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Biomedical subjects

P Prakash

Publications and source records attributed to P Prakash.

At least 19 recordsLinked to original sources
PubMed2006

Microincision bimanual phacoemulsification and Thinoptx implantation through a 1.70 mm incision.

PURPOSE: To prospectively assess the efficacy of bimanual phacoemulsification and implantation of Thinoptx, an injectable intraocular lens (IOL), inserted through 1.70 mm clear corneal incision. SETTING: Department of Ophthalmology, Southend Hospital NHS Trust, UK. METHODS: A total of 50 eyes of 49 randomly selected patients with cataracts had microincision clear corneal bimanual phacoemulsification (MICS) with implantation of Thinoptx IOL in the capsular bag. All patients underwent full preoperative assessment. Postoperative assessment was carried out at 3 and 6 weeks and at 15 months. RESULTS: In all 50 cases the IOL was inserted through 1.70 mm clear corneal incision. The mean best-corrected visual acuity was 0.02 (6/6-1) at 6 weeks and was 0.17 (6/10) at the final follow-up. The mean final surgically induced astigmatism at 6 weeks was 0.0106. Coloured haloes around artificial lights were perceived by 69.23% of patients at 6 weeks and by 61.29% at the final follow-up. One patient underwent IOL exchange for this. Posterior capsular opacification was noticed in 31.26% at 6 weeks and in 64.51% at 15 months. Anterior capsular opacification was noticed in 5.26% at 6 weeks and in 16.12% at 15 months. In one patient the IOL had to be exchanged because of tilt and displacement of the IOL due to anterior capsular phimosis. CONCLUSIONS: We conclude Thinoptx can be safely inserted through 1.70 mm incision used for bimanual phacoemulsification. Distance and near visual acuity achieved with this IOL is satisfactory. There is no significant change in keratometric astigmatism following this procedure. However, posterior capsular opacification rate was significantly higher with this IOL. Haloes around light sources were significant.

Cataract↗
PubMed2005

Therapeutic uses of Ocimum sanctum Linn (Tulsi) with a note on eugenol and its pharmacological actions: a short review.

The medicinal plants are widely used by the traditional medical practitioners for curing various diseases in their day to day practice. In traditional systems of medicine, different parts (leaves, stem, flower, root, seeds and even whole plant) of Ocimum sanctum Linn (known as Tulsi in Hindi), a small herb seen throughout India, have been recommended for the treatment of bronchitis, bronchial asthma, malaria, diarrhea, dysentery, skin diseases, arthritis, painful eye diseases, chronic fever, insect bite etc. The Ocimum sanctum L. has also been suggested to possess antifertility, anticancer, antidiabetic, antifungal, antimicrobial, hepatoprotective, cardioprotective, antiemetic, antispasmodic, analgesic, adaptogenic and diaphoretic actions. Eugenol (1-hydroxy-2-methoxy-4-allylbenzene), the active constituent present in Ocimum sanctum L., has been found to be largely responsible for the therapeutic potentials of Tulsi. Although because of its great therapeutic potentials and wide occurrence in India the practitioners of traditional systems of medicine have been using Ocimum sanctum L. for curing various ailments, a rational approach to this traditional medical practice with modern system of medicine is, however, not much available. In order to establish the therapeutic uses of Ocimum sanctum L. in modern medicine, in last few decades several Indian scientists and researchers have studied the pharmacological effects of steam distilled, petroleum ether and benzene extracts of various parts of Tulsi plant and eugenol on immune system, reproductive system, central nervous system, cardiovascular system, gastric system, urinary system and blood biochemistry and have described the therapeutic significance of Tulsi in management of various ailments. These pharmacological studies have established a scientific basis for therapeutic uses of this plant.

Animals↗
PubMed2002

Multiple coronary risk factors in healthy older Kuwaiti males.

OBJECTIVE: The objective was to examine the percentage and severity of obesity and some common biochemical coronary heart disease (CHD) risk factors in a sample of healthy Kuwaiti adult males > or =45 y of age. We also sought to determine the percentage of males at increased risk due to the presence of multiple CHD risk factors. DESIGN: The study was a cross-sectional study. SETTING: The study was conducted in all men who underwent a mandatory job related physical examination or who sought to obtain retirement benefits. SUBJECTS: A total of 740 healthy Kuwaiti males between the ages of 45 to 80 y. RESULTS: In all, 37% of the men were obese, 26% had elevated glucose values and 52% had elevated or high cholesterol levels. Some had multiple risk factors for CHD, including age > or =45 y, obesity, male gender, hyperglycemia and hypercholesterolemia. Blood glucose values increased consistently from younger (45-54 y) to older age groups (55-64 and > or =65 y). Blood glucose values varied inversely with education level. CONCLUSIONS: In societies with relatively uniform income levels, educational level may be a better indicator of chronic disease risk than income per se. These results, showing a high percentage of men with several risk factors and high mean values, suggesting more severe risk, suggest that immediate action should be taken to develop a public health intervention strategy to educate Kuwaiti men to become aware of the causes and correlates of CHD and how to decrease their risk for CHD and heart attack, the leading cause of death in Kuwait.

