Biomedical subjects
Publications and source records attributed to A Saxena.
Traumatic injuries to the rectum although uncommon can result in virulent complications and even death. Diverting colostomy, presacral drainage, distal wash out and rectal repair, when feasible, have become the standard treatment for rectal injuries. We report an unusual case of rectal injury resulting in anorectal avulsion from skin and surrounding tissues.
Peptic perforation is a serious complication of peptic ulcer disease. The defect in the intestinal wall usually does not present a difficult technical problem of surgical management, in most cases perforation can be closed primarily. On rare occasions an extremely large defect (giant peptic perforation - defined as any perforation greater than 2.5 cm in size) cannot be closed by these simple techniques. Modalities of treatment advocated for such an ulcer over the years are: free omental plug in the form of a mushroom; serosal patch technique; jejunal pedicle graft, partial gastrectomy, and finally the possible addition of proximal gastrojejunostomy. The omental plug is a simple procedure which does not require expertise and can even be performed in a very short time by a trainee general surgeon in a seriously ill patient in emergency. We review 7 cases of giant peptic perforations closed by a free omental plug.
Surgical bypass for the palliation of dysphagia in patients with unresectable oesophageal carcinoma continues to be an option in developing countries, as the cost of a good quality endo-prosthesis is well beyond the means of most patients. One such case is presented in which an in-continuity fundic bypass (without resection of the lesser curvature and cardia, thereby not disconnecting the oesophago-gastric junction) was made with gratifying results with regard to quality of life. Awareness of this previously unreported procedure is important because it adds to the armamentarium of surgeons wanting to provide palliation for dysphagia and aspiration in patients with unresectable carcinoma of the oesophagus.
A retrospective review of 63 Magnetic Resonance Image studies (yielding 86 ankles) was conducted to find the incidence of the plantaris tendon. Radiographically, the plantaris tendon was visualized 62.8% of the time. Surgical confirmation of this tendon during 18 achilles surgeries yielded 13 "true positives" and 4 "true negatives". Sensitivity was 92.8%; specificity and positive predictive value was 100%, respectively. As a comparison, forty cadaveric specimens were evaluated as well, with the incidence of the plantaris found to be 97.5%. These findings may be useful when considering MRIs as a screening tool for the presence of plantaris tendon. When axial images were 4 mm or less, the plantaris tendon was more easily visualized. A Chi-squared test examining for differences of axial sections greater than 4 mm was not significant. (P=0.2). This is important if one is to use MRI to screen for the plantaris (for graft purposes).
BACKGROUND AND AIM OF THE STUDY: The aim of the study was to report on the long-term results of aortic valve balloon dilatation (AVBD) for congenital valvular aortic stenosis in children and young adults. METHODS: The records of 74 patients (age range: 1-20 years) who underwent AVBD at a single center were analyzed retrospectively. Special attention was paid to factors that might influence long-term outcome. RESULTS: The procedure was successful in 71 patients (96%). The mean (+/- SD) reduction in peak-to-peak systolic gradient (PSG) was 68.7 +/- 13.5%. No patient required immediate surgical intervention. Survival after dilatation was 100% at 12 years. At follow up (mean 5.5 +/- 2.9 years; range: 2-12 years), 20% of patients had restenosis and 21% had significant aortic regurgitation (AR) (grade > or = 3). Reintervention was performed in 14% of patients. Severity of AR and high residual stenosis immediately after AVBD were associated with the late event rates. The actuarial intervention-free rates at five, seven and 12 years were 92.9%, 84.4% and 60%, respectively. CONCLUSION: AVBD is a useful, albeit palliative, procedure for children and young adults with significant congenital valvular aortic stenosis.
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The original Jones Criteria as proposed by Dr. T. Duckett Jones have been modified four times and the updated revised criteria were published in 1992. According to this latest publication major manifestations are carditis, polyarthritis, chorea, erythema marginatum and subcutaneous nodules. Minor manifestations include fever, arthralgia and laboratory findings of elevated erythrocyte sedimentation rate, C-reactive protein and prolonged PR interval on ECG. For making a diagnosis of acute rheumatic fever, two major, or one major and two minor manifestations must be accompanied by supporting evidence of antecedent group A streptococcal infection in the form of positive throat culture or elevated or rising anti-streptolysin titre. The updated guidelines also highlighted a subgroup of "exceptions to Jones Criteria" for patients with chorea, indolent carditis and previous history of rheumatic fever or "rheumatic heart disease". Role of echocardiography has not been defined in these modifications but may be important, as clinical detection of soft murmurs may be difficult due to tachycardia. Doppler and color flow mapping is more sensitive in picking up minor digress of valvular regurgitation. Several studies have confirmed that the yield of carditis with valvular regurgitation increased with use of echocardiography in patients with acute rheumatic fever. Also echocardiography is of great help in mixed valve lesions to determine the severity of each lesion. Other abnormalities detected on echocardiography in acute carditis include prolapse of the valve, focal nodular thickening of leaflets and pericardial effusion. Jones Criteria are guidelines to assist the physician and should not be substituted for clinical judgement as strictly following them may result in underdiagnosis of this disease in our country.
