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Biomedical subjects

K A Hansen

Publications and source records attributed to K A Hansen.

29 records · Page 2Linked to original sources
PubMed1992

Natural killer cell activity from pregnant subjects is modulated by RU 486.

Natural killer cells form an integral component of the body's innate immune system. Natural killer cell activity is reduced during pregnancy, especially in the latter half. To investigate the role progesterone may play in immunomodulating natural killer cell activity during pregnancy, we evaluated the effect of RU 486 on natural killer cells isolated from pregnant subjects. Natural killer cell activity was measured with an 18-hour, Chromium 51 release, microcytotoxicity assay with K-562 cells as target cells. We demonstrated that RU 486, in a concentration range from 5 to 40 mumol/L, augmented natural killer activity threefold to fivefold over baseline. This augmentation of activity was suppressed to baseline by the addition of excess progesterone. The addition of hydrocortisone resulted in an insignificant reduction in this augmented activity. This study suggests that progesterone may play a role as an immunomodulating factor in maternal acceptance of the fetal allograft.

Adolescent↗
PubMed1992

Changes in T-cell regulation of responses to self antigens in women with pelvic endometriosis.

OBJECTIVE: To study autoimmune aspects of endometriosis. DESIGN: Lymphoblast transformation and hemolytic plaque formation were used to assess specific T- and B-cell activity against endometrial antigens. SETTING: Military teaching hospital. PATIENTS: Ninety-four healthy women of reproductive age undergoing diagnostic laparoscopy as part of an evaluation for infertility or chronic pelvalgia were accordingly grouped into those with normal pelvic peritoneum (20), mild endometriosis (50), and severe endometriosis (24). MAIN OUTCOME MEASURE: The study assessed the proliferative and humoral responses of lymphocytes from women with and without endometriosis to endometrial antigens and quantified the number of B-cell precursors, T-helper cells, and T-suppressor cells to these antigens. RESULTS: Unfractionated endometrial antigens were similarly blastogenic for lymphocytes from women with and without endometriosis. Despite equivalent numbers of B-cell precursors to these antigens, antiendometrial antibody responsiveness appears to have increased in women with mild endometriosis because of a decrease in T-suppressor cell activity and declined in women with severe endometriosis because of a further drop in T-suppressor cell activity and an increase in T-helper cell activity, as compared with women without endometriosis. CONCLUSIONS: Taken together, these experiments support the possibility that pelvic endometriosis may result from a break in specific T-cell tolerance rather than nonspecific polyclonal activation of responder lymphocytes.

Autoantibodies↗
PubMed1992

Short term treatment with leuprolide acetate is a successful adjunct to surgical therapy of leiomyomas of the uterus.

Gonadotropin releasing hormone analogs (GnRHa) have been used to induce a reduction in the size of leiomyomas of the uterus after three to six months of therapy. However, none of the studies have noted a significant decrease in size by the first month. Additionally, the results of two reports have suggested long term therapy with GnRHa induced significant aberrations of serum lipoproteins. To evaluate whether or not analog treatment for a short course (two months) would be efficacious, 27 patients with leiomyomas documented by examination of the pelvic area and vaginal ultrasound, who desired to preserve reproductive potential, had myomectomies two and one-half months after commencing depot leuprolide acetate therapy. The reduction in size of the uterus was 35 percent by the first month and the average reduction in the total volume was 44 percent after two months of treatment (474 +/- 364 to 265 +/- 173 milliliters; p less than 0.01). Furthermore, the size of the uterus, determined by examination, decreased significantly from 13.6 +/- 4.0 weeks initially to 10.1 +/- 3.0 weeks preoperatively (p less than 0.0001). Estradiol levels became menopausal by one month of therapy and remained suppressed preoperatively. Menopausal symptoms were well tolerated. Cholesterol, high density lipoprotein, extremely low density lipoprotein and triglyceride levels were not altered by analog treatment, although low density lipoprotein increased from 117 to 130 milligrams per deciliter. A short course of depot leuprolide acetate reduced the size of leiomyomas and surgical tissue planes were preserved, facilitating removal of leiomyomas, and furthermore, there was no significant clinical alteration in lipoprotein or triglyceride levels.

Adult↗
PubMed1991

Antisperm antibodies to sperm surface antigens in women with genital tract infection.

