The release of prostaglandins in human aqueous humour following intraocular surgery. Effect of indomethacin

Inflammatory reaction to ocular trauma is known to be related to prostaglandins. To further evaluate this phenomenon in human, PGE₁ and E₂ were measured by R.I.A. after silicic acid chromatography in aqueous humour of 26 patients before and 3 days after surgery for unilateral senile cataract (posterior chamber implant after extracapsular surgery). 13 out of these patients were treated with indomethacin by enteral route and 13 were not treated.PGE₂ levels increased in all non-treated patients from : m < 214 pg/ml before surgery, to 2666 ± 869 pg/ml (range : 257 - 8728) p < 0.001 after surgery. PGE₂ levels did not increase in indomethacin-treated patients. PGE₁ levels did not increase significantly in non-treated as in treated patients.1) Intra-ocular surgery is followed in human by a constant increase of the only PGE₂ in the aqueous humour. 2) Indomethacin inhibits this increase. 3) The post-surgical increase in the permeability of blood-aqueous barrier appears to be related to a release of PGE₂.     

Clinical Problems: Progressive Neurological Deficits in Primary Polycythaemia

Patients with primary polycythaemia may present clinical features which lead to an erroneous diagnosis of intracerebral neoplasm. Three such cases are described in detail in this report.     

Glycerol and dihydroxyacetone dissimilation in Desulfovibrio strains

During growth on glycerol two marine Desulfovibrio strains that can grow on an unusually broad range of substrates contained high activities of glycerol kinase, NAD(P)-independent glycerol 3-phosphate dehydrogenase and the other enzymes necessary for the conversion of dihydroxyacetone phosphate to pyruvate. Glycerol dehydrogenase and a specific dihydroxyacetone kinase were absent. During growth on dihydroxyacetone, glycerol kinase is involved in the initial conversion of this compound to dihydroxyacetone phosphate which is then further metabolized. Some kinetic properties of the partially purified glycerol kinase were determined. The role of NAD as electron carrier in the energy metabolism during growth of these strains on glycerol and dihydroxyacetone is discussed.Glycerol also supported growth of three out of four classical Desulfovibrio strains tested. D. vulgaris strain Hildenborough grew slowly on glycerol and contained glycerol kinase, glycerol 3-phosphate dehydrogenase and enzymes for the dissimilation of dihydroxyacetone phosphate. In D. gigas which did not grow on glycerol the enzymes glycerol kinase and glycerol 3-phosphate dehydrogenase were absent in lactate-grown cells.Abbreviations DHA dihydroxyacetone - DHAP dihydroxyacetone phosphate - G3P glycerol 3-phosphate - GAP glyceraldehyde 3-phosphate - 3-PGA 3-phosphoglycerate - 2-PGA 2-phosphoglycerate - 2,3-DPGA 2,3-diphosphoglycerate - PEP phosphoenolpyruvate - DH dehydrogenase - GK glycerol kinase - DHAK dihydroxyacetone kinase - TIM triosephosphate isomerase - PGK 3-phosphoglycerate kinase - PK pyruvate kinase - LDH lactate dehydrogenase - DTT dithiotreitol - HEPES 4-(2-hydroxyethyl)-1-piperazine ethane sulfonic acid - PIPES piperazine-1,1-bis(2-ethane sulfonic acid) - BV²⁺/BV⁺ oxidized/reduced benzylviologen - PMS phenazine methosulfate - DCPIP 2,6-dichlorophenolindophenol - MTT 3-(4,5-dimethylthiazol-2-yl)-2,4-diphenyltetrazolium bromide     

Growth dynamics of a ctenophore (Mnemiopsis) in relation to variable food supply. II. Carbon budgets and growth model

Our goal was to test our understanding of ingestion, assimilationefficiency and metabolism for Mnemiopsis mccradyi by formulatingand validating a simulation model of growth under differentconditions of food availability. The model was based on a carbonbudget approach using formulations derived from empirical results,including how each process was affected by food availabilityand ctenophore size. An experimentally measured carbon budgetfor pulsed food availability indicated that, relative to totalingestion, growth was high (17–48%), respiration plusorganic release was relatively low (24–48%) and little(<10%) of the ingested carbon was unaccounted for. New laboratoryinvestigations of feeding and assimilation efficiency were necessaryto refine the formulations so that model predictions comparedfavorably with a variety of laboratory measurements of growth,and growth efficiency, as well as the complete experimentallymeasured carbon budget. The refined model predicted a high ratioof growth to metabolism (>2) and a high gross growth efficiency(>30%) for smaller ctenophores at high food concentrations(>20 prey l^–1). Both growth rates and growth efficiencieswere predicted to decrease for larger ctenophores. Model predictionswere generally consistent with experimental results, includinginvestigations using pulsed food availability to simulate environmentalpatchiness. Although the model underpredicted ctenophore growthin some experiments at low food densities, the model predictionof a minimum prey concentration of about 8 l^–1 (24 µgC l^–1) for sustaining a ctenophore population of reproductivesize agreed with field observations.     

