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Biomedical subjects

R Swaminathan

Publications and source records attributed to R Swaminathan.

At least 37 records · Page 2Linked to original sources
PubMed2003

Evidence of altered bone turnover, vitamin D and calcium regulation with knee osteoarthritis in female twins.

BACKGROUND: Osteoarthritis (OA) is a disorder of the whole synovial joint organ. There is growing evidence of the importance of bone turnover in OA, and human studies have demonstrated that the subchondral bone is metabolically active in OA. The aim of this study was to assess the relationships of radiographic knee OA with altered bone turnover and calcium regulation. METHODS: We performed a matched and unmatched case-control study using twins assessed for OA. The subjects were 1644 female Caucasian twin pairs (266 monozygotic and 556 dizygotic) aged 24-79 yr from the St Thomas' UK Adult Twin Registry. Assays for measures of bone turnover [bone-specific alkaline phosphatase, osteocalcin and urinary deoxypyridinoline (DPD)] and calcium regulation [serum parathyroid hormone (PTH), 25-hydroxyvitamin D, serum calcium, serum magnesium and serum phosphate] were performed. The radiological features of knee OA were graded on a four-point scale (0-3) for osteophytes and a five-point scale (0-4) for Kellgren and Lawrence classification. Adjustment for age, body mass index (BMI) and relatedness was made. Conditional logistic regression analysis was also used to estimate the odds ratio (OR) and 95% confidence intervals (CI) for having radiological features of knee OA per standardized unit difference of serum variable between twins. RESULTS: Of the 1644 women studied, 474 (28.8%) had radiological evidence of knee osteophytes. There was evidence of increased bone turnover, increased PTH levels and decreased vitamin D levels in this group compared with those without osteophytes. No association was seen with joint space loss. After adjusting for age, BMI and relatedness, all of the differences disappeared except for a significant increase 10% in urinary DPD (P = 0.04). Discordant twin pair analysis (performed on a subgroup of 229 pairs) confirmed modest increases in bone resorption indicated by urinary DPD (OR 1.67, 95% CI 0.88-3.16) and a significant decrease in serum magnesium (OR 0.65, 95% CI 0.46-0.92) in the co-twins with OA. CONCLUSION: Bone resorption is increased in women with knee OA, consistent with metabolically active subchondral bone. However, bone formation, vitamin D and calcium regulation were not different after adjusting for age and BMI. The results suggest that bone resorption is increased in the presence of OA. Although we cannot clearly differentiate a cause or effect relationship, these results suggest that this is related to disease mechanisms and point to potential diagnostic or therapeutic avenues for bone resorption in OA.

Adult↗
PubMed2002

Genetic contribution to renal function and electrolyte balance: a twin study.

A classical twin study was performed to assess the relative contributions of genetic and environmental factors to serum levels of calcium, phosphate and magnesium, urinary levels of calcium, sodium and potassium, and creatinine clearance. The subjects were 1747 adult female twin pairs: 539 monozygotic and 1208 dizygotic. The intraclass correlations were calculated, and maximum-likelihood model fitting was used to estimate genetic and environmental variance components. The intraclass correlations for all of the variables assessed were higher in monozygotic twin pairs. The heritabilities (with 95% confidence intervals) obtained from model fitting were: serum calcium, 33% (21-45%); serum phosphate, 58% (53-62%), serum magnesium, 27% (15-39%); 24 h urinary potassium, 40% (27-51%); 24 h urinary calcium, 52% (41-61%); 24 h urinary sodium, 43% (30-54%); fractional excretion of sodium, 52% (44-59%); serum creatinine, 37% (25-49); calculated creatinine clearance, 63% (54-72%). This study provides evidence for the importance of genetic factors in determining urinary and blood levels of the major electrolytes involved in blood pressure regulation. Identifying heritability is the first step on the way to finding specific genes, which may improve our insight into the pathophysiology of the metabolism of these electrolytes, and thereby improve our understanding of the aetiology of complex diseases such as renal failure and hypertension.

