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Biomedical subjects

J M Harper

Publications and source records attributed to J M Harper.

71 records · Page 4Linked to original sources
PubMed1968

Association of C-reactive protein and circulating leukocytes with resistance to Staphylococcus aureus infection in endotoxin-treated mice and rabbits.

The response of rabbits and mice to treatment with Escherichia coli endotoxin, as measured by C-reactive protein (CRP) and leukocyte levels, and resistance to Staphylococcus aureus infection was studied to evaluate the significance of these responses and their associations. In both species, there was an initial leukopenia without early recovery of normal lymphocyte levels. This was followed by an increase in polymorphonuclear leukocytes and a return to near the normal range. The CRP level was slightly altered during the stage of decreased resistance and increased throughout the remainder of the period of observation. The resistance level was decreased initially, recovered to normal levels, and continued to increase. The changes in CRP and resistance levels were closely associated. It would appear that this association between CRP and resistance, the antibacterial activity of CRP, and its action on the polysaccharides obtained from bacterial cell walls are evidence for the participation of CRP in nonspecific resistance to infection.

Animals↗
PubMedDate not supplied

Progression of left main coronary artery stenosis following left anterior descending coronary artery angioplasty.

Although recent clinical experience indicates a high success rate, percutaneous transluminal coronary angioplasty (PTCA) is still associated with serious complications which usually occur during or shortly after the procedure and are principally related to the lesion or segment of vessel being dilated. We report 2 cases of subacute progression within months of left main stenosis following successful, uncomplicated left anterior descending (LAD) coronary PTCA. Identification of left main trunk involvement may mandate earlier follow-up or intervention.

Adult↗
PubMedDate not supplied

Freezing red blood cells prepared for quality control of antiglobulin sera.

A small-aliquot freezing technique was employed to store at -80 C red blood cells (RBC) prepared for quality control of antiglobulin sera. These RBC were used to test the specificity and potency of both polyspecific and monospecific antiglobulin sera on the day of use. Following deglycerolization, about 83 per cent of test RBC were recovered. They were then stored as 5 per cent suspensions in 0.9% NaCl at 4 C for up to two weeks and tested for specific agglutination. EIg (RBC sensitized with immunoglobulins) and EC4 (RBC sensitized with the fourth component of human complement) remained reactive for the two-week period. EC43 (RBC sensitized with both the fourth and third components of human complement) tended to lose reactivity only with anti-C3c antibodies following deglycerolization and storage. EC3d (RBC sensitized with the C3d fragment of the third component of human complement), produced in vivo as a result of Mycoplasma pneumoniae infection, remained reactive for the two-week period, whereas EC3d prepared by the alternative pathway of complement activation was useful only for one week. Use of deglycerolized test RBC improved quality-control procedures by saving materials and technician time as well as by providing a constant supply of uniformly prepared test RBC.

Complement C3↗
PubMedDate not supplied

Fecal glucocorticoids: a noninvasive method of measuring adrenal activity in wild and captive rodents.

To determine the utility of fecal corticosteroid concentration as a measure of chronic stress under laboratory and field conditions, we biochemically and physiologically validated a radioimmunoassay for corticosteroids in three rodent species, house mice (Mus musculus), deer mice (Peromyscus maniculatus), and red-back voles (Clethrionomys gapperi). The biochemical validations demonstrated that the assay accurately and precisely measured corticosteroid concentration in the feces. The physiological validation indicated that the assay was sensitive enough to detect the stress associated with (a) brief handling and bleeding of animals, (b) chronic caloric restriction, (c) exposure to a novel environment, and (d) exposure to a novel cold environment. Our results suggest that fecal measurements reflect stress levels experienced by these animals approximately 6-12 h before defecation. Therefore, given a judicious trapping and trap-monitoring protocol, this assay has considerable utility for measuring the stress levels at which animals actually exist in the field.

Adrenal Cortex Hormones↗
PubMedDate not supplied

Analysis of physical parameters associated with the measurement of high-energy x-ray penumbra.

