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Biomedical subjects

S Levine

Publications and source records attributed to S Levine.

At least 235 records · Page 13Linked to original sources
PubMed1990

Acute obstructive parasternal lymphedema produced in rats without surgery.

Although rat red blood cells (RBC) were altered by pretreatment with glutaraldehyde, they nonetheless were well absorbed into mediastinal lymphatics of Lewis rats after intraperitoneal injection. Unlike normal RBC, they did not pass freely through the draining mediastinal lymph nodes. Instead, clumps of free and phagocytosed glutaraldehyde-treated RBC distended and obstructed the afferent lymphatics and the sinuses of draining lymph nodes. The lymphatic obstruction caused edema in a clearly defined compartment of fatty connective tissue between the muscle layers of the ventral chest wall. The obstructive lymphedema interfered with the immunizing effect of small doses of sheep RBC injected intraperitoneally. This study emphasizes the potential utility of the rat's mediastinal lymphatics for studies of lymphatic leakage and obstruction.

Animals↗
PubMed1990

Negative-pressure ventilation.

In this review, we make the following major points: (1) Canine experiments indicate that in an experimental model of ARDS, cyclic NPV plus NEEP is as effective as cyclic PPV plus PEEP in treating arterial hypoxemia. Because cyclic NPV plus NEEP does not depress cardiac output as much as cyclic PPV plus PEEP, further study of this potential therapy is warranted. (2) At the present time, NPV has little use in neonatal medicine. (3) However, in adult medicine, NPV is efficacious for providing chronic ventilatory support in patients with neuromuscular and chest wall diseases. Additionally, the role of NPV in postoperative weaning warrants further study. (4) Some data in the literature suggest that some subsets of patients with CAL may benefit from chronic intermittent NPV therapy. However, criteria for identifying these patients have not been established. (5) Some investigators have recently demonstrated that PPV delivered via the nares can elicit VMR. Because this technique provides us with the opportunity to elicit VMR by a method other than NPV, nasal PPV provides us with a method to directly validate our presumption that improvements in COPD patients are related to VMR per se.

Adult↗
PubMed1990

A report of eight HIV-seropositive patients with major depression responding to fluoxetine.

This pilot study examined the effectiveness of fluoxetine in depressed human immunodeficiency virus (HIV)-seropositive asymptomatic patients. Eight patients, participating in an AZT trial who met criteria for major depression syndrome (DSM-III-R), were treated with fluoxetine (20 or 40 mg/day) for 4 weeks. Initially, mean Hamilton Depression scores were 23.8 (range of 17-31), and improved to 6.4 (range of 3-10). All subjects maintained their remission over a 2-month follow-up. Fluoxetine treatment may be effective in treating major depression in HIV-seropositive asymptomatic patients.

Adult↗
PubMed1990

Lymphatic metastases from the peritoneal cavity are increased in the postinflammatory state.

Cell suspensions of chemically induced tumors (rhabdomyosarcoma) were transplanted into the peritoneal cavities of Lewis rats. In normal animals, the greater omentum was the main site of tumor growth, and transdiaphragmatic metastases to regional lymph nodes in the mediastinum were few and small. In animals during the healing phase of a chemical peritonitis, the greater omentum was fibrotic, shrunken, and inactivated. The loss of the scavenging function of the omentum was associated with wide dissemination of the tumor in the peritoneal cavity and increased access of the tumor to the lymphatic stomata on the peritoneal surface of the diaphragm. Number and size of transdiaphragmatic metastases in draining lymph nodes were greatly increased in this postinflammatory state.

Animals↗
PubMed1989

Inescapable versus escapable shock modulates long-term potentiation in the rat hippocampus.

A group of rats was trained to escape low-intensity shock in a shuttle-box test, while another group of yoked controls could not escape but was exposed to the same amount and regime of shock. After 1 week of training, long-term potentiation (LTP) was measured in vitro in hippocampal slices. Exposure to uncontrollable shock massively impaired LTP relative to exposure to the same amount and regime of controllable shock. These results provide evidence that controllability modulates plasticity at the cellular-neuronal level.

Animals↗
PubMed1989

Effect of gallium on the in vitro formation, growth, and solubility of hydroxyapatite.

