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David B Wilson

Publications and source records attributed to David B Wilson.

At least 19 recordsLinked to original sources
PubMed2007

GATA transcription factors in adrenal development and tumors.

Of the six GATA transcription factors, GATA-4 and GATA-6 are expressed in the mouse and human adrenal with distinct developmental profiles. GATA-4 is confined to the fetal cortex, i.e. to the less differentiated proliferating cells, while GATA-6 is expressed both in the fetal and adult adrenal. In vitro, GATA-4 regulates inhibin-alpha and steroidogenic factor-1 implicated in normal adrenal function. GATA-6 probably has roles in the development and differentiation of adrenocortical cells, and in the regulation of steroidogenesis. GATA-4 expression is dramatically upregulated and GATA-6 downregulated in gonadotropin dependent mouse adrenocortical tumors. This is accompanied by the appearance of luteinizing hormone receptor (LHR). In vitro, GATA-4 transactivates LHR promoter, and gonadotropins upregulate GATA-4 levels. Human adrenal tumors occasionally express GATA-4, whereas GATA-6 levels are usually lower than normal.

Adrenal Cortex Neoplasms↗
PubMed2007

Genome sequence and analysis of the soil cellulolytic actinomycete Thermobifida fusca YX.

Thermobifida fusca is a moderately thermophilic soil bacterium that belongs to Actinobacteria. It is a major degrader of plant cell walls and has been used as a model organism for the study of secreted, thermostable cellulases. The complete genome sequence showed that T. fusca has a single circular chromosome of 3,642,249 bp predicted to encode 3,117 proteins and 65 RNA species with a coding density of 85%. Genome analysis revealed the existence of 29 putative glycoside hydrolases in addition to the previously identified cellulases and xylanases. The glycosyl hydrolases include enzymes predicted to exhibit mainly dextran/starch- and xylan-degrading functions. T. fusca possesses two protein secretion systems: the sec general secretion system and the twin-arginine translocation system. Several of the secreted cellulases have sequence signatures indicating their secretion may be mediated by the twin-arginine translocation system. T. fusca has extensive transport systems for import of carbohydrates coupled to transcriptional regulators controlling the expression of the transporters and glycosylhydrolases. In addition to providing an overview of the physiology of a soil actinomycete, this study presents insights on the transcriptional regulation and secretion of cellulases which may facilitate the industrial exploitation of these systems.

Actinomycetales↗
PubMed2007

GATA-4 is required for sex steroidogenic cell development in the fetal mouse.

The transcription factor GATA-4 is expressed in Sertoli cells, steroidogenic Leydig cells, and other testicular somatic cells. Previous studies have established that interaction between GATA-4 and its cofactor FOG-2 is necessary for proper Sry expression and all subsequent steps in testicular organogenesis, including testis cord formation and differentiation of both Sertoli and fetal Leydig cells. Since fetal Leydig cell differentiation depends on Sertoli cell-derived factors, it has remained unclear whether GATA-4 has a cell autonomous role in Leydig cell development. We used two experimental systems to explore the role of GATA-4 in the ontogeny of testicular steroidogenic cells. First, chimeric mice were generated by injection of Gata4-/- ES cells into Rosa26 blastocysts. Analysis of the resultant chimeras showed that in developing testis Gata4-/- cells can contribute to fetal germ cells and interstitial fibroblasts but not fetal Leydig cells. Second, wild-type or Gata4-/- ES cells were injected into the flanks of intact or gonadectomized nude mice and the resultant teratomas examined for expression of steroidogenic markers. Wild-type but not Gata4-/- ES cells were capable of differentiating into gonadal-type steroidogenic lineages in teratomas grown in gonadectomized mice. In chimeric teratomas derived from mixtures of GFP-tagged Gata4+/+ ES cells and unlabeled Gata4-/- ES cells, sex steroidogenic cell differentiation was restricted to GFP-expressing cells. Collectively these data suggest that GATA-4 plays an integral role in the development of testicular steroidogenic cells.

Animals↗
PubMed2006

Characterization of a Thermobifida fusca beta-1,3-glucanase (Lam81A) with a potential role in plant biomass degradation.

