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Biomedical subjects

H Michael

Publications and source records attributed to H Michael.

50 records · Page 3Linked to original sources
PubMed1983

Colposcopic and pathologic features in two cases of DES-related vaginal clear-cell adenocarcinoma.

Two cases of vaginal clear-cell adenocarcinoma occurred as a result of maternal ingestion of diethylstilbestrol during pregnancy. The first case was diagnosed during the patient's first office visit. The second patient was first seen by the authors in 1976 and was followed at six-month intervals during the ensuing six years; the adenocarcinoma developed during this interval. Colposcopy and cytology were important in the diagnosis of both cases.

Adenocarcinoma↗
PubMed1982

Cell surface insertion of exogenous epidermal growth factor receptors into receptor- mutant cells: demonstration of insertion in the absence of added fusogenic agents.

We show that epidermal growth factor (EGF) receptor can be transferred in a biologically active orientation from donor hepatic membranes to recipient receptorless fibroblast cells. The recipient cells (NR-6) normally lack EGF receptors and are biologically unresponsive to EGF. The transfer of receptors from donor plasma membranes to recipient NR-6 surface membranes occurs in the absence of any added fusogenic agent. Studies on time and temperature dependence of this transfer indicate that it is due to preferential insertion of the EGF receptor over the other hepatic proteins. The inserted receptor is exceptionally stable to dissociation or damage, and this facilitated studies on its biological properties. The inserted receptor confers upon the hitherto unresponsive variant NR-6 cells a specific biological responsiveness to EGF as measured by EGF-induced stimulation of DNA replication and cell division. These findings suggest the existence of an affinity-mediated mechanism for the biologically active insertion of exogenous EGF receptors into receptorless variant cells. This insertion approach may be of use in the identification of receptor-associated membrane proteins that play a role in the transmission of EGF biological message.

Animals↗
PubMed1978

Principles of nephron differentiation.

UNLABELLED: Differentiation of cell function should be studied in homogeneous cell populations. The differentiating mammalian kidney is a thoroughly heterogeneous organ. Consequently, the single epithelial segment was studied in situ and, particularly, by in vitro analysis of physical, chemical, and ultrastructural phenomena in perfused and nonperfused dissected nephrons. RESULTS: The changes of hydraulic permeability in the proximal nephron appear to be important in utilizing extracellular forces for absorption, since cellular transport is restricted by low basolateral membrane area and by ion pump sites (Na+-K+-ATPase). Salt transport in the diluting segment, by contrast, changes at constant osmotic permeability and at increasing ion concentration gradients across the epithelium. Extracellular volume and osmotic homeostasis in the neonate testify to the competence of organ function, although cell structure and function differentiate. In the future, interactions between nephron cell functions will be studied by altering the natural sequence of phenomena during differentiation.

Animals↗
PubMed1975

Primary hypomagnesemia. I. Absorption Studies.

The clinical course of 2 patients with primary hypomagnesemia is reported. In one male patient, 5 months old, measurements of magnesium retention, intestinal absorption, fecal excretion and renal clearance were performed. The retention (2.8%) and absorption (7.8%) of 28-Mg were markedly reduced in comparsion to controls (average retention 25% and average absorption 28%). The retention values of the parents and other realtives did not differ from those of healthy adults. The examined patient was sucessfully treated with trimagnesium dicitrate containing 1.75 g magnesium per day.

Calcium↗
PubMed1975

Influence of catecholaminergic agents on narcotic binding in brain.

The effects of various agents on the specific tissue binding of 3H-naloxone and 3H-naltrexone were examined. In addition to the narcotics, alpha-adrenergic blockers and dopamine antagonists also significantly inhibited the specific bindings of these opiates. The binding of naloxone or naltrexone was not significantly altered by beta-adrenergic blockers, agents which block the effects of acetylcholine, serotonin and histamine at the receptor level, and a number of other drugs. Kinetic analyses revealed that the alpha-adrenergic and dopamine antagonists competitively inhibited the binding of naloxone. The results of these studies provide additional evidence for an interaction between the narcotics and catecholaminergic agents.

Animals↗
PubMedDate not supplied

The risk of nodal metastasis in early adenocarcinoma of the uterine cervix.

A functional and widely accepted definition of microinvasive cervical adenocarcinoma remains elusive. The purpose of this study was to determine at which depth of invasion the likelihood of lymph node metastasis or disease recurrence was so small that conservative surgery could be considered appropriate. Charts of patients with adenocarcinoma of the cervix (ACC) who underwent radical hysterectomy and pelvic lymphadenectomy (n = 98) at Indiana University Medical Center from 1987 to 1998 were retrospectively reviewed. Patients with stage IA1-IB1 lesions were included in the study. Patients treated with preoperative radiotherapy were excluded. Pathologic parameters evaluated included histologic type, depth of stromal invasion (DOI), and the presence of lymphatic vascular space invasion, or lymph node metastases. The patient median age was 39 years (20-65). The median time of follow-up was 30 months (4-124). Lymph node metastases were found in ten patients and 11 developed recurrences. The precise DOI could be measured in 84 patients. Of the 48 patients with cancers with a DOI </= 5 mm, none had involved parametria or nodes; whereas eight of the 36 with a DOI > 5 mm had nodal metastases (P = 0.00069). None of these 48 patients with a tumor DOI </= 5 mm developed a recurrence whereas six of the 36 patients with a tumor DOI > 5 mm developed recurrent disease (P = 0.0048). The risk of nodal metastases and recurrence is so low in patients with ACC and DOI </= 5 mm that for patients with such depth documented on conization with negative margins pelvic lymphadenectomy may be omitted.

Adenocarcinoma↗
PubMedDate not supplied

Determinants of measured dialysis venous pressure and its relationship to true intra-access venous pressure.

Venous pressure measured at the venous bubble trap (VPdm) is a complex function of true intra-access pressure (VP0), hematocrit, needle gauge, and blood flow. In a patient free circuit, needle gauge, hematocrit, and blood flow influenced the pressure drop through the venous return needle. Measured intra-access pressure (VPm) and VPdm also were determined 149 times in 83 subjects. The increase in VPdm above VP0 under conditions of flow through 16 gauge needles was affected by blood flow rate, hematocrit, and VP0 with coefficients similar to those found in vitro. Calculation of VP0 from VPdm produced an absolute difference greater than 20 mmHg in 35-40% of cases. Mean VP0 was significantly lower in subjects with native compared with expanded polytetrafluorethylene accesses. It was concluded that VP0 is influenced by access type and can be estimated but that direct measurement is preferred. Direct measurement of VP0 may be a sensitive test to screen for venous outlet stenosis because it should vary with access flow and outlet geometry.

Arteriovenous Shunt, Surgical↗
PubMedDate not supplied

Recombinant human erythropoietin does not increase clotting in vascular accesses.

The incidence of vascular access clotting was evaluated over 5.25 years. The first 32 months served as a control period. During the second period of 31 months, recombinant human erythropoietin (epoetin) was used for an average duration of 13 months (range, 2-32 months) in 79 patients. The overall incidence of vascular access clotting decreased from a monthly rate of 0.06 to 0.03 events per patient-month over the 5 year period. Distribution of the number of events per patient did not differ between the two periods, with 55% to 60% of patients having no clotting episode. Patients with recurrent clotting (two or more events) accounted for 68% of episodes. During the second period, there were no differences in the incidence of vascular access clotting in epoetin treated patients vs untreated patients (0.38 events per patient-year vs. 0.46 events per patient-year, both slightly lower than in period 1 [0.52 events per patient-year]). It is concluded that epoetin does not increase vascular access clotting.

Anemia↗