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Biomedical subjects

Arun K Gupta

Publications and source records attributed to Arun K Gupta.

At least 19 recordsLinked to original sources
PubMed2007

Hyperventilation following head injury: effect on ischemic burden and cerebral oxidative metabolism.

OBJECTIVE: To determine whether hyperventilation exacerbates cerebral ischemia and compromises oxygen metabolism (CMRO2) following closed head injury. DESIGN: A prospective interventional study. SETTING: A specialist neurocritical care unit. PATIENTS: Ten healthy volunteers and 30 patients within 10 days of closed head injury. INTERVENTIONS: Subjects underwent oxygen-15 positron emission tomography imaging of cerebral blood flow, cerebral blood volume, CMRO2, and oxygen extraction fraction. In patients, positron emission tomography studies, somatosensory evoked potentials, and jugular venous saturation (SjO2) measurements were obtained at Paco2 levels of 36+/-3 and 29+/-2 torr. MEASUREMENTS AND MAIN RESULTS: We estimated the volume of ischemic brain and examined the efficiency of coupling between oxygen delivery and utilization using the sd of the oxygen extraction fraction distribution. We correlated CMRO2 to cerebral electrophysiology and examined the effects of hyperventilation on the amplitude of the cortical somatosensory evoked potential response. Patients showed higher ischemic brain volume than controls (17+/-22 vs. 2+/-3 mL; p<or=.05), with worse matching of oxygen delivery to demand (p<.001). Hyperventilation consistently reduced cerebral blood flow (p<.001) and resulted in increases in oxygen extraction fraction and ischemic brain volume (17+/-22 vs. 88+/-66 mL; p<.0001), which were undetected by SjO2 monitoring. Mean CMRO2 was slightly increased following hyperventilation, but responses were extremely variable, with 28% of patients demonstrating a decrease in CMRO2 that exceeded 95% prediction intervals for zero change in one or more regions. CMRO2 correlated with cerebral electrophysiology, and cortical somatosensory evoked potential amplitudes were significantly increased by hyperventilation. CONCLUSIONS: The acute cerebral blood flow reduction and increase in CMRO2 secondary to hyperventilation represent physiologic challenges to the traumatized brain. These challenges exhaust physiologic reserves in a proportion of brain regions in many subjects and compromise oxidative metabolism. Such ischemia is underestimated by common bedside monitoring tools and may represent a significant mechanism of avoidable neuronal injury following head trauma.

Adolescent↗
PubMed2006

Endovascular treatment of direct carotid cavernous fistulae: a pictorial review.

INTRODUCTION: Direct carotid-cavernous fistulae (CCFs) are type A fistulae according to Barrow's classification. Endovascular treatment of these lesions is challenging. METHODS: The purpose of this review was to evaluate the endovascular treatment of direct CCFs. We also describe the technique, symptomatology and complications associated with the procedure and report on the long-term follow-up in our treated patients. RESULTS: A total of 89 patients with a direct CCF were treated. All patients had baseline brain CT or MR imaging. Treatment comprised transarterial balloon or coil embolizations. The patients were followed up at 1 month and then every 6 months thereafter. Detachable balloons were used in 79 fistulae. In 12 fistulae the balloon could not be negotiated through the fistula and these fistulae were treated with transarterial coil occlusion. Clinical outcomes of the treated patients evaluated at 1 month were: 79 patients (88.8%) cured, 9 (10.1%) significantly improved, 1 (1.1%) remaining static. CONCLUSION: Endovascular treatment of direct CCFs is safe and effective and results in long-term cure.

Adolescent↗
PubMed2006

Wavelet-modified maximum average correlation height filter for rotation invariance that uses chirp encoding in a hybrid digital-optical correlator.

We discuss and implement a wavelet-modified maximum average correlation height (MACH) filter for 0 degrees -360 degrees in-plane rotations in a hybrid digital-optical correlator. Use of a wavelet transform improves the performance of the MACH filter by reducing the number of filters that are required to identify a target rotated at any angle between 0 degrees and 360 degrees in-plane rotations and enhances the autocorrelation peak intensity significantly. The output of a hybrid digital-optical correlator contains two autocorrelation peaks and a strong dc. Using a chirp function with the wavelet-modified MACH filter, the correlation signals are focused in three different planes. Thus placing a peak-capturing CCD camera at a particular plane, only one autocorrelation peak is recorded, discarding the strong dc and other autocorrelation peaks. A signal-to-noise ratio has been calculated as a metric of goodness of the proposed wavelet-modified MACH filter.