Thermobifida fusca is a filamentous soil bacterium that plays a major role in the breakdown of plant biomass. In this paper, we report the cloning, expression, purification, and characterization of the T. fusca enzyme, Lam81A. The Carbohydrate Active Enzymes Database (http://afmb.cnrs-mrs.fr/CAZY/) indicates that Lam81A belongs to a relatively uncharacterized family of beta-1,3-glucanases, family GH-81 [Coutinho, P. M., and Henrissat, B. (1999) in Recent Advances in Carbohydrate Bioengineering (Gilbert, H. J., Davies, G., Henrissat, B., and Svensson, B., Eds.) pp 3-12, The Royal Society of Chemistry, Cambridge, U.K.]. Microarray analysis suggests that Lam81A plays a role in biomass degradation, where its natural substrate may be the plant cell wall polysaccharide, callose, which is a polymer of beta-1,3-linked glucose. Characterization of Lam81A has shown that the enzyme is specific for beta-1,3-linked glucose polysaccharides, is endohydrolytic, and utilizes an inverting mechanism for substrate hydrolysis. In addition, the enzyme has a broad pH optimum from 5.5 to 10, a temperature optimum of 50 degrees C, and demonstrates substrate inhibition, as well as showing a high basal level of expression.

Actinomycetales↗
PubMed2006

Clinical course of mesenteric artery stenosis in elderly americans.

BACKGROUND: To examine prospectively the relationship between stenosis or occlusion of the celiac and superior mesenteric arteries and symptoms of chronic intestinal ischemia in free-living elderly patients in the United States. METHODS: As part of an ancillary study to the Cardiovascular Health Study, participants in the Forsyth County (North Carolina) cohort underwent visceral duplex ultrasonography of the celiac and superior mesenteric arteries. Critical mesenteric artery stenosis (MAS) or occlusion was defined by Doppler flow ultrasound-derived criteria. Clinical outcomes were assessed at annual follow-up examinations and review of death certificates. Multivariate associations between the presence of MAS and all-cause mortality and adverse cardiovascular events were analyzed. Participants with MAS were contacted to determine the presence of symptoms consistent with chronic intestinal ischemia. RESULTS: Of 553 participants who underwent visceral duplex ultrasonography, 97 (17.5%) had disease of the celiac or superior mesenteric artery. At a mean follow-up of 6(1/2) years, 20 participants with MAS (20.6%) and 93 without MAS (20.4%) had died (relative risk, 1.01; 95% confidence interval, 0.66-1.55). No deaths were attributed to intestinal infarction. No association existed between the presence of MAS and prevalent cardiovascular disease, all-cause mortality, or adverse cardiovascular events. A questionnaire was completed by 71% of the surviving participants with MAS. No participant reported symptoms or weight loss consistent with chronic intestinal ischemia. CONCLUSIONS: Mesenteric artery stenosis was a common finding in free-living elderly patients. At long-term follow-up, the presence of asymptomatic MAS was not associated with death or adverse cardiovascular events. Participants with asymptomatic MAS by duplex ultrasonographic criteria did not experience intestinal infarction or develop chronic intestinal ischemia.

Aged↗
PubMed2006

Impaired mesenchymal cell function in Gata4 mutant mice leads to diaphragmatic hernias and primary lung defects.

Congenital diaphragmatic hernia (CDH) is an often fatal birth defect that is commonly associated with pulmonary hypoplasia and cardiac malformations. Some investigators hypothesize that this constellation of defects results from genetic or environmental triggers that disrupt mesenchymal cell function in not only the primordial diaphragm but also the thoracic organs. The alternative hypothesis is that the displacement of the abdominal viscera in the chest secondarily perturbs the development of the heart and lungs. Recently, loss-of-function mutations in the gene encoding FOG-2, a transcriptional co-regulator, have been linked to CDH and pulmonary hypoplasia in humans and mice. Here we show that mutagenesis of the gene for GATA-4, a transcription factor known to functionally interact with FOG-2, predisposes inbred mice to a similar set of birth defects. Analysis of wild-type mouse embryos demonstrated co-expression of Gata4 and Fog2 in mesenchymal cells of the developing diaphragm, lungs, and heart. A significant fraction of C57Bl/6 mice heterozygous for a Gata4 deletion mutation died within 1 day of birth. Developmental defects in the heterozygotes included midline diaphragmatic hernias, dilated distal airways, and cardiac malformations. Heterozygotes had any combination of these defects or none. In chimeric mice, Gata4(-/-) cells retained the capacity to contribute to cells in the diaphragmatic central tendon and lung mesenchyme, indicating that GATA-4 is not required for differentiation of these lineages. We conclude that GATA-4, like its co-regulator FOG-2, is required for proper mesenchymal cell function in the developing diaphragm, lungs, and heart.

