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Biomedical subjects

J Feldman

Publications and source records attributed to J Feldman.

At least 235 records · Page 13Linked to original sources
PubMed1982

A study of lithium carbonate use in a health maintenance organization.

The Harvard Community Health Plan, a Boston-based health maintenance organization, evaluated the use of lithium carbonate in its mental health department. Criteria were developed for four categories of care: prerequisite workup, initialization of therapy, maintenance of therapy, and management of side effects. Patient records were evaluated for a retrospective control period, an experimental period in which educational interventions (education seminars and reminder notices) were provided to practitioners, and a postexperimental period in which interventions were discontinued. Practitioners' performance improved during the experimental period but declined to control-period levels during the postexperimental period.

Adult↗
PubMed1982

Analytical methods for microbiology in the next decade.

As microbiologists develop and modify methods and turn to automated equipment to decrease analysis time, the precision and accuracy of the methods must be ensured through collaborative study. Rapid, validated methods are needed in many areas. Sterility testing and the use of biological indicators are among subjects of interest to FDA and industry. These groups are also studying particulate analysis. The limulus amebocyte lysate test is being considered for use in detecting endotoxins in drugs and medical devices, in diagnosing illness, and in assessing the microbiological quality of foods and water. Reliable methods are needed for detecting viruses in foods to assure a safe food supply. Studies are needed on the Vibrionaceae to better understand the mechanisms of invasiveness and host response. Methods must also be developed to study pathogens in the water and food supply.

Drug Contamination↗
PubMed1981

The central hypotensive action of baclofen in the anaesthetized cat.

In the pentobarbital-anaesthetized cat, the intracerebroventricular administration of 20 microgram/kg d,1-baclofen led to marked hypotension and bradycardia, whereas the same dose of d-baclofen (i.c.v.) had no cardiovascular effect. When the drug was prevented from reaching the brain stem structures by collecting perfusate through a catheter lodged in the Aqueduct of Sylvius, the efficacy of d,1-baclofen was increased. Bicuculline did not antagonize the central cardiovascular effects of d,1-baclofen at doses which inhibit the cardiovascular effects of GABA agonists. However, both glutamic acid and kainic acid prevented and reversed the central hypotension and bradycardia produced by d,1-baclofen. These effects of baclofen may therefore be mediated by a selective inhibition of the release of the excitatory neurotransmitter, glutamate, within forebrain structures involved in central cardiovascular regulation.

Anesthesia↗
PubMed1981

Survival following breast cancer surgery in the elderly.

A retrospective analysis was performed on a series of 780 patients with breast cancer who underwent surgery, with emphasis on survival in the 138 patients over 70 years of age (elderly group). Absolute survival rates were determined using life table methods. Relative survival figures were derived from absolute figures by adjusting for expected longevity in each group. Patients over 70 years of age had overall 5 and 10 year absolute survival rates of 54% and 41%, respectively, which did not differ significantly from survival rates of younger patients. Relative five-year survival rates for the elderly were actually higher than those of younger patients, being 90% for those with local disease and 65% for those with regional disease. Survival in the elderly was comparable to that of younger patients, irrespective of race, type of surgery, histology or tumor size. These findings support the conclusion that there is little justification for avoiding conventional operative treatment in elderly patients with breast cancer solely on the basis of advanced age.

Age Factors↗
PubMed1981

The nucleus reticularis lateralis: a region highly sensitive to clonidine.

Slow bilateral microinjections of a low dose of clonidine (75 ng/kg) in the cat's nucleus reticularis lateralis (NRL) lead to significant hypotension and bradycardia. This finding confirms the existence of a ventromedullary highly sensitive site of action of clonidine. It is suggested that clonidine inhibits some vasopressive and cardioacceleratory structures within the NRL region.

Animals↗
PubMed1981

Biofeedback of accommodation to reduce functional myopia.

Functional myopia may be defined as the refractive condition of the eye due to spasm of the ciliary muscle. As a result of the ciliary muscle spasm, the crystalline lens becomes more convex, creating a myopic refractive condition. The normal increase and decrease in the refractive power of the crystalline lens is know as accommodation and is controlled by the autonomic nervous system innervation to the ciliary muscle. Previous studies have reported that voluntary control of accommodation is possible by biofeedback training (Cornsweet & Crane, 1973; Randle, 1970). The present research investigated the application of biofeedback control of accommodation to reduce functional myopia. A double-reversal, multiple-baseline design was used to conduct the experiment. The results revealed that the three adult male subjects achieved the preset criterion, a 1/2-diopter reduction from initial baseline to a subsequent baseline. Further analysis of the data revealed even greater changes between initial baseline and feedback periods. Although generalization to a nonexperimental environment was not trained, each subject showed a reduction in myopia and an increase in visual acuity. The results of the experiment clearly demonstrated that functional myopia is subject to voluntary control.

