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Biomedical subjects

M S Silverman

Publications and source records attributed to M S Silverman.

14 recordsLinked to original sources
PubMed1978

Changes in latency and duration of neural responding following developmental auditory deprivation.

The initial latency of spikes evoked by click stimulation and the duration over which spiking occurred were observed in the inferior colliculi of rats. One ear of these animals had been deprived of early auditory stimulation by ligation of the external meatus. Clicks presented to the normally experienced ears evoked spikes in the opposite colliculus with latencies that depended on the characteristic frequency of the unit. Low-frequency (less than 5 kHz) units had latencies from 6-10 msec. Latencies declined to 3-4 msec for high frequency (greater than 20 kHz) units. After an ear had been deprived of sound from 10 days after birth, response latencies of units in the opposite colliculus with characteristic frequencies below about 10 kHz were comparable to controls, but most units above 10 kHz had latencies 2-3 times control latencies. Spike activity evoked in these units did not continue as long as that for most comparable control units. Ears sound deprived for an equal period from 60 days after birth also had changes in latencies and response durations, but these were much less than in the developmentally deprived. Latencies of gross potentials at the auditory nerve were not affected by early deprivation, indicating a central origin for the latency changes.

Acoustic Stimulation↗
PubMed1978

The effects of human saliva on the hemolytic activity of complement.

Human saliva was tested for the presence of factors that affect the complement system. Parotid saliva and salivary fractions were incubated at 37 C with human serum as a source of complement. Samples removed from the mixtures within the first 15 minutes had higher levels of whole hemolytic complement activity than did appropriate controls. The final ionic strength of the saliva-serum mixtures was critical to the hemolytic activity of complement. After 60 minutes all serum-saliva mixtures had lower levels of hemolytic activity than did serum-buffer controls. With regard to whole saliva, the salivary sediment was found to be strongly complement-reactive.

Animals↗
PubMed1977

Effects of lesioning the dorsal and intermediate acoustic striae on binaural interaction at the inferior colliculus.

Contralateral clicks normally activate units in the inferior colliculus of rats. Ipsilateral clicks usually inhibit this activity when their intensity just exceeds the contralateral intensity. When the contralateral dorsal and intermediate acoustic striae are lesioned as they pass over the restiform body, ipsilateral clicks inhibit even if they are substantially less intense than contralateral clicks. Contralateral click thresholds for unit activation are elevated by about 10 dB, but this shift in sensitivity cannot account for the marked advantage gained by the ipsilateral inhibitory input. These findings suggest that one or both of these pathways contributes heavily to binaural interaction at the inferior colliculus.

Animals↗
PubMed1977

Catalase in salivary gland striated and excretory duct cells. II. phi body: an ellipsoidal peroxisomal organelle with crystalloid axial projections.

A new distinctive and unique peroxisomal organelle with a spindle shape has been observed in luminal epithelial cells of striated and excretory ducts of mouse salivary glands. Light microscopic studies indicate it has an ellipsoidal centre from which catalase-positive filamentous or rod-like processes protrude along its major axis; hence, it is called a phi body. A role for this specialized peroxisome in the formation of nearby free filaments and rods is suggested by the frequent observation of segmentation of its axial processes. Complementary ultrastructural studies of osmium-fixed preparations show that the deformation to an oval shape results from the pressure of the extruding crystalloid coincident with the major axis of the ellipsoidal body. The size range and conformation of phi body axial processes are comparable to those of free catalase-positive rods and filaments observed in the same cells. The periodic substructure of the crystalloid in the phi body core is identical with that of nearby cytoplasmic rods. These observations are consistent with the view that the rods and filaments observed free in the cytoplasm are formed by extrusion from the crystalloid core of the phi body. phi Bodies could also be responsible for the Aver rods of leukemic leukocytes.

Animals↗
PubMed1977

Detection of functional complement components in gingival crevicular fluid from humans with periodontal diseases.

Crevicular fluid was collected from patients with periodontitis by a capillary tube procedure. Complement component activities were determined by functional assay systems, with human complement, and partially purified human first complement component (C1) as controls. The complement-fixing properties of the dental plaque of each patient were also examined C1 activity in the crevicular fluid of all patients was approximately 1/8 of whole serum C1 and diminished rapidly with time after collection. There was no significant relationship between C1 concentration and crevicular fluid flow rate. Hemolytic activity of whole complement was also invariable detected when sufficient amounts (8 micronl) of crevicular fluid could be obtained. Dental plaque was found to fix C1. A role for crevicular complement in inflammatory periodontal disease is suggested.

Complement C1↗
PubMed1977

Alveolar bone loss in thymectomized golden hamsters.

Fifty-six neonatally thymectomized and 41 neonatally sham-operated female golden hamsters (Mesocricetus auratus) were divided into 2 groups, one inoculated with Actinomyces (N16) and the other not inoculated. All animals were raised and maintained on a high sucrose, soft diet (Diet 2000) and water, ad libitum. White blood cell counts, differentials and total lymphocyte counts were determined at 4 to 5 weeks of age. The rejection of albino hamster skin grafts and the hemagglutination response to sheep red blood cells (SRBC) were used to determine inhibition of T lymphocyte function. Evaluation of alveolar bone loss at the end of 160 days indicated that the thymectomized animals with a significant depression of the hemagglutination response to SRBC and a lack of skin graft rejections had a significantly higher bone loss than sham-operated animals. This suggests that the cellular immune response plays a role in the periodontal syndrome in hamsters. Further investigation is necessary to establish how significant this role is in relationship to the numerous other factors that are present. These data suggest that the role of the cellular immune response in the hamster periodontium may be protective rather than destructive. The role of Actinomyces (N16) in the development of bone loss was not significant.

Actinomyces↗
PubMed1976

Binding of triton X-100 to diphtheria toxin, crossreacting material 45, and their fragments.

Binding of the nonionic detergent [3H]Triton X-100 by diphtheria toxin, by the nontoxic serologically related protein crossreacting material (CRM) 45, and by their respective A and B fragments has been studied. If first denatured in 0.1% sodium dodecyl sulfate, all of the proteins with the exception of fragment A bind increasing amounts of Triton X-100, reaching a maximum of more than 40 mol bound per mol of protein when the detergent concentration exceeds its critical micelle concentration. No measurable amount of Triton X-100 is bound by native toxin or its A fragment of any concentration of the detergent. Undenatured CRM45 or its B45 fragment, on the other hand, readily became inserted into Triton X-100 micelles when the detergent reaches its critical micelle concentration. The results show that the toxin molecule contains a hydrophobic domain located on the portion of the B fragment that is linked to A. This region is masked in native toxin. Based on these findings, a model is proposed to describe how fragment B facilitates the transport of the enzymically active hydrophilic fragment A across the plasma membrane to reach the cytoplasm.

Binding Sites↗
PubMedDate not supplied

Failure of rabbit anti-Streptococcus mutans serum to penetrate in vitro plaque.

An indirect fluorescent antibody technique indicated that specific antiserums did not penetrate in vitro plaque formed by Streptococcus mutans. Specific reactions did occur between the antiserums and antigens in the surface layers of plaque globules. Measurements of plaque diameters indicated that the serums exerted a nonspecific effect of enhancing plaque growth.

Animals↗