Icosanoid production during platelet-neutrophil interactions.
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Biomedical subjects
Publications and source records attributed to N Islam.
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A total of 323 cases of cirrhosis of liver with various complications in some hospitalised population were studied. Microcytic anaemia was found to be the commonest (46.43 percent) complication. Next common (21.05) complication was protosystemic encephalopathy (PSE). Gastrointestinal haemorrhage and primary carcinoma of liver constituted 12.37 percent and 9.28 percent respectively. In view of the nature of complications of liver, it was felt necessary that these type of patients should be exposed to facilities for the specialised management whenever possible. Development of primary carcinoma of liver emphasises the need for the prevention of hepatitis B virus infection for which preventive vaccine is now available.
We studied interactions of human platelets and neutrophils with particular reference to the arachidonic acid pathway. Suspensions of [3H]arachidonate-labeled platelets and unlabeled neutrophils were stimulated with ionophore A23187. We detected several radioactive arachidonate metabolites, which are not produced by platelets alone. These included [3H]-labeled leukotriene B4 (LTB4), dihydroxy-eicosatetraeonic acid (DiHETE), and 5-hydroxy-eicosatetraenoic acid (5-HETE). DiHETE was formed when the platelet product [3H]12-HETE was added to ionophore-stimulated neutrophils. In addition, DiHETE was the major metabolite when [3H]5-HETE, a neutrophil arachidonate product, was added to stimulated platelets. We therefore suggest that upon stimulation, platelet-derived arachidonate can serve as precursor for the neutrophil-derived eicosanoids LTB4 and 5-HETE, and the platelet-derived product 12-HETE can be metabolized to DiHETE by stimulated human neutrophils. More recently we have shown that 12-HETE from thrombin-stimulated platelets can also be metabolized to a new product, 12,20-DiHETE, by unstimulated human neutrophils. It would appear that the platelet and neutrophil lipoxygenase pathways take part in cell-cell interactions--an observation that suggests a role for the neutrophils that are present in hemostatic plugs, thrombi, and inflammatory processes.
A new metabolite of arachidonic acid, formed during interaction between thrombin- or collagen-stimulated platelets and unstimulated neutrophils, has been demonstrated by both thin-layer radiochromatography and high-performance liquid chromatography. Production of the 3H-labeled metabolite in combined suspensions containing [3H]arachidonate-labeled platelets and unlabeled neutrophils from aspirin-treated donors suggested that platelet 3H-labeled 12S-hydroxy-5,8-cis,10-trans,14-cis-icosatetraenoic acid (12-HETE) was the precursor. This was confirmed by identification of the same product when purified 12-[3H]HETE was added directly to unstimulated neutrophils. Hydrogenation and oxidation of the isolated product, followed by gas chromatography-mass spectrometry showed the structure to be 12S,20-dihydroxyicosatetraenoic acid. These experiments further show that platelet stimuli known to occur in vivo may initiate metabolic interactions between different cell types via the arachidonic acid pathway.
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We studied interactions of human platelets and neutrophils with particular reference to the arachidonic acid pathway. Suspensions of [3H]-arachidonate-labeled platelets and unlabeled neutrophils were stimulated with ionophore A23187. We detected several radioactive arachidonate metabolites, which are not produced by platelets alone. This included [3H]-labeled leukotriene B4 (LTB4), dihydroxyeicosatetraenoic acid (DHETE) and 5-hydroxyeicosatetraenoic acid (5-HETE). When the platelet product, [3H]12-HETE, was added to ionophore-stimulated neutrophils, DHETE was formed. In addition, when [3H]5-HETE, a neutrophil arachidonate product, was added to stimulated platelets, DHETE was the major metabolite. We, therefore, suggest that upon stimulation, the platelet derived arachidonate can serve as precursor for the neutrophil-derived eicosanoids LTB4 and 5-HETE and that the platelet-derived product 12-HETE can be metabolized to DHETE by stimulated human neutrophils. It would appear that the platelet and neutrophil lipoxygenase pathways take part in cell-cell interactions - an observation which suggests a role for the neutrophils which are present in hemostatic plugs, thrombi and inflammatory processes.