Adolescent↗
PubMed2002

Size at birth, adult intestinal calcium absorption and 1,25(OH)(2) vitamin D.

BACKGROUND: Adult bone mineral status is modified by early environmental influences, but the mechanism of this phenomenon is unknown. Intestinal calcium absorption and vitamin D metabolism are integrally involved in bone metabolism and may be programmed during early life. AIM: To examine the early-life influences on calcium absorption and its control in 322 post-menopausal female twins. METHODS: Intestinal calcium absorption was assessed by the stable strontium (Sr) method. Serum PTH, 25(OH) and 1,25(OH)(2) vitamin D were measured and recalled birth weight recorded. RESULTS: Fractional intestinal Sr absorption (alpha Sr) was correlated with serum 1,25(OH)(2) vitamin D (p<0.001), but not with 25(OH) vitamin D. Birth weight was inversely associated with serum 1,25(OH)(2) vitamin D (p=0.04), the association being independent of serum calcium, phosphate, creatinine and PTH. Birth weight was inversely correlated with alpha Sr (p=0.03), this association being independent of age, season, customary calcium intake and serum 25(OH) vitamin D; however, when serum 1,25(OH)(2) vitamin D was added into the model, the association became non-significant, suggesting that the association was partially mediated via serum 1,25(OH)(2) vitamin D. DISCUSSION: We found a significant inverse association between birth weight and intestinal calcium absorption that is partially explained by an association between serum 1,25(OH)(2) vitamin D and birth weight. This suggests a mechanism whereby the intra-uterine environment might affect adult skeletal status.

Aged↗
PubMed2002

Effect of acute glycaemic index on clinical outcome after acute stroke.

Studies have shown that hyperglycaemia acutely after stroke independently predicts poorer survival and independence. Whether the change in glycaemic index in the acute phase of stroke has any effect on stroke outcome is unclear. Glycated serum proteins (GSP) reflect blood glucose concentration during the preceding 2 weeks. The aim of this study is to measure the association between the change in GSP % in the first 2 weeks after stroke and outcome. 167 patients were included. 117 (70%) patients were alive at 3 months. Admission glucose was higher in dead patients (7.8 mmol/l) compared to survivors (6.6 mmol/l) (p < 0.01). GSP at day 14 was higher in non survivors (21.8%) compared with survivors (19.1%) (p < 0.0001) as was the change in GSP (2.0 %) in non survivors compared with survivors (0.1%) (p < 0.0001). After adjusting for case mix, the change in GSP % was significantly associated with stroke mortality (p = 0.04). The odds ratio for death at 3 months after stroke associated with every 1% increase in change between GSP day 14 and GSP day 0, was 1.28 (95% CI: 1.1-1.62). Increases in glycaemic index as determined by GSP % are associated with excess in stroke mortality after adjusting for case mix. Intervention trials are required to test the hypothesis that improving glycaemic index after acute stroke improves outcome.

Aged↗
PubMed2001

The effect of season and vitamin D supplementation on bone mineral density in healthy women: a double-masked crossover study.