Animals↗
PubMed2006

On blowing trumpets to the tulips: to prove or not to prove the null hypothesis--comment on Bösch, Steinkamp, and Boller (2006).

The H. Bösch, F. Steinkamp, and E. Boller meta-analysis reaches mixed and cautious conclusions about the possibility of psychokinesis. The authors argue that, for both methodological and philosophical reasons, it is nearly impossible to draw any conclusions from this body of research. The authors do not agree that any significant effect at all, no matter how small, is fundamentally important (Bösch et al., 2006, p. 517), and they suggest that psychokinesis researchers focus either on producing larger effects or on specifying the conditions under which they would be willing to accept the null hypothesis.

Humans↗
PubMed2006

Low frequency of telomerase RNA mutations among children with aplastic anemia or myelodysplastic syndrome.

Mutations in TERC, the RNA component of telomerase, result in autosomal dominant dyskeratosis congenita (DC), a rare bone marrow failure syndrome. TERC mutations have been detected in a subset of patients previously diagnosed with aplastic anemia and myelodysplastic syndrome (MDS), and these TERC mutations are clinically relevant as patients with DC respond poorly to conventional therapies. We aimed to determine the frequency of TERC mutations in pediatric patients with aplastic anemia and MDS who required a hematopoietic stem cell transplant. We obtained 284 blood samples from the National Donor Marrow Program Research Sample Repository from children and adolescents with bone marrow failure who underwent an unrelated stem cell transplant. We screened these samples for mutations in the TERC gene using direct DNA sequencing. We found 2 patients with sequence alterations in TERC. We identified a 2 base pair deletion (-240delCT) in a 4-year-old child with MDS and a single nucleotide alteration (-99-->CG) in a 1-year-old child with juvenile myelomonocytic leukemia. Screening for TERC gene mutations is unlikely to diagnose occult DC in children with severe bone marrow failure who require a hematopoietic stem cell transplant.

Adolescent↗
PubMed2005

Phenolic extraction from apple peel by cellulases from Thermobifida fusca.

With the optimization of the pretreatment conditions for the crude Thermobifida fusca cellulase activity and phenolic release from apple peel, we focused on the activity of individual purified cellulase related to the antioxidant activity. The overall phenolic release was significantly increased in a synergistic manner with combined pretreatment, not with individual pretreatment such as boiling, acid, and pectinase treatment. Approximately 60 mg of reducing sugar equivalent were produced per g of apple peel by treatment with T. fusca crude extract, and up to 3 times more reducing sugars were released when the apple peel was boiled and then treated with acid and pectinase. There was good correlation between the release of phenolics and reducing sugar by cellulase treatment and also between the amount of total phenolics and antioxidant capacity by each enzyme treatment (r2> 0.95). Among the tested enzymes purified from T. fusca cell extract, cellulase activity on apple peel was the highest with cellulase 6A (Cel 6A; 43% digestion), and the highest antioxidant capacity was obtained by incubation with Cel 6B (16 mg vitamin C equiv/g). Synergism in the activity was found from the combined treatment with Cel 6A and 6B in both cellulase activity and antioxidant capacity after 20 h of incubation. Cel 9A (progressive endocellulase) exhibited greater cellulase activity and antioxidant capacity than Cel 9A cd which lacks in cellulose-binding module, indicating that the cellulose-binding domain might play important roles in cellulolysis of apple peel. This study could provide some insights into the action mechanism of various cellulases on the digestion of cellulose-containing byproducts and expand the opportunity for cellulase utilization in the extraction of functional ingredients from the plant-derived byproducts.

Actinomycetales↗
PubMed2005

P-wave morphology correlation with left atrial volumes assessed by 2-dimensional echocardiography.

