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Biomedical subjects

S Somasundaram

Publications and source records attributed to S Somasundaram.

At least 19 recordsLinked to original sources

Cardiopulmonary bypass in surgery for complex-combined vascular malformation of the lower limb: case report.

A 16-year-old boy was referred with features of Parkes Weber syndrome (PWS) involving the right lower limb. He had presented at birth with cutaneous vascular malformations (VM) in the right thigh and at the age of 7 years developed congestive cardiac failure, which was controlled with drugs. He received alpha interferon and steroids during this period without any benefit. He defaulted follow-up and at 12 years of age presented with further enlargement of the VM in the right thigh and leg with skin and soft tissue thickening. At this stage, embolization and subsequent excision of the VM were tried, but the surgery was abandoned because of massive hemorrhage. Over the next 4 years, the boy became totally bedridden because of massive increase in the size of the limb, repeated hemorrhages, and secondary infection of the VM. Right hip disarticulation was considered the best option to improve his quality of life. To prevent uncontrollable hemorrhage during surgery, the disarticulation was done under cardiopulmonary bypass with low circulatory flow. Postoperatively, the patient required intensive care nursing for a week. He is presently ambulatory with crutches. Cardiopulmonary bypass with low flow has been used for treating posttraumatic arteriovenous malformations. However, its use in surgery for PWS has not been reported earlier.

Adolescent↗

Simultaneous infection with multiple strains of Mycobacterium tuberculosis identified by restriction fragment length polymorphism analysis.

Simultaneous infection with multiple strains of Mycobacterium tuberculosis was confirmed in two isolates of a total of 543 culture-positive tuberculosis patients from the Model DOTS area of Thiruvallur, South India, using IS6110 and direct repeat restriction fragment length polymorphism (DR-RFLP). The two isolates showing different intensities of IS6110 band patterns were further analysed by repeating RFLP on their alternate cultures and individual colonies. The results showed respectively two and three distinct IS6110 RFLP patterns, indicating mixed infection. The possibility of cross contamination at laboratory or DNA level was ruled out. Additional DR-RFLP also confirmed infection with multiple strains. This study found evidence of co-infection with two or three different strains of M. tuberculosis, showing distinct RFLP patterns.

Adult↗

Lingual thyroid--a lesson to learn.

We present a case of a middle-aged woman with a mass in the posterior third of the tongue which was diagnosed as a tongue haemangioma. The tumour was successfully excised via a midline mandibular osteotomy and tongue splitting approach. The histopathology examination, however, revealed the 5x4 cms mass to be a lingual thyroid. The salient features of this unusual presentation of a thyroid enlargement will be discussed.

Diagnosis, Differential↗

2, 4-diamino-6- hydroxy pyrimidine inhibits NSAIDs induced nitrosyl-complex EPR signals and ulcer in rat jejunum.

BACKGROUND: It has been suggested that one aspect of non-steroidal anti-inflammatory drugs induced intestinal damage is due to either uncoupling of mitochondrial oxidative phosphorylation or inhibition of electron transport. We investigated the latter possibility using electron paramagnetic resonance spectroscopy. RESULTS: Electron paramagnetic studies of NSAIDS on sub-mitochondrial particles revealed that indomethacin, but not with nabumetone, bound to a site near to Complex I and ubiquinone to generate a radical species. Normal rats exhibited prominent [3Fe-4S]ox signals (g approximately 2.01) at 20 K. One hour after indomethacin there was a prominent, intense and broad absorption pattern at (g approximately 2.07) suggesting, appearance of radical species overlapping [3Fe-4S]ox and was unaffected by pretreatment with 2,4 diamino -6-hydroxy pyrimidine. At 24 hrs, when macroscopic ulcers were seen, there was a new signal due to a nitric oxide radical (NO*). In contrast, nabumetone and 2,4 diamino-6-hydroxy pyrimidine pre-treated animals receiving indomethacin exhibited electron paramagnetic resonance spectra identical to those of controls at 24 hrs and neither was associated with small intestinal ulcers. Indomethacin and 2,4 diamino hydroxy pyrimidine pre-treated rats, but not nabumetone, had increased intestinal permeability. CONCLUSION: The results suggest that the in vivo effects of indomethacin modulate the mitochondrial respiratory chain directly at 1 h and 24 h through formation of nitric oxide. NO* appears to play an important role in the late pathogenic stages of NSAID enteropathy and may be the site for targeted treatment to reduce their toxicity.

