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Biomedical subjects

R Bazin

Publications and source records attributed to R Bazin.

At least 73 records · Page 4Linked to original sources
PubMed1987

Oligonucleotide probes for the detection of TEM-1 and TEM-2 beta-lactamase genes and their transposons.

We describe the use of molecular probes to detect the TEM-type beta-lactamase genes. As a general probe, we prepared a 656 base pair restriction fragment, entirely within the TEM structural gene. This probe was specific for the TEM family, hybridizing only with TEM-1 and TEM-2. The TEM-1 and TEM-2 beta-lactamases differ by only one amino acid. We synthesized two oligonucleotides whose central bases correspond to this difference. The use of these oligonucleotides enables us to discriminate between TEM-1 and TEM-2 genes. Using oligonucleotides homologous to parts of Tn3, we also monitored the presence of TnA-like transposons in bacteria harboring different beta-lactamase genes. Only the TEM-1 and TEM-2 genes were found to be on transposons with terminal sequences identical to those of Tn3. All hybridization experiments were performed with both dot-blot and colony-hybridization techniques, and the suitability of these two methods for epidemiological studies is compared.

DNA Transposable Elements↗
PubMed1987

Deprivation of corticosterone does not prevent onset of obesity in Zucker fa/fa pups.

Adrenalectomy has been shown to reduce the development of obesity in adult Zucker fatty rat. In this study, we examined whether adrenalectomy could prevent the emergence of obesity and correct any of the first abnormalities to develop in fa/fa pups. Four-day-old Zucker pups were adrenalectomized and fed by adrenalectomized wet nurses until 11 days of age. The frequency distribution curves of fat cell volume clustered in two groups as they do in control litters, providing evidence that two phenotypes were present. Oxygen consumption measured at 8 days of age was significantly lower in fa/fa than in Fa/fa. Adrenalectomy did not restore the decreased oxygen consumption of fa/fa. In control litters, the GDP binding to brown adipose tissue mitochondria was twofold lower, whereas fatty acid synthase activity of this tissue was significantly increased in fa/fa pups. In inguinal adipose tissue of fa/fa pups, fatty acid synthase, and lipoprotein lipase activities were twice as active as in the tissue of lean pups. In adrenalectomized fa/fa pups, none of these metabolic abnormalities was corrected. The results demonstrate that adrenalectomy early in life did not prevent the emergence of obesity in suckling fa/fa rats.

Adipose Tissue↗
PubMed1987

Metastatic Pseudomonas endophthalmitis following bronchoscopy.

Symptoms of uveitis developed in the left eye of a 61-year-old woman 2 weeks after bronchoscopy to investigate hemoptysis. The true diagnosis of metastatic endophthalmitis was unsuspected for 1 month. Both sputum and vitreous samples yielded Pseudomonas aeruginosa when cultured. Despite aggressive medical treatment, subtotal vitrectomy and intraocular injections of antibiotics, enucleation was eventually necessary. To our knowledge this is the first reported case of metastatic endophthalmitis following bronchoscopy. It is also the first report of the concentration of ceftazidime pentahydrate in the vitreous humour of an infected human eye.

Bronchoscopy↗
PubMed1986

Expression of uncoupling protein mRNA in thermogenic or weakly thermogenic brown adipose tissue. Evidence for a rapid beta-adrenoreceptor-mediated and transcriptionally regulated step during activation of thermogenesis.

A cloned cDNA sequence for the unique mitochondrial uncoupling protein of rat brown adipose tissue has been used to assay the corresponding mRNA in several situations. When thermogenesis in brown adipose tissue is stimulated (exposure of adult rats to the cold, birth) a rapid and prolonged increase in the level of uncoupling protein mRNA is observed. Such an increase can be mimicked by injection of animals with a new beta-adrenoreceptor agonist BRL 26830A. Conversely it is known that mice and rats with genetic or surgical obesity have a weakly thermogenic brown adipose tissue with a reduced norepinephrine turnover. A reduced level of uncoupling protein mRNA was measured in obese fa/fa rats 10 days or 10 weeks old and in obese rats with a lesion of the ventromedial hypothalamic area but not in obese ob/ob mice. Moreover, exposure of obese animals to cold or dosing with BRL 26830A strikingly increased the level of uncoupling protein mRNA. Measurement of the relative concentration of nascent Ucp transcripts in nuclei isolated from brown adipose tissue indicates that Ucp gene is acutely (within 15 min) regulated at the level of transcription and is controlled via activation of beta-adrenoreceptors of plasma membrane. Ucp gene transcription is decreased in obese fa/fa rats but can be fully and rapidly turned on after injection of BRL 26830A.