Journal Article↗
PubMed2006

Percutaneous laser disc decompression: clinical experience at SCTIMST and long term follow up.

BACKGROUND: Low backache (LBA) is now increasing in younger population due to misdirected spinal kinetics secondary to improper posture, heavy load lifting and motorbike driving. Hence minimally invasive procedures are increasingly sought after. Among these, PLDD is currently popular and in use. We present our long term follow-up in the use of Nd:YAG laser for PLDD. AIM: To evaluate the efficacy of PLDD in treatment of contained herniation of lumbar discs & long term follow up results. MATERIALS AND METHODS: Forty patients with contained lumbar disc herniation on MRI and who did not respond to 6 weeks conservative treatment were subjected to PLDD. L4-5 disc was treated in 31, L5-S1 in 12 and L1-2 and L3-4 in one each. Nd:YAG laser at 1064 nm was used for the procedure. Total laser energy of 1500-2000 Joules was delivered at the disc space depending upon the size. RESULTS: There was immediate pain relief in 32/40 (80%). According to MacNab criteria good to fair response was seen in 37/40 (92%) and 3 patients (7.5%) responded poorly to this treatment. On follow up which ranged from 1 to 7 years, 34/40 (85%) had pain relief with no need for further treatment. COMPLICATIONS: Significant pain at local puncture site was experienced by 8 (20%), pain during lasing was experienced by one. One patient developed muscular spasm. CONCLUSION: Percutaneous laser disc decompression is a safe, relatively noninvasive and effective treatment modality for contained, nonsequestered, herniated lumbar disc disease in carefully selected patients.

Adult↗
PubMed2006

Development of pharmacophoric model of condensed pyridine and pyrimidine analogs as hydroxymethyl glutaryl coenzyme A reductase inhibitors.

Quantitative structure-activity relationship (QSAR) has been established on a series of thirty-eight compounds of four different sets of condensed pyridine and pyrimidine analogs, for their hydroxymethyl glutaryl coenzyme (HMG-CoA) reductase inhibitor activity, in order to understand the essential structural requirement for binding with receptor, in terms of common biophoric and secondary sites employing APEX-3D software. Among several 3D pharmacophoric models with different sizes and arrangements, one model was selected based on r2 = 0.8, chance<0.001, match equivalent to 0.38 and all the 38 compounds were considered. The results suggest that hydrophobicity, hydrogen acceptor and optimum steric refractivity play a dominant role in the inhibition of HMG-CoA reductase. The information obtained from the present study can be used to design and predict more potent molecules as HMG-CoA reductase inhibitors, prior to their synthesis.

Drug Design↗
PubMed2005

Quantitative structure-activity analysis of 5-arylidene-2,4-thiazolidinediones as aldose reductase inhibitors.

Design of aldose reductase (ALR2) inhibitors has received considerable attention. Aldose reductase inhibitors, when administered from the onset of hyperglycemia, prevent the progression of polyol accumulation-linked complications. The feasibility that inhibition of aldose reductase provides a pharmacologically direct treatment for diabetic complications that is independent of the control of blood sugar levels has spurred the development of structurally diverse aldose reductase inhibitors. In this work, we report quantitative structure-activity relationship (QSAR) analysis performed by 3D-QSAR analysis, Hansch analysis, and Fujita-Ban analysis on a series of 5-arylidene-2,4-thiazolidinediones as aldose reductase inhibitors. The 2D & 3D-QSAR models were generated using 18 compounds and Fujita-Ban analysis models were obtained using 23 compounds. The predictive ability of the resulting 2D and 3D models was evaluated against a test set of 5 compounds. Analyses of results from the present QSAR study inferred that 3rd position of the phenyl ring and acetic acid substitution at N-position of thiazolidinediones play a key role in the aldose reductase inhibitory activity.

Aldehyde Reductase↗
PubMed2005

Midterm results with hepatectomy after preoperative chemotherapy in hepatoblastoma.