Animals↗

A review of burns patients admitted to the Burns Unit of Hospital Universiti Kebangsaan Malaysia.

This is a retrospective review of 110 patients admitted to the Burns Units between October 1999 and November 2001. The aim was to determine the burns pattern of patients admitted to hospital UKM. There was an increasing trend for patients admitted. Female to male ratio was 1:2. Children consisted 34% of the total admission. Children had significant higher number of scald burns as compare to adult (p < 0.01). Domestic burns were consist of 75% overall admission. Mean percentage of TBSA (total body surface area) burns was 19%. Thirty percent of patients sustained more than 20% of TBSA. Sixty percent of patients had scald burns. Ninety percents of patients with second degree burns that were treated with biologic membrane dressing or split skin graft. Mean duration of hospital stay was 10 days. Over 70% of patients were discharged within 15 days. Overall mortality rate was 6.3%. The patients who died had significantly larger area of burns of more than 20% TBSA (p < 0.05) and a higher incidence of inhalation injury (p < 0.02). Hence, this study suggests a need for better preventive measures by the authority to prevent burns related accident and the expansion of the service provided by the Burns Unit.

Adult↗

Ileal mucosal bile acid absorption is increased in Cftr knockout mice.

BACKGROUND: Excessive loss of bile acids in stool has been reported in patients with cystic fibrosis. Some data suggest that a defect in mucosal bile acid transport may be the mechanism of bile acid malabsorption in these individuals. However, the molecular basis of this defect is unknown. This study examines the expression of the ileal bile acid transporter protein (IBAT) and rates of diffusional (sodium independent) and active (sodium dependent) uptake of the radiolabeled bile acid taurocholate in mice with targeted disruption of the cftr gene. METHODS: Wild-type, heterozygous cftr (+/-) and homozygous cftr (-/-) mice were studied. Five one-cm segments of terminal ileum were excised, everted and mounted onto thin stainless steel rods and incubated in buffer containing tracer 3H-taurocholate. Simultaneously, adjacent segments of terminal ileum were taken and processed for immunohistochemistry and Western blots using an antibody against the IBAT protein. RESULTS: In all ileal segments, taurocholate uptake rates were fourfold higher in cftr (-/-) and two-fold higher in cftr (+/-) mice compared to wild-type mice. Passive uptake was not significantly higher in cftr (-/-) mice than in controls. IBAT protein was comparably increased. Immuno-staining revealed that the greatest increases occurred in the crypts of cftr (-/-) animals. CONCLUSIONS: In the ileum, IBAT protein densities and taurocholate uptake rates are elevated in cftr (-/-) mice > cftr (+/-) > wild-type mice. These findings indicate that bile acid malabsorption in cystic fibrosis is not caused by a decrease in IBAT activity at the brush border. Alternative mechanisms are proposed, such as impaired bile acid uptake caused by the thick mucus barrier in the distal small bowel, coupled with a direct negative regulatory role for cftr in IBAT function.

Animals↗

Systemic effects of acute terminal ileitis on uninflamed gut aggravate bile acid malabsorption.