Adipose Tissue, Brown↗
PubMed1986

Protective effect of the membrane skeleton on the immunologic reactivity of the human red cell Rho(D) antigen.

It has recently been shown that the 30,000 m.w. Rho(D) protein is associated with the membrane skeleton of the human red cell. We have studied the effects of the membrane skeleton on the immunoreactivity of the Rho(D) antigen present in Rho(D)+ membranes. Solubilization of the membranes with the Triton X-100 detergent and centrifugation of the extracts showed that more than 90% of the immunoreactive Rho(D) antigen sedimented with the membrane skeleton structures. The skeleton-bound Rho(D) antigen could be solubilized by disruption of the skeleton in low ionic strength medium. The removal of the membrane skeleton structure before the solubilization of the membranes with detergent resulted in the inactivation of the majority of the Rho(D) antigen. The effect of the membrane skeleton on the stability of the Rho(D) antigen was additionally studied in detergent extracts prepared from native and skeleton-free membranes. The assay of the Rho(D) antigen activity in the extracts showed that the Rho(D) antigen was 100 times more sensitive to the detergent inactivation in skeleton-free membranes than in native membranes. These results indicate that the membrane skeleton is important for stabilizing the immunoreactive form of the Rho(D) protein on the red cell membrane.

Antigen-Antibody Reactions↗
PubMed1986

[Effect of adrenalectomy on the capacity of brown adipose tissue for thermogenesis and the development of obesity in the fa/fa Zucker rat].

This study was undertaken to examine whether adrenalectomy performed during the weaning period could correct some of the first metabolic abnormalities to develop in obese fa/fa rats: impaired thermogenesis in brown adipose tissue and hyperlipogenesis in interscapular brown and white (inguinal) adipose tissues. Pups were adrenalectomized or sham-operated at 23 days of age and studied at 30 days of age. Body weight, interscapular brown adipose tissue and inguinal white adipose tissue weight were decreased after adrenalectomy in Fa/fa and fa/fa pups. Adrenalectomy had no effect on the thermogenic capacity of brown adipose tissue (as assessed by GDP binding to mitochondria) which remained significantly lower in fa/fa than in Fa/fa rats. In both Fa/fa and fa/fa rats the lipogenic capacity of brown and white adipose tissues (as assessed by fatty acid synthetase activity) was dramatically reduced by adrenalectomy. However, in adrenalectomized rats, the fatty acid synthetase activity of brown and white adipose tissue remained 2 and 5-fold higher, respectively, in fa/fa than in Fa/fa rats. These results show that adrenalectomy at postweaning, did not affect specifically the rats bearing the fatty genotype but induced large alterations in both groups of rats. Adrenalectomized fa/fa animals remained obese as compared to the appropriate controls.

Adipose Tissue↗
PubMed1985

Thermogenic and lipogenic activities in brown adipose tissue of I-strain mice.

The thermogenic capacity of brown adipose tissue has been investigated in I-strain mice to determine whether this tissue could play a role in the lower efficiency of food utilization reported in this strain of mice. (1) As compared with C57BL mice (a control strain), interscapular-brown-adipose-tissue weight and lipid percentage were decreased by 40% and 13% respectively in I-strain mice. (2) Mitochondrial protein content and cytochrome c oxidase activity were similar in the two strains, but the number of mitochondrial GDP-binding sites and uncoupling-protein content were increased by 2-fold in I-strain mice. (3) Fatty acid synthetase and citrate-cleavage enzyme (units/mg of protein) were 3-fold higher in the brown adipose tissue of I-strain mice. These results indicate that I-strain mice possess a very active brown adipose tissue. This enhanced capacity of energy dissipation in brown adipose tissue could contribute to the decreased capacity of I-strain mice to store adipose tissue.

ATP Citrate (pro-S)-Lyase↗
PubMed1985

Increased capacity for fatty acid synthesis in white and brown adipose tissues from 7-day-old obese Zucker pups.

