An endogenous ligand for the central sulfonylurea receptor

An endogenous ligand for the rat central sulfonylurea receptor has been evidenced in the rat central nervous system. The characteristics of this ligand (extractibility, non-dialysability, chromatographic behaviour on different media, sensitivity to proteases) indicate that it is a neutral to slightly basic peptide.     

Biological control of tissue plasminogen activator-mediated fibrinolysis

Fibrinolysis, the body's ability to degrade fibrin, is an integrated part of hemostasis. Overactivity in the fibrinolytic system causes bleeding and underactivity causes thrombosis. Tissue plasminogen activator (tPA), plasminogen activator inhibitor type 1 (PAI-1), alpha 2-antiplasmin (alpha 2-AP) and plasminogen are definitely involved in fibrinolysis because: (1) these components can be assigned a fibrinolytic role in purified systems, i.e. in vitro, and (2) abnormal structural variants and abnormal levels of these components give rise to bleeding or to thrombosis. The biological control of tPA-mediated fibrinolysis is both cellular and humoral. The cellular regulation compasses synthesis of tPA and PAI-1 and release/uptake of these components. The humoral regulation involves: (1) the reaction between tPA and PAI-1; (2) the fibrin-stimulated plasminogen activation; (3) the reaction between plasmin and alpha 2-AP and (4) plasmin degradation of fibrin. The highly developed biological control of tPA-mediated fibrinolysis is indicative of its physiological importance.     

A polarized epithelial cell mutant deficient in translocation of UDP-galactose into the Golgi complex

Two lectin-resistant mutants derived from a polarized epithelial cell line have been described (Meiss, H.K., Green, R.F., and Rodriguez-Boulan, E.J. (1982) Mol. Cell. Biol. 2, 1287-1294). One of these mutants, the Madin-Darby canine kidney strain II cell line resistant to Ricinus communis agglutinin (MDCKII-RCAr), has been further characterized, and the biochemical defect leading to its altered phenotype has been determined. MDCKII-RCAr cells are shown to be enriched in cell-surface glycoconjugates bearing terminal N-acetylglucosamine residues by in vitro exogalactosylation and by labeling with fluorescent lectins. Binding assays with a sialic acid-specific lectin reveal a 70-75% reduction in sialylation of cell-surface glycoconjugates. The defect is pleiotropic in nature, affecting glycoproteins as well as glycosphingolipids. Analysis of glycosphingolipids shows a strong reduction of galactose-containing glycosphingolipids. Almost 90% of the glycosphingolipids are identified as glucosyl-ceramide. The mutant is not deficient in galactosyl- and sialytransferase activities. However, Golgi vesicles isolated from MDCKII-RCAr cells translocate UDP-galactose at only 2% of the rate observed for vesicles from wild-type MDCKII cells. The deficiency is specific, because translocation rates of UDP-N-acetylglucosamine and CMP-sialic acid are comparable for vesicles isolated from MDCKII-RCAr cells and wild-type cells. Despite the inability to translocate UDP-galactose into the lumen of the Golgi apparatus, MDCKII-RCAr cells are able to form monolayers with normal apical and basolateral polarity as shown by plasma membrane domain-restricted exogalactosylation.     

Serum steroid levels in intact and endocrine ablated BALB/c nude mice and their intact littermates

An investigation was made of the serum steroid levels found in intact and endocrine ablated nude mice of both sexes and in their intact homozygous littermates. The results showed that nude mice have a normal steroidogenesis, but with decreased levels of circulating steroids compared to those of the littermates. The efficacy of the endocrine ablations was confirmed by the reduction in serum oestrone following oophorectomy, and by the reduction in serum testosterone and progesterone following orchiectomy. The normal steroidogenesis in nude mice, and the similarities between mouse and man with regard to changes in serum steroids following oophorectomy and orchiectomy, support the usefulness of human tumor xenograft models for the study of hormone-tumor interactions.     

