Search PubMed⌕ Search

Biomedical subjects

J J Collins

Publications and source records attributed to J J Collins.

At least 73 records · Page 4Linked to original sources
PubMed1999

Mortalities of workers at the Nitro plant with exposure to 2-mercaptobenzothialzole.

OBJECTIVES: An update of a study of workers exposed to 2-mercaptobenzothiazole (MBT) at a rubber chemicals plant in Nitro, West Virginia is reported. The earlier study found high rates of lung cancer, prostate cancer, and bladder cancer in these workers who also had potential exposure to 4-aminobiphenyl (PAB), a potent bladder carcinogen. METHODS: This cohort mortality study examines the mortalities of 1059 full time white male production workers employed at the plant from 1955 to 1977. A detailed exposure assessment was done on the 600 workers with exposure to MBT. Nine years of additional follow up to the previous study are added. RESULTS: It was found that MBT workers have expected rates of lung (standardised mortality ratio (SMR) = 1.0 95% confidence interval (95% CI) 0.7 to 1.5) and prostate (SMR = 0.9, 95% CI 0.2 to 2.3) cancer. There was an excess of bladder cancer among MBT workers who had definite exposure to PAB (SMR = 27.1, 95% CI 11.7 to 53.4), and MBT workers with potential exposure to PAB (SMR = 4.3, 95% CI 1.4 to 10.0). However, there were no deaths from bladder cancer among workers with no exposure to PAB (SMR = 0.0, 95% CI 0.0 to 24.7), although there were only 0.2 deaths expected. CONCLUSIONS: The potential confounding of exposure to an unknown portion of PAB in the MBT workers makes it impossible to evaluate risk of bladder cancer in this population at this time. However, exposure to MBT does not seem to increase the risk of most cancers including cancers of the lung and prostate.

Aged↗
PubMed1998

A theory for controlling cell cycle dynamics using a reversibly binding inhibitor.

We demonstrate, by using mathematical modeling of cell division cycle (CDC) dynamics, a potential mechanism for precisely controlling the frequency of cell division and regulating the size of a dividing cell. Control of the cell cycle is achieved by artificially expressing a protein that reversibly binds and inactivates any one of the CDC proteins. In the simplest case, such as the checkpoint-free situation encountered in early amphibian embryos, the frequency of CDC oscillations can be increased or decreased by regulating the rate of synthesis, the binding rate, or the equilibrium constant of the binding protein. In a more complex model of cell division, where size-control checkpoints are included, we show that the same reversible binding reaction can alter the mean cell mass in a continuously dividing cell. Because this control scheme is general and requires only the expression of a single protein, it provides a practical means for tuning the characteristics of the cell cycle in vivo.

Animals↗
PubMed1998

Mitral valve repair in cardiomyopathy.

BACKGROUND: Volume overload secondary to mitral regurgitation (MR) in cardiomyopathy is considered critical in the pathogenesis of subsequent ventricular dysfunction. Open mitral valve repair (OMVP) is hypothesized to improve symptomatology and ventricular function by reducing the volume overload of the left ventricle. METHODS AND RESULTS: All patients who underwent OMVP with a left ventricular ejection fraction (EF) of < 0.30 (n = 81) from 1984 through 1997 were reviewed (1 patient was lost to follow-up). Fifteen operations (18.5%) were repeat operations after previous coronary artery bypass graft surgery. Preoperative and postoperative EFs and NYHA class were compared. Survival probabilities were calculated, and multivariate analysis was performed. The average age of all patients was 67.1 years (range, 41 to 83 years). Mean follow-up was 1.7 years (range, 2 months to 8.5 years). The most common mitral repair was ring annuloplasty. Sixty-two patients (77%) had concomitant coronary artery bypass graft surgery. The surgery mortality rate was 11% (9 of 81); 6 of these 9 patients were > 70 years old. The overall Kaplan-Meier survival probability rate at 1, 2, 3, 4, and 5 years was 0.73, 0.68, 0.58, 0.50, and 0.38, respectively. EF improved significantly (0.24 to 0.32; P < 0.0001), as did the NYHA class (3.2 to 1.6; P < 0.0001), at follow-up. There was no difference in late survival between patients with an EF of < 0.20 (21 patients) and those with an EF between 0.20 and 0.30 (P = NS). Risk factors for death included heart failure and old age. CONCLUSIONS: OMVP for MR in the setting of ischemic cardiomyopathy and low EF appear to improve ventricular function, medium-term patient symptomatology, and survival.

