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Biomedical subjects

A Prasad

Publications and source records attributed to A Prasad.

At least 127 records · Page 7Linked to original sources
PubMed1994

Neurons derived from embryonal carcinoma (P19) cells express multiple GABAA receptor subunits and fully functional GABAA receptors.

The embryonal carcinoma (EC) cell line P19 can be induced to differentiate into neurons and glia by treatment with retinoic acid. Neuronal cells derived from P19 stem cells were found to express messenger RNAs for alpha, beta, and gamma 2 subunits of the GABAA receptor-chloride channel complex. Whole-cell voltage-clamp recording in differentiated P19 cells revealed that these cells possess GABA receptor-activated chloride currents which are blocked by bicuculline and potentiated by flurazepam. P19 EC cells thus represent a stable neuronal cell line which expresses functional GABAA receptors with all of the characteristics of native GABAA receptors.

Animals↗
PubMed1994

Individual differences in the macronutrient preference profile of outbred rats: implications for nutritional, metabolic, and pharmacologic studies.

While screening outbred male Holtzman Sprague-Dawley rats for their macronutrient (protein, carbohydrate, and fat) preferences, we noticed substantial group-to-group variation in the preference profile. This led us to analyze preference data on two hundred and seventy rats collected over a three-year period to determine whether preferences could be predicted. The results led us to conclude that observed variations in macronutrient preference profiles may be secondary to genetic heterogeneity in the outbred population. We have also shown that the outcome of the pharmacologic effects of two agents (insulin and enterostatin) on appetitive behavior will vary from animal to animal within a single group. Accordingly, researchers must be aware that the breeding history of the laboratory animal is a major factor in the outcome of the experiment and interpretation of the findings.

Animal Nutritional Physiological Phenomena↗
PubMed1994

A randomised trial of routine versus selective counselling in perinatal bereavement from congenital disease.

OBJECTIVE: To find out whether routine counselling improves psychological wellbeing after bereavement for fetal abnormality. DESIGN: A randomised trial among bereaved couples who did not demonstrate any unexpected strain or psychopathology after bereavement. SETTING: St. James's University Hospital, Leeds. SUBJECTS: Fifty-seven couples. INTERVENTIONS: Independent counselling by an experienced psychotherapist. MAIN OUTCOME MEASURES: Self-administered questionnaires measuring grief, anxiety and depression and a structured psychological interview 16 to 20 months after the loss. Anniversaries of a death or expected birth date were avoided. RESULTS: There were no differences in outcome between women randomised to the study group or randomised to the control group with respect to grief, anxiety, depression or the results of the structured overview. Among those in the randomised study group, women who attended for counselling had a much better outcome than women who defaulted from counselling. Overall, women who underwent termination of pregnancy did slightly worse than those who had experienced stillbirth or neonatal death. On an informal basis, the clinician concerned believes that he was better able to help bereaved couples as a result of feedback and criticism from the independent counsellor. CONCLUSIONS: (1) The hypothesis that all couples should have independent counselling after prenatal loss for congenital abnormality is unproven, but it is likely that clinicians can benefit from feedback from a counsellor; (2) it is possible that termination of pregnancy is more psychopathogenic than other forms of fetal loss; (3) people who attend for their counselling sessions are probably inherently better able to adjust to bereavement; (4) trials of psychological intervention are feasible, but follow up is either difficult to achieve or expensive.

Abortion, Spontaneous↗
PubMed1994

Solitary intracranial plasmacytoma of the skull base.

Two cases of extradural solitary plasmacytoma (SIP) with infiltration of the dura, destruction of the skull base, multiple cranial nerve palsies and proptosis are presented. The cases were treated aggressively with surgery and radiotherapy and showed no signs of progressing to multiple myeloma after 15 months and four and a half years respectively.

Adult↗
PubMed1993

Regulation of dietary fat preference: establishing a reproducible profile of dietary fat preference in rats.

The mechanism(s) underlying preference for individual macronutrients (particularly fat) in diet are poorly understood. The greatest obstacle in designing experiments to define neurochemical determinants of fat preference lies in our ability to clearly identify animals' macronutrient preference (MP) profile. To this end, we have defined the role of several variables and suggested ways to design better studies to examine the mechanism of macronutrient preference. The results of these studies show that the paradigm used for MP analysis, genetics and age of the animal could clearly affect the MP profile.

