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Biomedical subjects

S Gunasekaran

Publications and source records attributed to S Gunasekaran.

At least 19 recordsLinked to original sources

ENT in general practice: training, experience and referral rates.

A postal survey of 500 general practitioners (GPs) in south-west England was undertaken to evaluate the levels of undergraduate and postgraduate otolaryngology training and/or experience received by GPs in that area. Most GPs had received two weeks of undergraduate training in ENT, which had involved no formal assessment. Three-quarters of GPs considered this inadequate. A quarter of GPs had completed a hospital post in ENT prior to entering general practice, most of which lasted three months. Sixty-one per cent of GPs had received some formal postgraduate training in ENT, in the form of courses, lectures or hospital training sessions. Almost half of the GPs considered this inadequate. Seventy-five per cent of GPs stated they would like further training in ENT. Subjective estimates of referral rates to hospital ENT specialist clinics varied considerably. This study illustrates the variability and level of dissatisfaction regarding ENT training amongst GPs at both undergraduate and postgraduate levels.

Education, Medical, Undergraduate↗

Vibrational spectra and normal coordinate analysis of diazepam, phenytoin and phenobarbitone.

Vibrational spectroscopy is an important tool for the structural investigation of the organic molecules. In the present investigation, a normal coordinate analysis has been carried out on some anti-epileptic drugs, viz. diazepam, phenytoin and phenobarbitone. Diazepam is a derivative of benzodiazepine, phenytoin is a derivative of hydanation and pheonobarbitone is a barbiturate. The infrared spectra of the compounds are recorded in the region 4000-400 cm(-1) and Raman spectra are recorded in the region 3500-50 cm(-1). From the structural point of view, diazepam, phenytoin and phenobarbitone have been assumed to C(s) point group. A systematic set of symmetry coordinates has been constructed for these compounds and Wilson's FG matrix method has been applied for the normal coordinate analysis using general quadratic valance force field. The potential energy distribution is also calculated to check the vibrational band assignments.

Amino Acids, Aromatic↗

Stenting for bilateral congenital choanal atresia--a new technique.

We describe a new nasal stent for the treatment of bilateral congenital choanal atresia. The stent is made up of reinforced endotracheal tube mounted on a portex carrier tube. It potentially causes less internal crusting and stent blockage and is secured without sutures. It remains patent for at least 4 weeks. We have used the stent successfully in six patients between 1998 and 2004 at Leeds General Infirmary and present the data collected retrospectively. The current practice in the UK for treatment and stenting for congenital choanal atresia was investigated by a prospective internet based questionnaire sent to 18 consultant paediatric otolaryngologists of whom 12 (67%) responded. Their experience and results are reported. The literature has been reviewed.

Choanal Atresia↗

Vibrational spectral investigation on xanthine and its derivatives--theophylline, caffeine and theobromine.

A normal coordinate analysis has been carried out on four compounds having a similar ring structure with different side chain substitutions, which are xanthine, caffeine, theophylline, and theobromine. Xanthine is chemically known as 2,6-dihydroxy purine. Caffeine, theophylline and theobromine are methylated xanthines. Considering the methyl groups as point mass, the number of normal modes of vibrations can be distributed as Gamma(vib) = 27 A' + 12 A" based on C(s) point group symmetry associated with the structures. In the present work 15 A' and 12 A'' normal modes are considered. A new set of orthonormal symmetry co-ordinates have been constructed. Wilson's F-G matrix method has been adopted for the normal coordinate analysis. A satisfactory vibrational band assignment has been made by employing the FTIR and FT Raman spectra of the compounds. The potential energy distribution is calculated with the arrived values of the force constants and hence the agreement of the frequency assignment has been checked.

Caffeine↗

Reversal of diabetes by xenotransplantation of monkey pancreatic islets in rats: an ultrastructural study.

