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Biomedical subjects

B Wright

Publications and source records attributed to B Wright.

At least 19 recordsLinked to original sources
PubMed1992

Case-control study of factors associated with failure to detect breast cancer by mammography.

BACKGROUND: Although mammography is widely used to detect breast cancer, it is recognized that not all cancers can be seen on mammographic images. PURPOSE: Our purpose was to examine factors associated with failure to detect breast cancer by mammography. METHODS: A case-control study was carried out in which subjects in whom histologically verified breast cancer was not detected by mammography (false negatives) were contrasted with subjects in whom breast cancer had been detected by mammography (true positives). Mammograms from individuals with histologically confirmed breast cancer were classified independently by two radiologists who were unaware of the clinical or other characteristics of the subjects. Histologic slides of all tumors were reviewed by one pathologist. RESULTS: Three variables were found to be independently and significantly associated with failure to detect breast cancer by mammography. Breast cancer was less likely to be detected by mammography in the presence of extensive parenchymal densities (odds ratio [OR] = 9; 95% confidence interval [CI] = 1.8-44.3), a tumor of lobular histology (OR = 7; 95% CI = 2.2-22.1), and tumors of small size (OR = 0.10; 95% CI = 0.0-0.9). CONCLUSION: Our results indicate that biologic factors are associated with failure to detect some breast cancers by mammography and indicate directions for future research in breast imaging.

Adult↗
PubMed1992

Combination therapy with zidovudine and dideoxycytidine in patients with advanced human immunodeficiency virus infection. A phase I/II study.

OBJECTIVE: To evaluate the safety and immunologic and antiviral effects of combination therapy with zidovudine and dideoxycytidine (ddC) in patients with advanced human immunodeficiency virus type 1 (HIV) infection. DESIGN: A phase I/II open-label, dose-ranging study. SETTING: Two AIDS Clinical Trials Group units. PATIENTS: Patients (56) with advanced HIV disease. INTERVENTIONS: Patients were randomly assigned to one of three paired regimens of zidovudine and ddC. We evaluated six dosing regimens, each involving oral administration of the study drugs at 8-hour intervals. MEASUREMENTS: Pharmacokinetics, toxicity, CD4 counts, p24 antigenemia and clinical end points. MAIN RESULTS: The median follow-up period was 40.6 weeks (range, 0.3 to 70 weeks). Neither drug affected the pharmacokinetic profile of the other. Episodes of serious hematologic toxicity were infrequent, occurring in only 17.9% of patients, and did not differ among the regimens (P = 0.15). Severe sensory peripheral neuropathy occurred in two patients (one patient each in regimens 1 and 4). One patient receiving regimen 4 died. The mean maximal increase in CD4 counts exceeded 109 cells/mm3, and 69% of patients receiving combinations containing 300 or 600 mg of zidovudine daily had an increase in CD4 counts of 50 cells/mm3 or greater. Regimens containing 600 mg of zidovudine daily (regimens 2 and 5) were also more likely to result in persistent increases in CD4 counts above pretreatment values than were the two lowest dose regimens (P = 0.003). The decline in CD4 counts was more rapid, and the suppression of the p24 antigenemia was less rapid and less sustained in patients receiving the lowest zidovudine dose alone (regimen 6). The addition of ddC to regimen 6 (regimen 3) resulted in a slower decline in the CD4 counts (P = 0.06). CONCLUSIONS: Combination therapy with zidovudine and ddC at the doses tested was well tolerated and did not result in toxicity. A daily oral dose of 150 mg of zidovudine appeared to produce a suboptimal effect on p24 antigenemia and CD4 counts. Combination therapy with ddC and higher doses of zidovudine produced greater and more persistent effects in patients with advanced HIV infection compared with other study regimens and with the results of previous trials of zidovudine monotherapy.

Adult↗
PubMed1992

Amplification of serotonin-induced arterial contractions with thrombin.

