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Biomedical subjects

M Steiner

Publications and source records attributed to M Steiner.

At least 307 records · Page 17Linked to original sources
PubMed1988

Postrhinoplasty epistaxis. Role of vitamin E?

Postrhinoplasty epistaxis occurred in two patients, both of whom were found to be ingesting megadoses of vitamin E. The rate of vitamin E consumption in a population of 100 uncomplicated nasal operations during this same period was 16%. A review of the medical literature on vitamin E found recent evidence demonstrating a marked decrease in platelet adhesiveness with megadose ingestion of vitamin E. It is concluded that this should be avoided in the perioperative period.

Adult↗
PubMed1988

DC-potential shifts and regional cerebral blood flow reveal frontal cortex involvement in human visuomotor learning.

In the present study, two different physiological parameters were measured to describe brain activity related to visuomotor learning: performance-related DC-potential shifts and regional cerebral blood flow (rCBF) by Tc-99m HMPAO brain SPECT (Single Photon Emission Computerized Tomography). Visuomotor learning was required in a conflicting situation: a visual target moved on a screen and had to be tracked by moving the right hand in an inverted fashion (IT), e.g. movements of the target to the right side required hand movement to the left and vice versa. Compared to a normal, non-inverted control task (T), IT required the development of a novel motor program and the prevention of returning to routine direct pursuit. These additional demands in IT caused a relative hyperperfusion in regions including the middle frontal gyri, frontomedial cortex (including the supplementary motor area, SMA), right basal ganglia (caudate-putamen) and left cerebellum. Correlations of rCBF values between the middle frontal gyrus and basal ganglia may indicate a functional relation between these two brain structures. Visuomotor performance was accompanied by slow negative DC-potential shifts. In frontal and to a lesser degree in central recordings, amplitudes of DC-negativity were larger in IT than they were in T. This additional frontal negativity covaried with the success of learning. Results substantiate, now using a dual approach, previous suggestions that the frontal lobe plays an important role in visuomotor learning.

Adolescent↗
PubMed1988

Hexa-methyl-propylene-amine-oxime (HMPAO) single photon emission computed tomography (SPECT) in epilepsy.

Twenty-eight normal volunteers and 74 seizure patients were investigated with hexa-methyl-propylene-amine-oxime (HMPAO) brain single photon emission computed tomography (SPECT). Fifty-four patients suffered from partial seizures and 20 patients had generalized seizures. Indices describing regional tracer distribution (RIs) were calculated in all investigated subjects. Regions whose RI exceeded the mean normal RI +/- 3 SD were defined as abnormally perfused. In normals a significant interhemispheric asymmetry of HMPAO deposition was found, with higher RI values in the right frontal, parietal, temporal and occipital regions. In 59.3% of partial seizure patients abnormal RIs were found. Low RIs were detected predominantly in the frontal and temporal cortex, while elevated RIs were observed predominantly in the anterior basal ganglia. Only in 20% of the cases with generalized seizures, abnormal RIs were found. In one patient an ictal and 3 follow-up SPECT studies were obtained. Here SPECT results indicated transient rCBF changes between the ictal and seizure free state. EEG and SPECT foci were ipsilaterally located in 69.2% of the partial seizure cases. The results indicate that HMPAO brain SPECT is valuable for the detection of rCBF abnormalities in seizure patients and that patients with partial seizures have mostly several abnormally perfused areas in their brains.

Adult↗
PubMed1988

Short-term storage of freshly harvested bone.

An in vitro study was designed to test effects of various graft storage media on glucose metabolism and collagen synthesis of embryonic chick tibiae, using these variables as indices of bone cell viability. Normal saline solution, distilled water, and 5% dextrose in lactated Ringer's solution were evaluated after a 5-hour incubation and again after a 3-day recovery period in a complete culture medium. The study suggests that bone grafts may be stored in normal saline solution or 5% dextrose in lactated Ringer's solution for up to 5 hours. Normal saline solution is recommended because of fewer deleterious effects. Distilled water should not be used as a storage medium for bone grafts.

