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Biomedical subjects

M Steiner

Publications and source records attributed to M Steiner.

At least 253 records · Page 14Linked to original sources
PubMed1990

Influence of angiotensin converting enzyme inhibitor (captopril) on kidney epithelial cells in vitro: studies on potassium (86Rb) influx and cellular proliferation.

The effects of captopril on potassium influx and cellular proliferation in a dog kidney epithelial cell line (Madin-Darby canine kidney cells, MDCK) were studied. Na+K(+)-ATPase activity and the loop diuretic sensitive Na/K/2Cl- cotransport were measured using 86Rb as tracer substance. Cells were incubated with various concentrations of captopril (1-10 mmol/l). The furosemide sensitive Na/K/2Cl- cotransport was significantly decreased from 1 mmol/l onwards. Na+/K(+)-ATPase activity was lowered only when high amounts (10 mmol/l) of the drug were used. Cell proliferation was measured via [3H]thymidine incorporation. After incubation with 1 mmol/l captopril proliferation was strongly decreased (greater than 50%). Higher amounts (5-10 mmol/l) did not further suppress cell proliferation. The data suggest that natriuresis following ACE inhibition in vivo does not involve a direct effect of captopril on Na+K(+)-ATPase. However, the effect on cell proliferation may be of clinical relevance in respect to a possible mitogenic effect of angiotensin II.

Animals↗
PubMed1990

Nocturnal melatonin and cortisol secretion in newly admitted psychiatric inpatients. Implications for affective disorders.

Melatonin secretion has been suggested as a marker of both circadian and noradrenergic dysfunction in affective disorders. Seventy-two newly admitted psychiatric inpatients [49 with major depressive disorder (MDD), 12 with schizophrenia, and 11 with intermittent depressive disorder (IDD)] underwent neuroendocrine screening at 0200, 0800, 1600 and 2300 hours prior to and the day following dexamethasone administration. All groups showed a drop in cortisol following dexamethasone. Dexamethasone nonsuppression was found in 20 of 49 patients with MDD, in none of the schizophrenics and in none of those with intermittent depressive disorder. Mean melatonin levels decreased significantly after the administration of dexamethasone across all four groups. Overall, the schizophrenic group had a significantly greater mean melatonin level than each of the other three groups, whereas the three depressive groups did not differ significantly from one another. Only at 2300 hours did both the schizophrenic group and the MDD patients with normal dexamethasone suppression show significantly greater melatonin levels than the MDD patients with dexamethasone nonsuppression or the IDD group. The observed trend for a low circadian melatonin profile in IDD patients with superimposed personality disorders is puzzling.

Adult↗
PubMed1990

Studies on leukocyte beta-adrenergic receptors in depression: a critical appraisal.

Alterations in beta-adrenergic receptors (BAR) of human mononuclear leukocytes (MNL) are considered to reflect changes in central noradrenergic function and have been studied in a number of diseases. This paper critically reviews the results of recent studies on MNL-BAR in depression, with particular emphasis on the biochemical and clinical methodologies used. Despite considerable differences in these methods, a number of laboratories report consistent decreases in MNL-BAR density and significantly reduced functional response in patients as compared to controls. These studies used MNL, isolated from patients who had a greater than 14 day drug washout, and BAR-densities were measured in membrane preparations, using full Scatchard analyses, and 125I-ICYP or 3H-DHA as the ligand. Functional response of MNL-BARs was assessed by the determination of isoproterenol-stimulated cyclic AMP accumulation. A comparison of methods used by these groups further indicates that additional biochemical parameters such as lymphocyte preparation and standardized experimental conditions for the binding assays are also important for obtaining consistent results. The clinical methods in rigorous study designs also include clearly stated inclusion/exclusion criteria for patients, and age-, and gender-matched patient-control populations. Whether the reduced MNL-BAR density and function is an inherited abnormality in depressed patients, or results from downregulation by elevated catecholamines is at present not known. Studies are needed to characterize further the changes in MNL-BARs in depression and to evaluate the effects of caetcholamines and hormones on this system. Based on critical assessment of the methods reviewed we propose specific biochemical and clinical guidelines, and recommend, that these be followed in future studies on MNL-BARs in this disease.

Cell Count↗
PubMed1990

Cerebral correlates of imagining colours, faces and a map--II. Negative cortical DC potentials.

