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Biomedical subjects

H Koch

Publications and source records attributed to H Koch.

618 records · Page 35Linked to original sources
PubMedDate not supplied

Confirmatory method for sulfonamide residues in animal tissues by gas chromatography and pulsed positive ion-negative ion-chemical ionization mass spectrometry.

A confirmatory method has been developed for determination of 13 sulfonamides in edible tissues. The assay involves extraction from a solution resulting from a screening procedure by liquid chromatography and subsequent derivatization. Sulfachloropyridazine (SCP), sulfadiazine (SDA), sulfadimethoxine (SDM), sulfamethazine (SMZ), sulfamerazine (SME), sulfamethoxazole (SMX), sulfamethoxypyridazine (SMP), sulfapyridine (SPR), sulfaquinoxaline (SQX), and sulfathiazole (STA) were detected as the N1-methyl-N4-trifluoroacetyl derivatives, sulfaguanidine (SGU) as the same derivative after cyclization by hexafluoroacetylacetone, and sulfacetamide (SAC) as the methyl derivative. These sulfonamides were detected by gas chromatography and pulsed positive ion-negative ion-chemical ionization mass spectrometry with methane as the reactant gas, whereas sulfanilamide (SAA) was determined as the methyl derivative by electron-impact ionization.

Acylation↗
PubMedDate not supplied

Aminoterminal propeptide of type III procollagen: a marker of hepatic fibrosis after bile duct obstruction in the monkey.

BACKGROUND/AIMS: In an experimental study in monkeys, liver fibrosis development after segmental bile duct obstruction was investigated and correlated with the aminoterminal propeptide of type III procollagen (PIIINP). MATERIALS AND METHODS: Segmental bile duct obstruction was produced by ligation and section of the left hepatic bile duct in all monkeys. Fibrosis induction was examined by intravenous leukotriene C4 (LTC4, 5 nmol/kg) application, endogenous LT-production stimulated by endotoxin (LPS,salmonella abortus equi, 50 ng/kg), fibrosis inhibition by dexamethasone (1 mg/kg) intramuscularly and subsequent endogenous LT-production stimulation by LPS (50 ng/kg). Ligated and unligated liver lobe biopsies were taken 3, 7 and 12 weeks after ligation. All portal areas were measured morphometrically. PIIINP was measured by a specific radioimmunoassay each week and correlated with the morphometric results. RESULTS: Bile duct obstruction leads to secondary sclerosing cholangitis with bile duct vanishing and subsequent biliary cirrhosis combined with perivenous sclerosis and cavernous transformation of the terminal vein. The collagen concentration increased in the nonligated lobe from mean +/-SEM 1.05 +/- 0.03% to 1.53 +/- 0.19% only after LTC4 and with no difference in the other groups. In the ligated lobe collagen concentration increased significantly in all groups continuously from 1.05 +/- 0.03% up to: controls 6.1 +/- 0.9%, dexamethasone 5.9 +/- 0.8%, LPS 8.2 +/- 0.8%, LTC4 9.075 +/- 1.4%. PIIINP concentration rose within 6 weeks in the controls with hepatic bile duct obstruction from 34.43 +/- 15 ng/ml up to 57 +/- 13.27 ng/ml, after dexamethasone to 48.5 +/- 18.23 ng/ml, after LPS to 57 +/- 13.27 ng/ml, after LTC4 to 80.25 +/- 16.04 ng/ml. After 12 weeks, PIIINP decreased in the controls resp. after dexamethasone to 41.25 +/- 6.94 ng/ml resp. 33.5 +/- 7.72 ng/ml and increased after LPS resp. LTC4 up to 64.25 +/- 17.07 ng/ml resp.104 +/- 22.46 ng/ ml. The correlation of collagen deposition and PIIINP was in the controls r = 0.83, after dexamethasone r = 0.71, after LPS r = 0.83 after LTC4 r = 0.91. CONCLUSION: PIIINP determination after segmental bile duct obstruction correlates with collagen deposition and allows evaluation of hepatic fibrosis activity.

Animals↗