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J Suter

Publications and source records attributed to J Suter.

11 recordsLinked to original sources
PubMed1990

Increase in hepatocyte and nuclear volume and decrease in the population of binucleated cells in preneoplastic foci of rat liver: a stereological study using the nucleator method.

Gamma-glutamyltranspeptidase-positive hepatocyte foci were produced in female rats given a single dose of diethylnitrosamine neonatally after birth and, after weaning, a diet containing phenobarbitone for 30 wk. The nucleator method, a new stereological approach, provided an efficient, unbiased estimate of mean cell volume in focal lesions and extrafocal areas. It also provided an unbiased sample of cells to estimate hepatocyte nuclear volume and the percentage of binucleated cells. The results showed an increase in the mean volume of mononucleated cells--from 4,700 micron3 in extrafocal areas to 12,700 micron2 in foci--and of binucleated cells--from 6,900 micron3 to 25,000 micron3. This demonstrated the hypertrophic effect of the carcinogenic treatment in focal lesions. A striking reduction in the proportion of binucleated cells was also observed in the preneoplastic lesions. Nuclear volume measurements from mononucleated and binucleated hepatocytes were used to assess ploidy. An apparent increase in nuclear ploidy, with no change in cellular ploidy, was noted in focal tissue when compared with nonfocal tissue. This appeared to be caused by an increase in mononucleated tetraploid cells and a reduction in binucleated cells with two diploid nuclei, indicating an altered mitotic mechanism in focal lesions. The significance of these changes in cell volume, apparent ploidy levels and binuclearity in preneoplastic foci is discussed in relation to the hepatocarcinogenic process.

Animals↗
PubMed1990

Ultrastructural changes in chemically induced preneoplastic focal lesions in the rat liver: a stereological study.

Ultrastructural changes were investigated and quantified, using a stereological approach, in early gamma-glutamyltranspeptidase (GGT)-positive focal lesions, induced in the rat liver by treatment with a single initiating dose of diethylnitrosamine (DENA) followed by promotion with phenobarbitone (PB) for 30 weeks. Within the extra-hepatocyte environment of focal tissue, the mean volume occupied by Ito cells was markedly decreased, whilst that occupied by endothelial and Kupffer cells was increased, when compared to uninvolved tissue from the same rat livers. The bile canaliculi were dilated, but no significant differences in the mean volume occupied by the sinusoidal and Disse spaces were noted. In focal hepatocytes there was a striking overproduction of lipid droplets and proliferation of smooth endoplasmic reticulum (sER). Whorls of concentrically arranged, parallel ER membranes were found only in the hepatocytes of preneoplastic foci, in association with the proliferated sER, and never in the surrounding, uninvolved tissue. The increase in mean volume of the sER, lipid droplet and cytoplasmic matrix compartments, together with the appearance of whorls, were the major contributing factors to the marked hypertrophy seen in focal hepatocytes. The mean volume of the rough endoplasmic reticulum, mitochondrial, lysosomal, peroxisomal and nuclear compartments per hepatocyte also increased, but contributed to a lesser extent to the cellular hypertrophy. It is speculated that whorls may be structural adaptations, resulting from a possible alteration in the normal feedback control of cholesterol synthesis, for the production of sterols and the biogenesis of sER in eosinophilic-type focal cells. The significance of changes observed in focal tissue, and the high biological variation noted between foci, is discussed in relation to the hepatocarcinogenic process.

Animals↗
PubMed1988

Adjustment of the myelin sheath to axonal atrophy in the rat spinal root by the formation of infolded myelin loops.

Atrophy of the L4 dorsal and ventral spinal roots was experimentally induced by unilateral sciatic neurectomy in groups of young (2 and 4 months) and older (12 months) albino rats. During the 4 months following neurectomy, the occurrence of infolded myelin loops (IMLs) was quantitatively examined in transverse sections prepared using perfusion fixation with glutaraldehyde and embedding in epoxy resin. The number of IMLs was higher on the operated side and increased with the time of survival and the age of the animals. The formation of IMLs is a characteristic early response of a large-caliber myelin sheath to axonal atrophy, probably reflecting the presence of redundant myelin.

Aging↗
PubMed1986

Evaluation of the bactericidal activity of beta-lactam antibiotics on slowly growing bacteria cultured in the chemostat.

