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Biomedical subjects

S Gunasekaran

Publications and source records attributed to S Gunasekaran.

68 records · Page 4Linked to original sources
PubMed1987

Effect of topical beta APN application on evoked potential conduction in rat sciatic nerve and spinal cord.

The purpose of this study is to evaluate possible toxic effects of beta-aminopropionitrile fumarate (beta APN), a lathyrogenic agent that inhibits fibrosis. This drug has been considered for use as an adjunct to surgical repair after topical application upon peripheral and central nervous system structures. In vivo and in vitro studies were done using rats to study the dose dependent neurotoxicity of this water soluble chemical. The results indicate that when the neural sheaths are removed the amplitude of the evoked sciatic nerve potential is irreversibly suppressed from 1 to 10 mM concentrations of beta APN. Nerve conduction velocities are relatively less affected with reduction from 43 to 35 m/sec by beta APN immersion. Similarly, the spinal cord studies show that when the dura and arachnoid are opened and damaged, 0.1 mM beta APN causes increased latency (from 9.9 to 14.5 msec) and decreased amplitude (from 79.4 to 56.8 microV) of cortical somatosensory evoked potentials. Possible mechanisms for the neurotoxic effects of beta APN are discussed.

Aminopropionitrile↗
PubMed1986

Vitamin D3 and avian bone in vitro: stimulation of calcium movement into Japanese quail calvaria.

Addition of 1,25 dihydroxyvitamin D3 (1,25(OH)2D3) to cultured neonatal mouse calvaria has consistently led to bone resorption as determined by an increase in medium calcium. No such effect on avian bone has been widely reported. We have tested the in vitro effects of 1,25(OH)2D3 on 48- and 96-hour cultures of calvaria removed from both sexes of Japanese quail at various ages. No effect of 1,25(OH)2D3 on net calcium movement was seen in cultures of calvaria removed from neonatal (5-day), 1-week, and 2-week-old quail. In cultures of calvaria from 6-week-old female quail, addition of 1,25(OH)2D3 resulted in a fall in medium total and ionic calcium concentrations after 48 and 96 hours of incubation, indicating an uptake of calcium by the bones. A maximal effect was seen at 1 X 10(-7) M 1,25(OH)2D3. Bones removed from male and female quail showed no difference in response between the sexes. Bones removed from 5-, 4-, and 3-week-old male and female quail exhibited a progressively decreasing response with decreasing age. After 6 weeks of age female birds begin to exhibit hypercalcemia associated with reproductive activity. Bones removed from 7- and 8-week-old female quail responded to 1,25(OH)2D3 in a similar fashion whether they were hypercalcemic (7 weeks, 20.3 mg/dl; 8 weeks, 31.7 mg/dl), or normocalcemic (10.1 mg/dl). This stimulatory effect of 1,25(OH)2D3 on calcium uptake by avian bone is in sharp contrast to the hormone's effect in cultures of perinatal mammalian bones, which consistently respond to 1,25(OH)2D3 by releasing calcium into the medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1986

Vitamin D3 and avian bone in vitro: specificity of effect on Japanese quail calvaria.

Calcitriol (1,25(OH)2D3) has been shown, under certain conditions, to elicit an in vitro response in adult avian calvarium which may be interpreted as calcium uptake by the bone. The present investigation was undertaken to study the specificity of this response. Calvaria were removed from 6-week-old female Japanese quail and cultured for periods of up to 96 hours at 37 degrees C in 5% CO2/95% air. 1,25(OH)2D3 induced a fall in the medium total and ionic calcium concentrations at both 48 hours and 96 hours of incubation; these responses were not blocked by the presence of 10(-4) M acetazolamide. Bovine parathyroid hormone (bPTH(1-34] at 10(-7) M, and dibutyryl cyclic AMP (DBcAMP) at 10(-4) M, had no effect on the medium calcium. In contrast, forskolin at 10(-4) M induced a marked fall in medium calcium concentrations, particularly at 48 hours. The specificity was also studied with respect to vitamin D3 and its two major metabolites. 1,25(OH)2D3 exhibited a bell-shaped dose-response relationship with the maximal effect at 10(-7) M. In contrast, the other two compounds elicited no effects at 10(-7) M or 10(-6) M; significant responses were observed at 10(-5) M with both agents. In general, 25-dihydroxyvitamin D3 (25OHD3) was more potent than vitamin D3. These findings suggest that the medium calcium response to 1,25(OH)2D3, interpreted as calcium uptake by the cultured adult avian bone, is relatively specific among calcemic agents; the response was elicited by forskolin but not by bPTH(1-34) or DBcAMP.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetazolamide↗
PubMed1986

