Action of neurotensin on size, composition, and growth of pancreas and stomach in the rat

Since the gastrointestinal peptide neurotensin has a stimulatory effect on the secretion of the exocrine pancreas and an inhibitory effect on secretion and motility of the stomach, we investigated whether chronic parenteral administration of neurotensin would affect pancreatic and gastric growth. We therefore infused synthetic neurotensin subcutaneously (dose, 43 and 282 pmol X kg-1 X min-1) in 20 Wistar rats for 2 weeks using Alzet osmotic minipumps and compared pancreatic weight, DNA, RNA, protein, lipase, amylase, pancreatic polypeptide and insulin with these parameters in 10 control rats from the same litter with subcutaneously implanted plastic cylinders approximately the size of the minipumps. In another experiment, synthetic neurotensin (836 pmol X kg-1) was injected intraperitoneally three times a day for 3 days in 12 rats. Thereafter, we measured pancreatic DNA and in vitro incorporation of [3H]thymidine into pancreatic DNA. These effects were compared with the actions of caerulein and normal saline. Long term infusion of the high neurotensin dose induced an increase of pancreatic weight (control: 0.87 g, neurotensin: 1.02 g) and of DNA (control: 2.5 micrograms; neurotensin: 3.5 micrograms) and pancreatic polypeptide (control: 2.4 ng; neurotensin: 7.4 ng) contents, whereas pancreatic protein, RNA, amylase and lipase contents were not stimulated. In relation to DNA, these parameters even were significantly depressed. Insulin remained unchanged. Intraperitoneal injection of neurotensin induced an increase of pancreatic DNA content and stimulated [3H]thymidine incorporation into DNA (control: 11 000 dpm/g; neurotensin: 15 800 dpm/g pancreas). Moreover, long-term neurotensin infusion with the high dose led to a rise in protein concentration and an increase in the thickness of the gastric antrum; antral DNA concentration was insignificantly stimulated. Parenteral neurotensin in the doses and at the times administered, led therefore, to hyperplasia of the pancreas and induced growth of the gastric antrum. It is concluded that neurotensin can act as a trophic factor on pancreas and gastric antrum of the rat. It remains to be determined whether this represents a physiological effect of neurotensin.     

The primary structure of hemoglobin from amur-leopard (Panthera pardus orientalis)

The complete amino acid sequence of the major component of hemoglobin from amur-leopard (Panthera pardus orientalis) is presented. The major component accounts for more than 90% of the total hemoglobin. Separation of the globin subunits was achieved by ion-exchange chromatography on CM-cellulose in urea. The sequence was studied by automatic Edman degradation of tryptic and hydrolytic peptides. Alignment was carried out with human hemoglobin sequence. The NH₂ terminus is blocked with Ac-serine. The data are compared with other mammalian hemoglobins and results are discussed with respect to sequence and physiology.85th communication on hemoglobin.     

Identification and isolation of the primary aggregation factor from the cell membrane of the sponge Geodia cydonium

Summary The primary aggregation factor (pAF) of sponge cells is a glycoprotein that is firmly associated with the cell membrane. Polyspecific antibodies (anti-GM) prepared from sera raised against membranes of cells from the siliceous sponge Geodia cydonium were found to inhibit initial aggregation of homologous cells. The inhibition of aggregation, caused by anti-GM was neutralized by pAF. The pAF had been successfully solubilized and enriched by affinity chromatography, gel filtration and density gradient centrifugation, if checked by polyacrylamide gel electrophoresis in the presence of urea. The M_r of the native pAF was approximately 40 000 as estimated by gel filtration; under denaturing conditions three protein species (M_r: 16 500, 15 500 and 13 500) were identified in the pAF preparation. The pAF was precipitable by Ca⁺⁺ and did not cross-react with antisera against homologous purified secondary aggregation factor and lectin. It is mainly composed of protein (48.0%) and carbohydrate (50.2%). The isolated pAF restored the aggregation potency not only of factor-depleted Geodia cells but also of cells from other Demospongiae. However, the pAF displayed no aggregation enhancing effect on urea-treated cells from species belonging to the Calcispongiae or Hexactinellida. We hypothesize that in contrast to the secondary aggregation, the initial aggregation of Geodia cells is mediated by the one-component system, the bivalent and bifunctional pAF.     

