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D B Wilson

Publications and source records attributed to D B Wilson.

At least 181 records · Page 10Linked to original sources
PubMed1990

Oligomerization of the bacteriophage lambda S protein in the inner membrane of Escherichia coli.

Western blot (immunoblot) analysis of cell extracts from induced bacteriophage lambda lysogens probed with S-protein-specific antibody (raised against an S--beta-galactosidase fusion protein) demonstrated that the bacteriophage lambda S protein begins to appear 10 min after phage induction and is localized to the inner membrane at all times during the lytic cycle. Between 100 and 1,000 molecules of S protein per cell were present at the time of phage-induced lysis. Western blots of chemically cross-linked membranes from induced lysogens showed a ladder of bands at 18, 24, 32, and 42 kilodaltons (the S-protein monomer ran at 8 kilodaltons) that reacted with anti-S-protein antibody. Thus, the S protein appears to reside in the inner membrane as a multimer, and the molecular weights of the cross-linked species are consistent with those of S-protein homopolymers. Sodium dodecyl sulfate-resistant dimers were also detected when S protein was purified by immunoprecipitation.

Amino Acid Sequence↗
PubMed1990

Cloning and sequencing of a Bacteroides ruminicola B(1)4 endoglucanase gene.

Bacteroides ruminicola B(1)4, a noncellulolytic rumen bacterium, produces an endoglucanase (carboxymethylcellulase [CMCase]) that is excreted into the culture supernatant. Cultures grown on glucose, fructose, maltose, mannose, and cellobiose had high specific activities of CMCase (greater than 3 mmol of reducing sugar per mg of protein per min), but its synthesis was repressed by sucrose. B. rumincola did not grow on either ball-milled or acid-swollen cellulose even though the CMCase could hydrolyze swollen cellulose. The CMCase gene was cloned into Escherichia coli, and its nucleotide sequence contained a single open reading frame coding for a protein of 40,481 daltons. The enzyme was overproduced in E. coli under the control of the tac promoter and purified to homogeneity. The N-terminal sequence, amino acid composition, and molecular weight of the purified enzyme were similar to the values predicted from the open reading frame of the DNA sequence. However, the CMCase present in B. ruminicola was found to have a monomer molecular weight of 88,000 by Western immunoblotting. This discrepancy appeared to have resulted from our having cloned only part of the CMCase gene into E. coli. The amino acid sequence of the CMCase showed homology to sequences of beta-glucanases from Ruminococcus albus and Clostridium thermocellum.

Amino Acid Sequence↗
PubMed1990

A nonerythroid GATA-binding protein is required for function of the human preproendothelin-1 promoter in endothelial cells.

Endothelin-1 (ET-1) is a 21-amino-acid peptide synthesized by endothelial cells that has potent vasoconstrictor activity. Human ET-1 is derived from a 212-amino-acid prepropeptide, termed preproendothelin-1 (PPET-1). To identify cis-acting sequences essential for PPET-1 gene transcription, bovine aortic endothelial (BAE) cells were transfected with plasmids containing 5'-flanking sequences of the human PPET-1 gene fused to the human growth hormone gene as a reporter. Deletional analysis of these fusion plasmids showed that the sequence spanning positions -141 to -127 of the human PPET-1 promoter is required for full transcription activity. Introduction of clustered point mutations into this region of the promoter reduced transcription activity. Gel shift analysis, methylation interference, protein-DNA cross-linking, and oligonucleotide competition studies revealed that BAE cell nuclear extract contains a 47-kilodalton DNA-binding protein recognizing the core motif TATC (GATA) located at positions -135 to -132 of the PPET-1 promoter. The size and specificity of this DNA-binding protein resemble GF-1, a previously described transcription factor of erythroid cells that binds to the same core motif. Gel shift analysis indicated that GF-1 and the DNA-binding protein interacting with the PPET-1 promoter have different tissue distributions; the former is restricted to a subset of hematopoietic cells, and the latter is found in various cell types, including BAE, NIH 3T3, and HeLa cells. By using an antiserum to the C-terminal region of GF-1, the two proteins were also found to be antigenically distinct. When a growth hormone fusion plasmid containing the proximal 141 nucleotides of the PPET-1 promoter was transfected into a variety of cell types, these was preferential expression in cells of endothelial origin. We conclude that a nuclear factor with binding specificity for a GATA motif similar to that of the transcriptional activator GF-1 is necessary for the efficient and cell-specific expression of the human PPET-1 gene.

Animals↗
PubMed1990

Fourth branchial pouch sinus: principles of diagnosis and management.

