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Biomedical subjects

S Patel

Publications and source records attributed to S Patel.

At least 829 records · Page 46Linked to original sources
PubMedDate not supplied

Anticonvulsant activity of the NMDA antagonists, D(-)4-(3-phosphonopropyl) piperazine-2-carboxylic acid (D-CPP) and D(-)(E)-4-(3-phosphonoprop-2-enyl) piperazine-2-carboxylic acid (D-CPPene) in a rodent and a primate model of reflex epilepsy.

D-(-)4-(3-phosphonopropyl)piperazine-2-carboxylic acid (D-CPP) and its unsaturated analogue (D(-)(E)-4-(3-phosphonoprop-2-enyl) piperazine-2-carboxylic acid (D-CPPene) have been administered to DBA/2 mice (intracerebroventricularly, i.c.v., intraperitoneally, i.p., and orally, p.o.) and to photosensitive baboons, Papio papio (intravenously, i.v., and orally), and their effects on reflexly induced epileptic responses assessed. In DBA/2 mice the clonic phase of the seizure response to sound is suppressed by D-CPP with an ED50 of 5.5 micrograms/mouse, i.c.v.; 0.69 mg (2.75 mumol)/kg i.p. and 16.6 mg (65.8 mumol)/kg p.o. compared with, for D-CPPene, 2.2 micrograms/mouse i.c.v., 0.41 mg (1.54 mumol)/kg i.p. and 10.8 mg (40.2 mumol)/kg, p.o. In Papio papio myoclonic responses to stroboscopic stimulation are suppressed 24 and 48 h after D-CPP 32 mg (127 mumol)/kg p.o. Administration of D-CPPene 8-16 mg (30-60 mumol)/kg i.v. produces protection against myoclonic responses after 1-2 h, lasting for 48 h. Oral administration of D-CPPene 32-64 mg (119-239 mumol)/kg produces protection beginning after 4 h and sustained for 48 h. Measurements of plasma D-CPPene concentration show rapid clearance after i.v. injection and a low plasma concentration 1.5-5 h after oral administration. The prolonged anticonvulsant action of D-CPP and D-CPPene following oral administration suggests that these compounds merit evaluation as antiepileptic therapy in man.

Acoustic Stimulation↗
PubMedDate not supplied

Understanding and management of amniotic fluid embolism.

Amniotic fluid embolism (AFE) is a rare obstetric problem characterized by sudden onset of hypotension, hypoxemia, and coagulopathy. This case represents the difficulty in differentiating AFE from other etiologies of cardiopulmonary compromise. The definitive diagnosis of AFE is made at autopsy with the demonstration of fetal cell elements in the pulmonary vasculature. Diagnosis can be highly suspected if squamous cells and other debris of presumed fetal origin are demonstrated in blood aspirated from the central venous or pulmonary artery circulation of symptomatic parturients. Predisposing factors for AFE include advanced maternal age, multiparity, large fetal size, and short tumultuous labor, especially if uterine stimulants are used. Cardiopulmonary resuscitation is the key to the treatment of parturients with AFE. A pulmonary artery catheter can be helpful in diagnosis and hemodynamic management of parturients with AFE.

Adult↗
PubMedDate not supplied

Autonomic effects on R-R variations of the heart rate in the squirrel monkey: an indicator of autonomic imbalance in conflict sickness.

To assess the contribution of the autonomic nervous system (ANS) to beat-to-beat (R-R interval) variations in the squirrel monkey, heart rate was analyzed after atropine, propranolol, carbachol, or isoproterenol administration, using a computer analyzing system. Heart rate variations were expressed as coefficient of variance (CV) of mean R-R interval. CV of R-R interval clearly was reduced by atropine but not by propranolol, indicating that the effect could be mediated through the parasympathetic nerve. CV of R-R interval was measured also under vestibulo-visual conflict (VVC) situation in pitch. Although CV of R-R interval increased during VVC, this variation almost was abolished after atropine administration. Monkeys with unilateral labyrinthectomy showed smaller variations than those without operation during exposure to VVC. CV of R-R interval is a useful parameter for the objective and quantitative evaluation of ANS function and may be a good indicator to demonstrate the severity of motion sickness without invasive methods.

