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Biomedical subjects

M Schwartz

Publications and source records attributed to M Schwartz.

At least 649 records · Page 36Linked to original sources
PubMed1984

Alterations in auditory processing of speech stimuli during aging in healthy subjects.

Studies of auditory processing during aging in man have not provided a consensus on whether aging affects the ability to process speech stimuli. To evaluate the relationship between speech recognition tasks and age, we examined 36 male subjects between the ages of 21 and 83 years, who were screened for the absence of disease, particularly in the cardiovascular and neurologic systems. Measures were obtained on the following tests: pure tone thresholds, speech reception threshold, speech discrimination, low-pass filtered speech, and binaural fusion. A statistically significant correlation was found between pure tone thresholds and age for all frequencies. When the effect of peripheral hearing loss was taken into account, speech measures did not correlate with age, with the exception of low-pass filtered speech in the left ear. Our findings suggest that the aging process in healthy man is not necessarily accompanied by deficits in the processing of speech stimuli beyond those which are due to peripheral hearing loss.

Adult↗
PubMed1984

[Biological studies and research of immunologic deficiencies in blood donors from a prison environment].

The prison population may be considered as a population at risk for AIDS. Biological parameters were studied in order to detect significant anomalies commonly observed in AIDS patients. With respect to are age matched control population of donors, there are no statistically significant differences concerning the nutritional and inflammatory states of the two populations. The investigation of the humoral immunity shows comparable levels of circulating antibodies in the two groups: a high level of anti-cytomegalovirus and anti-herpes antibodies is more frequently found in the penal population. The markers for hepatitis B were also studied. None of the individuals is a carrier of the HBs antigen. The percentage of individuals having biological markers of hepatitis B is higher in the at risk group (45%) than in the control group (10%). The evaluation of the cell-mediated immunity shows that there are no significant differences between the mean values found in the two groups for OKT3, T11, OKT4 and OKT8. There is no inversed OKT4/OKT8 ratio in the at risk group while one donor in the control group shows an inversed OKT4/OKT8 ratio.

Acquired Immunodeficiency Syndrome↗
PubMed1984

[Inflammatory eye changes in the mouse caused by herpesvirus. Changes caused by the cytopathogenic effect. An animal model].

The reproducible inflammatory changes caused by infection with herpes simplex virus (Eidolon-Virus) in the anterior segment in mice represent a useful model. They are very similar to severe inflammation of the eye, as seen in herpes simplex infection. The method used by the authors to damage the corneal epithelium with a local anesthetic is similar to human pathology, in which a disturbance of the protective function of the corneal epithelium also facilitates infection by herpes simplex virus as well. The changes described are a starting point for further investigations.

Animals↗
PubMed1984

Substances originating from the optic nerve of neonatal rabbit induce regeneration-associated response in the injured optic nerve of adult rabbit.

We have recently shown that cell bodies of an injured optic nerve of adult rabbit can be induced to express regeneration-associated response by external signals derived from nonneuronal cells of regenerating nerves of lower vertebrates. In this study it is shown that even substances derived from a nonregenerating mammalian system also can trigger such a regenerative response. Thus, substances derived from intact nerves of neonatal rabbits and of adult rabbits, to a lesser extent, were active in triggering a regeneration-associated response, whereas substances derived from injured nerves of adult rabbit were not. However, if subsequent to the injury the nerve was implanted with silicone tube containing medium conditioned by neonatal optic nerves, the substances derived from the implanted injured nerve were active. Thus, it appears that the ability of a periaxonal environment to provide triggering substances correlates with axonal growth. Therefore, we named these substances "growth-associated triggering factors" (GATFs). It is suggested that mammalian cells are unable to express a regenerative response after an injury due to the failure of their nonneuronal cells to produce regeneration-triggering substances. This disability may be circumvented by an appropriate implantation procedure.

Aging↗
PubMed1984

Pterygium and beta irradiation.

The results of the combined use of Beta Irradiation, topical Thio-Tepa and dexamethasone in the post-operative treatment of pterygium in 169 patients (213 eyes) are reported. The recurrence rate has been evaluated statistically only in eyes with true pterygia, and for this purpose the material has been divided into 3 groups: group 1 includes all the bilateral cases who either had both eyes treated with Beta therapy or not, group 2 includes all the unilateral cases, and group 3 is made up of the total number of eyes operated. In the group comprising the bilateral cases, the recurrence rate was 2/60 in the eyes treated with Beta rays and 4/18 in the non-treated ones (P less than 0.10). In the group comprising the unilateral cases, the recurrence rate was 8/73 in the Beta rays treated eyes and 18/41 in the non-treated ones (P less than 0.025). When the total number of eyes was considered, the recurrence rate was 10/135 in the eyes treated with Beta rays and 22/61 in the non-treated ones (P less than 0.05). The difference in the recurrence rate between the eyes submitted to Beta therapy and those not submitted is considered statistically significant.