The fourth branchial pouch sinus is a congenital anomaly which most frequently manifests itself by recurrent episodes of neck abscess or acute suppurative thyroiditis. This lesion usually becomes symptomatic before the age of 10 years and is more common than has previously been suspected. It has been found on the left side in 93% of the 28 cases reported in the English literature. Barium swallow during periods of quiescence and nasopharyngoscopy have frequently been successful in identifying the presence of these embryological remnants. Definitive therapy consists of total excision of the sinus tract, which can be facilitated by direct endoscopic placement of a Fogarty catheter into the sinus lumen before surgical exploration. The embryological basis for the occurrence of these sinuses is discussed.

Branchioma↗
PubMed1990

Daily intakes of nine nutritional elements: analyzed vs. calculated values.

The daily intakes for eight age-sex groups (infants, young children, and male and female teenagers, adults, and older adults) of nine nutritional elements (sodium, potassium, calcium, phosphorus, magnesium, iron, zinc, copper, and manganese) were obtained by laboratory analysis of the Food and Drug Administration's 234 Total Diet Study (TDS) foods and by use of the USDA Nutrient Data Base for Standard Reference. Food substitutions were required for eight TDS foods that had no direct counterparts in the USDA database. When corrections were made for missing values for magnesium, zinc, copper, and manganese in the USDA database, average percent differences between the two methods (USDA-TDS) for the age-sex groups were -2.6 for iron, 0.6 for manganese, 0.9 for zinc, 5 for potassium and phosphorus, 7 for magnesium, 8 for sodium and calcium, and 11.0 for copper. Data in the USDA database (when corrected for missing values) provided estimates of daily intakes of nine nutritional elements that were similar to those obtained by use of data from laboratory analysis in the TDS.

Adolescent↗
PubMed1990

Cranial effects of retinoic acid in the loop-tail (Lp) mutant mouse.

The effects of retinoic acid (RA) on the manifestation and nature of neural tube defects (NTD) in heterozygous embryos of mutant mice carrying the gene loop-tail (Lp) and in normal (+/+) littermates and embryos from normal homozygous matings were compared with NTD that occur in untreated abnormal homozygous (Lp/Lp) embryos. A single intraperitoneal dose (5 mg/kg) of RA administered at 9 AM or 3 PM on day 8 of gestation induced NTD in +/+ as well as Lp/+ embryos removed on day 12 of gestation. All of the NTD were confined to the brain and consisted of exencephaly involving the diencephalon, mesencephalon, and metencephalon. In neither phenotype (Lp/+; +/+) was the massive exencephaly and myeloschisis characteristic of untreated Lp/Lp embryos produced; thus, it is possible that the teratogenic mechanisms of RA-induced defects and of Lp-induced defects may differ.

Animals↗
PubMed1989

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Animals↗
PubMed1989

Axial interactions during neurogenesis in dysraphic mice.

The spatial relationships of midline axial structures were compared in normal and dysraphic embryos of the loop-tail (Lp) mutant mouse at 9 days of gestation, and the distribution of two glycoproteins, fibronectin and laminin, was determined in this region by means of immunofluorescence histochemistry. At various levels of the trunk in abnormal embryos, the notochord, ventral midline of the neural folds, dorsal aorta(e) and/or gut were variably separated from one another, in contrast to the closer contact that occurred among these midaxial structures at comparable trunk levels in normal embryos. Positive anti-fibronectin and anti-laminin reactions were noted within areas of contact in the normal embryos and at the interfaces of tissue separation in the abnormal embryos. Although the intensity of the immunofluorescent reaction could not be assessed or compared quantitatively, the presence and distribution of fibronectin and laminin in the abnormal embryos suggest that these two glycoproteins may not be causally or fundamentally involved in producing the abnormal spatial relationships and separation of the midaxial structures.

Animals↗
PubMed1989

Ultrastructural defects in the apical neural folds in mutant embryos with spina bifida.

Ultrastructural pathology in the apical neural folds was analyzed by means of tannic acid (TA) and ruthenium red (RR) cytochemistry in abnormal (vl/vl) mutant mouse embryos ranging in age from 17-35 somites. At lumbosacral levels of the spinal cord where closure fails to occur, as well as at more cranial levels where closure occurs but results in dorsal midline abnormalities, normal deposition of TA-positive and RR-positive material occurred in the space that develops between the overlying surface ectoderm (SE) and neuroepithelium (NE). However, in lumbosacral regions, pleomorphic excrescences projected abnormally from the apices of the transitional zone cells between SE and NE cells of the open neural folds. These abnormal projections consisted of enlarged cytoplasmic blebs, as well as entire cells. The cells were not necrotic nor did they show evidence of incipient degeneration. However, it is possible that they represent aberrant putative neural crest cells, as indicated by their location in the transitional zone and by the filopodia and lamellipodia projecting from their luminal surfaces.

