Notizen: Electroreduction of Organic Compounds, XVIII / Electrochemical Dehalogenation of Chlorinated Dibenzofurans and Dibenzo-p-dioxins in Methanol

Mono and polyhalogenated dibenzofurans and dibenzo-p-dioxins are electrochemically reduced in a divided cell in technical methanol at a lead cathode.

Degradation of Chlorinated Dibenzofurans and Dibenzo-p-Dioxins by Sphingomonas sp. Strain RW1

The ability of the dibenzofuran- and dibenzo-p-dioxin-mineralizing bacterium Sphingomonas sp. strain RW1 (R.-M. Wittich, H. Wilkes, V. Sinnwell, W. Francke, and P. Fortnagel, Appl. Environ. Microbiol. 58:1005-1010, 1992) to oxidize chlorinated derivatives of dibenzofuran and dibenzo-p-dioxin was analyzed. Strain RW1 degraded several mono- and dichlorinated dibenzofurans and dibenzo-p-dioxins, but it did not degrade more highly chlorinated congeners. Most mono- and dichlorinated dibenzofurans and dibenzo-p-dioxins investigated in this study were degraded to the corresponding mono- and dichlorinated salicylates and catechols, respectively, together with salicylate and catechol. This indicates an initial dioxygenolytic attack on the substituted as well as on the nonsubstituted aromatic nucleus of most of the target compounds. Strain RW1 could not grow at the expense of monochlorinated dibenzo-p-dioxins and dibenzofurans as carbon sources, with the exception of 4-chlorodibenzofuran, which was stoichiometrically converted to 3-chlorosalicylate.

Routine versus clinically driven laboratory monitoring of HIV antiretroviral therapy in Africa (DART): a randomised non-inferiority trial

BACKGROUND

HIV antiretroviral therapy (ART) is often managed without routine laboratory monitoring in Africa; however, the effect of this approach is unknown. This trial investigated whether routine toxicity and efficacy monitoring of HIV-infected patients receiving ART had an important long-term effect on clinical outcomes in Africa.

METHODS

In this open, non-inferiority trial in three centres in Uganda and one in Zimbabwe, 3321 symptomatic, ART-naive, HIV-infected adults with CD4 counts less than 200 cells per microL starting ART were randomly assigned to laboratory and clinical monitoring (LCM; n=1659) or clinically driven monitoring (CDM; n=1662) by a computer-generated list. Haematology, biochemistry, and CD4-cell counts were done every 12 weeks. In the LCM group, results were available to clinicians; in the CDM group, results (apart from CD4-cell count) could be requested if clinically indicated and grade 4 toxicities were available. Participants switched to second-line ART after new or recurrent WHO stage 4 events in both groups, or CD4 count less than 100 cells per microL (LCM only). Co-primary endpoints were new WHO stage 4 HIV events or death, and serious adverse events. Non-inferiority was defined as the upper 95% confidence limit for the hazard ratio (HR) for new WHO stage 4 events or death being no greater than 1.18. Analyses were by intention to treat. This study is registered, number ISRCTN13968779.

FINDINGS

Two participants assigned to CDM and three to LCM were excluded from analyses. 5-year survival was 87% (95% CI 85-88) in the CDM group and 90% (88-91) in the LCM group, and 122 (7%) and 112 (7%) participants, respectively, were lost to follow-up over median 4.9 years' follow-up. 459 (28%) participants receiving CDM versus 356 (21%) LCM had a new WHO stage 4 event or died (6.94 [95% CI 6.33-7.60] vs 5.24 [4.72-5.81] per 100 person-years; absolute difference 1.70 per 100 person-years [0.87-2.54]; HR 1.31 [1.14-1.51]; p=0.0001). Differences in disease progression occurred from the third year on ART, whereas higher rates of switch to second-line treatment occurred in LCM from the second year. 283 (17%) participants receiving CDM versus 260 (16%) LCM had a new serious adverse event (HR 1.12 [0.94-1.32]; p=0.19), with anaemia the most common (76 vs 61 cases).