Accommodation, Ocular↗
PubMed1981

Reliability of fixation disparity curves.

Fixation disparity curves were recorded in three normal subjects once per week over a period of 10 weeks. Results indicate that measurements of fixation disparity are reliable within limited ranges of forced convergence and forced divergence. Increases in the demand to maintain fusion lead to increases in observed variability of fixation disparity. It is suggested that variability of fixation disparity might be related to the ease with which the two eyes are used as a team.

Adult↗
PubMed1981

The ventromedullary hypotensive effect of muscimol in the anaesthetized cat.

Muscimol, a rigid analogue of GABA, was injected into the CNS of urethane-anaesthetized, normotensive cats. Bilateral microinjections of a small dose of muscimol (100 ng/kg, 0.5 microliter on each side) in the nucleus reticularis lateralis (NRL) induced hypotension. The marked fall in blood pressure obtained by injecting 1 microgram/kg of muscimol unilaterally into the NRL is completely reversed by subsequent local administration of bicuculline (5 microgram/kg, 0.5 microliter), a specific GABA antagonist. These data confirm that a GABAergic inhibitory system modulates the pressor tonic structures localized in the region of the NRL and that the anteroventral part of the medulla oblongata includes a trigger zone for the hypotensive action of muscimol.

Anesthesia↗
PubMed1981

Behavior modification in vision training: facilitating prerequisite behaviors and visual skills.

Nine studies are presented illustrating how operant conditioning techniques can be used to facilitate the acquisition of task-relevant skills of young vision training patients. Four cases describe how behaviors considered prerequisite for visual skill training can be improved; task attention and motivation. Five cases show how special operant learning procedures, directly applied to visual skill performance, can facilitate the acquisition of such skills. It was suggested that all attempts at effective visual training recognize the role of scientifically based principles of learning and motivation in improving visual skills.

Behavior Therapy↗
PubMed1981

The influence of age upon the survival of adult patients with carcinoma of the colon.

Five hundred adult patients with carcinoma of colon were studied to determine the relationship between age and prognosis. Regardless of the stage of disease or curative or palliative operation, younger patients had a better prognosis. Deaths after three years postresection were usually due to associated disease, which probably accounts for the poorer prognosis in the older patient. The poor prognosis frequently reported in young patients with carcinoma of the colon usually applies to those less than 25 years of age who may have a different form of the disease.

Adult↗
PubMed1981

Central cardiovascular effects of taurine: comparison with homotaurine and muscimol.

The central cardiovascular effects of taurine were compared with those of homotaurine and muscimol. The drugs were injected i.c.v. in cumulative doses into pentobarbital-anesthetized cats. Muscimol (0.1-30 microgram/kg) produced dose-dependent hypotension and bradycardia, with a maximum effect of 70 +/- 5 mm Hg and 75 +/- 5 beats/min, respectively. Homotaurine led to a dose-related fall in blood pressure and heart rate; maximum effects were obtained with 300 microgram/kg and averaged 55 +/- 3 mm Hg and 73 +/- 3 beats/min. For both drugs, the dose-response curves were shifted to the right by pretreatment with 10 microgram/kg of bicuculline i.c.v. This antagonism confirms that the central cardiovascular effects of muscimol and homotaurine are mediated by a stimulation of gamma-aminobutyric acid receptors. Taurine produced dose-related hypotension and bradycardia. The depressive effects of taurine started at a dose of 10 microgram/kg; at a dose of 1000 microgram/kg, the maximum effects observed were a 55 +/- 7 mm Hg hypotension and a 53 +/- 8 beats/min bradycardia. These effects were not affected by bicuculline pretreatment, but strychnine (i.c.v) prevented the effects of taurine. These findings indicate that glycine-type receptors may be involved in the taurine effects rather than gamma-aminobutyric acid type receptors. However, these results do not exclude the involvement of taurine-type receptors for which the specific antagonists is not yet available.

Animals↗
PubMed1980

Medullary cardiovascular effects of tetrodotoxin in anaesthetized cats.

