Biomedical subjects

G L Wilson

Publications and source records attributed to G L Wilson.

At least 55 records · Page 3Linked to original sources

PubMed1993

Insulin resistance and mechanical dysfunction in hearts of Wistar rats with streptozotocin-induced non-insulin-dependent diabetes mellitus.

The present study correlates the insulin resistance seen in the myocardium of rats with streptozotocin-induced non-insulin-dependent diabetes mellitus with insulin secretory defects, hyperglycaemia and disease duration. Two-day-old male Wistar rats were given a bolus injection of streptozotocin (0.09 mg/g body weight) which caused glucose intolerance when these animals reached adulthood. Although these rats developed a progressive resistance to the actions of insulin in the heart this did not correlate with the development of glucose intolerance. However, a correlation was seen with a shift in insulin secretory response from hyper- to hypo-secretion which developed between 6 and 14 months of age. Moreover, this shift in secretory pattern can be associated with the onset of a cardiac mechanical malfunction.

Analysis of Variance↗

PubMed1993

Effects of chronic glipizide treatment on the NIDD heart.

Extrapancreatic activity of the sulfonylurea, glipizide, was evaluated in the neonatal streptozotocin-induced rat model of noninsulin-dependent diabetes. Two day old Wistar rats were given a bolus of streptozotocin (90 mg/kg i.p.) to cause noninsulin-dependent diabetes; these animals became severely glucose intolerant and eventually developed a cardiomyopathy characterized by reduced heart rate, contractility and cardiac output. Male littermates injected with citrate buffer served as nondiabetic controls. At four weeks of age, the nondiabetic and NIDD rats were administered by gavage either glipizide (2.5 mg/kg) or the methyl cellulose vehicle. Throughout the treatment protocol, no difference in the degree of glucose intolerance was observed between the glipizide-treated and vehicle-treated animals. Glipizide therapy also was ineffective in improving plasma insulin levels, which were significantly depressed in the diabetic group. Yet, animals treated with glipizide for one year exhibited improved myocardial contractile function relative to the vehicle-fed or ad lib fed diabetic animals. Heart rate was significantly elevated and there was a tendency for both the rate of relaxation and contractility to be elevated in sulfonylurea-treated group. Glipizide also reduced the degree of insulin resistance in the heart. Since these changes occur in the absence of changes in glucose tolerance or insulin levels, the heart appears to be very sensitive to the direct effects of the sulfonylureas.

Animals↗

PubMed1993

Repair of N-methylpurines in the mitochondrial DNA of xeroderma pigmentosum complementation group D cells.

Previous work from our laboratory has shown that mitochondria are able to repair N-methylpurines formed by methylnitrosourea (MNU). However, it is unclear as to whether repair mechanisms that remove this type of lesion in nuclear DNA also remove these adducts in mitochondria. To address this question, we studied repair of MNU-induced N-methylpurines in the mitochondrial DNA from xeroderma pigmentosum complementation group D (XP-D) cells using quantitative Southern blot analysis and 32P-end-labeling techniques. These cells have been reported to be defective in the repair of this type of lesion in their nuclear genome. WI 38 cells were used as normal controls for these studies. Both XP-D fibroblasts and WI 38 cells were exposed to 0.5 mM MNU for 1 h. Following an 8 h repair period, 61% of N-methylpurines were repaired in the mitochondrial genome of XP-D cells and 39% of these lesions were repaired in WI 38 cells. After 24 h, XP-D cells had repaired 77% of the N-methylpurines in their mitochondrial genome, while WI 38 cells had 44% repair of this type of damage. During this same 24 h time period, 81.5% of the N7-methylguanines had been removed from the total cellular DNA of the WI 38 cells compared to only 38.3% repair of this lesion in the XP-D cells. Thus, XP-D cells, though deficient in the repair of N-methylpurines in their nuclear genome, are proficient in the repair of this type of damage in their mitochondria, suggesting that the mechanisms to repair N-methylpurines in the nuclear and mitochondrial genomes of these cells are different.

Blotting, Southern↗

PubMed1993

Repair of O6-methylguanine in rat pancreatic beta-cells after exposure to N-methyl-N-nitrosourea.

