Megakaryocytic cells synthesize and platelets secrete alpha5-laminins, and the endothelial laminin isoform laminin 10 (alpha5beta1gamma1) strongly promotes adhesion but not activation of platelets

Following vascular injury, basement membrane (BM) components of the blood vessels are exposed to circulating cells and may contribute to hemostasis and/or thrombosis. Laminins 8 (LN-8) (alpha4beta1gamma1) and 10 (LN-10) (alpha5beta1gamma1) are major laminin isoforms of the endothelial BM, and LN-8 is also secreted by activated platelets. In the present study, we demonstrate synthesis of alpha5-laminins LN-10 and LN-11 (alpha5beta2gamma1) by megakaryocytic cells, and intracellular expression of these laminin isoforms in blood platelets. In contrast to platelet LN alpha4 chain that had an apparent molecular weight of 180 kDa and associated mostly to LNbeta1 chain, platelet LNalpha5 consisted of 300/350 kDa polypeptides and associated mainly to LNbeta2. Both alpha4- and alpha5-laminins were secreted by platelets following stimulation. When compared to recombinant human (rh) LN-8, rhLN-10 was much more adhesive to platelets, though adhesion to both proteins was largely mediated via alpha6beta1 integrin. In spite of their adhesive properties, rhLN-8 and rhLN-10 induced neither P-selectin expression nor cell aggregation, two signs of platelet activation. This study demonstrates synthesis/expression of heterotrimeric alpha5-laminins in hematopoietic/blood cells, and provides evidence for the adhesive, but not activating, role of endothelial laminin isoforms in platelet biology.     

Early-onset neonatal seizures: types, risk factors and short-term outcome

In a large majority of term newborns, early-onset neonatal seizures (EONS) are believed to relate to perinatal risk factors. AIM: To identify risk factors for EONS. METHODS: Among a cohort of 1293 newborns admitted over a period of 2 years to the neonatal intensive care unit of Tikur Anbasa Hospital, Addis Ababa, 93 had seizures. The case control study method was used to identify risk factors associated with EONS. Univariate analysis was used to further examine risk factors after adjusting for the effect of severe perinatal asphyxia (Apgar < or = 3). RESULTS: A total of 78 (85%) term newborns had EONS. Hypoxic-ischaemic encephalopathy (OR 3.46, 95% CI 2.74-7.42) and shock (OR 2.53, 95% CI 1.51-4.76) were significantly associated with EONS. Multifocal clonic (66%) followed by focal clonic (22%) were the most common types of EONS. Nine (11%) of the newborns with EONS died. During follow-up, 37 (53%) of the 69 surviving newborns with EONS had psychomotor delay with or without neurological deficit. CONCLUSION: Hypoxic-ischaemic encephalopathy and shock are important causes of EONS.     

A multidisciplinary study of onchocerciasis in Bure area, Ethiopia

A clinicoepidemiological and entomological study of onchocerciasis was conducted in Bure area, Illubabor Administrative Region, in October 1987. All 1063 houses in four villages were numbered and census taken. The total population was 4119. Of the total 1063 houses, 107 (10.07%) were selected by systematic random sampling and all members of these households were examined. History, physical examination, and skin biopsy were taken. Of 4119 people in the area, 3555 (86.3%) were indigenous and 564 (13.7%) settlers. Four hundred and three of the former and 68 of the latter were studied. Clinical manifestations were mild and ocular onchocerciasis was not encountered. One hundred and sixteen (24.6%) had O. volvulus in the skin; with a mean of 11.7 microfilariae per milligram of skin. Positivity in males was 1 1/2 times that in females. None of the settlers had positive skin snips. We concluded that onchocerciasis is hypoendemic in Bure area with mild clinical manifestations. Adult and aquatic stages of Simulium were collected for later identification, and a preliminary report indicates that S. damnosum s.l. is the most likely vector.