Biomedical subjects

S Pasupathy

Publications and source records attributed to S Pasupathy.

7 recordsLinked to original sources

PubMed2005

Effects of warm-up on exercise capacity, platelet activation and platelet-leucocyte aggregation in patients with claudication.

BACKGROUND: The effects of exercise and warm-up were investigated in patients with claudication. METHODS: This case-control crossover study involved two treadmill exercise tests, one preceded by a warm-up. Exercise continued until maximal leg pain (patients with claudication) or exhaustion (controls). Blood was taken before, and 5 and 60 min after exercise for flow cytometric analysis of platelet activation and platelet-leucocyte aggregation. RESULTS: Both cohorts (eight patients with claudication of median age 63 years and eight healthy controls of median age 63.5 years) demonstrated improvement in exercise capacity after warm-up (13.1 per cent, P = 0.012 and 15.6 per cent, P = 0.008 respectively). Platelet activation increased after exercise in patients with claudication (fibrinogen binding: 1.11 per cent before exercise versus 2.63 per cent after exercise, P = 0.008; P-selectin: 0.68 versus 1.11 per cent, P = 0.028). Neither agonist stimulation nor warm-up altered this trend. Platelet-leucocyte (PLA) and platelet-neutrophil (PNA) aggregation were similarly increased immediately after exercise in patients with claudication (PLA: 7.6 versus 13.0 per cent, P = 0.004; PNA: 6.8 versus 10.2 per cent, P = 0.012). These remained high 60 min after exercise only in patients with claudication, but recovered to baseline levels when preceded by warm-up. Warm-up significantly desensitized PNA after stimulation with 10 micromol/l adenosine 5'-diphosphate at all time points. CONCLUSION: Warm-up increased the exercise capacity of patients with claudication. Exercise induced a thromboinflammatory response, with PLA and PNA persistently increased after 60 min in patients with claudication, an effect diminished after warm-up.

Adenosine Diphosphate↗

PubMed2005

Ischaemic preconditioning protects against ischaemia/reperfusion injury: emerging concepts.

INTRODUCTION: Ischaemic preconditioning (IP) has emerged as a powerful method of ameliorating ischaemia/reperfusion (I/R) injury to the myocardium. This review investigates whether this phenomenon is universally applicable in modulating I/R injury to other tissues. METHODS: A Medline search was conducted to identify both animal and human studies that described IP-induced protection from I/R injury in a variety of non-cardiac organ systems. Particular emphasis was placed on elucidation of underlying physiological concepts. RESULTS AND CONCLUSIONS: IP utilises endogenous mechanisms in skeletal muscle, liver, lung, kidney, intestine and brain in animal models to convey varying degrees of protection from I/R injury. To date there are few human studies, but recent reports suggest that human liver, lung and skeletal muscle acquire similar protection after IP. Specifically, preconditioned tissues exhibit reduced energy requirements, altered energy metabolism, better electrolyte homeostasis and genetic re-organisation, giving rise to the concept of 'ischaemia tolerance'. IP also induces 'reperfusion tolerance' with less reactive oxygen species and activated neutrophils released, reduced apoptosis and better microcirculatory perfusion compared to non-preconditioned tissue. Systemic I/R injury is also diminished by preconditioning. IP is ubiquitous but more research is required to fully translate these findings to the clinical arena.

Adaptation, Physiological↗

PubMed2005

Systemic administration of naked DNA with targeting specificity to mammalian kidneys.

A major challenge for gene therapy is to be able to deliver efficiently the gene of interest to specific cell types. Here we describe a safe and simple effective naked DNA gene delivery method, via inferior vena cava (IVC) injection, to the recipient's kidneys. It was further demonstrated that gene expression was concentrated in the proximal tubular epithelial cells of the cortico-medullary region of the kidney. Confocal microscopy analyses demonstrated the presence of the exogenous DNA in the renal cell membrane 10 min postgene delivery. However, it was only by 30 min that the presence of the exogenous DNA could be detected in the cell cytoplasm and in the nuclei of the renal cells. Stable expression of the beta-galactosidase gene could be detected for up to 35 days and no toxicity or any adverse pathological effect associated with the delivery method could be observed. Importantly, this IVC gene delivery method could promote the targeting of genes to carcinoma established in the kidney of SCID mice. These results provide the first evidence to support that stable gene expression could be achieved in the renal cells of kidney and the established carcinoma in the kidneys following in vivo gene delivery with naked DNA and could therefore provide the potential to design protocols for the gene therapy of the kidney diseases.