Cortical activation patterns as measured by negative shifts of the scalp-recorded cortical steady potential ("DC shifts") were assessed in 28 normal subjects during imagining colours, faces, and a spatial map. Imaging resulted in sustained negative DC shifts at temporal, parietal and particularly at occipital sites. The topographic distributions of such DC shifts was modulated as a function of whether spatial or visual imagery was performed. During imaging the spatial map, a parietal maximum was observed, as opposed to a distribution in favour of temporal and occipital sites during imagining faces and colours. Results suggest a neuroanatomical dissociation between visual and spatial imagery. Since a similar visual-spatial dichotomy exists in perception, the finding is interpreted as further evidence of a shared cerebral substrate for images and percepts. The results are discussed in conjunction with the joint blood flow study.

Adult↗
PubMed1990

Karyotype evolution in a simian virus 40-transformed tumorigenic human cell line.

Normal human foreskin fibroblasts (HSF4) were transfected using the pSV3-neo plasmid. A pool of 10 G418-resistant colonies, HSF4-T12, showed a progressive increase in the expression of a number of in vitro transformation markers with passage in culture and became immortalized. Although no tumors were formed when cells were injected subcutaneously into nude mice, this cell line produced progressive tumors when cells were injected into preimplanted Gelfoam sponges in the mice. When these tumors were cultured in vitro and subsequently injected subcutaneously, progressive tumors were produced with median latency periods as short as 4 weeks. Three phases of cytogenetic change could be distinguished. At early passages after transfection. HSF4-T12 exhibited many random chromosomal changes. At a time just after immortalization, both flow karyotype and G-banded analyses showed the appearance of balanced clonal rearrangements. These included t(2;4), t(2;14), t(3;?), 6p-, i(6p), 8p-, t(14;15), i(15), and t(18;?). These clonal rearrangements were stable with passage in culture, and less variability from cell to cell was noted. The only consistent chromosomal loss observed was -Y. Analysis of three independent tumors showed characteristic loss of chromosomal material rather than balanced chromosomal rearrangements. Frequent loss of 6q and chromosomes #13, 15, 20, and Y was noted.

Animals↗
PubMed1990

CA-15.3, TPA and MCA as markers for breast cancer.

Serum concentrations of CA-15.3, tissue polypeptide antigen (TPA) and mucinous-like carcinoma-associated antigen (MCA) were measured in 327 women: 81 controls, 93 patients with benign breast disease, 46 patients recently diagnosed with breast cancer and 107 patients during breast cancer follow-up. CA-15.3 was elevated in 16% of the controls, in 29% of the patients with benign breast disease, in 65% of the breast cancer patients and in 74% of the follow-up patients. TPA was elevated in 4%, 11%, 36% and 75%, respectively. The corresponding figures for MCA were 10%, 8%, 30% and 64%. The highest sensitivity for cancer detection (74%) was obtained with a combination of CA-15.3 and TPA, while the specificity of this panel was 75%. The negative predictive value of these combined tests was 93%. MCA scored lower values, being only 30% sensitive. The CA-15.3/TPA panel may increase sensitivity compared with single marker tests and provide additional information for clinical evaluation.

Antigens, Neoplasm↗
PubMed1990

Leiomyoma of the kidney: presentation of 4 new cases and the role of computerized tomography.

Renal leiomyoma is a challenging diagnostic and therapeutic condition. It is clinically similar in presentation and radiographic appearance to its malignant counterpart, leiomyosarcoma. We review 30 cases of clinically diagnosed leiomyoma of the kidney from the literature, including 4 new cases with emphasis on the computerized tomography findings. Computerized tomography may locate a renal leiomyoma serendipitously in an asymptomatic patient. If the lesion is peripheral or in the parapelvic area and a plane can be seen between the tumor and kidney a capsular tumor, such as a leiomyoma of the kidney, might be considered in addition to the more common renal cell carcinoma. Renal leiomyomas have a variable radiographic pattern from that of a pure cystic to a mixed solid/cystic to an entirely solid lesion. Renal leiomyomas usually are sharply demarcated from the surroundings. Although computerized tomography cannot distinguish a renal leiomyoma from other benign or malignant renal processes the presence of invasion can virtually eliminate this benign tumor as a diagnosis. Since a preoperative diagnosis cannot be made, management involves renal exploration and radical nephrectomy in the larger lesions with a renal-sparing operation possible in selected cases. After treatment patients have a uniformly excellent prognosis.