Animals↗
PubMed1988

Whole abdominal irradiation following chemotherapy in advanced ovarian carcinoma.

One hundred and sixteen patients with advanced ovarian carcinoma, who underwent primary cytoreductive surgery, received 6-11 courses of chemotherapy by cis-platin (50 mg/m2) and adriamycin (50 mg/m2) every 21 days. This was followed by second look laparotomy in 66 patients with no clinical evidence of disease. Consolidation abdominal irradiation was administered to 43 patients. Two techniques of irradiation were employed: between 1980-1983 whole abdominal irradiation was used and patients were to receive 3000 cGy in 4 weeks (Schedule I). Due to myelosuppression only 13 of 26 patients (50%) completed the planned dose of radiation. Between 1983-1985 the target volume was divided into upper and lower parts. First, the lower abdomen received 3000 cGy in 3 weeks, and then the upper abdomen received the same dose (Schedule II). Sixteen of seventeen patients (94%) thus treated, completed the planned dose of radiation. The actuarial survival for all 116 patients was 28% of 5 years. Irradiated patients with negative second look laparotomy had a survival probability of 100% at 24 months. Irradiated patients with microscopic disease at second look operation had an actuarial 5-year survival of 66%. Patients with minimal residual disease at second look laparotomy, receiving consolidation abdominal irradiation, had an actuarial survival of 5% only at 36 months. It is concluded that consolidation radiotherapy is effective in patients with negative or microscopic residual disease at second-look laparotomy. In regard to bone marrow tolerance, split field technique of irradiation is preferred.

Abdomen↗
PubMed1988

Clinical manifestations of choanal atresia in infancy.

The clinical features of 41 infants with various types of nasal obstruction were reviewed to study the correlation between the degree of nasal obstruction and clinical manifestations. Twenty-one subjects had bilateral choanal atresia/stenosis; 12 had unilateral choanal atresia/stenosis, and eight who were referred with suspected choanal atresia had a simple inflammatory nasal obstruction. Patients with bilateral choanal obstruction and patients with unilateral choanal obstruction or rhinitis showed no differences in clinical picture or in referral age. Many infants with either unilateral or bilateral choanal obstruction had one or more symptoms not fully relieved after surgical repair, although the choanae were widely patent. At long-term follow-up the surviving patients showed spontaneous recovery and good nasal respiration. Overall, five patients died. Since the common syndrome appeared to be related to a dysfunction of the autonomic nervous system, we conclude that any type of nasal obstruction may exacerbate or precipitate an underlying maturational autonomic disturbance.

Aging↗
PubMed1988

Role of endogenous prostacyclin in myocardial blood flow regulation distal to a severe coronary stenosis.

To test the hypothesis that endogenous prostacyclin is required to maintain reduced arteriolar tone distal to a severe coronary arterial stenosis under basal conditions and during challenge with a vasoconstrictor eicosanoid such as thromboxane A2 10 closed chest, domestic swine were prepared with an artificial stenosis, which reduced the luminal diameter of the left anterior descending coronary artery by 80%. Haemodynamic variables, regional myocardial blood flow (microsphere method), and lactate metabolism were measured at control (1); after infusion of U46619 (thromboxane A2 mimetic) distal to the stenosis at 1 microgram.min-1 for 10 min and 5 micrograms.min-1 for 10 min; at control (2); after indomethacin infusion distal to the stenosis; and after repeat infusion of U46619. At the end of the study the animal hearts were removed and their coronary vessels harvested for in vitro determination of prostacyclin (PGI2) production. Regional myocardial blood flow in all layers of the heart distal to the stenosis did not change compared with control during the initial 1 microgram.min-1 dose of U46619 but was reduced significantly after the 5 micrograms.min-1 dose (approximately 20% vs control). Distal zone flow (all layers) returned to baseline at control (2) and remained unchanged after indomethacin infusion. Although distal zone flows were reduced significantly in response to the second 5 micrograms.min-1 dose, the reduction in each layer after indomethacin was comparable to that observed with the 5 micrograms.min-1 dose before indomethacin infusion. Finally, the in vitro production of PGI2 by coronary vessels was considerably impaired by indomethacin infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1988

Renal tubular vasopressin receptors downregulated by dehydration.

