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Biomedical subjects

W Jones

Publications and source records attributed to W Jones.

At least 163 records · Page 9Linked to original sources
PubMed1986

On the molecular mechanism of lactoperoxidase-catalyzed H2O2 metabolism and irreversible enzyme inactivation.

Lactoperoxidase-catalyzed H2O2 metabolism proceeds through one of three different pathways, depending on the nature and the concentration of the second substrate as an e- donor and/or on pH conditions. In the lactoperoxidase (LPO)-H2O2 system, at low H2O2 concentrations and/or alkaline conditions the peroxidatic cycle involves ferric LPO----compound I----compound II----ferric LPO conversion, whereas high H2O2 concentrations and/or acidic conditions favor the ferric LPO----compound I----compound II----compound III----ferrous LPO----ferric LPO pathway. The compound III/ferroperoxidase states are associated with irreversible enzyme inactivation by cleavage of the heme moiety and liberation of iron. It is likely that either singlet oxygen or superoxide and hydroxyl radicals are involved in the attack on heme iron, because inactivation correlates with oxygen production and can be decreased to a certain degree by scavengers such as ethanol, 1-propanol, 2-propanol, or mannitol. In the LPO-H2O2-I- system, the enzyme may also be inactivated by I2 generated in the course of enzymatic I- oxidation (i.e. during ferric LPO----compound I----ferric LPO cycles).

Ferric Compounds↗
PubMed1986

U.S. Senate voting on health and safety regulation: the effects of ideology and interest-group orientations.

Ideological and interest-group influences attempt to influence policy formulation during the legislative process. In health and safety policy-making these interest-group influences, which are some of the best organized groups, are related to ideological and interest-group orientations of the legislators themselves. The authors analyzed Senate health care voting in the 95th U.S. Congress. General ideology, structured along the left-right dimension was important, but it was not the overriding factor. The senators voted as supporters or opponents of environmentalism as much or even more than as adherents of either liberal or conservative beliefs.

Accident Prevention↗
PubMed1986

Collagen concentration as a significant variable for growth and morphology of mouse mammary parenchyma in collagen matrix culture.

Multicellular organoids of mouse mammary epithelium were established in culture either upon or within collagen matrices of various concentrations. Growth and tubule morphogenesis within the matrices were dependent upon the concentration of collagen, both being maximal in gels composed of 2 mg collagen/ml gel. Growth was more extensive in cultures established in gel than on gel especially at intermediate concentrations of collagen, with cell growth on gel seemingly independent of collagen concentration. Our results demonstrate that local collagen concentration can significantly affect epithelial cell growth and morphology.

Animals↗
PubMed1986

Do the American Medical Association's campaign contributions influence health care legislation?

Despite the fact that ideology and party overshadow campaign contributions as determinants of congressional voting behavior, the thesis of this study is that the American Medical Association's contributions have an important policy impact. Their donations had a significant effect on an index of three votes in 1979 in the House of Representatives. The contributions of the AMA had more of an effect than did those of the AFL-CIO. The AMA's money was related to decision-making in the Ways and Means and Energy and Commerce Committees. While the medical lobby does not dominate health care policy, its power should not be underestimated.

American Medical Association↗
PubMed1986

Disposition kinetics of cefamandole during continuous ambulatory peritoneal dialysis.

Cefamandole disposition kinetics were examined in six male subjects with renal impairment who were undergoing continuous ambulatory peritoneal dialysis. Creatinine clearance values ranged from less than 1 to 11 ml/min. Cefamandole was given as a 1-g intravenous dose infused over 30 min. Cefamandole concentrations were determined in serum, urine, and dialysis fluid by a high-performance liquid chromatographic method. The following average parameter values were obtained (range): half-life, 6.1 h (4.6 to 9.7); systemic clearance, 21.9 ml/min (8.4 to 35.5); renal clearance, 11.5 ml/min (0.03 to 22.3); dialysis clearance, 0.92 ml/min (0.7 to 1.3); nonrenal clearance, 12.2 ml/min (2.9 to 27.0); volume of distribution, 0.18 liter/kg (0.09 to 0.25); steady-state volume of distribution, 0.17 liter/kg (0.09 to 0.24). Approximately 5% of the dose was dialyzed (range, 2.8 to 8.3), indicating that there is no need to supplement a dosing regimen of cefamandole due to loss by dialysis. There was a positive correlation between creatinine clearance and the terminal elimination rate constant of cefamandole (r2 = 0.41) and cefamandole renal clearance (r2 = 0.83).

Cefamandole↗
PubMed1986

Evidence that calcitonin stimulates 1,25-dihydroxyvitamin D production and intestinal absorption of calcium in vivo.

