Biomedical subjects
Publications and source records attributed to R S Feldman.
The physician who is aware of oral problems can play an essential role in providing comprehensive care for the elderly. The average person 65 years or older visits the physician at least six times a year, but is seen by the dentist about once a year. Because of more frequent contact, the physician has a greater opportunity to identify important dental problems of the geriatric patient.
Collagen production by fibroblasts has been shown to be transformation sensitive and to correlate inversely with tumorigenicity. Therefore, it is of interest to determine if carcinoma cell collagen production is similar to fibroblast collagen production. Since there are few carcinoma model systems available for this study that have cultured cells with increasing tumorigenic potential, a new series of cell lines, referred to as M-cells, were developed from the well-described rat liver epithelial cell line W8, originally established by I. B. Weinstein. The W8 cell line is a N-acetoxy-2-acetylaminofluorene-treated, weakly tumorigenic rat liver cell derived from the parent K16 cell line. The M-cells were serially selected by isolating cell lines from tumors and reinjecting them into animals. Although these M-cells maintain their epithelial characteristics, their overall protein production, their type of collagen, and their ability to form undifferentiated carcinomas in vivo, they progressively exhibit increasing tumorigenic potential, increasing anchorage independence, and decreasing collagen production. The W8 and M-cells maintain decreasing amounts of collagen type I trimer production, which most likely contributes to the decreasing connective tissue stroma observed in their carcinomas. This cell system provides a new model to examine epithelial cell surface and extracellular substrate attachment interactions.
This study tested a behavior-suppressing punishment system and how its activity may be altered by agents known to interrupt or enhance serotonergic (5-HT) transmission. Holtzman male albino rats were tested for shuttle box avoidance acquisition and intertrial responding either 1 or 8 h following daily injection of fenfluramine (FEN) or fluoxetine (FXT). When the drug-test interval was 1 h, a time when both drugs are presumably potentiating 5-HT activity, avoidance acquisition and intertrial responding were impaired. When testing occurred 8 h after drug treatment, a time when 5-HT level are unaltered by FXT and are maximally reduced by FEN, these drugs had no effect on avoidance acquisition, but FEN produced an increase in intertrial responses whereas FXT did not. These results support the proposal of an inhibitory 5-HT system. Furthermore, these data demonstrate that FEN is capable of exerting a biphasic action on intertrial responding and suggest that the time interval between drug administration and behavioral testing is a crucial variable when investigating FEN.
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Oral leukoplakia, a potentially malignant lesion, has been associated with tobacco smoking, but few studies have investigated the influence of different products on lesion prevalence. In the current study 925 healthy male subjects from the Veterans Administration Dental Longitudinal Study were examined for lesion site and prevalence. The participants were grouped according to smoking status: nonsmokers, smokers of cigarettes, cigars, a pipe, cigars plus a pipe, or cigarettes plus another tobacco product. In addition, the amount of product smoked, presence of a removable partial denture, and age were examined to determine their relation to leukoplakia prevalence. The data indicated that cigar smokers had significantly fewer lesions than the other smoker groups and that persons smoking a pipe or a pipe plus cigars had the highest prevalence. Heavy cigarette smokers had significantly more palatal lesions than light to moderate cigarette smokers. While removable partial dentures did not appear to affect lesion prevalence significantly, older smokers, persons of 50 years and above, had a significantly higher prevalence than persons less than 50 years of age.
Using a milk reinforced two-lever operant procedure, rats were trained to discriminate 3 mg/kg chlordiazepoxide (CDP) from saline. Following this, generalization experiments were conducted with the triazolopyridazine CL 218,872, a synthetic non-benzodiazepine (BDZ) ligand for the BDZ receptor. CL 218,872 produced CDP lever selection in a dose related fashion and thus generalized to the standard CDP treatment. However, this generalization was antagonized by the concurrent administration of pentylenetetrazol or amphetamine, but not by strychnine or bicuculline. Also, there was evidence for cross tolerance for a sedative effect between CDP and CL 218,872.
The current cross-sectional investigation was undertaken to determine whether observed losses in masticatory function due to missing teeth impair perceptual estimates of food acceptability. To quantify the effect of impaired masticatory ability, 566 male participants from the Veterans Administration Dental Longitudinal Study were subdivided into three age groups (less than 40 years, 40 to 49 years, and 50 or more years) and three dentition categories (intact, partially compromised, and compromised). Bivariate analysis revealed that dentition status significantly influenced the acceptance modalities of taste, texture, perceived ease of chewing, and frequency of ingestion. Age, per se, had little effect. Significant changes in the acceptance variables were noted only in persons with compromised dentition. These findings suggested that a moderate degree of unreplaced tooth loss had no significant effect on perceptual estimates of food acceptability, and unilateral intact dentition can provide sufficient masticatory performance for maintaining food acceptance.
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This paper presents a review of the literature of various modes of physical therapy available to the podiatrist. Included are superficial and deep heating agents, applications of cold, and massage. Their methods of application, physiological responses, indications, and contraindications are discussed.