Growth dynamics of a ctenophore (Mnemiopsis) in relation to variable food supply. I. Carbon biomass, feeding, egg production, growth and assimilation efficiency

This paper contains new experimental data on the growth dynamicsof a lobate coastal ctenophore, Mnenmiopsis mccradyi, whichadd significantly to our understanding of the nutritional ecologyof ctenophores and their role as opportunistic predators. Theseexperimental observations were necessary to refine the dynamiccarbon budget presented as a simulation model in another report.The ratio of carbon biomass to dry weight may vary several-folddepending on the nutritional state and size from >12% inwell-fed larvae to <1% in starved adults. Feeding effort(clearance rate) is higher for previously starved animals, fallingsharply within a few hours after re-exposure to food. Directvisual observations of feeding activity of animals confirmedthis. Assimilation efficiency can be high (72%) in these animalsbut if they continue to feed at high food concentrations, incomingfood displaces material which is only partially digested andassimilation efficiency decreases substantially. Except at verylow food concentrations, growth efficiency ranges between 20and 45%. Mnemiopsis, begins to produce eggs at a size much lessthan its maximum. Egg production is very sensitive to food supply,and somatic growth is favored over egg production at low fooddensities. Even though several thousand eggs may be producedover a few days, they represent <2% day^–1 of the carbonbiomass of the ctenophore and several-fold less than respiratorycarbon.     

Identification of centromere proteins in different mammalian cells

The characterization of centromeric proteins is facilitated using anti-centromere antibodies present in the sera of patients with the CREST variant of scleroderma. We have employed these sera to determine whether or not those proteins are present in different mammalian species, as well as to study their tissue distribution. Here, we describe the immunofluorescent pattern and the proteins recognized by CREST sera in dividing and resting cells from mouse, rat, swine, hamster, rabbit, and man. In nuclear preparations from cultured cells, thymocytes and spermatozoa from these species, the antigens recognized by CREST sera are proteins of 18 to 20 kDa in all species tested, except in rat. Additionally, two peptides of 80 and 140 kDa were observed in human preparations. In contrast, a 50 kDa peptide is the primary protein detected by the sera in rat nuclei.     

Primary (essential) thrombocythemia versus polycythemia vera rubra. A histomorphometric analysis of bone marrow features in trephine biopsies

A morphometric analysis of bone marrow biopsies was performed in 25 patients each with clinical diagnoses of primary (essential) thrombocythemia (PTH) and polycythemia vera rubra (P. vera) according to the rigid diagnostic criteria of the Polycythemia Vera Study Group to reveal significant differences in the histomorphologic features between these disorders. In comparison with control specimens of patients without any hematologic disease, megakaryocyte proliferation was most prominent in PTH, even exceeding that of P. vera with concomitant thrombocythemia (11 of 25 cases with a platelet count greater than 600 X 10(9)/L). Moreover, in P. vera there were wide ranges of megakaryocyte sizes, consisting of micro-megakaryocytes as well as giant forms with highly segmented nuclei (four nuclear lobes), which gave the cells a pleomorphic appearance. As compared with the normal bone marrow, the amount of neutrophilic granulopoiesis and erythropoiesis was not significantly increased in PTH, in contrast to P. vera. Similar results were obtainable regarding the density of reticulin (argyrophilic) fibers: a normal content was encountered in the control specimens and PTH, whereas P. vera displayed a minimal-to-slight increase. Finally, the bone marrow of P. vera was totally devoid of stainable iron while hemosiderin deposits were detected in about two-thirds of the patients without hematologic disorders and in PTH. The characteristic differences revealed by this morphometric study may lead to an improvement of the controversial histologic diagnosis in these disorders.     

Interaction of atrial natriuretic peptide-stimulated guanylate cyclase and vasopressin-stimulated calcium signaling pathways in the glomerular mesangial cell

Receptors for atrial natriuretic peptide (ANP) have been demonstrated in renal mesangial cells as well as other cell types in the glomerulus. The biochemical basis for the effects of ANP on glomerular hemodynamics remains undefined. Using cultured rat glomerular mesangial cells, we demonstrated a concentration-dependent stimulation of cGMP production in intact cells, and of guanylate cyclase in membranes. Despite the presence of a guanylate cyclase response, ANP had no inhibitory effect on basal inositol trisphosphate production nor on basal cytosolic calcium. Arginine vasopressin stimulated IP3 production, caused a rise in cytosolic calcium as measured using the calcium-sensitive fluorescent probe Indo-1, and caused mesangial cell contraction. ANP caused a slight but significant enhancement of vasopressin-stimulated IP3 production, but had no effect on the cytosolic calcium response nor on the contractile response. 8-Bromo-cGMP likewise had no effect on the generation of the calcium signal. These results indicate that the effects of ANP on glomerular hemodynamics are not mediated by an alteration in the generation of the calcium signal in mesangial cells. In contrast, addition of calcium inhibited ANP stimulated guanylate cyclase activity.