Aged↗
PubMed2001

Prevalence of coronary risk factors in healthy adult Kuwaitis.

Obesity has been shown to be a serious health risk and is associated with a wide range of comorbid conditions, including diabetes mellitus, coronary heart disease (CHD), gall bladder disease, hypertension, osteoarthritis, and certain cancers. Studies in Kuwait and other Gulf States indicate that obesity is prevalent and may be increasing. Previous studies in Kuwait have mostly focused on the epidemiology of overweight and obesity in children, adolescents, and young adults. Relatively less is known about the prevalence of overweight and obesity and its correlates in older adults for whom obesity may be more closely related to CHD risk. The purpose of this study was to examine the prevalence of overweight and obesity in 9755 adult men and women and to determine the relationship of weight to other risk factors for chronic disease. For the first time we examine a sample of older Kuwaitis to explore the relationship between high BMI, hypercholesterolemia and hyperglycemia. One-third of adult Kuwaitis are obese (BMI > 30 kg/m2), 4.7% of Kuwaiti females have severe obesity (BMI > 40 kg/m2). BMI, cholesterol, and glucose values increase with age across the life span. Older Kuwaitis have a greater constellation of risk factors for chronic diseases. The results of a multiple linear regression model in which cholesterol values were studied, controlling for age, BMI, blood glucose, and sex revealed that age, BMI and sex were significant predictors of cholesterol values. These results indicate that actions to reduce obesity, hypercholesterolemia, and hyperglycemia are needed.

Adult↗
PubMed2001

In vitro inhibition of proliferation of estrogen-dependent and estrogen-independent human breast cancer cells treated with carotenoids or retinoids.

Both estrogen-receptor (ER) positive MCF-7 and ER-negative Hs578T and MDA-MB-231 human breast cancer cells were treated with carotenoids (beta-carotene, canthaxanthin and lycopene) and retinoids (all-trans-, 9-cis- and 13-cis-retinoic acid and all-trans-retinol). Among carotenoids, beta-carotene significantly reduced the growth of MCF-7 and Hs578T cells, and lycopene inhibited the growth of MCF-7 and MDA-MB-231 cells. Canthaxanthin did not affect the proliferation of any of the three cell lines. All-trans- and 9-cis-retinoic acid significantly reduced the growth of both MCF-7 and Hs578T cells, whereas 13-cis-retinoic acid and all-trans-retinol had a significant effect only on MCF-7 cells. MCF-7 and Hs578T cells treated with all-trans-retinoic acid (all-t-RA) were further studied for the mechanism behind growth inhibition. Retinoic acid receptors alpha and gamma (RARalpha, gamma) in MCF-7 cells and RARalpha, beta and gamma in Hs578T cells were not induced by all-t-RA treatment at either the protein or mRNA level. Hs578T cells treated with all-t-RA had significantly more cells in the G0/G1 stage of the cell cycle, but the same was not observed for MCF-7 cells. All-t-RA induced a dose-dependent cell death in MCF-7 cells, which may be a necrotic phenomenon. These results demonstrate that ER status is an important, although not essential factor for breast cancer cell response to carotenoid and retinoid treatments, and the mode of action of all-t-RA in MCF-7 and Hs578T cells is not through the induction of RAR. Other mechanistic pathways that are either followed by or concomitant with growth inhibition are possible.

Antioxidants↗
PubMed2000

Retinoids, carotenoids, and human breast cancer cell cultures: a review of differential effects.

Cancer of the breast is the most common incident cancer and cause of death from cancer in women. Several epidemiologic studies have reported a significant inverse relationship between the intake of vitamin A and/or provitamin A-rich foods and the incidence of certain cancers, including breast cancer. A large number of studies have been conducted to determine the effect of retinoids (all-trans-retinoic acid, in particular), and to a lesser extent of carotenoids, on breast cancer using cell culture models. In general, the results of these studies demonstrate beneficial effects of all-trans-retinoic acid on different breast cancer cells. This review compares studies conducted in different laboratories using retinoids and carotenoids as treatments for breast cancer cells and suggests what may be the underlying reasons for the differential effects of these compounds on the same cell lines.