Receptors for arginine vasopressin (AVP) were characterized in tubular epithelial basolateral membranes (BL membranes) prepared from the kidneys of male Sprague-Dawley rats. Association of [3H]AVP was rapid, reversible, and specific. Saturation studies revealed a single class of saturable binding sites with a maximal binding (Bmax) of 184 +/- 15 fmol/mg protein and a KD of 0.61 +/- 0.04 nM. IC50S for AVP, lysine vasopressin, and oxytocin were 0.74 nM, 9.7 nM, and greater than 1 microM, respectively. The V2 receptor antagonist was more than 3,700 times as effective in displacing [3H]AVP than was the V1 antagonist. To investigate the physiological regulation of vasopressin receptors, the effects of elevated levels of circulating AVP on receptor characteristics were studied. Seventy-two-hour water deprivation significantly elevated plasma osmolality and caused an 11.5-fold increase in plasma [AVP]. Scatchard analysis revealed a 38% decrease in the number of AVP receptors on the BL membranes from dehydrated animals. The high-affinity binding sites on the BL membranes fit the pharmacological profile for adenylate cyclase-linked vasopressin receptors (V2), which mediate the antidiuretic action of the hormone. We conclude that physiologically elevated levels of AVP can downregulate vasopressin receptors in the kidney.

Animals↗
PubMed1988

Vasopressin stimulates phosphoinositide hydrolysis in LLC-PK1 cells.

LLC-PK1 cells have been shown to possess vasopressin (VP) receptors (V2 type) that are coupled to adenyl cyclase to generate adenosine 3,5'-cyclic monophosphate (cAMP). To determine whether VP also stimulates phosphoinositide (PI) hydrolysis to generate inositol phosphate (IP) and diacylglycerol (DAG) messenger system in LLC-PK1 cells, we measured the release of IP in LLC-PK1 cells in the absence and presence of various concentrations of VP. In addition, we also determined the effect of an increase in osmolality of the incubation medium on VP-stimulated PI hydrolysis in LLC-PK1 cells. The methods involved the incubation of LLC-PK1 cells with [3H]inositol for its incorporation into membrane PI and the measurement of the release of [3H]IP in the presence of LiCl which prevents dephosphorylation. The osmolality of the incubation media was increased from 300 to 600, 900, and 1,200 mosmol/kgH2O by the addition of NaCl and urea. In an isosmotic incubation medium, VP (10(-8) M) produced a 100% increase in PI hydrolysis in LLC-PK1 cells. The effect was much greater at higher concentrations of the hormone. There was no effect of osmolality in VP-stimulated PI hydrolysis in LLC-PK1 cells up to 600 mosmol/kgH2O, but PI hydrolysis decreased significantly when the osmolality of the incubation medium was increased to 900 or 1,200 mosmol/kgH2O. Our results suggest that in LLC-PK1 cells, VP stimulates PI hydrolysis probably through VP receptors that are coupled to phospholipase C. Furthermore, VP-stimulated PI messenger system in LLC-PK1 cells is influenced by osmolality of the extracellular fluid.

Animals↗
PubMed1988

Characteristics of borderline personality disorder: a Canadian study.

This study presents data on a Canadian sample of inpatients with the diagnosis of Borderline Personality Disorder (BPD). Inpatients with BPD were compared to inpatients with borderline traits. The results indicate that the BPD inpatients have a chronic severe disorder, which onsets in adolescence, and are likely to have suffered early deprivation or abuse.

Adult↗
PubMed1988

Biological markers in borderline personality disorders: an overview.

