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Biomedical subjects

O Horwitz

Publications and source records attributed to O Horwitz.

At least 19 recordsLinked to original sources
PubMed1992

Francis Clark Wood.

Explore the source record for details and available documents.

Education, Medical, Graduate↗
PubMed1986

Arterial intimal embrittlement. A possible factor in atherogenesis.

Sections of aorta, coronary artery, basilar artery and vena cava were collected at autopsy. Macroscopically normal intimal specimens were removed by stripping. Intimal collagen was measured as hydroxyproline. Intimal film embrittlement was measured in vitro by a bursting volume distensibility test developed in our laboratory. There was an average increase of over 100% in the collagen content of apparently lesion-free human arterial intima on aging over a fifty-year period. This includes an increase of 113% for aortic intima, 49% increase for coronary artery intima, and an increase of 158% in collagen in basilar artery intima. In contrast the collagen level in the vena caval intima decreases on aging, by 42% in fifty years. The large increase in collagen in arterial intima is accompanied by a large increase in intimal embrittlement. The decreasing collagen content of the venous intima on aging results in increased distensibility. Increased aortic intimal film embrittlement (lower distensibility) correlates with age (R = 0.699), but even better with intimal collagen (R = 0.911), suggesting that aortic intimal collagen level is a more important determinant of intimal embrittlement than age. Men, older than 55, have significantly higher aortic intimal collagen levels than women. Embrittlement of arterial intima should make it more susceptible to injury under the pulsatile pressure of the blood. Decreased venous intimal collagen and greater distensibility on aging could be factors in the development of venous valvular insufficiency and varicose veins. However, our study of veins was performed primarily as a control in this instance. Fundamental elements in the atherogenic process are increased intimal collagen, increased intimal brittleness, endothelial injury, followed by intimal cell proliferation. In the vena caval intima on aging there is decreased collagen, increased intimal distensibility, no injury due to increased pulse or blood pressure, and, therefore, no cell proliferation and no intimal lesion.

Adolescent↗
PubMed1979

Public health aspects of cancer deaths.

In 1976, the toll of cancer in Denmark (5 million inhabitants) was 12,481 deaths, or 23% of deaths from all causes. Seven manifestations accounted for more than half of the cancer deaths, namely lung (19%), breast (9%), stomach (7%), colon (9%), rectum (5%), pancreas (6%) and prostate (5%). The median age of the cancer patients was 70 years, ranging from 65 years for breast cancer patients to 75 years for those with prostate cancer. Cancer caused a reduction in the patients' normal life-span; it totalled 182,486 years for all the dead patients, 37% of which were in productive age. The future caseload was projected from the time trend for the years 1968-76. During the following five years an annual increase by 200 deaths is expected. The trend differs between the seven major manifestations, since some will increase and others will stabilize or decrease. When case reports are combined with mortality data, survival tables can be produced. Follow-up surveys of the patient's health, combined with modern data processing, can produce a detailed description of the impact of cancer on the patient's life. These health tables, which illustrate the natural history of the disease, can also be used to assess new therapeutic regimens.

Adolescent↗
PubMed1975

Evaluation of mortality data for cervical cancer with special reference to mass screening programs, Denmark, 1961-1971.

During the years 1961-1971, a total of 3696 women died in Denmark from cervical cancer. The annual mortality per 1000 was 0.23 and was constant in this period. The mortality was 0.30 in the Capital where a mass screening program has existed since 1968; in the Provinces, where screening was negligible, the rate was 0.21; the time trend was also constant. The mortality was low in youth, reaching a level of 0.30 around 45 years. Single women had the lowest mortality; among married women it was double, among widows 2-4 times higher, among divorcees 4 times. Within the marital groups, the Capital had higher or the same rates as the Provinces, except for divorcees in the Provinces who had higher rates. The lowest socioeconomic groups had the highest death rates at young ages. The effects of a total vs. an age-specific case-finding program have been estimated under three circumstances, namely that mass screening could reduce the cervical cancer mortality by 10%, by 50%, or by 100%. The impact on the public's health has been evaluated by relating the hypothetically prevented cervical cancer deaths to all cancer deaths and to deaths from all causes. The general population was subdivided by age, marital status and residence and ranked according to cervical cancer mortality. These data were used to design programs which would minimize the number of examinees and maximize the number of prvented deaths.

Adult↗
PubMed1975

Medical observations and bias.

Many clinical and epidemiologic studies are based on different physicians' readings. A method to calibrate the various examinations is described. The standard reader's and others' results are plotted in a correlation diagram. Their readings are characterized by three parameters: frequency of agreement, average difference in size, and variance. In each study, the acceptable range of deviation from the standard reader should be decided. The standard reader is characterized by two requirements: a) that he is consistent, i.e., that a second reading shows a high rate of agreement, a small difference and a small variance between the two readings, and b) that he is reproducible, i.e., that other experienced doctors accept his classification and arrive at the same result. When statistical tests are used, it is understood that systematic errors are not present in the basic data. If this is not the case, the validity of the statistical tests is lost and results distorted or even meaningless. The second part of the study discusses types of bias encountered in epidemiologic studies and gives examples showing that the quantitative significance of bias can be considerable.

Analysis of Variance↗