INTERPRETATION

ART can be delivered safely without routine laboratory monitoring for toxic effects, but differences in disease progression suggest a role for monitoring of CD4-cell count from the second year of ART to guide the switch to second-line treatment.

FUNDING

UK Medical Research Council, the UK Department for International Development, the Rockefeller Foundation, GlaxoSmithKline, Gilead Sciences, Boehringer-Ingelheim, and Abbott Laboratories.

Decision-making about hormone replacement therapy by women in England and Scotland

OBJECTIVE

The aim of this study was to explore women's decision-making about the balance of risks and benefits of taking hormone replacement therapy (HRT) based on the latest evidence from the Women's Health Initiative (WHI) trial of combined HRT.

METHODS

Women aged 50-69 years, who were eligible for the Women's International Study of long Duration Oestrogen after Menopause (WISDOM) trial, were invited to participate in one of eight focus groups. Participants were asked to discuss their views about taking HRT based on the latest international evidence.

RESULTS AND CONCLUSIONS

Eighty-two women participated overall. Qualitative content analysis was applied to the discussion transcripts. Women regarded the decisions they make about taking HRT as highly personal, and, for women currently taking HRT, the overwhelming reason for continuation was perceived improvement in quality of life regardless of either the risks or the benefits in the longer term.

Anaerobic initial reaction of n-alkanes in a denitrifying bacterium: evidence for (1-methylpentyl)succinate as initial product and for involvement of an organic radical in n-hexane metabolism

A novel type of denitrifying bacterium (strain HxN1) with the capacity to oxidize n-alkanes anaerobically with nitrate as the electron acceptor to CO(2) formed (1-methylpentyl)succinate (MPS) during growth on n-hexane as the only organic substrate under strict exclusion of air. Identification of MPS by gas chromatography-mass spectrometry was based on comparison with a synthetic standard. MPS was not formed during anaerobic growth on n-hexanoate. Anaerobic growth with [1-(13)C]n-hexane or d(14)-n-hexane led to a 1-methylpentyl side chain in MPS with one (13)C atom or 13 deuterium atoms, respectively. This indicates that the 1-methylpentyl side chain originates directly from n-hexane. Electron paramagnetic resonance spectroscopy revealed the presence of an organic radical in n-hexane-grown cells but not in n-hexanoate-grown cells. Results point at a mechanistic similarity between the anaerobic initial reaction of n-hexane and that of toluene, even though n-hexane is much less reactive; the described initial reaction of toluene in anaerobic bacteria is an addition to fumarate via a radical mechanism yielding benzylsuccinate. We conclude that n-hexane is activated at its second carbon atom by a radical reaction and presumably added to fumarate as a cosubstrate, yielding MPS as the first stable product. When 2,3-d(2)-fumarate was added to cultures growing on unlabeled n-hexane, 3-d(1)-MPS rather than 2,3-d(2)-MPS was detected, indicating loss of one deuterium atom by an as yet unknown mechanism.

A prospective study of faecal bile acids and colorectal cancer

A prospective study of 7079 people aged 45-74 recruited through general practices in South Wales, Herefordshire and Edinburgh, Scotland was undertaken to test the hypothesis that faecal bile acids are implicated in the causation of large bowel cancer. The population was recruited between 1974 and 1980 and the response rate for stool collection was 67%. Bile acid analyses were performed on those cases that presented by 1990. It was decided in advance to examine the hypothesis separately for left- and right-sided bowel cancer because of known epidemiological differences between the two sites and to exclude the cases presenting within 2 years of the stool sample from the analyses because the cancer could have been present at recruitment and might have possibly affected faecal bile acid concentrations. Each case (n = 51 left-sided and 8 right-sided) was matched with three controls by age (within 5 years), sex, place of residence and time of providing the stool sample (within 3 months). Statistical analyses using conditional logistic regression showed no significant differences between the left-sided cases and controls for any of the concentrations of individual bile acids, total bile acid concentrations, faecal neutral steroids, percentage bacterial conversion and the ratio of lithocholic acid to deoxycholic acid concentrations. There was a statistically significant (P = 0.021) association of the presence of chenodeoxycholic acid (5/8 samples) in the right-sided cases compared with the controls (3/23), odds ratio 6.26 (95% confidence interval 1.19, 32.84). A high proportion of primary bile acids has also been found in other studies of patients with a genetic predisposition to proximal bowel cancer, however this pattern may also occur in low risk groups, such as Indian vegetarians, suggesting that they may predispose to right-sided bowel cancer only in the presence of other, as yet unknown factors. If bile acids are involved in the causation of large bowel cancer, they may be part of a complex set of interacting factors.

