Age-related changes in the morphology and function of the zona glomerulosa of the rat adrenal cortex

The age-related changes in the morphology and function of rat adrenal zona glomerulosa (ZG) were investigated by coupled stereological and radioimmunological techniques. For this purpose 4-, 8-, 16- and 24-month-old rats were studied. Aging caused a notable lowering in the plasma aldosterone concentration and a marked decrease in both basal and ACTH- or angiotensin II (ANG-II)-stimulated secretion of collagenase-dispersed ZG cells. Plasma renin activity (PRA) underwent an age-dependent decrease, while the plasma level of ACTH displayed a significant rise. ZG and its parenchymal cells did not evidence any age-related morphologically demonstrable alteration in their growth, nor ZG cells showed any marked ultrastructural change, with the exception of a severe lipid-droplet repletion. This last finding is in keeping with the aging-induced decrease in the secretory activity of ZG cells, inasmuch as lipid droplets are the intra-cellular stores of cholesterol esters, the obligate precursors of steroid hormones in rat adrenals. ACTH and ANG-II are well known to be involved in the maintenance of the growth of rat ZG; thus, the combined impairment of ANG-II production (as evidenced by PRA lowering) and increase in ACTH secretion may maintain unchanged ZG growth during aging.     

Influence of acclimation and determination temperature on the oxygen consumption of the brain in two species of anurans

1. 1. The effects of sudden changes by increasing or decreasing the measurement temperature on the oxygen consumption of the brains of Bufo arenarum and Leptodactylus ocellatus were determined.

2. 2. The experiments were carried at in vitro at temperatures which range from 4 to 37°C. The brain was oxygenated and stabilized for 20 min at each of the temperatures to which it was subjected before oxygen consumption measurements were made.

3. 3. A theoretical curve representing the variation of oxygen consumption with temperature was calculated according to the following exponential relationship; for Leptodactylus ocellatus y = 0.408 × 1.07^x and for Bufo arenarum y = 0.389 × 1.065^x.

4. 4. These results were compared with the brain oxygen consumption of animals acclimated to different temperatures, whose oxygen consumption was measured at a fixed temperature. Only Leptodactylus ocellatus had a significantly lower oxygen consumption in a high range of temperatures, indicating thermal compensation, probably to save metabolic reserves.

5. 5. No deterioration of the brain tissue was observed, as several passages from high to low temperatures in the range of 20°–30°C, showed a reversible oxygen consumption in acclimated and non-acclimated Bufo arenarum and Leptodactylus ocellatus.

Study of the interaction of polyols with polymers containing n-substituted [(4-boronophenyl)methyl]-ammonio groups

Polymers, based on dextran and cellulose, having 2-{[(4-boronophenyl)-methyl]-ethylammonio}ethyl and -diethylammonio～ethyl groups were prepared. It was shown that these polymers could be employed for absorption of cis-diol compounds. The polymers were found to be highly specific towards polyols, carbohydrates, nucleosides, and nucleotides over a wide range of pH. The polymer based on DEAE-Sephadex A-25 was used in separating nucleosides, and in fractionating mononucleotides and carbohydrates. The chromatographic behavior of carbohydrates is defined by their structure and conformation, which are also responsible for different stabilities of the boronic complexes generated.     

Prostaglandins and renal function II. The effect of prostaglandin inhibition on autoregulation of blood flow in the intact kidney of the dog

In order to evaluate the effect of prostaglandin release on renal autoregulation in the intact kidney of the dog, pressure-flow curves were obtained before and after the administration of either indomethacin or meclofenamate, two potent prostaglandin synthetase inhibitors. After drug administration renal venous prostaglandin E decreased in each of eight studies with a mean change from 286 to 141 pg/ml (p < .001). In addition, prostaglandin inhibition was associated with a 31 percent decrease in renal blood flow and a 58 percent increase in renal resistance. Yet, as renal perfusion pressure was decreased by aortic constriction, the change in flow per pressure reduction and the percent change in renal resistance were not significantly different after prostaglandin inhibition when compared to control values in the same animals. The magnitude of the pressure range over which autoregulation was maintained was also similar in the two groups although both the initial and lowest level of autoregulation were slightly higher after prostaglandin inhibition. It is concluded that the administration of these prostaglandin synthetase inhibitors does not significantly impair renal autoregulation in the intact dog kidney.     

