Coproporphyrinogen oxidase, protoporphyrinogen oxidase and ferrochelatase activities in iron-overloaded and ethanol-treated rats

The activities of coproporphyrinogen oxidase, protoporphyrinogen oxidase and ferrochelatase in liver homogenates of iron-overloaded and acutely or chronically ethanol-treated rats were assayed by high performance liquid chromatographic methods. Decreased coproporphyrinogen oxidase activity was found in chronically carbonyliron-fed rats while the activities of protoporphyrinogen oxidase and ferrochelatase remained unchanged. Coproporphyrinogen oxidase and protoporphyrinogen oxidase activities in both chronically and acutely ethanol-treated animals were not significantly different from controls. In chronically ethanol-fed rats normal ferrochelatase activity was found.

The effects of ethanol and anticonvulsants on erythroid delta-aminolaevulinic acid synthase

The activity of delta-aminolaevulinic acid (ALA) synthase was measured in bone marrow from 13 control subjects, 12 chronic alcoholic patients and 9 patients on long term anticonvulsant therapy. The majority of patients in both groups had macrocytic red cells in the absence of megaloblastic changes in the marrow. There was a significant increase in ALA synthase activity in the alcoholic patients but no significant increase in enzyme activity in the patients on anticonvulsants and overall there was no correlation of activity with MCV. The macrocytosis associated with these drugs does not therefore appear to result from accelerated erythroid haem synthesis.

Bilateral multiple cystic kidney disease and renal cortical abscess in a Boerboel

Cystic renal disease is rare in dogs and although infected renal cysts have been reported in humans, no report could be found in dogs. A 58 kg, 5-year-old, castrated, male Boerboel presented with weight loss, pyrexia, lethargy and vomiting, 20 months after an incident of haematuria was reported. The initial ultrasonographic diagnosis was bilateral multiple renal cysts of unknown aetiology. The cysts had significantly increased in size over the 20-month period and some contained echogenic specks which could be related to infection, normal cellular debris or haemorrhage. In both kidneys the renal contours were distorted (the left more than the right). The abnormal shape of the left kidney was largely due to multiple cysts and a large crescent-shaped septate mass on the cranial pole of the kidney. Aspirates of the septate mass were performed (left kidney) and the cytology and culture were indicative of an abscess. It is suggested that the previous incident of haematuria provided a portal of entry for bacteria into the cysts resulting in renal cortical abscess formation.

Molecular typing of Neisseria gonorrhoeae by restriction fragment length polymorphisms

OBJECTIVE

To characterise Neisseria gonorrhoeae isolates by restriction fragment length polymorphisms (RFLPs) in ribosomal RNA genes.

DESIGN

Generation of RFLP patterns by HincII restriction of rRNA genes followed by hybridisation with a non-radioactive labelled broad spectrum 16 + 23S rRNA gene probe. This typing method was developed and compared with MAb based serotyping.

SPECIMENS

Forty three randomly collected isolates from Bangkok (27 isolates) and Singapore (16 isolates) were studied.

RESULTS

The RFLP patterns generated were reproducible and highly discriminatory between strains. Analysis of RFLPs produced by HincII restriction of rRNA genes established 9 patterns amongst the 43 isolates examined. Strains present within a common serovar could be further subdivided by RFLP typing. Identical RFLP patterns were found in some strains that belonged to various serovars.

CONCLUSION

RFLP typing based on heterogeneities of rRNA gene restriction patterns could be advantageously used to complement monoclonal antibody based serotyping for further subdivision of serovars. Higher sensitivity of this combined approach would enable better differentiation of strains in epidemiological studies.

Determination of hydroxy and peroxy acid derivatives of uroporphyrin in the plasma of patients with congenital erythropoietic porphyria by high-performance liquid chromatography

A reversed-phase high-performance liquid chromatographic method is described for the determination of hydroxy and peroxy acid derivatives of uroporphyrin in the plasma of patients with congenital erythropoietic porphyria. The porphyrins were extracted from the plasma with 20% trichloroacetic acid-dimethyl sulphoxide (1:1, v/v). The supernatant after centrifugation was chromatographed on a Hypersil-ODS column by gradient elution with 9% (v/v) acetonitrile in 1 M ammonium acetate buffer (pH 5.16) (solvent A) and 10% (v/v) acetonitrile in methanol (solvent B) as the gradient mixture. The method was also suitable for the preparative isolation of the porphyrins.