OBJECTIVES: Transplantation of pancreatic islets is considered a potential curative treatment of type 1 diabetes. Electron microscopy plays a major role in the evaluation of pancreatic islets. The aim of this study was to study the reversal of diabetes by xenotransplantation of monkey pancreatic islets into diabetic recipient by functional and structural findings. METHODS: Islets of Langerhans were isolated from monkeys by collagenase digestion method. Two days after the induction of diabetes in rats with streptozotocin, diabetes was confirmed. Freshly isolated islets were transplanted under the renal capsule of the diabetic rats. The recipients received cyclosporin A (30 mg/kg) every day. Fasting plasma glucose was estimated on days 3, 7, and 14 after transplantation. The presence of glucose and ketone in urine was checked. After 14 days, the grafts were removed and processed for light and electron microscopic study. RESULTS: After the induction of diabetes, the mean fasting plasma glucose was 347.20 mg/dL. On day 3 after transplantation, the mean fasting plasma glucose value was 100 mg/dL. The mean fasting plasma glucose was 94.6 mg/dL on day 7 and 94.8 mg/dL on day 14. Histology of the monkey islet grafts after 14 days showed the survival of pancreatic islets. Ultrastructure of the same grafts showed the presence of alpha, beta, and delta granules similar to those of native pancreatic islets with the other cellular organelles. CONCLUSION: The diabetic state of rats can be reversed by xenotransplantation of isolated monkey islets. Ultrastructural study confirms the normal synthesis and release of islet hormones. The released insulin from transplanted monkey islets had lowered the plasma glucose level of recipient rats.

Animals↗

Normal hematological indices, blood chemistry and histology and ultrastructure of pancreatic islets in the wild Indian bonnet monkeys (Macaca radiata radiata).

The present study is aimed at determining some haematological and biochemical parameters in the wild Indian bonnet monkeys as also the microscopic and ultrastructural characteristics of their pancreatic islets. Adult wild Indian bonnet monkeys (Macaca radiata radiata) of both sexes weighing between 2.5 and 4 kg were used in these experiments. Their platelet, reticulocyte and total leukocyte counts and the blood concentrations of hemoglobin and plasma proteins and the serum concentrations of aspartate amino transferase, alanine amino transferase and calcium are similar to the values reported for M. mulatta. Plasma glucose is lower when compared with reported values of M. mulatta and M. fascicularis. Insulin levels are comparable with those of M. mulatta and M. nigra. Histology of islets is similar to that of humans. Ovoid cell collections of islet cells are scattered throughout the pancreas. Ultrastructure of A, B and D cells is similar to humans. These findings suggest that this relatively underutilized macaques may be a suitable model for biomedical research.

Alanine Transaminase↗

Bilateral internal jugular vein thrombosis in a child with protein S deficiency.

Internal jugular vein thrombosis is a rare but treatable disorder with most of the reports in the literature related to the adult population. The most common reported cause is iatrogenic trauma to the internal jugular vein and only a few cases have been reported in the paediatric population. We present a case of bilateral internal jugular venous thrombosis with pulmonary and cerebral complications in a 14-year-old girl with protein S deficiency. This problem has not been previously reported in the world literature.

Adolescent↗

Short communication: comparison of covered and uncovered Schreiber test for cheese meltability evaluation.

Schreiber meltability tests were performed on glass Petri dishes, with and without the Petri dish cover placed over the cheese samples, at 100, 150, and 232 degrees C. Meltability of different process cheese and Cheddar cheese samples was determined based on the melt spread distance and area. At the test temperature of 232 degrees C, the covered Schreiber was significantly superior to the uncovered test because of no crust formation, no browning, and a circular melting pattern, which were attributed to the barrier effect of covering the cheese samples (which inhibits moisture loss during the test). The covered Schreiber test data were statistically more robust as measured by the lower average coefficient of variation than the data from the traditional uncovered Schreiber test.

Cheese↗

Effect of streptozotocin on the ultrastructure of rat pancreatic islets.

