Biomedical subjects
Publications and source records attributed to G Wilson.
A precision difference time-domain reflectometry (TDR) technique is described for the investigation of the dielectric properties of cell suspensions. The dielectric spectra obtained for erythrocytes using TDR are comparable with those reported in previous dielectric studies employing frequency-domain technique.
Explore the source record for details and available documents.
OBJECTIVE: The study examined two hypotheses: that being laid off increases the likelihood of violence and that being employed in an industry in which employment is unexpectedly low decreases the likelihood of violence. METHODS: Logistic regression analyses were used to examine data for more than 4,000 persons who participated in initial and follow-up interviews as part of the Epidemiologic Catchment Area survey. Data for persons who were working and not violent at the time of the initial interview but who were unemployed at reinterview were examined, as were data for persons who remained employed in industries with low employment levels. RESULTS: The risk of violent behavior of those who were laid off was nearly six times higher than that of their employed counterparts. Controlling for concurrent psychiatric disorder did not reveal a lower risk. The risk of violent behavior was reduced among those who remained employed in industries where layoffs were occurring. CONCLUSIONS: Economic contraction seems to affect violence in the community in two countervailing processes--one process increases violence and one reduces it. However, the net effect may well be that violence decreases in communities experiencing economic contraction.
PURPOSE: Treatment of lymphomas with combination chemotherapy with or without radiation therapy (XRT) can result in long-term or permanent azoospermia. PATIENTS AND METHODS: Semen analyses of lymphoma patients were performed before, during, and after treatment with cyclophosphamide, doxorubicin, vincristine, prednisone, and bleomycin (CHOP-Bleo) chemotherapy. Some of the patients also received other drugs or radiation therapy. RESULTS: Although no patients were azoospermic before treatment, all were rendered azoospermic during treatment. Following the completion of treatment, the fraction of patients whose sperm counts recovered increased gradually over 5 years and plateaued by 7 years, with two thirds of the men achieving normospermic levels. Scattered gonadal radiation dose and cumulative cyclophosphamide dose were found to be independently significant determinants of recovery: the fraction of patients whose sperm counts recovered to 10 x 10(6)/mL were 83%, 47%, and 20% for those who received less than 9.5 g/m2 of cyclophosphamide, greater than 9.5 g/m2 of cyclophosphamide, and pelvic XRT, respectively. The inclusion of additional drugs and interferon alfa did not significantly affect the long-term recovery of spermatogenesis. CONCLUSION: Pelvic XRT and cumulative cyclophosphamide dosages greater than 9.5 g/m2 are associated with a high risk of permanent sterility in lymphoma patients treated with the CHOP-Bleo regimen.
The hypothesis that job loss affects the incidence of clinically significant alcohol abuse is tested using panel data from the Epidemiologic Catchment Area project. Results suggest that the incidence of clinically significant alcohol abuse is greater among those who have been laid off than among those who have not. However, employed persons in communities in which total employment is unexpectedly low are at reduced risk of becoming alcohol abusers. The implications of the results for economic policy and for mental health services are discussed briefly.
PURPOSE: To determine under what conditions hydrogen peroxide (H2O2) can penetrate the cornea and cause increased concentrations of H2O2 in the aqueous humor. METHODS: Rabbit corneas were exposed in vitro and in vivo to H2O2 concentrations up to 60 mmol/l either in a 600 microliter volume or as consecutive drops. H2O2 was measured over time either in the endothelial superfusate or in tapped samples of aqueous humor, and in the fluid applied to the ocular surface. The stability of exogenous H2O2 added directly to aqueous humor was also determined. RESULTS: Exogenous H2O2 in aqueous humor decays with a half-life of 20 minutes, chiefly as a result of catalase activity. When applied to the entire ocular surface, 600 microliters of 60 mmol/l H2O2 caused no change in the concentration in aqueous humor, but when applied to the corneal surface alone, penetration occurred at 18 mmol/l and above. When applied as eight 40-microliters drops to the ocular surface the threshold for H2O2 penetration was above 36 mmol/l. CONCLUSIONS: H2O2 is rapidly eliminated on the ocular surface, chiefly by enzyme activity of the conjunctiva and cornea. Threshold for penetration of H2O2 into the aqueous humor depends on volume, concentration, duration, and ocular surface exposed. In a healthy eye, exogenously derived H2O2 is eliminated by enzyme activity of the aqueous humor and tissues surrounding the anterior chamber.