To correlate prespecified P-wave morphologies with echocardiographically derived left atrial volumes (LAVs), we studied a convenience sample of 71 patients with predominantly normal left ventricular systolic function (mean ejection fraction = 58.2% +/- 6.6%) who underwent concurrent 2-dimensional echocardiogram and 12-lead electrocardiogram. Left atrial volume was calculated from apical end-systolic images by the biplane method of disks and was indexed for body surface area (BSA). Electrocardiograms were assessed manually with calipers, measuring leading edge to leading edge. Patients included 34 men and 37 women with a mean age of 53 +/- 14 years. P-wave duration/PR-segment duration in lead II and depth and duration of terminal P wave in lead V1 (P terminal force) correlate poorly with LAV and provided only modest predictive power (area under receiver operating characteristic curve = 0.466-0.619 and r = 0.30-0.42, P = .014-.021). Total P-wave duration in lead II correlated moderately (r = 0.47, P < .001) and predicted LAV (LAV/BSA = 8.0 + 0.2 [P-wave duration in lead II]), as did P-wave area in lead II (r = 0.49, P < .001) (LAV/BSA = 18.6 + 1.7 [P-wave duration in lead II]). The 4 P-wave morphologies were found to be poorly sensitive but highly specific for left atrial enlargement.

Cardiomegaly↗
PubMed2005

Crystal structure of Thermobifida fusca endoglucanase Cel6A in complex with substrate and inhibitor: the role of tyrosine Y73 in substrate ring distortion.

Endoglucanase Cel6A from Thermobifida fusca hydrolyzes the beta-1,4 linkages in cellulose at accessible points along the polymer. The structure of the catalytic domain of Cel6A from T. fusca in complex with a nonhydrolysable substrate analogue that acts as an inhibitor, methylcellobiosyl-4-thio-beta-cellobioside (Glc(2)-S-Glc(2)), has been determined to 1.5 A resolution. The glycosyl unit in subsite -1 was sterically hindered by Tyr73 and forced into a distorted (2)S(o) conformation. In the enzyme where Tyr73 was mutated to a serine residue, the hindrance was removed and the glycosyl unit in subsite -1 had a relaxed (4)C(1) chair conformation. The relaxed conformation was seen in two complex structures of the mutated enzyme, with cellotetrose (Glc(4)) at 1.64 A and Glc(2)-S-Glc(2) at 1.04 A resolution.

Bacterial Proteins↗
PubMed2005

Gonadotropin-induced adrenocortical neoplasia in NU/J nude mice.

In response to prepubertal gonadectomy certain inbred mouse strains, including DBA/2J, develop sex steroid-producing adrenocortical neoplasms. This phenomenon has been attributed to a lack of gonadal hormones or a compensatory increase in gonadotropins. To assess the relative importance of these mechanisms, we created a new inbred model of adrenocortical neoplasia using female NU/J nude mice. These mice developed adrenocortical neoplasms in response to either gonadectomy or gonadotropin elevation from xenografts of human chorionic gonadotropin (hCG)-secreting Chinese hamster ovary cells. In each instance the adrenal tumors resembled the neoplasms found in gonadectomized DBA/2J mice and were composed of spindle-shaped A cells and lipid-laden B cells. Both cell populations were defined by ectopic expression of GATA-4 and an absence of the adrenocortical markers melanocortin-2-receptor and steroid 21-hydroxylase, but only B cells expressed the gonadal steroidogenic markers inhibin-alpha, LH receptor, P450c17, and P450c19. Expression of sex steroidogenic markers was attenuated in the neoplastic adrenal cortex of hCG-treated vs. gonadectomized mice. Whereas neoplastic adrenals were an obvious source of estradiol in gonadectomized mice, ovaries appeared to be the major source of this hormone in hCG-treated mice. Gonadectomy and hCG treatment elicited comparable increases in serum estradiol, but testosterone levels increased significantly only in hCG-treated mice. We conclude that chronic gonadotropin elevation, caused by either gonadectomy or hCG administration, signals a population of cells in the adrenal subcapsular region of permissive mice to undergo differentiation along a gonadal rather than an adrenal lineage. Thus, NU/J nude mice can be used as a model to study both neoplasia and adrenogonadal lineage specification.

Adrenal Cortex↗
PubMed2005

GATA-4:FOG interactions regulate gastric epithelial development in the mouse.