Our objective was to study the effects of three (30, 40, and 50 mg/kg) doses of Streptozotocin (STZ) on fasting plasma glucose level (FPG) and observe its effects at the cellular level in rat pancreas by electron microscopy. FPG was measured in rats before induction of diabetes and then on 3, 7, and 14 days after induction of diabetes with STZ. Keto diastix urine strips were used to check urine glucose and ketone bodies. Two weeks after the induction of diabetes, the rat pancreas was removed and fixed for light and electron microscopic studies. Three days after induction, the mean FPG level was 112 mg/dl in Group I (30 mg/kg STZ), 217 mg/dl in Group II (40 mg/kg STZ), and 376 mg/dl in Group III (50 mg/kg STZ). Histology was normal in Group I but revealed altered islet structure in Groups II and III. Ultrastructure revealed intact D cells in all three groups. The focal mitochondria and Golgi complex swelling found in A and B cells was occasional in Group I and frequent in Groups II and III. Swelling of other organelles and reduction in the size and number of granules was further observed in Group III. It is our conclusion that the 30-mg/kg body weight STZ produces mild changes while 50 mg/kg proves to be fatal. STZ at 40 mg/kg has a moderate effect on plasma glucose as well as on the islets of Langerhans at a cellular level.

Animals↗

Insulin secretory characteristics of monkey pancreatic islets: a simple method of islet isolation and the effect of various density gradients on separation.

We describe a simple stationary digestion method of islet isolation and separation by various density gradients from monkey pancreas (Macaca radiata radiata). Effective method, different types and concentrations of collagenase were standardized. Sigma type XI collagenase yielded >1000 islets/gram pancreas at the concentration of 4 mg/ml and 3 ml Hank's/gram pancreas. Slow digestion with less concentration of collagenase was suitable for monkey islet isolation. Discontinuous density gradients of bovine serum albumin (BSA) and dextran were compared with standard Ficoll for separation of islets. Islet yield (1038 +/- 81), insulin secretory response (stimulation index, S.I.11) and histological examination revealed dextran gradients were more appropriate for monkey islets when compared to BSA and Ficoll. Insulin secretory characteristics of monkey islets were studied by exposing them to low and high concentrations glucose (S.I.11.5), arginine (S.I.4.2), leucine (S.I.2.3) and tolbutamide (S.I.1.7). The results indicated that the magnitude of glucose induced insulin secretion of monkey islet is about half as that of rat and mouse islets. However, it is higher than that of porcine and bovine islets. In conclusion, the knowledge of insulin secretory ability of Indian bonnet monkey islets together with the techniques of isolation and separation are useful tool for diabetic research especially islet transplantation.

Amino Acids↗

Fractal characterization of bpn weights evolution.

Training methodology of the Back Propagation Network (BPN) is well documented. One aspect of BPN that requires investigation is whether or not the BPN would get trained for a given training data set and architecture. In this paper the behavior of the BPN is analyzed during its training phase considering convergent and divergent training data sets. Evolution of the weights during the training phase was monitored for the purpose of analysis. The evolution of weights was plotted as return map and was characterized by means of fractal dimension. This fractal dimensional analysis of the weight evolution trajectories is used to provide a new insight to understand the behavior of BPN and dynamics in the evolution of weights.

Algorithms↗

Tracheal stenting: a better method of dealing with airway obstruction due to thyroid malignancies than tracheostomy.

Tracheostomy remains the primary method of treatment of acute airway obstruction due to malignant invasion and compression of the trachea. However, the development of tracheal stents has provided an alternative effective treatment modality. This case report and literature review highlights the benefits of intra-luminal stenting, including resolution of distressing obstructive symptoms, and subsequent improvement in quality of life.

Aged↗

Combined use of chymosin and protease from Cryphonectria parasitica for control of meltability and firmness of cheddar cheese.

The combined use of chymosin and Cryphonectria parasitica protease was evaluated for manufacturing Cheddar cheese at different chymosin-to-C. parasitica protease ratios of 1:0, 0:1, 67:33, and 33:67. The degree of proteolysis over time was affected by the coagulant type. Proteolysis was thought to be the main cause of changes in functional properties of Cheddar cheeses. The meltability and hardness of cheese made with 100% C. parasitica enzyme was the highest, but it was high in bitterness. The chymosin-to-C. parasitica ratio between 0:1 to 67:33 was found suitable to independently control Cheddar cheese meltability and hardness without a significant level of bitterness.