Vitamin D status is known to be an important determinant of bone mineral density (BMD). There is a significant seasonal variation in serum vitamin D, and some studies have reported an associated seasonal variation in BMD. The present study was devised to investigate whether a seasonal variation in BMD could be detected in healthy normal subjects, along with associated variations in serum parathyroid hormone (PTH), intestinal calcium absorption and biochemical markers of bone turnover. A second aim was to investigate whether, if such variations were identified, they could be suppressed by vitamin D supplementation. The subjects were 70 healthy female volunteers (mean age 47.2 years, range 24-70 years) recruited into a double-masked crossover study and followed over 2 years. During the first year 35 subjects received a daily oral supplement containing 800 IU (20 micrograms) cholecalciferol (group 1) and 35 subjects received a placebo preparation (group 2). During the second year the treatment each group received was reversed. Lumbar spine (L1-L4), left proximal femur and total body BMD were measured by DXA at 3-month intervals. Serum 25-hydroxyvitamin D (25-OHD), serum PTH, bone markers (bone-specific ALP (BSAP) and urinary crosslinks (DYPD/creatinine)) and calcium absorption were also measured at each visit. Cholecalciferol treatment increased serum 25-OHD by 25.4 nmol/l (p < 0.001), while a reciprocal decrease in serum PTH of 6.6 ng/l (p = 0.011) was seen in subjects in the lowest quartile of baseline serum 25-OHD. The treatment had no significant effect on spine, femur or total body BMD, calcium absorption or bone markers. When Fourier analysis was used to analyze the data for seasonal effect (defined as twice the amplitude of the 1-year period variation) a highly significant effect for 25-OHD of 18 nmol/l (p < 0.001) was found. However, no effect was found for BMD, PTH, calcium absorption or bone markers. The analysis set a 95% confidence limit to the seasonal effect of less than 0.6% for spine, total hip and total body BMD. It was concluded that in the population of healthy women studied there was no evidence of seasonal variation in spine, femur or total body BMD, serum PTH, calcium absorption or bone markers. Vitamin D supplementation was found to have no effect on BMD.

Adult↗
PubMed2001

Biochemical markers of bone turnover.

BACKGROUND: Osteoporosis in many countries has reached epidemic proportions. This has stimulated the development of biochemical markers to assist in the assessment of osteoporotic risk and in monitoring the efficacy of treatment. Biochemical markers of bone turnover are products released from osteoblasts and osteoclasts or collagen breakdown products. MARKERS: Markers of bone formation include bone-specific alkaline phosphatase (BAP), osteocalcin (OC) and procollagen peptides. All of these can be measured easily by immunoassay techniques. Of these markers, OC has been extensively studied. However, OC undergoes in vitro degradation, thus, assay results are variable. BAP, on the other hand, is much more stable and shows less within-person biological variation. Bone resorption markers include tartrate-resistant acid phosphatase (TRAP) and collagen breakdown products, such as pyridinium cross-links, galactosyl hydroxylysine and cross-linked telopeptides, such as CTx and NTx. Of these, deoxypyridinium (DPD) has been extensively studied. DPD shows diurnal variation and the within-individual biological variation is large. Of the newer assays, NTx appear to show large differences at menopause. CONCLUSIONS: Thus, serum BAP and DPD or NTx are the current choice of bone markers.

Alkaline Phosphatase↗
PubMed2001

Population-based survival from colorectal cancer in Mumbai, (Bombay) India.

Survival estimates of patients registered by population-based cancer registries reflect the average prognosis from a given cancer as they are based on unselected patients with a wide range of natural histories and treatment patterns. In this paper, we report the survival experience of colorectal cancer patients in Mumbai (Bombay), India. Follow-up information on 1642 colorectal cancer patients registered by the Bombay Population-based Cancer Registry for the period 1987-1991 was obtained by matching with death certificates from the Bombay vital statistics registration system, postal/telephone enquiries, home visits and scrutiny of medical records. Cumulative observed and relative survival proportions were calculated by Hakulinen's method. For comparison of results with other populations, age-standardised relative survival (ASRS) was calculated by directly standardising age-specific relative survival to the specific age distributions of the world standard cancer patient population in 1985. The log-rank test was used to identify the potential prognostic variables which were introduced step-wise into a Cox regression model to identify the independent predictors of survival. The 5-year relative survival was 36.6% for colon and 42.2% for rectal cancer. Age, site of cancer and clinical stage of disease emerged as independent predictors of survival. Age-specific 5-year relative survival declined with advancing age. Survival at 5 years was 61.2% for localised colon cancer; 31.9% for regional and 9.0% for distant metastatic disease. These were 65.7, 25.6 and 4.3%, respectively for rectal cancers. Comparison of the results with other populations revealed significant variations, which seem to be related to differences in detection and treatment. The prognosis from colorectal cancer in Mumbai and developing countries, may be further improved through early detection linked with treatment.