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Reactivation of organophosphate (OP)-inhibited acetylcholinesterase (AChE) is a key objective in the treatment of OP poisoning. This study with native, wild-type, and mutant recombinant DNA-expressed AChEs, each inhibited by representative OP compounds, establishes a relationship between edrophonium acceleration of oxime-induced reactivation of OP-AChE conjugates and phosphoryl oxime inhibition of the reactivated enzyme that occurs during reactivation by pyridinium oximes LüH6 and TMB4. No such recurring inhibition could be observed with HI-6 as the reactivator due to the extreme lability of the phosphoryl oximes formed by this oxime. Phosphoryl oximes formed during reactivation of the ethoxy methylphosphonyl-AChE conjugate by LüH6 and TMB4 were isolated for the first time and their structures confirmed by (31)P NMR. However, phosphoryl oximes formed during the reactivation of the diethylphosphoryl-AChE conjugate were not sufficiently stable to be detected by (31)P NMR. The purified ethoxy methylphosphonyl oximes formed during the reactivation of ethoxy methylphosphonyl-AChE conjugate with LüH6 and TMB4 are 10- to 22-fold more potent than MEPQ as inhibitors of AChE and stable for several hours at pH 7.2 in HEPES buffer. Reactivation of both ethoxy methylphosphonyl- and diethylphosphoryl-AChE by these two oximes was accelerated in the presence of rabbit serum paraoxonase, suggesting that organophosphorus hydrolase can hydrolyze phosphoryl oxime formed during the reactivation. Our results emphasize that certain oximes, such as LüH6 and TMB4, if used in the treatment of OP pesticide poisoning may cause prolonged inhibition of AChE due to formation of phosphoryl oximes.
We examined the role of A328(F330) in the binding of various inhibitors to cholinesterases (ChEs) using human butyrylcholinesterase (BChE) mutants to determine if the conclusions drawn from studies with acetylcholinesterase (AChE) mutants could be extended to BChE. For huperzine A and edrophonium, the results obtained with AChE mutants could be directly correlated with those obtained with native ChEs and site-specific mutants of human BChE. Inhibition studies of ethopropazine with BChE mutants, where A328 was modified to either F or Y, suggested that A328 was not solely responsible for the selectivity of ethopropazine. Volume calculations for the active-site gorge showed that the poor inhibitory activity of ethopropazine towards AChE was due to the smaller dimension of the active-site gorge. The volume of the BChE active-site gorge is approximately 200 A3 larger than that of the AChE gorge, which allows the accommodation of ethopropazine in two different orientations as demonstrated by rigid-body refinement and molecular dynamics calculations. These results suggest that, although the overall scaffolding of the two enzymes may be highly similar, the dimensions and the micro-environment of the gorge play a significant role in determining the selectivity of substrate and inhibitors for ChEs.
We examined the role of edrophonium in the acceleration phenomenon using mouse wild-type and mutant D74N AChE inhibited with 7-(O,O-diethyl-phosphinyloxy)-1-methylquinolinium methylsulfate (DEPQ). With DEPQ-inhibited wild-type mouse acetylcholinesterase (AChE), the reactivation kinetic profile demonstrated one-phase exponential association only when 2-[hydroxyimino methyl]-1-methylpyridinium chloride (2-PAM) and 1-(2-hydroxy-iminomethyl-1-pyridinium)-1-(4-carboxy-aminopyridi nium)-dimethyl ether hydrochloride (HI-6) were used as reactivators. When 1,1[oxybis-methylene)bis[4-(hydroxyimino)methyl] pyridinium dichloride (LüH6) and 1,1-trimethylene bis(4-hydroxyimino methyl) pyridinium dichloride (TMB4) were used, the reactivation kinetic profile was biphasic in nature. Edrophonium had no effect on reactivation by 2-PAM and HI-6, but significantly accelerated LüH6- and TMB4-induced reactivation of DEPQ-inhibited wild-type mouse AChE. Comparison of the initial and overall reactivation rate constants with five oximes indicated that acceleration by edrophonium may be due to the prevention of re-inhibition of the reactivated enzyme by the phosphorylated oxime (POX) produced during the reactivation. With LüH6 and TMB4, about 2.5-fold increase in the reactivation rate constants was observed in the presence of edrophonium, but little or no effect was observed with the other three oximes. The initial reactivation rate constants were 5.4- and 4.2-fold of the overall rate constants with LüH6 and TMB4 as reactivators respectively, however, very little change was found between the initial and overall rate constants with the other three oximes. In experiments with D74N AChE, for which the inhibition potency of charged organophosphate (OP) was two to three orders less than wild-type enzyme, edrophonium had no effect on the reactivation by LüH6 and TMB4 and the time courses of reactivation were monophasic. The data from mutant enzyme substantiate the involvement of edrophonium in protecting POX re-inhibition of reactivated enzyme formed during the reactivation of OP-inhibited AChE.
