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Biomedical subjects

C E Lawrence

Publications and source records attributed to C E Lawrence.

At least 73 records · Page 4Linked to original sources
PubMed1985

Prothrombin time proficiency testing: a robust grading method.

A robust two-way analysis of variance technique was applied to determine simultaneously the effects of method and thromboplastin on prothrombin time. A new approach to outlier detection for two-way analysis of variance was used. Focusing on the underlying error structure improved the uniformity of the grading procedure in the hematology proficiency testing program of the New York State Department of Health. The logarithm-transformed scale produced constancy of error variance and resulted in uniformity of the acceptable spread of data. The common variance was lower than that obtained by previous methods and allowed for a narrower acceptable range of reported prothrombin times by reducing the inflated standard deviation, thus improving the efficiency of the grading procedure. For proficiency testing, no advantage was found in the use of either a common thromboplastin or freeze-dried, coumadinized patient plasmas rather than artificially depleted commercial plasmas, except for special purposes.

Automation↗
PubMed1985

Maximum likelihood estimation of subsequence conservation.

A statistical method is presented for comparing protein sequences by partitioning the polymers and estimating each subsegment's degree of conservation. Conservation is measured as a function of the number of transitions occurring in the underlying time homogeneous Markov process assumed to govern amino acid mutations. The Markovian assumption also permits estimation of the ancestral sequence. Partitioning and estimation are carried out via maximum likelihood. The method is contrasted with the commonly utilized percent homology measure. A moving likelihood ratio plot to aid in identifying regions of high conservation is suggested as an analogue to moving hydrophobicity plots. An application is presented which identifies highly conserved regions in thymidylate synthase from L. casei and E. coli.

Amino Acid Sequence↗
PubMed1985

Mortality patterns of New York State Vietnam Veterans.

Mortality odds ratios (MORs) comparing veterans with Vietnam service who died in New York State to veterans of the Vietnam era with no Vietnam service were estimated (N = 1,496). The most elevated MORs and their confidence intervals were non-motor vehicular injuries of transport (MOR = 2.18, (1.19, 3.96)), other accidents and burns (MOR = 1.37, (0.95, 1.98)), and homicide (MOR = 1.59, (0.86, 2.94).

Accidents↗
PubMed1984

Polychlorinated biphenyls: influence on birthweight and gestation.

Fifty-one infants born to women employed at two capacitor manufacturing facilities with a history of high exposure to polychlorinated biphenyls (PCBs) had a mean birthweight of 153 grams less than that of 337 infants born to women who had worked in low-exposure areas (90 per cent confidence interval, -286 to -20 g); mean gestational age was 6.6 days shorter in the high-exposure infants (90 per cent CI, -10.3 to -2.9 days). After adjusting for gestational age, the difference in birthweight was markedly reduced, indicating that the observed reduction in birthweight was due mainly to shortening of gestational age in the high-exposure group.

Aroclors↗
PubMed1984

Trihalomethanes in drinking water and human colorectal cancer.

The relation of trihalomethanes (THM) to colorectal cancer was evaluated. A total of 395 colorectal cancer deaths among white women teachers in New York State was compared to an equal number of deaths of teachers from noncancerous causes. Cumulative chloroform (CHCl3) exposure was estimated by the application of a statistical model to operational records from the individual water treatment facilities that served the home and work addresses of each study subject during the 20 years prior to death. The odds of exposure to a surface source containing little or no THM was no greater for cases than for controls. The odds ratio = 1.07; the 90% confidence interval = 0.79-1.43; and the P = .68. The distribution of CHCl3 exposure was not significantly different between cases and controls (rated by Wilcoxon signed rank statistic = -0.52; P = .60). No effect of cumulative CHCl3 exposure on outcome was seen in a logistic analysis controlling for average source type, population density, marital status, age, and year of death (likelihood ratio test statistic = 0.047; P = .83).

Aged↗
PubMed1983

Breast cancer and oral contraceptive use: a case-control study.