Adult↗
PubMed1998

It's a small world.

Explore the source record for details and available documents.

Games, Experimental↗
PubMed1998

Twenty-year follow-up of the Hancock modified orifice porcine aortic valve.

BACKGROUND: The entire experience with the Hancock modified orifice porcine bioprosthetic aortic valve from 1976 to 1996 at the Brigham and Women's Hospital has been reviewed. Eight hundred forty-three patients received this valve with a total follow-up of 61,114 months, and a mean follow-up of approximately 72.5 months. There were 490 men and 353 women, and the predominate lesion was aortic stenosis (636 of 843); 365 (43%) patients required a concomitant coronary artery bypass graft operation. METHODS: Patients were followed prospectively in the Brigham Cardiac Valve Data Registry, and the data were analyzed by the SAS statistical package, using actuarial survival curves and incidence per patient-year of morbidity and mortality. RESULTS: The overall operative mortality was 45 of 843 (5.3%) with 23 of 478 (4.8%) for isolated aortic valve replacement and 22 of 365 (6.0%) for aortic valve plus coronary artery bypass graft operation. The major morbidity of this valve was structural valve dysfunction, which was significantly related to the age of the patient in whom the valve was placed. Actuarial probability of freedom from structural valve degeneration at 5, 10, and 15 years overall was 99%+/-1%, 79%+/-3% and 57%+/-4%, at 15 years, respectively. In patients younger than 50 years, freedom from structural valve dysfunction was 16%+/-8%, whereas in the age group older than 70 years it was 87%+/-5% (p = 0.0005). Thromboembolism at 10 and 15 years was 81%+/-3% overall, 84%+/-2% in patients in normal sinus rhythm, and 57%+/-13% in patients with chronic atrial fibrillation. CONCLUSIONS: The Hancock modified orifice aortic valve, despite its more complicated fabrication, has been a reliable porcine bioprosthetic valve and can be used reliably in patients older than 70 years because of its low structural valve degeneration rate, and protection from stroke and anticoagulant hemorrhage in those patients in sinus rhythm.

Actuarial Analysis↗
PubMed1998

Biomechanical gait alterations independent of speed in the healthy elderly: evidence for specific limiting impairments.

OBJECTIVES: It is not known whether changes in the biomechanics of elderly gait are related to aging per se, or to reduced walking speed in this population. The goals of the present study were to identify specific biomechanical changes, independent of speed, that might impair gait performance in healthy older people by identifying age-associated changes in the biomechanics of gait, and to determine which of these changes persist at increased walking speed. DESIGN: Stereophotogrammetric and force platform data were collected. Differences in peak joint motion (kinematic) and joint moment and power (kinetic) values between healthy young and elderly subjects at comfortable and increased walking speed were measured. SETTING: A gait laboratory. SUBJECTS: Thirty-one healthy elderly (age 65 to 84 years) and 31 healthy young adult subjects (age 18 to 36 years), all without known neurologic, musculoskeletal, cardiac, or pulmonary problems. MAIN OUTCOME MEASURES: All major peak kinematic and kinetic variables during the gait cycle. RESULTS: Several kinematic and kinetic differences between young and elderly adults were found that did not persist when walking speed was increased. Differences that persisted at both comfortable and fast walking speeds were reduced peak hip extension, increased anterior pelvic tilt, and reduced ankle plantarflexion and ankle power generation. CONCLUSION: Gait performance in the elderly may be limited by both subtle hip flexion contracture and ankle plantarflexor concentric weakness. Results of the current study should motivate future experimental trials of specific hip flexor stretching and ankle plantarflexor concentric strengthening exercises to preserve and potentially improve walking performance in the elderly.

Adolescent↗
PubMed1998

Age-related changes in the initiation of gait: degradation of central mechanisms for momentum generation.

OBJECTIVE: To investigate cross-sectionally age-related changes in the expression and biomechanical efficiency of the gait-initiation motor program. DESIGN: Case-control study. PARTICIPANTS AND SETTING: Twenty healthy young research subjects and 20 healthy elderly subjects who volunteered from the community participated in this study at a university research laboratory. MAIN OUTCOME MEASURES: Participants performed gait-initiation trials at three speeds from a starting position on a force platform while ground reaction force data, 3-D motion analysis data, and electromyographic data were collected. Measures included: latency of tibialis anterior (TA) activation and soleus (SOL) and gastrocnemius (GA) inhibition, magnitude of center of pressure (COP) displacement, magnitude of momentum generated, and final walking velocity. RESULTS: The expression of the central motor program governing gait initiation, as evidenced by the invariant timing between TA activation and SOL/GA inhibition, was seen in both the young and elderly populations, but the frequency was diminished in the latter group. The momentum-generating capacity of the COP shift mechanism was present but significantly diminished in the elderly population. CONCLUSIONS: These findings suggest that the central nervous system uses stable, efficient mechanisms for dealing with the inherent instability of upright bipedalism and that the integrity of these mechanisms degrades with aging.