BACKGROUND: Some patients with terminal ileitis suffer from significant bile acid malabsorption even if the inflammation is locally limited. We hypothesized that inflammation in the terminal ileum may lead to changes in mucosal absorption in more proximal intestinal segments and aggravate bile acid malabsorption. METHODS: Five hamsters underwent laparotomy and localized instillation of 2,4,6-trinitrobenzenesulfonic acid (TNBS) in 10% ethanol into the last 4 cm of ileum to create terminal ileitis. A control group (n = 5) underwent instillation of saline. Animals were sacrificed after 24 h. Active and passive transport of radiolabeled bile acids was measured in the proximal and terminal ileum and glucose absorption in the jejunum using an everted sleeve technique. Myeloperoxidase (MPO) activity and histomorphology were examined by standard methods. RESULTS: In animals with ileitis, active bile acid uptake decreased by 84% in the terminal ileum (t test, P <0.001) and by 58% in the proximal ileum (P < 0.05) compared with saline-treated controls. Jejunal glucose absorption decreased by 59% (P < 0.01). Passive bile acid and glucose absorption rates were not significantly changed in any segments of treated animals versus controls. Histological examination of the treated group revealed signs of acute terminal ileitis without changes in the proximal ileum and jejunum. All control tissues were uninflamed. MPO activity was 13-fold increased in the inflamed ileal samples compared with controls (P <0.001). No significant changes were seen in the proximal ileum and jejunum. There was no evidence of reflux of TNBS into proximal ileum. Nominal mucosal surface area values showed no significant changes between groups. Pretreatment of an additional group of hamsters (n = 5) with acetylsalicylic acid before TNBS instillation ameliorated the inflammatory response in the terminal ileum and largely abrogated the negative effects on ileal bile acid absorption. CONCLUSION: These data suggest that limited acute ileitis impairs active bile acid uptake in the terminal ileum. It also diminishes active bile acid and glucose absorption in more proximal segments of the small intestine, likely by a systemic effect. This systemic effect may aggravate bile acid malabsorption in patients with limited ileitis.

Acute Disease↗

A simple method for measuring of intestinal solute transport in mucosal biopsy specimens.

Accurate in vitro measurements of intestinal mucosal solute uptake in humans are often difficult because only small amounts of tissue material are available. We describe a miniaturized everted sleeve method of measuring intestinal solute uptake in endoscopy biopsy samples that combines simplicity, good tissue viability and reproducibility. Biopsies were mounted on a dressmaker needle head stationed immediately over a stirring bar rotating at 1200 rpm. This approach was used to measure taurocholate uptake in sheep and human endoscopy biopsies. Comparison was made to conventional standardized everted sleeve preparations. Na+-dependent uptake rates correlated well among individual sheep (R2 = 0.88, P < 0.05). There was excellent correlation between conventional and biopsy preparations in humans (R2 = 0.98; P < 0.05). The biopsy method overestimated diffusional uptake rates in sheep and humans by two to three fold when compared to conventional everted sleeve preparations. We conclude that this method is valuable to measure Na+-dependent solute uptake rates in biopsy samples from human intestine.

Animals↗

Distribution of bile acid absorption and bile acid transporter gene message in the hamster ileum.

The apical, Na-dependent, ileal bile acid transporter (IBAT) is critical for the reabsorption of bile acids in the ileum. Bile acid transport capacities as well as the distribution of bile acid transporter messenger ribonucleic acid (mRNA) and transporter protein were studied along the axis of the ileum. Na-dependent and Na-independent taurocholate uptake was measured in the hamster ileum using an everted-sleeve technique. The distribution of IBAT mRNA and protein were mapped by in-situ hybridization, immunohistochemistry, and Western blotting. Na-dependent and Na-independent bile acid uptake rates were highest 1-4 cm before the ileocecal valve (maxima 780 and 120 pmol/mm2 per min, respectively) and decreased proximally and distally. Na-independent absorption was increased in the last 6 cm of the ileum. IBAT mRNA and protein expression were linked closely to the distribution of uptake capacity. IBAT mRNA was more abundant near the crypt-villus junction whereas the protein was expressed evenly along the villus axis. We conclude that Na-dependent and Na-independent bile acid absorption capacities both have distinct distribution curves in the hamster ileum. All ileocytes on villi in the high-uptake area of the ileum express IBAT mRNA and protein.

Animals↗

Uncoupling of intestinal mitochondrial oxidative phosphorylation and inhibition of cyclooxygenase are required for the development of NSAID-enteropathy in the rat.