We evaluated the results of surgical treatment for hepatoblastoma in infants and children after intensive preoperative chemotherapy, with special reference to histology and extent of liver involvement. The clinical features of 10 children with hepatoblastoma were reviewed regarding response to neoadjuvant chemotherapy, histological subtypes, extent of hepatectomy, operative complications, and prognosis. Response to chemotherapy was measured by volumetric assessment of tumour size by computed tomography scan. Cisplatin and Adriamycin (PLADO regime) up to three cycles markedly reduced the tumour volume on computed tomography (mean regression rate 65.9%); alpha-foetoprotein (AFP) levels also decreased from an initial mean of 16,116.4 ng/ml to 2,050.9 ng/ml. Five patients underwent right hepatectomy, two had right trisegmentectomy, two had left hepatectomy, and one had left trisegmentectomy. Histopathology of resected specimens revealed foetal histology in four patients, poorly differentiated (anaplastic) subtype in three, and mixed histology with mesenchymal components and osteoid formation in three. There was 100% resectability including six unresectable tumours (prechemotherapy). Moreover, hepatic resection tended to be less invasive in patients whose tumours had been much reduced after preoperative chemotherapy. Preoperative administration of cisplatin and Adriamycin reduces the tumour size significantly so that a safe radical hepatectomy can be performed. It also allows early administration of postoperative chemotherapy. Although overall good results were obtained with the current protocol, we also document our experience of unfavourable outcomes in patients with bilobar tumours (despite trisegmentectomy), patients with tumours showing poor response to neoadjuvant chemotherapy, and patients with anaplastic histology. Overall, at a 60-month follow-up we report an 80% survival rate by a combined approach.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2005

Invasive colonic mucormycosis in early induction therapy of childhood acute lymphoblastic leukemia.

Fungal infections occur in patients who are severely immunocompromised with profound and prolonged neutropenia. We report a patient of acute lymphoblastic leukemia who developed nonspecific abdominal symptoms within two days after the onset of neutropenia in the early induction phase of chemotherapy, which was later found to be due to intestinal mucormycosis and resulted in a fatal outcome.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2005

Early sternal erosion and luetic aneurysms of thoracic aorta: report of 6 cases and analysis of cause-effect relationship.

Six patients with luetic aneurysm of the ascending aorta eroding the sternum are presented. The erosion was an early and principal presentation and the site of erosion and location and morphology of aneurysm were identical in all six patients. The erosion mainly affected the right half of the manubrium and medial end of right clavicle. The aneurysms arose from the junction of the ascending and transverse arches of the thoracic aorta and had narrow opening close to the origin of the innominate artery. The identical presentation, aetiology, angiographic location and morphology, corroborated further at surgery, suggests that syphilitic aneurysms in this location have a strong tendency to cause early sternal erosion.

Adult↗
PubMed2005

Hyperperfusion syndrome after supraaortic vessel interventions and bypass surgery.

Cerebral hyperperfusion and hemorrhage is a recognized complication of endarterectomy, aortocarotid bypass surgery or angioplasty and stenting of the carotid or vertebral artery. We performed 87 balloon angioplasty, stenting and bypass surgery of arteries supplying the brain over the last 15 years. We have found 6 cases of hyperperfusion syndrome in a total of 87 procedures. So the incidence of hyperperfusion was noted as 6.89%. Two cases occurred after two combined procedures in a single sitting. Hyperperfusion syndrome is a well-known complication of craniocervical revascularisation procedures. But with proper care, including strict post procedural control of blood pressure and staged procedure in case of multiples vessel stenosis, these complications can be largely avoided.

Adult↗
PubMed2005

Effect of cerebral perfusion pressure augmentation on regional oxygenation and metabolism after head injury.