Animals↗
PubMedDate not supplied

A revisit of MRI analysis for synovial sarcoma.

We evaluated magnetic resonance imaging (MRI) findings of synovial sarcomas in 22 patients, and the most common MRI findings were oval and well-defined nodular masses with heterogeneous intermediate signal intensity (SI) on T1 weighted images (WI), high SI on T2-WI and heterogeneous contrast enhancement. A cystic component was seen in 77%, intratumoral hemorrhage in 73%, and calcification in three monophasic sarcomas. Metastases were noted in lung (mostly biphasic type), lymph node, and bone. Posttreatment changes revealed diffusely increased S1 on T2-W1 and slightly diffuse contrast enhancement with feathery appearance. Morphology and MR signal characteristics assist in synovial sarcoma management.

Adolescent↗
PubMedDate not supplied

Water-suppression MRI: role in the evaluation of osseous lesions.

The efficacy of chemical shift based water-suppression MRI in the evaluation of bone marrow lesions has not been previously reported. T1-weighted images without and with water suppression were compared in five patients with 16 lesions. There was a significant improvement in the contrast-to-noise ratio (from 4.32 to 5.95, P < 0.01) and contrast ratio (from 1.71 to 5.69, P < 0.004) with water suppression. Water suppression may be useful clinically by increasing the conspicuity of bone marrow lesions.

Adult↗
PubMedDate not supplied

Emergency percutaneous nephrostomy: results and complications.

PURPOSE: Percutaneous nephrostomy is a well-established standardized procedure in the management of patients with various urologic problems. The goal of this study was to evaluate the effectiveness and safety of percutaneous nephrostomy in an emergency setting. PATIENTS AND METHODS: Emergency percutaneous nephrostomy was performed in 160 patients with ages ranging from 2 to 89 years (mean, 52 years). Access to the kidney was planned and achieved with C-arm fluoroscopic guidance. RESULTS: The initial technical success rate was 98%. Overall complication rate was 34%; 6% were major and 28% were minor. Major procedure-related complications, including sepsis, occurred in 6% of patients. Hematuria requiring transfusion was noted in 2.4% of patients. Minor complications included catheter displacement or malposition (4.8%), pelvic perforation (4.3%), paralytic ileus (2.4%), pneumonia/atelectasis (1.8%), and pleural effusion (1.2%). High-risk patients included those with diabetes, hypertension, and obesity. No deaths or significant morbidity resulted from any complication. CONCLUSIONS: Emergency percutaneous nephrostomy under fluoroscopic guidance is a simple, safe, and effective procedure and should be offered in all suitably equipped radiology departments.

Adolescent↗
PubMedDate not supplied

Synthesis of a new fluoro-Wang resin for solid-phase reaction monitoring by 19F NMR spectroscopy.

A new fluoro-Wang resin is presented which facilitates solid-phase reaction monitoring using 19F NMR. The resin is easily synthesized and amenable to scale-up. The method described herein compliments single-bead FT-IR and 13C NMR techniques. This method allows monitoring of solid-phase reactions even if the resin bound intermediate is unstable to the cleavage conditions. In addition, this is a useful tool to study reaction kinetics on the solid phase.

Journal Article↗
PubMedDate not supplied

Iterated reaction graphs: simulating complex Maillard reaction pathways.