Comparison of HPLC, capillary electrophoretic and direct spectrofluorimetric methods for the determination of temoporfin-poly(ethylene glycol) conjugates in plasma

High-performance liquid chromatographic (HPLC), capillary electrophoretic (CE) and direct spectrofluorimetric methods for the determination of temoporfin-poly(ethylene glycol) 2000 conjugate (m-THPC-PEG 2000) in plasma are described and compared. m-THPC-PEG 2000 in plasma was quantitatively extracted (recovery 101-107%) with CH3OH-DMSO (4 + 1 v/v). The supernatant after centrifugation was used for HPLC, CE or direct spectrofluorimetric determination. The major drawback of the HPLC method was that it gave a broad and split peak even under gradient elution conditions, resulting in difficulty in detection and quantification. This is because m-THPC-PEG 2000 consists of a group of compounds with an average molecular mass of approximately 8680 Da owing to the wide molecular mass distribution of PEG 2000 used in the synthesis of the drug. m-THPC-PEG 2000 gave a single and relatively sharp peak when separated by CE with sodium tetraborate buffer (pH 9.45) in the presence of sodium dodecyl sulfate as the running buffer. However, this method lacks the necessary sensitivity for detecting the drug in plasma extract because of the limited sample volume that can be injected. Direct spectrofluorimetry is the method of choice because of its simplicity, specificity and sensitivity. Using an excitation wavelength of 423 nm and the specific emission maximum of 657 nm, the fluorescence intensity could be sensitively measured. The calibration curve constructed by plotting fluorescence intensity against concentration was linear within the range 1.32-1056 ng ml-1. The detection limit (S/N = 3) was 1.32 ng ml-1 and the limit of quantification (S/N = 10) was 2.24 ng ml-1. The precision and reproducibility were assessed by repeated analysis (n = 24) of spiked plasma samples at 350.8 and 699.3 ng ml-1. The RSD was 4.5% and 1.6%, respectively.

Efficacy of intracytoplasmic sperm injection (ICSI) treatment in the immunological infertile patients

PROBLEM

To evaluate the efficacy of intracytoplasmic sperm injection (ICSI) treatment in the immunological infertile patients.

METHODS

The subjects were 60 cycles of 44 immunological infertile patients and these clinical data were analysed, retrospectively. They were classified into female and male immunological infertility group and were treated with conventional IVF, ICSI, and half-ICSI.

RESULTS

The fertilization rate of ICSI (60.3%) and half-ICSI (60.7%) cycles were significantly (P < 0.01) higher than conventional IVF (42.6%) cycles. In the male immunological infertility group, fertilization rate was significantly (P < 0.01) higher in ICSI (60.7%) and half-ICSI (66.7%) cycles than in conventional IVF (27.4%) cycles and clinical pregnancy rate was higher in ICSI (54.5%) and half ICSI (33.3%) than in conventional IVF (25.0%) cycles.

CONCLUSIONS

We suggest that ICSI treatment is highly effective method to improve fertilization and pregnancy rate in IVF-ET program of male immunological infertility.

Pharmacokinetics of tetra(m-hydroxyphenyl)chlorin in human plasma and individualized light dosimetry in photodynamic therapy

The pharmacokinetics of the photosensitizer 5,10,15,20-tetra(m-hydroxyphenyl)chlorin (mTHPC) was investigated in the plasma of 20 patients by absorption and fluorescence spectroscopy. The temporal behavior was characterized by a rapid decrease in concentration during the first minutes after intravenous injection of 0.15 mg/kg mTHPC. A minimum concentration in the plasma was reached after about 45 min. The drug concentration then increased again, attaining a maximum after about 10 h, after which it decreased again with a halflife of about 30 h. Irradiation tests in the oral cavity at different time intervals after the injection revealed that the tissue reaction was only partially correlated with the mTHPC plasma level. The tissue response was stronger at later drug-light intervals (1-4 days) than during the first hours after injection even though the mTHPC plasma concentration was higher at the shorter times. Relative mTHPC concentrations were also measured in the mucosae of the oral cavity, the esophagus and the bronchi of 27 patients by light-induced fluorescence spectroscopy using an optical fiber-based spectrometer. These measurements were performed prior to photodynamic therapy (PDT), 4 days after injection of the photosensitizer. Highly significant linear correlations were found between the relative mTHPC concentrations in the mucosae of these three organs. Likewise, the plasma levels of mTHPC measured just before PDT were significantly correlated with the mTHPC concentrations in the three types of mucosae mentioned above. These results indicate that mTHPC plasma levels measured just before PDT can be used for PDT light dosimetry.