Hydrogen peroxide is an effective and commonly used contact lens disinfectant that is also used as a preservative in certain ocular medications. We describe the effects of hydrogen peroxide on the cornea and anterior chamber following its topical application via a contact lens or as drops. The conditions for interaction of hydrogen peroxide with corneal and palpebral tissues and its accumulation within the aqueous humor are detailed. Values are given for thresholds at which hydrogen peroxide in specified concentrations, volumes, locations, and durations of exposure can cause ocular pain, swelling of the corneal stroma, damage to the endothelium, and penetration of the compound to the anterior chamber. The cornea and the palpebral tissues, together with the tear film, form a highly effective barrier and detoxifying system that, except under extreme, accidental circumstances, prevents both extra- and intraocular damage from use of hydrogen peroxide in contact lens care or in medications.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
BACKGROUND: Treatment of cancer with multiple-drug chemotherapy regimens or radiation therapy can cause either temporary azoospermia of various durations or permanent azoospermia in young men. METHODS: To identify which drugs in which doses contribute to long-term or permanent azoospermia, semen analyses were done on patients with Ewing and soft tissue sarcomas before, during, and after treatment with either CYADIC (cyclophosphamide, doxorubicin, and dacarbazine), or CYVADIC (vincristine added to CYADIC). Some patients also received other drugs or radiation therapy. RESULTS: From pretreatment levels that were similar to those of control subjects, sperm production declined to azoospermia within 4 months of treatment. Sperm production returned in some patients after treatment; 40% of men recovered to normospermic levels by 5 years after treatment. Few patients showed continued recovery of sperm production after that time. The cumulative dose of cyclophosphamide was the most significant determinant of recovery to normospermic levels; approximately 70% of those who had received doses less than 7.5 g/m2 (median, 4.1 g/m2) recovered, but only 10% recovered when doses exceeded 7.5 g/m2. CONCLUSIONS: Thus, a risk of permanent sterility is associated with the use of the CYADIC and CYVADIC regimens in young men, especially when the cumulative dose of cyclophosphamide is greater than 7.5 mg/m2.
Successful coronary thrombolysis depends on rapidly restoring blood flow and maintaining patency of the infarct-related artery. Although widely used as an adjunct to lytic therapy, heparin is limited in its ability to produce these effects. Since the limitations of heparin may reflect its inability to inactivate clot-bound thrombin, we developed a rat model of tissue plasminogen activator (t-PA) induced thrombolysis to compare doses of heparin, hirudin, hirulog (a synthetic hirudin-derived peptide), and D-Phe-Pro-ArgCH2Cl (PPACK) that produced a 4-fold prolongation of the baseline activated partial thromboplastin time (APTT) with saline in terms of their ability to accelerate thrombolysis and to prevent reocclusion. A thrombus rich in red cells and fibrin was formed in the distal aorta by applying an external constrictor after denuding the endothelium with a balloon catheter. Thrombolysis was induced with t-PA (1 mg/kg bolus, followed by 1 mg kg-1 h-1 over 30 min) and the rats were then randomized to receive a concomitant 80 min infusion of a thrombin inhibitor or saline. By continuously monitoring blood flow and pre- and post-stenotic blood pressures, the time to clot lysis, and the number of reocclusions were determined. Compared to saline, heparin had no significant effect on these variables.(ABSTRACT TRUNCATED AT 250 WORDS)
Explore the source record for details and available documents.
We use a streptavidin-based macromolecular complex (SBMC) labelled with the europium chelate of 4,7-bis (chlorosulfophenyl)-1,10-phenanthroline-2,9-dicarboxylic acid (BCPDA) as a staining reagent for biotinylated DNA present on nitrocellulose filters. The fluorescent spots or bands obtained can either be observed under UV illumination, photographed by instant camera photography or quantified by using a specially designed instrument working as a high resolution time-resolved fluorometric scanner. The detection limit is approximately 10 pg of target DNA. Various experiments with use of biotinylated DNA probes hybridized to Southern transferred targets have shown that the new procedure is a useful versatile non-isotopic methodology for staining DNA on solid supports.