The ability of stoichiometric scavengers, such as ChEs, to protect against a variety of OP agents has been demonstrated in several in vivo models. To improve the detoxification of OP agents by ChEs, several approaches have been recently used to increase the stoichiometry, stability, and in vivo effectiveness of ChEs as OP scavengers. For example, the in vitro stoichiometric neutralization of sarin by AChE was increased from 1:1 to 3200:1 by the addition of the oxime HI-6, while the in vivo stoichiometry was increased to 57:1 in mice by HI-6. The aging rate of soman-inhibited mouse AChE was reduced 12-fold in a mutant AChE (E202Q) which resulted in a two-fold increase in oxime-assisted detoxification of soman. To improve the duration of scavenger protection provided by ChEs, the mean residence times of five tissue-derived and two recombinant ChEs injected i.v. in mice were compared with their oligosaccharide profiles. The mean residence times of these ChEs were found to increase with molecular weight and with the levels of oligosaccharide sialylation. The stability of AChE in non-physiological environments was improved by immobilizing it in a polyurethane foam matrix that allowed AChE to retain enzymatic activity at high temperature (75 degrees C) where soluble enzyme denatured. These developments in scavenger technology have improved the in vivo protection provided by OP scavengers and extended their applicability to provide external decontamination of chemical agents and pesticides.
Malignant glial tumors (anaplastic astrocytomas and glioblastomas multiforme) arise mostly either from the progression of low grade precursor lesions or rapidly in a de novo fashion and contain distinct genetic alterations. There is, however, a third subset of malignant gliomas in which genetic lesions remain to be identified. Following surgical resection, all gliomas appear to have an inherent tendency to recur. Comparative molecular analysis of ten primary malignant gliomas (three anaplastic astrocytomas and seven glioblastomas multiforme) with their recurrences identified two distinct subgroups of recurrent tumors. In one group, primary tumors harbored genetic aberrations frequently associated with linear progression or de novo formation pathways of glial tumorigenesis and maintained their genetic profiles upon recurrence. In the other subset with no detectable known genetic mutations at first presentation, the recurrent tumors sustained specific abnormalities associated with pathways of linear progression or de novo formation. These included loss of genes on chromosomes 17 and 10, mutations in the p53 gene, homozygous deletion of the DMBTA1 and p16 and/ or p15 genes and amplification and/or overexpression of CDK4 and alpha form of the PDGF receptor. Recurrent tumors from both groups also displayed an abnormal expression profile of the metalloproteinase, gel A, and its inhibitor, TIMP-2, consistent with their highly invasive behavior. Delineation of the molecular differences between malignant glioblastomas and their subsequent recurrences may have important implications for the development of rational clinical approaches for this neoplasm that remains refractory to existing therapeutic modalities.
Angiomyolipoma, which consists of three intimately intermixed components, smooth muscle, blood vessels, and adipose tissue, is variably considered a hamartoma, a choristoma or a true neoplasm. This study has investigated the clonality of sporadic angiomyolipomas in seven women, each with a single lesion, by determining the pattern of X-chromosome inactivation. Polymerase chain reaction (PCR) amplification of the highly polymorphic human androgen receptor gene (HUMARA) was performed on the DNA extracted from the paraffin-embedded lesional tissue microdissected to sample the admixed smooth muscle and blood vessel component (SMC/BV) and the adipose tissue component. All seven patients were heterozygous for HUMARA polymorphism upon amplification of undigested DNA from non-lesional tissue and were therefore informative for further analysis. In all patients, lesional DNA, representative of the components, was predigested with HpaII restriction enzyme for amplification of the methylated allele. In six patients, the lesions were clonal, while in one, polyclonal. The polyclonal lesion was small and had less than 20 per cent SMC/BV component. Microdissected SMC/BV component was clonal in 6/7 lesions; the scanty SMC/BV in the remaining lesion did not yield amplifiable DNA. Microdissected adipose tissue was polyclonal in all seven lesions. Angiomyolipomas are three clonal lesions due to a clonal smooth muscle cell and blood vessel component, while the polyclonal adipose tissue is probably metaplastic or reactive.