The purpose of this study was to determine if exposure of arteries to thrombin increases arterial sensitivity to serotonin and could thereby promote vasospasm. Rings of rabbit abdominal aorta, with endothelium intact or removed, were pretreated with vehicle or thrombin (2.5 U/mL). Thereafter, arterial contractions in response to cumulative additions of serotonin were recorded. Arterial contractions were expressed as a percentage of maximal potassium chloride-induced contractions. Arterial sensitivity was expressed as the EC50, the concentration of serotonin that produced a half-maximal contraction. Exposure of aortic rings to thrombin alone produced contractions of 11% and 22% for rings with and without endothelium, respectively. Removal of the endothelium had no effect on maximal serotonin-induced contractions (93% with endothelium vs 98% without). In contrast, maximal serotonin-induced contractile force was increased after pretreatment with thrombin (107% vs 121% for rings with and without endothelium, respectively; P less than .01). Arterial sensitivity to serotonin was not affected by the removal of endothelium. However, thrombin pretreatment increased (P less than .01) arterial sensitivity to serotonin 2.6-fold and 4.7-fold for rings with and without endothelium, respectively. The results of this study demonstrate that arterial contractions due to serotonin are amplified by thrombin and suggest that vasospasm may be more likely to occur at sites in arteries where the endothelium is absent and both thrombin and serotonin are present.

Animals↗
PubMed1992

Relationship between hypoxaemic and cardiac ischaemic events in the perioperative period.

We have used continuous and concurrent monitoring of arterial oxygen saturation (SpO2) and ECG to study the relationship between hypoxaemia and silent myocardial ischaemia in the perioperative period in 11 patients with cardiovascular disease. Ischaemic and hypoxaemic events occurred in all patients. Many events were shortlived and occurred independently of each other. However, our results suggest a close correlation between the duration of hypoxaemia and myocardial ischaemia. Ischaemia is more likely to occur if an episode of hypoxaemia is prolonged (beyond 5 min; P less than 0.01, chi square) and severe (SpO2 less than 85%; P less than 0.05, chi square).

Aged↗
PubMed1991

Peripheral nerve function in persons with asymptomatic or minimally symptomatic HIV disease: absence of zidovudine neurotoxicity.

Nucleoside-induced neuropathy characteristically appears as a painful, symmetric, distal polyneuropathy. To evaluate the neurotoxic potential of zidovudine (ZDV, or azidothymidine), in persons with little confounding human immunodeficiency virus (HIV) neuropathy, we evaluated peripheral nerve function in persons completing placebo-controlled studies of ZDV in early HIV disease. Participants had been receiving placebo or ZDV at doses of 800-1,200 mg daily for a median 52 weeks at the time of evaluation. Neuropathic symptoms and abnormalities of motor and sensory function were present in fewer than 10% of both treatment groups. Depressed reflexes were found in 19% of the ZDV group and 18% of the placebo group. Quantitative sensory testing for vibration was abnormal in fewer than 10% of participants and the absolute scores favored the ZDV group. We thus found a low prevalence of peripheral nerve abnormalities and no evidence of ZDV neurotoxicity in this population.

Acquired Immunodeficiency Syndrome↗
PubMed1990

A radiological presentation of neonatal and infantile syndromes.

The syndromes I have described are unfortunately not rare in Saudi and so the role of genetic counselling is an important, if difficult, one. Consanguinous marriages are a key cause of these diseases, but not one easily avoided. Marriage rituals in this part of the world are vastly different from those in the west. Many Saudis regard consanguinous unions, for example between cousins, as a further strengthening of family bonds. The role of genetics is not fully appreciated by parents and genetic disease is often attributed to other, extraneous causes: God's will; an illness suffered by the mother during pregnancy; or to the 'evil eye.' Even when genetic counsellors actively discourage parents who are at risk from having future children, this advice goes unheeded. Parents prefer to rely on: 'Insh'allah' or God's will' to safeguard them. Abortion is strictly prohibited by religious law and any affected offspring are cared for by a dedicated and loving family under the guidance of the Holy Qu'ran. They are rarely institutionalized.