Breast Neoplasms↗
PubMed2000

Frequency- and time-dependent effects of fendiline on action potentials of guinea pig papillary muscle.

The action of fendiline on cardiac electrical activity was investigated in guinea pig papillary muscle by monitoring frequency- and time-dependent changes in membrane potential, action potential (AP) configuration and conduction velocity. Isolated guinea pig papillary muscles driven at 0.1 to 3 Hz showed a concentration-dependent reduction of +Vmax, overshoot, and AP duration at -20mV (APD20) in the presence of fendiline (1-320 microM), reflecting inhibition of Na+ and L-type Ca2+ channels, respectively. No significant change in resting potential and AP duration at 90% repolarization (APD90) were observed. Inhibition of +Vmax and APD20 was more prominent at higher frequency of stimulation (2 Hz) than at lower ones (0.2 Hz), demonstrating frequency-dependent block of Na+ and Ca2+ channels including an open channel block. A good relationship between changes in +Vmax and APD20 suggested some commonality in the mechanism of inhibition of Na+ and Ca2+ channels by fendiline. Time-dependence of effects of fendiline, observed in presence of bolus dose (200 microM), showed an earlier onset of inhibition of +Vmax and APD20, particularly at higher frequencies. Missed beats and conduction block also appeared earlier in preparations driven at higher frequency. These findings suggest a frequency-dependent (and open channel) block of Na+ and Ca2+ channels by fendiline, leading to inhibition of fast and slow conduction in addition to its reported inactivated Ca2+ channel block.

Action Potentials↗
PubMed1999

Subcellular accumulation of beta-carotene and retinoids in growth-inhibited NCI-H69 small cell lung cancer cells.

Delivery of beta-carotene in tetrahydrofuran slowed the growth of NCI-H69 small cell lung cancer cells. Analysis of cells and cellular fractions revealed that beta-carotene-treated cells accumulated beta-carotene as well as some polar metabolites, primarily in the crude nuclei. Cells were grown at 1 x 10(5) cells/ml and treated with 20 microM beta-carotene. Growth monitoring up to 15 days indicated an inverse relationship between the duration of beta-carotene treatment and the rate of cell growth. Reverse-phase high-performance liquid chromatography analysis of treated cells showed the presence of beta-carotene, retinoic acid, retinol, and retinal, with beta-carotene accounting for the major material recovered. When cellular fractions were analyzed for beta-carotene, it was found to be located primarily in the crude nuclei. These results demonstrate that treatment of small cell lung cancer cells with beta-carotene results in a reduced growth of the cells. Further investigation is required to show a direct effect of beta-carotene or its intracellular polar metabolites on these cells. Accumulation of beta-carotene in the nucleus suggests a need for evaluating the nuclear role for beta-carotene.

Antioxidants↗
PubMed1999

Squint--what to do and when.

Squint is unfortunately a neglected subject in our country. It is considered only a cosmetic problem without realising that any manifest squint is a one eyed blindness which results in lack of binocular vision. Consequently there is no stereopsis. The management should be undertaken at the earliest possible age when development of uni-ocular as well as binocular vision is taking place. Once the visual system is mature, only cosmetic appearance can be improved, but not the vision.

Age Factors↗
PubMed1998

Preparation by differential gradient centrifugation is better than swim-up in selecting sperm with normal morphology (strict criteria).

OBJECTIVE: To evaluate two commonly used methods of sperm preparation with respect to their effects on sperm morphology (strict criteria). DESIGN: Auto-controlled, split sample study performed on the semen of 74 male partners of couples enrolled for IVF. SETTING: In vitro fertilization and andrology laboratories at a tertiary care, major teaching hospital. PATIENT(S): Seventy-four male partners of couples who were scheduled to undergo IVF. INTERVENTION(S): Equal halves of the same semen sample were evaluated for strict criteria sperm morphology before and after preparation by differential gradient centrifugation using Percoll (Pacific Andrology, Montrose, CA) and by the standard swim-up method. MAIN OUTCOME MEASURE(S): The percentage of morphologically normal sperm was assessed using strict criteria before and after the two methods of sperm preparation. Specific parameters studied were individual abnormalities of the head, midpiece, and tail. RESULT(S): Sperm preparation using differential gradient centrifugation with Percoll produced a significantly greater number of specimens with normal sperm morphology and also showed higher absolute quantitative improvement over the swim-up method. The two methods were comparable in regard to their effects on specific sperm abnormalities (i.e., head, midpiece, and tail defects). CONCLUSION(S): The differential gradient sperm separation method using Percoll is superior to the swim-up method for selecting sperm with normal morphology as assessed by strict criteria. Because sperm morphology as assessed by strict criteria is a good predictor of oocyte fertilization, this method can be recommended as the method of choice for assisted reproductive technology laboratories. Use of this method may help improve outcome by increasing fertilization rates.

