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Biomedical subjects

E Fox

Publications and source records attributed to E Fox.

At least 127 records · Page 7Linked to original sources
PubMed1984

The use of methylmethacrylate cement as an instantaneous fusion mass in posterior cervical fusions: a canine in vivo experimental model.

The authors previously predicted the failure of posterior cervical fusions utilizing methylmethacrylate cement as an instantaneous "fusion" mass, based on research using an in vitro canine experimental model. This report describes the results of in vivo canine studies on the same subject. Three groups of dogs had application of a posterior C4-C5 20-gauge cerclage wire and autologous iliac crest bone graft; application of a posterior C4-C5 20-gauge cerclage wire and methylmethacrylate cement; or application of a C4-C5 20-gauge cerclage wire only. This group represented the control group. The dogs were allowed to live for 3 months postoperatively, at which time they were killed and their spine fusions studied radiologically, mechanically, and histologically. Five of the bone fusions united solidly radiologically. Their flexion stability was statistically superior to the others. Histologic studies confirmed solid union of the fusion mass to the underlying bone. Four of the six methylmethacrylate fusions demonstrated cerclage wire fracture and methacrylate-bone separation by the second postoperative month. At the time the dogs were killed, their flexion stability was statistically inferior to the bone fusions and tended to be inferior to the controls as well. Histologically, fibrous tissue was noted to have grown between the methacrylate "fusion" mass and the underlying bone. This work provides a mechanical explanation for the well-known success of the traditional bony fusion. It further supports our original prediction regarding the failure of methylmethacrylate "fusions."

Animals↗
PubMed1983

Isolation of Yersinia enterocolitica from pigs in the United Kingdom.

A survey of the incidence of Yersinia enterocolitica from pigs in the United Kingdom was carried out by two laboratories using pre-enrichment culture methods on colon/caecal contents, faeces and tonsil tissue. Altogether 1931 specimens were cultured and 112 strains of Y enterocolitica were isolated. Only two strains were related to biotype 4, human serotype O:3 and none to biotype 2, human serotype O:9. All other isolates belonged to biotype 1. Many serotypes were identified, the predominant ones being O:6 (30) and O:5 (15) but 41 strains could not be serotyped. Possible reasons for the low incidence of serotype O:3 are discussed.

Animals↗
PubMed1983

The action of insulin on hepatic fructose 2,6-bisphosphate metabolism.

The inhibition of hepatocyte 6-phosphofructo-1-kinase by glucagon was suppressed by insulin when the enzyme was measured in crude extracts. However, no effect of either hormone was observed after the removal of allosteric effectors from the enzyme, suggesting that the alterations in activity may be due to changes in the level of fructose 2,6-bisphosphate, a potent allosteric activator of the enzyme. Insulin opposed the action of both glucagon and exogenous cyclic AMP to lower fructose 2,6-bisphosphate levels. The concentration of glucagon and of cyclic AMP that gave a half-maximal decrease in fructose 2,6-bisphosphate levels was increased in the presence of 10 nM insulin from 0.03 to 0.09 nM and from 12 to 36 microM, respectively. Insulin also counteracted the effect of maximal concentrations of epinephrine on fructose 2,6-bisphosphate levels. In the presence of 0.02 nM glucagon or 10 microM epinephrine, 10 nM insulin enhanced 6-phosphofructo-2-kinase and decreased fructose 2,6-bisphosphatase activity in (NH4)2SO4-treated hepatocyte extracts. The bifunctional enzyme 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase was shown to be a substrate for the cAMP-dependent protein kinase but not for phosphorylase kinase. It was concluded that insulin opposed the action of glucagon and epinephrine by affecting the phosphorylation state of 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase. Fructose 2,6-bisphosphate levels were decreased in liver cells from diabetic rats. Addition of 30 mM glucose elevated fructose 2,6-bisphosphate levels in cells from fed and 24-h-starved rats but not in cells from diabetic rats. This was probably due to decreases in both 6-phosphofructo-2-kinase and glucokinase activity in the diabetic state. These results show that insulin has both short and long term effects on fructose 2,6-bisphosphate metabolism in liver.

Animals↗
PubMed1983

Gonadal hormone activation of male courtship ultrasonic vocalizations and male copulatory behavior in castrated male deer mice (Peromyscus maniculatus bairdi).

The influence of testosterone (T), a 5 alpha-reduced metabolite of T, dihydrotestosterone, and an aromatized metabolite of T, estradiol, on 35-kHz ultrasonic calling and male copulatory behavior by male deer mice (Peromyscus maniculatus bairdi) was examined. Daily treatment with testosterone propionate (TP), dihydrotestosterone propionate (DHTP), or estradiol benzoate (EB) restored male ultrasonic calling in long-term castrated males. Both TP and DHTP restored male copulatory behavior, but EB was ineffective in facilitating copulation. Synergism of EB and DHTP action was observed; when subthreshold doses of EB (1 microgram/day) and DHTP (50 micrograms/day) were administered in combination, male ultrasonic calling and male copulatory behavior were activated. In relation to other comparative findings, these results indicate that the degree to which male sexual behavior is facilitated by 5 alpha-reduced androgens and/or estrogens is influenced by the species and the particular pattern of masculine behavior under consideration.

Animals↗
PubMed1982

Regulation of rat liver fructose 2,6-bisphosphatase.

