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Biomedical subjects

F D Dallenbach

Publications and source records attributed to F D Dallenbach.

At least 19 recordsLinked to original sources
PubMed1989

[Disseminated peritoneal leiomyomatosis. A rare disease picture].

After taking oral contraceptive hormones continuously for 17 years, a 44 year old patient developed enlarging uterine leiomyomas and multiple small to tiny subperitoneal nodules throughout the pelvic peritoneum. Histologically and immunohistochemically, the nodules proved to be leiomyomas. Similar nodules were induced in young female guinea pigs by injecting them with estradiol twice weekly. The first nodules appeared after four months. Approximately 50 cases of Leiomyomatosis peritonealis disseminata (LPD) have been reported to date in the world literature. Of these, 23 patients were pregnant. Seventeen had taken oral contraceptives continuously for many years (from 8-17). The developing leiomyomatous nodules probably arise from the Müllerian epithelium, which is distributed throughout the subperitoneal mesenchyme. By appropriate individual predisposition and excessive hormonal stimulation, the Müllerian derivatives proliferate along lines of myofibrous differentiation. Since the oral contraceptives all contained in addition to estradiol the synthetic gestagen norethindrone (or lynestrenol) and since these same hormones led to identical tumor nodules in animal experiments, it seems to suggest, that the stimulation of the Müllerian epithelium results from a specific combination of hormones. A similar combination of hormones may develop endogenously during a hormonally disturbed pregnancy. To prove these assumptions, larger case and interdisciplinary studies are needed. It is of clinical importance to realize, that the dormant Müllerian epithelium may be stimulated by excessive hormones to proliferate and that the proliferations produced, such as the benign nodular tumors of LPD, must be differentiated from nodular metastases of malignant tumors.

Adult↗
PubMed1981

Intraglomerular microcirculation: measurements of single glomerular loop flow in rats.

With the use of a new fluorescent microscopic technique, we were able to measure the mean intracapillary velocities and pressures of single capillary loops of renal glomeruli of living rats. The technique involved photographing and recording the flow of fluorescent latex particles through the glomerular loops with a television monitor. In 25 rats the single glomerular loop flow velocity was 781 +/- (SD) 271 micrometers . sec-1. The mean diameter of the capillary loops measured 8.4 +/- 1.4 micrometers; their lengths were 72.3 +/- 37.5 micrometers. From the decrease in velocity of flow along the capillary loop, we were able to evaluate the filtration equivalent for the capillary surface. It was possible to measure intracapillary pressures of single glomerular loops continuously under microscopic control. High intracapillary pressures correlated with high intracapillary velocities. From the data we obtained, we were unable to calculate a filtration equilibrium at the ends of the observed capillary loops. For further correlations, we injected the glomeruli we had studied in the living state and examined them with the scanning electron microscope.

Animals↗
PubMed1979

[Microscopic, micro-chemical and fluorescent optical findings in endometrium with a copper-T intrauterine device in situ (author's transl)].

The uteri of ten patients who wore a copper-T for several months up to two years were examined immediately following hysterectomy by conventional microscopic techniques, fluorescent optical techniques after Acridin-Orange-Fluorochromization and by histo-chemical techniques for copper. With none of these methods changes in the endometrium could be found which explained the effect of the copper-T to inhibit implantation. Since practically any morphological change from the normal was absent it is suggested that the inhibiting effect on pregnancy of the copper intra-uterine devices is due to biochemical changes of the intra-uterine environment.

Adult↗
PubMed1979

Acute renal failure in Tupaia belangeri and rats.

Acute renal failure in man can best be simulated in model experiments by using either temporary occlusion of the renal artery or perfusions of noradrenaline into the renal artery. The kidney of the Tupaia belangeri, a primitive primate, is more resistant to temporary occlusion of the renal artery than of the rat. In Tupaia as in rats, anuria developing 48 hours after temporary ischemia is brought about by intratubular proteinaceous casts blocking the flow of urinary filtrate, most likely at Henle's loop. As proof that the proteinaceous casts block the tubular lumina, we found that when two micropipettes are inserted into the same nephron and that nephron perfused, the intratubular pressures rise, approaching systolic pressures.

Acute Kidney Injury↗
PubMed1975

[Etiology and epidemiology of breast carcinoma].

Statistics indicate that the cure-rate for breast cancer has improved little over the last 35 years. That fact and the gradual increase in incidence of mammary cancer among women of the Western World serve to stimulate investigations to learn how and why mammary cancer develops. To examine the problem from a new perspective, we review the prevalence of mammary cancer reported in domesticated and zoo animals. The disease proves to be exeptionally rare in all mammals except: 1) cats and dogs, which live among humans, and 2) certain strains of laboratory mice and rats. Since the mammary tumors of these animals are sensitive to certain hormones, drugs, dietary changes etc., they serve as ideal models for studying the etiology of the disease. Because hormones promote growth and development of the mammary gland they are especially important in the pathogenesis of breast cancer. Studies of viral etiology of mammary cancer in animals are compared with those reported in humans. From the fact that a completed first pregnancy at the age of 18 protects a woman against developing a mammary cancer later in life, but a first pregnancy at about 30 years does not, some investigators believe that high levels of estriol during pregnancy act to protect the breast. From our review of breast cancer we postulat" instead that it is the apocrine function of the breast itself that affords the protection of early birth. Carcinogenic substances taken up by the estrogen-sensitized developing epithelium are discharged with the colostrum before they can transform cells. When the first birth occurs however at age 30 the carcinogens absorbed and stored in the estrogenized epithelium from puberty on have many years for transforming the cells. Dogs and cats exposed to the same polluted world as man develop mammary cancers more commonly when they first bear young late in life. Those receiving antifertility agents develop more breast cancers than those which bear first when young. Cows develop no mammary cancers because they lactate so much. High doses of carcinogens readily induce mammary tumors in some rat strains, more readily when given after a pregnancy than before. Oriental women who move to America and change their living and dietary habits develop more often mammary cancer than those who stay in their home country.

Adolescent↗