Biomedical subjects
Publications and source records attributed to K Kumar.
An osteosarcoma developed in a boy, 16 years of age, 9 years after staples had been inserted in the region of the lower femoral epiphysis. The possible association between the implant and the tumour is discussed.
A reversed-phase high-performance liquid chromatography method for the simultaneous determination of plasma concentrations of the narcotic analgesics alfentanil and fentanyl using papaverine hydrochloride as the internal standard is presented. Chromatographic separations were achieved with an Econosphere CN, 5 microns, 25 cm x 4.6 mm i.d. column and the effluent was monitored at 195 nm. The assay was linear over the clinically relevant plasma range of 2-2000 ng ml-1 for alfentanil and 2-100 ng ml-1 for fentanyl and has the sensitivity and specificity necessary to determine plasma concentrations of these compounds. Inter- and intra-day precision (RSD) for both compounds did not exceed 10% in these ranges. The assay procedure was utilized for pharmacokinetic studies of plasma concentrations in subjects receiving alfentanil and fentanyl during and after cardiac surgery. This will allow better elucidation of pharmacokinetic variables in this populace.
A reversed-phase high performance liquid chromatographic method is described for the determination of droperidol concentrations in plasma. Following extraction, separation of droperidol and the internal standard flurazepam was achieved with a Spherisorb Nitrile, 5 microns, S5CN 250 mm x 4.6 mm column at 200 nm. The mobile phase was phosphate buffer (0.05 M, pH 2.4), acetonitrile and ethanol (65:20:15, v/v/v). The assay was rapid, sensitive and linear over the range 2-4000 ng ml-1. Precision of the assay expressed as the intra- and inter-day relative standard deviations (%RSD) did not exceed 10%. Flunitrazepam, midazolam and nitrazepam were also resolved with this technique and did not interfere with droperidol or flurazepam. Resolution of all five compounds was complete in less than 6 min. The assay was used to study the pharmacokinetics of high dose droperidol infusions during and after cardiac surgery.
BACKGROUND: Spinal cord stimulation (SCS) has been used for the relief of chronic, intractable pain for over 2 decades. Recent technologic improvements in hardware have resulted in improved clinical outcome. We report our experience with epidural spinal cord stimulation for pain control of peripheral neuropathy for the past 15 years. METHODS: An analysis of our series of 276 patients revealed 30 patients diagnosed with peripheral neuropathy. The mean age of the 16 men and 14 women in the study was 62.4 years. The anatomic sources of pain included thorax, as well as upper and lower limbs. Causes of intractable pain included postherpetic neuralgia, intercostal neuralgia, causalgic pain, diabetic neuropathy, and idiopathic neuropathy. RESULTS: Nineteen patients reported relief of pain on trial stimulation and had their systems permanently implanted. At an average of 87 months' follow-up, 14 of these patients achieved long-term success in control of chronic pain (47% of all patients included in this study). Six patients reported excellent pain relief (> 75% pain relief), eight described good results (> 50% pain relief), and six had poor pain relief (< 50% pain relief). CONCLUSION: SCS is an effective therapy for pain syndromes associated with peripheral neuropathy. Causalgic and diabetic neuropathic pain seem to respond relatively well. whereas postherpetic pain and intercostal neuralgia syndromes seem to respond less favorably to the long-term beneficial effects of SCS. This information will be useful in the selection of patients with peripheral neuropathic pain who could be helped by SCS.
Immediate early genes are induced by transient global ischemia. Using immunohistochemistry we studied the effect of intraischemic hypothermia (30 degrees C) on the expression of c-fos and fos-B proteins following 10 min forebrain ischemia in the gerbil. Postischemia (PI) periods of 1 hour (h), 6 h, 1 day (d) and 2 d and nonischemic controls were examined in normothermic and hypothermic brains. In normothermic ischemic brains, marked expression of c-fos occurred in the dentate gyrus after 1 h PI which extended to CA2-4 regions by 6 h. Hypothermia hastened the time course of c-fos expression as it was expressed simultaneously in the dentate gyrus as well as CA2-4 regions after only 1 h, and by 6 h the expression remained only in the CA2-4 regions and not the dentate gyrus in hypothermic ischemic brains. There was no difference in its expression between normothermic and hypothermic brains in the 1 d and 2 d PI animals. Somewhat similar changes were noted in fos-B expression. In normothermic ischemic brains fos-B was induced in the dentate gyrus by 1 h PI, and by 6 h it extended to involve CA1-4 cells. The hypothermic ischemic brains showed faster induction of fos-B so that the dentate gyrus as well as CA1-4 regions were immunopositive at 1 h PI. There was no difference in its expression between normothermic and hypothermic brains in the subsequent PI periods of 6 h, 1 d and 2 d. The shift towards faster sequential induction of these genes by hypothermia in ischemic brains may be indicative of preservation of or faster recovery of mechanisms involved in intracellular signalling.
