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Biomedical subjects

A Alter

Publications and source records attributed to A Alter.

At least 19 recordsLinked to original sources
PubMed2001

Device-guided breathing exercises reduce blood pressure: ambulatory and home measurements.

Slow breathing practiced routinely using an interactive device has demonstrated a sustained reduction in high blood pressure (BP). We reevaluated the BP response of hypertensives (n = 13) to this daily treatment for 8 weeks using 24-h ambulatory, home, and office BP measurements. A clinically significant BP reduction of similar magnitude was observed in all BP monitoring modalities during the daytime. Greater BP reductions were found for older patients and higher baseline BP. The results provide additional support for the efficacy of the device as an adjunctive lifestyle modification for treating hypertension.

Adult↗
PubMed1998

Ultrasound inhibits the adhesion and migration of smooth muscle cells in vitro.

This study investigated in vitro the effect of therapeutic ultrasound (ULS) on smooth muscle cell (SMC) function as adhesion, migration and proliferation. Experiments were conducted on aortic SMC in culture. The LD50 was established (1.5 W for 15 s at a frequency of 20 kHz) and used as standard dose in all experiments. Control SMC and viable sonicated SMC were compared in each experiment. Migratory capacity decreased 2.4-fold after sonication and stayed reduced for up to 24 h. Adhesion capacity decreased 5.5-fold after ULS. The proliferative capacity was similar to that of nonsonicated SMC. Sonication was accompanied by the disorganization of alpha-SM actin fibers and diminished distribution of vinculin; tyrosinated alpha tubulin and vimentin appeared unaffected. These changes might be responsible for the observed inhibition of SMC adhesion and migration. Sonicated cells exhibited less lamellipodia, membrane collapse and bleb formation. The signal transduction cascade, which involves activation of the phospholipase-C pathway, was unaffected by ULS.

Animals↗
PubMed1995

Safety of coronary ultrasound angioplasty: effects of sonication on intact canine coronary arteries.

The purpose of this work was to examine in vivo the safety of sonication in the coronary arteries in a live animal model. In intact dogs (n = 8), balloon dilatation was performed on the proximal left anterior descending artery (LAD) followed by sonication to the left circumflex artery (LCX) in power levels found to be optimal for thrombus ablation. Post-dilatation and post-ultrasound coronary angiography, echocardiography, histopathology, CK-MB, indices of hemolysis, and coagulation were compared. Sonication did not induce changes in the ECG or blood pressure. Coronary angiography revealed no adverse side effects or change in arterial diameter (2.3 +/- 0.7 vs. 2.4 +/- 0.3 mm). Echocardiography showed transient opacification of the myocardium. Histopathology revealed a comparable minimal degree of endothelial denudation. After sonication there were no changes in the level of CK-MB (312 +/- 168 vs. 283 +/- 207 IU), hemoglobin (11.3 +/- 0.9 vs. 12.7 +/- 1.1 gr%), haptoglobin (479 +/- 136 vs. 451 +/- 121 mg/dL), fibrinogen (142 +/- 18 vs. 165 +/- 28 mg%), partial thromboplastin time (17.3 +/- 3.2 vs. 17.6 +/- 3.4 sec), prothrombin time (13.3 +/- 7.8 vs. 11.5 +/- 2.9 sec), and degree of platelet aggregation (55 +/- 17 vs. 62 +/- 8%). Thus, the data suggest that transluminal coronary sonication exerts no overt adverse effects in vivo.

Angioplasty, Balloon↗
PubMed1995

Total knee replacement. A guideline to reduce postoperative length of stay.

In a retrospective study in an academic, acute-care community hospital, we studied the possible safety and effectiveness of a practice guideline recommending early discharge from the hospital for patients having uncomplicated total knee replacement. Of 206 patients receiving knee replacements, 162 (79%) were classified by the guideline as being at low risk for complications between the 4th and 7th postoperative days. Use of the guideline could have reduced the postoperative length of stay from 7.3 +/- 2.6 days to 4 days for the 112 patients (54%) who became low risk on the 4th postoperative day. Explicit and implicit review of the quality of care determined that 157 patients (96.9%; 95% confidence interval, (92.9%, 99.0%) could have been safely transferred from the acute-care hospital to an appropriate setting when they became classified at low risk between the 4th and 7th postoperative days. Clinical practice guidelines can possibly be used to reduce the postoperative length of acute-care hospital stay for patients having knee replacements. This guideline requires further study in a controlled clinical trial before it can be recommended for use.

