Arteriovenous haemofiltration: a recent advance in the management of renal failure.

Twenty five patients with oliguric renal failure were treated by a combination of continuous arteriovenous haemofiltration and intermittent haemodialysis over 18 months. Haemofiltration was given for a mean of 6.6 days and the mean filtration volume was 6.0 1/day. Fourteen of the 25 patients survived beyond two months after the period of oliguria. Haemofiltration proved to be a simple and effective method of fluid removal; it allowed maintenance of stable fluid balance and permitted optimum nutrition during prolonged oliguria.     

Mechanism of degradation of LH-RH and neurotensin by synaptosomal peptidases

The products of degradation of LH-RH and neurotensin by synaptosomes isolated from rat hypothalamus and cortex have been identified. LH-RH is cleaved at Tyr5-Gly6 and Pro9-Gly10 giving rise to LH-RH (1-5), LH-RH (6-10) and LH-RH (1-9). Neurotensin is cleaved at Arg8-Arg9, Pro10-Tyr11 and Ile12-Leu13, giving neurotensin (1-8), neurotensin (1-10), neurotensin (1-12) and neurotensin (9-13) as major products. While most of the peptidase activity is localized in the cytoplasmic fraction, a small but significant proportion is membrane bound. For LH-RH, the specificity of the membrane-bound activity is similar to that in the cytosol fraction; for neurotensin, the membrane fraction preferentially gives rise to the (1-10) and (1-11) peptides. The most potent inhibitors of the LH-RH and neurotensin degrading enzymes in synaptosomes are heavy metal ions (mercury and copper), p-chloromercuribenzoate and 1,10 phenanthroline.     

The R46 site-specific recombination system is a homologue of the Tn3 and gamma delta (Tn1000) cointegrate resolution system

The nucleotide sequence of the R46 site-specific recombination system has been determined. The organization of the recombination gene (perR46) and the site at which it acts (per site), together with the extensive sequence homology displayed with the tnpR genes and res sites of the transposons Tn3 and gamma delta (Tn1000), suggests that they have been derived from a Tn3-like element. These site-specific recombination functions of R46 play a role in plasmid maintenance.     

Olfactory adenylate cyclase of the rat. Stimulation by odorants and inhibition by Ca2+.

The Ca2+-dependent regulation of the activation of myosin MgATPase by vascular-smooth-muscle thin filaments involves caldesmon. This effect may be due to the direct interaction of caldesmon with a Ca2+-binding protein such as calmodulin or phosphorylation of caldesmon by a Ca2+-dependent kinase. I have found that Ca2+ switches on aorta thin filaments in less than 10 s, whereas the caldesmon in the thin filaments is phosphorylated only slowly (half-time greater than 10 min) and the maximum phosphorylation is very low (1 molecule per 7 molecules of caldesmon). I conclude that the phosphorylation of caldesmon hypothesis is untenable.     

Characteristics of environmental isolates of Legionella pneumophila.

Thirty-eight cultures of Legionella pneumophila isolated from surface waters were characterized by their morphological, tinctorial, biochemical, and serological properties and by their ability to produce disease in guinea pigs. Their susceptibility to antimicrobial agents also was tested. When they were compared with clinical isolates, no important differences were found between cultures from the two sources. Sodium hippurate hydrolysis, gelatin liquefaction, pigment formation, and beta-lactamase and alkaline phosphatase activity were useful in differentiating the four described species of Legionella. Hydrolysis of diacetylfluorescein and the inability to reduce nitrate help to distinguish Legionella species from other gram-negative bacterial rods.     

Studies on the structure,ultrastructure and function of the subcommissural organ-reissner's fibre complex of the European eel Anguilla anguilla L.

Summary The Subcommissural organ (SCO) of the European eel consists of tall columnar cells which secrete Reissner's fibre (RF) into the third ventricle and store colloid-like materials of differing electron densities in their hypendymal regions. The cells of the SCO carry large cilia and numerous microvilli.Function of the SCO-RF complex has been investigated by an in situ staining technique using aldehyde fuchsin and by the intracranial injection of ³⁵S-cysteine combined with autoradiography. Osmotic stimuli had no effect on stainability of the complex, though indications were obtained from the autoradiographic studies that it was rendered more active by transferring eels from sea water to fresh water. The effects of changes in background colouration and total illumination were investigated using the in situ technique and it was found that a change from a black background to a white one and from a black background to darkness appeared to stimulate the complex. It is shown that activity of the SCO-RF complex, unlike that of the hypothalamo-neurohypophysial system does not appear to be affected by stimuli that may be regarded as merely stressful.The findings are evaluated and discussed in the light of previous work and it is suggested that the use of radioactive tracers offers the best chance of success in establishing the function of the complex.     

Mating,insemination, and ovulation in the tsetse fly, Glossina morsitans

Virgin females of the tsetse fly, Glossina morsitans orientalis, retain their first egg within the right ovary whereas mated females ovulate. The component of the mating act which causes ovulation and thereby initiates the ovarian cycles which follow, is not insemination, the construction of a spermatophore in the uterus, or a humoral factor associated with the testes, accessory glands or ejaculatory ducts of donor males, or ‘full’ spermathecae of donor females. The ovulation rate increases with copulation time and females are shown to ‘add up’ their ‘sexual experience’ independently of that of the males. Inter-specific matings between G. morsitans and G. austeni also result in ovulation, but an unidentified factor associated with the completion of the mating act was also apparent. It is suggested that a ‘mechanical’ factor probably with nervous and endocrine components is responsible for the release of the egg from the ovary. Observations on the construction of empty spermatophores by aspermic males of G. morsitans are included.     

STARCH IN FUNGI. II. INDUCTION OF AMYLOIDITY IN MEMBERS OF DIVERSE GENERA

Nonamyloid hyphae from fungal fruit bodies which normally produce amyloid structures can be induced to produce starch molecules when incubated in glucose-1-phosphate solution. Hyphae from fruit bodies without natural amyloid structures could not be induced to produce starch. The genes for the starch-synthesizing enzymes are apparently activated when fruit body formation is initiated.     

Growth responses of mycorrhizal and non-mycorrhizal tropical forage species to different levels of soil phosphate

Three tropical forage legumes, Stylosanthes capitata, Pueraria phaseoloides and Centrosema macrocarpum, and one grass, Brachiaria dictyoneura, were grown in a sterile phosphate deficient soil amended with soluble or rock phosphate at rates ranging from 0 to 400 mg kg^-1 soil. The effects of inoculation with Glomus manihotis on mycorrhizal infection and plant growth were assessed. Early growth and nodulation of P. phaseoloides in soil with and without rock phosphate fertilizer were also determined. In the legumes, mycorrhizal infection was high at all P levels and sources, except for a significant decrease of infection in S. capitata at high levels of superphosphate. Plant growth was significantly increased by phosphate fertilizer and mycorrhizal inoculation. Mycorrhizal responses were more pronounced at low P levels with both P sources. In B. dictyoneura mycorrhizal infection was decreased with increasing additions of P. No effects of mycorrhizal inoculation (except with no added P) were observed. Growth and nodulation of P. phaseoloides were greatly stimulated by mycorrhizal inoculation.