The activity of fatty acid synthetase was measured in liver, and white and brown adipose tissues of suckling lean and obese Zucker pups. In contrast to liver where no change could be observed, a significant increase in fatty acid synthetase activity was detected in both white and brown adipose tissues as early as 7 days of age. When the enzyme activity was expressed per inguinal fat pad whose weight was increased by 30 per cent in obese as compared to lean pups, a 50 per cent increase in fatty acid synthetase activity was observed. The increased activity was mediated through an increased enzyme content. Insulin levels were still identical in the two groups at 16 days of age but were significantly increased at days 17 and 18 in obese as compared to lean pups. The aetiological role of the increase in fatty acid synthetase, which is expressed in vivo, is discussed.

Adipose Tissue↗
PubMed1985

[Role of brown adipose tissue in the development of genetic obesity in the obese Zucker rat (fa/fa)].

The lipogenic capacity and thermogenic activity (assessed by GDP binding to mitochondrial) of brown adipose tissue was studied in lean (Fa/fa) and obese (fa/fa) suckling Zucker rat pups 2 and 10 days old. By 10 days of age, fat deposition, lipogenesis in vivo and fatty acid synthetase activity were 1.5 to 2-fold higher, whereas GDP binding to mitochondria was 40% lower in pre obese than in lean pups. Compared with lean pups, 2-day old fa/fa pups showed a 60% increase in triglyceride accumulation in interscapular brown adipose tissue and a 30% decrease in GDP binding to mitochondria, while no change occurred in fatty acid synthetase activity. These results strongly suggest that an impaired thermogenic activity in the brown adipose tissue of fa/fa pups could play a key role in the development of obesity. However, the concomitant increase in fat content in the brown adipose tissue of 2-day old pre-obese pups raises the question of the causal relationship between these two disorders.

Adipose Tissue, Brown↗
PubMed1984

Evidence for decreased GDP binding to brown-adipose-tissue mitochondria of obese Zucker (fa/fa) rats in the very first days of life.

GDP binding to brown-adipose-tissue mitochondria of obese Zucker-rat (fa/fa) pups aged 2-14 days was significantly less than in lean control rats. Scatchard analysis in 10-day-old pups suggests that there was a large decrease in GDP-binding sites. However, a significant increase in fat content in brown adipose tissue of 2-day-old pre-obese pups raised the question of the sequential order and causal relationship between these two derangements.

Adipose Tissue, Brown↗
PubMed1983

Development of fatty acid-synthetic capacity in interscapular brown adipose tissue during suckling in genetically obese Zucker rats.

The development of the lipogenic capacity in brown adipose tissue was studied in suckling lean (Fa/fa) and obese (fa/fa) Zucker pups aged from 7 to 22 days. In both lean and obese pups, activities of the two key lipogenic enzymes, fatty acid synthetase and acetyl-CoA carboxylase, and of citrate cleavage enzyme rose from the early to the late suckling period. Compared with lean pups, 7-day-old fa/fa pups showed a 35% increase in fat accumulation in interscapular brown adipose tissue and a 25% increase in fatty acid synthetase activity. By 10 days of age, fat deposition, lipogenesis in vivo (assessed by the incorporation of 3H from 3H2O into fatty acids) and fatty acid synthetase activity were 1.5-2-fold higher in pre-obese than in lean pups. Compared with lean pups, the increased lipogenesis in vivo observed in brown adipose tissue of 10-day-old pre-obese pups could not entirely account for the difference in fat deposition observed in this tissue, suggesting that additional mechanisms are at play to explain the increased fat content of this tissue.

Acetyl-CoA Carboxylase↗
PubMed1983

[Analysis of the rebound phenomenon during outflow in plethysmography following programmed venous occlusion].

The venous outflow curve obtained using strain gauge plethysmography (Periflow JSI) frequently displays a slope change which modifies the classic exponential pattern: The semi-continuous arterial blood flow measurement together with an ECG-triggered plethysmography let the authors show the arterial origin of this slope change they called "the rebound phenomenon". Venous occlusion induces an ischemia which creates a reactive hyperemia when the venous blood current is let free. All the venous outflow curves stem from both a venous and arterial phenomenon. This latter may sometimes be of importance and has to be considered in plethysmography studies.

Adult↗
PubMed1982

Evidence for a high fatty acid synthesis activity in interscapular brown adipose tissue of genetically obese Zucker rats.