Gallium (Ga) is an effective treatment for the hypercalcemia of malignancy. The mechanism of action of the metal in blocking bone resorption in humans is not well understood. This paper examines the effect of Ga on the in vitro formation of hydroxyapatite (HA) in three test systems that have possible biological relevance in a pH-stat at pH 7.4, 37 degrees C, and 0.15 M NaCl: (1) the direct precipitation of HA; (2) the transformation of amorphous calcium phosphate to HA; and (3) the growth of HA seeds. In addition, the effect of Ga on HA solubility was measured at pH 5.0, the approximate pH of osteoclastic bone resorption. Ga decreased the HA formation and/or growth kinetics in a dose-related manner in all three test systems. In addition, the time to the onset of HA formation was increased in systems 1 and 2. Also, the adsorption of Ga on the surface of HA crystals was measured. Ga reduced the dissolution kinetics of HA compared with Ga-free control. The mechanism reported herein--the significant adsorption of Ga on forming and growing HA nuclei and on the surface of HA crystals--is believed to be responsible for the effects of the metal on HA proliferation and solubility. Accumulation of the metal on newly formed metaphyseal bone can now be explained by this adsorption of Ga. These in vitro results partly explain the in vivo action of Ga in treating hypercalcemia by decreasing bone apatite solubility.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium Phosphates↗
PubMed1989

Suppression of experimental allergic encephalomyelitis in rats by mercuric chloride.

Brown-Norway (BN) rats are uniquely susceptible to development of autoimmune phenomena and enlargement of lymph nodes and spleen after repeated injections of mercuric chloride. Despite its ability to produce autoimmunity, HgCl2 inhibited the development in BN rats of experimental allergic encephalomyelitis (EAE), another autoimmune process. The inhibition by mercury was probably due to lack of the normal absorption and granulomatous reaction to the EAE inoculum in the enlarged lymph nodes draining the inoculation site. Lewis rats did not develop enlarged nodes from HgCl2 treatment. Lewis lymph nodes absorbed the EAE inoculum abundantly and developed an extensive granulomatous reaction despite the mercury treatment, and there was only a slight inhibition of EAE. Therefore, the ability of HgCl2 to produce lymphadenopathy in BN rats may be responsible for the inability of these rats to absorb the inoculated antigen. The mercury-induced failure of absorption was manifested as an inhibition of EAE in BN rats.

Animals↗
PubMed1989

Role of the pituitary-adrenal hormones in the acquisition of schedule-induced polydipsia.

Adrenalectomized female rats failed to develop schedule-induced polydipsia (SIP). Dexamethasone (DEX) injections failed to reinstate SIP in adrenalectomized rats. They did not prevent intact rats from acquiring SIP but interfered with subsequent expression of this behavior. In contrast, corticosterone, the rats' normally occurring glucocorticoid, fully restored the acquisition and subsequent expression of SIP in adrenalectomized rats. This strongly suggests that corticosterone plays an essential role in the normal acquisition and development of this behavior. Data are interpreted in the context of current information concerning adrenal hormone receptors. It is hypothesized SIP acquisition is at least partly regulated by the Type I (mineralocorticoid) receptor.

Adrenalectomy↗
PubMed1989

Prediction of lactate threshold and fixed blood lactate concentrations from 3200-m time trial running performance in untrained females.

The present study examined the effectiveness of a 3200-m time trial run for predicting VO2 and running velocity at lactate threshold (LT), and fixed blood lactate concentrations (FBLC) of 2.0, 2.5, and 4.0 mM and peak in untrained women. Thirty-nine female subjects completed a VO2peak/LT test a 3200-m time trial run. Twenty-eight subjects were randomly assigned to a validation sample and the remaining subjects were used for cross-validation purposes. In the validation sample, VO2 measurements at LT, FBLC of 2.0, 2.5, 4.0 mM, and peak were 22.5, 29.2, 31.2, 36.5, and 38.5 ml/kg.min-1, respectively. Velocities at LT, FBLC of 2.0, 2.5, 4.0 mM, and peak were 107.1, 129.7, 136.6, 155.1, and 163.2 m/min, respectively. Regression analysis in the validation group revealed that the 3200-m time trial was an accurate predictor of velocities at LT, FBLC of 2.0, 2.5, 4.0 mM, and peak with correlations of r = 0.70, r = 0.84, r = 0.85, r = 0.87, and r = 0.95, respectively, and standard errors of estimate ranging from +/- 9.5 m/min (for velocity peak) to +/- 13.7 m/min (velocity LT). Vor VO2 prediction, correlations ranged from r = 0.61 (3200-m time vs VO2 LT) to r = 0.77 (3200-m time vs VO2 peak) with the standard errors of estimate ranging from +/- 4.18 (VO2 2.0 mM) to +/- 4.87 ml/kg.min-1 (VO2 4.0 mM).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Percentages of maximal heart rate, heart rate reserve, and VO2peak for determining endurance training intensity in sedentary women.

