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Biomedical subjects

M Krishnamurthy

Publications and source records attributed to M Krishnamurthy.

At least 19 recordsLinked to original sources
PubMed2006

Energy pooling in multiple ionization and Coulomb explosion of clusters by nanosecond-long, megawatt laser pulses.

We report the results of experiments that establish the possibility of bringing about multiple ionization and Coulomb explosion of molecular clusters with nanosecond laser pulses at intensities as small as 10(9) W cm(-2). We demonstrate several new facets of the laser-cluster interaction in the low-intensity, long-pulse domain: (i) The choice of laser wavelength for a given cluster species is very crucial. (ii) Excited electronic states play a very important role in the ionization dynamics. (iii) When field ionization is insignificant and ponderomotive energies are very small, it is energy pooling rather than inverse bremsstrahlung that determines how clusters absorb energy from the optical field.

Journal Article↗
PubMed2004

Strong light fields coax intramolecular reactions on femtosecond time scales.

Energetic H(2) (+) ions are formed as a result of intramolecular rearrangement during fragmentation of linear alcohols (methanol, ethanol, propanol, hexanol, and dodecanol) induced by intense, pulsed optical fields. The laser intensity regime that is accessed in these experiments (peak intensity of 8 x 10(15) W cm(-2)) ensures multiple ionization of the irradiated alcohol molecules such that Coulomb explosions would be expected to dominate the overall fragmentation dynamics. Polarization dependent measurements show, counterintuitively, that rearrangement is induced by the strong optical field within a single, 100 fs long laser pulse, and that it occurs before Coulomb explosion of the field-ionized multiply charged alcohols.

Journal Article↗
PubMed2004

Spontaneous coronary artery dissection in the postpartum period: association with antiphospholipid antibody.

Spontaneous coronary artery dissection (SCAD) is an extremely uncommon cause of myocardial infarction, occurring predominantly in women during or after pregnancy. The exact aetiology is unknown. This report describes a 33 year postpartum woman with diagnosed SCAD who tested positive for anticardiolipin antibody. This is the first case of SCAD in a patient with antiphospholipid antibody. The authors hypothesised that there should be a strong association between them.

Adult↗
PubMed2003

Hyperfractionated radiotherapy and paclitaxel for locally advanced/unresectable pancreatic cancer.

PURPOSE: To determine prospectively the maximal tolerated dose and potential antitumor activity of weekly paclitaxel with concurrent hyperfractionated radiotherapy in patients with locally advanced and/or unresectable pancreatic cancer. METHODS AND MATERIALS: We embarked on Phase I-II study of hyperfractionated radiotherapy using a concomitant in-field boost to a total dose of 63.80 Gy in 6 weeks at 1.1 Gy/fraction. Paclitaxel was administered weekly on Days 1, 8, 15, 22, 29, and 36 as a 3-h infusion. Paclitaxel doses were escalated from 20 mg/m(2)/wk to 70 mg/m(2)/wk. Twenty patients were studied, 14 women and 6 men (mean age 64 years). Some patients presented with one or more symptoms. Obstructive jaundice was the main presenting symptom in 10 patients and epigastric pain in 14. All patients had unresectable histologically proven adenocarcinoma of the pancreas (15 head, 4 body, and 1 tail). Reasons for unresectability were involvement of the portal vein, and/or superior mesenteric artery (n = 14), paraaortic nodes (n = 8), and medically inoperable (n = 1). Fourteen patients underwent a biliary bypass procedure before treatment (four endoscopic stenting, five choledochojejunostomy, and five cholecystojejunostomy). The follow-up period ranged from 14 to 66 months (median 44). RESULTS: The dose-limiting toxicity was observed at 70 mg/m(2)/wk. Grade IV Radiation Therapy Oncology Group late GI toxicity was seen in 1 patient in the form of duodenal stricture and hemorrhage. Grade II gastrointestinal adverse effects occurred in 13 patients and Grade 3 in 1 patient. No neurologic morbidity was encountered. Eight patients required cytokine support for Grade 2 and 3 neutropenia. The treatment course was delivered within the planned time in 80% of the patients. Complete relief of pain occurred in 10 of 14 patients. The CA 19-9 level was either stable or decreasing in 12 of 15 patients. Of 17 assessable patients, stable disease was seen in 10, regression in 2, a partial response in 3, and a complete response in 2. CONCLUSION: The use of hyperfractionated radiotherapy to a dose of 63.80 Gy with concomitant weekly paclitaxel is tolerated. The maximal tolerated dose of paclitaxel for this study was 60 mg/m(2)/wk. The preliminary objective responses denote activity of the regimen. We recommend testing this regimen in larger scale studies.

Adenocarcinoma↗
PubMed2003

Clobazam monotherapy in drug naïve adult patients with epilepsy.