Obese (fa/fa) rats (30 days old) exhibited a 50% increase in the weight of interscapular brown adipose tissue compared with their lean (Fa/fa) littermates. The tissue weight increase was accounted for by an increased fat content. Lipogenesis in vivo, as assessed by the incorporation of 3H from 3H2O into lipid, was increased 5-fold in brown adipose tissue of obese as compared with lean rats. Accordingly, acetyl-CoA carboxylase, fatty acid synthetase, citrate-cleavage enzyme and malic enzyme in this tissue were 4-8 times more active in obese than in lean rats.

Adipose Tissue, Brown↗
PubMed1982

Effects of high-fat diet on glucose metabolism in isolated pancreatic acini of rats.

The purpose of the present study was to document the metabolism of glucose and its responsiveness to insulin in isolated pancreatic acini from rats fed either a low- or high-fat diet. The different steps investigated were labeled glucose oxidation, lactate production, hexokinase activity, and glucose transport, which was assessed by using both 3-O-methylglucose and 2-deoxyglucose. The acinar capacity to metabolize glucose (sum of CO2 plus lactate) was decreased by 50% by feeding the rats a high-fat diet. The impairment of glucose metabolism could not be explained by a defect in the glucose phosphorylation step because hexokinase activity was not changed in isolated acini from rats fed a high-fat diet. The effect of a high-fat diet was entirely accounted for by a reduction in the glucose transport rate that was achieved through a decrease in glucose transport Vmax with no change in Km. We could not detect any effect of insulin on glucose metabolism or 2-deoxyglucose uptake, whatever the diet composition. This work establishes that a high-fat diet, known to markedly alter pancreatic exocrine enzymes, also induces a large decrease in acinar glycolytic flux, raising the question of the relation between these two sets of adaptive changes.

3-O-Methylglucose↗
PubMed1982

Development of hepatic and adipose tissue lipogenic enzymes and insulinemia during suckling and weaning on to a high-fat diet in Zucker rats.

This study was designed to monitor the developmental changes in insulinemia and lipogenic enzyme activities in both inguinal adipose tissue and liver during suckling (7, 9, 14, and 17 days of age) and weaning (22 and 30 days of age) on to either a low-fat or a high-fat diet in lean (Fa/fa) and obese (fa/fa) rats. Tissues were removed through surgery and genotypes were retrospectively determined. During suckling, there was no difference in liver enzyme activities between the two groups. In contrast, adipose tissue fatty acid synthetase was increased by 50% and citrate cleavage enzyme and malic enzyme by 30% by 9 days of age. By 17 days of age, there was a threefold elevation in these enzyme activities and 6-phosphogluconic dehydrogenase and a twofold increase in glucose-6-phosphate dehydrogenase per inguinal fat pad in fa/fa versus Fa/fa. Consistent with these results, fat pad weight was increased by 20%, 50%, and 100% at 9, 14, and 17 days of age, respectively, in obese as compared to lean pups. However only by 17 days of age could a slight but significant increase in insulin level be detected in obese pups. Enlargement of inguinal fat pad accelerated after weaning on to a low-fat diet and still more after weaning on to a high-fat diet. Weaning on to a low-fat diet elicited an induction of hepatic lipogenic enzymes two or three times greater in fa/fa than in lean pups, while weaning on to a high-fat diet blunted the differences between genotypes. The lipogenic enzyme activities displayed per total inguinal fat were three to ten times greater in obese than in lean pups, regardless of the diet. However, adipose tissue lipogenic enzyme activities were much lower after weaning on to a high-fat than on to a low-fat diet in obese pups. The high-fat diet was as effective as the low-fat diet in triggering hyperinsulinemia in obese pups. The increased adipose tissue capacity for lipogenesis, starting during the suckling period, could play an important etiologic role in the development and maintenance of obesity in the Zucker rat.-Bazin, R., and M. Lavau. Development of hepatic and adipose tissue lipogenic enzymes and insulinemia during suckling and weaning on to a high-fat diet in Zucker rats.

Adipose Tissue↗
PubMed1982

Inguinal fat pad weight plotted versus body weight as a method of genotype identification in 16-day-old Zucker rats.

By plotting the weights of inguinal fat pad versus body weights in littermates from fa/fa X Fa/fa crosses, we observed that the data distributed along two widely separated regression lines as of 16 days of age. This procedure enabled us to determine unequivocally the genotype of every pup in seven litters. By its rapidity, its simplicity, and reliability, this method of genotype identification may be useful to many investigators.

Adipose Tissue↗