Scanning electron microscopy of pulmonary vascular endothelium in rats with hypoxia-induced hypertension

Scanning electron microscopy was used to study the endothelial surface of the pulmonary trunk, artery, and vein in normobaric control rats as well as in rats exposed to hypobaric hypoxia for 7 and 21 days. The individual endothelial cells of the normobaric pulmonary trunk and hilar artery were flat and slightly elongated with elevated nuclear regions, and those of the intermediate-sized artery were more elongated and had more microvilli than the large arteries studied. Their endothelial cell boundaries were outlined by beaded cytoplasmic projections. The surfaces of the normobaric hilar and intermediate-sized veins were smooth and demonstrated numerous longitudinal streaks. These venous endothelial cells were elongated and their cell boundaries were outlined by low discontinuous marginal folds. Exposure to hypobaric hypoxia caused the following changes on the arterial surface: elevation of the endothelial cells; formation of microvilli-rich cell clusters; formation of hollow defects; and the attachment of leukocytes. Hypobaric hypoxia also caused the disappearance of the longitudinal streaks and the occurrence of microvilli-rich cells in the hilar veins. The endothelial surface modifications in the hypobaric rats could be related to thickening of the endothelium, intimal edema, increased intimal connective tissue, luminal invasion of leukocytes, and increased endothelial cell proliferation, known to occur in systemic arteries of hypertensive animals.     

SERGE, the subcellular site of initial hepatic glycogen deposition in the rat: a radioautographic and cytochemical study

Hormonal control of hepatic glycogen and blood glucose levels is one of the major homeostatic mechanisms in mammals: glycogen is synthesized when portal glucose concentration is sufficiently elevated and degraded when glucose levels are low. We have studied initial events of hepatic glycogen synthesis by injecting the synthetic glucocorticoid dexamethasone (DEX) into adrenalectomized rats fasted overnight. Hepatic glycogen levels are very low in adrenalectomized rats, and DEX causes rapid deposition of the complex carbohydrate. Investigation of the process of glycogen deposition was performed by light and electron microscopic (EM) radioautography using [3H]galactose as a glycogen precursor. Rats injected with DEX for 2-3 h and [3H]galactose one hour before being killed displayed an increasing number of intensely labeled hepatocytes. EM radioautography revealed silver grains over small (+/- 1 micron) ovoid or round areas of the cytosome that were rich in smooth endoplasmic reticulum (SER) and contained a high concentration of small dense particles. These distinct areas or foci of SER and presumptive glycogen (SERGE) were most numerous during initial periods of glycogen synthesis. After longer exposure to DEX (4-5 h) more typical deposits of cytoplasmic glycogen were evident in the SERGE regions. Several criteria indicated that the SERGE foci contained glycogen or presumptive glycogen: resemblance of the largest dense particles to beta-glycogen particles in EM; association of 3H-carbohydrate with the foci; removal of particles and label with alpha-amylase; and positive reaction with periodic acid-chromic acid-silver methenamine. The concentration of SER in the small foci and the association of newly formed glycogen particles with elements of SER suggest a role for this organelle in the initial synthesis of glycogen.     

Correlation between limitation of growth ofPachysolen tannophilus on D-xylose with the formation of ethanol and other products

The formation of ethanol, xylitol, ribitol, arabitol and acetic acid from D-xylose byPachysolen tannophilus correlated with the limitation of growth. The correlation was consistent with these products being secondary metabolites.Issued as NRCC Publication Number 24259.     

成人腹泻轮状病毒的提纯及其高价免疫血清的制备

本文采用交叉免疫电泳技术,首先提纯了成人腹泻轮状病毒(Adult DiarrhoeaRotavirus简称:ADRV),并经电镜确认,用作免疫抗原,首次制备了高价兔与豚鼠抗ADRV血清和小鼠抗ADRV腹水,其特异性经交叉免疫电泳和对流免疫电泳鉴定,其效价经酶联免疫吸附试验(ELISA)检测均在1:2,000以上。     

The key role of residue 5 in angiotensin II

The conformation–biological activity relationships in a series of angiotensin II analogs substituted in position 5 were studied. Results indicated that only analogs with β-branched residue in position 5 possess spectral and biological properties identical to that of parent angiotensin II.     

Determination of nanogram quantities of osmium-labeled nucleic acids by stripping (inverse) voltammetry

Modification of nucleic acids with OSO4 in the presence of pyridine results in a formation of a covalently bound electroactive center in a polynucleotide chain detectable by polarographic (voltammetric) methods. It has been shown that DNA modified with osmium (DNA-Os) accumulates at the hanging mercury-drop electrode during a waiting time in a wide range of potentials between 0 and -1.0 V (against the saturated calomel electrode) and produce at neutral pH a well-developed reduction peak at about -1.2 V due to scanning in the cathodic direction. Using the differential-pulse stripping (inverse) voltammetry, nanogram quantities of single-stranded DNA-Os can be determined at relatively short waiting times (1-3 min). Double-stranded DNA is modified with osmium to a much lesser extent as compared to single-stranded polynucleotides. The degree of modification of double-helical DNA is influenced by the presence of single-stranded and distorted double-stranded regions in the DNA molecules and by the environmental conditions which influence the DNA conformation. Osmium can thus be used as a probe of the DNA structure, and a few micrograms of double-helical DNA sample suffice for the voltammetric analysis.     

Age-Related Changes in Aldehyde Dehydrogenase Activity of Rat Brain, Liver, and Heart

Abstract: Aldehyde dehydrogenase (ALDH) activity was measured in brains, livers, and hearts of 23–26-month-old and 3-month-old rats. A significant increase of ALDH activity was found in whole brain of old rats with both acetaldehyde (39%) and propionylaldehyde (15%) used as substrates. In different brain areas of old rats, with acetaldehyde used as substrate, a significant increase of ALDH activity was found in striatum (30–50%) and cerebral cortex (37%). However, no significant difference in ALDH activity was found in livers and hearts of young and old rats. Preliminary experiments showed a significant increase of aldehyde reductase activity (52%) with p -nitrobenzaldehyde used as substrate in whole brain of old rats compared with young rats. The present work indicates that an increase of ALDH activity in brain of old rats may be an adaptive phenomenon.     

Germanium toxicity in selected bacterial and yeast strains

Summary The toxicity of germanium dioxide (GeO₂) to 21 bacterial and 13 yeast strains was investigated in liquid broth medium to obtain information on strains tolerant to high (1 to 2 mg/ml) GeO₂ concentrations.Arthrobacter sp. NRC 32005,enterobacter aerogenes NRC 2926,Klebsiella aerogenes NCTC 418 andPseudomonas putida NRC 5019 were tolerant to 1 mg/ml GeO₂.Bacillus sp. RC607 was able to grow in the presence of 2 mg/ml GeO₂ at pH 10 in broth culture. The yeastsCandida guilliermondii, Candida shehatae andPachysolen tannophilus were the most sensitive to GeO₂ as evidenced by their diminished growth rates at a GeO₂ concentration as low as 0.1 mg/ml. None of the yeast strains tested exhibited growth in the presence of 1 mg/ml GeO₂. The high pH of the medium containing germanium may be partially responsible for the growth inhibition of the yeast cultures. Select bacterial cultures previously exposed to 1 mg/ml GeO₂ could tolerate and grow better at 2 mg/ml GeO₂, suggesting the existence of very efficient adaptive mechanisms. The pH of the medium could modulate GeO₂ tolerance and this effect was found to be strain-dependent.