PubMed Health⌕ Search

Biomedical subjects

D Lockwood

Publications and source records attributed to D Lockwood.

At least 37 records · Page 2Linked to original sources
PubMed1989

Abnormal chromosome complement resulting from a familial inversion of chromosome 2.

It has been suggested that pericentric inversions of chromosome 2 increase the risk for spontaneous abortion but do not increase the risk for unbalanced recombinant offspring. We report our experience of a familial pericentric inversion of chromosome 2 resulting in two unbalanced recombinant offspring. Both subjects have 46,XX,rec(2),dup q,inv(2)(p25q35).

Abnormalities, Multiple↗
PubMed1989

Familial translocation t(9;16).

We report a female with a deletion of 9p and concomitant duplication of 16q [46,XX,-9,+der(9),t(9;16)(p24;q13)]. Parental chromosome analysis showed a balanced maternal translocation [46,XX,t(9;16)(p24;q13)]. Three other cases of translocations involving chromosomes 9 and 16 have been reported, one of them with identical breakpoints. A review of published reports of deletion 9p and duplication 16q is presented, and a comparison is made with previously described cases.

Abnormalities, Multiple↗
PubMed1988

New common fragile sites.

We report the finding of a large number of new common fragile sites. Thirty-one (56%) of 55 common fragile sites found in a sample of human lymphocytes were ones not described at the Eighth International Workshop on Human Gene Mapping (HGM 8). The sample consisted of 3023 lymphocytes from nine unrelated individuals with a history of genitourinary malignancy. The lymphocytes were challenged in culture with aphidicolin (Apc), fluorodeoxyuridine (FUdR), 5-azacytidine (Aza), and bromodeoxyuridine (BrdU). Thirteen of the new common fragile sites were induced by Apc and FUdR, nine by Aza, five by BrdU, and four by combined means. The sites induced by Apc and FUdR were cross-induced by BrdU. The fragile sites induced by a diminished concentration of Aza were largely located in heterochromatic regions and were cross-induced by BrdU and FUdR. Exposure to BrdU for 24 hours, a technique hitherto restricted to rare fragile sites, induced several common fragile sites. Control lymphocytes had far fewer gaps and breaks, but these were clustered predominantly at high-expression fragile sites. Because more than half of the common fragile sites in this study were new, it is clear that much remains to be learned. Because the classes of fragile sites reveal cross-induction, we propose that fragile sites share structures in DNA.

Aphidicolin↗
PubMed1988

Sensitisation by mycobacteria and the effects of BCG on children attending schools in the slums of Bombay.

Quadruple skin testing with new tuberculins was used to evaluate the effects of previously administered BCG Madras in children attending schools in the slums, or living in Kopri Leprosy Colony in Bombay. There were differences between schools both in the level of sensitisation of children without BCG scars and in the effects of BCG vaccination. Results obtained at one school resembled those obtained in a previous study in Agra, where BCG was thought to be ineffective. Results from the other schools and Kopri were more like those previously reported from Ahmednagar, where BCG was considered to be much more effective. Thus within the same city groups of children of the same social status may vary widely both in their contact with mycobacteria and in their capacity to benefit from BCG vaccination.

Adolescent↗
PubMed1988

Fragile sites and genitourinary tumors.

We tested for fragile sites in lymphocytes from nine patients with genitourinary tumors to determine if a correlation existed between their cancer chromosome breakpoints and fragile sites. Induction was done for rare fragile sites in all known classes by exposure of cells to fluorodeoxyuridine and bromodeoxyuridine (BrdU). No rare fragile sites were found. Induction was also done for common fragile sites in all known classes using aphidicolin (Apc), 5-azacytidine, and BrdU. Although 56 common fragile sites were detected, only a single site corresponded in location to a genitourinary tumor chromosome breakpoint. That was the common fragile site in band 3p14. No overall correlation was found between fragile sites and chromosome rearrangements in carcinoma of the kidney, ureter, bladder, and testis. The sole known candidate for a possible biologic role is the 3p14 common fragile site in renal cell carcinoma.