This study investigates a new method of simulating a complex chemical system including feedback loops and parallel reactions. The practical purpose of this approach is to model the actual reactions that take place in the Maillard process, a set of food browning reactions, in sufficient detail to be able to predict the volatile composition of the Maillard products. The developed framework, called iterated reaction graphs, consists of two main elements: a soup of molecules and a reaction base of Maillard reactions. An iterative process loops through the reaction base, taking reactants from and feeding products back to the soup. This produces a reaction graph, with molecules as nodes and reactions as arcs. The iterated reaction graph is updated and validated by comparing output with the main products found by classical gas-chromatographic/mass spectrometric analysis. To ensure a realistic output and convergence to desired volatiles only, the approach contains a number of novel elements: rate kinetics are treated as reaction probabilities; only a subset of the true chemistry is modeled; and the reactions are blocked into groups.

Aldehydes↗
PubMedDate not supplied

Urinary excretion and DNA binding of coal tar components in B6C3F1 mice following ingestion.

Urinary excretion of polycyclic aromatic hydrocarbon (PAH) metabolites and DNA binding of coal tar components in male mice were investigated following the ingestion of a coal tar adulterated diet. Male B6C3F1 mice were able to tolerate an F0927 basal gel diet which contained from 0.1 to 1% coal tar (tar weight/dry food weight) for 15 days. Mice maintained on a 0.1 and 0.2% coal tar diet had body weight gains similar to those of control animals. However, mice maintained on the 0.5 and 1.0% diet had body weight gains considerably lower than control values. Chemical-DNA adduct formation was detected and quantified in lung and forestomach tissue of animals on 0.1, 0.2, 0.5, and 1% coal tar containing diets. A dose-related effect was observed in lung DNA adduct formation while no dose effect was observed in forestomach tissue. In addition, overall adduct levels in lung tissue were considerably higher than forestomach levels for animals on the 0.5 or 1% diet. In contrast, DNA adduct levels were highest in the forestomach of animals on diets lower in coal tar content (0.1 or 0.2%). Chemical-DNA adducts of coal tar components were also evaluated for four other coal tar samples which varied in chemical composition. Mice were maintained on diets containing 0.25% of each coal tar for 15 days. Chemical-DNA adducts were detected in lung, liver, and spleen for all animals receiving these coal tar diets. DNA adduct patterns were similar while quantitative differences were observed between coal tar samples and tissue sites. Highest adduct levels were detected in lung DNA. Benzo[a]pyrene content in coal tar samples could not account for the DNA adduct levels observed with coal tar ingestion. The urinary excretion of select PAH metabolites following coal tar ingestion was evaluated by using urine collected on days 1 and 14 of diet administration. The levels of 1-hydroxypyrene in urine, the major PAH metabolite detected, correlated with the pyrene content of these coal tars. These data demonstrate that coal tar components are readily bioavailable following ingestion.

Animals↗
PubMedDate not supplied

Red cell phenotyping using hexadimethrine bromide (Polybrene) in a microplate system.

To provide rapidly phenotyped units of blood, we adapted the hexadimethrine bromide (Polybrene) technique to microplate technology. Pilot samples from 282 donor units were phenotyped for antigens in the Rh, Kidd, Kell, Duffy, and Ss systems with a standard tube-testing method and a Polybrene-microplate (P-MP) technique. Diluted antisera and a 1 percent red cell suspension were used to give P-MP reactions that were accurate and easy to interpret. One microplate, containing 96 tests, was prepared and read within 15 minutes for P-MP tests yielding direct agglutination (Rh, Jkb, Fya, Fyb), or within 19 minutes for P-MP tests requiring an antiglobulin phase (Jka, K, S, s). No false-positive results were found. No false-negative reactions were found in typing for Rh, K, S, s, or Jka antigens. Phenotyping for Jkb and Duffy antigens gave a false-negative rate of less than 0.015. Considerable savings in reagents were obtained through microplate miniaturization and through the enhancement of apparent antibody avidity in the Polybrene/low ionic medium which permitted dilution of reagent antisera. The P-MP technique affords a rapid, accurate, simple, and inexpensive means of phenotyping large numbers of donor units.

Blood Group Antigens↗
PubMedDate not supplied

Effective leukocyte removal from platelet preparations by centrifugation in a new pooling bag.