Abnormalities, Multiple↗
PubMed1989

Immunofluorescent analysis of fibronectin and laminin distribution in the vl mutant mouse.

The distribution of fibronectin and laminin was determined in the basement membrane surrounding the caudal neural tube and at the site of initial apposition of the caudal neural folds by means of indirect immunofluorescence histochemistry on 9.0- to 10.5-day mouse embryos fixed in Carnoy's solution and serially sectioned in paraffin. At early phases of development of normal (+/+) and abnormal (vl/vl) embryos the dorsolateral neural basement membrane overlying putative neural crest cells caudal to the hindlimb shows a patchy fibronectin reaction, with laminin virtually absent. In older embryos, both components are present but are discontinuous overlying the neural crest. The results suggest that since discontinuities occur in the basement membrane of abnormal as well as normal embryos, the neutral crest cells are not prevented from emigrating from the abnormal neural tube; thus the faulty neural fold fusion that characterizes vl/vl embryos does not appear to be due to a suppression of emigration by the basement membrane. The results also demonstrate the advantages and reliability of embedding in paraffin for analysis of serially sectioned pathological material by means of indirect immunofluorescence, provided that normal controls and abnormals are processed simultaneously.

Animals↗
PubMed1989

Exercise-induced alterations of signal-averaged electrocardiograms in marathon runners.

Late potentials have been shown to predict malignant ventricular arrhythmias and sudden cardiac death. To determine whether prolonged, strenuous activity is associated with the development of ventricular late potentials, signal-averaged electrocardiography was performed on 30 marathon runners before, immediately after, and during a recovery period at least 1 week after they had a 26.2-mile race. The filtered QRS duration decreased immediately after the marathon to 94.4 +/- 10.0 msec from baseline values of 97.3 +/- 10.1 msec (p less than 0.005). Root mean square energy in the terminal 40 msec of the QRS complex increased immediately after the race from 60.4 +/- 35.6 uV to 71.0 +/- 41.7 uV (P less than 0.5). The duration of signals less than 40 uV in the terminal QRS were not appreciably altered. At the 1-week follow-up study, all parameters closely approximated the baseline values. No runner had a late potential after running the race. The one runner with a late potential at baseline had normal parameters immediately after the race. We conclude that signal-averaged ECG parameters are improved after a marathon is run, and the risk of an arrhythmic sudden death in adult runners without organic heart disease would seem to be low.

Adult↗
PubMed1989

Noninvasive assessment of myocardial dysfunction in patients with chronic aortic regurgitation.

Chronic aortic regurgitation may have minimal symptoms until severe myocardial dysfunction is apparent. Multiple preoperative indicators of postoperative prognosis have been sought. It appears that an elevated left ventricular end systolic dimension on echocardiography or elevated end systolic volume on radionuclide ventriculography in combination with depressed LV function and substantially increased calculated systolic wall stress may present an indicator for aortic valve replacement. Response of ejection fraction to stress may not be as reproducible, but when combined with a depressed resting ejection fraction may also be an indicator for aortic valve replacement. Even patients with severely depressed left ventricular ejection fraction may improve with surgery; however, the risks of a poor postoperative outcome is substantial increased. Appropriate management of a patient with chronic aortic regurgitation requires monitoring of multiple parameters during the patient's clinical course for optimal timing of valve replacement surgery.

Aortic Valve Insufficiency↗
PubMed1989

Cloning of a Thermomonospora fusca xylanase gene and its expression in Escherichia coli and Streptomyces lividans.

Thermomonospora fusca chromosomal DNA was partially digested with EcoRI to obtain 4- to 14-kilobase fragments, which were used to construct a library of recombinant phage by ligation with EcoRI arms of lambda gtWES. lambda B. A recombinant phage coding for xylanase activity which contained a 14-kilobase insert was identified. The xylanase gene was localized to a 2.1-kilobase SalI fragment of the EcoRI insert by subcloning onto pBR322 and derivatives of pBR322 that can also replicate in Streptomyces lividans. The xylanase activity produced by S. lividans transformants was 10- to 20-fold higher than that produced by Escherichia coli transformants but only one-fourth the level produced by induced T. fusca. A 30-kilodalton peptide with activity against both Remazol brilliant blue xylan and xylan was produced in S. lividans transformants that carried the 2.1-kilobase SalI fragment of T. fusca DNA and was not produced by control transformants. T. fusca cultures were found to contain a xylanase of a similar size that was induced by growth on xylan or Solka Floc. Antiserum directed against supernatant proteins isolated from a Solka Floc-grown T. fusca culture inhibited the xylanase activity of S. lividans transformants. The cloned T. fusca xylanase gene was expressed at about the same level in S. lividans grown in minimal medium containing either glucose, cellobiose, or xylan. The xylanase bound to and hydrolyzed insoluble xylan. The cloned xylanase appeared to be the same as the major protein in xylan-induced T. fusca culture supernatants, which also contained at least three additional minor proteins with xylanase activity and having apparent molecular masses of 43, 23, and 20 kilodaltons.