Craniofacial Dysostosis↗
PubMed1988

Clinical trial of low-fat, high-carbohydrate diet in subjects with mammographic dysplasia: report of early outcomes.

Despite evidence that dietary fat intake may influence breast cancer risk, there is little information about the effects of dietary fat on the human breast. We have studied the effects of dietary fat on the breast by examining the influence of dietary fat reduction on mammographic dysplasia (nodular or sheetlike areas of radiological density). Subjects with mammographic dysplasia were randomly allocated to a control group, in which they received advice about maintaining a balanced diet (36% of calories as fat), or an intervention group, in which they were taught to reduce dietary fat to a target of 15% of calories. A total of 295 patients consented to randomization, and after 1 year, 20% of the intervention group and 5% of the control group had dropped out (failed to keep appointments and provide nutrient data). The remaining patients closely adhered to the dietary goals of the study as assessed by food records, chemical analysis of duplicate meals, and serum cholesterol measurements. Comparison of mammograms before and after 1 year of dietary fat reduction shows no significant influence on the extent or density of mammographic dysplasia. Surgical biopsies performed in subjects after entry in the study showed five cancers in the control group and two cancers in the intervention group; this total of seven cancers is four times the number expected. These data show that clinical trials of the effects of dietary fat reduction on breast cancer risk are feasible and that long-term compliance with a low-fat diet can be achieved, and they confirm that the patients selected because they had mammographic dysplasia had increased risk of breast cancer.

Adult↗
PubMed1988

Localized bone resorption in systemic sclerosis.

A case of progressive systemic sclerosis (PSS) is described in which painful bone resorption of both upper arms occurred. Computerized tomographic examination revealed cortical thinning with periosteal new bone formation, and pathologic examination revealed only a healing, fibrotic lesion. The cause of this rare occurrence in PSS remains unknown.

Adolescent↗
PubMed1987

A free radical scavenger role for daunomycin: inhibition of nonenzymatic oxidation of NADH.

The effect of daunomycin(Dm) on the nonenzymatic oxidation of NADH in the presence of metal ions, H2O2 and various ligands was examined. The results show that daunomycin inhibits the oxidation of NADH by reacting with one or more of the reaction intermediates which include OH., HO2., O2. and NAD.. This reaction is a reductive one involving the anthraquinone moiety of daunomycin as confirmed by control experiments by comparative UV-Vis analysis of the spectral character of daunomycin after reduction by NaBH4. Daunomycin, once reduced, apparently does not transfer its electron to another species such as O2 and is thus thought to play the role of free radical scavenger.

DNA↗
PubMed1986

Pyelonephritis associated with renal failure in a horse.

A 20-year-old gelding with weight loss and generalized weakness that progressed gradually over a 3-month period was diagnosed as having pyelonephritis caused by Staphylococcus aureus infection. Abnormal laboratory findings included high values for BUN, creatinine, potassium, and calcium, and depletion of sodium. Determination of glomerular filtration rate and effective renal plasma flow indicated a severe decrease in renal filtration and perfusion.

Animals↗
PubMed1986

A re-evaluation of the anxiolytic properties of intramuscular midazolam.

The observed effect of midazolam on anxiety is equivocal in part because previous studies have not ruled out pre-treatment differences in anxiety scores between patients who received midazolam and those who did not (controls). This study re-examines the anxiolytic effect of premedication with intramuscular midazolam using a sample size calculated to be of sufficient size to rule out population differences as a variable affecting treatment results. In the midazolam group (n = 49) anxiety scores were determined prior to administration of midazolam 0.07 mg/kg intramuscularly, and again 60 minutes later. In the control group (n = 47) anxiety scores were determined prior to intramuscular injection of a similar volume of matching placebo (midazolam vehicle), and again 60 minutes later. No differences in anxiety scores between groups either before treatments or 60 minutes after treatments were observed. Within both groups, anxiety scores at 60 minutes were no different from pre-treatment scores. In this study midazolam did not produce a statistically significant decrease in pre-operative anxiety scores at 60 minutes following intramuscular administration.

Adolescent↗