A pooling bag (Leukotrap, Cutter Laboratories, Berkeley, CA) with a protruding pocket at the bottom into which heavier cellular elements are collected after centrifugation at 390 X g for 10 minutes, was studied. The tab is clamped before transfusion. Varying numbers of platelet concentrates (PC) that had been stored for different durations were pooled and centrifuged in the bags. When 4 or more units of PC were studied, the results were independent of the number of units and the duration of storage. Approximately 90 percent of the contaminating leukocytes (WBC) were removed with a platelet loss of less than 10 percent. Similar results were obtained with single-donor platelets (WBCs decreased 93%; range, 77-99%; n = 12). Posttransfusion increments were similar to those with unmodified platelets; in four patients, febrile platelet transfusion reactions were eliminated by the WBC removal. Thus, the bags represent a simple, reproducible, and effective means of reducing WBC and red cell contamination of platelet preparations with acceptable platelet losses.

Blood Platelets↗
PubMedDate not supplied

Deoxynivalenol in wheat and maize flour reference materials. 2. Preparation and certification.

The preparation of four cereal reference materials (two wheat and two maize) and the certification of their 4-deoxynivalenol (DON) contents is described. The materials were prepared and certified within the BCR programme of the Commission of the European Community as part of a broad activity to improve accuracy and agreement of measurements of importance in food and agriculture. Reference material RM 379 was prepared from naturally contaminated wheat four blended with 'blank' material to achieve the desired DON content. The reference material RM 378 was prepared from naturally contaminated maize identified as containing approximately the desired DON content. Details are given of the milling, blending and packaging procedure, and the checks to ensure homogeneity and stability of the materials. The reference materials RM 396 and 377 were similarly prepared from the blank wheat and maize samples respectively. The certification exercise was carried out by five laboratories (with a further two to three laboratories providing supporting data) using a variety of extraction and clean-up procedures with either high performance liquid chromatography (HPLC) or gas chromatography (GC) as the determinative stages. Wheat RM 379 was certified as containing DON at a level of 673 +/- 21 micrograms/kg and wheat RM 396 as containing less than 50 micrograms/kg. Maize RM 378 was certified as containing DON at 425 +/- 38 micrograms/kg and maize RM 377 as containing less than 50 micrograms/kg. The materials are intended for the verification of methods used to determine DON in cereal samples.

Certification↗
PubMedDate not supplied

The development of five animal feed reference materials, certified for their aflatoxin B1 content.

The development of three peanut meal and two compound feed reference materials and the certification of their aflatoxin B1 content is described. The materials were prepared and certified within the Measurements and Testing Programme of the Commission of the European Communities as part of a broad activity to improve accuracy and agreement of results of measurements on food and agriculture. RM 262 (peanut meal) was prepared from uncontaminated peanut products. RM 263 and RM 264 (peanut meals) were prepared from naturally contaminated peanuts which were blended with uncontaminated ones, to achieve the desired aflatoxin B1 mass fractions. RM 375 and RM 376 (compound feeds) were made by blending decontaminated dairy feed together with commercial feed ration and contaminated dairy feed with several feed compounds, respectively. Details are given of the preparation and the investigations to verify homogeneity and stability of the materials. The certification exercise was carried out by 17 laboratories using a variety of extraction and clean-up procedures. Most laboratories used liquid chromatography as the determinative step, although operating under a variety of chromatographic conditions. A few laboratories applied thin layer chromatography with densitometric quantification. Peanut meal RM 262 was certified as containing aflatoxin B1 at a mass fraction of < 3 micrograms/kg, RM 263 at 43.3 +/- 2.1 micrograms/kg and RM 264 at 204 +/- 10 micrograms/kg. Compound feed RM 375 was certified as containing aflatoxin B1 at a mass fraction of < 1 micrograms/kg and RM 376 at 9.2 +/- 0.5 micrograms/kg. The materials can be employed either to establish or confirm a calibration curve, or to check the performance of a method.

Aflatoxin B1↗