Mucopolysaccharidosis-like alterations in cardiac valves of rats treated with tilorone

The purpose of this study was to examine whether the aortic and mitral valves of rats are involved in the mucopolysaccharidosis-like disorder induced by tilorone. Rats were treated with large doses of the drug for periods of 1-21 weeks. After chronic drug treatment the leaflets of both heart valves were thickened and opaque. In all treated animals the spongiosa layer of the stroma was crowded with vacuolated cells; the fibrosa layer was altered only after prolonged treatment. Ultrastructurally, the vacuolated cells of the spongiosa could be identified as histiocytes and fibroblasts, the former being the most susceptible cell type. The fibroblasts of the fibrosa represented the least sensitive cell type. The histochemical results showed that the clear cytoplasmic vacuoles in the spongiosa cells were due to lysosomal storage of polyanionic material with staining characteristics similar to cartilage matrix. After discontinuation of drug treatment the alterations persisted for several weeks. The present study shows that heart valves are involved in the mucopolysaccharidosis-like disorder induced by tilorone. The molecular pathomechanism of the disorder and the exact identification of the storage material must await further analysis.     

DNA sequence of the coding region of the HLA-B44 gene

An HLA-B44 cDNA clone was identified in a cDNA library constructed from an HLA-B44 homozygous cell line. The DNA sequence was determined and was found to contain the complete coding sequence but for (probably) the three N-terminal codons. Comparisons of the derived amino acid sequence with other HLA-A and -B locus amino acid sequences revealed four HLA-B44-specific substitutions including a new polymorphic site. Regions of strong sequence conservation for HLA-B-locus products were found at the nucleotide and amino acid levels.     

Effect of cell recycle on continuous butanol-acetone fermentation with Clostridium acetobutylicum under phosphate limitation

Summary An overflow filtration unit for cell recycle with Clostridium acetobutylicum was developed. A cellulose-triacetate ultrafiltration membrane with a cut-off volume of 20 000 MW was found to work best. C. acetobutylicum was grown in continuous culture under phosphate limitation (0.74 mM) at a pH value of 4.4 with cell recycle, the cell dry weight in the culture vessel reached 13.1 g/l at a dilution rate of D=0.10 h^-1 and 37°C. 377 mM of glucose were fermented to 190 mM butanol, 116.2 mM acetone and 25.8 mM ethanol. Total acids were 47.6 mM. The butanol productivity was 1.41 g/l/h. At a dilution rate of 0.40 h^-1 the butanol productivity was increased to 4.1 g/l/h but glucose consumption was decreased to 285 mM and butanol, acetone and ethanol production to 138.2, 97.5, 16.5 mM, respectively.     

Pyrococcus furiosus sp. nov. represents a novel genus of marine heterotrophic archaebacteria growing optimally at 100°C

Ten strains representing a novel genus of marine thermophilic archaebacteria growing at between 70 and 103°C with an optimal growth temperature of 100°C and a doubling time of only 37 min were isolated from geothermally heated marine sediments at the beach of Porto di Levante, Vulcano, Italy. The organisms are spherical-shaped, 0.8 to 2.5 m in width and exhibit monopolar polytrichous flagellation. They are strictly anaerobic heterotrophs, growing on starch, maltose, peptone and complex organic substrates. Only CO₂ and H₂ could be detected as metabolic products, the latter being inhibitory to growth at high concentrations. Hydrogen inhibition can be prevented by the addition of S^o, whereupon H₂S is formed in addition, most likely as the result of a detoxification reaction. The GC-content of the DNA of isolate Vc 1 is 38 mol%. The new genus is named Pyrococcus, the fireball. Type species and strain is Pyrococcus furiosus Vc 1 (DSM 3638).     

Formation of plastocyanin and cytochrome c-553 in different species of blue-green algae

Fifteen species from different genera of blue-green algae have been examined for their formation of plastocyanin (PC) and cytochrome c-553 (cyt c-553) in high or low Cu media. In addition to species which contain only cyt c-553 and those which completely exchange their cyt c-553 by PC, a new regulatory type was detected in which this exchange was incomplete. By comparing different species, it could be shown that either this incomplete exchange of cyt c-553 by PC as well as lack of PC in some other blue-green algae is not caused by restricted Cu uptake but is due to different biosynthetic and regulatory properties. Occurrence of PC and cyt c-553 cannot be used as a taxonomic criterium to classify blue-green algae. However, formation of either one or both of these redox components fits well into a line of evolution of the photosynthetic apparatus from the blue-green algae via green algae to higher plants.Abbreviations PC plastocyanin; cyt c-553, cytochrome c-553