Bromodeoxyuridine↗
PubMed1988

Chromosome subband 17p11.2 deletion: a minute deletion syndrome.

Interstitial deletion of the short arm of chromosome 17 was detected in three unrelated patients with mental retardation and multiple congenital malformations. These patients were identified at a single centre over a six month period suggesting that del(17) (p11.2p11.2) is not a rare constitutional chromosome rearrangement. Comparison of the phenotypic features in a total of 19 patients with del(17)(p11.2p11.2) shows a consistent clinical phenotype with moderate to severe mental retardation, microbrachycelphaly, prominent forehead, broad face, flat midface, prognathism, short, broad hands, and behavioural anomalies such as self-mutilation. The sex ratio is unremarkable, parental ages are normal, and survival is usually unimpaired. Chromosome resolution of at least 500 bands appears necessary to detect this deletion.

Abnormalities, Multiple↗
PubMed1988

Effect of a sulfonylurea and insulin on energy expenditure in type II diabetes mellitus.

Previous studies demonstrated that administration of insulin and oral hypoglycemic agents tends to produce weight gain in type II diabetic patients. The goal of this study was to determine the potential contribution of changes in metabolic rate and urinary glucose excretion to changes in energy balance associated with treatment with glyburide and insulin. Six obese type II diabetic patients (52-61 yr old; 123-214% of ideal weight) were fed a weight-maintaining diet of fixed composition and caloric content in a Clinical Research Center. The mean fasting plasma glucose concentrations were 10.7 +/- 1.3 (+/- SE) mmol/L before treatment, 7.9 +/- 1.4 mmol/L at the end of 2 weeks of glyburide treatment, and 5.2 +/- 0.3 mmol/L at the end of 2 weeks of insulin treatment. Urinary glucose excretion decreased from 48 +/- 19 g/day before treatment to 20 +/- 9 g/day at the end of glyburide treatment and 2 +/- 1 g/day at the end of insulin treatment. Neither treatment affected mean postabsorptive resting metabolic rate (untreated 4.86 +/- 0.50 kJ/min; glyburide-treated, 4.63 +/- 0.45 kJ/min; insulin-treated, 4.70 +/- 0.46 kJ/min) or postprandial resting metabolic rate (untreated, 5.71 +/- 0.55 kJ/min; glyburide-treated, 5.60 +/- 0.39 kJ/min; insulin-treated, 5.70 +/- 0.51 kJ/min). However, the two patients with the largest decreases in urinary glucose excretion also had decreases in energy expenditure. These data indicate that many obese type II diabetic patients could have significant weight gain from reduced energy losses alone.

Blood Glucose↗
PubMed1988

Aspects of diabetes care in Britain, 1987.

The prevalence of diagnosed diabetes in Britain is rising rapidly. Hospital clinics are overcrowded and may only provide a rudimentary service. Various schemes have been devised to improve community care by involving hospital physicians and nurses. Trends towards increasing usage of human insulin, fixed ratio insulin mixtures and the Novopen, the declining popularity of CSII, and current attitudes towards diet are briefly summarised. Diabetic care in Britain has improved markedly over the past decade due particularly to improved patient education and the appointment of diabetes specialist nurses, but enormous logistical problems remain.

Community Health Services↗
PubMed1987

Expression and characterization of hepatitis B virus precore-core antigen in E. coli.

The hepatitis B virus core antigen, including the precore sequence (HBcAg-p25), was expressed at very high levels in bacteria. Three expression vectors were constructed in which the synthesis of HBcAg-p25 was controlled by the tac promoter, and the number of nucleotides between the bacterial ribosome binding site and the precore initiation codon was varied in order to maximize HBcAg-p25 synthesis. The relative amount of HBcAg-p25 polypeptide expressed by the different vectors was estimated by SDS-polyacrylamide gel electrophoresis and immunoblot. HBcAg-p25 was associated with an insoluble fraction of bacterial extracts and required ionic detergents for solubilization. Comparison by ELISA of the immunoreactivity of HBcAg with and without the precore sequence suggested that human anti-HBcAg IgG preferentially recognizes HBcAg lacking the precore sequence.