Optimising Immunogenicity with Viral Vectors: Mixing MVA and HAdV-5 Expressing the Mycobacterial Antigen Ag85A in a Single Injection

The Bacillus Calmette - Guerin (BCG) vaccine provides a critical but limited defense against Mycobacterium tuberculosis (M.tb). More than 60 years after the widespread introduction of BCG, there is an urgent need for a better vaccine. A large body of pre-clinical research continues to support ongoing clinical trials to assess whether viral vectors expressing M.tb antigens that are shared by BCG and M.tb, can be used alongside BCG to enhance protection. A major focus involves using multiple unique viral vectors to limit anti-vector immunity and thereby enhance responses to the insert antigen delivered. The successful introduction of viral vector vaccines to target M.tb and other pathogens will be reliant on reducing the costs when using multiple vectors and inhibiting the development of unwanted anti-vector responses that interfere with the response to insert antigen. This study examines methods to reduce the logistical costs of vaccination by mixing different viral vectors that share the same insert antigen in one vaccine; and whether combining different viral vectors reduces anti-vector immunity to improve immunogenicity to the insert antigen. Here we show that a homologous prime-boost regimen with a mixture of MVA (Modified Vaccinia virus Ankara) and Ad5 (human adenovirus type 5) vectors both expressing Ag85A in a single vaccine preparation is able to reduce anti-vector immunity, compared with a homologous prime-boost regimen with either vector alone. However, the level of immunogenicity induced by the homologous mixture remained comparable to that induced with single viral vectors and was less immunogenic than a heterologous Ad5 prime-MVA-boost regimen. These findings advance the understanding of how anti-vector immunity maybe reduced in viral vector vaccination regimens. Furthermore, an insight is provided to the impact on vaccine immunogenicity from altering vaccination methods to reduce the logistical demands of using separate vaccine preparations in the field.     

Effect of antioxidants on the genetic stability of cryopreserved mint shoot tips by encapsulation–dehydration

The effect of antioxidants applied in one step of a cryopreservation protocol by encapsulation–dehydration on recovery and genetic stability of mint shoot tips has been studied. Glutathione (0.16 or 0.24 mM), ascorbic acid (0.28 or 0.43 mM) and α-tocopherol (vitamin E) were added to the preculture medium (0.3 M sucrose). DNA was extracted from three different types of samples: leaves from shoots, callus at the base of shoots and callus. RAPD and AFLP markers were used to assess the genetic stability. The use of antioxidants did not improve recovery after cryopreservation. One of the genotypes, ‘MEN 198’, showed higher percentage of stable samples than the other one, ‘MEN 186’ (56 vs. 37?%; considering all treatments and types of explant). The use of vitamin E improved the percentage of stable samples with respect to control treatment (no antioxidant) in ‘MEN 186’. No differences in the percentages of stable samples were observed among cryopreserved and non-cryopreserved (treated similarly without immersion in liquid nitrogen) plant material. Recovered shoots of both genotypes showed higher stability (76–80?% stable samples) than callus samples (14–22?%).     

Plasmid transformation of Ruminococcus albus by means of high-voltage electroporation

To apply recombinant DNA techniques to the genetic manipulation of cellulolytic ruminal bacteria, a plasmid vector transformation system must be available. The objective of this work was to develop a system for plasmid transformation of Ruminococcus albus. Using high voltage electrotransformation, pSC22 and pCK17 plasmid vectors, derived from lactic acid bacteria plasmids and replicating via single-stranded DNA intermediate, were successfully introduced into three freshly isolated R. albus strains and into R. albus type strain ATCC 27210. The optimization of the electrotransformation condition raised the electroporation efficiency up to 3 x 10(5) transformants per microgram of pSC22 plasmid.