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Biomedical subjects

G Steinberg

Publications and source records attributed to G Steinberg.

At least 55 records · Page 3Linked to original sources
PubMed1994

Protection against focal cerebral ischemia following exposure to a pulsed electromagnetic field.

There is evidence that electromagnetic stimulation may accelerate the healing of tissue damage following ischemia. We undertook this study to investigate the effects of low frequency pulsed electromagnetic field (PEMF) exposure on cerebral injury in a rabbit model of transient focal ischemia (2 h occlusion followed by 4 h of reperfusion). PEMF exposure (280 V, 75 Hz, IGEA Stimulator) was initiated 10 min after the onset of ischemia and continued throughout reperfusion (six exposed, six controls). Magnetic resonance imaging (MRI) and histology were used to measure the degree of ischemic injury. Exposure to pulsed electromagnetic field attenuated cortical ischemia edema on MRI at the most anterior coronal level by 65% (P < 0.001). On histologic examination, PEMF exposure reduced ischemic neuronal damage in this same cortical area by 69% (P < 0.01) and by 43% (P < 0.05) in the striatum. Preliminary data suggest that exposure to a PEMF of short duration may have implications for the treatment of acute stroke.

Animals↗
PubMed1994

The pKa of the protonated Schiff bases of gecko cone and octopus visual pigments.

A visual pigment is composed of retinal bound to its apoprotein by a protonated Schiff base linkage. Light isomerizes the chromophore and eventually causes the deprotonation of this Schiff base linkage at the meta II stage of the bleaching cycle. The meta II intermediate of the visual pigment is the active form of the pigment that binds to and activates the G protein transducin, starting the visual cascade. The deprotonation of the Schiff base is mandatory for the formation of meta II intermediate. We studied the proton binding affinity, pKa, of the Schiff base of both octopus rhodopsin and the gecko cone pigment P521 by spectral titration. Several fluorinated retinal analogs have strong electron withdrawing character around the Schiff base region and lower the Schiff base pKa in model compounds. We regenerated octopus and gecko visual pigments with these fluorinated and other retinal analogs. Experiments on these artificial pigments showed that the spectral changes seen upon raising the pH indeed reflected the pKa of the Schiff base and not the denaturation of the pigment or the deprotonation of some other group in the pigment. The Schiff base pKa is 10.4 for octopus rhodopsin and 9.9 for the gecko cone pigment. We also showed that although the removal of Cl- ions causes considerable blue-shift in the gecko cone pigment P521, it affects the Schiff base pKa very little, indicating that the lambda max of visual pigment and its Schiff base pKa are not tightly coupled.

Animals↗
PubMed1993

pKa of the protonated Schiff base of bovine rhodopsin. A study with artificial pigments.

Artificial bovine rhodopsin pigments derived from synthetic retinal analogues carrying electron-withdrawing substituents (fluorine and chlorine) were prepared. The effects of the electron withdrawing substituents on the pKa values of the pigments and on the corresponding Schiff bases in solution were analyzed. The data suggest that the apparent pKa of the protonated Schiff base is above 16. However, the alternative possibility that the retinal Schiff base linkage in bovine rhodopsin is not accessible for titration from the aqueous bulk medium cannot be definitely ruled out.

Animals↗
PubMed1993

An intervention that delays institutionalization of Alzheimer's disease patients: treatment of spouse-caregivers.

Spouse-caregivers of Alzheimer's disease patients were randomly assigned to either a treatment group (individual and family counseling, support group participation, and ad hoc consultation) or a control group (only routine support). In the first year after intake, the treatment group had less than half as many nursing home placements as the control group. This suggests that a comprehensive counseling program can reduce the socioeconomic impact of Alzheimer's disease. Nursing home placement also was affected by the patient's need for assistance with activities of daily living, patient income, and the age of the patients and caregivers.

Aged↗
PubMed1993

Organelle movements in the wild type and wall-less fz;sg;os-1 mutants of Neurospora crassa are mediated by cytoplasmic microtubules.

