarrhea. Clinical features-history of exposure should be sought; exclude drugs and alcohol as possible causes 2. Amebic Liver Abscess: The liver is the most common site of extra-intestinal Amebiasis Most patients have fever, right-upper quadrant pain (dull or pleuritic), point tenderness over the liver and right-sided pleural effusion (common), jaundice (rare) (9) Fewer than 30 % of patients have active diarrhea (9) Patients from endemic areas may present with prolonged fever, weight loss and hepatomegaly 10-15 % of patients present only with fever. Laboratory diagnosis: Depends on the identification of cysts in the feces or of trophozoites in the feces. Repeated examination of the stool may be necessary since cyst excretion is variable and may be undetectable at times.

B cells undergo a maturation process in the bone marrow discount luvox 50mg visa anxiety symptoms breathing problems, whereas T cells undergo maturation in the thymus generic luvox 50mg with mastercard anxiety 7 year old daughter. The functions of lymphocytes are complex and will be covered in detail in the chapter covering the lymphatic system and immunity cheap 50mg luvox fast delivery anxiety 37 weeks. Smaller lymphocytes are either B or T cells, although they cannot be differentiated in a normal blood smear. Abnormally high lymphocyte counts are characteristic of viral infections as well as some types of cancer. They are typically easily recognized by their large size of 12–20 µm and indented or horseshoe-shaped nuclei. Macrophages are monocytes that have left the circulation and phagocytize debris, foreign pathogens, worn-out erythrocytes, and many other dead, worn out, or damaged cells. Macrophages also release antimicrobial defensins and chemotactic chemicals that attract other leukocytes to the site of an infection. Abnormally high counts of monocytes are associated with viral or fungal infections, tuberculosis, and some forms of leukemia and other chronic diseases. Lifecycle of Leukocytes Most leukocytes have a relatively short lifespan, typically measured in hours or days. Secondary production and maturation of lymphocytes occurs in specific regions of lymphatic tissue known as germinal centers. This capacity enables an individual to maintain immunity throughout life to many threats that have been encountered in the past. Although leukocyte counts are high, the cells themselves are often nonfunctional, leaving the individual at increased risk for disease. It may involve only one specific type of leukocyte from either the myeloid line (myelocytic leukemia) or the lymphoid line (lymphocytic leukemia). Lymphoma is a form of cancer in which masses of malignant T and/or B lymphocytes collect in lymph nodes, the spleen, This OpenStax book is available for free at http://cnx. As in leukemia, the malignant leukocytes do not function properly, and the patient is vulnerable to infection. Others tend to progress quickly and require aggressive treatment, without which they are rapidly fatal. Platelets You may occasionally see platelets referred to as thrombocytes, but because this name suggests they are a type of cell, it is not accurate. A platelet is not a cell but rather a fragment of the cytoplasm of a cell called a megakaryocyte that is surrounded by a plasma membrane. As noted earlier, thrombopoietin, a glycoprotein secreted by the kidneys and liver, stimulates the proliferation of megakaryoblasts, which mature into megakaryocytes. Following platelet release, megakaryocyte remnants, which are little more than a cell nucleus, are consumed by macrophages. Platelets are relatively small, 2–4 µm in diameter, but numerous, with typically 150,000–160,000 per µL of blood. After entering the circulation, approximately one-third migrate to the spleen for storage for later release in response to any rupture in a blood vessel. They also secrete a variety of growth factors essential for growth and repair of tissue, particularly connective tissue. If there is an insufficient number of platelets, called thrombocytopenia, blood may not clot properly, and excessive bleeding may result. There is a chance to review each of the leukocytes individually after you have attempted to identify them from the first two blood smears. Try constructing a simple table with each leukocyte type and then making a mark for each cell type you identify. Based on the percentage of cells that you count, do the numbers represent a normal blood smear or does something appear to be abnormal? Although rupture of larger vessels usually requires medical intervention, hemostasis is quite effective in dealing with small, simple wounds. There are three steps to the process: vascular spasm, the formation of a platelet plug, and coagulation (blood clotting). Vascular Spasm When a vessel is severed or punctured, or when the wall of a vessel is damaged, vascular spasm occurs. The circular layers tend to constrict the flow of blood, whereas the longitudinal layers, when present, draw the vessel back into the surrounding tissue, often making it more difficult for a surgeon to locate, clamp, This OpenStax book is available for free at http://cnx. The vascular spasm response is believed to be triggered by several chemicals called endothelins that are released by vessel-lining cells and by pain receptors in response to vessel injury. Formation of the Platelet Plug In the second step, platelets, which normally float free in the plasma, encounter the area of vessel rupture with the exposed underlying connective tissue and collagenous fibers. The platelets begin to clump together, become spiked and sticky, and bind to the exposed collagen and endothelial lining. This process is assisted by a glycoprotein in the blood plasma called von Willebrand factor, which helps stabilize the growing platelet plug. As platelets collect, they simultaneously release chemicals from their granules into the plasma that further contribute to hemostasis. Plug formation, in essence, buys the body time while more sophisticated and durable repairs are being made. In a similar manner, even modern naval warships still carry an assortment of wooden plugs to temporarily repair small breaches in their hulls until permanent repairs can be made. Coagulation Those more sophisticated and more durable repairs are collectively called coagulation, the formation of a blood clot. The process is sometimes characterized as a cascade, because one event prompts the next as in a multi-level waterfall. The result is the production of a gelatinous but robust clot made up of a mesh of fibrin—an insoluble filamentous protein derived from fibrinogen, the plasma protein introduced earlier—in which platelets and blood cells are trapped. The process is complex, but is initiated along two basic pathways: • The extrinsic pathway, which normally is triggered by trauma. All three pathways are 2+ dependent upon the 12 known clotting factors, including Ca and vitamin K (Table 18. Vitamin K (along with biotin and folate) is somewhat unusual among vitamins in that it is not only consumed in the diet but is also synthesized by bacteria residing in the large intestine. Some recent evidence indicates that activation of various clotting factors occurs on specific receptor sites on the surfaces of platelets.