PubMed Health⌕ Search

Biomedical subjects

S Aggarwal

Publications and source records attributed to S Aggarwal.

At least 37 records · Page 2Linked to original sources
PubMed2001

Intracardiac thrombus formation and pulmonary thromboembolism immediately after graft reperfusion in 7 patients undergoing liver transplantation.

Intravascular and/or intracardiac thrombus formation followed by pulmonary thromboembolism with right ventricular dysfunction immediately after graft reperfusion during orthotopic liver transplantation (OLT) is described in 7 patients. This complication may have been related to excessive activation of the coagulation system by graft reperfusion, which overwhelmed anticoagulation mechanisms and was disproportionate to fibrinolysis. Activation of the coagulation system may be more pronounced in patients who receive less than optimal grafts, require massive transfusion, or have septic complications at the time of OLT. It is unclear whether antifibrinolytic therapy during the anhepatic stage had a role. Transesophageal echocardiography was useful in diagnosing and managing intracardiac thrombus and pulmonary thromboembolism.

Adult↗
PubMed2001

Acinar cells of the pancreas are a target of interleukin-22.

Interleukin-22 (IL-22) (also reported as IL-10-related T cell-derived inducible factor, IL-TIF) is a recently identified cytokine found to signal through a receptor comprising the class II cytokine receptor family members IL-10Rbeta/CRF2-4 and IL-22R. Previous work has established that IL-10Rbeta, also a component of the IL10R complex, exhibits a broad distribution of mRNA expression. Here, we observe that IL-22R exhibits a restricted expression pattern, with highest levels of mRNA expression in pancreas and detectable expression in multiple other tissues, particularly liver, small intestine, colon, and kidney. We find that isolated primary pancreatic acinar cells and the acinar cell line 266-6 respond to IL-22 with activation of Stat3 and changes in gene transcription. IL-22 mediates robust induction of mRNA for pancreatitis-associated protein (PAP1)/Reg2 and osteopontin (OPN). PAP1 is a secreted protein related to the Reg family of trophic factors and was initially characterized as a protein elevated in pancreatitis. In vivo injection of IL-22 resulted in rapid induction of PAP1 in pancreas, a response not observed in mice deficient in IL-10Rbeta. These results support the conclusion that IL-10Rbeta is a required common component of both the IL-10 and IL-22 receptors and suggest that IL-22 may play a role in the immune response in pancreas.

Acute-Phase Proteins↗
PubMed2000

Interleukin (IL)-22, a novel human cytokine that signals through the interferon receptor-related proteins CRF2-4 and IL-22R.

We report the identification of a novel human cytokine, distantly related to interleukin (IL)-10, which we term IL-22. IL-22 is produced by activated T cells. IL-22 is a ligand for CRF2-4, a member of the class II cytokine receptor family. No high affinity ligand has yet been reported for this receptor, although it has been reported to serve as a second component in IL-10 signaling. A new member of the interferon receptor family, which we term IL-22R, functions as a second component together with CRF2-4 to enable IL-22 signaling. IL-22 does not bind the IL-10R. Cell lines were identified that respond to IL-22 by activation of STATs 1, 3, and 5, but were unresponsive to IL-10. In contrast to IL-10, IL-22 does not inhibit the production of proinflammatory cytokines by monocytes in response to LPS nor does it impact IL-10 function on monocytes, but it has modest inhibitory effects on IL-4 production from Th2 T cells.

Amino Acid Sequence↗
PubMed2000

Measurement of internal stresses via the polarization in epitaxial ferroelectric films

The relations between electrical and mechanical properties of constrained ferroelectric films are analyzed. It is shown that the internal stresses and the elastic constants can be determined through the measurement of the electrical response. The change in the polarization is proportional to internal stresses due to film-substrate misfit, whereas the linear electrical and electromechanical responses to external field do not depend on the misfit and are determined by the film constraint. The theoretical results are successfully applied to PbZr 0.2Ti 0.8O (3) films on (001) LaAlO (3) substrate which exhibit a considerable increase in the saturation polarization due to epitaxial stresses. Significant recovery in the piezoelectric constant and susceptibility is theoretically predicted and experimentally verified for specific film configurations which reduce the degree of constraint. The concept presented in this Letter can be expanded to constrained ferromagnetic and superconductor films.