Because of the possible involvement of O6-methyldeoxyguanosine as a cytotoxic and carcinogenic lesion in pancreatic beta-cells, studies were undertaken to assess the ability of rat beta-cells to repair this DNA lesion. Primary cultures of neonatal rat beta-cells were shown to contain very low levels of O6-methylguanine-DNA-methyltransferase activity, the predominant mechanism for repairing O6-methyldeoxyguanosine in mammalian cells. However, using a 32P-endlabeling assay to measure O6-methyldeoxyguanosine in cells after exposure to N-methyl-N-nitrosourea, it was determined that rat beta-cells repaired O6-methyldeoxyguanosine to a substantial extent over a 24-h period. To elucidate the mechanism of O6-methyldeoxyguanosine repair in the virtual absence of constitutive O6-methylguanine-DNA-methyltransferase expression, studies were performed to determine if O6-methylguanine-DNA-methyltransferase expression was enhanced in N-methyl-N-nitrosourea-treated beta-cells. No increase in O6-methylguanine-DNA-methyltransferase activity was detected 24 or 48 h after exposure. However, Northern blot analysis showed a two- to threefold elevation in O6-methylguanine-DNA-methyltransferase messenger RNA levels in beta-cells 12 and 24 h after N-methyl-N-nitrosourea treatment. This finding is the first demonstration of a change in O6-methylguanine-DNA-methyltransferase messenger RNA levels in a cell type with low constitutive activity.

Animals↗

PubMed1992

Marital therapy formats: an analysis of acceptability ratings with married spouses.

One hundred thirty-five married individuals evaluated the acceptability of alternative therapeutic formats commonly employed in marital therapy. Distressed and nondistressed spouses were randomly assigned to experimental conditions including two types of educational information (descriptive and group-oriented) presented across three treatment formats (i.e., individual, conjoint, and group). Primary dependent variables included the Treatment Evaluation Inventory and the Semantic Differential. Results revealed that conjoint format was most acceptable, followed by group and individual, respectively. However, distressed spouses rated the group and conjoint formats as equal in acceptability. Group-oriented information increased nondistressed subjects' ratings of group format. The implications of these results for clinicians and researchers offering marital therapy are discussed.

Adult↗

PubMed1992

Therapeutic formats in the resolution of relationship dysfunction: an acceptability investigation.

The current study examined the acceptability of four treatment-formats commonly used in marital therapy: conjoint, concurrent, group, and individual. A total of 356 subjects were randomly assigned to experimental conditions. These included three types of information (descriptive, research-oriented, and group-oriented) and two differing case histories presented across the treatment formats. Results revealed a clear and consistent pattern of preference for conjoint therapy, followed by concurrent, group, and individual formats, respectively. It was also found that providing efficacy information about alternative formats and varying case histories did not alter acceptability ratings.

Adolescent↗

PubMed1992

An empirical evaluation of behavioral and cognitive-behavioral group marital treatments with discordant couples.

Previous research has revealed that group behavioral therapy for distressed couples provides an effective and efficient form of marital treatment. However, research comparing alternative group approaches is lacking. The current investigation evaluated group behavioral and cognitive-behavioral marital treatments across a variety of relationship dimensions and measures of individual functioning. Dysfunctional couples were randomly assigned to experimental conditions and demonstrated statistically and clinically significant improvement as contrasted with the waiting list control group. These results are discussed in terms of the differences between treatment conditions, potential advances in the field of marital therapy, and recommendations for further inquiry.

Adult↗

PubMed1992

Repair of mitochondrial DNA after various types of DNA damage in Chinese hamster ovary cells.

Using methodology recently developed to assess gene-specific DNA repair, we have demonstrated that it is possible not only to study mitochondrial DNA repair, but also directly to compare mitochondrial and nuclear DNA repair in the same biological sample. Complex enzymatic mechanisms recognize and repair nuclear DNA damage, but it has long been thought that there was no DNA repair in mitochondria. Therefore, in an attempt to delineate more clearly which DNA repair mechanisms, if any, are functioning in mitochondria, we have investigated the repair of several specific DNA lesions in mitochondrial DNA. They include cyclobutane dimers, cisplatin intrastrand adducts, cisplatin interstrand crosslinks and alkali-labile sites. We find that pyrimidine dimers and complex alkylation damage are not repaired in mitochondrial DNA, and that there is minimal repair of cisplatin intrastrand crosslinks. In contrast, there is efficient repair of cisplatin interstrand crosslinks as evidenced by approximately 70% of the lesions being removed by 24 h. Additionally, there is efficient repair of N-methylpurines following exposure to methylnitrosourea with approximately 70% of the lesions being removed by 24 h. The results of these studies reveal that repair capacity of mitochondrial DNA damage depends upon the type of lesion produced by the damaging agent. We speculate that a process similar to the base excision mechanism for nuclear DNA exists for mitochondrial DNA but that there is no nucleotide excision repair mechanism to remove more bulky lesions in this organelle.