Physiological profile of world-class high-altitude climbers

The functional characteristics of six world-class high-altitude mountaineers were assessed 2-12 mo after the last high-altitude climb. Each climber on one or several occasions had reached altitudes of 8,500 m or above without supplementary O2. Static and dynamic lung volumes and right and left echocardiographic measurements were found to be within normal limits of sedentary controls (SC). Muscle fiber distribution was 70% type I, 22% type IIa, and 7% type IIb. Mean muscle fiber cross-sectional area was significantly smaller than that of SC (-15%) and of long-distance runners (LDR, -51%). The number of capillaries per unit cross-sectional area was significantly greater than that of SC (+ 40%). Total mitochondrial volume was not significantly different from that of SC, but its subsarcolemmal component was equal to that of LDR. Average maximal O2 consumption was 60 +/- 6 ml X kg-1 X min-1, which is between the values of SC and LDR. Average maximal anaerobic power was 28 +/- 2.5 W X kg-1, which is equal to that of SC and 40% lower that that of competitive high jumpers. All subjects were characterized by resting hyperventilation both in normoxia and in moderate (inspired O2 partial pressure = 77 Torr) hypoxia resulting in higher oxyhemoglobin saturation levels in hypoxia. The ventilatory response to four tidal volumes of pure O2 was similar to that of SC. It is concluded that elite high-altitude climbers do not have physiological adaptations to high altitude that justify their unique performance.     

The value of provoked expectoration in obtaining sputum samples for cytologic investigation. A prospective, consecutive and controlled investigation of 134 patients

A prospective controlled investigation in 134 consecutive outpatients compared the cytologic adequacy of sputum samples obtained by spontaneous and provoked expectoration. Inhalation of nebulized 10% sodium chloride was used for provoked expectoration. A significantly higher number of adequate samples was produced after provocation, as judged by the presence of alveolar macrophages (X2 = 5.63; p less than 0.02). The improvement in sample adequacy was limited to the nonsmokers and ex-smokers in the study. This result, together with the relatively high cost of cytologic sputum examinations, indicates that provoked expectoration should at least be applied to the collection of sputum samples from nonsmokers and ex-smokers.     

Ultrastruktur und Bildungsweise penialer Hartstrukturen bei freilebenden Plathelminthen

Zusammenfassung Ultrastruktur und Differenzierung von Penisstiletten bzw. Stilettnadeln wurden an Vertretern verschiedener Taxa freilebender Plathelminthen untersucht. Die Ausdifferenzierung der Hartstrukturen erfolgt auf unterschiedliche Weise, jedoch stets intrazellulär. Die Stilettnadeln von Philocelis cellata (Acoela) bestehen aus Mikrofibrillen und werden sukzessiv gebildet, mit der Spitze beginnend und basalwärts fortschreitend. Eine ebenfalls sukzessive Bildungsweise zeigen die Stilettapparaturen des Taxons Paromalostomum (Macrostomida); doch bestehen die Hartstrukturen hier aus Mikrotubuli mit angelagertem elektronendichtem Material und nicht aus Mikrofibrillen. Die sukzessive Ausdifferenzierung des Stiletts von Ciliopharyngiella intermedia erfolgt ähnlich wie bei den Hartstrukturen bestimmter Proseriaten mit der Anlage von Mikrofibrillen, die mit elektronendichtem Material verkleidet werden, jedoch weist C. intermedia zusätzlich eine innere und äußere Glättungsschicht auf. Dagegen erfolgt die Stilettbildung bei Adenorhynchus balticus (Typhloplanoida), Marirhynchus longasaeta (Kalyptorhynchia) und Provortex psammophilus und P. tubiferus (Dalyellioida) simultan und ohne Anlage einer Rohform mit einem fibrillären oder tubulären Gerüst. Strukturell sehr ähnlich wie bei A. balticus und M. longasaeta, jedoch sukzessiv erfolgt die Bildung der langen Stilette bei verschiedenen Species des Taxons Promesostoma (Typhloplanoida).Die bisher bekannten feinstrukturellen Organisationsmerkmale und die verschiedenen Bildungsmodi von penialen Hartstrukturen werden unter phylogenetischen Gesichtspunkten diskutiert.