Centrifugation, Density Gradient↗
PubMed1998

Superoxide anion radical generation as a temperature stress response in the gills of freshwater catfish Heteropneustes fossilis: role in mucus exudation under elevated temperature.

Temperature induced superoxide anion radical (O2-) generation in vivo has been demonstrated in the gills of Heteropneustes fossilis by electron spin resonance (ESR) spin trapping. Temperature exposures from 25 degrees C to 37 degrees C for various times (1-4 hr) caused generation of O2- in the gill. The acid mucopolysaccharide test was conducted in gill sections during elevated temperatures. The results showed an increased activity of mucopolysaccharide in gills which indicate an increased mucus secretion in gills during elevated temperatures. The detectable stable levels of O2- in the gill at 32 and 37 degrees C temperature exposures point towards a probable role for this radical in the exudation of mucus under elevated temperature.

Animals↗
PubMed1998

Influence of a melatonin implant on the free radical load in avian thyroid and its relation with thyroid hormonogenesis.

The primary aim of this study was to evaluate the effect of melatonin on the oxiradical load in avian thyroid. The superoxide free radicals have been spin trapped by EPR spectroscopy in the thyroid gland of Indian rock pigeon Columbia livia following melatonin implantation for two weeks. Melatonin implantation resulted in augmentation in the levels of superoxide radical in the thyroid gland of pigeons with a concomitant decrease in the levels of the total superoxide dismutase activity. This was also associated with increased lipid peroxidation. Melatonin implantation caused a significant increase in plasma levels of glucose. Plasma levels of thyroxine (T4) and triiodothyronine (T3) were lower in the melatonin-treated pigeons. However, the T3/T4 ratio was higher following melatonin implantation. Since iodination of tyrosine is an H2O2-dependent phenomenon, the inhibition in the activity of SOD could lead to impaired thyroid hormone synthesis.

Animals↗
PubMed1998

Verapamil and TTX inhibit +Vmax but differentially alter the duration of action potential of adult chicken ventricular myocardium.

Verapamil, a Ca2+ channel blocker, is also reported to block Na+ channels in mammalian heart and to modulate the repolarisation phase of cardiac action potential (AP). The Na+ channel blocking activity of verapamil and its implication to changes in repolarisation were studied on chicken ventricular strips where upstroke is due to highly TTX sensitive Na+ channels. At low doses verapamil (0.5-5 micro M) and TTX (0.1-0.5 nM) did not cause any significant effect on resting membrane potential (Em), maximal upstroke velocity (+Vmax) or AP duration (ADP). Higher concentrations of both verapamil (10-320 micro M) and TTX (1-40 nM) caused dose-dependent decrease in +Vmax and overshoot (Eov) without any change in Em. EC50 for the inhibitory effect of verapamil and TTX on +Vmax was 140 microM and 14 nM respectively. Na+ channels in adult chicken ventricular myocardium, therefore, seem to be more sensitive to TTX than their mammalian counterpart. Higher dosage of verapamil are needed to block Na+ channels in adult avian heart as reported for mammalian myocardium. Both verapamil and TTX caused dose-dependent changes in APD at-20 mV (ADP20) and at 90% repolarisation (APD90). TTX (1-40 nM) produced a decrease of 5-13% in APD20 and 4-12% in APD90 indicating a uniform hastening of the repolarisation process. Verapamil (10-320 micro M), however, induced 6-38% decrease in APD20 but 5-12% increase in APD90. Regression analysis of the relationship between changes in +Vmax and APD20 and APD90 in presence of TTX and verapamil exhibit significant linear correlation r for APD20 and APD90, being +0.965 for TTX and +0.978 and-0.898 for verapamil respectively. A linear correlation between inhibition of +Vmax and reduction in APD for TTX indicates the possibility that Na+ channel linked mechanism(s) underlie repolarisation process. Verapamil induced decrease in APD20 and increase in APD90 could be explained by the block of Na+/Ca2+ and K+ channels respectively.