BACKGROUND: The pathogenesis of NSAID-induced gastrointestinal damage is believed to involve a nonprostaglandin dependent effect as well as prostaglandin dependent effects. One suggestion is that the nonprostaglandin mechanism involves uncoupling of mitochondrial oxidative phosphorylation. AIMS: To assess the role of uncoupling of mitochondrial oxidative phosphorylation in the pathogenesis of small intestinal damage in the rat. METHODS: We compared key pathophysiologic events in the small bowel following (i) dinitrophenol, an uncoupling agent (ii) parenteral aspirin, to inhibit cyclooxygenase without causing a 'topical' effect and (iii) the two together, using (iv) indomethacin as a positive control. RESULTS: Dinitrophenol altered intestinal mitochondrial morphology, increased intestinal permeability and caused inflammation without affecting gastric permeability or intestinal prostanoid levels. Parenteral aspirin decreased mucosal prostanoids without affecting intestinal mitochondria in vivo, gastric or intestinal permeability. Aspirin caused no inflammation or ulcers. When dinitrophenol and aspirin were given together the changes in intestinal mitochondrial morphology, permeability, inflammation and prostanoid levels and the macro- and microscopic appearances of intestinal ulcers were similar to indomethacin. CONCLUSIONS: These studies allow dissociation of the contribution and consequences of uncoupling of mitochondrial oxidative phosphorylation and cyclooxygenase inhibition in the pathophysiology of NSAID enteropathy. While uncoupling of enterocyte mitochondrial oxidative phosphorylation leads to increased intestinal permeability and low grade inflammation, concurrent decreases in mucosal prostanoids appear to be important in the development of ulcers.

Animals↗

Induction of porcine cytokine mRNA expression after DNA immunization and pseudorabies virus infection.

Injection of plasmid DNA encoding pseudorabies virus (PRV) glycoprotein into pig muscle has been shown to result in protective immunity against lethal infection. Here, pigs were vaccinated by a single coinjection of three plasmids encoding PRV glycoproteins gB, gC, and gD, with plasmid expressing porcine granulocytemacrophage colony-stimulating factor (GM-CSF) or porcine interferon-alpha (IFN-alpha). DNA immunization induced a primary T cell-mediated response characterized by low rates of IFN-gamma, interleukin-2 (IL-2), and IL4 mRNA in peripheral blood mononuclear cells (PBMC). Very low rates of PRV-specific IgG1 and the absence of IgG2 were obtained. Codelivery of plasmid expressing GM-CSF or IFN-alpha had no effect on cytokine mRNA expression or on B cell response. After a high virulent challenge, high levels of cytokine mRNA, mainly IFN-gamma, and high secondary antibody (Ab) response were induced in all DNA-vaccinated pigs. Codelivery of GMCSF gene significantly increased both Th immune response (i.e., IFN-gamma and IL-4 mRNA expression) and clinical protection but had no effect on secondary B immune response. Codelivery of IFN-alpha gene had no beneficial effect on secondary T and B cell immune responses.

Animals↗

Comparison of indomethacin and nimesulide, a selective cyclooxygenase-2 inhibitor, on key pathophysiologic steps in the pathogenesis of nonsteroidal anti-inflammatory drug enteropathy in the rat.