The cellular basis of organelle transport in filamentous fungi is still unresolved. Here we have studied the intracellular movement of mitochondria and other organelles in the fungus Neurospora crassa. Four different model systems were employed: hyphae, protoplasts, a cell wallless mutant, and experimentally generated small, flattened cell fragments of the mutant cells. Organelle movements were visualized by DIC optics and computer-enhanced video microscopy. In all cell models the transport of organelles was vectorial and saltatory in nature. The mean velocities for mitochondria, particles and nuclei were 1.4, 2.0, and 0.9 microns/s, respectively. Treatment with 10 microM nocodazole for 30 minutes caused a complete disappearance of microtubules and reversibly blocked directed transport of virtually all organelles, whereas cytochalasin D up to 20 microM was without effect. Correlative video and immunofluorescence microscopy of small fragments of wall-less mutant cells revealed a clear match between microtubule distribution and the tracks of moving organelles. We conclude that organelle movement in the filamentous fungus Neurospora crassa is a microtubule-dependent process.

Actins↗
PubMed1993

Localized hypertrophic mononeuropathy of the trigeminal nerve.

We report a case of localized hypertrophic mononeuropathy that involved the trigeminal nerve in a 61-year-old woman with a 5-year history of progressive drooping of the left eyelid, double vision, and left-sided temporal and retro-orbital pain. A mass that occupied the patient's left cavernous sinus was found to display localized hypertrophic mononeuropathy characterized by "onion bulbs" that were formed of concentrically proliferating Schwann cell processes around intact axons. This contrasted to the majority of previously reported cases of localized hypertrophic mononeuropathy, predominantly found in peripheral nerves, where the proliferating cell processes have been shown to be of a perineurial cell origin. Differences in architectural arrangement and degree of cellularity between the perineurial and schwannian forms of localized hypertrophic mononeuropathy were noted. These findings suggest important fundamental differences in the pathogenesis of various forms of onion-bulb mononeuropathies.

Cranial Nerve Diseases↗
PubMed1991

Prostatic duct adenocarcinoma. Findings at radical prostatectomy.

Previous studies of prostatic duct adenocarcinoma have reported a poor prognosis, but they included few patients treated by radical prostatectomy. The authors studied 15 cases treated with radical prostatectomy to define more completely their pathologic features and determine the clinical outcome in these surgically treated patients. The study included morphometry and DNA image analysis using the CAS-200 system. The most common presentation was urinary outlet obstruction (n = 9), and most patients were clinical Stage B with palpable prostatic lesions (n = 12). Compared with acinar cancers of similar clinical stage, duct cancers were large (tumor volume, 8.4 +/- 10.0 cc) and occupied a large portion of the gland (23 +/- 21%). Duct cancers were in an advanced final pathologic stage with 93% having capsular penetration, 47% positive margins, 40% seminal vesicle invasion, and 27% positive pelvic lymph nodes. The DNA analysis on cells disaggregated from paraffin revealed that 54% of cases were diploid, 15% tetraploid, 8% aneuploid, and 23% tetraploid/aneuploid. On clinical follow-up, eight patients had no evidence of tumor at intervals ranging from 1 to 28 months, and seven patients (47%) had persistent tumor at intervals of 3 to 18 months. This study demonstrates that duct cancers are in an advanced pathologic stage by the time of presentation and have a much higher short-term failure rate after radical prostatectomy compared with acinar cancers.

Adenocarcinoma↗
PubMed1989

Clinical characteristics and natural history of survivors of pulmonary congestion during acute myocardial infarction. The Multicenter Postinfarction Research Group.

Although pulmonary congestion during acute myocardial infarction (AMI) is recognized as an important adverse event, the detailed clinical features, natural history and predictive value of standard diagnostic tests in such patients have not been well characterized. As part of a multicenter prospective postinfarction trial, 123 patients with pulmonary congestion during AMI, who survived and were discharged from the coronary care unit, were studied. These patients were compared with similar patients who did not develop pulmonary congestion. Patients with pulmonary congestion had a significantly higher 1-year mortality rate compared with 744 patients without pulmonary congestion during AMI (28 vs 5.5%). Patients with pulmonary congestion were characterized by a lower ejection fraction, more frequent anterior infarction, diminished ability to perform exercise testing and higher incidence of subsequent cardiac events. Even without these variables, pulmonary congestion was associated with increased mortality. In patients with pulmonary congestion, ejection fraction (dichotomized at 30%) and exercise testing were the most discriminating tests in risk stratification. An ejection fraction greater than 30% and completion of the exercise test was associated with a 7% mortality while an ejection fraction less than 30% and inability to take or complete the exercise test was associated with a 44% 1-year mortality. A greater incidence of reinfarction, ischemia during exercise and ischemic events at the time of death in the pulmonary congestion group suggests that ischemia may be an important factor in this high risk category.