Anaerobic utilization of alkylbenzenes and n-alkanes from crude oil in an enrichment culture of denitrifying bacteria affiliating with the beta-subclass of Proteobacteria

Denitrifying bacteria were enriched from freshwater sediment with added nitrate as electron acceptor and crude oil as the only source of organic substrates. The enrichment cultures were used as laboratory model systems for studying the degradative potential of denitrifying bacteria with respect to crude oil constituents, and the phylogenetic affiliation of denitrifiers that are selectively enriched with crude oil. The enrichment culture exhibited two distinct growth phases. During the first phase, bacteria grew homogeneously in the aqueous phase, while various C1-C3 alkylbenzenes, but no alkanes, were utilized from the crude oil. During the second phase, bacteria also grew that formed aggregates, adhered to the crude oil layer and emulsified the oil, while utilization of n-alkanes (C5 to C12) from the crude oil was observed. During growth, several alkylbenzoates accumulated in the aqueous phase, which were presumably formed from alkylbenzenes. Application of a newly designed, fluorescently labelled 16S rRNA-targeted oligonucleotide probe specific for the Azoarcus/Thauera group within the beta-subclass of Proteobacteria revealed that the majority of the enriched denitrifiers affiliated with this phylogenetic group.

Degradative capacities and 16S rRNA-targeted whole-cell hybridization of sulfate-reducing bacteria in an anaerobic enrichment culture utilizing alkylbenzenes from crude oil

A mesophilic sulfate-reducing enrichment culture growing anaerobically on crude oil was used as a model system to study which nutritional types of sulfate-reducing bacteria may develop on original petroleum constituents in oil wells, tanks, and pipelines. Chemical analysis of oil hydrocarbons during growth revealed depletion of toluene and o-xylene within 1 month and of m-xylene, o-ethyltoluene, m-ethyltoluene, m-propyltoluene, and m-isopropyltoluene within approximately 2 months. In anaerobic counting series, the highest numbers of CFU (6 x 10(6) to 8 x 10(6) CFU ml-1) were obtained with toluene and benzoate. Almost the same numbers were obtained with lactate, a substrate often used for detection of the vibrio-shaped, incompletely oxidizing Desulfovibrio sp. In the present study, however, lactate yielded mostly colonies of oval to rod-shaped, completely oxidizing, sulfate-reducing bacteria which were able to grow slowly on toluene or crude oil. Desulfovibrio species were detected only at low numbers (3 x 10(5) CFU ml-1). In agreement with this finding, a fluorescently labeled, 16S rRNA-targeted oligonucleotide probe described in the literature as specific for members of the Desulfovibrionaceae (suggested family) hybridized only with a small portion (< 5%) of the cells in the enrichment culture. These results are consistent with the observation that known Desulfovibrio species do not utilize aromatic hydrocarbons, the predominant substrates in the enrichment culture. All known sulfate-reducing bacteria which utilize aromatic compounds belong to a separate branch, the Desulfobacteriaceae (suggested family). Most members of this family are complete oxidizers. For specific hybridization with members of this branch, the probe had to be modified by a nucleotide exchange. Indeed, this modified probe hybridized with more than 95% of the cells in the enrichment culture. The results show that completely oxidizing, alkylbenzene-utilizing sulfate-reducing bacteria rather than Desulfovibrio species have to be considered in attempts to understand the microbiology of sulfide production in oil wells, tanks, and pipelines when no electron donors other than the indigenous oil constituents are available.

