Search PubMed⌕ Search

Biomedical subjects

V Gupta

Publications and source records attributed to V Gupta.

At least 307 records · Page 17Linked to original sources
PubMed1977

Serum aspirin esterase activity in women with habitual aspirin intake.

A method for the determination of aspirin esterase activity in serum is described. Sera from 59 pregnant women who were habitual aspirin users were found to have a mean enzyme activity value statistically lower than those of 68 non-pregnant women controls or of 12 pregnant women controls who were either occasional users of the drug or were non-users. The distribution of enzyme activity in the experimental group was also significantly different from that of the control group. It is postulated that the low enzyme activity may further aggravate the injurious effects of high intake of aspirin.

Adult↗
PubMed1976

Exchangeable intracellular methotrexate levels in the presence and absence of vincristine at extracellular drug concentrations relevant to those achieved in high-dose methotrexate-folinic acid "rescue" protocols.

Studies were undertaken to (a) assess intracellular methotrexate (MTX) levels at extracellular drug concentrations comparable to those achieved in high-dose MTX-folinic acid rescue protocols and (b) establish whether there is a rationale for the use of vincristine in these regimens. The data indicate that only low levels of exchangeable MTX (intracellular MTX in excess of the tightly bound fraction) accumulated in Ehrlich ascites tumor cells at high extracellular MTX concentration. For instance, the exchangeable steady-state intracellular MTX level was approximately 6.5 muM when the extracellular drug concentration was 85 muM. Over the interval of these experiments, exchangeable intracellular MTX did not exceed approximately 10 muM even when extracellular MTX was raised to 250 muM. These exchangeable intracellular MTX concentrations are comparable to those levels required experimentally to suppress (a) tetrahydrofolate synthesis from dihydrofolate and (b) tetrahydrofolate-dependent purine, pyrimidine, and amino acid synthesis in these cells in vitro. Vincristine (10 muM) augmented net MTX accumulation when the extracellular MTX level was 10, 100, or 250 muM. The limited capacity of cells to accumulate exchangeable intracellular MTX and the apparent role for this intracellular MTX component in achieving the metabolic effects of this agent may account for the necessity for high MTX blood levels in the treatment of some tumors and may be the basis, in part, for the enhanced chemotherapeutic efficacy of high-dose MTX regimens. These studies provide a rationale for the combined use of vincristine and MTX in high-dose MTX protocols. The addition of vincristine may permit the achievement of the level of exchangeable intracellular MTX that is required to critically inhibit tetrahydrofolate synthesis without an increase in the extracellular MTX concentration. This may permit a reduced MTX dose, diminishing the excretory load on the kidney and minimizing nephrotoxicity due to deposition of MTX in the renal tubule and interstitium. While the data indicate that the ratio of the concentration of exchangeable intracellular MTX to the extracellular drug concentration may be very low under steady-state conditions at high extracellular drug levels, further studies are required to establish that these steady-state gradients for MTX represent nonequilibrium conditions.

Animals↗
PubMed1970

Three-dimensional organization of the 30S ribosomal proteins from Escherichia coli. I. Preliminary classification of the proteins.

30S ribosomal subunits from Escherichia coli were reacted with three protein reagents. After reaction, the ribosomal proteins were extracted and examined; of the 20 proteins known to compose the particle, nine did not react with any of the three reagents. We have tentatively classified these proteins as "internal," and the remaining eleven as "external." A strong correlation was found between these results and the sequence of assembly. Those proteins which enter the assembly process early are classed as internal, whereas those proteins found to participate later in the assembly sequence are classed as external.

Bacterial Proteins↗
PubMedDate not supplied

Noninvasive acceleration measurements to characterize knee arthritis and chondromalacia.

Devising techniques and instrumentation for early detection of knee arthritis and chondromalacia presents a challenge in the domain of biomedical engineering. The purpose of the present investigation was to characterize normal knees and knees affected by osteoarthritis, rheumatoid arthritis, and chondromalacia using a set of noninvasive acceleration measurements. Ultraminiature accelerometers were placed on the skin over the patella in four groups of subjects, and acceleration measurements were obtained during leg rotation. Acceleration measurements were significantly different in the four groups of subjects in the time and frequency domains. Power spectral analysis revealed that the average power was significantly different for these groups over a 100-500 Hz range. Noninvasive acceleration measurements can characterize the normal, arthritis, and chondromalacia knees. However, a study on a larger group of subjects is indicated.

Acceleration↗
PubMedDate not supplied

Management of posterior capsule tears.

Any breach in the continuity of the posterior capsule is defined as a posterior capsule tear. Posterior capsule tears can be preexisting (congenital or traumatic), spontaneous, or intrasurgical. Preexisting/congenital posterior capsule tears have been related to an intrauterine insult. Posterior capsule tears due to trauma may occur as a consequence of direct mechanical impact due to perforation or blunt injury. Depending on the duration of time between the posterior capsular trauma and the cataract surgery, these posterior capsule tears can have different features. Intrasurgical posterior capsule tears are the most common and can occur during any stage of cataract surgery. Also, they may be planned in the form of primary posterior capsulorhexis. The conventional management consists of prevention of mixture of cortical matter with vitreous, dry aspiration, and anterior vitrectomy, if required. In addition, during phacoemulsification low flow rate, high vacuum, and low ultrasound are advocated if a posterior capsule tear occurs. Dislocated nucleus or nuclear fragments require vitrectomy and the use of perfluorocarbon liquids. In the presence of a posterior capsule tear, the IOL can be placed in the sulcus, if the capsular rim is available, or in the bag, if the tear is small. Scleral fixated posterior chamber lenses and anterior chamber IOLs can be implanted when the posterior capsule tear is large.

Eye Injuries↗