Animals↗

PubMed2003

Acute embolic occlusion of the superior mesenteric artery: a case report and discussion of management.

INTRODUCTION: We present a case of acute embolus to the superior mesenteric artery (SMA). CLINICAL PICTURE: A 70-year-old gentleman with atrial fibrillation complained of colicky abdominal pain with clinical signs of tenderness and mild guarding. TREATMENT AND OUTCOME: Laparotomy revealed extensive bowel ischaemia but no overt infarction. The SMA was occluded by an embolus at the root of the mesentery and balloon catheter embolectomy was carried out at once. Bowel resection was deferred in order to allow clear demarcation of gangrene to avoid sacrificing unnecessary length. At second look laparotomy, 1.2 m of bowel from mid-jejunum to mid-ileum was resected, salvaging about 1 m of previously dusky small and large bowel. CONCLUSION: This case illustrates the importance of accurate history taking, the role of early intervention and the usefulness of a second look laparotomy in cases of mesenteric ischaemia to minimise the extent of bowel resection.

Aged↗

PubMed2001

A comparison between open versus laparoscopic assisted colonic pouches for rectal cancer.

The aim of this prospective study was to compare the surgical outcomes in patients undergoing laparoscopic assisted vs. open ultralow anterior resection (ULAR) with the creation of a colonic pouch-anal anastomosis. Patients undergoing ULAR with creation of a colonic pouch and who either had conventional open (CO) or laparoscopic assisted (LA) surgery in colorectal cancer were studied and compared. There were 33 patients, 22 in CO group and 11 in LA group. The groups were comparable for age, sex, tumour and anastomotic heights from anal verge, stage of disease, length of specimen removed and duration of surgery. Incisions were significantly shorter in the LA group (median, 9 cm vs. 16 cm, p = 0.01). Less parenteral analgesia was required in the LA group (2 days vs. 3 days, p = 0.05), but there were no significant differences in the time to passage of flatus, commencement of oral fluids or solid foods and length of hospital stay. There was no difference in morbidity or mortality. With regards to patients with Dukes A to C disease only, at a median of 12 months of follow-up, there was no patient with local or port site recurrence in the LA group. In the CO group, there was one local recurrence and two with distal metastases. In conclusion, laparoscopic assisted ULAR with colonic J pouch anal anastomosis is feasible, easy to perform and safe. It s advantages include significantly shorter incision and lower analgesic requirements postoperatively. Return of bowel function and length of hospital stay, however, are comparable to those of conventional open surgery.

Aged↗

PubMed1999

Models of local behavior of DNA electrophoresis peak parameters.

Many base calling algorithms implicitly or explicitly rely on predictions of local sequence parameters such as amplitude, peak time and peak width. For example, an algorithm may search for the next peak about a predicted peak time formed by adding the mean peak separation to the last position measurement. In this paper, covariance models are presented which characterize the dependence of peak parameters on those of other peaks. Based on experimental measurements, the model features an exponential decay in peak time jitter covariance with respect to base separation. Both peak amplitude and peak width are modelled as being uncorrelated with those of adjacent bases. In the model, linear expressions are given to describe the growth in peak time jitter and peak width as a function of base position while other parameters, such as amplitude variance, are modeled by constants. Together, these results form a simple model which may be used in the derivation of new sequencing algorithms or in simulations for the testing of such algorithms. We suggest that the correlation of the peak times is related to the Kuhn length of the single-stranded DNA fragments.

Algorithms↗

PubMed1999

Optimal structure for automatic processing of DNA sequences.

The faithful recovery of the base sequence in automatic DeoxyriboNucleic Acid (DNA) sequencing fundamentally depends on the underlying statistics of the DNA electrophoresis time series. Current DNA sequencing algorithms are heuristic in nature and modest in their use of statistical information. In this paper, a formal statistical model of the DNA time series is presented and then used to construct the optimal maximum-likelihood (ML) processor. The DNA-ML algorithm that is derived in this paper features Kalman prediction of peak locations, peak parameter estimation, whitened waveform comparison and multiple hypothesis processing using the M-algorithm. Properties of the algorithm are examined using both simulated and real data. Model parameters of critical importance and their impact on different types of error mechanisms, such as insertions and deletions, are pointed out. The statistical model of the DNA time-series and the structure of the DNA-ML algorithm provides a basis for future investigation and refinement of DNA sequencing techniques.

Algorithms↗