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Biomedical subjects

P Joseph

Publications and source records attributed to P Joseph.

At least 73 records · Page 4Linked to original sources
PubMed1988

Response of blood and brain cholinesterase to dermal exposure of bromophos in the rat.

Response of cholinesterase to dermal exposure of acute, single and multiple doses of Bromophos in the female rat has been studied. Dose-response studies (50-4000 mg/kg body weight, 24 h exposure) showed that plasma cholinesterase was most sensitive to inhibition in vivo, followed by the brain and erythrocyte acetylcholinesterase. The ID50 values for the in vivo cholinesterase inhibition were 10.1, 576.1 and 1938.0 mg/kg body weight for the plasma, brain and erythrocytes, respectively. In time-course studies after a single sublethal dose of 1000 mg/kg body weight (24 h) of Bromophos, the serum and brain cholinesterase were rapidly inhibited reaching a maximum at 16 h. Recovery was complete in the case of serum at 14 days post-exposure, whereas the brain enzyme was not fully recovered at 21 days. In a subacute study, daily dermal application of 50 mg/kg body weight of Bromophos for 5 and 10 days, resulted in high inhibition of the serum cholinesterase and brain acetylcholinesterase, the former being more marked which was reversible after 10 or 15 days of post-exposure period. Very low levels of dermal exposure of Bromophos (10-50 mg/kg body weight) for 17 days caused pronounced depression of serum cholinesterase which completely recovered in 15 days after cessation of exposure suggesting that the serum cholinesterase could serve as the most sensitive diagnostic indicator of Bromophos exposure.

Animals↗
PubMed1986

Cerebral consequences of cardiopulmonary bypass.

55 patients undergoing coronary-artery bypass surgery (CABS) and a comparison group of 20 patients having thoracic or major vascular surgery were investigated preoperatively and 8 days and 8 weeks postoperatively for changes in neuropsychological status, psychiatric state, cerebral blood flow, and neurological signs, this last being assessed also at 24 h. Major persisting neurological changes were rare, but minor abnormalities were significantly more common after CABS than after thoracic or vascular surgery. Neuropsychological deficits were common at 8 days in both CABS and comparison groups, and in about a third of all patients persisted at 8 weeks. Cerebral blood flow was reduced at 8 days in some CABS patients, but this was not significant for the group. Pre-existing cerebrovascular disease was not predictive, but low perfusion pressure and long bypass time were associated with postoperative deficits.

Adult↗
PubMed1985

Temporomandibular joint: magnetic resonance imaging.

Magnetic resonance (MR) imaging of the temporomandibular joint was performed in two subjects using a 1.5 T experimental imaging system equipped with a 6.5 cm surface coil antenna. Normal and pathologic anatomy were demonstrated with exquisite detail. Anterior displacement of the joint meniscus was clearly visible in the symptomatic subject, consistent with arthrographic confirmation.

Adult↗
PubMed1985

Contrast enhancement of spontaneous animal CNS tumors with gadolinium DTPA: a correlation of MRI with x-ray CT.

A visual comparison was made between both pre-contrast and post-contrast x-ray computerized tomographic images (X-CT) and magnetic resonance tomographic images (MRI) of spontaneous CNS tumors in three animals. The contrast agents, HypaqueR-76 (X-CT) and Gadolinium DTPA (MRI), were administered as an intravenous bolus injection. The parameters for comparison of pre- and post-contrast features included: lesion discrimination, demarcation, and intensity and pattern of enhancement. Necropsy specimens were included to correlate the anatomic fidelity of scan appearances for each modality and to establish a final diagnosis. There was good visual correlation of the lesion site with both X-CT and MRI. The intensity of lesion enhancement with the contrast reagents was similar for each modality but there were subtle differences in the pattern of enhancement. Overall, MRI in conjunction with the contrast agent Gadolinium DTPA, was as good or better at delineating the presence and extent of CNS tumors than contrast enhanced X-CT. Contrast agents may be necessary to provide increased lesion detectability and delineation when imaging with magnetic resonance.

Adenoma↗
PubMed1984

Magnetic resonance imaging of postoperative patients with metallic implants.

Magnetic resonance imaging (MRI) examinations were reviewed in 10 postsurgical patients with metallic implants in the abdomen or pelvis. MRI scans in these patients were free of the streak artifacts commonly encountered in computed tomography. This represents a significant advantage in diagnostic imaging in postsurgical patients, and it suggests that MRI may be a valuable technique in the postoperative assessment of patients with extensive abdominal surgical clips or metallic prostheses.

Adolescent↗
PubMed1980

Gentamicin-resistant Serratia marcescens endophthalmitis.

In a case of metastatic Gram-negative endophthalmitis caused by Serratia marcescens, the bacterial isolate was resistant to gentamicin sulfate and tobramycin but sensitive to amikacin sulfate, a new semisynthetic aminoglycoside approved for systemic use. The importance of antibiotic-resistant S marcescens as a systemic and ocular pathogen is reviewed.