Dexamethasone↗
PubMed1984

Spinal fluid lymphocytes responsive to autologous and allogeneic cells in multiple sclerosis and control individuals.

Spinal fluid lymphocytes from multiple sclerosis (MS) patients and controls were stimulated with either autologous non-T cells or with allogeneic non-T cells followed by stimulation with autologous non-T lymphocytes. Cells responding to these stimuli were cloned and their proliferative responses to autologous and allogeneic MS and normal non-T cells were measured. Large numbers of clones with specific patterns of reaction to both autologous and allogeneic cells were obtained from lymphocytes in MS cerebrospinal fluid (CSF), but only occasionally from cells in control CSF. Patterns of responses among clones from a particular CSF were similar and often identical, which suggested that cells in MS CSF were relatively restricted in their specificities. Surface antigen phenotyping of the clones showed them to be predominantly OKT4+, with 13% OKT8+ and 11% OKT4+8+. Peripheral T cells that were stimulated and cultured in parallel with CSF cells were different in that they usually did not give rise to as many clones nor were their patterns of response similar. Many CSF clones were heteroclitic, that is they responded to particular allogeneic cells but not autologous cells. Lymphocytes in MS CSF thus appear to represent a selected population of cells with a high frequency of responsiveness to autologous and allogeneic antigens. Such responses may be evidence for immune regulation within the central nervous system or could represent responses to altered-self antigens.

Adolescent↗
PubMed1983

Regulation of mRNA levels for microtubule proteins during nerve regeneration.

The molecular regulation of tubulin synthesis was investigated in the regenerating goldfish retina. Previous in vivo studies pointed to an increase in tubulin synthesis in the retina during regeneration of the injured goldfish optic nerve. Using labeled cDNA probes, we showed that this increase occurs as a result of enhanced tubulin mRNA levels. Analysis of labeled in vivo products revealed enhanced beta 2-tubulin synthesis accompanied by an increase in the level of the low-Mr microtubule-associated proteins identified as TAU factors. The results are discussed with respect to the possible involvement of these proteins in the process of nerve regeneration.

Animals↗
PubMed1983

Down's syndrome in adults: brain metabolism.

The cerebral metabolic rate for glucose, as measured with positron emission tomography and fluorine-18-labeled 2-deoxy-D-glucose, was significantly higher in four healthy young subjects with trisomy 21 syndrome (Down's syndrome) than the mean rate in healthy young controls. The rate of cerebral glucose utilization in the frontal lobe of a 51-year-old subject with Down's syndrome was significantly lower than the rate in the young subjects with this syndrome, but approximated the rate in middle-aged controls. Thus glucose utilization by the brain appears to be excessive in young adults with Down's syndrome but may decline with age in some brain regions.

Adult↗
PubMed1983

Inhibition of non-neuronal cell proliferation in the goldfish visual pathway affects the regenerative capacity of the retina.

Proliferating cells associated with the visual pathway were found in the present study to affect the regenerative capacity of the goldfish retina following optic nerve injury. The contribution of these cells to the process of regeneration was investigated in the goldfish visual system by reducing their proliferation in the optic tract and tecta, using X-irradiation. The regenerative ability of the retina was then evaluated by the following parameters: sprouting from retinal explants, protein synthesis in the retina and accumulation of radiolabeled transported components in the tectum. X-irradiation of the visual system at an early stage of the regeneration process had a promoting effect whereas irradiation at a later stage resulted in a reduced capacity to regenerate. The results are discussed with respect to the possibility that proliferating cells, possibly glia, exert two contradictory contributions: an inhibitory effect at the site of injury, whereas distal to it, a supportive, perhaps trophic effect.

Animals↗
PubMed1983

Genetic mapping of antigenic determinants on a membrane protein.

The antigenic determinants recognized by two monoclonal antibodies were mapped on LamB, an outer membrane protein of Escherichia coli. The procedure consisted of performing immunoprecipitation experiments with extracts of strains which produced truncated fragments of LamB, either in a free form (deletion and nonsense mutants) or fused to another polypeptide (malK-lamB and lamB-lacZ fusion strains). The conclusion is that the two antigenic determinants are located within 70 residues from the COOH-terminal end of LamB, which contains a total of 421 amino acids. Since these two antigenic sites were previously demonstrated to be exposed at the cell surface, it follows that a COOH-terminal portion of LamB must be located on the outer surface of the outer membrane.

ATP-Binding Cassette Transporters↗
PubMed1983

Use of deletions created in vitro to map transcriptional regulatory signals in the malA region of Escherichia coli.