The use of 60%-95% of maximal heart rate (HR max), heart rate reserve (HRR), and VO2peak as exercise training intensities was examined in sedentary women, and these intensities were related to HR and VO2 observed at the lactate threshold (LT) and fixed blood lactate concentrations of 2.0, 2.5, and 4.0 mM. Thirty-three subjects (means age = 32.5 +/- 3.9 yrs; means ht = 164.2 +2- 5.0 cm; means wt = 67.6 +/- 13.9 kg) completed a VO2/LT treadmill test using a level running protocol. The values at LT, 2.0, 2.5, 4.0 mM, and peak for VO2 were 22.3, 29.0, 31.0, 36.2, and 39.1 ml/kg.min-1, respectively; for velocity were 107.0, 128.9, 135.8, 152.8, and 164.4 m/min, respectively; and for HR were 142.1, 162.9, 169.4, 183.2, and 189.7 bts/min, respectively. The minimum intensity necessary for the majority of subjects to be above LT (n = 17) was 75% HR max while 90% HR max was required for the majority of subjects to be above 2.0 mM (n = 23) and 2.5 mM (n = 19). At 95% HR max 12 subjects were above 4.0 mM. For the majority of subjects to be above LT (n = 18), 55% HRR was necessary; 75%, 85%, and 95% HRR was required for the majority of subjects to be above 2.0 mM (n = 18), 2.5 mM (n = 19), and 4.0 mM (n = 20), respectively. For percent VO2peak, the intensities required for the majority of subjects to be above LT, 2.0 mM, 2.5 mM, and 4.0 mM were 55%, 75%, 80%, and 95% VO2peak, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

The hyperacute form of allergic encephalomyelitis produced in rats without the aid of pertussis vaccine.

The hyperacute form of experimental allergic encephalomyelitis (EAE), characterized by a short incubation period, severe paralysis, high mortality, and abundant polymorphonuclear leukocytes and fibrin in the lesions, was produced in rats without the use of pertussis vaccine (previously considered an essential requirement) or Freund's adjuvant. Carbonyl iron or mineral oil without mycobacteria were effective adjuvants and whole rat spinal cord was the best antigen. Hyperacute EAE was produced in this manner in some Lewis rats, most dark agouti (DA) rats and most F1 hybrids of these two strains. Clinical signs were earlier in onset and more severe in the DA strain than in the Lewis strain in all adjuvant-antigen combinations that were tested. Dark agouti rats developed clinical signs in six days, histological lesions in five days, and localized EAE lesions could be induced in four days. The data support the hypothesis that hyperacute type lesions (neutrophils and fibrin) can be caused by an exceptionally strong immune response to neural antigen, whether that response is engendered by a particular adjuvant (pertussis vaccine) or by an unusual degree of genetic susceptibility (DA rats).

Adjuvants, Immunologic↗
PubMed1989

Inflammatory siderosis of the nervous system in rats.

Large intravenous doses of a relatively nontoxic iron polymaltose complex were taken up by liver and spleen and did not enter the central nervous system (CNS) of normal rats. When the injections were given during development of the inflammatory lesions of experimental allergic encephalomyelitis (EAE), many iron-laden macrophages entered vessels, perivascular cuffs and neural parenchyma. Iron polymaltose injected before the EAE lesions started to develop, or during the healing phase, did not enter the lesions. This model of CNS siderosis may be useful for studies on long-term effects of iron and for neuroimaging by nuclear magnetic resonance.

Animals↗
PubMed1989

Assessment of suicide risk by computer-delivered self-rating questionnaire: preliminary findings.

A prospective study of 167 consecutive patients admitted to a general hospital following an episode of deliberate self-harm was carried out; 102 patients were interviewed by computer and then by a psychiatrist who was blind to the results of the computer interview. The computer interview consisted of a self-rating modification of the Hamilton Rating Scale for Depression and a novel questionnaire developed to assess suicidal ideation. This article explores the preliminary findings in these patients and suggests that not only is the computer interview acceptable to the majority of patients but the data suggest, in line with previous studies, that the patients are prepared to confide information to the computer that they may be unwilling to tell the clinician. Further the data also suggest a significant pathoplastic effect of the personality of the patient on the perception of the psychopathology by the clinician. The computer appeared to be a better predictor of suicidality than the interview by the clinician.

Adult↗
PubMed1989

Enalapril prevents stroke and kidney dysfunction in salt-loaded stroke-prone spontaneously hypertensive rats.