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The authors present a case of thoracic spinal cord compression secondary to epidural lipomatosis in an obese patient. This patient represents the 10th case of epidural lipomatosis secondary to simple obesity reported in the literature. The diagnosis is based on three criteria: 1) medical history and physical examination consistent with segmental spinal cord compression; 2) epidural fat thickness greater than 7 mm in the region of compression, based on magnetic resonance imaging (preferred) or computerized tomographic imaging; and 3) a height-to-weight ratio greater than 27.5 kg/m2. This specific correlation between epidural fat thickness measurement and calculation of height-to-weight ratio has not previously been reported. Surgical decompression through a posterior laminectomy and excision of excess epidural fat resulted in immediate reversal of the patient's symptoms. Knowledge of the association of epidural lipomatosis with obesity in the absence of glucocorticoid imbalance is important in discerning what may be an underrecognized syndrome.
A rapid survey in Delhi and surrounding areas was undertaken in September 1994, during plague outbreak in District Beed (Maharashtra) and Surat (Gujarat) to monitor rodent/flea population and to determine susceptibility status of fleas to insecticides. The five rodent species in order of their prevalence were Rattus rattus (86.06%), Mus musculus (15.33%), Suncus murinus (2.47%), Bandicoota indica (0.48%) and B. bengalensis (0.48%). Two flea species, Xenopsylla cheopis and X. astia, were captured from these rodents. The absolute flea index was found to be ranging between 0.08 to 4.0 in various localities. X. cheopis and X. astia indexes were ranging between 0.22 to 2.08 and 0.08 to 4.0, respectively. Susceptibility test results with X. cheopis collected and reared in the laboratory revealed that it is resistant to DDT and Dieldrin, tolerant to Malathion and susceptible to K-othrin (Deltamethrin).
OBJECTIVE: To assess the results of simplified sutured sacral rectopexy for complete rectal prolapse. DESIGN: Prospective study. SETTING: University hospital, India. SUBJECT: 65 patients with complete rectal prolapse treated by modified sutured sacral rectopexy. MAIN OUTCOME MEASURES: Morbidity, mortality and recurrence. RESULTS: During a follow-up of 2-10 years (mean 5.4 years) none of the patients developed a recurrence of complete prolapse of the rectum but 3(5%) developed mucosal prolapse. The incontinence improved in 12 of 16 patients (75%) and constipation improved in 5 of 6 (83.3%). CONCLUSION: We conclude that the simplified sutured sacral rectopexy is a simple operation for treating complete rectal prolapse in adults, and gives good results.
The expression of a cytoskeletal protein, beta-actin, mRNA was examined in hypothermic ischemic brains. Mongolian gerbils were subjected to forebrain ischemia by bilateral carotid occlusion of 10 min at 30 degrees C followed by normothermic reperfusion for 1 h or 6 h, 1 day or 3 days, 2 weeks or 1 month. The expression of beta-actin mRNA was determined in hypothermic controls and postischemic (PI) animals subjected to intra-ischemic hypothermia using in situ hybridization. On comparing the pattern of expression of beta-actin in hypothermic ischemic brains with that in normothermic ischemic brains, it was noted that there was no significant decline in its expression in the CA1 region of hypothermic ischemic brains as noted in the normothermic ischemic brains (reported by us previously). Only one hypothermic ischemic animal in the 2 week PI period showed marked reduction in its expression in the CA1 region. These results indicate that hypothermia leads to preservation of the expression of a cytoskeletal protein, beta-actin, in a selectively vulnerable region of the brain following ischemia.
A new technique of pulmonary vein wedge angiography to delineate pulmonary artery anatomy is described. Conventional pulmonary vein wedge angiography requires an interatrial communication--natural or created by a transseptal puncture. In retrograde pulmonary vein wedge angiography, the left atrium and pulmonary veins are entered from arterial route using a specially designed catheter. This technique can be specially utilized for patients in whom there is no interatrial communication.