Optimal energy management in grain drying.

Grain drying is very specific to the geographic location, kind of drying system, and the type of grain. Under a given set of conditions, the optimal system can be selected based on careful evaluation. However, a good choice of drying systems, procedures, and management practices can be made from the information already available. The review of several grain-drying procedures has provided some insight in making a quick evaluation of the process and arriving at the most suitable system for a particular application. Despite extensive research efforts, the present knowledge of grain drying is yet insufficient to optimally design each drying process with respect to capacity, quality, and energy requirement. There is a need for incorporating grain and air parameters more accurately. It is also important to develop comprehensive drying simulation models to encompass agronomic practices, such as planting and harvesting. Recent efforts indicate a strong influence of planting and harvesting strategies on optimal drying and storage system selection. Results of the varietal trials at Ohio State University indicate that it is now possible to select midseason varieties, which dry down rapidly, without sacrificing yield. Also, low moisture at harvest is important to the energy management process because it affects total drying time and energy required. It is also important from a quality standpoint because kernel damage increases rapidly at harvesting moisture levels above 25%. The trend in grain-dryer design has shifted from focusing on drying capacity and operation reliability to energy consumption. The development in design of energy efficient continuous-flow dryers has been significant. Multistage concurrentflow dryers are excellent examples. Various aspects of dryer staging for efficient operation and control are yet to be determined. Recirculation of the exhaust air is a proven method of improving energy efficiency. Likewise, in batch-in-bin systems, stirring and intermittent drying are worth considering. Further research is required to formulate the best procedures for exhaust air recirculation and intermittent drying. Low temperature drying has a great potential in the U.S. corn belt. The suitability of low temperature drying at other places and for grains other than corn has not yet been well established. Energy savings resulting from low temperature drying entail careful planning and management on the part of the operator. Poor design and operation can result in a serious deterioration in grain quality.(ABSTRACT TRUNCATED AT 400 WORDS)

Conservation of Energy Resources↗
PubMed1986

Forskolin-induced bone resorption in neonatal mouse calvaria in vitro.

The role of cyclic adenosine 3',5'-monophosphate (cAMP) in inducing bone resorption was studied in neonatal mouse calvaria in vitro. Forskolin, a stimulator of adenylate cyclase, increased the medium calcium concentration at 96 hr of incubation, indicating enhanced bone resorption. Bone resorption was observed between 1 X 10(-4) and 1 X 10(-6) M forskolin; the maximal effect was at 1 X 10(-5) M and there was no effect at 1 X 10(-7) M. Lactic acid release was increased during the 96 hr of incubation in proportion to the calcium release in the media. The bone acid phosphatase activity was increased and the alkaline phosphatase activity was decreased. Bone carbonic anhydrase activity was increased more than twofold. Forskolin-induced bone resorption was significantly but incompletely inhibited by 10(-4) M acetazolamide, a carbonic acid anhydrase inhibitor. These findings support the concept that carbonic anhydrase plays a significant role in bone resorption.

Acetazolamide↗
PubMed1985

Therapeutic effects of disulfiram in spinal cord contusion of rabbits.