Metabolism of Hydroxydibenzofurans, Methoxydibenzofurans, Acetoxydibenzofurans, and Nitrodibenzofurans by Sphingomonas sp. Strain HH69

The metabolism of 11 substituted dibenzofurans by the dibenzofuran-degrading Sphingomonas sp. strain HH69 was investigated. Strain HH69 utilizes 2-, 3-, and 4-acetoxydibenzofuran as well as 2-, 3-, and 4-hydroxydibenzofuran as sole sources of carbon and energy. The degradation of acetoxydibenzofurans is initiated by hydrolysis of the ester bonds, yielding the corresponding hydroxydibenzofurans and acetate. Strain HH69 grew on 2-methoxydibenzofuran only after it was adapted to the utilization of 5-methoxysalicylic acid, whereas 3- and 4-methoxydibenzofuran as well as 2- and 3-nitrodibenzofuran were only cooxidized. During the breakdown of all eight hydroxy-, methoxy-, and nitrodibenzofurans studied here, the corresponding substituted salicylic acids accumulated in the culture broth. In the cases of 2- and 3-hydroxydibenzofuran as well as 2- and 3-nitrodibenzofuran, salicylic acid was also formed. Those four dibenzofurans which did not serve as carbon sources for strain HH69 were converted to a nonutilizable salicylic acid derivative. From turnover experiments with the mutant HH69/II, which is deficient in meta-cleavage, 2,2(prm1),3,4(prm1)-tetrahydroxybiphenyl, 2,2(prm1),3-trihydroxy-5(prm1)-methoxybiphenyl, 2,2(prm1),3-trihydroxy-5(prm1)-nitrobiphenyl, and 2,2(prm1),3-trihydroxy-4(prm1)-nitrobiphenyl were isolated as the main products formed from 3-hydroxydibenzofuran, 2-methoxydibenzofuran, and 2- and 3-nitrodibenzofuran, respectively. These results indicate significant regioselectivity for the dioxygenolytic cleavage of the ether bond of these monosubstituted dibenzofurans, with a preference for the nonsubstituted aromatic nucleus. Substituted trihydroxybiphenyls are converted further by meta-cleavage followed by the removal of the side chain of the resulting product. A stepwise degradation of this side chain was found to be involved in the metabolism of 2-hydroxydibenzofuran.

Biotransformation of diphenyl ether by the yeast Trichosporon beigelii SBUG 752

Trichosporon beigelii SBUG 752 was able to transform diphenyl ether. By TLC, HPLC, GC, GC-MS, NMR- and UV-spectroscopy, several oxidation products were identified. The primary attack was initiated by a monooxygenation step, resulting in the formation of 4-hydroxydiphenyl ether, 2-hydroxydiphenyl ether and 3-hydroxydiphenyl ether (48:47:5). Further oxidation led to 3,4-dihydroxydiphenyl ether. As a characteristic product resulting from the cleavage of an aromatic ring, the lactone of 2-hydroxy-4-phenoxymuconic acid was identified. The possible mechanism of ring cleavage to yield this metabolite is discussed.

Anaerobic oxidation of hydrocarbons in crude oil by new types of sulphate-reducing bacteria

Many crude oil constituents are biodegradable in the presence of oxygen; however, a substantial anaerobic degradation has never been demonstrated. An unusually low content of n-alkanes in oils of certain deposits is commonly attributed to selective utilization of these hydrocarbons by aerobic microorganisms. On the other hand, oil wells and production fluids were shown to harbour anaerobic sulphate-reducing bacteria, but their actual electron donors and carbon sources were unknown. On the basis of nutritional properties of various bacterial isolates it was assumed that fatty acids and H2 are potential electron donors for sulphate reduction in situ. Here we demonstrate that hydrocarbons in crude oil are used directly by sulphate-reducing bacteria growing under strictly anoxic conditions. A moderately thermophilic pure culture selectively utilizes n-alkanes in oil for sulphate reduction to sulphide. In addition, a mesophilic sulphate-reducing enrichment culture is shown to oxidize alkylbenzenes in oil. Thus, sulphate-reducing bacteria utilizing aliphatic and aromatic hydrocarbons as electron donors may present a significant source of sulphide in oil deposits and oil production plants.