We describe an 11-year-old girl with tetralogy of Fallot and absent pulmonary valve, who on selective coronary angiography was found to have extrinsic compression of the left main coronary artery by the aneurysmally dilated pulmonary artery. This abnormality has not been reported previously.
PURPOSE: To study the effects of a systemic thermal injury on the pulmonary vasculature with and without inhibitors of lipid peroxidation (U74389G). METHODS: In a prospective, placebo control, randomized, and blinded multi-group study, burn shock was induced by scalding thermal injury (65C) to 35% body surface area in rabbits (n = 28). Hemodynamics and gas exchange were followed for 240 min post burn in four groups: No Burn, Burn-Control, Burn-U74 (10 mg.Kg-1 U74389G), No Burn-U74 (10 mg.Kg-1 U74389G). RESULTS: Scald resulted in early pulmonary injury as measured by increased pulmonary vascular resistance in the pooled Burn group compared with the No Burn groups (942 +/- 358 vs 605 +/- 255 dynes.sec-1.cm-5 respectively, P < 0.05). These pulmonary changes were associated with alveolar sequestration of leukocytes (4.8 +/- 2.9 vs 17.7 +/- 6.0 cells x 10(9).L-1, P < 0.05) in the No Burn and Burn groups respectively. Histological evidence of decreased neutrophil sequestration after scald injury was present in U74 treated animals (3+ vs 2+, P < 0.05 in the Burn and No Burn groups respectively and 2+ vs 2+, P > 0.05 in the Burn-U74 and No Burn-U74 groups respectively) although bronchial alveolar lavage still demonstrated neutrophil sequestration (5.3 +/- 2.5 vs 12.2 +/- 3.3 cell 10(9).L-1, P < 0.05 in No Burn-U74 and Burn-U74 groups respectively). Similarly, circulating white blood cells were increased in the Burn group but not Burn-U74 group four hours post burn. The increase in pulmonary vascular resistance after burn was not altered by administration of U74. CONCLUSIONS: Systemic burn results in early pulmonary vascular changes associated with leukocyte sequestration. After scald injury administration of lazaroids (U744389G) did not lessen pulmonary vascular resistance changes but did reduce neutrophil sequestration.
BACKGROUND: Corrective surgery for total anomalous pulmonary venous connection in infancy still carries high morbidity and mortality rates in developing countries. The present study evaluates the factors responsible for it. METHODS: Seventy-three infants were operated on for total anomalous pulmonary venous connection from January 1987 through October 1997. Age ranged from 5 days to 12 months (mean, 3.9+/-0.24 months), with 10 (13.7%) patients younger than 1 month old. Patient weight varied from 2.0 to 5.2 kg (mean, 3.7+/-0.27 kg). Most (90.5%) patients were small for their ages (< 50th percentile). Anomalous connection was supracardiac in 42 (57.5%), cardiac in 18 (24.7%), infracardiac in 4 (5.5%), and mixed in 9 (12.3%) patients. Thirty-five patients had obstructed drainage. Preoperatively, 30 patients received antibiotic therapy for respiratory tract infection, 3 patients had balloon atrial septostomy, and 4 patients required mechanical ventilation. Fifteen patients (20.5%) were operated on as an emergency procedure. For supracardiac and infracardiac connections, a posterior approach was used for anastomosis. In cardiac type, coronary sinus was unroofed and the resultant defect along with atrial septal defect was closed with a single patch. RESULTS: The operative mortality rate was 23.3% (17 of 73). Pulmonary hypertensive crisis was the cause of death in 10 patients. Emergency operation and weight less than the 25th percentile were the important risk factors for operative mortality. Young age (< 1 month) and type of drainage did not affect the mortality. Follow-up ranged from 1 to 108 months (mean, 56.4+/-26.0 months). There were two late deaths. The actuarial survival (Kaplan Meier) at 9 years was 72.87%+/-5.39%. CONCLUSION: Failure of early recognition, and thus delayed referral, accounted for onset of cardiac cachexia, respiratory tract infection, and severe pulmonary hypertension, which had a major effect on unfavorable outcome.