The purpose of the present investigation was to evaluate methods to prevent the development of the immediate and delayed tissue damage in the injured spinal cord by early drug (disulfiram) interference with the molecular mechanism of tissue injury. The edematous inflammation as well as change in the levels and distribution of metallic ions like calcium following spinal cord contusion is known to contribute to the destructive process. A contusion model was applied in the spinal cord of rabbits using a pneumatic impactor. The effect of the systemically administered drug, disulfiram, in the traumatized spinal cord was determined by assaying the tissue water and Ca2+ contents at different locations of the spinal cord. A significant increase in the levels of the assayed parameters at the injured site of the spinal cord is markedly reduced by the pretreatment with disulfiram.

Animals↗
PubMed1984

Nondestructive optical methods of food quality evaluation.

Quality control is an important aspect of food production and processing from the point of view of providing foods of acceptable nutritional value, and for providing safety of products. Several characteristics such as size, shape, density, maturity, moisture content, oil content, flavor, firmness, tenderness, color, defects, blemishes, etc., are routinely used in the quality control of agricultural and biological food products. Until recently, most analytical techniques used in quality control required isolation of the food component of interest. The original properties of the product are, therefore, destroyed during sample preparation and analysis. Oftentimes, such analyses are expensive, time consuming, and require sophisticated instrumentation, and hence are not suited for "on-line" quality control of food products. Recent progress in the development of instrumentation utilizing the optical properties of food products has provided several nondestructive techniques for quality evaluation. Most optical methods of nondestructive nature make use of the characteristic absorption spectra of components of interest. Such methods are highly sensitive, rapid, and reproducible, and have been successively used in routine "on-line" quality control of a large number of samples. In this article, theoretical considerations in the development of nondestructive analytical techniques based on the optical properties of several agricultural and biological products are briefly reviewed. A major emphasis is placed on quality control methods that are particularly useful in maturity and/or ripeness evaluation of food products, the detection of external and internal defects, and the subsequent development of automatic sorting machines for on-line measurement of quality.

Food↗
PubMed1983

Distribution of disulfiram in brain after carotid ligation in gerbils.

Aiming whether intraperitoneal administration of disulfiram (tetraethyl thiuram disulfide, DS) achieves potentially therapeutic drug concentrations in brain tissue, the behaviour of blood-brain barrier (BBB) to 14C-labelled DS in cerebral ischemia with and without simultaneous administration of dimethylsulfoxide (DMSO) was studied in Mongolian gerbils subjected to left common carotid artery (CCA) occlusion. The results indicated that: (a) the permeability of DS through the BBB was significantly enhanced in the ischemic brain during the initial 30 min duration after DS administration; (b) administration of DMSO increased the entry of DS into the ischemic brain five-fold during the first 30 min and it was significantly higher even at the 60 min sampling period; (3) in general, the content of DS in the brain was quickly reduced with time.

Animals↗
PubMed1982

Effect of amino-acids on secretion of insulin by isolated islets of the monkey.

Insulin secretion was monitored in monkey islets isolated by collagenase digestion and exposed to leucine and arginine with and without glucose. Leucine by itself (10 to 40 mmol/l) elicited concentration-dependent insulin secretion. At 40 mmol/l, leucine was approximately 60% as effective as glucose (16.7 mmol/l). The response to leucine was increased at low glucose concentrations. In high concentrations (20 and 40 mmol/l), arginine by itself was a poor stimulant. The effect of arginine was enhanced at low glucose concentrations (2.8 to 5.6 mmol/l). At high glucose concentrations neither amino-acid produced any significant further increase in insulin release.

Animals↗
PubMed1979

Studies on insulin secreted by isolated islets of the monkey, Macaca radiata radiata.

The effects of various experimental conditions during the isolation of monkey islets by the collagenase method on the insulinogenic response of the isolated islets to glucose have been studied and compared with rat islets isolated under similar conditions. The monkey islets gave a normal response for at least 120 min. The results are compared with available studies on primate islets.

Animals↗