Animals↗

PubMed1992

Bedside postpyloric placement of weighted feeding tubes.

A pilot study to evaluate a technique for the bedside placement of small-bore, weighted feeding tubes past the pylorus in critically ill patients is described. The technique involves the use of a #8 or #10 French small-bore, tungsten-weighted feeding tube, specific patient positioning, and defined insertion techniques, including gastric distention with air. The tubes were placed at the bedside in the intensive care unit by the nutrition support team nurse. Successful postpyloric placement was achieved in 85 (83%) of 103 patients. Approximate time for successful insertion was 30 minutes. A follow-up study to define factors influencing success or failure of this technique is planned.

Critical Care↗

PubMed1991

Analysis of cis-acting elements present in the CD20/B1 antigen promoter.

A genomic clone spanning a large portion of the 5' untranscribed region of the CD20 gene was isolated. Deletion analysis of subcloned fragments identified several regulatory elements. A major positive cis-acting element was localized between base pairs -290/-186. A second positive regulatory element was localized between -454/-280 and negative regulatory elements were present in the region between bp -828/-454. The sequence -280/-186 conferred B cell-specific expression on a heterologous, TATA box containing c-fos promoter. Electrophoretic mobility shift assays with overlapping oligonucleotide probes spanning -280/-186 revealed that a 25-bp probe (-225/-201) bound a nuclear protein present in B cell lines expressing the CD20/B1 antigen but not in Jurkat (T cell), U937 (promonocytic), U251 (glioma), or HeLa cells. To confirm the functional significance of this sequence, a trimer of this region was subcloned into the c-fos promoter containing CAT plasmid. Expression was observed only in BJA-B and HS-Sultan cells but not in CD20/B1- cell lines. This sequence element is also important in phorbol ester-induced CD20 expression in the pre-B cell line BP-697. These results partially characterize several regulatory elements present in the CD20 promoter that are likely important in the B cell-specific expression of the CD20 gene.

Antigens, CD↗

PubMed1991

Functional levels of mitochondrial anion transport proteins in non-insulin-dependent diabetes mellitus.

The effect of non-insulin-dependent diabetes mellitus (i.e., NIDDM; type 2 diabetes) on the levels of functional mitochondrial anion transport proteins has been determined utilizing a chemically-induced neonatal model of NIDDM. We hypothesized that moderate insulin deficiency exacerbated by the insulin resistance, which is characteristic of NIDDM, would cause changes in mitochondrial anion transporter function that were similar to those we have previously shown to occur in insulin-dependent diabetes mellitus (i.e., IDDM; type 1 diabetes) (Arch. Biochem. Biophys. 280: 181-191, 1990). Our experimental approach consisted of the extraction of the pyruvate, dicarboxylate and citrate transport proteins from the mitochondrial inner membrane with Triton X-114 using rat liver mitoplasts (prepared from diabetic and control animals) as the starting material, followed by the functional reconstitution of each transporter in a proteoliposomal system. This strategy permitted the quantification of the functional levels of these three transporters in the absence of the complications that arise when such measurements are carried out with intact mitochondria (or mitoplasts). We found that experimental NIDDM did not cause significant changes in the extractable and reconstitutable specific (and total) transport activities of the pyruvate, dicarboxylate, and citrate transporters. These results are in marked contrast to our previous findings obtained using rats with IDDM and negated our hypothesis. The present results, in combination with our earlier findings, allow us to conclude that insulin plays an important role in the regulation of mitochondrial anion transporter function.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Repair of alkali-labile sites within the mitochondrial DNA of RINr 38 cells after exposure to the nitrosourea streptozotocin.