Although it is well established that parathyroid hormone and phosphate are important regulators of 1,25-dihydroxyvitamin D [1,25(OH)2D] production, it remains unclear whether calcitonin affects vitamin D metabolism in vivo. Experiments were performed in the rat to determine the effect of chronic calcitonin infusion (0.2 U X h-1) on plasma levels of vitamin D metabolites and on calcium metabolism. Thyroparathyroidectomized animals fed a calcium-replete or calcium-free diet were studied for as long as 2 wk before they were killed. In control rats, a calcium-free diet alone for 12 d resulted in an increase in 1,25(OH)2D levels from 24 +/- 5 to 139 +/- 37 pg . ml-1, P = 0.025. The infusion of calcitonin also stimulated 1,25(OH)2D levels compared with controls on a regular diet (80 +/- 17 vs. 38 +/- 6 pg . ml-1, P less than 0.05) and on a calcium-free diet (460 +/- 50 vs. 139 +/- 37 pg . ml-1, P less than 0.001). In addition, calcitonin increased plasma calcium levels in animals on a regular diet by 50%; this effect was most likely due to increased intestinal absorption of calcium, because removal of calcium from the diet markedly blunted this effect. In contrast, calcitonin administration did not significantly affect 25(OH)D plasma levels. Collectively, these data suggest that calcitonin and calcium are independent regulators of 1,25(OH)2D production and that calcitonin stimulates intestinal absorption of calcium, by increasing circulating levels of 1,25(OH)2D.

Animals↗
PubMed1985

Health care, public policy and the courts: black health status as a civil rights issue.

In the U.S.A. serious differences in the health status between black and white citizens continue to exist. Black Americans are less healthy and receive less health care than while Americans. The discrimination is examined as a civil rights issue with focus on both the policy and judicial perspectives of the application of Title VI of the Civil Rights Act of 1964 and the implementative effects of the Hill-Burton Act of 1946. The application, and compliance and enforcement, of civil rights to health care is complicated by a captivity process involving Federal agencies, by corporate medical rights emphasizing a business approach to health care, and by a liberal pluralistic political arena in which certain influential groups prevail over others. In order for black health status and care to improve in the U.S.A., blacks must continue to utilize the judicial system to seek redress of health care inequities. Second, they must utilize their demonstrated political power to demand better treatment from the medical establishment.

Black or African American↗
PubMed1985

Evaluation of the Andersen viable impactor for single stage sampling.

A modified use of the 6-stage Andersen viable sampler for single stage sampling is described. Although size distribution data are not obtainable with such a sampler, it has utility as a simple and convenient method for estimating the total concentration of viable airborne microorganisms. The method was compared in the field to the standard Andersen sampler and a previously described method for single plate sampling. Over a wide range of airborne fungal concentrations (10-3000 CFU/m3), the modified sampler was found to be superior to the previous method and comparable to the standard Andersen sampler (in terms of both precision and accuracy), for estimating total airborne fungal concentration.

Air Microbiology↗
PubMed1984

Influence of migratory blood cells on the attachment of tumor cells to vascular endothelium.

The purpose of this study was to determine whether the presence of migratory blood cells in association with tumor emboli had the capacity to alter the attachment of tumor cells to vascular endothelium. Highly metastatic RT7-4bs rat hepatocarcinoma cells were labelled with [125I]UdR before being allowed to form mixed cellular spheroids incorporating resident peritoneal macrophages, activated peritoneal macrophages, polymorphonuclear leukocytes, splenic T lymphocytes, or splenic B lymphocytes derived from both normal and tumor-bearing animals. The presence of polymorphonuclear leukocytes or activated macrophages led to a considerable increase in the number of tumor cells attaching to endothelial cell monolayers in vitro. The presence of T or B lymphocytes from either normal or tumor-bearing rats was without effect on tumor attachment to endothelium. Increased tumor cell retention in the lungs was evident for mixed spheroids containing tumor cells and polymorphonuclear leukocytes compared to homotypic tumor spheroids composed of tumor cells alone. Furthermore, preinjection of polymorphonuclear leukocytes intravascularly or inoculation of tumor cells as heterotypic spheroids containing polymorphonuclear leukocytes increased lung colony formation over that obtained after inoculation of tumor cells alone. Several simple sugars were tested for their ability to block tumor cell, polymorphonuclear leukocyte or activated macrophage binding to endothelium in vitro. The results indicate that the glycosylated cell surface components mediating tumor cell attachment to endothelium are not identical with those mediating attachment of either polymorphonuclear leukocytes or activated macrophages. Medium conditioned during mixed spheroid formation was without effect on tumor cell attachment to endothelium. We conclude that the presence of some, but not all classes of leukocytes can modulate tumor cell attachment to vascular endothelium, an effect most likely mediated by a mechanism involving direct contact between the leukocytes and the endothelial cell monolayer.

Animals↗
PubMed1984

Epidemiological-environmental study of lead acid battery workers. I. Environmental study of five lead acid battery plants.