OBJECTIVE: In this study we have used O positron emission tomography, brain tissue oxygen monitoring, and cerebral microdialysis to assess the effects of cerebral perfusion pressure augmentation on regional physiology and metabolism in the setting of traumatic brain injury. DESIGN: Prospective interventional study. SETTING: Neurosciences critical care unit of a university hospital. PATIENTS: Eleven acutely head-injured patients requiring norepinephrine to maintain cerebral perfusion pressure. INTERVENTIONS: Using positron emission tomography, we have quantified the response to an increase in cerebral perfusion pressure in a region of interest around a brain tissue oxygen sensor (Neurotrend) and microdialysis catheter. Oxygen extraction fraction and cerebral blood flow were measured with positron emission tomography at a cerebral perfusion pressure of approximately 70 mm Hg and approximately 90 mm Hg using norepinephrine to control cerebral perfusion pressure. All other aspects of physiology were kept stable. MEASUREMENTS AND MAIN RESULTS: Cerebral perfusion pressure augmentation resulted in a significant increase in brain tissue oxygen (17 +/- 8 vs. 22 +/- 8 mm Hg; 2.2 +/- 1.0 vs. 2.9 +/- 1.0 kPa, p < .001) and cerebral blood flow (27.5 +/- 5.1 vs. 29.7 +/- 6.0 mL/100 mL/min, p < .05) and a significant decrease in oxygen extraction fraction (33.4 +/- 5.9 vs. 30.3 +/- 4.6 %, p < .05). There were no significant changes in any of the microdialysis variables (glucose, lactate, pyruvate, lactate/pyruvate ratio, glycerol). There was a significant linear relationship between brain tissue oxygen and oxygen extraction fraction (r = .21, p < .05); the brain tissue oxygen value associated with an oxygen extraction fraction of 40% (the mean value for oxygen extraction fraction in normal controls) was 14 mm Hg (1.8 kPa). The cerebral perfusion pressure intervention resulted in a greater percentage increase in brain tissue oxygen than the percentage decrease in oxygen extraction fraction; this suggests that the oxygen gradients between the vascular and tissue compartments were reduced by the cerebral perfusion pressure intervention. CONCLUSIONS: Cerebral perfusion pressure augmentation significantly increased levels of brain tissue oxygen and significantly reduced regional oxygen extraction fraction. However, these changes did not translate into predictable changes in regional chemistry. Our results suggest that the ischemic level of brain tissue oxygen may lie at a level below 14 mm Hg (1.8 kPa); however, the data do not allow us to be more specific.

Adolescent↗
PubMed2004

Effect of cerebral perfusion pressure augmentation with dopamine and norepinephrine on global and focal brain oxygenation after traumatic brain injury.

OBJECTIVE: To compare the effects of a cerebral perfusion pressure (CPP) intervention achieved with dopamine and norepinephrine after severe head injury. DESIGN: Prospective, controlled, trial. SETTING: Neurosciences critical care unit. PATIENTS: Eleven patients with a head injury, requiring dopamine or norepinephrine infusions to support CPP. INTERVENTION: Cerebral tissue gas measurements were recorded using a multimodal sensor, and regional chemistry was assessed using microdialysis. Patients received in, randomised order, either dopamine or norepinephrine to achieve and maintain a CPP of 65 mmHg, and then, following a 30-min period of stable haemodynamics, a CPP of 85 mmHg. Data were then acquired using the second agent. Haemodynamic measurements and measurements of cerebral physiology were made during each period. MEASUREMENTS AND RESULTS: The CPP augmentation with norepinephrine, but not with dopamine, resulted in a significant reduction in arterial-venous oxygen difference (37+/-11 vs 33+/-12 ml/l) and a significant increase in brain tissue oxygen (2.6+/-1.1 vs 3.0+/-1.1 kPa). The CPP intervention did not significantly affect intracranial pressure. There were no significant differences between norepinephrine and dopamine on cerebral oxygenation or metabolism either at baseline or following a CPP intervention; however, the response to a CPP intervention with dopamine seemed to be more variable than the response achieved with norepinephrine. CONCLUSIONS: If CPP is to be raised to a level higher than 65-70 mmHg, then it is important to recognise that the response to the intervention may be unpredictable and that the vasoactive agent used may be of importance.

Adult↗
PubMed2004

Neurofibromatosis type I: spinal neoplasia without symptoms.

Neurofibromatosis1 (NF-1) or von Recklinghausen disease is the most common of the neurocutaneous syndromes. It is characterized by presence of hamartomas in multiple organs. Inheritance is autosomal dominant but spontaneous mutations are seen in half the cases. The authors are reporting a classical case of this syndrome with spinal neoplasia which was interestingly asymptomatic. Authorities seem to agree that because the risk of developing intradural disease is significant in patients with NF-1, a routine MRI of the entire spine should be obtained.

Child↗
PubMed2004

Caudal duplication syndrome: more evidence for theory of caudal twinning.

