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Biomedical subjects

R Venkatesh

Publications and source records attributed to R Venkatesh.

At least 19 recordsLinked to original sources
PubMed2005

The effect of age and gender upon symptoms and surgical outcomes in carpal tunnel syndrome.

There is conflicting evidence regarding the effectiveness of carpal tunnel release in older patients. This is a prospective study which evaluates the impact of age and gender upon symptoms, self-reported disability and surgical outcome in a series of 97 patients with carpal tunnel syndrome. Symptom severity, hand function and patient satisfaction were assessed using the Boston Carpal Tunnel Questionnaire and the Patient Evaluation Measure. A statistical correlation of age and gender with symptoms, hand function and surgical outcome was performed with questionnaires administered before open carpal tunnel decompression and 6 months after surgery. Women reported greater pre-operative symptoms and disability than men, but there was no gender-related difference in surgical outcome or patient satisfaction. There was no difference in surgical outcome between patients 60 and 70 years of age and younger patients. The majority of patients over the age of 70 reported an improvement in symptoms and function, but they were less satisfied with their treatment than younger patients. Some patients had problems with persistent numbness and loss of dexterity following surgery. The outcome of carpal tunnel release in terms of improvement in the symptom and functional scores is sufficient to justify surgery in the elderly, but surgical outcomes are less predictable than in younger patients and we recommend that this is explained to them when obtaining consent for surgery.

Adult↗
PubMed2005

Outcomes of high volume cataract surgeries in a developing country.

AIM: To analyse the outcome of high volume cataract surgery in a developing country, community based, high volume eye hospital. METHODS: In a non-comparative interventional case series, the authors reviewed the surgical outcomes of 593 patients with cataract operated upon by three high volume surgeons on six randomly selected days. There were 318 female (54%) and 275 male (46%) patients. Their mean age was 59.57 (SD 10.13) years. The majority of the patients underwent manual small incision cataract surgery (manual SICS). Extracapsular cataract extraction with posterior chamber intraocular lens (ECCE-PCIOL) and intracapsular cataract extraction (ICCE) were also done on a few patients as clinically indicated. RESULTS: Best corrected visual acuity of >or=6/18 was achieved in 94% of the 520 patients who could be followed up on the 40th postoperative day (88% follow up rate). Intraoperative and immediate postoperative complications as defined by OCTET occurred in 11 (1.9%) and 75 (12.6%) patients, respectively. Average surgical time of 3.75 minutes per case (16-18 cases per hour) was achieved. Statistically significant risk factors for outcomes were found to be age >60, sex, and surgeon. CONCLUSION: High volume surgery using appropriate techniques and standardised protocols does not compromise quality of outcomes.

Age Factors↗
PubMed2005

The effect of psychological disturbance on symptoms, self-reported disability and surgical outcome in carpal tunnel syndrome.

In a prospective study, we have evaluated the impact of psychological disturbance on symptoms, self-reported disability and the surgical outcome in a series of 110 patients with carpal tunnel syndrome. Self-reported severity of symptoms and disability were assessed using the patient evaluation measure and the Boston carpal tunnel questionnaire. Psychological distress was assessed using the hospital anxiety and depression scale. There was a significant association between psychological disturbance and the pre-operative symptoms and disability. However, there was no significant association between pre-operative psychological disturbance and the outcome of surgery at six months. We concluded that patients with carpal tunnel syndrome should not be denied surgery because of pre-operative psychological disturbance since it does not adversely affect the surgical outcome.

Adult↗
PubMed2004

Enhanced catalytic and conformational stability of Atlantic cod trypsin upon neoglycosylation.

The applicability of psychrophilic enzymes is limited because of their lower thermodynamic stability in spite of their higher catalytic rate. In this study, we have shown that the thermodynamic stability of the psychrophilic Atlantic cod trypsin could be enhanced appreciably by covalent chemical modification with oxidized sucrose polymer without affecting its hydrolytic activity. The acquired stability of cod trypsin was found to be on par with the mesophilic porcine trypsin.

Animals↗
PubMed2004

Economic cost of cataract surgery procedures in an established eye care centre in Southern India.