Aged↗
PubMed1994

Hip replacement and hip hemiarthroplasty surgery: potential opportunities to shorten lengths of hospital stay.

The potential safety and effectiveness of a practice guideline recommending a 5-day postoperative stay in the acute care hospital for hip surgery patients without clinical findings predictive of a complicated hospital course was studied retrospectively in 230 patients hospitalized for total hip replacement, total hip replacement with osteotomy, or hip hemiarthroplasty. Seventy percent of total hip replacement and hip hemiarthroplasty patients were classified as being at "low risk" for complications by the guideline (161 patients, or 73% of patients who remained hospitalized). Use of the guideline could have reduced the hospital length of stay from 8.4 days (standard deviation 3.3) to 5.9 days for these selected low-risk patients. Moreover, physicians' implicit review determined that 0% of patients (95% confidence interval, 0% to 2.3%) had a complication that would have benefited from continued stay in an acute care hospital after the fifth postoperative day. Our practice guideline may have the potential to safely reduce acute care hospital length of stay for patients recovering after total hip replacement and hip hemiarthroplasty. The guideline will require further study in a prospective clinical trial before it can be recommended for widespread use.

Aged↗
PubMed1993

Enhanced receptor-dependent inositol phosphate accumulation in hypoxic myocytes.

The arrhythmogenic effects of alpha 1-adrenergic receptor agonists are enhanced in the ischemic myocardium. The present study was designed to determine whether hypoxia influences alpha 1-receptor subtype activation of phosphoinositide hydrolysis in neonatal rat ventricular myocyte cultures. Hypoxia did not alter basal inositol phosphate accumulation, but markedly increased norepinephrine-dependent inositol phosphate accumulation. This effect was apparent within 30 min and readily reversed on 30 min of reoxygenation. The response to norepinephrine reflected activation of a specific alpha 1-adrenergic receptor subtype; it was inhibited by prazosin and WB-4101 but not by chloroethylclonidine or propranolol. The density of alpha 1-adrenergic receptors identified by [125I]IBE-2254 was similar in normoxic and hypoxic myocytes. Consistent with this observation, the response to a maximal concentration of norepinephrine was enhanced by hypoxia, but the half-maximum effective dose for norepinephrine was not modified. The effects of isoproterenol to stimulate adenosine 3',5'-cyclic monophosphate (cAMP) accumulation and of carbachol to inhibit isoproterenol-stimulated cAMP accumulation were not influenced by hypoxia. In contrast, inositol phosphate accumulation in response to carbachol or thrombin was markedly increased in hypoxic myocytes. These results demonstrate an effect of hypoxia to enhance phosphoinositide hydrolysis through a mechanism(s) distal to the receptor that may have important implications with respect to calcium overload and electrical abnormalities during myocardial ischemia.

Animals↗
PubMed1990

Stimulation of human T cell colony growth by a lymphocyte colony enhancement factor derived from lymphocyte subpopulations.

Blood mononuclear cells (MNC) develop into T cell colonies when the cells are sensitized with PHA and seeded in a two-layer soft agar system. Conditioned medium (CM) derived from MNC enhanced lymphocyte colony formation when it was added to the culture system. CFU-TL appear to be stimulated into colony formation by molecules secreted by lymphocyte subpopulations contained in the seeded cells. In this study, human peripheral blood MNC were fractionated by a battery of techniques into adherent, E+, CD4+, CD8+, B and null cells. CM was prepared from each of the subpopulations and its effects on T cell colony growth assayed. All the lymphocyte subpopulations were found to generate lymphocyte colony enhancement factor (LCEF). After several purification procedures, CM prepared from CD4 and CD8+, displayed LCEF activity corresponding to proteins of molecular weight 30-40 and 100-140 kD.