Caudal duplication syndrome is a rare entity in which structures derived from the embryonic cloaca and notochord are duplicated to various extents. The term encompasses a spectrum and often is quoted as one type of incomplete separation of monovular twins. The authors present more evidence giving credence to caudal twining as the mechanism behind the syndrome. The authors report successful surgical management of a full-term infant with a constellation of anomalies of caudal duplication syndrome.

Abnormalities, Multiple↗
PubMed2004

Bilateral spontaneous perinephric urinomas: case report and review of the literature.

Urinoma is defined as an encapsulated collection of extravasated urine in the perirenal or paraureteral space. Urinomas in childhood are rare and usually either secondary to obstructive uropathies or due to blunt or penetrating trauma leading to injuries of the collecting system and/or ureter. Spontaneous perinephric urinomas are rare. We report the case of an 8-year-old boy with bilateral spontaneous perinephric urinomas secondary to an abnormally elevated voiding pressure with detrusor sphincter dyssynergia. The available literature on this subject is reviewed, and clinical features, pathophysiology, and treatment of this entity are discussed.

Child↗
PubMed2004

Extracellular Brain pH and Outcome following Severe Traumatic Brain Injury.

The ability to measure brain tissue chemistry has led to valuable information regarding pathophysiological changes in patients with traumatic brain injury (TBI). Over the last few years, the focus has been on monitoring changes in brain tissue oxygen to determine thresholds of ischemia that affect outcome. However, the variability of this measurement suggests that it may not be a robust method. We have therefore investigated the relationship of brain tissue pH (pH(b)) and outcome in patients with TBI. We retrospectively analyzed prospectively collected data of 38 patients admitted to the Neurosciences Critical Care Unit with TBI between 1998 and 2003, and who had a multiparameter tissue gas sensor inserted into the brain. All patients were managed using an evidence-based protocol targeting CPP > 70 mm Hg. Physiological variables were averaged over 4 min and analyzed using a generalized least squares random effects model to determine the temporal profile of pH(b) and its association with outcome. Median (IQR) minimum pH(b) was 7.00 (6.89, 7.08), median (IQR) maximum pH(b) was 7.25 (7.18, 7.33), and median (IQR) patient averaged pH(b) was 7.13 (7.07, 7.17). pH(b) was significantly lower in those who did not survive their hospital stay compared to those that survived. In addition, those with unfavorable neurological outcome had lower pH(b) values than those with favorable neurological outcome. pH(b) differentiated between survivors and non-survivors. Measurement of pH(b) may be a useful indicator of outcome in patients with TBI.

Acid-Base Equilibrium↗
PubMed2004

Direct comparison of cerebrovascular effects of norepinephrine and dopamine in head-injured patients.

OBJECTIVE: To directly compare the cerebrovascular effects of norepinephrine and dopamine in patients with acute traumatic brain injury. DESIGN: Prospective randomized crossover trial. SETTING: Neurosciences critical care unit of a university hospital. PATIENTS: Ten acutely head-injured patients requiring vasoactive drugs to maintain a cerebral perfusion pressure of 65 mm Hg. INTERVENTIONS: Patients were randomized to start the protocol with either norepinephrine or dopamine. Using an infusion of the allocated drug, cerebral perfusion pressure was adjusted to 65 mm Hg. After 20 mins of data collection, cerebral perfusion pressure was increased to 75 mm Hg by increasing the infusion rate of the vasoactive agent. After 20 mins of data collection, cerebral perfusion pressure was increased to 85 mm Hg and again data were collected for 20 mins. Subsequently, the infusion rate of the vasoactive drug was reduced until a cerebral perfusion pressure of 65 mm Hg was reached and the drug was exchanged against the other agent. The protocol was then repeated. MEASUREMENTS AND MAIN RESULTS: Mean arterial pressure and intracranial pressure were monitored and cerebral blood flow was estimated with transcranial Doppler. Norepinephrine led to predictable and significant increases in flow velocity for each step increase in cerebral perfusion pressure (57.5+/-19.9 cm x sec, 61.3+/-22.3 cm x sec, and 68.4+/-24.8 cm x sec at 65, 75, and 85 mm Hg, respectively; p <.05 for all three comparisons), but changes with dopamine were variable and inconsistent. There were no differences between absolute values of flow velocity or intracranial pressure between the two drugs at any cerebral perfusion pressure level. CONCLUSIONS: Norepinephrine may be more predictable and efficient to augment cerebral perfusion in patients with traumatic brain injury.

Adult↗