The prelinguistic, nonverbal communicative behavior of 40 institutionalized severely and profoundly retarded children and adolescents functioning at various stages of Piaget's sensorimotor period was examined. Five scales of the Uzgiris and Hunt (1975) sensorimotor assessment were used to determine general level of sensorimotor functioning. A standard set of communication elicitation tasks was employed to examine the gestures used to communicate in both imperative and declarative contexts. More competent sensorimotor performance was associated with higher frequency of more sophisticated and symbolic forms of gestural communication, and subjects generally used more complex gestures to communicate in the imperative than in the declarative tasks. Applicability of the results to the design of future language-intervention programs and their implications for general theory concerning the relations between language and cognition and between normal and atypical development were discussed.
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Few comprehensive studies of oral function have been conducted on adult populations. A "Longitudinal and Cross-Sectional Study of Oral Health in Healthy Veterans" was activated at the VA Outpatient Clinic in Boston in 1969; it included general oral and dental examinations as well as tests of masticatory performance and the swallowing threshold. The current investigation involved 863 subjects from the "Dental Study" who had either their natural teeth or a fixed replacement for missing teeth. Masticatory performance as measured by the subject's ability to reduce a test portion of cut carrot by a mandatory number of chewing stroked remained constant for persons with complete or partially compromised natural dentition. Swallowing threshold performance as measured by the particle size acceptable for swallowing remained constant for persons with complete dentition. Tooth loss significantly decreased the swallowing threshold performance and increased the particle size which the subject was willing to swallow. Older subjects increased the number of chewing strokes and the time required for this test, an observation not related to performance as measured by final particle size. Only with compromised dentition, however, did this increased effort result in increased performance.
We have investigated hormonal interactions regulating bone resorption by measuring biochemical and morphological responses of neonatal mouse calvaria in vitro to treatment with 0.1 U/ml parathyroid hormone (PTH) without or with 100 ng/ml human calcitonin (CT). Calvaria were also labeled continuously with 0.5 microCi [3H]thymidine/bone. By 96 h, PTH stimulated the release of calcium (Ca) into the medium to 240% of control, while CT alone stimulated release of Ca to 96% of control. CT in the presence of PTH transiently inhibited the release of Ca up to 24--48 h after its addition. The subsequent loss of responsiveness to CT has been described as escape. Light microscopic analysis showed that PTH treatment markedly increased the number of osteoclast profiles in parallel with the stimulation of Ca release. Ct in the presence of PTH only transiently slowed the increase in osteoclast profiles. Fewer osteoclast profiles were observed in the presence of CT alone than in the control. Autoradiography of PTH-treated bones first showed [3H]thymidine label in osteoclast nuclei at 24 h, which increased markedly by 96 h. In PTH- plus CT-treated calvaria, significantly fewer osteoclast nuclei were labeled even at 96 h. In summary, hormonally induced changes in osteoclast profiles correlated well with changes in the stimulated release of Ca from calvaria. PTH had at least two effects on cell kinetics: 1) an early effect to increase the number of osteoclasts by fusion of preexisting mononuclear osteoclast precursors, and 2) a later effect to increase the fusion of postmitotic mononuclear cells with osteoclasts. In parallel with the observation of escape, CT only transiently inhibited PTH-stimulated osteoclast formation. The transient inhibition by CT of PTH-stimulated resorption can be explained by an early effect on osteoclast precursor cell fusions.
The time course of action of repeated daily doses of chlordiazepoxide (CDP) was examined in mice with septal lesions. Bilateral septal lesions produced changes in both conditioned and unconditioned behavior. These lesions increased rate of operant responding on a VI-40 s schedule and produced hyperreactivity to tactile stimuli. The effects of repeated administration of CDP on these two classes of behavior were observed to follow different time courses. In a dose dependent fashion, CDP first reduced VI response rates in septal mice, but after several daily doses the response rate increased above post-surgical baseline levels. The suppressant effects of CDP on septal hyper-reactivity were quite different. Hyper-reactivity was persistently attenuated by all CDP doses tested during the eight-day drug regimen. The pattern of drug effects suggested that serotonin antagonism was involved in CDP's effects on lesion produced hyper-reactivity.
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Chlordiazepoxide, which blocks serotonin turnover, increased food intake; and fluoxetine, a serotonin agonist, decreased food intake. Administration of combinations of the two drugs showed an antagonistic dose-dependent relationship, implicating a satiety of hunger mechanims which is mediated by serotonin.
The effects of inspiration of low O2 and/or high CO2 gas mixtures on relative tissue PO2 and perfusion of brain and muscle were studied in 60 pentobarbital-anesthetized spontaneously respiring rats. These animals were studied in intact condition, after administration of phenoxybenzamine hydrochloride, 2 mg/kg, or after bilateral denervation of their carotid bodies. In the intact rats, the relative tissue PO2 ratio of biceps brachii to cerebral white matter always decreased after exposure to the above gas mixtures. This indicated a better maintenance of O2 supply to demand in the brain than in muscle. After either carotid denervation or alpha adrenergic blockade, this change in the ratio was no longer significant. Further, cerebral blood flow responses to these gas mixtures were attenuated (avg + 5.3%) compared to previous work in intact rats. It is concluded that the brain is best protected against hypoxia and/or hypercapnia when the carotid chemoreflex is intact.