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Biomedical subjects

S Weinstein

Publications and source records attributed to S Weinstein.

At least 19 recordsLinked to original sources
PubMed1992

Age-related changes in hyaluronan, proteoglycan, collagen, and osteonectin synthesis by human bone cells.

Human bone cells grown in culture, representative of a preosteoblastic stage of maturation, produce an extracellular matrix composed of collagen, several noncollagenous glycoproteins, hyaluronan, and four distinct proteoglycans (PGs). The influence of donor age on the levels of expression of these molecules in vitro has not been well characterized. In this study, human bone cells derived from sources ranging from fetal to 60-year-old donors were grown in culture, radiolabeled for 24 h, and the amount of incorporation of [35S]sulfate into PGs, [3H]glucosamine into hyaluronan, [3H]leucine/proline into osteonectin, and [3H]proline into collagen was determined. Cell proliferation was most rapid in fetal-derived bone cells and decreased with increasing age. Total protein and PG synthesis also decreased with increasing age, falling to 1/3 and 1/4, respectively, of fetal levels after age 30. A large chondroitin sulfate PG (Mr approximately 600,000 Da) was the major fetal PG and its levels were highly correlated with cellular proliferation. [3H]Collagen and [35S]decorin levels increased with the increasing age of the donor, reached a maximum in puberty-derived cells, and decreased to 1/3 maximal levels after age 20. The heparan sulfate PG (Mr approximately 400,000 Da) exhibited steady-state levels regardless of donor age. [3H]Osteonectin and [35S]biglycan levels were high in fetal-derived cells and in cells derived from pubescent donors. The percentage of collagen and four proteoglycans associated with the cell layer pool changed with donor age. All fetal-derived PG core proteins possessed more N- and O-linked oligosaccharides than newborn or adult derived PGs.

Aging↗
PubMed1990

Crystals of complexes mimicking protein biosynthesis are suitable for crystallographic studies.

A complex of 70S ribosomes from Thermus thermophilus together with an average of 1.5-1.8 equivalents of PhetRNA(Phe) and a short mRNA chain, composed of 35 +/- 5 uridines, was crystallized under the conditions used for the growth of crystals of isolated ribosomes from the same source. Considering the reproducibility of their growth, their internal order and their shape, the crystals of the complex are superior to those of isolated ribosomes. In accord with previous three-dimensional reconstruction and modeling experiments, we conclude that the complex is less flexible and that an average population of complexes is more homogeneous than that of isolated 70S ribosomes. The crystals of the complex diffract to higher than 15 A resolution and can be irradiated with synchrotron X-ray beam at cryo-temperatures for days without noticeable decay. Since the crystals of the complex are apparently isomorphous with these of the isolated 70S ribosomes (P4(1)2(1)2; a = b = 526; c = 315 A), they should provide tool for phasing as well as for locating the mRNA and tRNA binding sites.

Computer Graphics↗
PubMed1990

Orotactile sensation, gustation and palatability: a pilot study.

The hypothesis that deficits in orotactile sensitivity may affect gustation and palatability is not new. It is supported by animal models employing deafferentation; however, little direct evidence supports the application of the model to humans. Indirect evidence comes from four separate fields: (1) neuroanatomy, (2) physiology, (3) developmental biology, and (4) learning theory. The results of a pilot study with humans provide additional direct evidence that implicates the role of orotactile sensitivity in human gustation. In this pilot study, the oral cavity was topically anesthetized to determine whether gustation would be compromised to a similar extent as orotactile sensitivity. The time course of the degree of anesthesia was determined by prior measurements of oral-tactile sensitivity using an oral air-based aesthesiometer. Different concentrations of NaCl-solution were presented to subjects in order to determine gustatory thresholds before and after anesthesia. Analysis of magnitude-estimation data indicated that there were statistically significant decreases in gustatory sensitivity after anesthesia. Basic and applied implications of this area of research are discussed.

Adult↗
PubMed1990

Uses of orthoclone OKT3 for prophylaxis of rejection and induction in initial nonfunction in kidney transplantation.

We have shown that OKT3 can be safely administered to a varied group of transplant recipients, including a high percentage of diabetics and older patients. Used as a prophylactic agent, OKT3 was associated with a decreased incidence and delayed onset of acute rejection. Effectiveness may be reduced by shortening the course of treatment and/or lowering the dose of concomitant azathioprine. Use of OKT3 in patients with ATN (thereby avoiding use of CyA) may be a beneficial strategy. Stimulation of significant titers of antimurine antibody has not been a common event in this study.