Industrial hygiene measurements were taken at five lead acid battery plants. The average of all personal samples for H2SO4 was 0.18 mg/m3 with a range of "nondetectable" to 1.7 mg/m3. Highest levels of acid were found in the charging and forming areas of the plants. Stibine and arsine were also detected in the charging and forming areas (means = 0.44 and 0.042 mg/m3, respectively). Arsenic in particulate form was also detected, but levels were low (means = 0.00083 mg/m3). The average mass median aerodynamic diameter of the acid mist as measured by cascade impactors was approximately 5 micron. Air lead results were variable with an overall average of 0.072 mg/m3 and a standard deviation of 0.11 mg/m3.

Air Pollutants, Occupational↗
PubMed1984

Epidemiological-environmental study of lead acid battery workers. II. Acute effects of sulfuric acid on the respiratory system.

Two hundred and twenty-five (225) workers in five lead acid battery plants were administered a questionnaire containing work-related symptoms, underwent spirometry, and had personal samples for H2SO4 taken over the shift. Most personal samples were less than 1 mg/m3 H2SO4. Mass median aerodynamic diameter of H2SO4 from area samples in the formation areas was 2.6-10 micron. Workers with a higher exposure to acid did not have an increased rate of acute work-related symptoms. Changes in pulmonary function over the shift were not related to levels of airborne lead or airborne acid, sex, age, or smoking status. In acclimated workers, there is no evidence of acute symptoms or reductions in pulmonary function over the shift at concentrations less than 1 mg/m3.

Adult↗
PubMed1984

Epidemiological-environmental study of lead acid battery workers. III. Chronic effects of sulfuric acid on the respiratory system and teeth.

The effects of long-term exposure to sulfuric acid mist on the teeth and respiratory system were studied in 248 workers in five plants manufacturing lead acid batteries. The prevalence of cough, phlegm, dyspnea, and wheezing as determined by questionnaire were not associated with estimates of cumulative acid exposure. There was only one case of irregular opacities seen on the chest radiographs. There was no statistically significant association of reduced FEV1, peak flow, FEF50, and FEF75 with acid exposure although the higher exposed group had lower mean values. FVC in the high exposure group showed a statistically significant reduction compared to the low exposure group, but there was no significant association when exposure was analyzed as a continuous variable. The ratio of observed to expected prevalence of teeth etching and erosion was about four times greater in the high acid-exposure group. The earliest case of etching occurred after 4 months exposure to an estimated average exposure of 0.23 mg/m3 sulfuric acid.

Adult↗
PubMed1984

Aflatoxin in respirable airborne peanut dust.

Laboratory shelling and pilot handling operations were conducted to determine if peanut dust generated by such operations contained significant amounts of aflatoxin. Air samples were collected from points of highest dust concentration. No aflatoxin B1 was detected in dust from uncontaminated lots. Aflatoxin B1 levels of 700 ppb and 7.6 ng/m3 were detected from highly contaminated lots. The contamination of the dust was directly proportional to the contamination of the lots handled or shelled. In the shelling tests, the level of contamination of the dust samples was about one-ninth of the level of contamination of the peanuts. In the handling tests, the level of contamination of the dust samples was about half the contamination level of the peanuts. These results indicate that most of the contaminated dust was probably removed by handling operations prior to shelling. Although workers are not routinely exposed to such levels of contaminated dust, these findings suggest the need for a more thorough study of peanut dust during handling or processing of contaminated peanuts.

Aflatoxin B1↗
PubMed1984

Antibiotic prophylaxis in hysterectomy--cefotaxime compared to ampicillin-tinidazole.

The role of prophylactic cefotaxime and a combination of ampicillin and tinidazole was assessed in 201 patients undergoing hysterectomy. One hundred and twenty-five patients were evaluated in the abdominal hysterectomy group and 46 patients completed the protocol after vaginal hysterectomy. Patients were allocated randomly to receive either (1) no prophylactic antibiotic, (2) cefotaxime peroperatively for 24 h or (3) ampicillin/tinidazole peroperatively for 24 h. Both cefotaxime and ampicillin/tinidazole reduced the septic complication rate in abdominal and vaginal hysterectomy. Efficacy was most evident in reducing early urinary infections after abdominal hysterectomy (0.001 less than P less than 0.01). Cefotaxime and ampicillin/tinidazole were equally effective and no significant side-effects were demonstrated. Cefotaxime is recommended as a safe and effective agent for hysterectomy prophylaxis.

Adult↗
PubMed1984

Hand Test and the High School Personality Questionnaire: structural analysis.

The Hand Test and the High School Personality Questionnaire were administered to 15 boys and 15 girls in Grades 9 and 10 transferred to an alternative school for acting-out behavior. They were of average intelligence. Several significant correlations between Hand Test and High School Personality Questionnaire variables were noted. Results are discussed in reference to Structural Analysis.

Acting Out↗