Journal Article↗
PubMed2000

Spontaneous ordering of oxide nanostructures

We report the spontaneous formation of uniformly distributed arrays of "tips" (tall conical hillocks) upon oxidation of palladium (Pd) thin films. The formation of the palladium oxide tips depended on the thickness and granularity of the Pd film and on annealing and oxidation conditions. As the Pd film thickness increased from 40 to 200 nanometers, the average height of the tips increased from 0.5 to 1.2 micrometers, their height distribution became broader, and their density decreased from 55 x 10(6) to 12 x 10(6) per square centimeter. Enhanced photoelectron emission from locations corresponding to the tips suggests their possible use in field emission applications.

Journal Article↗
PubMed2000

A minimal critical region of the 8p22-23 amplicon in esophageal adenocarcinomas defined using sequence tagged site-amplification mapping and quantitative polymerase chain reaction includes the GATA-4 gene.

The incidence of esophageal adenocarcinomas has increased greatly over the past 20 years. The genetic alterations associated with this disease, however, remain largely unknown. We identified recently a novel amplicon at 8p22-23 in esophageal adenocarcinomas using the restriction landmark genomic scanning two-dimensional gel technique. Four known genes within or near this amplicon were initially characterized. The cathepsin B (CTSB) gene was found to be amplified in 13% of esophageal tumors. CTSB was shown previously to be overexpressed without amplification in many other human cancers. An approach termed sequence tagged site-amplification mapping has been implemented in the present study, allowing the 8p22-23 amplicon to be narrowed from 12 cM to a <2-cM minimal amplified area located between markers D8S552 and D8S1759. The CTSB gene maps within this region. To identify other cancer-related candidate genes in this region, a positional candidate gene approach was subsequently applied to characterize this minimal critical region. An expressed sequence tag (EST), which was included in the minimal critical region, demonstrated both amplification and overexpression. This EST and the extended sequence from the EST were determined to be a novel sequence in the 3' untranslated region of the human GATA-4 gene. GATA-4, a member of a zinc finger transcription factor family, was confirmed to be amplified and overexpressed in esophageal adenocarcinomas and was localized within <0.5 kb from CTSB. Furthermore, amplification of 8p22-23 was detected in one of eight gastric cardia adenocarcinomas but was not observed in either human lung adenocarcinomas (n = 39) or in esophageal squamous cell carcinomas (n = 24). The relatively high frequency of the 8p22-23 amplification in esophageal (13.6%) and gastric cardia (12.5%) adenocarcinomas may indicate a specificity of this amplicon for tumors of gastroesophageal origin.

Adenocarcinoma↗
PubMed2000

Phrenic nerve palsy: a rare complication of indwelling subclavian vein catheter.

The use of central venous catheters as access for hemodialysis has become common in children with end-stage renal disease. Phrenic nerve palsy is an unusual complication of this procedure. We report a case of delayed right diaphragmatic palsy due to phrenic nerve damage resulting from an indwelling right subclavian catheter in a 3-year-old child.

Catheters, Indwelling↗
PubMed2000

Role of biomolecules from human renal stone matrix on COM crystal growth.

Human renal calculi surgically removed from kidney stone patients were obtained and chemically analysed. Stones with CaOx (calcium oxalate) as the major component were washed in 0.15 M NaCl with gentle stirring for 48 h and then pulverised to a fine powder. The powder was extracted with 0.05 M EGTA, 1 mM PMSF and 1% beta-mercaptoethanol for 4 days at 4 degrees C, the suspensions and the supernatants obtained were filtered through an Amicon Model 200 apparatus (mol. wt. cut off of 10,000 daltons) under nitrogen at 40 p.s.i. and concentrated to a known volume. The method of Nakagawa et al. [7] was employed to study the ability of > 10 kDa fractions to influence COM growth using metastable solution of CaCl2 and Na2C2O4 containing traces of 14C-oxalic acid. Potent biomolecules having the ability to influence CaOx precipitation were subjected to isolation, purification and characterization. Standard biochemical procedures, e.g. ultracentrifugation, ion-exchange chromatography, molecular sieve chromatography and SDS-PAGE, etc., were employed. Results revealed that human renal calculi extract contains biomolecules that can inhibit as well as stimulate the growth of preformed COM (calcium oxalate monohydrate) crystals. Most potent stimulator of CaOx growth was found to have a molecular weight of 66 kDa.

Adult↗
PubMed2000

TNF-alpha-induced apoptosis in neonatal lymphocytes: TNFRp55 expression and downstream pathways of apoptosis.