Aged↗
PubMed1990

Erythropoietin has a mitogenic and positive chemotactic effect on endothelial cells.

Erythropoietin is known to be a hematopoietic growth factor with a singularly specific action on the proliferation and differentiation of erythroid progenitor cells. We have observed a dose-dependent proliferative action of human recombinant erythropoietin on human umbilical vein endothelial cells and bovine adrenal capillary endothelial cells. Binding studies with radioiodinated recombinant human erythropoietin revealed a large number (approximately 27,000) of an apparent single class of receptors with an affinity in the 10(-9) M range. Linkage of the radiolabeled ligand to its receptor via a bifunctional crosslinking agent allowed us to identify an endothelial cell protein of 45 kDa as the principal receptor associated with this mitogenic effect of erythropoietin. Recombinant human erythropoietin also enhanced the migration of endothelial cells.

Cell Division↗
PubMed1990

Effects of n-3 fatty acids in essential hypertension.

We examined the effects on blood pressure, plasma lipoproteins, and platelet function when marine oil supplements (rich in n-3 fatty acids) or vegetable oil supplements (rich in n-6 fatty acids) were added to the usual diets of patients with mild essential hypertension. In a randomized, double-blind, parallel-group study, patients received 50 g of either marine oil (n = 8) or vegetable oil (n = 8) daily for 6 weeks following a baseline observation period. Diastolic blood pressure declined during treatment with fish oil (mean +/- SEM, 96 +/- 2 v 89 +/- 2 mm Hg, P = .02), but did not change with vegetable oil (92 +/- 1 v 94 +/- 1 mm Hg). Systolic blood pressure did not change significantly during either treatment. Serum triglycerides declined (by approximately 30%) in patients receiving only marine oil, but total cholesterol, LDL-, HDL-, HDL2-, and HDL3-cholesterol-subfractions and apolipoproteins A-I and B were unchanged in both treatment groups. Bleeding time increased by 33% during treatment with marine oil but did not change with vegetable oil supplements. Marine oil did not alter in vitro platelet aggregation thresholds. The lack of a significant correlation between blood pressure changes and platelet membrane fluidity, plasma renin activity, aldosterone, norepinephrine, or epinephrine suggests that these variables did not mediate the antihypertensive effect of the marine oil. We conclude that large doses of marine oil reduce diastolic blood pressure, lower triglycerides, and increase bleeding time in patients with mild hypertension.

Adult↗
PubMed1990

The influence of temperature on somatosensory-evoked potentials during cardiopulmonary bypass.

Somatosensory-evoked potentials (SEPs) after median nerve stimulation were recorded in 10 neurologically normal patients during cardiopulmonary bypass and hypothermia. In all patients the changes of the latencies (spinal N13, cortical N20 and N35) and the central conduction time during cooling, and the decrease in latencies during rewarming was described by a gamma function. The analytic discussion of pooled data of all patients led to another SEP-latency-temperature relationship than the observation of each single patient. In 6 of 10 patients there was found a maximum of latency increase before the minimal temperature was reached. The cooling and the rewarming curve had to be considered separately. Latency changes of SEPs during hypothermia are discussed as a very complex phenomenon influenced by many technical and patient factors. This reduces the value of SEPs as an index of central nervous system integrity during open heart surgery and hypothermia.

Adult↗
PubMed1990

A contribution to classification of hallucinations.

Proceeding from the hypothesis that auditory hallucinations in psychotic patients have another biological basis than hallucinations provoked by hypnotic suggestion in healthy persons, we performed a symptom-comparative study by means of 99mTc-HMPAO single photon emission computed tomography. The results confirm the importance of pathogenesis in symptom-oriented psychiatric research.

Adult↗
PubMed1990

Postpartum psychiatric disorders.

The literature on postpartum psychiatric disorders (PPD) is reviewed with particular reference to recent advances in the field. Despite the prevailing tendency to consider PPD as a manifestation of other pre-existing psychiatric disorders (i.e. affective, schizophreniform, organic, neurotic, etc.) a growing number of studies point to the uniqueness and specificity of postpartum symptomatology. Theories of etiology, psychosocial as well as biological, are still wide-ranging and unconvicing. Attempts to predict PPD and/or to identify mothers-to-be at risk are based largely on retrospective studies or else are hindered by the use of nonspecific instruments. Society's implicit belief in the "joys of motherhood" may have further contributed to the obscurity surrounding these frequently occurring disorders. Interventions follow conventional methods of psycho- and pharmacotherapy but the multidisciplinary treatment approach especially for women with acute PPD who require hospital admission is gaining wider acceptance. The inpatient psychiatric mother-baby intensive care unit model is part of this approach.