To assess the natural history and potential risk factors in childhood dilated cardiomyopathy, we investigated 25 patients (ages 9.6 +/- 4.4 years) who presented after they were 2 years old. All patients had symptoms of congestive heart failure and reduced contractility with a dilated left ventricle at presentation. Two factors at presentation were significantly different between patients who died less than 1 year after the presentation (n = 14) and those who survived for more than 1 year (n = 9); cardiothoracic ratio (65.1% +/- 6.8% vs 57.1% +/- 6.1%, p less than 0.01) and left ventricular ejection fraction (31.3% +/- 7.0% vs 40.0% +/- 6.2%, p less than 0.05). Irrespective of intensive medical therapy, dilated cardiomyopathy in children had a poor prognosis; the actuarial survival rate was 41% at 1 year and 20% at 3 years. Other forms of therapy should be considered in the early stages of dilated cardiomyopathy in this high-risk group.
Monoclonal antibodies were raised against a bacterial fusion protein containing amino acids 364 to 623 of the major nonstructural protein, NS-1, of minute virus of mice (MVMp), an autonomous parvovirus. By immunoblot analyses, these antibodies all recognized an 83-kDa protein in MVM-infected mouse fibroblast cells. Indirect immunofluorescence studies showed that five of the six react against a nuclear protein in MVM-infected mouse cells resulting in discrete foci of fluorescence. These foci do not correspond with the nucleoli, the site of MVM DNA replication. The epitopes of the antibodies were mapped using carboxy-terminal deleted bacterial fusion proteins derived from the plasmid encoding the original antigen and showed that four distinct epitopes were recognized by the different antibodies. A 25-amino-acid peptide was used in competition ELISAs to confirm the location of the epitope recognized by two antibodies CE10 and AC6. Preliminary characterization of an NS-1/NS-2 fusion protein synthesized in insect cells using a baculovirus expression vector showed that this fusion protein is also localized within the nucleus; however, in contrast, the full-length NS-1 polypeptide is located within the cytoplasm.
All low birthweight babies ventilated for the respiratory distress syndrome during a period of fourteen months were randomised to receive endotracheal suction 12-hourly or 6-hourly. There were no significant differences in respiratory outcome between the groups. These observations suggest that it is safe to aspirate endotracheal tubes infrequently during the first few days in uncomplicated respiratory distress syndrome.
We have defined a novel ovarian cancer-associated membrane antigen, 14C1, using human monoclonal antibodies derived by EBV-transformation of in situ sensitised patients' B-cells. The pattern of recognition of this antigen by these antibodies suggests that at least three epitopes are discernable. These antibodies can be used to promote the in vitro killing of ovarian cancer cells by activated macrophages and cytokines, implying a role for this antigen in the immunotherapy of ovarian malignancies. Evidence is presented that the 14C1 antigen may have some transmembrane signalling function.
It has been suggested in previous studies that the difference in endurance performance between males and females is related to gender-specific differences in cardiac function. Other studies have not equated males and females for physical condition, and this may have contributed to the findings. The purpose of this study was to determine the extent to which the difference in VO2max in groups of similarly trained males and females was explained by gender differences in cardiac size, fat-free weight (FFW) and hemoglobin concentration [( Hb]). Measurements of VO2max, FFW, [Hb] and cardiac size (LVM) were made on 19 males and 20 females comparable in age and cardiorespiratory capacity. The difference between men and women in LVM accounted for 68.3% of the gender difference in VO2max, and the combination of LVM and FFW accounted for 98.7% of the gender-related difference in VO2max. It was concluded that the gender difference in LVM accounts for a majority of the difference in VO2max in males and females, with other aspects of body size accounting for nearly all the remaining difference. The gender difference in heart size primarily reflects the smaller overall dimensions of women.