PURPOSE: Evaluation of the efficacy and side effects profile of Clobazam in a 24-week open-labelled trial involving 26 cases of drug naïve adult patients with epilepsy. METHODS: The study was an open labelled unicentre trial in which only drug naïve cases with epilepsy were included. A total of 26 cases were recruited. One case was dropped because he did not complete the desired follow up. Seizure type and frequency were recorded and follow up was done at 4, 8, 12, 18 and 24 weeks after initiation of therapy. The change in seizure severity, the dose of Clobazam required and development of side effects were recorded. RESULTS: The seizure types included GTCS (n=16), complex partial seizures (n=4), focal motor seizures with secondary generalisation (n=3) and juvenile myoclonic epilepsy (n=2). Out of 25 patients, 16 (64%) became seizure free, while five (20%) had >50% reduction in their seizure frequency. Thus, these 21 patients (84%) were considered to be well controlled. The commonest side effect seen was sedation, which was noted in 4 of the 25 patients (16%). However, in none of these four patients sedation was significant enough to warrant stoppage of therapy. Weight gain, gait ataxia, loss of short-term memory and breakthrough seizures were noted in one patient each. CONCLUSIONS: The efficacy of Clobazam coupled with the lack of significant side effects noted in our study makes it merit consideration as monotherapy in adult patients with epilepsy.

Adolescent↗
PubMed2002

Neurological mitochondrial cytopathies.

The mitochondrial cytopathies are genetically and phenotypically heterogeneous group of disorders caused by structural and functional abnormalities in mitochondria. To the best of our knowledge, there are very few studies published from India till date. Selected and confirmed fourteen cases of neurological mitochondrial cytopathies with different clinical syndromes admitted between 1997 and 2000 are being reported. There were 8 male and 6 female patients. The mean age was 24.42+/-11.18 years (range 4-40 years). Twelve patients could be categorized into well-defined syndromes, while two belonged to undefined group. In the defined syndrome categories, three patients had MELAS (mitochondrial encephalopathy, lactic acidosis and stroke like episodes), three had MERRF (myoclonic epilepsy and ragged red fibre myopathy), three cases had KSS (Kearns-Sayre Syndrome) and three were diagnosed to be suffering from mitochondrial myopathy. In the uncategorized group, one case presented with paroxysmal kinesogenic dystonia and the other manifested with generalized chorea alone. Serum lactic acid level was significantly increased in all the patients (fasting 28.96+/-4.59 mg%, post exercise 41.02+/-4.93 mg%). Muscle biopsy was done in all cases. Succinic dehydrogenase staining of muscle tissue showed subsarcolemmal accumulation of mitochondria in 12 cases. Mitochondrial DNA study could be performed in one case only and it did not reveal any mutation at nucleotides 3243 and 8344. MRI brain showed multiple infarcts in MELAS, hyperintensities in putaminal areas in chorea and bilateral cerebellar atrophy in MERRF.

Adolescent↗
PubMed2001

Asymmetric high-energy ion emission from argon clusters in intense laser fields.

Clusters of 2x10(3) to 4x10(4) Ar atoms are Coulomb exploded in intense (up to 8x10(15) W cm(-2)) laser fields. The dependence of multiply charged argon ion energies on the polarization state of light is probed. A directional asymmetry in the ion-explosion energies is observed for the highest charge states. The ion-energy distribution consists of a low-energy isotropic component, and a high-energy anisotropic one. The results are discussed in terms of an asymmetric Coulomb-explosion scenario.

Journal Article↗
PubMed1999

Cisplatin induced reversible bilateral vocal cord paralysis: an undescribed complication of cisplatin.

BACKGROUND: Bilateral vocal cord paralysis is uncommon. Most cases occur secondary to trauma, malignancy, surgery, or intubation. Also, it was reported as a side effect of Vinca alkaloids. METHODS: We report a patient with small cell lung cancer who developed bilateral vocal cord paralysis and needed to be intubated after treatment with cisplatin and etoposide. All workups excluded metastases as a cause of bilateral vocal cord paralysis. The patient required tracheostomy; she did not receive any further chemotherapy. After 11 weeks, vocal cord paralysis disappeared, tracheostomy was reversed, and the patient remained symptom free; however, 6 months later, the patient developed brain and liver metastases and died from her disease with no evidence of vocal cord paralysis. RESULTS: We report a case of reversible bilateral vocal cord paralysis that we believe to be secondary to cisplatin toxicity, which is an undescribed complication of this drug. CONCLUSION: Cisplatin can induce reversible bilateral vocal cord paralysis. The concurrent use of cisplatin and etoposide might have contributed to this complication in our patient.

Aged↗
PubMed1999

Acute myocardial infarction following gemcitabine therapy--a case report.

The authors report a case of acute myocardial infarction following gemcitabine infusion and electrocardiographic abnormalities suggestive of ischemia on rechallenge of the drug. The possible underlying mechanisms of ischemia and/or infarction and the strategies for prevention are discussed.

Antimetabolites, Antineoplastic↗
PubMed1993

Effects of ECT-dothiepin combination on learning in rats.

Electroconvulsive therapy (ECT) and antidepressant drugs are each known to impair learning and memory. No information is available on their effects on cognition when used concurrently in the treatment of depression, as is frequent in India. In the present study, therefore, the effects of electro-convulsive shocks (ECS) and dothiepin, separately and in combination, were studied in an animal model employing a complex maze operant learning paradigm. ECS were given on alternate days (3/week) for 2 weeks. Dothiepin (10 mg/kg, ip) was administered once daily for 2 weeks. Learning was assessed on days 2-10 post-treatment ECS produced greater initial impairment in learning while dothiepin produced a more sustained impairment. While impairment was maximum in the combined treatment group, the statistical significances that emerged to proscribed the combination were but weak.

Animals↗