Depressive Disorder↗
PubMed1990

Persistent cutaneous insulin allergy resulting from high-molecular-weight insulin aggregates.

Cutaneous insulin allergy remains a clinical problem despite the use of highly purified human insulins. We used in vitro lymphocyte-transformation studies to examine the reactivity of various insulin formulations in diabetic patients with (n = 4) and without (n = 8) cutaneous allergies. Nonspecific response to concanavalin A demonstrated a greater than 40-fold response in both groups. Control patients did not respond to the addition of commercial insulin preparations (stimulation index [SI] less than 4), whereas allergic patients had an 11-fold response to beef (P less than 0.01), a 10-fold response to pork (P less than 0.01), and a 6-fold response to human (P less than 0.01) insulins. This response was limited to a single insulin manufacturer's preparations and was uniform in all three species tested. Efforts to identify the offending agent revealed no lymphoblast transformation when crystalline insulin was used or when commercial preparations were purified to a single peak by high-performance liquid chromatography (HPLC). Pure crystalline insulin dimers of beef, pork, and human species were tested; control subjects responded with mean SIs of 1.9, 1.9, and 1.8, respectively, whereas allergic patients showed greater reactivity to beef (SI 7.3) and pork (SI 14.8). The lymphoblast-transformation response to crystalline human dimer was dose dependent with mean SIs of 0.9 at low concentration (2.8 ng/ml) and 19.2 at a higher concentration (20.4 ng/ml). The commercial insulin preparations were run on size-exclusion HPLC to determine high-molecular-weight aggregate content. Independent of species, a single manufacturer had products demonstrating aggregate levels 3- to 6-fold higher than those found in other manufacturers' preparations.(ABSTRACT TRUNCATED AT 250 WORDS)

Concanavalin A↗
PubMed1990

Electrical stimulation of bone and its implications for endosseous dental implantation.

Applied electrical potentials can alter cellular movement, stimulate production or destruction of cells, and change the chemical concentration and composition of both soft tissue and bone. These actions vary depending on the microamperage and duration of the applied current and whether it is continuous or pulsed, the type of metallic electrode, and the types of cells or tissues involved. Relative to skeletal effects, researchers have accumulated data from bone cell cultures, embryonic and adult animal bone, and human clinical studies. This article reviews the historical use of electric current for fracture healing, the piezoelectric effect found in tissues, and the possible deleterious effects of electrical stimulation. The types of electric current presently used for treating extremity fractures and reports where electric current has been used on tissues in the oral cavity are discussed. Alternate sources of energy to stimulate bone and possible implications for use of electrical stimulation to augment attachment of endosseous dental implants are also included.

Bone Regeneration↗
PubMed1990

SPECT quantitation of iodine-131 concentration in phantoms and human tumors.

The validity of SPECT measurement of iodine-131 (131I) concentration was tested in vitro in phantoms and in vivo by measuring bladder urine concentrations. Phantom studies comparing known and SPECT measured concentrations showed a good correlation for 131I (r = 0.98, s.e.e. = 20.94 counts/voxel) for phantoms of 25 to 127 cc and concentrations of 0.13 to 9.5 microCi/cc. The in vivo, in vitro correlation of 131I concentrations in the urine was also good (r = 0.98, s.e.e. = 0.677 microCi/cc). Quantitative SPECT was used to calculate the effective half-life and dosimetry of radioiodine in 12 sites of thyroid carcinoma in seven patients. SPECT was also used to determine the dosimetry of [131I]MIBG (metaiodobenzylguanidine) in two patients with carcinoid, two with neuroblastoma, and one with pheochromocytoma. The radiation dose for thyroid carcinoma metastases varied between 6.3 and 276.9 rad/mCi. The dose from MIBG varied between 13.4 and 57.8 rad/mCi. These results indicate the validity of quantitative SPECT for in vivo measurement of 131I and the need to measure the concentration of 131I in individual human tumor sites.

3-Iodobenzylguanidine↗