Ascomycota↗

Comparative immunocytochemistry of isolated rat & monkey pancreatic islet cell types.

BACKGROUND & OBJECTIVES: Data on comparative distribution of the islet cell types in the Indian bonnet monkeys and rats are not available. The aim of the present study was to compare the arrangement of the three islet cell types in the native and in isolated rat and Indian bonnet monkey islets by immunocytochemistry. METHODS: Rat islets isolated by chopped tissue collagenase digestion method and islets of monkey isolated by intraductal collagenase digestion method were immunostained by streptavidin-biotin peroxidase method. RESULTS: Immunocytochemical staining of the isolated islets in both the species revealed the presence of three different cell types: insulin secreting B cells, glucagon secreting A cells and somatostatin secreting D cells. The arrangement of islet cell types in the rats and monkeys was similar to that of the intact islets of the native pancreas but were arranged in a definite pattern. In rats the A and D cells were peripherally arranged around the centrally located B cells. In monkeys the B cells occupied the majority of the periphery while the A and D cells were found mostly in the centre. INTERPRETATION & CONCLUSION: The findings of the present study showed that the arrangement of cell types in the islets was not affected by the isolation procedure. The difference in the arrangement of islet cell types in the two species may reflect special functional adaptations.

Animals↗

Effect of frozen storage on physical properties of pasta filata and nonpasta filata Mozzarella cheeses.

The effects of 1) ripening 2, 7, and 14 d at 7 degrees C before freezing; 2) tempering 7, and 14 d at 7 degrees C after freezing; and 3) frozen storage for 1 and 4 wk at -20 degrees C, on the meltability, stretchability, and microstructure of pasta filata and nonpasta filata Mozzarella cheeses were investigated. Cheeses were cut into 5 x 10 x 7-cm blocks and vacuum-sealed 1 d after manufacture. The results were compared to the corresponding results obtained with unfrozen control samples, aged at 7 degrees C between 2 and 21 d. The changes in physical properties of frozen-stored pasta filata and nonpasta filata Mozzarella cheeses were consistent with critical damage to the cheese microstructure as compared to the unfrozen control samples. Generally, aging before and tempering after freezing resulted in increased meltability of both frozen-stored pasta filata and nonpasta filata Mozzarella cheeses. The stretchability of frozen-stored pasta filata Mozzarella cheese increased during tempering, but that of nonpasta filata Mozzarella cheese decreased during aging and tempering. In most cases, one-week frozen stored pasta filata Mozzarella cheese had higher meltability and stretchability than 4-wk frozen-stored sample. For 1-wk frozen-stored nonpasta filata Mozzarella cheese, the meltability increased but stretchability decreased when it was frozen-stored for 4 wk.

Cheese↗

Determining effects of freezing on pasta filata and non-pasta filata mozzarella cheeses by nuclear magnetic resonance imaging.

The formation of ice during freezing of pasta filata and non-pasta filata Mozzarella cheeses, and the spatial redistribution of water T2 relaxation time and the changes of water self-diffusion coefficient (D) within the unfrozen and frozen-stored cheese samples were observed by nuclear magnetic resonance imaging. Images of water spin number density and water T2 relaxation time were obtained using spin-echo imaging pulse sequence. The water self-diffusion coefficient was measured by pulsed-field gradient spin-echo technique. The ice formation was accompanied by loss of signal intensity in the affected areas of the cheese sample. There was a significant change in T2 and D values of water following freezing-thawing, which can be used to characterize the effect of freezing on cheeses. The D values of the frozen-stored pasta filata Mozzarella cheese samples were higher than those for the unfrozen samples. Such a difference was not observed for the non-pasta filata Mozzarella cheese samples. The T2 distributions of frozen-stored pasta filata Mozzarella cheese samples were narrower, and those for the non-pasta filata Mozzarella cheese samples were broader T2. This may be attributed to the microstructure differences between the two cheeses.

Cheese↗