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Ultrastructure and differentiation of penial hard structures in free-living plathelminths

Summary Ultrastructure and differentiation of penis stylets and stylet needles have been investigated in several representatives of different groups of the free-living plathelminths. The formation of the hard structures occurs in different ways, but always intracellularly. The stylet needles of Philocelis cellata (Acoela) consist of microfibrils and are formed successively, beginning with the distal tip. The species of the taxon Paromalostomum (Macrostomida) have stylet apparatuses which also show a successive formation mode; however, the hard elements are built of microtubules and enveloped by electron-dense material. The successive differentiation of the stylet of Ciliopharyngiella intermedia occurs similarly to the hard structure formation of certain proseriates by building a framework of microfibrils which becomes enveloped by electron-dense material; in addition to this rough-form, in C. intermedia an intracellular smooth layer is formed on the inner and outer side of the stylet. In contrast, the stylet formation of Adenorhynchus balticus (Typhloplanoida), Marirhynchus longasaeta (Kalypthorhynchia), Provortex psammophilus and P. tubiferus (Dalyellioida) occurs synchronously and without a roughform, containing a fibrillar or tubular framework. The stylets in several species of the taxon Promesostoma (Typhloplanoida) are built in a way very similar to that in A. balticus and M. longasaeta, but successively.The fine structural properties known at present and the various formation modes of penial hard structures are discussed from the phylogenetic aspect.

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Abkürzungen ae Atriumepithelzelle - ag Atrium genitale - am Atriummuskulatur - ba Bakterium - bl Basallamina oder vergleichbare Interzellularsubstanz - bm Bulbusmuskulatur - bz Stilettbildungszelle - cw Cilienwurzel - de Ductus ejaculatorius - dr Drüsenrohr - dz Ductuszelle - fz Füllzelle - hd Hemidesmosom - hz Hüllzelle - k Kern einer Stilett- bzw. Nadelbildungszelle - m entstehende Muskulatur - ma Macula adhaerens - mc Muskelzylinder - mf Mikrofibrillen - mv Mikrovilli - n Nerv - nz Nadelbildungszelle - pm äußere Penismuskulatur - rm Ringmuskulatur - s Stilett - sd Septatdesmosom - sg Sekretgangzelle - sgz Sekretgangzelle - skg Spermakornsekretgang - skr Spermakornsekretrohr - sm stilettumhüllende Muskulatur - sn Stilettnadel - sna Stilettnaht - sp Spermium - sz Sekretzelle - vg Vesicula granulorum - vgm Muskulatur der Vesicula granulorum - za Zonula adhaerens     

Primary production data from the south-eastern Weddell Sea

Summary Phytoplankton production for three size classes (<20 m, 20–100 m, >100 m), total primary production and qualitative composition of phytoplankton populations were recorded from 18 stations in the south-eastern Weddell Sea in February/March 1983. Total primary production ranged between 80 and 1670 mg C m^-2 d^-1 with an average of 670 mg C m^-2 d^-1, nearly 70% of which was contributed by the <20 m size fraction (usually pennate and/or centric diatoms). Production of phytoplankton was in the higher range of values reported by other authors for the same region. Variations in primary production could not be attributed to composition of populations, ambient light levels or concentrations of macronutrients (N, P, Si). Phytoplankton populations had a higher diversity in the deeper parts of the Weddell Sea and coincided with different oceanographic situations. Three zones (along the shelf-ice edge from Atka Bay to Halley Bay, west of Halley Bay and off the Filchner/Rønne Ice Shelf) with different communities could be clearly distinguished.     

Animal community structure as a function of stream size

The species-area relationship of the island biogeography theory was calculated for macroinvertebrates in 22 coastal, adjacent streams. A z-value of 0.19 was obtained. The low z-value was probably a consequence of the short distances between streams as well as high dispersal rates. In addition, a cluster analysis based on the dissimilarity of species assemblages showed that stream size was of prime importance in categorizing the streams. To a smaller extent water quality affected the community structure in the streams.     

Anti-predator adaptations in a neustonic insect (Velia caprai)

Summary The risk of a Velia caprai (Heteroptera: Veliidae) individual to fall victim to brown trout (Salmo trutta) was demonstrated experimentally to be markedly lower when several bugs were simultaneously exposed to the trout. V. caprai was found distasteful to brown trout, and a high proportion was ejected alive after being captured. We suggest that school formation in V. caprai lowers the risk of predation because frequent predator-prey encounters may assist in retention of the avoidance learned by the predator. Individual behavioural responses to attacks were variable and the frequency of expansion skating and thanatosis was temperature dependent. Thanatosis postures were either symmetric with the legs pressed to the body or irregular.