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Biomedical subjects

M Salas

Publications and source records attributed to M Salas.

At least 307 records · Page 17Linked to original sources
PubMed1976

Effect of cerium on the rat liver: an ultrastructural and biochemical study.

In rats, liver steatosis and necrosis were induced by cerous chloride (CeCl3) and the evolution of these changes was examined. By electron microscopy, 17 hours after CeCl3 treatment, dilation, disorganization and degranulation of the rough endoplasmic reticulum (RER) were noted with an increase in the number and electron density of lysosome-like bodies. In addition, nuclear chromatin showed showed a marked focal electron density, and the nuclear membrane appeared to be interrupted. At 24 hours, the RER was markedly dilated and degranulated, with free ribosomes aggregated in the cytoplasm. The Golgi cisternae appeared to be empty. There was an increase in the number and size of lipid droplets, with depletion of glycogen. At 48 hours, a massive proliferation of smooth endoplasmic reticulum (SER) vesicles occurred. Large lipid droplets were scattered throughout the cytoplasm, while the mitochondria displayed mild changes. By the 8th day, the number of lipid droplets returned to normal; no abnormalities were detected in the other cell organelles. Biochemically, the total hepatic ATP levels fell significantly by the 12th hour, dropping to a minimum by the 48th hour. The liver was gradually depleted of glycogen within the first 48 hours, while hepatic triglycerides increased rapidly, reaching a peak at 96 hours. Exogenous administration of adenine, ATP (adenosine triphosphate), or tryptophan completely prevented CeCl3-induced mortality; hepatic fat accumulation and necrosis were markedly decreased. Glucose, dl-methionine, and choline had no protective effect. It appears that a defect in hepatocellular lipoprotein synthesis and/or release may be responsible for lipid accumulation.

Adenine↗
PubMed1976

Transcription in vitro of phi29 DNA and EcoRI fragments by Bacillus subtilis RNA polymerase.

EcoRI fragments A, B and C produced from linear phi29 DNA, but not D or E fragments, are transcribed by purified Bacillus subtilis RNA polymerase. The transcription of fragments A and C is initiated preferentially with GTP and to a lesser extent with ATP; the reverse happens in the case of fragment B. The dinucleotides GpU and GpA respectively, compete specifically with the incorporation of [gamma-32P]GTP directed by fragments A and C. The RNA synthesized in vitro by purified B. subtilis RNA polymerase is highly asymmetric. Most of the RNA synthesis directed by fragments A and C is early RNA. However, most of the RNA produced by fragment B is anti-late-RNA. Addition of crude extracts inhibit the transcription of fragment B but not that of fragments A and C.

Bacillus subtilis↗
PubMed1976

Genetic analysis of bacteriophage phi 29 of Bacillus subtilis: integration and mapping of reference mutants of two collections.

Reference mutants of Bacillus subtilis phage phi 29 of the Madrid and Minneapolis collections were employed to construct a genetic map. Suppressor-sensitive and temperature-sensitive mutants were assigned to 17 cistrons by quantitative complementation. Three-factor crosses were used to assign an unambiguous order for the 17 cistrons. Recombination frequencies determined by two-factor crosses were used to construct a linear genetic map of 24.4 recombination units. The genes were numbered sequentially from left to right (1 to 17) according to their relative map position.

Bacillus subtilis↗
PubMed1976

Effect of praseodymium nitrate on hepatocytes and Kupffer cells in the rat.

Intravenous administration of the rare earth metal salt, praseodymium nitrate, induced hepatic damage in the rat, as assessed by morphologic examination (light and electron microscopy) and biochemical parameters (serum glutamic-pyruvic transaminase (EC 2.6.1.2) and glutamic-oxalacetic transaminase (EC 2.6.1.1) activity as well as hepatic triglyceride content). Praseodymium hepatotoxicity was only attained with lower doses (10, 20, or 40 mg/kg), whereas a larger dose (80 mg/kg) was inactive in this respect. As detected by electron microscopy, lower doses of the metal salt caused hepatocytic alterations consisting of degranulation and dilatation of rough endoplasmic reticulum, accumulation of smooth endoplasmic reticulum as well as numerous lipid droplets. No abnormalities were detected in the cell organelles following administration of a large dose of the metal salt; however, vacuoles containing markedly electron-dense material were seen in the cytoplasm of the hepatocytes and the sinusoidal Kupffer cells.

Alanine Transaminase↗
PubMed1976

Microsomal enzyme inducers and hypervitaminosis A in rats.

Pretreatment of rats with pregnenolone-16alpha-carbonitrile (PCN) completely prevented the osseous lesions produced by vitamin A overdosage, whereas pretreatment with phenobarbital or with phenytoin (diphenylhydantoin) provided only partial prophylaxis. These microsomal enzyme inducers also decreased vitamin A concentration in the liver and seemed to protect against hypervitaminosis A by enhancing the metabolism of the vitamin. Electron microscopy of the liver showed large, vitamin A-storing perisinusoidal cells. The number, size, and lipid content of these cells were decreased in rats treated simultaneously with vitamin A and PCN, but not in rats pretreated with phenobarbital or phenytoin. Vitamin A, given alone, produced moderate accumulation of smooth endoplasmic reticulum (SER) in hepatocytes, without accelerating microsomal drug-metabolizing enzyme activity; phenobarbital, phenytoin, and PCN also elicited SER accumulation, particularly when administered with vitamin A.

Animals↗
PubMed1975

Synthesis in vitro of phi29-specific early proteins directed by phage DNA.

The RNA and proteins synthesized in an Escherichia coli cell-free system of protein synthesis directed by Bacillus subtilis phage phi29 DNA were studied. Hybridization-competition experiments showed that most of the RNA species synthesized in vitro are early RNAs. Many of the early proteins induced after phage infection were also synthesized in the E. coli cell-free system. None of the late proteins, structural or non-structural, were synthesized in the system in vitro.

Bacillus subtilis↗
PubMed1975

Experimental pathology of aging.

We have been concerned in the first section of this review with those diseases that are aging processes, or appear to be so. Some of these (e.g., cardiovascular, pulmonary, neoplasia) cause the death of a large proportion of animals, while others (e.g., osteoporosis, amyloidosis), though clearly progressive with age, are nonfatal. Many diverse factors influence the normal process of aging. Restriction of dietary caloric intake prolongs lifespan and decreases the incidence and severity of diseases associated with aging, probably by depressing anterior pituitary gland function...

Aging↗