Chromobox Protein Homolog 5↗
PubMed1986

The effects of cyclosporin A on the early responses of B and T cells to Epstein-Barr virus infection.

The immunosuppressive properties of the fungal metabolite Cyclosporin A (CsA) on the human lymphocyte response to the polyclonal B cell activator Epstein-Barr virus (EBV) in vitro were assessed. CsA showed both stimulatory and inhibitory effects on EBV-induced IgM secretion, the net effect being dependent on the dose of virus used. T cells were required for both these effects to occur. A model is proposed to account for the complex interactions of CsA in this system.

Antibody Formation↗
PubMed1981

Adverse effects of liquid protein fast on the handling of magnesium, calcium and phosphorus.

We have studied the effect of a vitamin- and potassium-supplemented liquid protein fast on mineral metabolism of six obese subjects (five women, 1 man) for 40 days. Each patient was admitted to a metabolic ward and was given daily 300 Kcal, 75 mg of calcium, 406 mg of phosphorus, 7 mg of magnesium, 33 meq of potassium, and 11.5 g of nitrogen. Urinary calcium, phosphorus and magnesium levels were greatest during the first week, but decreased as the fast continued to 21, 31 and 300 percent, respectively, above intake. Cumulative urinary losses of calcium, phosphorus and magnesium were 58, 75 and 500 percent greater, respectively, than the cumulative intake. Fecal losses for calcium, phosphorus and magnesium were less than urinary losses throughout the study. Cumulative fecal losses of magnesium were more than 30 percent greater than dietary intake. Mean daily balances were -104 mg (calcium), -48 mg (magnesium) and -363 mg (phosphorus). Serum phosphorus and magnesium levels did not change. However, serum calcium levels decreased (-0.5 mg/dl, p less than 0.05). Serum bicarbonate levels decreased 20 percent during the first 8 days of the fast, at which time urinary ammonium was maximal, but later returned to control values despite sustained increases in serum and urinary acids throughout the fast. Ammonium excretion was 260 to 300 percent above control values. Urinary titratable acid excretion was greatest early in the fast but subsequently decreased as the excretion of phosphorus declined. Titratable acid accounted for less of the excreted acid (7 to 21 percent) than did ammonia (70 to 90 percent). It is concluded that a liquid protein fast results in negative mineral balance that is not reflected by serum values and is due primarily to renal losses. The losses of magnesium were proportionally greater than those of calcium and phosphorus. These studies indicate that a liquid protein fast results in depletion of the intracellular and/or skeletal stores of these minerals.

Adult↗
PubMed1981

Detection of extracellular toxin(s) produced by Vibrio vulnificus.

Conditions are described for the production, in high titers, a heat-labile, antigenic, extracellular toxin(s) by Vibrio vulnificus, a recently recognized human pathogen. Bacteriologically sterile culture filtrate preparations obtained from mid-logarithmic-phase cultures of the bacterium possessed cytolytic activity against mammalian erythrocytes, cytotoxic activity for Chinese hamster ovary cells, vascular permeability factor activity in guinea pig skin, and lethal activity for mice. The specific activity of toxin preparations from cultures of a virulent strain of the bacterium was ca. 25-fold more than that of toxin preparations obtained from cultures of a weakly virulent strain. The four toxic activities were inseparable by gel filtration with Sephadex G-100; however, two components, which had markedly different elution behavior but which possessed the four activities mentioned above, were obtained. The major (ca. 88% of the recovered activity) and minor components had apparent molecular weights of ca. 38,500 and greater than 150,000, respectively.

Animals↗