Amikacin↗
PubMed1980

Atrial myxoma infected with Candida: first survival.

We report the first case of an atrial myxoma infected with the fungus, Candida tropicalis. We believe that this is the only patient with an atrial myxoma, infected with any species of Candida, who has demonstrated long-term survival. A review of the world's literature of infected myxomas is presented.

Adult↗
PubMedDate not supplied

Relentless progression of venous obstruction in a case of Budd-Chiari syndrome related to heterozygous protein C deficiency.

A 28-year-old man with heterozygous protein C deficiency presented with Budd-Chiari syndrome resulting from hepatic vein obstruction. Over the next 40 months, standard oral anticoagulant therapy and multiple percutaneous interventions aimed at relieving hepatic vein obstruction could not prevent progression of the disease ultimately to cirrhosis and death. Serial angiography provided unique documentation of the relentless progression of hepatic venous obstruction, which was related to the disease and to iatrogenic factors. Operative findings obtained during unsuccessful mesocaval shunt surgery revealed that venous disease in protein C deficiency can be far more extensive than is clinically anticipated. The ineffectiveness of therapy in this patient may be related to standard oral anticoagulant therapy being insufficient to offset the risk of recurrent thrombosis and progression to an advanced stage of vascular damage.

Adult↗
PubMedDate not supplied

Peroxidase: a novel pathway for chemical oxidation in human term placenta.

Hydrogen peroxide-dependent oxidation of xenobiotics in a crude fraction of human term placental membranes (nuclei, mitochondria and microsomes) was investigated. Guaiacol was employed as a model substrate. The rate of its oxidation was found to be dependent on the concentration of protein, H2O2 and the substrate as well as the pH of the buffer. Several other classical substrates for peroxidases from different sources viz. pyrogallol, benzidine, p-PDA, DMBD, ABTS, TMPD and TMBD and endogenous chemicals such as bilirubin and epinephrine were also found to undergo oxidation. The xenobiotic oxidizing capacity of the membranes was retained by CaCl2 (0.5 M) extract as well as by the partially purified enzyme obtained by affinity (Con A) chromatography. The H2O2-dependent chemical oxidation by the partially purified peroxidase was inhibited by NaN3 and KCN (IC50 values 41 and 23 microM respectively). These results suggest that peroxidase may be a major enzyme in human term placenta capable of oxidation of endogenous chemicals and xenobiotics.

Bilirubin↗
PubMedDate not supplied

Bioactivation of benzo(a)pyrene-7,8-dihydrodiol catalyzed by lipoxygenase purified from human term placenta and conceptal tissues.

Bioactivation of 14C-benzo(a)pyrene-7,8-dihydrodiol catalyzed by lipoxygenase purified from human term placenta of nonsmoking women and intrauterine conceptal tissues (at 4 weeks of gestation) was investigated. Incubation of 14C-benzo(a)pyrene-7,8-dihydrodiol with 3 mM linoleic acid in the presence of lipoxygenase purified from either human term placenta or intrauterine conceptal tissues resulted in co-oxidation generating several soluble and protein-bound metabolites of benzo(a)pyrene-7,8-dihydrodiol. The co-oxidation was inhibited significantly by the specific lipoxygenase inhibitor, nordihydroguaiaretic acid. Substitution for the active enzyme in the reaction mixture with heat denatured enzyme resulted in almost complete abolition of benzo(a)pyrene-7,8-dihydrodiol co-oxidation. These results suggest that lipoxygenase in the placentas and intrauterine conceptal tissues is capable of metabolizing benzo(a)pyrene-7,8-dihydrodiol to several reactive metabolites and may represent one of the major xenobiotic metabolizing pathways of bioactivating chemicals in the intrauterine compartment.

Biotransformation↗
PubMedDate not supplied

Placental peroxidase--further purification of the enzyme and oxidation of thiobenzamide.

Human term placental peroxidase [donor: hydrogen peroxide (H2O2) oxidoreductase] from non-smoking women was purified by extraction of the membrane fraction with 0.5 M Ca2+ followed by affinity chromatography on concanavalin A, hydrophobic chromatography on phenyl sepharose CL-4B and gel filtration chromatography on sephacryl S-200 columns. The final enzyme preparation was 110-fold pure when compared to the Ca2+ extract and the overall recovery of the procedure was 55 per cent. SDS-PAGE of the final product showed the presence of four protein staining bands of molecular weights 30, 32.5, 35 and 55 KDa. The purified peroxidase eluted as a single peak from the sephacryl S-200 column suggesting apparent homogeneity of the protein. The purified placental peroxidase oxidized thiobenzamide to its sulfoxide. The highest rate of TB S-oxidation under optimum conditions was 18 +/- 2.15 mumoles/min/mg protein. The H2O2-dependent thiobenzamide S-oxidation catalysed by the placental peroxidase was inhibited by KCN and NaN3 with IC50 values of 16.9 and 34 microM respectively.

Chromatography, Affinity↗