Adolescent↗
PubMed1998

Home care for the dying child. A parent's perception.

OBJECTIVES: To identify the benefits and difficulties of families caring for a dying child at home and to assess the parents' adjustment following their child's death. METHOD: Semi-structured interview and questionnaire. RESULTS: The benefits of home versus hospital care included greater freedom, more privacy and less disruption to family life, and that caring for the child was a positive experience for most families. Despite this experience many families expressed many fears and concerns about the symptomatic care of their children and requested more support. DISCUSSION: Hospital-based treatment teams have a responsibility to ensure adequate support can be provided before home care is recommended for dying children. The experience of home-based palliative care reported by these parents and their suggestions for change will assist all who care for dying children and to improve services supporting home-based palliative care.

Adolescent↗
PubMed1998

Mortality update of workers exposed to acrylonitrile in The Netherlands.

A retrospective cohort study investigating the cause-specific mortality patterns of 2842 workers occupationally exposed to acrylonitrile for at least 6 months before 1 July 1979 was updated. The comparison group consisted of 3961 workers from a nitrogen fixation plant during the same time interval. Industrial hygiene assessments quantified past exposure to acrylonitrile, the use of personal protective equipment, and exposure to other potential carcinogenic agents. All 6803 workers were followed for mortality until 1 January 1996. The follow-up was almost complete (99.6%), and for 99.3% the cause of death was ascertained. Age distribution, follow-up period, and temporal changes in background mortality rates were adjusted for in calculations of standardized mortality ratios for separate causes of death. Cumulative dose-effect relations were determined for 3 exposure categories and 3 latency periods. The results showed that, although cancer mortality fluctuated slightly, no cancer excess seems related to exposure to acrylonitrile.

Acrylonitrile↗
PubMed1998

Review and meta-analysis of studies of acrylonitrile workers.

Twenty-five epidemiologic studies of acrylonitrile workers were reviewed and subjected to meta-analytic techniques in this study to assess the findings for 10 cancer sites. The analyses indicate that workers with acrylonitrile exposure have essentially null findings for most cancers, including lung [meta-relative risk (mRR) 0.9, 95% confidence interval (95% CI) 0.9-1.1], brain (mRR 1.2, 95% CI 0.8-1.7), and prostate (mRR 1.0, 95% CI 0.7-1.4) cancers. Bladder cancer rates were elevated (mRR 1.8, 95% CI 1.0-3.4), but the excess was not dose-related and was limited to plants with aromatic amines. Therefore, the bladder cancer excess is unlikely to be related to acrylonitrile exposure. Some evidence of publication bias was found in the examined literature, but the bias did not have a significant impact on risk estimates for individual cancers. It was concluded that the available studies do not support a causal relation between acrylonitrile exposure and cancer.

Acrylonitrile↗
PubMed1997

Issues in the linkage of alcohol and domestic violence services.

It is well established that alcohol is a risk factor for male against female domestic violence. Some evidence also suggests that some women victims of domestic violence develop substance abuse problems in response to their victimization. Although interpretations vary regarding the exact nature of the relationship of substance abuse and domestic violence offending and victimization, there is evidence that linking substance abuse and domestic violence services could have a positive impact on batterer cessation and victim support services. Currently, however, service linkage for the two problems is rare. There are major barriers to linkage of substance abuse and domestic violence services, including philosophical differences of treatment perspective between program types and structural impediments that make linkage difficult. The chapter discusses the barriers to linkage, examines potentially useful linkage models, and suggests the next steps to examine the feasibility of linking services for the two problems.

Alcoholism↗
PubMed1997

Axilloaxillary cardiopulmonary bypass: a practical alternative to femorofemoral bypass.