The state of knowledge in the area of suggested biological markers that may delineate subpopulations of patients with borderline personality disorders (BPD) is reviewed. There is widespread disagreement as to the specificity of these markers. The clinical implications of Axis I--Axis II, state vs. trait, acute vs. chronic, and definite vs. probable diagnoses, all seem to contribute to the confusion in this area. Some patients with BPD and with schizotypal personality disorders (SPD) share neuroendocrine abnormalities with affective disorders (AD) and schizophrenic (SCH) patients respectively. This interface and/or potential overlap between personality disorders (PD) and the major mental disorders is discussed with special reference to the DST, TRH/TSH test, and REM latency which have already been established as valuable biological markers for certain subtypes of depression. In contrast, biologic abnormalities observed in chronic schizophrenia are also present in some SPD patients. Current data are supportive of the hypothesis that some PD patients are independent whereas others are genetically related to the major mental disorders.

Borderline Personality Disorder↗
PubMed1988

Psychopharmacologic management of patients with borderline personality disorder.

This paper reviews recent literature on the psychopharmacologic management of borderline personality disorder (BPD) patients and discusses an approach to drug therapy. Five randomized controlled trials have shown positive, but non-specific effects of antipsychotic drugs on the symptoms suffered by BPD patients. There were too few data on other types of drugs to draw any conclusion. We propose that BPD patients be treated on the basis of being in a state or episode of co-existing Axis I disorder.

Borderline Personality Disorder↗
PubMed1988

Influence of serotonin on myocardial blood flow in the presence and absence of a coronary arterial stenosis: observations in domestic swine.

This study tested the hypothesis that 5-HT may impair coronary flow regulation by inappropriately increasing arteriolar tone in the coronary circulation. Ten closed chest, domestic swine were studied both in the presence and in the absence of a severe artificial intraluminal coronary stenosis. A 5-French micromanometer catheter with fluid lumen was placed in the left anterior descending coronary artery and used to record pressure and infuse 5-HT (40 and 100 micrograms/min) into the coronary circulation. For the stenosis phase of the protocol the catheter was embedded in the artificial stenosis. Hemodynamics, regional myocardial blood flow (microsphere technique), coronary vascular resistance, lactate consumption, and oxygen metabolism were measured at control and at 5 min of each 5-HT dose. In the absence of coronary artery stenosis (i.e., full vasodilatory reserve), there was no change in regional myocardial blood flow or coronary vascular resistance during 5-HT infusion. In the presence of a severe coronary stenosis (i.e., limited vasodilator reserve) 5-HT produced a significant (P less than 0.05) decrease versus control in the distal left anterior descending: circumflex zone endocardial blood flow ratio (0.63 +/- 0.19, mean +/- 1 SD, to 0.55 +/- 0.15) and a significant (P less than 0.05) increase versus control in endocardial (50.6 +/- 16.6 to 61.2 +/- 19.8 mm Hg/ml/min/g) and transmural (49.9 +/- 9.5 to 57.2 +/- 12.8) coronary vascular resistance. Thus, 5-HT does not impair coronary flow regulation when full vasodilatory reserve is present. When coronary vasodilatory reserve is impaired by the presence of a severe proximal stenosis, 5-HT causes modest impairment of endocardial flow regulation.

Animals↗
PubMed1988

[Visual evoked potentials as affected by different modes of stimulation].

VEP with 3 different modes of stimulation (pattern-reversal, flash and light-emitting diodes = LED) were performed in 30 subjects with normal vision. Normal values were established and the main components were compared under these 3 conditions of stimulation. The latencies of the main components showed a normal distribution in pattern-reversal and flash stimulation mode, but not in LED stimulation modes. The latency of the main component P2 of pattern reversal stimulation mode as well as the amplitude showed the smallest variance; flash and LED stimulation mode had a longer latency of the main component than pattern reversal stimulation mode. No sex or side differences were observed. In one subject (3%) the main component (P2) of pattern-reversal stimulation mode had a W-form, in LED stimulation mode 63% and in flash stimulation mode 40% of the subjects showed a W-form of the main component. The main component (P2) of pattern-reversal stimulation mode was best correlated with the first component of a W-from in flash and LED stimulation mode. Therefore, from one latency value (LED or flash stimulation mode) a latency value of pattern reversal stimulation mode may be estimated.

Adult↗