Previously we have shown decreased Fas-mediated apoptosis in cord blood lymphocyte subsets. In this study, we compared tumor necrosis factor (TNF)-alpha-induced apoptosis in T lymphocytes and their subsets between cord blood and peripheral blood from healthy young controls. The expression of TNF receptor I (TNFR-I) was assessed by flow cytometry and quantitative RT-PCR. The expression of adapter molecules TNF receptor-associated death domain (TRADD), Fas-associated death domain (FADD) and TNF-associated factor-2 (TRAF-2) and caspase 3 was analyzed by Western blotting. The activity of caspase 3 and caspase 8 was measured by colorimetric assay. The susceptibility of CD4+ and CD8+ T cells to TNF-alpha-induced apoptosis was measured by terminal deoxytidyl transferase-mediated dUTP nick end labelling (TUNEL) assay. Both CD4+ and CD8+ T cell subsets from cord blood demonstrated decreased susceptibility to TNF-alpha-induced apoptosis that was associated with decreased activation of both caspase 8 and caspase 3 as compared to T cell subsets in peripheral blood. Furthermore, expression of TNFR-I, TRADD and caspase 3 was decreased in cord blood lymphocytes as compared to peripheral blood lymphocytes. The significance of these observations is discussed.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Gamma knife radiosurgery for the treatment of brain metastases.

One hundred and ninety-three patients with brain metastases from various primary sites received Gamma Knife radiosurgery (GKR) from July 1992 to August 1997 and were reviewed to evaluate their clinical outcome. Survival follow-up was available on 173 patients. Whole-brain radiation therapy was also administered to 148 of these patients. The median survival was 13.1 months from initial detection of brain metastases, and 7.5 months from GKR. Univariate and multivariate analyses were performed to determine prognostic factors that influenced survival following GKR. Enhanced survival is observed in patients with radiosensitive tumor types, supratentorial tumor, history of brain tumor resection, controlled primary site, and absent extracranial metastases. Local lesion control was obtained in 82% of the patients according to their last follow-up MRI scan. GKR is an effective means of treating patients with brain metastases.

Adult↗
PubMed2000

Infusion of an antialpha4 integrin antibody is associated with less neoadventitial formation after balloon injury of porcine coronary arteries.

BACKGROUND: The alpha4beta1 (or very late antigen-4 [VLA-4]) integrin is thought to play a role in inflammatory processes, mediating mononuclear leukocyte infiltration. The adventitial response to balloon injury is an important determinant of neointimal formation and arterial remodelling. OBJECTIVES: To determine whether the monoclonal antibody hHP1/2 directed against the human alpha4-integrin subunit decreases neoadventitial formation and subsequent luminal narrowing following balloon injury. DESIGN: Randomized, double-blind, placebo controlled study. SETTING: Tertiary care, Canadian university hospital vascular biology laboratory. ANIMALS AND METHODS: In 16 pigs, two coronary arteries were injured with an oversized balloon, while a third coronary artery was designated as an uninjured control vessel. One hour before balloon injury, 5 mg/kg of hHP1/2 was administered to eight animals, while another eight animals received an infusion of a saline placebo. Animals were killed three and 14 days following balloon injury. MAIN RESULTS: Administration of hHP1/2 resulted in an immediate decrease in circulating monocyte and lymphocyte counts. These parameters returned to normal within three days. There was a decrease in neoadventitial formation 14 days after arterial injury in pigs treated with hHP1/2 compared with controls (2.26+/-0.77 versus 3.42+/-1.01 mm, respectively, P=0.04). There was a loss of lumen area between days 3 (4.33+/-1.09 mm2) and 14 (3.09+/-0.38 mm2, P=0.02) after balloon injury in pigs treated with saline, but not in the pigs treated with hHP1/2. CONCLUSIONS: Administration of an antibody to the alpha4-integrin subunit is associated with less neoadventitial formation and less lumenal narrowing after balloon injury. This novel therapy may play an important role in modulating arterial remodelling and thereby may reduce restenosis following percutaneous coronary interventions in humans.

Angioplasty, Balloon, Coronary↗
PubMed2000

Treatment margins for prostate brachytherapy.