Primary (without antecedent balloon dilation) Palmaz stent implantation was successfully performed in 27 consecutive patients entering with 31 obstructed subclavian arteries. Stents (n = 50) were successfully deployed, using the brachial (n = 7), femoral (n = 16), or combined (n = 8) approach, to revascularize 31 subclavian vessels [8 occluded (26%); 23 stenotic (74%)], using a 6 or 7.5 French delivery system. The indications for intervention were arm claudication in 8 patients (30%), subclavian steal syndrome in 11 patients (41%), angina pectoris secondary to impaired blood flow to the left internal mammary artery coronary bypass in 6 patients (22%), and recanalization of a left subclavian occlusion to permit central arterial access and performance of a second interventional procedure 2 patients (7%). The percent diameter stenosis improved from 85 +/- 12% to 6 +/- 7% (P < 0.001); and, the peak and mean translesion gradients decreased, respectively, from 56 +/- 35 mm Hg to 3 +/- 4 mm Hg (P < 0.01), and 29 +/- 18 mm Hg to 2 +/- 2 mm Hg (P < 0.01). Procedural complications encountered were one stent dislodgement with migration into and uneventful deployment within the right external iliac artery, and two brachial artery repairs. No acute vessel closures, deaths, myocardial infarctions, cerebrovascular accidents, transient ischemic attacks, or need for transfusions occurred. Therefore, primary subclavian artery stent deployment can be performed using low-profile sheath systems with excellent success (100%), resulting in immediate restoration of pulsatile flow, and few complications. The incidence of lesion recurrence remains for follow-up studies.
The management of three cases of coronary artery rupture is described: (1) after high-pressure balloon angioplasty following uneventful placement of three Gianturco-Roubin stents, (2) following balloon angioplasty of an occluded diagonal branch, and (3) subsequent to rotational ablation of a left main and proximal circumflex arteries. Placement of an autologous vein-covered Palmaz stent or microcoil embolic vessel occlusion solved each problem. In each case, emergency surgery was avoided; subsequent management, including anticoagulation (when indicated), was performed without incident. This is the first communication detailing correction of a coronary vessel rupture with an autologous vein-covered stent or by microcoil embolic vessel occlusion.
Intra-ischemic hypothermia has been demonstrated to be protective against ischemic neuronal injury. The present study examined the effect of moderate hypothermia on the expression of heat shock protein (HSP)-72 following transient forebrain ischemia in gerbils by immunohistochemistry. Global forebrain ischemia with concurrent moderate hypothermia (30 degrees C) was induced in gerbils by 10-minute bilateral carotid artery occlusion followed by recirculation periods of 1 hour (h), 6h, 24h, and 48h. Normothermic forebrain ischemic animals with similar recirculation periods were utilized for comparison of the HSP expression. Sham-operated normothermic and hypothermic animals were also included. 72-kDa heat shock protein immunoreactivity was demonstrated in the hippocampus and neocortex of the normothermic ischemic animals following 24h and 48h recirculation similar to that reported previously. However, the immunoreactivity was absent in the brains of the animals subjected to hypothermic ischemia or sham-operation. Only the ependymal cells were immunopositive in all hypothermic brains as was the case with all normothermic brains. The hypothermic ischemic brains showed no significant necrosis in the hippocampus. These findings suggest that the protection of ischemic neuronal necrosis conferred by intra-ischemic hypothermia is not associated with induction of HSP-72 protein and that mechanisms other then HSP-72 protein induction are likely to be responsible for this neuroprotective effect.