Tetrodotoxin injected in the cat nucleus tracus solitarii produced hypertension without bradycardia, whereas in the nucleus reticularis lateralis it led to hypotension and bradycardia. Tetrodotoxin acts by blocking neuronal activity; it is a useful tool for studying the central organization of cardiovascular regulation. The present data confirm that the nucleus reticularis lateralis is a vasopressive centre.

Anesthesia↗
PubMed1980

Ultrastructure of Merkel cells in the hard palate of the squirrel monkey (Saimiri sciureus).

The distribution and ultrastructure of Merkel cells in the hard palate was investigated in the squirrel monkey (Saimiri sciureus) after fixation by vascular perfusion. Merkel cells were clustered at the base of the epithelial rete pegs of the hard palate. They were characterized by concentrations of dense-cored granules and closely associated intraepithelial nerve endings. Numerous spiny processes extending from the Merkel cell were intercalated with adjacent keratinocytes, probably serving to detect and amplify movement of adjacent cells. These spiny processes contained a rigid core of parallel microfilaments which were interrelated with cytoplasmic filament bundles located beneath the cell membrane. Transitional cells containing dense-cored granules and well developed tonofibrils appear to be related to both Merkel cells and keratinocytes. The findings of this study suggest that Merkel cells are highly adapted for detection of movement in adjacent keratinocytes, as well as movement of the epithelium with respect to the underlying connective tissue.

Animals↗
PubMed1980

Transplantation of insulinoma into the diabetic Syrian hamster.

Syrian hamsters were rendered diabetic with intraperitoneal streptozotocin and were maintained in the diabetic state for a minimum of 14 days. A hamster islet cell tumor was transplanted subcutaneously with a prompt return of water intake (38 +/- 9.1 ml/day to 7.1 +/- 2.2 ml/day, mean +/- SD), urine glucose (4.8 +/- 0.84 g/day to less than 250 mg/day), urine output (37.4 +/- 10.9 ml/day to 7.6 +/- 2.1 ml/day), blood glucose (297 +/- 31.9 mg/dl to 87.6 +/- 28 mg/dl), and weight gain (1.0 to 0.8 g/day) to normal control levels. Histologic examination of the engrafted tumors revealed a well encapsulated tumor with no evidence of metastatic disease. The transplanted insulinomas maintained well differentiated histologic features without evidence of necrosis. Immunopathologic studies failed to reveal any evidence of either humoral or cell mediated immunity directed toward the allograft. Each animal was successfully transplanted with a 1 mm tumor explant. A single rodent tumor donor provided adequate material for engraftment for five recipients. The transplanted insulinomas maintained full functional and enzymatic capabilities. Similar studies utilizing the hamster insulinoma engrafted into the athymic nude mouse showed amelioration of the same diabetic symptomatology. Many of the technical difficulties encountered with whole organ and isolated islet transplantation encourages development of a more practical model. These experimental results suggest an alternative method for supplying the diabetic with an endogenous insulin source.

Adenoma, Islet Cell↗
PubMed1980

Operant conditioning of fusional convergence ranges using random dot stereograms.

In Experiment 1, four 6- to 10-year-old strabismus patients, who had failed to improve convergence ranges using traditional vision training techniques, were given convergence training using random dot stereograms (RDS). An integral part of the RDS training procedure was the incorporation of an operant conditioning procedure providing for response-contingent positive reinforcement, immediate feedback, and preprogrammed systematic changes in convergence demand during discrimination learning. Findings indicated that operant RDS convergence training produced a significant increase in convergence ranges which transferred readily to vectogram tasks and resulted in a change from exotropia to exophoria for at least one patient. In Experiment 2, it was shown that improved convergence ability was a direct result of exposure to RDS of increasing convergence demand. It was concluded that young, uncooperative, language-deficient, or inattentive patients show improved convergence ranges when such training incorporates proper stimuli and the basic principles of learning and motivation into its training regimen.

Accommodation, Ocular↗
PubMed1980

Immunological consequences of transplanting rat insulinomas.

We investigated the genetics of transplanting a NEDH rat insulinoma in various donor-recipient combinations. The insulinoma survived indefinitely when it was transplanted in the NEDH strain. Mean survival times of 8.6 +/- 1.2 and 3.3 +/- 1.0 days were recorded in allogeneic and xenogeneic combinations, respectively. No prolongation of mean survival time was found when the rat insulinoma was first passed through the athymic nude mouse and then transplanted as either an allograft or xenograft. The findings of the major histocompatibility antigen (Ag-B7) on the original insulinoma and the tumor that had been passed through the nude mouse demonstrates no demonstrable loss of transplantation antigens during passage.

Adenoma, Islet Cell↗