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C Carpenter

Publications and source records attributed to C Carpenter.

53 records · Page 3Linked to original sources
PubMed1984

Changes in the anti-lipolytic action and binding to plasma membranes of N6-L-phenylisopropyladenosine in adipocytes from starved and hypothyroid rats.

The anti-lipolytic effect of the adenosine analogue N6-L-phenylisopropyladenosine was studied with rat adipocytes incubated with a high concentration of adenosine deaminase (0.5 unit/ml, approx. 2.5 micrograms/ml) and concentrations of noradrenaline that were equieffective in different physiological states. These studies were performed to compare the fed and starved (24h) states and to compare a hypothyroid state (induced by feeding propylthiouracil + a low-iodine diet) with the euthyroid state. Starvation increased sensitivity of the cells to the lipolytic action of noradrenaline, while decreasing sensitivity to the antilipolytic action of phenylisopropyladenosine. Hypothyroidism resulted in decreased sensitivity to noradrenaline and increased sensitivity to phenylisopropyladenosine. Studies of the binding of [3H]phenylisopropyladenosine to adipocyte plasma membranes indicated heterogeneity of binding sites or negative co-operativity in the binding. Starvation did not change [3H]phenylisopropyladenosine binding to membranes, whereas hypothyroidism caused an unexpected decrease in both the number and affinity of the binding sites. These observations are discussed in terms of the dual regulation of adipose-tissue lipolysis by lipolytic and anti-lipolytic agents.

Adenosine↗
PubMed1984

Skeletal myopathy and magnesium depletion: cellular mechanisms.

Muscle weakness and abnormal electrical activity of muscle cells have been described in magnesium-depleted patients and animals. The cellular mechanisms by which magnesium depletion causes the skeletal myopathy are not known. We review here the available clinical and experimental data on the effects of magnesium on: skeletal muscle cellular bioenergetics; excitation-contraction coupling, and biochemical and functional integrity of the cellular membrane. The data suggest that abnormalities in one or more of the above pathways may mediate the myopathy of magnesium depletion.

Adenosine Triphosphate↗
PubMed1983

Impaired energy metabolism in skeletal muscle during phosphate depletion.

The effects of phosphate depletion (PD) of 4, 8, and 12 weeks on skeletal muscle energy metabolism were studied in rats fed a phosphate deficiency diet and compared with rats pairfed with a normal phosphate diet. Skeletal muscle biopsy specimens were examined for energy production, transport, and utilization. The results show that already by 4 weeks of PD, the concentration of inorganic phosphorus of the skeletal muscle was significantly reduced and remained low thereafter. There was significant (P less than 0.01) and direct correlation between the cellular inorganic phosphorus and that of serum phosphorus. Adenine nucleotides, ATP, ADP, AMP, and creatine phosphate levels did not change. Mitochondrial respiration and oxidative phosphorylation were impaired by PD. Total cellular mitochondrial and myofibrillar creatine phosphokinase activities were significantly reduced at 4 weeks of PD and fell further at 8 and 12 weeks. There was a significant (P less than 0.01) and direct correlation between the activity of total extractable creatine phosphokinase and both serum and cellular levels of inorganic phosphorus. These data show that chronic PD is associated with a decrease in energy production, transfer, and utilization by skeletal muscle and provides information on the molecular events responsible for the myopathy of PD.

Animals↗
PubMed1982

Impaired energy metabolism in rat myocardium during phosphate depletion.

The effects of phosphate depletion (PD) of 4, 8, and 12 wk duration on myocardial energy metabolism were studied in rats fed a phosphate-deficient diet and compared with rats pair-fed a normal phosphate diet. Myocardial biopsies were examined for high-energy phosphate bonds. The results show that PD causes a significant reduction in myocardial concentration of inorganic phosphorus at 4 wk of PD and creatine phosphate at 8 wk of PD, while adenine nucleotides were significantly reduced only after 12 wk of PD. The changes in cellular inorganic phosphorus and creatine phosphate displayed a significant correlation with serum phosphorus levels. Mitochondrial respiration was impaired early in PD. Total cellular, mitochondrial, and myofibrillar creatine kinase activities were significantly reduced at 4 wk of PD and fell further at 8 and 12 wk. These data show that chronic PD is associated with reduced mitochondrial capacity to produce ATP, impaired transport via the creatine phosphate shuttle, and reduced myofibrillar ability to utilize ATP. These abnormalities indicate that all steps of myocardial energetics are impaired in PD and provide the molecular basis for the altered myocardial function seen in PD.