The influence of chronic treatment with the angiotensin I converting enzyme (ACE) inhibitor enalapril on blood pressure, kidney function, and survival was examined in stroke-prone spontaneously hypertensive rats (SHRSP). Male SHRSP that were fed a Japanese rat chow plus a 1% NaCl drinking solution beginning at 7-8 weeks of age developed severe hypertension and stroke; 14 of 18 untreated control SHRSP died by 14 weeks of age and exhibited evidence of cerebrovascular lesions. When enalapril (15 mg/kg/day) was included in the drinking solution of 15 SHRSP, blood pressure was initially reduced by only a slight degree, whereas survival improved markedly; only one of 10 SHRSP died before the rest were killed at 18 to 21 weeks. The remaining five enalapril-treated SHRSP lived beyond 36 weeks and on histological examination exhibited no evidence of cerebrovascular lesions. Chronic enalapril treatment also prevented the greater urinary excretion of protein and severe renal lesions observed in untreated SHRSP but did not affect urinary salt and water excretion. In anesthetized rats, glomerular filtration rate and tubular reabsorption of water were lower in untreated control SHRSP when compared with enalapril-treated SHRSP. Mean arterial pressure was comparable in both groups. These data support a possible role for ACE inhibition in the prevention of stroke and maintenance of kidney function independent of any marked change in blood pressure of SHRSP. Whether the protective effects of ACE inhibition relate to reduced angiotensin II formation, increased tissue kinins, or another mechanism remains to be determined.

Angiotensin II↗
PubMed1989

The envelope proteins from purified respiratory syncytial virus protect mice from intranasal virus challenge.

A lyophilized subunit vaccine prepared from purified respiratory syncytial virus, which contained the envelope glycoproteins F and G and the nonglycosylated matrix protein VPM, was tested in SJL mice for its ability to protect the lungs of mice from intranasal viral challenge. Initially, the mice were injected subcutaneously with one, two, or three doses of 5 or 25 micrograms of vaccine in 50% complete Freund's adjuvant or with complete Freund's adjuvant or phosphate-buffered saline only. Although none of the mice produced neutralizing serum antibody, three doses of 25 micrograms elicited antibodies to F, G, and VPM. Despite the absence of detectable neutralizing antibodies, the lungs of 93% of the vaccinated mice were protected from intranasal viral challenge. Because the initial protocol did not elicit neutralizing antibodies and a few single-dose animals were not protected, a second vaccine trial was carried out. For these studies the priming dose was increased to 50 micrograms, which was followed, in half the vaccine recipients, by a second dose of 25 micrograms. Mice given the priming dose of vaccine produced antibody to G and showed no neutralizing activity, whereas the mice given two doses of vaccine produced antibodies to G, F, and VPM and also displayed neutralizing activity for respiratory syncytial virus. The lungs of 100% of the vaccine recipients in this trial were protected from intranasal challenge. Although the vaccine elicited antibody to VPM, this response did not correlate with protection. In addition, examination of the sera from unimmunized mice recovering from respiratory syncytial virus infection revealed a serum antibody profile similar to that noted for humans, lacking antibody to VPM. Thus, the data show that a combined glycoprotein subunit vaccine affords complete protection to viral challenge and offers an approach to develop a multivalent subunit vaccine.

Administration, Intranasal↗
PubMed1989

[Venezuelan equine encephalitis. Review].

The Venezuelan equine encephalomyelitis (VEE) is one the most serious viral infections of the nervous system. It has a wide geographic distribution and may give rise to sequela like mental retardation, amnesia, abortion, epilepsy and hidroanencephaly in infected humans and animals. The pathology of this infection is focused mainly in two tissues: lymphohematopoietic and nervous. The VEE virus has a special cytopathic activity on the nervous cells (glia and neurons) while the lesions produced in the myelin are probably a consequence of the immunological response of the host to the infection. The alterations produced by the VEE virus in different neuronal types can originate changes in the brain concentrations of several neurotransmitters and their receptors. Some biochemical modifications that have also been reported could be due to the cytopathic effect of the virus.

Encephalomyelitis, Venezuelan Equine↗
PubMed1989

A comparative trial of a new antidepressant, fluoxetine.

A double-blind clinical trial was undertaken to evaluate clinical efficacy and safety of fluoxetine in comparison with the standard tricyclic antidepressant, imipramine, in the treatment of depressive illness. The opportunity was taken to compare the relationship of some standard measures of depressive illness, two observer based--Hamilton Depression Rating Scale and the Montgomery-Asberg Depression Rating Scale (Montgomery and Asberg, 1979)--and a self-rating scale--Levine Pilowsky Depression questionnaire (Pilowsky et al., 1969).

Clinical Trials as Topic↗