Aged↗
PubMed1989

Reorganizing ambulatory services for the 1990s: challenges and issues.

With the increased demand for care rendered in an ambulatory setting, hospitals are finding that they must reorganize their service complement and locations to keep up with market demand and respond to competitor initiatives. This issue of DRG Monitor describes an approach to determining what needs to be done, addresses factors that should be considered, and provides a model derived from a case study of a hospital. This approach goes beyond the tradition of viewing each department and/or service that offers ambulatory care as an entity unto itself. Instead, this paper illustrates how hospitals can look at the ambulatory components of departments and services from a product-line perspective so that they can maximize efficiency and link related areas in order to build upon their respective market potentials.

Hospital Administration↗
PubMed1987

Institutionalization of Alzheimer's disease patients: reducing precipitating factors through family counseling.

Although home-care of Alzheimer's disease (AD) patients is more cost-effective than institutionalization, there is limited knowledge concerning the causes and prevention of institutionalization. The goal of this project was to determine the circumstances related to institutionalization of AD patients and to determine if a family counseling program can reduce these precipitating factors. In Study 1, we surveyed 109 family members of institutionalized AD patients. Primary precipitating factors included difficulties with patient behavior, insufficient auxiliary help and respite, financial difficulties, and caregiver emotional and physical complaints. In Study 2 we evaluated the effectiveness of an enhanced counseling program which included specific intervention techniques to cope with precipitating factors. For 41 AD family members who were seriously contemplating institutionalization, the precipitating factors prior to counseling were similar to those found in Study 1. After six months of individual counseling, home visits, and participation in caregiver support groups, there was only one placement, and a consistent reduction in the precipitating factors. These preliminary results suggest that a specially designed counseling program may delay or forestall institutionalization.

Alzheimer Disease↗
PubMed1986

Longitudinal course of normal aging and progressive dementia of the Alzheimer's type: a prospective study of 106 subjects over a 3.6 year mean interval.

Elderly, community residing subjects (N = 106; mean age = 70.6 +/- 6.02 years) with cognitive functioning consistent with normal aging or dementia of the Alzheimer's type (DAT), were followed over a 3.6 year mean interval (range = 2.78 to 5.12 years). All subjects were assessed at baseline on the Global Deterioration Scale (GDS), a global clinical instrument reflecting the continuum of cognitive dysfunction from normal aging to severe DAT. At follow-up subjects were reassessed with respect to mortality, institutionalization and clinical change, defined as at least a two-point change on the 7-point GDS. Our results suggest that patients at deterioration levels GDS greater than or equal to 4, are more likely to show negative outcomes, specifically, institutionalization (Ps less than .001), death (Ps less than .01), or, for the community residing remainder, clinical deterioration (Ps less than .05), than subjects from less impaired (GDS = 2 or GDS = 3) subject groups. Seventy-six per cent of subjects at deterioration levels four or greater (N = 34) had negative outcomes at follow-up, whereas ninety percent of subjects with deterioration levels less than four (N = 72) did not.

Aged↗
PubMed1984

Effects of long-term molsidomine treatment versus isosorbide dinitrate and placebo on exercise tolerance in stable angina.

A single-blind study (n = 59) was performed to assess the effect of long-term (4 week) orally administered molsidomine (2 mg 4 X daily), isosorbide dinitrate (10 mg 4 X daily), and placebo on exercise tolerance performed on the bicycle ergometer by patients with stable angina on effort and with significant coronary artery disease. Isosorbide dinitrate had similar effects to placebo, both failed to modify the pressure-rate product, the sustained work load, and the ST segment depression, but slightly decreased, although not significantly, the incidence of angina. Although not affecting the pressure-rate product and the mean blood pressure, molsidomine decreased significantly the ST segment depression (p less than .05). In conclusion, by markedly reducing preload and because of its long-lasting effect (up to 6 h), the new vasodilator drug molsidomine plays a useful role in the long-term management of stable angina on effort.

Angina Pectoris↗