PURPOSE: To estimate the direct and indirect costs of three cataract surgery procedures: extracapsular cataract extraction with intra-ocular lens implantation (ECCE-IOL), phacoemulsification (PHACO) and manual small incision cataract surgery (MSICS) using economic costing principles in a well-established eye care programme (Aravind Eye Hospital) in Tamil Nadu, South India during 2000-01. Previous literature suggests that PHACO and MSICS have similar effectiveness. METHODS: The average unit cost for each surgical procedure was calculated from the societal perspective using economic costing methods. Total annual provider's direct costs for each input to surgery were calculated and apportioned appropriately to different cataract surgery techniques using a 'micro-costing approach'. The patient's direct and indirect costs for each procedure were calculated by interviewing staff and patients and by using assumptions about prices for relevant cost items such as transportation, food, medicine, spectacles and economic productivity loss. RESULTS: Average provider's direct costs were highest for PHACO procedures (25.55 US dollars) compared to MSICS (17.03 US dollars) and ECCE-IOL (16.25 US dollars). The difference can be attributed to the cost of equipment and materials. Average direct and indirect patient costs were highest for ECCE-IOL (19.85 US dollars), while the costs for PHACO and MSICS were identical (12.37 US dollars). ECCE-IOL had the highest total costs and MSICS had the lowest total costs from the societal perspective. CONCLUSIONS: Our results suggest that MSICS may have a lower societal cost than other options. Government and NGO hospitals providing cataract surgeries should invest in regular cost analyses, reviews of the literature on effectiveness, and formal cost-effectiveness analyses in order to plan economically efficient interventions. Considering the small incremental cost for providers (less than 1 US dollar), improved outcomes, and lower patient costs, we also believe that MSICS is an important technique to use in efforts to eliminate cataract blindness in India and this result may be generalised to other developing countries.

Cataract Extraction↗
PubMed2002

RecX protein abrogates ATP hydrolysis and strand exchange promoted by RecA: insights into negative regulation of homologous recombination.

In many eubacteria, coexpression of recX with recA is essential for attenuation of the deleterious effects of recA overexpression; however, the molecular mechanism has remained enigmatic. Here, we show that Mycobacterium tuberculosis RecX binds directly to M. tuberculosis RecA as well as M. smegmatis and E. coli RecA proteins in vivo and in vitro, but not single-stranded DNA binding protein. The direct association of RecX with RecA failed to regulate the specificity or extent of binding of RecA either to DNA or ATP, ligands that are central to activation of its functions. Significantly, RecX severely impeded ATP hydrolysis and the generation of heteroduplex DNA promoted by homologous, as well as heterologous, RecA proteins. These findings reveal a mode of negative regulation of RecA, and imply that RecX might act as an anti-recombinase to quell inappropriate recombinational repair during normal DNA metabolism.

Adenosine Triphosphate↗
PubMed1999

Light regime, riboflavin, and pH effects on 2,4-D photodegradation in water.

A laboratory study was conducted to determine the effects of light regime, riboflavin, and pH on photodegradation of 2,4-D in aqueous solution. In controlled-environment chamber experiments, riboflavin sensitized 2,4-D photolysis in a concentration-dependent manner under both attenuated UV (-UV) and enhanced UV (+UV) light regimes. The photolysis half-life of 2,4-D in solutions containing 10 mg L-1 riboflavin was 9.7 and 12.5 h when exposed to +UV and -UV, respectively, compared to no photolysis in the absence of riboflavin. In contrast, the extrapolated half-life of 2,4-D in solutions containing 2.5 mg L-1 riboflavin was 46 h under +UV and 72 h under -UV. The rate of 2,4-D photolysis in the presence of riboflavin increased under both light regimes as initial pH of the solution was decreased from 7.5 to 4.5. The half-life of 2,4-D in the presence of 10 mg L-1 riboflavin at pH 4.5 and exposed to +UV was 1.6 h. Lumichrome, a principal photoproduct of riboflavin, did not photosensitize 2,4-D. Concentrations of 2,4-dichlorophenol formed as a result of riboflavin-sensitized 2,4-D photolysis were higher under the -UV than the +UV regime. These results indicate that riboflavin concentration, solution pH, and light regime are interacting factors that may be manipulated to enhance rates of aqueous 2,4-D photolysis.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1998

Modulation of stability properties of bovine trypsin after in vitro structural changes with a variety of chemical modifiers.