Three thousand six hundred and ten patients with acute hepatitis in two large hospitals in Dhaka city were tested for HBsAg. Besides, 780 commercial blood donors, 126 doctors and 576 apparently healthy persons were also tested. Passive haemagglutination technique was applied for this test. Patients with post-transfusion hepatitis and doctors with acute hepatitis showed the highest incidence, being 60% and 65.5% respectively. HBsAg was detected only in 15.4% of children and 27.2% of adult patients with acute hepatitis.
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Out of 218 suspected cases of kala-azar from different parts of Bangladesh, 59 could be confirmed; and out of 41 patients with suspected skin lesions, 6 were confirmed as post-kala-azar dermal leishmaniasis. Confirmation of diagnosis was based on the demonstration of L-D bodies in tissue specimens (spleen and liver (after puncture) or skin scrapings).The complement fixation test (CFT) and aldehyde test (AT) were positive in all but one case of kala-azar. Their usefulness in the diagnosis of the disease has been emphasized. The aldehyde test is very simple to perform and does not require any equipment or electricity; it can therefore be used as a screening test in rural areas.Failure of the organism to grow in NNN medium in 2 cases and failure to maintain organisms isolated from some other cases for more than 2-3 weeks in the culture medium indicate the possibility that different strains were involved. As the number of kala-azar cases appears to be increasing, the threat of an epidemic is real.
A total of 5,026 persons constituting 75% of the total population of a village of Bangladesh were screened for elevated blood pressure. Three hundred thirty seven (6.7%) showed diastolic blood pressure of 90 mm Hg or above. Those with diastolic blood pressure of 95 or above constituted 2% of the population. 74% of the hypertensives were asymptomatic while 86.3% of the cases were undetected and therefore remained untreated. Our findings indicate the need for early detection and control of elevated blood pressure to prevent complications. It is recommended that a large scale community survey programme may be undertaken for detection and early treatment of hypertension which helps prevention of total complications.
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A total of 101 cases of rheumatic diseases collected during a period of six months from a hospital population have been analysed. These did not include rheumatic fever. Paediatric age group up to age of 12 years was not included in the series. Rheumatoid arthritis has been found to be the commonest condition, constituting 60 cases. Cervical spondylosis was next in common (24 cases). Ankylosing spondylitis and osteoarthritis constituted nine and six cases respectively. Emphasis has been laid on the bizarre manifestation of cervical spondylosis. The study, in spite of limitations throws some light on the relative frequency of rheumatic diseases other than rheumatic fever in Bangladesh.
Clinical analysis of 293 cases of cirrhosis from two moderate sized hospitals in the city of Dacca has been presented. Maximum number of cases were in the age group over 40 with 150 (51.2%) males and 19 (5.8%) females. Significant past history included viral hepatitis (21.5%), kala-azar (11.6%) and malaria (10.24%). History of alcoholism was present only in 16 (5.5%) cases. Weakness (84.3%), weight loss (72%) and anorexia (39.3%) constituted the most common symptoms. Ascites (45%), haematemesis (11.6%) and melaena (28.7%) were the next common symptoms. Hepatosplenomegaly was found in about one-third of the cases. Testicular atrophy was recorded in 41.63% cases whereas gynaecomastia was relatively less common (5.5%). Scanty body hair and white nails were present in almost equal number of cases (14.7% and 18%). The cases presented here are those with overt manifestation. Nevertheless, the clinical features are not materially different from those reported by other authors. In the absence of alcoholism, viral hepatitis is presumably the most important aetiological factor in our cases and the clinical features compare favourably with non-alcoholic cirrhosis of the western writers. Cryptogenic cirrhosis has been considered to be most common type constituting 43.7% of our cases.
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A total of 8,172 persons constituting 98.6% of the total Secretariate Population of Bangladesh were screened for elevated blood pressure. One thousand and ninety cases (13.3%) showed diastolic blood pressure of 90 mmHg or above. Those with diastolic blood pressure of 95 or above constituted 3.7% of the population. More than two-thirds of the latter group (71.6%) remained undetected indicating that vast majority of our hypertensive population remains undiagnosed and untreated. It is recommended that the misconception regarding symptomatic hypertenson should be removed by adequate emphasis on the preventive value of the control of hypertension on cardiovascular and cerebrovascular complication. A plea has also been made for a large-scale survey to determine the extent of the problem in Bangladesh.