Action Potentials↗
PubMed1997

A simple synthetic liquid medium for development of yeast and mycelial form of pathogenic species of Candida.

Thirty two known strains of Candida species were used for evaluation of glucose, serine, ornithine, methionine, GSOM medium and its comparison with Lee's medium for the production of yeast and mycelial phase at different temperatures and on prolonged incubation. No mycelial form was observed when various Candida species in GSOM and Lee's medium were incubated at 25 degrees C up to 72 hours. Percentage of mycelial forming cells of Candida species were more in GSOM medium than Lee's medium in 48 hours at 37 degrees C. Among various species of Candida, albicans and C. parapsilosis showed maximum mycelium formation. GSOM medium can be used for growing Candida species particularly C. albicans in mycelial phase.

Candida↗
PubMed1997

Torsional changes in surgery for A-V phenomena.

The role of torsion in the aetiopathogenesis of A-V phenomena has not been sufficiently emphasized. The success of vertical displacement of horizontal recti in correction of A or V has not been attributed to torsional changes. To evaluate this aspect, 21 cases of A or V phenomena were subjected to monocular recession-resection procedure with vertical shifting. Preoperative and postoperative torsional changes were evaluated on synoptophore (subjective torsion), and confirmed by fundus photography (objective torsion). Intorsion with A phenomenon was seen preoperatively in 5 of 8 cases which increased after surgery and was seen postoperatively in the other 3 cases also. Extorsion was observed in 5 of 13 cases pre operatively in 'V' phenomenon, but the changes in extorsion after surgery were less dramatic than those in intorsion. The oblique overactions were reduced in cases where they were present. Correction of A-V phenomena by torsion induced by vertical shifting of horizontal recti muscles is proposed, highlighting the role of torsion in A-V phenomena.

Follow-Up Studies↗
PubMed1997

Randot stereoacuity at various binocular combinations of Snellen acuity.

Binocular combinations of Snellen acuity were varied from 6/60 to 6/6 in standard steps in twenty normal adults and Randot stereoacuity was measured at each level. Using the 560 unique stereoacuity scores thus obtained, a nomogram was constructed which provides expected stereoacuity scores at all unique binocular combinations of Snellen acuity. It was seen that there is a linear correlation between binocular isoacuity (at level 6/36 or better) and Randot stereoacuity.

Adolescent↗
PubMed1996

Developmental changes in Ca(2+)-uptake, Na+,Ca(2+)-exchange and Ca(2+)-ATPase in freshly isolated embryonic, newborn and adult chicken heart.

Developmental changes in cellular Ca(2+)-transport mechanisms were studied in chick heart by determining cellular Ca(2+)-uptake and Na+,Ca(2+)-exchange activity in freshly isolated ventricular tissues of embryonic (5-18 days old), newborn (1-2 days old) and young adult (90-100 days old) heart by monitoring 45Ca influx. Ca(2+)-ATPase activity was determined in microsomal fractions at different stages of development. The Ca(2+)-uptake (per g wet tissue weight) increased with the development of embryonic as well as post-hatch chick heart, reaching a maximum in the young adult chicken. The overall increase in Ca(2+)-uptake, from embryonic day 5 to young-adult stage, was more than 3 fold. The Na+,Ca(2+)-exchange activity, determined as Na(+)-gradient-induced Ca(2+)-uptake in presence of either ouabain or zero [Na+]0, showed a 6-fold increase during development of heart from the embryonic day 5 to the young adult stage. Amiloride, an inhibitor of Na+,Ca(2+)-exchange, caused a dose-dependent reduction in a ouabain-induced rise in 45Ca influx at different stages of development. The inhibitory effect of amiloride was, however, greater during later stages of development. A progressive increase in Ca(2+)-ATPase activity was also seen during development. Ca(2+)-ATPase exhibited about a 4-fold increase in activity from embryonic day 7 to the young adult. The concomitant increase in Ca(2+)-uptake, Na+,Ca(2+)-exchange and Ca(2+)-ATPase activities suggests age-dependent changes in Ca(2+)-transport and storage systems of developing heart during embryogenesis and post-embryonic life. During embryogenesis the developmental increase in Na+,Ca(2+)-exchange activity was greater than that during post-hatch development of heart. However, the increase in Ca(2+)-ATPase activity was greater during post-hatch development than during embryogenesis. It is suggested that Na+,Ca(2+)-exchange and Ca(2+)-ATPase play a prominent role in maintaining cellular Ca2+ homeostasis during embryogenesis and after hatching.

Animals↗