Animals↗
PubMed1981

HLA antigens and islet cell antibodies in gestational diabetes.

The HLA antigens of 136 patients with gestational diabetes are compared with control populations. No significant variations are observed in their frequencies, particularly for those antigens associated with Type 1 diabetes mellitus. Islet cell antibodies have also been studied in the serum of 52 of these patients and 20 of them were positive, whereas only one of 37 pregnant nondiabetic women had such antibodies (chi 2 = 15.2). A very high association between ICA and DR3 and DR4 was encountered (chi 2 = 17, with two df); half of the patients positive for either one of these antigens were ICA positive. These results indicate that ICA associates equally with DR3 and DR4, against the hypothesis that this expression of autoimmunity is more a characteristic of DR3- than of DR4-associated genetic susceptibility. These patients will be followed to determine if the ICA+ individuals are at increased risk for the development of insulin-dependent diabetes.

Adult↗
PubMed1968

Effect of p-fluorophenylalanine on chromosome replication in Escherichia coli.

The effect of p-fluorophenylalanine (FPA) on deoxyribonucleic acid (DNA) synthesis and chromosome replication was studied in a thymine-requiring mutant of Escherichia coli. The rate and extent of chromosome replication were followed by labeling the DNA with isotopic thymine and a density marker, bromouracil. The DNA was extracted and analyzed by CsCl gradient centrifugation. The block in chromosome replication caused by high concentrations of FPA occurred at the same point on the chromosome as that caused by amino acid starvation. In a random culture, DNA in cells treated with FPA replicated only slightly slower than the DNA from cells that were not exposed to the analogue. In cultures which had been previously starved for thymine, however, the DNA from the cells treated with FPA showed a marked decrease in the rate and extent of replication. It was concluded that the E. coli cell is most sensitive to FPA when a new cycle of chromosome replication is being initiated at the beginning of the chromosome.

Amino Acids↗
PubMedDate not supplied

Toxic shock syndrome as a complication of orthopaedic surgery.

Toxic shock syndrome (TSS) was initially described by Todd et al. in 1978. TSS as a complication of orthopaedic surgery was reported in 1984. There have been previously a total of nine cases of TSS reported in orthopaedic patients. These patients presented at an average of 13 days postoperatively compared to 2 days for general surgical patients. Patients with external fixators, however, presented an average of 25 days postoperatively. Menstrual TSS and nonmenstrual TSS present similarly; however, the fatality rate is reported as 10 and 50%, respectively. There was a 27% case fatality rate in orthopaedic patients. Because TSS is not a septicemia but a toxemia, the treatment depends on aggressive hemodynamic stabilization rather than antibiotic therapy. The classical presentation of TSS is not often seen in patients with TSS complicating orthopaedic surgery. Wounds rarely have any signs of infection. This presentation may be even more difficult to identify due to the occasionally long latency period between surgery and the development of TSS. It appears that external fixators may be left in place if there are no signs of infection. This requires further study.

Child, Preschool↗
PubMedDate not supplied

Dual infection with Ehrlichia chaffeensis and a spotted fever group rickettsia: a case report.

Well-documented cases of simultaneous human infection with more than one tick-borne pathogen are rare. To our knowledge only two dual infections have been reported: simultaneous human infection with the agent of human granulocytic ehrlichiosis and Borrelia burgdorferi and simultaneous human infection with B. burgdorferi and Babesia microti (1-2). Rocky Mountain spotted fever has long been known to be endemic in North Carolina; cases of human ehrlichial infection were recognized there soon after Ehrlichia chaffeensis was recognized as an important cause of tick-borne disease in the southeastern United States. Because both Rocky Mountain spotted fever and ehrlichiosis are prevalent in North Carolina, occasional cases of simultaneous human infection by rickettsial and ehrlichial agents would not be surprising; however, no such cases seem to have been reported.

Adult↗
PubMedDate not supplied

Chlorine disinfection of recreational water for Cryptosporidium parvum.

We examined the effects of chlorine on oocyst viability, under the conditions of controlled pH and elevated calcium concentrations required for most community swimming pools. We found that fecal material may alter the Ct values (chlorine concentration in mg/L, multiplied by time in minutes) needed to disinfect swimming pools or other recreational water for Cryptosporidium parvum.

Animals↗