Studies were initiated to investigate whether mechanisms exist within mitochondria to repair damage incurred by mitochondrial DNA after exposure to alkylating toxins. A clonal isolate from a rat insulinoma cell line was utilized to measure the formation and repair of alkali-labile sites within the mitochondrial genome after exposure to the alkylating antibiotic streptozotocin. Alkali-labile sites were formed in mitochondrial DNA in a dose-dependent fashion. Eight hours after exposure to the toxin, 55% of the lesions were removed. The level of repair increased to 70% after 24 h. In comparison, only 46% of N7-methylguanines were removed across the entire cellular genome. These studies demonstrate that streptozotocin causes appreciable mitochondrial DNA damage in a dose-dependent manner and provide the first evidence that a repair mechanism for alkali-labile sites is present within the mitochondrion.

Alkylating Agents↗

PubMed1991

Heterogeneous repair of methylnitrosourea-induced alkali-labile sites in different DNA sequences.

The repair of DNA damage induced by methylnitrosourea (MNU) in restriction fragments containing the dihydrofolate reductase (DHFR) gene in Chinese hamster ovary cells was compared to that in equal size restriction fragments containing a nontranscribed flanking sequence 3' to the DHFR gene or the c-fos gene. Following exposure to 10(-3) M MNU, restriction fragments containing either the DHFR gene or the 3' flanking sequence had similar amounts of alkali labile sites, approximately 2 sites/restriction fragment. Fragments encompassing the c-fos gene had less than 2 breaks/fragment. Twenty-four h after exposure to MNU a consistent, but slight and not statistically significant, difference was seen with more adducts removed from the DHFR gene than the 3' flanking sequence. No repair was detected in the c-fos containing fragments. In addition, the repair of N7-methylguanine in the overall genome was assessed by use of a 32P end-labeling technique. Seventy % of this major alkylation product was repaired after 24 h. These findings establish that repair heterogeneity occurs in Chinese hamster ovary cells after exposure to MNU.

Alkylation↗

PubMed1991

cDNA cloning of the B cell membrane protein CD22: a mediator of B-B cell interactions.

We have cloned a full-length cDNA for the B cell membrane protein CD22, which is referred to as B lymphocyte cell adhesion molecule (BL-CAM). Using subtractive hybridization techniques, several B lymphocyte-specific cDNAs were isolated. Northern blot analysis with one of the clones, clone 66, revealed expression in normal activated B cells and a variety of B cell lines, but not in normal activated T cells, T cell lines, Hela cells, or several tissues, including brain and placenta. One major transcript of approximately 3.3 kb was found in B cells although several smaller transcripts were also present in low amounts (approximately 2.6, 2.3, and 1.6 kb). Sequence analysis of a full-length cDNA clone revealed an open reading frame of 2,541 bases coding for a predicted protein of 847 amino acids with a molecular mass of 95 kD. The BL-CAM cDNA is nearly identical to a recently isolated cDNA clone for CD22, with the exception of an additional 531 bases in the coding region of BL-CAM. BL-CAM has a predicted transmembrane spanning region and a 140-amino acid intracytoplasmic domain. Search of the National Biological Research Foundation protein database revealed that this protein is a member of the immunoglobulin super family and that it had significant homology with three homotypic cell adhesion proteins: carcinoembryonic antigen (29% identity over 460 amino acids), myelin-associated glycoprotein (27% identity over 425 amino acids), and neural cell adhesion molecule (21.5% over 274 amino acids). Northern blot analysis revealed low-level BL-CAM mRNA expression in unactivated tonsillar B cells, which was rapidly increased after B cell activation with Staphylococcus aureus Cowan strain 1 and phorbol myristate acetate, but not by various cytokines, including interleukin 4 (IL-4), IL-6, and gamma interferon. In situ hybridization with an antisense BL-CAM RNA probe revealed expression in B cell-rich areas in tonsil and lymph node, although the most striking hybridization was in the germinal centers. COS cells transfected with a BL-CAM expression vector were immunofluorescently stained positively with two different CD22 antibodies, each of which recognizes a different epitope. Additionally, both normal tonsil B cells and a B cell line were found to adhere to COS transfected with BL-CAM in the sense but not the antisense direction.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMed1991

The effect of insulin supplementation on diabetes-induced alterations in the extractable levels of functional mitochondrial anion transport proteins.