Antisperm antibodies to sperm surface antigens in nulligravid women with primary upper genital tract infections were measured by the sperm mixed agglutination reaction assay. As many as 56% of women with a primary episode of pelvic inflammatory disease had antisperm antibodies. In addition, 69% of those women with no history of genital tract infection but with laparoscopic evidence of past pelvic infection had significant levels of circulating antisperm antibodies. Electroimmunoblots of sperm preparations probed with the sera of women who had either known or presumed upper genital tract infection revealed a uniformly recognized 69 kd antigen. In contrast, women with circulating antisperm antibodies before primary upper genital tract infection recognized up to five distinct sperm antigen determinants of 27, 54, 131, 146, and 174 kd. It is a distinct possibility that genital tract infections may lead to immunopotentiation of antisperm antibodies that could affect fertility.

Adolescent↗
PubMed1989

Calcium-activated potassium channels in human platelets.

The cationic fluorescent probe, DiSC3(5) was used to measure the membrane potential in human platelets. Hyperpolarization was induced by the addition of Ca2+ to the medium and also by the addition of the Ca2+ ionophore, A23187. In the absence of extracellular Ca2+ ([Ca2+]o) there was no response to A23187. The threshold concentration for [Ca2+]o was 20 microM and for A23187 was 12 nM. The increase polarity induced by [Ca2+]o was not affected by various K+ channel blockers. However, the effect of A23187 was inhibited by quinine and charybdotoxin, while apamin, tetraethylammonium, and the calmodulin inhibitors trifluoperazine and compound R24571 were ineffective. The resting membrane potential was -66 +/- 0.9 mV and was decreased by quinine. There are three conclusions from this study: (i) Ca2+-activated K+ channels exist in human platelets; (ii) they are the type that are apamin insensitive, charybdotoxin sensitive; and (iii) they may contribute to the resting membrane potential.

Adult↗
PubMed1983

Changes in 25-hydroxyvitamin D3 alpha- and 24-hydroxylase activities of kidney cells isolated from rats with either unilateral kidney damage or acute renal insufficiency.

25-Hydroxyvitamin D3 1 alpha- and 24-hydroxylase, NADPH-cytochrome c reductase, heme oxygenase, and ATPase activities were studied in viable kidney cells isolated from rats submitted to unilateral kidney damage (cortical electrocoagulation) and during the development of acute renal failure subsequent to excision of the contralateral undamaged kidney. Measurements of blood pH, plasma total and ionized calcium, phosphorus, creatinine, kidney histology, and phosphorus nuclear magnetic resonance spectroscopy determinations of phosphorus-containing compounds in kidney tissue were also performed. Seventy-two hours after unilateral kidney damage, no significant changes were observed in blood pH or in the plasma parameters studied. During this period, a significant increase in the activity of the 25-hydroxyvitamin D3 hydroxylases could be demonstrated in the cells of the contralateral undamaged kidney. A similar pattern of compensatory rise in the activity of the other enzymes studied was not detected. However, in the damaged kidney viable cells, the hydroxylase activities remained unchanged relative to those in sham-operated controls, despite a 5-fold increase in the inorganic phosphate content and a marked decrease in the organophosphorus and ATP content of this tissue. During the development of acute renal failure, a significant decrease in the activity of the hydroxylases occurred only when the rise in plasma creatinine concentration suggested severe renal insufficiency.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed1975

Trends in return migration to the South.

The rate of return migration to the South rose by nearly 19 percent between the late 1950's and the late 1960's and was an important factor in changing the South's overall migration pattern. But an increase in the rate of return migration was somewhat less important in changing Southern migration than (1) a decline in the rate of out-migration of native Southerners and (2) an increase in the rate at which non-Southern-born persons move to the South. The probability of former migrants returning to the South was over four times greater for whites than for blacks in the 1955-1960 period and three and one-fourth times greater in the 1965-1970 period. Since 1970 the rate of return migration has apparently continued to rise at a faster rate for blacks, but the black rate of return migration is still below the white rate.

Adolescent↗
PubMedDate not supplied

Teledyne Sleep Sentry: evaluation in pediatric patients for detection of nocturnal hypoglycemia.

Twenty-four insulin-dependent diabetic pediatric subjects were studied for 1444 nights for detection of nocturnal hypoglycemia with the Teledyne Sleep Sentry (Teledyne Avionics, Charlottesville, Virginia): a wristwatch-like unit that measures absolute changes in skin temperature and decreases in galvanic skin resistance, indicators of hypoglycemia. The device detected 42 of 46 recognized hypoglycemic episodes. One hundred fifty alarms were sounded without evidence of hypoglycemia, probably due to night sweating. Twenty-five percent of the subjects experienced unacceptable cutaneous reactions, presumably due to metallic iontophoresis.

Adolescent↗