The malA region of Escherichia coli contains one of the three maltose operons, namely malPQ, and the positive regulatory gene, malT. Gene malT and the malPQ operon are transcribed in opposite directions, in a divergent manner. The distance separating the transcription start-points in the two directions was previously shown to be 513 base-pairs. We are now presenting a deletion analysis of this unexpectedly long intergenic region. Two sets of deletions were created in vitro, by using exonuclease BAL31. One set comprised deletions centered on a HincII restriction site located in the malPQ promoter, and extending towards gene malT. The other set was centered on an EcoRI site, which had been introduced close to the beginning of the malT cistron, and extended towards gene malP. These deletions, initially created on plasmids, were transferred onto the bacterial chromosome. By studying the phenotype resulting from the presence of these deletions, we concluded that: (1) all of the DNA sequences required for expression of malT and malPQ are within 100 base-pairs of the respective transcription start-points for these genes; (2) a sequence located more than 120 base-pairs upstream from the malT transcription start-point plays a role in limiting malT expression; and (3) a remaining DNA segment, 150 to 300 base-pairs in length, and centrally located in the inter-promoter region, seems to play no role in the expression of malT or malPQ.

Base Sequence↗
PubMed1983

Normal and anomalous potential responses due to K+ changes in bullfrog antrum.

The effect of changing the K+ concentration in the bathing media was studied in the bullfrog antrum. Usually increasing K+ on the nutrient side in standard Cl- -containing and Cl- -free solutions decreased the transmucosal potential difference (nutrient became more negative) - a normal effect. Similar results were obtained on the secretory side. Moreover, for K+ changes on the nutrient side in Cl- media, a plot of magnitude of delta V vs. log [K+] was linear for [K+] greater than 20 mM with slope of 27 mV per 10-fold change in [K+]. However, after bathing the mucosa in Cl- media with zero K+ for about 20 min, elevating the nutrient [K+] to 4 mM increased the potential difference (V) by 4.8 mV in 5 min and repeating the same sequence increased V by 6.9 mV in 5 min - both anomalous effects. Beyond 20 mM K+ the response was normal. In SO2-4 media, an anomalous potential difference of about 1 mV was obtained for changes from 0 to 3 or 6 mM nutrient K+. Ouabain (1 X 10(-3) M) in the nutrient solution abolished the anomalous response in Cl- and SO2-4 media. The normal response is attributed to passive, conductance pathways and the anomalous response because of the effect of ouabain, to a (Na+ + K+)-ATPase pump on the nutrient-facing membrane in which more Na+ than K+ ions are transported per cycle.

Animals↗
PubMed1983

Efficacy of oral and systemic antibiotic prophylaxis in colorectal operations.

A cooperative Veterans Administration study of the septic complication rate during large-bowel surgery was undertaken in two groups of patients. The first group received oral neomycin and erythromycin base plus parenteral placebo; the second, the oral antibiotics plus parenteral cephalothin sodium. During a five-year period, 1,128 patients were studied. The overall septic complication rate was 7.8% in patients receiving only oral antibiotics, and 5.7% in patients receiving both oral and parenteral antibiotics. This difference was not significant. The only significant finding was a greater incidence of fever of unknown origin in patients receiving only oral antibiotics. None of those patients were treated with additional antibiotics, and all fevers cleared spontaneously. There seems to be no discernible benefit from adding parenteral antibiotic prophylaxis when performing elective colon surgery if appropriate mechanical cleansing and oral neomycin and erythromycin therapy are employed.

Administration, Oral↗
PubMed1983

Simultaneous occurrence of mycosis fungoides and Hodgkin disease: clinical and histologic correlations in three cases with ultrastructural studies in two.

We present three patients who manifested both Hodgkin disease and mycosis fungoides. Ages ranged from 39 to 66 and two were male. Skin lesions were present from 3 to 40 years before the diagnosis of Hodgkin disease. In all cases, mycosis fungoides was confirmed histologically by skin biopsy; the clinical course of the mycosis fungoides was indolent in all cases. Hodgkin disease was confirmed histologically in three, and confirmed by electron microscopy in two. All three patients responded to appropriate treatment for Hodgkin disease and are alive and well at the present time.

Adult↗
PubMed1983

Evidence for a coupling of synthesis and export of an outer membrane protein in Escherichia coli.

We describe a lesion, lamB701-708, affecting the hydrophilic portion of the lambda receptor signal sequence. The C to A transversion of the sixth codon of the signal sequence changes a positively charged arginine to a neutral serine. The phenotype conferred by this alteration is unique among previously described signal sequence mutations. The results suggest an essential role for the charged amino acids of the hydrophilic segment in the initial interaction between a nascent secreted protein and a membrane export site. The results further suggest that synthesis of lambda receptor is coupled to its export.

Artificial Gene Fusion↗