BACKGROUND: The predicted gastrointestinal tolerability of specific cyclooxygenase-2 inhibitors could be due to either a lack of 'topical' irritation and/or lack of effect on cyclooxygenase-1. METHODS: Key pathophysiologic steps (in vitro and in vivo uncoupling, intestinal prostanoid levels (prostaglandin E, thromboxane B2, and 6-keto-prostaglandin F1alpha), intestinal permeability (51Cr-ethylenediaminetetraacetic acid), inflammation (faecal excretion of a granulocyte marker protein), and ulcer counts) in enteropathy induced by nonsteroidal anti-inflammatory drugs were assessed after administration of indomethacin, 10 mg/kg, and 15 (roughly equipotent), 30, and 60 mg/kg of the preferential cyclooxygenase-2 inhibitor nimesulide. RESULTS: Indomethacin uncoupled oxidative phosphorylation at lower concentrations than nimesulide in vitro. Indomethacin was associated with electron microscopy changes suggestive of uncoupling in 60%-70% of enterocytes examined, whereas nimesulide affected 10%-30% of enterocytes, depending on the dose. Indomethacin increased intestinal permeability and caused inflammation and ulcers with 71%-96% reductions in prostanoid levels. Nimesulide at 15 mg/kg caused no damage, whereas 30 and 60 mg/kg nimesulide were associated with significant decreases in mucosal prostanoids (46%-75%), but only the 60-mg/kg dose caused a transient increase in intestinal permeability. However, at none of the doses did nimesulide cause intestinal inflammation or ulcers. CONCLUSIONS: These results endorse the idea that selective cyclooxygenase-2 inhibitors may be associated with some gastrointestinal tolerance due to their selectivity for cyclooxygenase-2, inhibiting cyclooxygenase-1 at only very high doses, and reduced topical irritation.

Animals↗

Enantiomers of flurbiprofen can distinguish key pathophysiological steps of NSAID enteropathy in the rat.

BACKGROUND: Non-steroidal anti-inflammatory drugs (NSAIDs) cause gastrointestinal damage by a non-prostaglandin (PG) dependent "topical" action and by inhibiting cyclooxygenase. AIMS: To discriminate between these two effects by studying some key pathophysiological steps in NSAID enteropathy following administration of (R)- and (S)-flurbiprofen, the racemic mixture, and an uncoupler, dinitrophenol. METHODS: The effects of dinitrophenol, racemic, (R)-, and (S)-flurbiprofen on mitochondria were assessed in vitro and on key pathophysiological features of small intestinal damage in vivo (ultrastructure by electron microscopy, mucosal prostanoid concentrations, intestinal permeability, inflammation, and ulcer count) in rats. RESULTS: All the drugs uncoupled mitochondrial oxidative phosphorylation in vitro, caused mitochondrial damage in vivo, and increased intestinal permeability. Dinitrophenol and (R)-flurbiprofen caused no significant decreases in mucosal prostanoid concentrations (apart from a decrease in thromboxane (TX) B2 concentrations following (R)-flurbiprofen) while racemic and (S)- flurbiprofen reduced mucosal prostanoids significantly (PGE, TXB2, and 6-keto-PGF1alpha concentrations by 73-95%). Intestinal inflammation was significantly greater following administration of (S)-flurbiprofen and racemate than with dinitrophenol and (R)-flurbiprofen. No small intestinal ulcers were found following dinitrophenol or (R)-flurbiprofen while both racemic and (S)-flurbiprofen caused numerous ulcers. CONCLUSIONS: Dinitrophenol and (R)-flurbiprofen show similarities in their actions to uncouple mitochondrial oxidative phosphorylation in vitro, alter mitochondrial morphology in vivo, increase intestinal permeability, and cause mild inflammation without ulcers. Concurrent severe decreases in mucosal prostanoids seem to be the driving force for the development of severe inflammation and ulcers.

Animals↗

Intestinal tolerability of nitroxybutyl-flurbiprofen in rats.