BACKGROUND: Peripheral arterial and venous cannulation for cardiopulmonary bypass is used increasingly for patients undergoing minimally invasive cardiac operations, complex reoperations, or repair of aortic dissection or aneurysm, and for patients with extensive arteriosclerotic aortic disease in whom aortic cannulation is a prohibitive embolic risk. The common femoral artery and vein are most commonly used for peripheral cannulation, but these sites may be predisposed to complications, primarily because the femoral vessels are commonly involved with arteriosclerotic disease. We have recently begun to use the axillary artery and axillary vein as alternative cannulation sites, achieving full cardiopulmonary bypass, providing antegrade aortic flow, and avoiding many of the complications associated with other sites. METHODS: Seven patients with peripheral vascular or aortic disease, or both, prohibiting safe aortic or femoral cannulation underwent cardiopulmonary bypass through axillary artery and axillary vein cannulation, approached through a small single subclavicular incision. RESULTS: All patients were successfully cannulated and axilloaxillary cardiopulmonary bypass was possible without the need for additional cannulas. All axillary vessels were closed primarily without complication. CONCLUSION: For an expanding population of patients with peripheral vascular and aortic disease, axilloaxillary bypass is a safe and practical alternative to aortic or femoral cannulation.

Aged↗
PubMed1997

Cancer mortality among workers with benzene exposure.

We updated a cohort mortality study of 4,172 workers at a chemical plant to examine cancer mortality among workers exposed to low levels of benzene. Overall mortality [standardized mortality ratio (SMR) = 1.0; 95% confidence interval (CI) = 0.9-1.1] and cancer mortality (SMR = 1.0; 95% CI = 0.8-1.3) rates were at expected levels for production workers with benzene exposure. We observed elevated, albeit imprecise, rates of leukemia (SMR = 2.3; 95% CI = 0.7-5.3) and multiple myeloma (SMR = 2.3; 95% CI = 0.7-9.4) in this group of workers. The leukemias and multiple myelomas occurred predominantly among workers 20 or more years after first exposure. The leukemias were not restricted to acute myelogenous subtypes, and they occurred predominantly among workers hired before 1950 at exposure levels lower than previously reported. Leukemia (SMR = 1.3; 95% CI = 0.6-2.4) and multiple myeloma (SMR = 1.2; 95% CI = 0.3-2.9) rates were at expected levels among maintenance workers with intermittent high exposure to benzene. These findings provide evidence on both sides of the debate about whether low benzene exposure increases the risk of multiple myeloma and all types of leukemia.

Benzene↗
PubMed1997

Evaluation of lymphopenia among workers with low-level benzene exposure and the utility of routine data collection.

Whether low-level benzene exposure produces health effects is controversial. We used routinely collected data from our medical/industrial hygiene system to study 387 workers with daily 8-hour time-weighted exposures averaging 0.55 ppm. The cross-sectional repeated survey design included 553 unexposed workers. Lymphopenia is considered to be the earliest and most sensitive indicator of benzene toxicity. We found no increase in the prevalence of lymphopenia among benzene-exposed workers (odds ratio, 0.6; 95% confidence interval, 0.2 to 1.8), taking into account smoking, age, and sex. There also was no increase in risk among workers exposed 5 or more years (odds ratio, 0.6; 95% confidence interval, 0.2 to 1.9). Examination of other measures of hematotoxicity, including mean corpuscular volume and counts of total white blood cells, red blood cells, hemoglobin, and platelets, produced similar results. We conclude that risk of lymphopenia and other early indicators of hematotoxicity are not increased among workers in this study who were exposed to low levels of benzene.

Adolescent↗
PubMed1997

An updated meta-analysis of formaldehyde exposure and upper respiratory tract cancers.

In this study, we summarize 47 epidemiologic studies related to formaldehyde exposure and use meta-analytic techniques to assess findings for cancers of the lung, nose/nasal sinuses, and nasopharynx. Our analyses indicate that workers with formaldehyde exposure have essentially null findings for lung cancer and a slight deficit of sinonasal cancer. Nasopharyngeal cancer rates were elevated moderately in a minority of studies. Most studies, however, did not find any nasopharyngeal cancers, and many failed to report their findings. After correcting for underreporting, we found a meta relative risk of 1.0 for cohort studies. Case-control studies had a meta relative risk of 1.3. Our review of the exposure literature indicated that the nasopharyngeal cancer case-control studies represented much lower and less certain exposures than the cohort studies. We conclude that the available studies do not support a causal relation between formaldehyde exposure and nasopharyngeal cancer. This conclusion conflicts with conclusions from two previous meta-analyses, primarily because of our consideration of unreported data.

Carcinogens, Environmental↗