Aging↗
PubMed1992

Ethanol modulation of GABA receptor-activated Cl- currents in neurons of the chick, rat and mouse central nervous system.

Modulation of gamma-aminobutyric acidA (GABAA) receptor function by drugs such as ethanol may depend on the genetic heterogeneity of GABAA receptor subunits, which vary across species and cell types. For this reason, the effects of ethanol on gamma-aminobutyric acid receptor-activated chloride currents (IGABA) were examined using whole-cell voltage-clamp recordings in primary cultures of neurons obtained from different species (chick, mouse and rat) and from different brain regions (cerebral cortex, hippocampus, cerebellum and spinal cord), and in acutely dissociated neurons from rat neocortical slices. Low concentrations (1-50 mM) of ethanol produced an enhancement of IGABA in some cells from each brain region examined. In cells obtained from the rat and chick cerebral cortex, 40-58% of cells exhibited an ethanol-sensitive IGABA. Moreover, a statistically significant variation in the response to ethanol was found in rat cortical neurons obtained from different litters. In mouse hippocampal neurons, potentiation of IGABA was obtained with ethanol concentrations (1-10 mM) well below those needed to inhibit neuronal responses to N-methyl-D-aspartic acid (30-50 mM), suggesting a differential sensitivity of these two receptor mechanisms to ethanol. Potentiation of IGABA by ethanol was reversed by the benzodiazepine receptor partial inverse agonist RO15-4513 (ethyl 8-azido-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]benzodiazepine - 3-carboxylate), but was not affected by chelation of intracellular calcium. Furthermore, high concentrations of GABA attenuated the ability of ethanol to enhance IGABA. These results are consistent with the hypothesis that ethanol facilitates coupling between receptor binding and chloride channel activation.

Animals↗
PubMed1992

Uncoupling of GABA-benzodiazepine receptors in chick cerebral cortical neurons requires co-activation of both receptor sites.

Primary cultures of chick cerebral cortical neurons were exposed to 1 microM flurazepam in vitro, and the effect of flurazepam on GABA-activated membrane current (IGABA) was examined using whole-cell voltage-clamp recording. Exposure of chick cerebral cortical neurons to flurazepam alone for 3-10 days resulted in a significant decrease in the degree of potentiation of IGABA elicited by 0.5 microM flurazepam. When GABA or nipecotic acid (a GABA uptake blocker) were added with flurazepam during chronic drug exposure, neuronal responses to GABA were significantly less sensitive to modulation by 0.5 microM flurazepam compared to flurazepam treatment alone. Furthermore, this effect was significantly reduced by co-administration of the GABAA receptor antagonist bicuculline. These results suggest that tolerance to benzodiazepines in vitro requires activation of both the GABA and the benzodiazepine binding sites on the GABAA receptor-channel complex.

Animals↗
PubMed1992

Cryptogenic osteomyelitis of the skull and intracerebral abscess.

The authors report a rare case of cryptogenic osteomyelitis of the skull with an intracerebral and a subgaleal abscess. Total excision of the abscess extending from the cortical surface to the lateral ventricle led to ventriculitis and subgaleal cerebrospinal fluid collection. These complications could have been avoided by aspirating the abscess after removing the infected portion of the skull and the epidural granulation tissue. Neurosurgeons preferring to excise such an abscess should leave a small area of capsule at the base in order to avoid having to open the ventricle.

Brain Abscess↗
PubMed1992

Resistance to insulin-induced hyperphagia in fat-preferring rats.

Outbred male Sprague-Dawley rats were screened for their macronutrient (fat, carbohydrate and protein) preference profile and divided into two groups, the low- and high fat-preferring groups each deriving 23% and 72% of its total caloric intake from fat respectively. Subcutaneous administration of bovine insulin (6U/kg) resulted in an increase in total caloric intake in the low, but not the high fat-preferring group. Furthermore, the increased caloric intake in the low fat-preferring group was entirely due to increased carbohydrate consumption. These data suggest a defect in the action of insulin in fat-preferring rats.

Animals↗