Transcription factor GATA-4 is a key participant in cytodifferentiation of the mouse hindstomach. Here we show that GATA-4 cooperates with a Friend-of-GATA (FOG) cofactor to direct gene expression in this segment of gut. Immunohistochemical staining revealed that GATA-4 and FOG-1 are co-expressed in hindstomach epithelial cells from embryonic days (E) 11.5 to 18.5. The other member of the mammalian FOG family, FOG-2, was not detected in gastric epithelium. To show that GATA-4:FOG interactions influence stomach development, we analyzed Gata4(ki/ki) mice, which express a mutant GATA-4 that cannot bind FOG cofactors. Sonic Hedgehog, an endoderm-derived signaling molecule normally down-regulated in the distal stomach, was over-expressed in hindstomach epithelium of E11.5 Gata4(ki/ki) mice, and there was a concomitant decrease in fibroblast growth factor-10 in adjacent mesenchyme. We conclude that functional interaction between GATA-4 and a member of the FOG family, presumably FOG-1, is required for proper epithelial-mesenchymal signaling in the developing stomach.

Animals↗
PubMed2005

Associations between retinal microvascular abnormalities and declining renal function in the elderly population: the Cardiovascular Health Study.

BACKGROUND: Microvascular abnormalities in the kidney are common histopathologic findings in individuals with chronic kidney disease or renal failure. These abnormalities may represent one manifestation of ongoing systemic microvascular damage. We hypothesized that retinal microvascular abnormalities, when present, would be associated with progressive renal dysfunction in elderly individuals. METHODS: The Cardiovascular Health Study (CHS) is a prospective, multicenter, cohort study initiated in 1989 designed to examine cardiovascular risk factors, morbidity, and mortality in elderly Americans. As part of an ancillary study, CHS participants underwent retinal photography in 1997 and 1998. Retinal microvascular abnormalities were assessed and graded by using standardized measures. Retinal microvascular abnormalities were defined as retinopathy (hard and soft exudates, hemorrhages, or microaneurysms) and/or retinal arteriolar abnormalities (arteriovenous nicking, focal arteriolar narrowing, or lowest quartile arteriole-venule ratio). Associations between these abnormalities and observed 4-year changes in serum creatinine levels and estimated glomerular filtration rates (eGFRs) from study years 5 to 9 (encompassing years 1994 to 2001) were examined by using regression modeling. RESULTS: A total of 1,394 CHS participants had retinal and serum creatinine data. After adjustments for age, race, sex, weight, diabetes, hypertension, angiotensin-converting enzyme inhibitor use, and proteinuria, participants with retinopathy showed a significant increase in serum creatinine level and decline in eGFR compared with those without retinopathy during the 4-year study period (+0.24 mg/dL [+21 micromol/L] versus -0.21 mg/dL [-19 micromol/L] and -0.48 mL/min/1.73 m2 [-0.01 mL/s/1.73 m2] versus +1.74 mL/min/1.73 m2 [+0.03 mL/s/1.73 m2], respectively). Participants with retinopathy also were significantly more likely to have an observed significant deterioration in renal function, defined as a 0.3-mg/dL (27-micromol/L) increase in serum creatinine level or 20% or greater decline in eGFR (odds ratio, 3.20; 95% confidence interval, 1.58 to 6.50; and odds ratio, 2.84; 95% confidence interval, 1.56 to 5.16, respectively). These associations remained in separate stratified analyses of patients with and without diabetes. The presence of retinal arteriolar abnormalities was not associated with deteriorating renal function. CONCLUSION: Retinal microvascular abnormalities defined as retinopathy were significantly associated with renal function deterioration. The observed findings were independent of effects of any associated diabetes or hypertension. These findings suggest that systemic microvascular disease may be associated with progressive renal dysfunction in the elderly population.

Black or African American↗
PubMed2005

Selective cadmium accumulation using recombinant Escherichia coli.