The effect of dosemeter type and configuration on the measured penumbral distribution for Co-60, 6-MV, and 31-MV x rays has been determined in air using equilibrium buildup caps for three commercial detection systems including a silicon diode and two ionization chambers. The diode is shown to be measuring a different parameter in the penumbral region than the ionization chambers. This fact in combination with the lateral spread of the secondary electrons and the difference in the inside diameters of the ionization chambers results in significant differences between the measured beam penumbra. The latter effect is studied in more detail with a series of specially designed ionization chambers of varying inside diameter from 0.3 to 1.4 cm. A theoretical model is described which resolves these differences, indicates a method to determine the true penumbral primary-dose distribution and introduces the concept of an effective diameter for the ionometric measurement of high-energy x-ray penumbra. Recommendations are made concerning the dosemeters of choice for penumbral measurements over this range of photon energies.

Cobalt Radioisotopes↗
PubMedDate not supplied

Oral contraceptives and life expectancy.

Life expectancy for women in the United States is 77.34 years; women who take oral contraceptives (OCs) for five years before the age of 30 can expect to live about four days longer. This is due primarily to protection against ovarian and endometrial cancers. For women taking pills for five years in their thirties there is a maximum loss of 18 days on the average that is attributable to OC use, and for women over 45 this rises to 80 days. The decreased life expectancy is due mainly to the increased mortality from myocardial infarction and stroke. This is substantially less than life lost due to use of a variety of other substances, most notably tobacco.

Adolescent↗
PubMedDate not supplied

Questionnaire assessment of intake of specific carotenoids.

We determined whether estimation of intake of specific carotenoids with a standard food-frequency questionnaire (FFQ) could be improved by collection of additional data on the intake of carotenoid-rich food items. The foods included on an addendum to the standard FFQ were potentially important dietary contributors of alpha- and beta-carotene, beta-cryptoxanthin, lutein, zeaxanthin, or lycopene. Participants (n = 215), ages 50-74 years, provided fasting blood samples and completed the FFQ and the addendum. The participants were enrolled in a prepaid health plan and had undergone screening sigmoidoscopy for detection of colorectal polyps. Addendum foods were identified that accounted for variation in blood levels of specific carotenoids, conditional on intake of foods on the standard FFQ. Estimated carotenoid intakes from the standard FFQ, and from the modified FFQ with the selected addendum foods, were examined in relation to plasma carotenoid levels. The correlation coefficient between estimated carotenoid intake and plasma levels (adjusted for age, sex, serum cholesterol, alcohol intake, smoking status, and energy intake) were essentially the same for the standard and modified FFQs. The adjusted correlations for the standard FFQ only were 0.26 for alpha-carotene, 0.22 for beta-carotene, 0.36 for beta-cryptoxanthin, 0.32 for lutein+zeaxanthin, and 0.34 for lycopene. Adding carotenoid-rich foods to the FFQ did not improve estimation of intake for the carotenoids examined in this population. We conclude that assessment of intake of specific carotenoids with the FFQs currently in use may not necessarily be improved by a modified list of carotenoid-rich foods.

Adenomatous Polyps↗
PubMedDate not supplied

Erythrocyte folate levels, oral contraceptive use and abnormal cervical cytology.

The initial hypothesis of this study was that folate depletion is a risk factor for human papillomavirus infection and cervical epithelial cell abnormalities, including dysplasia. The prevalences of low erythrocyte folate levels (defined as < 140 ng/mL erythrocytes and determined by the growth of Lactobacillus) were measured in 250 University of California at Los Angeles students. Among oral contraceptive users, low erythrocyte folate was a risk factor for an abnormal cytologic smear in both benign atypia and squamous intraepithelial lesions. Odds ratios were statistically significant for biopsied women who did not have condyloma and for those who did not have squamous intraepithelial lesions but not for those with histologically confirmed intraepithelial lesions. Low erythrocyte folate was a risk factor for a positive Virapap result in oral contraceptive users. If the folate effects are causal, the findings suggest that erythrocyte folate levels should be higher in oral contraceptive users than in nonusers to protect against an abnormal cytologic smear.

Adult↗