The effect of insulin supplementation on diabetes-induced alterations in the levels of functional mitochondrial anion transport proteins has been determined. The experimental approach consisted of the extraction of the pyruvate, dicarboxylate, and citrate transport proteins from the mitochondrial inner membrane with Triton X-114 using rat liver mitoplasts (prepared from control, diabetic, or insulin-supplemented diabetic animals) as the starting material, followed by the reconstitution of the function of each transporter in a proteoliposomal system. This experimental strategy permitted the quantification of the functional levels of these three transporters in the absence of the complications that arise when such measurements are carried out with intact mitochondria (or mitoplasts). We found that treatment of diabetic rats (i.e., animals that were injected with streptozotocin 3 weeks earlier) on a daily basis with insulin for 3 weeks resulted in a reversal of the diabetes-induced (a) increase in the extractable and reconstitutable total (and specific) transport activities of the pyruvate and dicarboxylate transporters and (b) decrease in the activity of the citrate transporter. These findings indicate that diabetes-induced alterations in the functional levels of mitochondrial anion transport proteins are a direct consequence of the insulin insufficiency that characterizes this disease. Furthermore, this study provides the first demonstration that insulin participates in the regulation of the functional levels of liver mitochondrial anion transport proteins.

Animals↗

PubMed1991

Tissue disposition and excretion of 14C-labelled aflatoxin B1 after oral administration in channel catfish.

The pharmacokinetics, tissue distribution and excretion of 14C-labelled aflatoxin B1 (AFB1) were examined after oral administration (250 micrograms/kg body weight) in channel catfish (Ictalurus punctatus). Plasma concentrations of parent AFB1 were best described by a one-compartment pharmacokinetic model, in which peak plasma concentration (503 ppb) occurred at 4.1 hr after dosing. The absorption and elimination half-lives were 1.5 and 3.7 hr, respectively. AFB1 was highly bound (95%) to plasma proteins. Concentrations of 14C (in AFB1 equivalents) measured in the tissues were highest at 4 hr, ranging from 596 ppb in the plasma to 40 ppb in the muscle. AFB1 residues were rapidly depleted; at 24 hr the concentrations in the plasma and muscle were 32 and less than 5 ppb, respectively. Concentrations in the bile exceeded 2000 ppb (at 24 hr), whereas the highest concentration in the urine was 51 ppb (4-6-hr collection interval). Renal and biliary excretion accounted for less than 5% of the administered dose, indicating incomplete absorption. Pharmacokinetic modelling and tissue data demonstrate a very low potential for the accumulation of AFB1 and its metabolites in the edible flesh of channel catfish through the consumption of AFB1-contaminated feed.

Administration, Oral↗

PubMed1991

Estimation of the absorbed dose in radiation-processed food--1. Test of the EPR response function by a linear regression analysis.

Free radicals produced in chicken bone tissue by 137Cs gamma-rays were measured using electron paramagnetic resonance spectroscopy. The yield of radicals was found to be proportional to the absorbed dose. Additive re-irradiation of previously irradiated bones is the basis of a method to estimate the absorbed dose in radiation-processed foods. The ability of the method to provide accurate dose assessments for a range of doses (0.5-7.4 kGy) is tested here. A linear fit to the data yields reasonable dose estimates for bone irradiated less than 2 kGy, but fails at the higher doses using a linear approximation to the dose response. These data and their implications are discussed.

Animals↗

PubMed1991

Treatment acceptability of alternative sex therapies: a comparative analysis.

Eighty female subjects rated therapy descriptions of a case involving the treatment of inhibited female orgasm in group and individual formats. Half of the treatment descriptions described the patient's husband participating in some of the homework exercises. After each treatment description, subjects completed a series of treatment acceptability ratings (Treatment Evaluation Inventory, Semantic Differential, Credibility Rating Scale) designed to evaluate the alternative treatment dimensions. A case history of primary anorgasmia, representative of actual clients and problems typically seen in sex therapy clinics, was presented to subjects via written material and audiotape players. A clear preference for individual format over group format was consistently found in credibility and acceptability ratings. Inclusion of the identified patient's partner in therapy was not a salient factor in acceptability ratings for the female subjects. Implications of this research paradigm are discussed in light of the current state of the art in sex therapy, and future research needs are identified.

Adolescent↗