Antigens, CD↗
PubMed1989

Characterization of the interference of T cell activation by reserpine.

It has been suggested that reserpine blocks expression of delayed hypersensitivity (DH) reactions by depleting tissue mast cells of serotonin, thereby preventing a T cell-dependent release of mast cell serotonin necessary to localize and to amplify the DH response. However, reserpine blocks expression of DH in mast cell-deficient mice. Recently, we showed that the ability of reserpine to interfere with the expression of contact sensitivity was independent of an effect on mast cells, but reflected an effort of the drug on effector T cell function. In the present study we evaluated the mechanisms by which reserpine abrogates the expression of T cell functions. By using human peripheral blood mononuclear cells or enriched T cell populations we found that the drug inhibited, in a dose-dependent fashion, the proliferation of T cells after mitogen stimulation. Reserpine also interfered with the mitogen-induced IL-2 production by these cells, but the IL-2 receptor expression, as measured by immunofluorescence, was unaffected. Despite this, in the continuous presence of reserpine, exogenous IL-2 did not bypass reserpine inhibition of PHA-induced proliferation. By using the fluorescent indicator quin-2 we have demonstrated that preincubation with reserpine prevented the increase of cytosolic free calcium, which accompanies PHA-induced proliferative responses of human T lymphocytes. These results identify the sites of action of reserpine in human T lymphocytes and are sufficient to explain its ability to block cell-mediated immune responses in vitro and in vivo.

Antigens, CD↗
PubMed1984

Biochemical and histological anomalies in the rat hepatic tissue following administration of bichromate and nickel in ionized form.

Administration of bichromate ions at a dose of 60 mg/kg body wt to female rats, reduced dramatically both hepatic microsomal cytochrome P-450 content and the monooxygenase activities assayed, namely: N-demethylation of aminopyrine and O-demethylation of p-nitroanisole. At the same dose the bichromate ion treatment caused a substantial decrease in cytochrome b5 content, but there was no significant reduction in NADPH-cytochrome c reductase activity. Administration of phenobarbital to bichromate ion pretreated rats did not induce a significant increase in cytochrome P-450 content nor in aminopyrine N-demethylase activity. Administration of nickel ions at a dose of 60 mg/kg body wt to female rats did not reduce to a significant level the content or the activity of any of the hepatic microsomal enzymes mentioned above, but did interfere in the de novo synthesis of cytochrome P-450 following phenobarbital treatment. The concentrations of nickel residues in the hepatic tissue of treated rats were only 5.8 times higher compared to the control rats, while those of chromium were 42 times higher than in control rats. Histological changes associated with the increase of bichromate concentration in treated rats were the formation of necrotic areas in the hepatic tissue and partial disintegration of the glomeruli and tubules in the kidney.

Aminopyrine N-Demethylase↗
PubMed1984

Corrosion in metal implants embedded in various locations of the body in rats.

Corrosion in metal implants (stainless steel 316L) was followed up in 25 rats for periods of 1.5 to 14.0 months after insertion into the femur, back muscles, or as an external fixation of the tibia using light and scanning electron microscopy. In the implants buried in the back muscles and as an external fixation, mainly "face" and pitting corrosion were detected in 90% of the implants, while in the intramedullary implants crevice, pitting and various "holes" of irregular shape were evident in all implants. Calcium and phosphate deposits were also found on the intrafemoral implants. The corrosion in the implants was detected as early as 1.5 months but was quite variable. However, a progressive increase in the corrosion occurred concomitant with the length of time after implantation. The question is whether stainless steel metal implants presently in clinical use can be considered innocuous.

Animals↗
PubMed1980

Detection of retroperitoneal hemorrhage after translumbar aortography by computerized tomography.

Thirty-seven patients were examined by CT scan within 24 hours of translumbar aortography. Eighteen of them had signs of hemorrhage, of which psoas asymmetry was the most common. Para-aortic densities and obliteration of the aorta were the next most frequent manifestations. CT scanning can be a useful tool in selected cases to detect or follow hemorrhage after aortography by the translumbar approach.

Aged↗