Adolescent↗
PubMed1979

Conformation of gramicidin A channel in phospholipid vesicles: a 13C and 19F nuclear magnetic resonance study.

We have determined the conformation of the channel-forming polypeptide antibiotic gramicidin A in phosphatidylcholine vesicles by using 13C and 19F NMR spectroscopy. The models previously proposed for the conformation of the dimer channel differ in the surface localization of the NH2 and COOH termini. We have incorporated specific 13C and 19F nuclei at both the NH2, and COOH termini of gramicidin and have used 13C and 19F chemical shifts and spin lattice relaxation time measurements to determine the accessibility of these labels to three paramagnetic NMR probes--two in aqueous solution and one attached to the phosphatidylcholine fatty acid chain9 all of our results indicate that the COOH terminus of gramicidin in the channel is located near the surface of the membrane and the NH2 terminus is buried deep within the lipid bilayer. These findings strongly favor an NH2-terminal to NH2-terminal helical dimer as the major conformation for the gramicidin channel in phosphatidylcholine vesicles.

Carbon Isotopes↗
PubMed1979

Facilitated healing of osseous lesions in the canine mandible after electrical stimulation.

A study was performed to investigate the effect of electrical stimulation on the repair of osseous lesions in the canine mandible. Results showed considerably more osteoblastic activity on the electrically stimulated side, with maximal growth nearest the negative electrode. Histologic examination showed healing consisted of the production of intramembranous bone, with no evidence of neoplastic changes. The practical uses of electrical stimulation in the practice of oral and maxillofacial surgery are discussed.

Animals↗
PubMed1978

A comparative anthropometric study of Cook Islands and Australian preschool children.

An anthropometric study was conducted on a sample of preschool children from Mangaia, Cook Islands, and a comparison made with similar measurements made on Caucasian children aged two and four years. At two years there were no differences in height, weight, or fatness as measured by skinfold thicknesses between the populations. By four years, the Mangaian children were shorter, lighter and fatter. It is proposed that this disparity in somatic growth is a result of subtle nutritional deficits in the Mangaian children.

Anthropometry↗
PubMed1978

Longitudinal study of bladder cancer with cytology and biopsy.

A study of urinary cytology and selected mucosal biopsies in conjunction with cystoscopy provided additional information of value in the management of 318 patients with bladder cancer. These procedures were especially helpful in patients with no visible lesions on follow-up cystoscopies in assessing the bladder epithelium, the behaviour of which may be unpredictable in that no further tumours may occur, or they may arise at irregular intervals.

Animals↗
PubMed1977

The effect of adenosine-3':5'-cyclic monophosphate on the mitotic rate in regenerating Dugesia dorotocephala.

Regenerating posterior sections of the flatworm, Dugesia dorotocephala, were treated with varying concentrations of 5'-adenosine monophosphate (AMP), cyclic AMP (cAMP) and dibutyryl cyclic AMP (Bt2cAMP) for 24 h. M/2000 colchicine was added to the medium during the final 4 h of treatment to collect mitotic figures. The mitotic rate was significantly increased at 0.5, 0.1 and 0.01 mM concentrations of Bt2-cAMP. While Bt2cAMP and cAMP produced comparable results at 0.01 mM, only the Bt2-cAMP-treated organisms exhibited a significantly higher mitotic rate at the 0.1 mM concentration. Theophylline and sodium butyrate did not evoke any stimulatory effect on mitotic rate.

Adenosine Monophosphate↗
PubMed1977

Effects of local anesthetics on tactile sensitivity thresholds for cutaneous and mucous membranes.

New, reliable, and precise methods for measuring absolute pressure sensitivity in mucous membranes and on intact skin are described. Studies were conducted to determine how local anesthetics (phenol and sodium phenolate and Benzocaine) affect tactile sensitivity thresholds in the oropharynx and on the intact skin of the volar surface of the forearms, ankles, knees, elbows, and dorsum of the hands. Gargling and expectorating a solution containing phenol had a significantly greater anesthetic effect on the mucous membranes of the oropharynx than spraying and swallowing, which, in turn, had a greater effect than drinking the solution. Compared with ethanol and petroleum jelly (Vaseline), the topical application of Benzocaine (0, .5, 1, 3, and 5% solutions in 100% ethanol) significantly increased the tactile sensory thresholds on the volar surface of the forearm. A highly significant loss of tactual sensitivity of the oropharynx was demonstrated in smokers.