BACKGROUND: Nitric oxide derivatives of non-steroidal anti-inflammatory drugs (NSAIDs) are thought to be much less ulcerogenic than their parent compounds. AIM: To compare the effect and potency of flurbiprofen and nitroxybutyl-flurbiprofen to uncouple mitochondrial oxidative phosphorylation (an early pathogenic event in NSAID enteropathy), increase intestinal permeability (transitional stage), and cause macroscopic small intestinal damage. METHODS: In vitro uncoupling potency was assessed using isolated coupled rat liver mitochondria and in vivo by electron microscopy of rat small intestinal mucosa (two hours after the drugs). A dose-response study with flurbiprofen (single doses of 5, 10, 20, and 40 mg/kg) and equimolar doses of nitroxybutyl-flurbiprofen was performed; assessing their effect on intestinal permeability (at 18-20 hours), with 51Cr EDTA, and the number of pointed (< 5 mm) and longitudinal (> 5 mm) small intestinal ulcers at 24 hours. RESULTS: Flurbiprofen, but not nitroxybutyl-flurbiprofen, stimulated coupled respiration in vitro. Both drugs, however, uncoupled in vivo; in the case of nitroxybutyl-flurbiprofen possibly because hydrolysis of its ester bond released free flurbiprofen. Intestinal permeability was uniformly and equally increased with both drugs compared with controls. The number of small intestinal ulcers, pointed and longitudinal, was significantly reduced with nitroxybutyl-flurbiprofen apart from the number of longitudinal ulcers with the highest dose. CONCLUSIONS: These studies show that nitroxybutyl-flurbiprofen is associated with significantly less macroscopic damage in the small intestine than flurbiprofen but was associated with mitochondrial damage in vivo and caused similar increases in permeability of the small intestine, suggesting that its beneficial effect is on the later pathogenic stages of the damage.

Animals↗

Mitochondrial damage: a possible mechanism of the "topical" phase of NSAID induced injury to the rat intestine.

BACKGROUND: The "topical" effect of non-steroidal anti-inflammatory drugs (NSAIDs) seems to be an important cause of NSAID induced gastrointestinal damage. AIM: To examine the possible mechanism of the "topical" phase of damage in the small intestine. METHODS: Electron microscopy and subcellular organelle marker enzyme studies were done in rat small intestine after oral administration of indomethacin (doses varied between 5 and 30 mg/kg). The effect of conventional and non-acidic NSAIDs on rat liver mitochondrial respiration was measured in vitro in a Clarke-type oxygen electrode. RESULTS: The subcellular organelle marker enzymes showed mitochondrial and brush border involvement within an hour of indomethacin administration. Electron microscopy showed dose dependent mitochondrial changes following indomethacin administration consistent with uncoupling of oxidative phosphorylation (or inhibition of electron transport) which were indistinguishable from those seen with the uncoupler dinitrophenol. Parenteral indomethacin caused similar changes, but not in rats with ligated bile ducts. A range of NSAIDs, but not paracetamol or non-acidic NSAIDs which have a favourable gastrointestinal tolerability profile, uncoupled oxidative phosphorylation in vitro at micromolar concentrations and inhibited respiration at higher concentrations. In vivo studies with nabumetone and aspirin further suggested that uncoupling or inhibition of electron transport underlies the "topical" phase of NSAID induced damage. CONCLUSION: Collectively, these studies suggest that NSAID induced changes in mitochondrial energy production may be an important component of the "topical" phase of damage induction.

Acetaminophen↗

Assessing the site of increased intestinal permeability in coeliac and inflammatory bowel disease.

BACKGROUND: The precise site of intestinal permeability changes in patients with coeliac and inflammatory bowel disease is unknown. AIMS: To design a non-invasive technique for the localisation of altered gastrointestinal permeability to 51chromium labelled EDTA (51CrEDTA). The method depends on comparing and defining concentration/time profiles in serum of a series of simultaneously ingested indicators with a well defined absorption site (3-0-methyl-D-glucose (jejunal indicator), 57cobalt labelled vitamin B12 (ileal indicator), and sulphasalazine (caecal-colonic indicator)) in relation to simultaneously ingested 51CrEDTA. SUBJECTS: Five normal controls, six patients with untreated coeliac disease, five with Crohn's ileitis, and five with pan-ulcerative colitis underwent study, which entailed the simultaneous ingestion of the above four test substances followed, during the next 24 hours, by timed serial collection of urine and serum for marker analysis. RESULTS: Urinary excretion of 51CrEDTA was significantly increased in all patient groups. Analysis of serum appearances and profiles of the markers suggested that the increased intestinal permeation of 51CrEDTA took place in the diseased jejunum in patients with coeliac disease, predominantly in the ileum in Crohn's disease and in the colon in the patients with pan-ulcerative colitis. CONCLUSION: A new non-invasive technique has been assessed that permits the localisation of the site of permeability changes with the gastrointestinal tract.

Adult↗