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Biomedical subjects

S S Nathan

Publications and source records attributed to S S Nathan.

5 recordsLinked to original sources

The operative treatment of closed tibial fractures.

The tibia is a subcutaneous bone. Operative fixation of tibial fractures is a demanding undertaking. Thirty-five patients with 36 tibial fractures were admitted to our institution between May 1995 and April 1996. The patients were predominantly male (male to female ratio of 4) and the average age of the patients was 31.4 years (range 14 to 67 years). Ten fractures were located in the proximal third, 18 in the middle third and 8 in the distal third. The indications for operation included displaced intra-articular fragments, failed conservative treatment, compartment syndrome, multiple fractures and unstable fracture configuration. Operative procedures included plating in 29 cases and nailing in 7 cases. These patients were reviewed retrospectively and assessed for complications and radiological and functional outcome. The overall results were satisfactory in 88.9% and poor in 11.1%. The complications were reviewed and various factors affecting the incidences analysed. Three deep infections occurred. All were found after discharge from inpatient care. A prolonged interval between admission and surgery as well as high energy of impact are thought to be the main contributing factors.

Adolescent↗

Influence of host plant on growth and reproduction of Aphis nerii and feeding and prey utilization of its predator Menochilus sexmaculatus.

Influence of different physiological stages (young, mature and senescent) of Calotropis gigantea leaves on growth and reproductive ability of A. nerii and feeding, prey utilization, fecundity and lipid content of its predator M. sexmaculatus were investigated. Increased reproductive period, total life span and reproduction of nymphs per female of A. nerii were observed when reared on mature leaves. This relative preference of A. nerii and maximum utilization of mature leaves as compared to other physiological aged leaves are mainly due to changes in the chemical composition such as protein, carbohydrate, lipid, amino acid, nitrogen and phenolic of C. gigantea. Further, aphids reared on mature leaves influenced its predator's (M. sexmaculatus) growth, prey utilization and reproductive performances. Fecundity and longevity were high, while developmental time of predator was shorter on mature leaves fed aphid. Maximum prey utilization and increased efficiency of ingested and digested food of predator was observed on mature leaves reared aphid. The results are interpreted and discussed in relation to plant aphid and predator interaction (tritrophic).

Animals↗

Determination of current density distributions generated by electrical stimulation of the human cerebral cortex.

With the use of a 3-dimensional finite element model of the human brain based on structural data from MRI scans, we simulated patterns of current flow in the cerebral hemisphere with different types of electrical stimulation. Five different tissue types were incorporated into the model based on conductivities taken from the literature. The boundary value problem derived from Laplace's equation was solved with a quasi-static approximation. Transcranial electrical stimulation with scalp electrodes was poorly focussed and required high levels of current for stimulation of the cortex. Direct cortical stimulation with bipolar (adjacent) electrodes was found to be very effective in producing localized current flows. Unipolar cortical stimulation (with a more distant reference electrode) produced higher current densities at the same stimulating current as did bipolar stimulation, but stimulated a larger region of the cortex. With the simulated electrodes resting on the pia-arachnoid, as usually occurs clinically, there was significant shunting of the current (7/8 of the total current) through the CSF. Possible changes in electrodes and stimulation parameters that might improve stimulation procedures are considered.

Cerebral Cortex↗

Cutaneous aspergillosis.

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Antineoplastic Combined Chemotherapy Protocols↗