Adolescent↗
PubMed2001

Platelet Na,K-adenosine triphosphatase as a tissue marker of hyperthyroidism.

Platelet Na(+),K(+)-adenosine triphosphatase (ATPase) activity was measured in 34 (15 males, 19 females) healthy subjects, 89 (35 males, 54 females) hyperthyroid patients, and 34 (7 males, 27 females) treated hyperthyroid patients to assess the potential of this measurement as a tissue marker and diagnostic test for hyperthyroidism. Platelet Na(+),K(+)-ATPase activity was measured in platelet lysates by the rate of release of phosphate from adenosine triphosphate (ATP) in the presence and absence of ouabain. Platelet Na(+),K(+)-ATPase activity (median and range) in the hyperthyroid group (271, 169 to 821 pmol/h/g protein) was significantly higher compared with the healthy group (125, 74 to 185 micromol/h/g protein, P <.001 by Mann-Whitney U test). The treated hyperthyroid group had slightly, but significantly higher, free triiodothyronine (FT3) and free thyroxine (FT4), as well as platelet Na(+),K(+)-ATPase activity (147, 98 to 246 micromol/h/g protein, P <.05). If a platelet Na(+),K(+)-ATPase activity of 190 micromol/h/g protein was used as a cut off value, the specificity and sensitivity were 90% and 93%, respectively. We conclude that platelet Na(+),K(+)-ATPase may be a useful tissue marker of hyperthyroidism.

Adolescent↗
PubMed2001

Washing of marine coastal sand in a batch reactor: sorption and desorption of BTEX.

This study addresses the issues related to decontamination of marine beach sand accidentally contaminated by petroleum products. Sorption and desorption of BTEX (i.e., benzene, toluene, ethylbenzene, and xylene) onto the sand from Uran Beach, located near the city of Mumbai, India, were studied, and isotherms were determined using the bottle point method to estimate sorption coefficients. Alternatively, QSARs (i.e., quantitative structure activity relationships) were developed and used to estimate the sorption coefficients. Experiments for kinetics of volatilization as well as for kinetics of sorption and desorption in the presence of volatilization were conducted in a fabricated laboratory batch reactor. A mathematical model describing the fate of volatile hydrophobic organic pollutants like BTEX (via sorption and desorption in presence of volatilization) in a batch sediment-washing reactor was proposed. The experimental kinetic data were compared with the values predicted using the proposed models for sorption and desorption, and the optimum values of overall mass transfer coefficients for sorption (K(s)a(s)) and desorption (K(d)a(d)) were estimated. This was achieved by minimization of errors while using the sorption coefficients (Kp) obtained from either laboratory isotherm studies or the QSARs developed in the present study. Independent experimental data were also collected and used for calibration of the model for volatilization, and the values of the overall mass transfer coefficient for volatilization (K(g)a(g)) were estimated for BTEX. In these exercises of minimization of errors, comparable cumulative errors were obtained from the use of Kp values derived from experimental isotherms and QSARs.

Adsorption↗
PubMed2001

Dimethylarginines in chronic renal failure.

BACKGROUND: Nitric oxide (NO) is a potent chemical mediator involved in many functions. In vivo production of NO is thought to be regulated by endogenous analogues of L-arginine: asymmetric dimethylarginine (ADMA). AIM: To examine the effect of renal function and dialysis on the serum concentrations of ADMA and symmetric dimethylarginine (SDMA). METHODS: Blood samples were obtained from nine healthy subjects, patients with renal failure before (n = 17) and after haemodialysis (n = 9), nine patients on chronic ambulatory peritoneal dialysis (CAPD), and 13 patients with chronic renal failure on conservative treatment. Serum samples were extracted using a solid phase cation exchange column and the extracts were analysed by high performance liquid chromatography (HPLC). RESULTS: Serum concentrations of ADMA in patients with renal failure (mean, 1.04 micromol/litre; SD, 0.17) were significantly higher than those of controls (mean, 0.61 micromol/litre; SD, 0.13). Haemodialysis significantly decreased the serum concentration by 36% (before dialysis: mean 0.99 (SD, 0.25) micromol/litre; after dialysis: mean, 0.63 (SD, 0.15) micromol/litre). Serum SDMA concentrations were higher in patients with renal failure, and haemodialysis decreased the concentration by 60%. There was no difference in serum arginine concentrations between the groups. CONCLUSION: Serum concentrations of ADMA are increased in renal failure and haemodialysis reduces the concentration.

