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Biomedical subjects

L M Singh

Publications and source records attributed to L M Singh.

At least 19 recordsLinked to original sources
PubMed1999

An automated aequorin luminescence-based functional calcium assay for G-protein-coupled receptors.

We describe in detail an automated and highly sensitive functional assay for calcium-coupled receptors (those receptors whose activation results in an increase in intracellular calcium levels) utilizing coelenterazine-charged aequorin as a probe for intracellular calcium levels ([Ca(2+)](i)). The assay was originally established to investigate Galpha(q)-coupled prostanoid receptors, which are members of the G-protein-coupled receptor (GPCR) superfamily, signaling through elevation of [Ca(2+)](i), initially focusing on the human EP(1) prostanoid receptor (hEP(1)). The parental human embryonic kidney cell line 293-AEQ17, developed by Button and Brownstein (Cell Calcium 14, 663-671, 1993), constitutively expresses apoaequorin and was used to develop a clonal cell line which stably coexpresses hEP(1). This cell line was used to optimize assay parameters in order to maximize accuracy and throughput in an automated 96-well format with the result that each 96-well plate can be completed in 70 min. Use of this flexible system will greatly simplify the functional analysis of GPCRs and other receptors which when activated result in increases in [Ca(2+)](i).

Aequorin↗
PubMed1987

Sensitivity of protein and RNA synthesis to emetine in axenic Entamoeba histolytica.

The action of emetine on the incorporation of (14C)1-DL-valine and (14C)-8-adenine in TCA insoluble fraction of axenic Entamoeba histolytica was investigated. These compounds were almost exclusively incorporated in the 'protein' and 'RNA' fractions, respectively. Incorporation of the purine showed a significantly higher sensitivity to emetine. While the percentage inhibition of valine incorporation by emetine decreased with increasing pH, the susceptibility of adenine incorporation was greater in the alkaline range.

Adenine↗
PubMed1987

Monitoring of phenobarbitone in epileptic children.

Seventy-five children with different nutritional status, who were receiving phenobarbitone for treatment of various seizure disorders, were monitored for their plasma steady state level, therapeutic efficacy and toxicity. A wide inter individual variation in the steady state level was observed. About 10 percent of them had subtherapeutic level, while nearly 30 percent of them had potentially toxic levels, the remaining were within therapeutic range of 10-25 micrograms/ml. Poor compliance was found to be an important contributing factor for the variations in the level. Steady state levels were significantly higher in children with grade II protein energy malnutrition (PEM) than normally nourished children. A good correlation existed between plasma drug level and therapeutic response in nearly 60 percent of the children. Clinical toxicity was observed in nearly two thirds of the children, sedation and behavioral problems being the most common. The importance of monitoring the drug level is discussed for the proper management of epileptic children.

Child↗
PubMed1987

Monitoring of drug therapy in epileptic children.

Twenty children who were receiving phenytoin either alone or in combination with phenobarbitone, were monitored for their plasma steady state levels. A wide interindividual variation was observed in steady state plasma levels. Among children who were receiving only phenytoin, nearly 50% had drug levels above 10 micrograms/ml. It was observed that children with drug levels above 10 micrograms/ml exhibited good therapeutic response. Two children who were presented with acute toxicity showed drug levels above 40 micrograms/ml. Children receiving combination of phenytoin and phenobarbitone showed extreme degree of variation in drug levels which was reflective of drug interaction. In view of the wide interindividual variation in level of phenytoin and the unpredictability of interaction with other anticonvulsants, the monitoring of drug levels become mandatory.

Child↗