The purpose of this article was to determine what planned treatment margin (TM) would allow for implant-related prostate volume changes and still achieve an adequate periprostatic cancercidal dose. Twenty consecutive, unselected patients who underwent (125)I implantation (144 Gy prescription dose) were studied. The treated volume (TV) was calculated as the volume encompassed by the 144 Gy isodose distribution. A post-implant computed tomography scan was obtained the following day, using 5-mm images at every 5 mm. The distances between the prostate margin (GTV) and TV were determined by measuring the distance between the ultrasound-defined prostatic margin and the prescription isodose, perpendicular to the prostatic margin. The lateral, anterior, and posterior TM margins were determined at the base, mid-level, and apex of the prostate. The pre-implant TV was nearly twice as large as the GTV, ranging from 36 to 199 mL (median, 73 mL). The anterior, lateral, and posterior planned TMs varied substantially between patients, due to lack of a consistent policy the magnitude of the CTV and the acceptable CTV-to-TV distance. For all measurement points, the median planned treatment margin was 3 mm (range, -16 mm to 14 mm). Overall, there was only a loose correlation between pre- and post-implant treatment margins primarily due to variable, implant-related prostatic dimensional changes. Patients with a greater implant-related volume increase tended to have smaller post-implant treatment margins. The post-implant TMs were negatively correlated with dimensional changes, and the negative correlation was most marked for the anterior and posterior TMs due to predominant anterior-posterior dimensional increase. As expected, the post-implant target coverage was higher when larger planning TMs were used, but the correlation was loose due to the unpredictable, highly variable degree of implant-related volume increase. We currently are using 5-mm TMs around the GTV, as identified on pre-implant transrectal ultrasonography or computed tomography. However, the poor correlation between planned and actual post-implant TMs call into question any attempt to make a rational recommendation regarding optimal TMs.

Brachytherapy↗
PubMed2000

Transfer of sick children by air.

The annual growth rate of air traffic is increasing at the rate of about 7% all over the world. Children and adolescents make a significant chunk of travelling population. Some of the neonates too take to civil air and travel under various circumstances. Others travel for the reasons of medical air evacuation and better treatment at some specialized tertiary care centers, within India or abroad or simply as medical emergency. With the increasing availability of air taxis and air ambulances, it has become necessary for the pediatricians to know the consequences and potential hazards of transfer of the sick by air, lest they lose their patients unintentionally despite professional proficiency. Air evacuation of sick child is a highly specialized job, much different from an evacuation by any fast car ambulance. The paper discusses the general impact of aviation stresses in civil aviation with special reference to sick neonates, children and adolescents, and provides general guidelines, which could be applied to any particular clinical condition with knowledge of underlying physiological processes and anticipated alterations in cabin environment. It also brings out the issues of proper pre-flight assessment, fitness to undertake air transfer, general handling of patient under transfer, desirable onboard procedures, do s and don ts during air transfer, limitations of conventional neonatal/child resuscitation kits, available medical support in aircraft cabins, proper use of hardware including physiology monitoring systems, permissible specialized medical aids, and the requirement and use of equipment during air evacuation. The importance of high awareness and preventive measures is reiterated.

Air Ambulances↗
PubMed2000

Age-related retinal pigment epithelium and Bruch's membrane degeneration in senescence-accelerated mouse.

PURPOSE: To investigate age-related changes in the retinal pigment epithelium (RPE), Bruch's membrane, and choriocapillaris in the senescence-accelerated mouse (SAM). METHODS: The external and eyecup features and light and electron microscopic findings were examined in three male and two female mice of a senescence-prone mouse strain (SAM P(8)) monthly for 12 months. These results were compared with those in age-matched mice of similar background but senescence resistant (SAM R(1)). Choroidal vascular casts were prepared at 12 months in seven mice each of the SAM P(8) and SAM R(1) strains. Quantitative analysis of area of choriocapillaris was performed by automated image analysis, and the results were analyzed by paired Student's t-test. RESULTS: We found in the SAM P(8) strain that hair loss, coarseness of hair texture, and ulceration of skin appeared and increased as the age advanced (at approximately 5-9 months). Eyecup examination showed no differences. Light and electron microscopy revealed progressively more prominent abnormalities in the RPE and Bruch's membrane mice older than 10 months. Two of the five SAM P(8) mice older than 11 months showed what appeared to be intra-Bruch's membrane choroidal neovascularization. The RPE and Bruch's membrane appeared normal in the SAM R(1) strain. In the SAM P(8), vascular casts of the choriocapillaris showed a mild but significant decrease in vascular area when compared with the SAM R(1) strain at 12 months (P = 0.011). CONCLUSIONS: Senescence accelerated mice develop progressive age-related changes in the RPE-Bruch's-choriocapillaris complex that have features that may be relevant in the study of age-related macular changes in humans.

Aging↗