Controlled chemical modification of enzymes, targeting groups not involved in the active site, can lead to modified catalysts that are intrinsically more efficient and resistant to heat and denaturing agents. Bovine pancreatic trypsin was covalently modified up to 75-85% with monomeric glutaraldehyde (MGA), polymeric glutaraldehyde (PGA), oxidized sucrose and oxidized sucrose polymers (OSP 70 and OSP 400). Virtually no loss in activity occurred upon modification. Temperature optima of trypsin shifts from 45-76 degrees C and T50 from 54-76 degrees C for the best modified sample made with OSP. The efficiency of the modifiers in stabilization was ranked in the order: OSP 400-T > OSP 70-T > PGA-T > MGA-T > Sucrose-T. Half-life of modified enzymes also followed the same trend. Both stabilization factor and t1/2 decreased with increasing temperatures. The free energy of activation for inactivation delta(deltaG*) varies from 12-20 kJ/mol and the activation enthalpy delta(deltaH*) of the modified trypsin by 80-120 kJ/mol indicating stabilization. Inactivation of modified trypsin by urea is less noticeable. The character of the two-step inactivation process of trypsin changes with the degree of stabilization in that the duration of phase I one increased noticeably as stabilization increases. Native trypsin fluoresces less intensely showing a red shift under the influence of denaturation. Such a fluorescence change is not so obvious for the modified enzymes indicating conformational stability acquired by modification.

Animals↗
PubMed1998

Retardation of thermal and urea induced inactivation of alpha-chymotrypsin by modification with carbohydrate polymers.

Modification of enzymes by means of covalent coupling using soluble polymers results in enzymes which retain high biological activity and display resistance to denaturants, high temperature and chaotropic agents. Alpha-chymotrypsin, which has a potential for use in industrial applications, was covalently modified by reductive alkylation using polymeric sucrose (OSP, molecular weight 70 and 400 kDa), dextran (73 and 250 kDa) and carboxymethyl cellulose (CMC, approximately 12 kDa). The derivatives retained around 50-80% activity depending on the polymer used and the extent of modification. At the same time, they displayed better thermotolerance than their native counterpart with 4-14 degrees C higher T50 values. During thermal inactivation, both the native and modified enzymes showed biphasic inactivation kinetics. Half-life of modified enzymes were 2-66-fold greater for the first phase and 5-250-fold greater than the native for the second phase of inactivation. The activation free energy of inactivation of alpha-chymotrypsin coupled to polymeric sucrose (400 kDa) was 112.85 kJ/mol for the first phase and 114.71 kJ/mol for the second phase, whereas in the case of the native enzyme, the value for the first phase was 101.55 kJ/mol and 103.42 kJ/mol for the second phase. The activation free energy of inactivation (deltaG*), as well as the activation enthalpy values (deltaH*) of all the modified enzymes were greater than those of the native enzyme, which is an indication of stabilization of the protein and a retardation of inactivation that is usually accompanied by unfolding under thermal and chemical stress. The stability of modified alpha-chymotrypsin is in the following order: OSP 400-C > OSP 70-C > CMC-C > Dextran 73-C = Dextran 250-C.

Carboxymethylcellulose Sodium↗
PubMed1998

Radiation therapy in pseudotumour haemarthrosis.

Total or partial deficiency of factor VIII and IX in the coagulation cascade leads to haemophilia. Haemophilia affecting weight-bearing joints gives a 'pseudotumour' or haemarthrosis-like condition. Surgery and cryoprecipitate infusions have been the treatment for this condition. Radiocolloids and radiation therapy have been used with some benefit. One case of ankle pseudotumour which was treated by low-dose external beam radiation is presented here.

Adolescent↗
PubMed1997

Evaluation of a miniaturized thermal biosensor for the determination of glucose in whole blood.

A miniaturized thermal biosensor has been evaluated as part of a flow-injection analysis system for the determination of glucose in whole blood. Glucose was determined by measuring the heat evolved when samples containing glucose passed through a small column with immobilized glucose oxidase and catalase. Samples of whole blood (1 microliter) can be measured directly, without any pretreatment. The correlation in the response between the thermal biosensor, the Reflolux S meter (Boehringer Mannheim), the Granutest 100 glucose test kit (Merck Diagnostica) and the Ektachem (Kodak) instrument was evaluated. The influence of the hematocrit value and of possible interferences is reported. The correlation measurements show that the thermal biosensor calibrated with aqueous glucose standards generally gives lower values on blood glucose than the reference methods calibrated for serum or blood measurements. Mean negative biases range from 0.53 to 1.16 mmol/l. Differences in sample treatment clearly complicate comparisons and the proper choice of reference method. There was no influence from substances such as ascorbic acid (0.11 mmol/l), uric acid (0.48 mmol/l), urea (4.3 mmol/l) and acetaminophen (0.17 mmol/l) on the response to 5 mmol/l glucose. The hematocrit value does not influence the glucose determination, for hematocrit values of between 13 and 53%.

Biosensing Techniques↗