Bacteria↗
PubMed1989

Deposition of laminin and fibronectin in dysraphic mutant mice: an immunofluorescent study.

Abnormal loop-tail (Lp/Lp) mutant mouse embryos exhibiting severe exencephaly and myeloschisis were analyzed and compared with their normal (+/+; Lp/+) littermates by means of immunofluorescence histochemistry to determine regional differences in the distribution of laminin (L) and fibronectin (FN). In the neural basement membrane and adjacent mesenchymal cell matrix of the abnormal embryos, regional differences in the deposition of L and FN were similar to those in normal littermates. Moreover, most of the putative neural crest (NC) cells appeared to emigrate normally in terms of their site of detachment and migration pathways, despite the severe topographic distortions and loss of neuroepithelial integrity. However, some putative NC cells projected incorrectly from the 'luminal' surface of the neuroepithelium, suggesting that some of the NC may be abnormal or sequestered and prevented from appropriate detachment and emigration from the neural tube.

Animals↗
PubMed1989

Nutritional elements in U.S. diets: results from the Total Diet Study, 1982 to 1986.

Through the Food and Drug Administration's Total Diet Study, the levels of 11 nutritional elements (sodium, potassium, calcium, phosphorus, magnesium, iron, zinc, copper, manganese, selenium, and iodine) in the diets of eight age-sex groups were determined for the 4 years between 1982 and 1986. The 234 Total Diet Study foods, which are representative of the U.S. food supply, were purchased, prepared for consumption, and analyzed for the elements four times each year. The results were combined with national food consumption data to estimate intakes for 6- to 11-month-old infants, 2-year-old children, 14- to 16-year-old boys and girls, 25- to 30-year-old men and women, and 60- to 65-year-old men and women. Six elements (calcium, magnesium, iron, zinc, copper, and manganese) were low (less than 80% of the Recommended Dietary Allowance or below the low end of the Estimated Safe and Adequate Daily Dietary Intake range) for three or more of the age-sex groups. Six elements were of concern for teenage girls and adult women, five for older women, three for 2-year-old children, two for teenage boys and older men, and only one for infants and adult men. Sodium levels (which did not include discretionary salt) were elevated for 2-year-old children and teenage boys, and iodine was elevated for all age-sex groups. A significant trend was noted only for iodine, the intake of which decreased during the 4-year period.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Cloning of Thermomonospora fusca genes coding for beta 1-4 endoglucanases E1, E2 and E5.

Thermomonospora fusca chromosomal DNA was partially digested with EcoRI and fragments in the size range from 4 to 15 kb were isolated, ligated into lambda gtWES.lambda B arms, packaged, and the recombinant phages plated on Escherichia coli. The plaques were screened for carboxymethyl cellulase (CMCase) activity by a gel overlay procedure, and 25 plaques were positive among the 15,000 plaques that were screened. Positive phages were amplified and used to prepare infected E. coli extracts which were assayed for CMCase activity before and after treatment with antisera prepared against five purified T. fusca beta 1-4 endoglucanases (E1-E5). One phage produced an enzyme that was inhibited by E1 antiserum, nine of the phages produced enzymes that were inhibited by E2 antiserum, 14 produced enzymes that were inhibited by E5 antiserum and the enzyme produced by the other phages was not inhibited by any of the five antisera. The DNA insert present in the phage coding for E1 was cut into a number of different fragments which were subcloned into E. coli first using lambda gtWES.lambda B and then plasmid pBR322. The smallest active subclone, pTE12, contained a 3.1-kb insert. The insert present in one of the phages coding for E2 was also subcloned and the smallest active subclone pTE23 contained a 2-kb insert. E. coli HB101 containing plasmid pTE12 or pTE23 produced enzymes that were identical to E1 and E2, respectively, in all the properties tested.

Bacteria, Aerobic↗