High performance liquid chromatographic studies of erythrocytes haem biosynthetic enzyme activities in alcoholic macrocytosis

The activities of 5-aminolaevulinate dehydrase (ALA-D), hydroxymethylbilane synthase (HMB-S), uroporphyrinogen III synthase (URO-S) and uroporphyrinogen decarboxylase (URO-D) in the erythrocytes of alcoholics were assayed and compared with those in controls and abstaining alcoholics. The HMB-S and URO-S activities in alcoholics were significantly higher than the controls and there were significant correlations between enzyme activities and mean corpuscular volume (MCV). Alcoholics abstaining from alcohol over a nine-month period showed a return to normal enzyme activities in parallel with the normalization of their MCV. Abstaining alcoholics thus all had normal HMB-S and URO-S activities. The ALA-D and URO-D activities of alcoholics were not significantly different from controls or from abstaining alcoholics. Alcohol appears to have a selective effect on the haem biosynthetic enzymes in the erythron.

Uptake and localisation of haematoporphyrin derivative in normal rat liver

Fluorescence microscopy and analytical subcellular fractionation were used to investigate the hepatic localisation of haematoporphyrin derivative (HPD) after intraperitoneal administration. HPD was found to rapidly accumulate in the liver and then to slowly decline over 48 hr. Fluorescence microscopy showed that although at early times porphyrins could not be localised to a particular cell type, at 24 hr porphyrins were preferentially localised to the Kupffer cells of the liver. Subcellular fractionation studies indicated that the initial rapid uptake of HPD was to the cytosol. However, at 24 hr, porphyrins appeared to be localised to lysosomes. Lysosomal localisation was confirmed using the selective organelle perturbant, Triton WR 1339. No evidence was found either at the light microscope level or by subcellular fractionation to suggest association of HPD with other organelles. HPLC analysis showed that the porphyrins present in the plasma and in the cytosol and lysosome fractions were mainly the (RS, SR) and (RR, SS) diastereoisomers of haematoporphyrin and the two position isomers 8-(1-hydroxyethyl)-3-vinyldeuteroporphyrin and 3-(1-hydroxyethyl)-8-vinyldeuteroporphyrin. There was no evidence for the involvement of dimers such as dihaematoporphyrin ether.

Adenine nucleotide concentrations in peripheral blood lymphocytes from patients with common variable hypogammaglobulinaemia and B-cell chronic lymphatic leukaemia

The adenine nucleotide profiles (AMP, ATP, NAD and NADH2) of peripheral blood lymphocytes isolated from patients with common variable hypogammaglobulinaemia (CVH) were similar to those in control cells. AMP and ATP levels were also similar in the lymphocytes of patients with chronic lymphatic leukaemia (CLL). Since CVH and CLL patients have reduced activity of plasma membrane ecto-5'-nucleotidase, our data suggests that this enzyme does not regulate the levels of intracellular adenine nucleotides, at least in "resting" cells.

Metabolic and drug profiling

Over recent years, advances in analytical technology have greatly improved our ability to study the metabolism of compounds from either endogenous or erogenous sources. The application of gas-liquid chromatography, mass spectrometry, high-performance liquid chromatography and immunological approaches are discussed in relation to the analysis of steroids, bile acids, organic acids, prostaglandins, porphyrins and bile pigments, amino acids, proteins, nucleotides, catecholamines, vitamins and drugs.

Characterization of metabolites of the chemopreventive agent curcumin in human and rat hepatocytes and in the rat in vivo, and evaluation of their ability to inhibit phorbol ester-induced prostaglandin E2 production

Curcumin, the yellow pigment in turmeric, has been shown to prevent malignancies in a variety of tissues in rodents, especially in the intestinal tract. Pharmacological activities of curcumin in cells in situ germane to chemoprevention, such as inhibition of expression of cyclooxygenase-2 (COX-2), require drug concentrations in the 10(-5) - 10(-4) M range. The systemic bioavailability of curcumin is low, so that its pharmacological activity may be mediated, in part, by curcumin metabolites. To investigate this possibility, we compared curcumin metabolism in human and rat hepatocytes in suspension with that in rats in vivo. Analysis by high-performance liquid chromatography with detection at 420 and 280 nm permitted characterization of metabolites with both intact diferoylmethane structure and increased saturation of the heptatrienone chain. Chromatographic inferences were corroborated by mass spectrometry. The major metabolites in suspensions of human or rat hepatocytes were identified as hexahydrocurcumin and hexahydrocurcuminol. In rats, in vivo, curcumin administered i.v. (40 mg/kg) disappeared from the plasma within 1 h of dosing. After p.o. administration (500 mg/kg), parent drug was present in plasma at levels near the detection limit. The major products of curcumin biotransformation identified in rat plasma were curcumin glucuronide and curcumin sulfate whereas hexahydrocurcumin, hexahydrocurcuminol, and hexahydrocurcumin glucuronide were present in small amounts. To test the hypothesis that curcumin metabolites resemble their progenitor in that they can inhibit COX-2 expression, curcumin and four of its metabolites at a concentration of 20 microM were compared in terms of their ability to inhibit phorbol ester-induced prostaglandin E2 (PGE2) production in human colonic epithelial cells. Curcumin reduced PGE2 levels to preinduction levels, whereas tetrahydrocurcumin, previously shown to be a murine metabolite of curcumin, hexahydrocurcumin, and curcumin sulfate, had only weak PGE2 inhibitory activity, and hexahydrocurcuminol was inactive. The results suggest that (a) the major products of curcumin biotransformation by hepatocytes occur only at low abundance in rat plasma after curcumin administration; and (b) metabolism of curcumin by reduction or conjugation generates species with reduced ability to inhibit COX-2 expression. Because the gastrointestinal tract seems to be exposed more prominently to unmetabolized curcumin than any other tissue, the results support the clinical evaluation of curcumin as a colorectal cancer chemopreventive agent.