The bactericidal activity of 23 beta-lactam antibiotics was compared in slowly growing bacteria cultured in a chemostat. In an attempt to mimic possible in vivo conditions, slowly growing cultures were produced by limitation of iron, glucose, phosphate, or magnesium. Only select antibiotics remained effectively bactericidal against slowly growing cells. For these compounds, the rate of antibiotic-induced loss of viability was a constant when killing was expressed per generation (in contrast to absolute time) in that slowly growing bacteria were killed proportionately more slowly. Individual antibiotics differed greatly, however, in their specific bactericidal activities against slowly growing cells, i.e., in the absolute degree of killing elicited during exposure of the bacteria to MIC equivalents of the drugs. Specific bactericidal activities varied not only with drug structure but also with the bacterial strains and, to a lesser extent, with the nature of the growth-limiting nutrient. In slowly growing cultures exposure to the low drug concentrations studied here (near MIC) caused killing without detectable lysis. Antibiotics with high specific bactericidal activities were capable of rapidly killing cultures of slowly growing pathogens despite extremely long generation times approaching those reported for in vivo growth rates.

Anti-Bacterial Agents↗
PubMed1985

Staphylococci, in vitro and in vivo.

Strains of Staphylococcus aureus were grown in broth and by the membrane technique; both drug-free media and media containing cloxacillin were used. The staphylococci grown in broth containing cloxacillin showed one thick cross wall and were larger than those grown in drug-free broth: 1.6 micron in diameter as opposed to 0.9 micron. The staphylococci grown on membranes placed on agar containing cloxacillin were 2-3 microns in diameter and contained three or more cross walls. Mice were infected intraperitoneally with staphylococci. After treatment with cloxacillin, the peritoneal fluid and spleens contained staphylococci that were 2-3 microns in diameter with three or more cross walls. A staphylococcal endocarditis was induced in rabbits that were then treated with cloxacillin. The staphylococci in the vegetation of the treated rabbits were 2-3 microns in diameter and contained multiple cross walls. Large staphylococci with multiple cross walls were observed in specimens from patients with respiratory infections treated with beta-lactam antibiotics. It appears, therefore, that the ultrastructure of staphylococci in vivo is comparable to that of staphylococci grown on a solid support medium such as a membrane, and different from that of staphylococci grown in a liquid medium.

Animals↗
PubMed1977

[Criteria for determining whether to offer compensation in cases of whiplash injury to the spine (neck area). A study of cases in which compensation or cash settlement has been granted (author's transl)].

We compared two groups of patients with whplash injury. The first group of 17 patients received a life annuity or a cash settlement, whereas the second group, comprised of 84 people, received no compensation at all. This comparison revealed some considerable differences. However, with regard to statistically significant factors, the 2 groups differ only in neurological symptoms, giddiness, and degenerative changes revealed by X-ray. In the first group, 11 patients who received compensation showed two of the statistically significant factors; 5 patients showed one factor; and 1 showed none. The criteria which govern the granting of compensation are being discussed in detail on the basis of our own cases and the literature. It is an exception when permanent damage due to whiplash is accepted. In individual cases, however, continuous complaints and objective findings years after the trauma are justification for a moderate compensation.

Adult↗
PubMed1977

The proliferative response of hepatic peroxidomes of neonatal rats to treatment with SU-13 437 (nafenopin).

The repeated administration of the hypolipidemic agent Su-13 437 (nafenopin) to neonatal rats roughly doubled the number of peroxisomes in the liver tissue and caused a sixfold volumetric expansion of the peroxisomal compartment. During the proliferative response, the size-distribution of the peroxisomes was reversibly altered, enlarged particles appearing in numbers varying according to the dose given. By means of a new method for quantitative autoradiography, it was shown that (a) the concentration of silver grains over peroxisomes was comparable to that found over the endoplasmic reticulum; (b) the peak incorporation of [3H]arginine into the peroxisomes was dealyed in comparison with that into the endoplasmic reticulum; (c) the label, once incorporated into the expanding peroxisomal compartment, displayed the same shift to large particles as did the whole population. These results are compatible with the biosynthetic pathway for peroxisomal catalase proposed earlier (cf. reference 12), and with the notion that the drug-induced size-shift might have resulted from progressive growth of a particular class of peroxisomes formed in the presence of the agent. Evidence is presented to show that during the recovery period the larger peroxisomes are removed preferentially.

Animals↗