An enzyme activity that catalyzes the hydrolysis of phosphate from the C-2 position of fructose 2,6-bisphosphate has been detected in rat liver cytoplasm. The S0.5 for fructose 2,6-bisphosphate was about 15 microM and the enzyme was inhibited by fructose 6-phosphate (Ki 40 microM) and activated by Pi (KA 1 mM). Fructose 2,6-bisphosphatase activity was purified to homogeneity by specific elution from phosphocellulose with fructose by specific elution from phosphocellulose with fructose 6-phosphate and had an apparent molecular weight of about 100,000, 6-phosphofructo 2-kinase activity copurified with fructose 2,6-bisphosphatase activity at each step of the purification scheme. Incubation of the purified protein with [gamma-32P]ATP and the catalytic subunit of the cAMP-dependent protein kinase resulted in the incorporation of 1 mol of 32P/mol of enzyme subunit (Mr = 50,000). Concomitant with this phosphorylation was an activation of the fructose 2,6-bisphosphatase and an inhibition of the 6-phosphofructo 2-kinase activity. Glucagon addition to isolated hepatocytes also resulted in an inhibition of 6-phosphofructo 2-kinase and activation of fructose 2,6-bisphosphatase measured in cell extracts, suggesting that the hormone regulates the level of fructose 2,6-bisphosphate by affecting both synthesis and degradation of the compound. These findings suggest that this enzyme has both phosphohydrolase and phosphotransferase activities i.e. that it is bifunctional, and that both activities can be regulated by cAMP-dependent phosphorylation.

Animals↗
PubMed1982

Area postrema lesions produce feeding deficits in the rat: effects of preoperative dieting and 2-deoxy-D-glucose.

To investigate the possible role of the area postrema (AP) in the control of food intake and body weight, male albino rats were divided into four groups: (a) animals dieted to 80% of their original body weights prior to receiving AP lesions, (b) nondieted animals with AP lesions, (c) animals dieted to 80% prior to receiving sham lesions, and (d) nondieted animals with sham lesions. Lesions of the AP in nondieted rats resulted in hypophagia, hypodipsia and body weight loss followed by recovery of normal intake and maintenance of body weight at a fixed percentage of the sham operated animals' weight. Reducing body weight prior to surgery led to body weight maintenance levels equivalent to those of the nondieted groups. We also tested the animals for sensitivity to glucoprivation caused by intraperitoneal injections of 2-deoxy-D-glucose (2-DG). Injections of 2-DG produced hyperphagia in sham lesioned rats, but not in rats with AP lesions. Our data suggest that the effects of AP lesions on intake and body weight are similar, in several important respects, to the lateral hypothalamic feeding syndrome and to the effects of subdiaphragmatic vagotomy. We discuss the results with respect to hierarchical levels of neural circuitry involved in controlling feeding behavior.

Animals↗
PubMed1982

Fiber pathways associated with cerebellar self-stimulation in the rat: a retrograde and anterograde tracing study.

Intracranial self-stimulation (ICSS) was obtained from an area of cerebellum just rostro-ventral to the fastigial nucleus. The acquisition of cerebellar ICSS was slow, although this depended in part on the type of operant task required. The afferent and efferent fiber connections of the region of cerebellum supporting ICSS were identified using silver-degeneration and horseradish peroxidase tracing techniques. Two major pathways, one ascending to the ventromedial thalamus and one descending to the paramedian reticular formation and the region of the solitary nucleus, are discussed as possible substrates of ICSS at sites in the cerebellum as well as from other pontine and medullary regions.

Animals↗
PubMed1982

Yersinia arthritis: a clinical, immunological, and family study of 2 cases.

We describe 2 patients who presented with yersinia arthritis within a period of 5 months in Leicester. Both were HLA B27 positive. Arthritis followed 2 to 3 weeks after pneumonia, abdominal pain, dysuria, and evidence of hepatic involvement in the first case, and dysuria and conjunctivitis in the second. Immunological studies showed the presence of IgM, IgG, and IgA antibodies at a significant level against Yersinia enterocolitica serotype O:3 in serum and synovial fluid, and immune complexes in the serum of the first case and synovial fluid of both. Arthropathy resolved after 16 weeks in the first case and 12 weeks in the second, the latter requiring systemic corticosteroids. Family studies revealed psoriatic spondylarthritis in the brother, and bilateral sacroiliitis in the mother of the second case. Both were HLA B27 positive. These are the fourth and fifth reported cases of yersinia arthritis in Britain. We believe the condition is probably underdiagnosed and that yersiniosis should be considered as a possibility in otherwise unexplained arthritis.

Adult↗
PubMed1979

Biochemical, pathogenicity and toxicity studies of type III strains of Yersinia pseudotuberculosis isolated from the cecal contents of pigs.

Recent investigations have shown that the pig is a symptomless intestinal carrier of Y. pseudotuberculosis, the great majority of the strains isolated belonging to type III. Although these type III strains have a world-wide distribution there is little evidence to suggest that they are transferred readily to other animals and man. For that reason we examined the biochemical, pathogenic, immunogenic and exotoxin-producing properties of 24 type III strains isolated from the cecal contents of apparently healthy pigs. For comparison, we also examined type III strains from other sources, type I strains from normal pigs and isolates belonging to the other serotypes of Y. pseudotuberculosis. Biochemical reactions of type III strains were in accordance with data in the literature except for maltose and melibiose. Type III porcine strains were uniformly avirulent and atoxic but possessed a considerable degree of immunogenicity. On the other hand, type III strains isolated from aborted lambs and calves, although atoxic, were virulent for the guinea pig, as were also type I strains from healthy pigs. The pathogenic mechanism of Y.pseudotuberculosis, which is not unlike that found in E. coli, is discussed.

Animals↗