Evidence that serine 304 is not a key ligand-binding residue in the active site of cytochrome P450 2D6

Homology models of cytochrome P450 2D6 (CYP2D6) have identified serine 304 as an active-site residue and implicated a putative role for this residue in substrate enantioselectivity and the differential inhibition of enzyme activity by the diastereoisomers quinine and quinidine. The role of serine 304 in selectivity is thought to be achieved through a preferential hydrogen-bond interaction between the hydroxyl group of the residue and one of the stereoisomers of each ligand. We have tested this hypothesis by substituting serine 304 with alanine, a non-hydrogen-bonding residue, and compared the properties of the wild-type and mutant enzymes in microsomes prepared from yeast cells expressing the appropriate cDNA-derived enzyme. The Ser(304)Ala substitution did not alter the enantioselective oxidation of metoprolol; the O-demethylation reaction remained R-(+)-enantioselective (wild-type, R/S, 1.7; mutant, R/S, 1.6), whereas alpha-hydroxylation remained S-(-)-enantioselective (wild-type and mutant, R/S, 0.7). Similarly, the selective oxidation of the R-(+) and S-(-) enantiomers of propranolol to the major 4-hydroxy metabolite was identical with both wild-type and mutant forms of the enzyme (R/S 0.9), although the formation of minor metabolites (5-hydroxy and deisopropylpropranolol) did show some slight alteration in enantioselectivity. The differential inhibition of enzyme activity by quinine and quinidine was also identical with both forms of CYP2D6, the IC(50) values for each enzyme being approx. 10 microM and 0.1 microM for quinine and quinidine, respectively. The kinetics of formation of alpha-hydroxymetoprolol and 4-hydroxydebrisoquine by wild-type and the Ser(304)Ala mutant was also very similar. However, modest changes in the regioselective oxidation of metoprolol and debrisoquine were observed with the Ser(304)Ala mutant. The regio- and enantioselective oxidation of an analogue of metoprolol, in which the hydroxyl group attached to the chiral carbon was replaced by a methyl moiety, was again identical with both wild-type and Ser(304)Ala mutant. However, the observed selectivity was the reverse of that observed with metoprolol. Collectively, these data indicate that Ser(304) is unlikely to be a key ligand-binding residue, although the residue may indeed be located in the active-site cavity. The reversal of selectivity with the methyl analogue of metoprolol indicates that the hydroxyl group attached to the chiral centre of ligands, such as metoprolol, is important in defining the enzyme's selective properties, and that a hydrogen-bonding residue, other than Ser(304), may be involved in this interaction. Current homology models of the active site of CYP2D6 that predict a hydrogen-bond interaction between Ser(304) and specific ligands will need to be re-evaluated, and other candidate residues capable of such an interaction nominated and tested by site-directed mutagenesis studies.

Cytotoxic activities of chemical constituents from Mesua daphnifolia

Detail chemical investigations on the stem bark of Mesua daphnifolia gave three triterpenoids and four xanthones. They are friedelin (1), friedelan-1,3-dione (2), lup-20(29)- en-3ss-ol (3), cudraxanthone G (4), ananixanthone (5), 1,3,5-trihydroxy-4-methoxyxanthone (6) and euxanthone (7). These chemical constituents were tested in vitro for their cytotoxic activities against four cell lines, MDA-MB-231 (human estrogen receptor negative breast cancer), HeLa (cervical carcinoma), CEM-SS (T-lymphoblastic leukemia) and CaOV3 (human ovarian cancer). Compound 4 showed a broad spectrum of activity against the MDA-MB-231, HeLa and CEM-SS cell lines with IC5 0 values of 1.3, 4.0 and 6.7 microg/ml respectively. Meanwhile, the other compounds 1, 2, 3, 5, 6 and 7 gave only selective activities against the cell lines.