Adult↗
PubMed2001

Study for reclamation of land occupied by solar evaporation pond at UCIL, Bhopal, India.

Solar Evaporation Ponds (SEP) were used by Union Carbide India Limited (UCIL), Bhopal for storage of wastewater containing high concentrations of inorganic chemicals especially chlorides. Area occupied by the SEPs had to be recovered due to closure of the plant. A prerequisite to the reclamation of the SEP area is a study of adjoining soil and groundwater, which may be contaminated due to possible leakage in the pond. Surface soil, subsurface soil and groundwater samples were collected and analysed. The electrical conductivity method was employed inside the pond to test for leak in the geo-membrane liner. This was further confirmed by physically checking the liners. Based on the wet period, total rainfall and evaporation rate of the region, drying of remaining wastewater by spreading in dry ponds followed by pond dismantling was scheduled.

Chemical Industry↗
PubMed2001

Genetic contribution to bone metabolism, calcium excretion, and vitamin D and parathyroid hormone regulation.

A classical twin study was performed to assess the relative contribution of genetic and environmental factors to bone metabolism, calcium homeostasis, and the hormones regulating them. It was examined further whether the genetic effect is menopause dependent. The subjects were 2136 adult twins (98.3% female): 384 monozygotic (MZ) and 684 dizygotic (DZ) twin pairs. The intraclass correlations were calculated, and maximum likelihood model fitting was used to estimate genetic and environmental variance components. The intraclass correlations for all of the variables assessed were higher in MZ twin pairs. The heritabilities (95% CIs) obtained from model fitting for hormones regulating bone metabolism and calcium homeostasis were parathyroid hormone (PTH), 60% (54-65%); 25-hydroxyvitamin D [25(OH)D]; 43% (28-57%), 1,25-hydroxyvitamin D [1,25(OH)], 65% (53-74%); and vitamin D binding protein 62% (56-66%). The heritabilities (95% CIs) for markers of bone formation also were assessed; bone-specific alkaline phosphatase (BSAP), 74% (67-80%), and osteocalcin, 29% (14-44%); marker of bone resorption deoxypyridinoline (DPD), 58% (52-64%); and measure of calcium homeostasis 24 h urine calcium, creatinine (Cr), 52% (41-61%). The magnitude of genetic influence differed with menopause for most variables. This study provides evidence for the importance of genetic factors in determining bone resorption and formation, calcium excretion, and the hormones regulating these processes. It shows for the first time a clear genetic effect on bone resorption in premenopausal women and the regulation of PTH, vitamin D metabolism, and calcium excretion. The genes controlling bone hormones and markers are likely to be useful therapeutic and diagnostic targets.

Adolescent↗
PubMed2001

Inter-laboratory evaluation of the COBAS INTEGRA 400 analytical system.