BACKGROUND: Rapid two-stage arterial switch operation is advocated in infants with simple transposition presenting late. Accurate assessment of left ventricular preparation is crucial to successful outcome. The role of echocardiography alone in surgical decision making remains unclear. METHODS: Seventeen patients with simple transposition (mean age, 4 months) underwent pulmonary artery banding and modified Blalock-Taussig shunt (first stage) to prepare the left ventricle for the arterial switch operation (second stage). Serial echocardiography was performed in the interval phase to assess left ventricular growth. Sixteen patients underwent arterial switch operation after a mean interval of 10.4 +/- 4 days, with 14 successful conversions. There was one mortality (5.9%) and two conversions to a Senning repair. RESULTS: In all patients a mean increase in left ventricular mass (40.8 +/- 17.8 g/m2 to 81.4 +/- 25.4 g/m2) and posterior wall thickness (3.37 +/- 0.47 mm to 4.63 +/- 0.58 mm) was recorded. Left ventricular end-diastolic internal diameter increased in all except the two switch failures. In all the successful cases the left ventricle had assumed a circular shape on cross-section with the interventricular septum contracting in synergy with the left ventricular mass. In the two failures, however, the interventricular septum had remained flat. CONCLUSIONS: Echocardiography can be used reliably in surgical decision making in rapid two-stage arterial switch operation. Increase in left ventricular mass, left ventricular posterior wall thickness, and left ventricular end-diastolic internal diameter toward normal combined with an acquisition of circular left ventricular configuration with the interventricular septum contracting in synergy with the left ventricular mass appear to best predict successful outcome.
The time course of mRNA expressions of two cytoskeletal proteins, beta-actin and alpha-tubulin, was studied by Northern blot analysis and in situ hybridization in the same gerbil brains at various periods of recirculation following 10 min of forebrain ischemia. On Northern blot analysis, beta-actin mRNA in the forebrain showed increase after 6 h and 24 h recirculation. There was wide variation in its expression 3 days postischemia (PI), and by 7 days PI it had returned to control. The alpha-tubulin mRNA in the forebrain was shown to be reduced 6 h PI in our previous study. In the present analysis of Northern blots of delayed postischemic periods, there was no significant change in its expression even though there were variations. In situ hybridization revealed a decline in the mRNA expressions of both alpha-tubulin and beta-actin in the CA1 region as early as 6-24 h PI with the reductions being prominent at 3 days PI. By 7 days PI, beta-actin was only faintly visible while alpha-tubulin was completely absent in the CA1 region. Neither RNA was detectable in CA1 1 month PI. The heat shock-70 protein was expressed by 1 h PI, and it continued to be expressed up to 24 h, returning to control by 3 days PI. These results indicate that ischemia inhibits mRNA expressions of cytoskeletal protein in the selectively vulnerable region of the brain, i.e. CA1. The time course of the reduction of the two mRNAs coincides with delayed neuronal death suggesting that the cytoskeletal proteins may play important roles in selective postischemic neuronal injury.
RATIONALE AND OBJECTIVES: The authors studied the long-term distribution of gadolinium (Gd) in mice and rats after the administration of four commercially available magnetic resonance imaging contrast media. The goals were to determine any possible product dissociation in vivo and to evaluate the effects that product excipients had on the tissue distributions. METHODS: Gadolinium-153 (153Gd)-labeled gadopentetate (Magnevist), gadoteridol (ProHance), gadoterate (Dotarem), and gadodiamide (Omniscan) were administered intravenously to mice (0.48 mmol/kg) and rats (0.1 mmol/kg). At various times up to 14 days posttreatment, the residual 153Gd was measured in selected tissues. The tissue distributions obtained were used to make intra- and interchelate distribution evaluations and comparisons regarding tissue clearance and any possible in vivo dissociation of the Gd chelates. RESULTS: Differences were found among the chelates studied relative to the amounts of residual 153Gd present in tissues known to sequester free Gd, particularly in liver and femur at 7 and 14 days after administration, in both mice and rats. The pattern of the 153Gd distribution suggested that the linear chelates, gadopentetate and gadodiamide, dissociated in vivo resulting in more 153Gd present in bone and liver at the longer residence times than in the subjects injected with the macrocyclic chelates, gadoteridol and gadoterate. The only excipient found to affect the distribution profile was calcium(DTPA-BMA); this excipient in formulated gadodiamide decreased the amounts of residual Gd measured in whole body, bone, and liver in mice compared with levels obtained when gadodiamide was injected alone. CONCLUSIONS: The molecular feature found to be most important in differentiating the four chelates evaluated is the presence or absence of a macrocyclic structure. The Gd chelates containing this structure, gadoteridol and gadoterate, have the lowest residual Gd at long residence times in both mice and rats. The order of residual whole body Gd at 14 days (lowest to highest) was: gadoteridol integral of gadoterate < or = gadopentetate << gadodiamide. The only excipient that affected the biodistribution was found in the gadodiamide formulation where the addition of 5% calcium (DTPA-BMA) reduced residual Gd to just less than 10 times greater than that found for the macrocyclic chelates with the lowest residual Gd, gadoteridol and gadoterate.
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