Adolescent↗
PubMed1977

Relationship between the electrical (electrocardiographic) and mechanical (echocardiographic) events in Wolff-Parkinson-White syndrome.

Studies using epicardial mapping on patients with Wolff-Parkinson-White syndrome have demonstrated that the delta vector of the electrocardiogram is a detector of the location of at least one bypass tract. In order to relate the electrical activities (preexcitation) with the mechanical activity (septal and ventricular wall motion), echocardiographic strip-chart recordings were obtained in 22 patients with Wolff-Parkinson-White syndrome. Our studies indicated that in the majority of patients with Wolff-Parkinson-White syndrome, left ventricular and septal contraction is normal, suggesting that normal activation predominates and that the determinants of abnormal septal wall motion are (1) the location (right ventricular free lateral wall or septrum) and (2) the degree (duration of the QRS complex greater than 130 msec) of ventricular preexicitation.

Adolescent↗
PubMed1976

The effects of study abroad on health educators' attitudes toward international health efforts.

The major hypothesis of this study was that graduate level course work about internationl health matters carried out in an international setting would reduce hostility and increase cooperativeness in attitudes toward international relations. An eight week program of this type was executed and a comparison of pre- and post-program measurements of these attitudes confirmed the hypotheses. However, it was noted even though statistically significant shifts occured, there were many students who reported negative changes or no change at all. It was also found there were moderately strong correlations between hostility and cooperation. The implications of these findings are that programs of this nature can have a positive impact on attitudes such as these, but that there may be mediating variables tied closely to participant receptiveness to the message of the program; variables which might be important to consider in selection and screening. However, if this were true, it might also be true that those individuals capable of greatest gains may be in least need of such a program and vice versa.

Attitude↗
PubMed1976

Development of neurophysiological indices of retardation: interhemispheric asymmetry of the visual evoked cortical response.

Visual evoked cortical responses (VECRs) were recorded from the left (O1) and right (02) hemispheres at varying interstimulus intervals (ISIs) in children who were either: Normal (dextral), Dextral Retardates, or Sinistral Retardates. Latencies of N1 and P2 components of the VECR were stable and similar for both hemispheres in all groups. There was an asymmetry between the hemispheres for N1-P2 amplitude: right greater than left in Normals; this direction of asymmetry was also present in Sinistral Retardates, but was reversed in Dextral Retardates. The direction of normal VECR asymmetry was the reverse of that previously established for the auditory evoked cortical response (AECR) amplitude (Richlin, et al., 1973; Matsumiya, et al., 1972; Morrell & Salamy, 1971; Wood, et al., 1971). It is suggested that some neural mechanism of the retardates may allow excessive non-verbal stimulation of the normally "verbal" hemisphere. The electrical activity of the brain consequent to auditory or visual stimulation appears to depend upon: the modality of stimulation, the mental status of the individual, and his handedness. These factors have led to the establishment of an additional index to provide differential diagnosis of the mental status of the child.

Adolescent↗
PubMed1976

EMG feedback therapy: review of treatment of 114 patients.

Advances in the understanding of the relationship of proprioceptive (kinesthetic) feedback to motor physiology have prompted the study of therapeutic effects of audiovisual displays of EMG activity. Patients with various manifestations of disturbed neuromotor control were studied prospectively for three years. This group included 114 patients with hemiparesis, torticollis, dystonia, and spinal cord or peripheral nerve injury. Initially, all but one of these patients had some residual volitional motor activity, which was insufficient for adequate function, and all patients had had conventional therapy with little or no functional recovery. Prior to EMG feedback therapy, the duration of illness was from three months to 35 years. The shaping of a patient's motor responses usually occurred gradually, often over an 8 to 12 week period. This modification was accomplished by feeding processed audio-visual signals back to the patient. These signals were proportional to the degree of activity of the muscles responsible for the defective function. The concept of microvolt-second, as a unit of muscle activity, is introduced and defined. Patterned movements, which were previously defective were observed to improve to varying degrees. Following the initial course of treatment, reinforcement was required by some patients. The mechanisms of improvement after EMG feeback therapy are not well understood; however, some hypotheses are presented. The results of this study indicate that EMG feedback therapy may induce significant functional recovery in patients with disturbed neuromotor control.

Activities of Daily Living↗