Recombinant Escherichia coli JM109 (pZH3-5/pMT), harboring a manganese transport gene (mntA) and a metal-sequestering protein (metallothionein [MT]) gene, was cultivated to accumulate cadmium (Cd) in an aqueous phase. Isopropyl beta-D-thiogalactoside (IPTG)-induced cells showed rapid Cd(2+) ion accumulation (90% of maximum accumulation in 15 min) and had an accumulation six times higher than that of the control. Under optimum conditions, i.e., pH 7, 37 degrees C and 0.5 (OD600), 1.5 mM IPTG induction resulted in the accumulation of 21.5 micromol Cd/g dry cell. Storage at 37 degrees C for 24 h had no effect on the accumulation. Significantly, Cd was selectively accumulated in a solution containing an equal concentration of three other metals, resulting in more than 90% of the total accumulated metals being Cd. The accumulation of Cd was reduced by the presence of Mn2+ ion whereas no significant effect was observed with Cu2+, Zn2+ and Pb2+ ions. A chelator, EDTA, had no effect on the accumulation up to 100 mM. The bioaccumulation rate followed Michaelis-Menten kinetics (Vm=2.7 micromol Cd2+/min.g dry cell, Km=0.67 microM). The equilibrium isotherm showed a Langmuir isotherm. In the membrane reactor experiment, 1 mg/l Cd in an inlet solution decreased to 0.2 mg/l in the effluent, removing 80% of Cd, continuously. These results indicated the potentials of a genetically modified microorganism for the highly selective accumulation of Cd at a low concentration and the future application to the removal and recovery of Cd.

Bacterial Proteins↗
PubMed2004

Transcription factor GATA-6 is expressed in the endocrine and GATA-4 in the exocrine pancreas.

GATA-4 and GATA-6 are zinc finger transcription factors that regulate gene expression, differentiation, and cell proliferation in various tissues. These factors have been implicated in the development of endodermal derivatives, including epithelial cells in the yolk sac, lung, and stomach. In the present study, we have characterized the expression of GATA-4 and GATA-6 during development of another endodermal derivative, the mouse pancreas, using a combination of in situ hybridization and immunohistochemistry. Neither GATA-4 nor GATA-6 antigen was detected in E10.5 pancreatic epithelial buds expressing Pdx-1. By E15.5, GATA-4 mRNA and protein were evident in developing pancreatic acini, but not in ductal or endocrine cells of the pancreas; GATA-6 mRNA and protein were present in both endocrine and exocrine cell precursors. In the newborn and adult pancreas, GATA-4 protein was seen in acinar cells, while GATA-6 antigen was found mainly in islet beta-cells. The amphicrine pancreatic AR42J-B13 cell line was used to study the expression of GATA-4 and GATA-6 during the differentiation of these cells towards an endocrine phenotype. Endocrine differentiation was associated with marked increase in GATA-6 but not GATA-4 mRNA levels. We conclude that GATA-4 is a marker of exocrine pancreatic differentiation, whereas GATA-6 is a marker of endocrine pancreatic development.

Animals↗
PubMed2004

Quantifying bacterial population dynamics in compost using 16S rRNA gene probes.

Composting provides a dynamic setting for studying ecological topics such as succession, competition, and community stability in a relatively short period of time. This study used hierarchical small sub-unit-based rRNA gene probes to quantify the change in the relative abundance of phylogenetic groups common to compost in laboratory scale reactors. Bacterial 16S rRNA gene targets accounted for only 37% of all small subunit (SSU) rRNA genes initially, but increased to a maximum of 83% of the total at 84 h. The sum of rRNA genes detected using probes specific to Pseudomonas and low-G+C Gram-positive rRNA genes represented between 16% and 87% of the total. The lack of hybridization to the taxon-specific probes was most pronounced between 36 h and 60 h, when the pH was between 4.6 and 4.8. During this period the relative abundance of taxon-specific gene targets accounted for only 17-33% of the total bacterial rRNA gene targets. Pseudomonas-type 16S rRNA genes were the most abundant of the groups measured until 72 h. Those genes had their highest relative abundance at 12 h (78% of bacterial rRNA genes; 30% of all rRNA genes), after which time their relative abundance began to decline as the temperature increased. Prior to 72 h, 16S rRNA genes from low-G+C Gram-positive bacteria (LGC-GPB) represented less than 7% of the bacterial rRNA genes. However, by 84 h the relative abundance of LGC-GPB and Bacillus rRNA genes had increased to 60% and 18% of the bacterial rRNA gene targets, respectively (50% and 15% of all rRNA genes, respectively).

Base Composition↗