The effect of oral contraceptive (OC) use was examined among parous breast cancer cases diagnosed at less than or equal to 45 years of age, and in two different general population control groups of parous women. The primary analysis compared 278 cases with 520 controls. In the secondary analysis, a subgroup of 190 cases were compared with 190 controls from another reference group. In both analyses, ever use of OC, duration of OC use, and OC use prior to first pregnancy showed no significant association with breast cancer risk. Also in both analyses, in women with prior benign breast disease OC use increased the risk of breast cancer, although this finding was statistically significant only in the larger group used in the primary analysis.

Adult↗
PubMed1982

The effect of cortisol on porcine articular tissues in organ culture.

(1) The effects of hydrocortisone succinate (1.0--0.01 micrograms HC/ml of medium) on porcine articular tissues in organ culture have been studied by histological and biochemical methods. (2) 1.0 and 0.1 micrograms HC/ml considerably inhibited the severe breakdown of matrix that occurs in living and dead cartilage explained in contact with synovial tissue. (3) The depletion of matrix in living cartilage cultivated in the same dish as but not in contact with synovial tissue, is much diminished when the medium contains 1.0 or 0.1 micrograms HC/ml. (4) Cartilage grown in the used medium of synovial tissue loses both proteoglycan and hydroxyproline; the addition of HC to the used medium has little (1.0 microgram HC/ml) or 0.1 microgram HC/ml) no inhibitory effect. If, however, the used medium is from synovial tissue that has been cultured in the presence of 1.0 or 0.1 micrograms HC/ml, loss of proteoglycan and collagen from the cartilage is much reduced. (5) In isolated cartilage in normal medium there is outgrowth of cells from the cut surface and some loss of proteoglycan and collagen; outgrowth is completely, and loss of matrix components partially suppressed by 1.0 micrograms HC/ml. (6) Isolated synovial tissue cultured in normal medium shrinks to about one-third of its original size, loses much of its collagen and secretes neutral metallo-proteinases into the medium; in the presence of 1.0 microgram HC/ml these changes are largely prevented. The explants also secrete an inhibitor of metallo-proteinases the production of which is not reduced by HC.

Animals↗
PubMed1981

Diagnostic sensitivity bias -- an epidemiologic explanation for an apparent brain tumor excess.

Preliminary data showing over-representation of the Eastman Kodak Company (Rochester) on death certificates of brain tumor patients, and higher risk for older workers when compared to the general population, led to a case-control epidemiologic study. Chemical exposure histories of 56 workers with brain tumors were compared with those of other Kodak employees. No differences were found in exposure to a variety of chemicals. In addition, employees with brain tumors were compared to other upstate New York brain tumor patients; there was no difference in histology. However, the Kodak employees had diagnoses more frequently confirmed by histologic examination and more thorough diagnostic studies. Thus, the apparent initial excess of diagnosed tumors may have resulted from a "diagnostic sensitivity bias" arising from more complete medical evaluation of Kodak employees.

Brain Neoplasms↗
PubMed1980

Tonsillectomy and childhood Hodgkin's disease.

The relation between previous tonsillectomy and Hodgkin's disease was examined in a case-control study involving 81 histologically confirmed childhood cases and two sibling control groups. When cases were compared with age-matched sibling controls a significant association (p < 0.02), with a risk of 2.7, was observed for children who had undergone tonsillectomy. A significant association (p < 0.01), with a relative risk of 2.5, was also shown when all siblings were used for comparison. History of hospital admissions, age at tonsillectomy, Rye histological subtype, birth order, and sibship size did not appear to modify the effect of this operative procedure on the risk of Hodgkin's disease.

Adult↗
PubMed1980

A systems model for burn care.