COBAS INTEGRA 400 is a random-access analytical system consolidating assays for clinical chemistry analytes, electrolytes, serum proteins, drugs of abuse and therapeutic drugs. Analytical performance and practicability of the instrument were evaluated in seven laboratories over a 2-year period in parallel with system development. Good within-run and total imprecision for all assays was observed with a few exceptions for specimen pools with low concentration or activity. The coefficients of variation for total imprecision were well below 3.0% for clinical chemistry analytes and electrolytes, and below 5.0% for serum proteins and therapeutic drugs. Method comparisons demonstrated a good agreement with the various systems used for comparison, with slopes varying typically from 0.94 to 1.05, and Spearman correlation coefficient generally > 0.975. Accuracy was verified by recovery of controls and certified reference materials within 90 to 110% of target values. Assay ranges were linear within +/- 5%. No carry-over on reagent or sample pipetting systems was observed. Manufacturer-specified interference limits and onboard stabilities of reagents were confirmed. A time study for calculating direct personnel times and total processing time was carried out in three laboratories under different conditions including consolidated, STAT and dedicated use. On a scenario-independent basis, the total working time was shorter on the COBAS INTEGRA 400 than on routine systems in all three laboratories. Personnel time, in particular, was significantly reduced when compared to routine instruments. In general, system practicability was judged very positively in all laboratories. Owing to its versatility, the instrument is best placed as a consolidated workstation in small- to medium-sized laboratories or as an instrument for special determinations such as serum proteins, drugs, urinalysis or emergency analyses in large laboratories.

Blood Proteins↗
PubMed2001

Primary cell culture from fish gills and kidney using fish serum.

A novel, cost effective and time saving technique for primary cell culture from gills and kidney using fish serum has been developed. Single cell suspension of gills and kidney of Clarias gariepinus was obtained by trypsinization. Minimum essential medium supplemented with 10% fish serum in place of 10% foetal calf serum and 20% fish muscle extract, yielded confluent monolayer on 6th and 8th day in gill and kidney tissue respectively at 28 degrees C. Fish serum can be successfully used as media supplement for cultivation and maintenance of primary cell culture from fishes.

Animals↗
PubMed2000

Survival from head and neck cancer in Mumbai (Bombay), India.

BACKGROUND: Head and neck cancers, among the 10 most frequent cancers in the world, are common in regions with a high prevalence of tobacco and alcohol habits. They account for one-fourth of male and one-tenth of female cancers in India. The authors report and discuss the survival from these cancers in Mumbai (Bombay), India. METHODS: Follow-up information on 6311 head and neck cancer patients registered in the Bombay Population-Based Cancer Registry for the period 1987-1991 was obtained by a variety of methods, including matching with death certificates from the Bombay vital statistics registration system, postal/telephone enquiries, home visits, and scrutiny of medical records. The survival for each case was determined as the duration between the date of incidence and the date of death or date of loss to follow-up or the closing date of the study (December 31, 1996). Cumulative observed and relative survival were calculated by the Hakulinen method. For comparison of results with other populations, age-standardized relative survival (ASRS) was calculated by directly standardizing age specific relative survival to the specific age distributions of the estimated global incidence of major cancers in 1985. The log rank test was used in univariate analysis to identify the potentially important prognostic variables. The variables showing statistical significance in univariate analysis were introduced stepwise into a Cox regression model to identify the independent predictors of survival. RESULTS: The 5-year relative survival rates were 74.5% for the lip, 42.7% for the anterior tongue, 25.5% for the posterior tongue, 45.1% for the mouth, 29.7% for the oropharynx, 38.7% for the nasopharynx, 29.1% for the hypopharynx, and 41.2% for the larynx. Age, marital status, religion, and site and clinical extent of disease emerged as independent predictors of survival. Age specific 5-year relative survival declined with advancing age. Single patients had a 20% excess risk of death compared with married patients. Those with cancers of the lip, mouth, nasopharynx, and larynx had a better prognosis than those with cancer at other sites. Those with regional spread of disease experienced a threefold increased risk of death, and those with distant metastasis experienced a sixfold excess risk. Less than one-fourth of cancers were localized in the organ of origin at diagnosis; 5-year survival for localized cancers ranged from 52.9% to 80.2% depending on the subsite. CONCLUSIONS: There were significant variations in survival from cancer at individual sites within the head and neck region. Comparison with other populations revealed variations that seemed to be related to differences in detection and treatment. Tobacco and alcohol control measures and early detection linked with treatment are important measures to reduce mortality from head and neck cancer.

Adolescent↗