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Biomedical subjects

S G Patil

Publications and source records attributed to S G Patil.

7 recordsLinked to original sources
PubMed2004

Dynamic depth-dependent osmotic swelling and solute diffusion in articular cartilage monitored using real-time ultrasound.

The objective of this study was to investigate the feasibility of ultrasonic monitoring for the transient depth-dependent osmotic swelling and solute diffusion in normal and degenerated articular cartilage (artC) tissues. Full-thickness artC specimens were collected from fresh bovine patellae. The artC specimens were continuously monitored using a focused beam of 50 MHz ultrasound (US) during sequential changes of the bathing solution from 0.15 mol/L to 2 mol/L saline, 0.15 mol/L saline, 1 mg/mL trypsin solution, 0.15 mol/L saline, 2 mol/L saline and back to 0.15 mol/L saline. The transient displacements of US echoes from the artC tissues at different depths were used to represent the tissue deformation and the NaCl diffusion. The trypsin solution was used selectively to digest the proteoglycans in artC. It was demonstrated that high-frequency US was feasible for monitoring the transient osmotic swelling, solute transport and progressive degeneration of artC in real-time. Preliminary results showed that the normal bovine patellar artC shrank during the first several minutes and then recovered to its original state in approximately 1 h when the solution was changed from 0.15 mol/L to 2 mol/L saline. Degenerated artC showed neither shrinkage nor recovery during the same process. In addition, a dehydrated-hydrated artC specimen showed much stronger shrinkage and it resumed the original state when the solution was changed from 2 mol/L back to 0.15 mol/L saline. The diffusion of NaCl and the digestion process of proteoglycans induced by trypsin were also successfully monitored in real-time.

Animals↗
PubMed2004

Measurement of depth-dependence and anisotropy of ultrasound speed of bovine articular cartilage in vitro.

The inhomogeneous and anisotropic mechanical properties and structural components of articular cartilage (artC) may cause complex acoustic properties in this important tissue. In this study, we used 50-MHz ultrasound (US) to measure in vitro the depth-dependence and anisotropy of the US speed of artC collected from the bovine patellae. The US speeds of 18 disk artC specimens sampled from 18 different patellae were measured in two orthogonal directions. One full-thickness layer (n=18) and three horizontal slices (n=18 x 3) with approximately equal thickness were prepared from each artC disk and measured with the US beam perpendicular to the artC surface. One full-thickness vertical slice (n=10) was measured at different depths with the US beam parallel to the artC surface. The measured US speeds of artC in the two orthogonal directions were significantly different (p < 0.001). The US speeds also significantly increased with the increase of tissue depth for both measurement directions (p < 0.001). The US speeds of artC from the superficial to deep regions were 1518 +/- 17 (mean + SD), 1532 +/- 26 and 1554 +/- 42 m/s for the US beam parallel to the artC surface, and 1574 +/- 29, 1621 +/- 34 and 1701 +/- 36 m/s for the beam perpendicular to the artC surface. The sound speed of the full-thickness layer was 1636 +/- 25 m/s. The results suggested that the depth-dependence and anisotropy of the US speed in artC should be taken into account when US is used for the artC measurement. It was also demonstrated in this study, using additional specimens (5 x 2), that the swelling of artC after detaching from its subchondral bone could cause the change of its sound speed.

Animals↗
PubMed2004

Myasthenia gravis.

Myasthenia gravis is the prototype neuromuscular disease with immunological pathogenesis. The recognition and interpretation of the symptoms should be stressed as the diagnosis is initially achieved on clinical ground. Tests in the areas of immunology, electrophysiology and imaging further help the diagnosis, management and prognosis of the condition. The recent knowledge of immunology seems to point to variations in the immune abnormalities, but it remains to be seen whether the differences have clinical relevance. With the availability of intensive care units, the management of acute events in the myasthenic patients has improved considerably and the morbidity is reduced. Long term remissions are achievable in majority of patients, with supervised use of immunosuppression. In the modern times, the grave connotations of the name myasthenia gravis may be only rarely justified.

Antibodies↗
PubMed1996

Chemoenzymatic synthesis of D(-)phenylglycine using hydantoinase of Pseudomonas desmolyticum resting cells.

We screened 125 Pseudomonas strains from our culture collection for the production of hydantoinase activity using DL-phenylhydantoin as a substrate. Pseudomonas desmolyticum NCIM 2112 was found to be the best hydantoinase (dihydropyrimidinase E.C. 3.5.2.2) producer. The enzymatic reactions were carried out using 18-20-h grown cells in nutrient broth and 5-phenylhydantoin as the substrate. Optimization studies for the biotransformation reaction were performed to increase product yield. The optimum pH and temperature for D(-)N-carbamoylphenylglycine production were 9.5 and 30 degrees C, respectively. Biotransformation under these alkaline conditions allowed the complete conversion of 27.0 g l-1 of DL-phenylhydantoin to 26.5 g l-1 of N-carbamoylphenylglycine within 24 h, with a molar yield of 90%. The hydantoinase involved in this biotransformation process was strictly D-stereospecific, because the product isolated was pure D(-)N-carbamoylphenylglycine. This pure product was further chemically converted to D(-)phenylglycine using nitrous acid with an 80% chemical yield. Thus, the overall conversion efficiency of DL-5-phenylhydantoin to D(-)phenylglycine was found to be 65-68%.

Amidohydrolases↗
PubMed1992

Protection of Aspergillus niger cellulases by urea during growth on glucose or glycerol supplemented media.

The cellulase enzymes of Aspergillus niger were found to undergo catabolite repression in the presence of glucose and glycerol accompanied by sudden drop in pH of the fermentation medium below 2.0. This sudden drop in pH caused inactivation of cellulolytic enzymes produced by Aspergillus niger. The supplementation of nitrogen sources, especially urea, protects A. niger cellulases from inactivation caused by a sudden drop in pH, since urea helped to maintain the pH of the fermentation medium between 3.5 and 4.5. The role of urea in the protection of cellulase was more prominent when it was used in combination with glycerol (5%).

Aspergillus niger↗
PubMed1991

Optimization of cellulase production by Aspergillus niger NCIM 1207.

Aspergillus niger NCIM 1207 produces high levels of extracellular beta-glucosidase and xylanase activities in submerged fermentation. Among the nitrogen sources, ammonium sulfate, ammonium dihydrogen orthophosphate, and corn-steep liquor were the best for the production of cellulolytic enzymes by A. niger. The optimum pH and temperature for cellulase production were 3.0-5.5 and 28 degrees C, respectively. The cellulase complex of this strain was found to undergo catabolite repression in the presence of high concentrations of glucose. Glycerol at all concentrations caused catabolite repression of cellulase production. The addition of glucose (up to 1% concentration) enhanced the production of cellulolytic enzymes, but a higher concentration of glucose effected the pronounced repression of enzymes. Generally the growth on glucose- or glycerol-containing medium was accompanied by a sudden drop in the pH of the fermentation medium to 2.0.

Aspergillus niger↗