The problem of projecting the number of tertiary service beds needed by a population is materially different for rare events than for medical events of more common occurrence. Demand for inpatient burn treatment services has been carefully measured in 57 countries in New York State. A survey provided data describing the rate of ocurrence, severity, and average length of stay for 5,791 hospitalized burn patients. Existing planning formulae which were designed for events of common occurrence were found to project conditions of overflow and underutilization incompletely when applied to regional burn units. Objective planning models designed specifically for intensive burn care were therefore developed. These models show that there is no number of intensive care burn beds which will provide both reasonably high occupancy and reasonable assurance of meeting the normally erratic demand of a small system. Conditions of overload and underutilization are inevitable and therefore planning efforts should be directed at minimizing these impacts. If all of the regional burn treatment facilities are regarded as components of a well-integrated statewide system, a much more effective efficient and economic service will result.

Burns↗
PubMed1980

Relationship of hair dye use, benign breast disease, and breast cancer.

An epidemiologic case-control study of 118 breast cancer patients and 233 controls was conducted to test the hypothesis that hair dyes are related to breast cancer. Matched controls were selected by "random digit dialing," and all epidemiologic data were collected by telephone interviews. No overall association was detected. On a prospective basis, the interaction between hair dye exposure and six variables known to be risk factors for breast cancer then were examined: previous benign breast disease (BBD), "ever" versus "never" pregnant, age at first pregnancy, menopause induced by operation, age at menarche, and education. A statistically significant increased risk of breast cancer was found for women with a history of BBD and exposure to hair dyes as compared to women with BBD but no hair dye exposure: The relative risk (RR) was 4.5, and the 95% confidence intervals (C) were 1.20 and 15.78. A total of 24 women (19 patients and 5 controls) reported a history of BBD and hair dye use. Further analysis revealed a significant association between hair dye use and breast cancer among women 40-49 years of age (RR = 3.33; 95% CI: 1.1 and 10.85) and a highly significant (P = 0.0008) dose-response relationship among women who used hair dyes for changing their natural color as opposed to covering gray hair. The numbers of patients and controls included in this study were small and several hypotheses were tested. Additional epidemiologic studies are needed before firm conclusions can be reached concerning the nature of these associations.

Adult↗
PubMed1978

Estimated effect of breast self-examination and routine physician examinations on breast-cancer mortality.

We examined the effects of breast self-examination and breast examination by physicians on the stage of breast cancer at diagnosis. Clinical and pathological-staging information was compared to interview data on method of initial detection of 293 women. Tumors were detected in clinical Stage I 53.8% of the time when the detection method was routine physician examination, 37.7% when it was self-examination and only 27.0% when detection was accidental. Sixty-nine per cent of women practicing self-examination at the time of diagnosis discovered their tumor by this method. Differences were less apparent when pathological stage was considered. Tumors found during routine examination of the breast averaged 6.1 mm smaller in diameter than those discovered accidentally. We estimate that breast-cancer mortality might be reduced by 18.8% to 24.4% through self-examination or routine physician examination, respectively.

Breast↗
PubMed1976

Fertility patterns after discontinuation of use of oral contraceptives.

Investigation of the fertility-rate after discontinuation of use of oral contraceptives shows that the monthly rate consistently follows an oscillatory pattern. This pattern appears to be unique to women who have discontinued the use of oral contraceptives. It may result from synchronisation of a previously unrecognised natural cycle, rebound changes in the reproductive system following steroidal contraception, or an infertile period associated with early intrauterine mortality.

Adult↗
PubMed1975

REALPOP: a mathematical model for resource allocation in population programs-results from a test in the Dominican Republic.

The structure of a computerized mathematical model for resource allocation in population programs (REALPOP) and its application to the Dominican Republic's national family planning program are described. The model integrates demographic and management science approaches in the analysis of resource allocation, program planning, goal evaluation, and growth strategies of a family planning program. It is designed primarily to aid administrative decision-makers. The Dominican National Population and Family Council (NPFC) established a goal of reducing the crude birth rate from its 1968 level of 48 per thousand population to 28 per thousand in 15 years. Further, the program has established a clear set of program plans and alternatives. This study investigates the implication of these plans for the program's stated goals.

Contraceptives, Oral↗