Genetic factors determining thrombosis and fibrinolysis

Raised plasma levels of fibrinogen, factor VIIc, and plasminogen activator inhibitor-1 (PAI-1) are associated with an increased risk of ischemic heart disease. Levels of these proteins are determined in part by environmental influences such as smoking and dietary fat intake. However, genetic variation explains much of the interindividual variation in plasma levels of these proteins not accounted for by environmental factors. We previously investigated the DNA variation at the fibrinogen gene locus and showed that BclI restriction fragment length polymorphism (RFLP) of the beta-fibrinogen gene is associated with between-person differences in plasma fibrinogen levels. This RFLP is unlikely to be the functional base change itself, since it lies downstream of the gene. The rate-limiting step in the production of the mature fibrinogen molecule in the human hepatoma cell-line HepG2 is the synthesis of the beta-polypeptide chain, which in turn is influenced by the amount of messenger (mRNA) available. One possibility is that BclI RFLP is in linkage disequilibrium with a base change in the region of the beta-gene controlling synthesis of its mRNA and ultimately of fibrinogen protein. We identified a base change in the 5'-flanking region of the beta-fibrinogen gene that is in linkage disequilibrium with the BclI RFLP, that is associated with plasma fibrinogen levels, and that may be involved in control of fibrinogen gene expression. For the factor VII gene, we identified a polymorphism, detected after Msp I digestion of polymerase chain reaction (PCR)-amplified genomic DNA, that is strongly associated with factor VII coagulant activity (factor VIIc). The base change that creates the Msp I polymorphism is a G to A substitution, leading to the replacement of arginine (Arg) with glutamine (Gln) in the protein product of the M2 allele. In a sample of 284 men from the United Kingdom the frequency of the Gln allele (M2 loss of cutting site) is 0.1, and individuals of genotype Arg/Gln have factor VIIc levels 22% below the sample mean. In this sample, the Msp I genotype was found to be the strongest predictor of factor VIIc, accounting for 20.2% of the variance, with cholesterol accounting for an additional 3.5%. Three individuals homozygous for the Gln allele had both low factor VIIc and low factor VII protein concentrations. The conformation of the factor VII Gln may be different from that of the Arg protein, affecting its intracellular processing, secretion, turnover in plasma, or activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Metabolism of dibenzo-p-dioxin by Sphingomonas sp. strain RW1

In the course of our screening for dibenzo-p-dioxin-utilizing bacteria, a Sphingomonas sp. strain was isolated from enrichment cultures inoculated with water samples from the river Elbe. The isolate grew with both the biaryl ethers dibenzo-p-dioxin and dibenzofuran (DF) as the sole sources of carbon and energy, showing doubling times of about 8 and 5 h, respectively. Biodegradation of the two aromatic compounds initially proceeded after an oxygenolytic attack at the angular position adjacent to the ether bridge, producing 2,2',3-trihydroxydiphenyl ether or 2,2',3-trihydroxybiphenyl from the initially formed dihydrodiols, which represent extremely unstable hemiacetals. Results obtained from determinations of enzyme activities and oxygen consumption suggest meta cleavage of the trihydroxy compounds. During dibenzofuran degradation, hydrolysis of 2-hydroxy-6-oxo-6-(2-hydroxyphenyl)-hexa-2,4-dienoate yielded salicylate, which was branched into the catechol meta cleavage pathway and the gentisate pathway. Catechol obtained from the product of meta ring fission of 2,2',3-trihydroxydiphenyl ether was both ortho and meta cleaved by Sphingomonas sp. strain RW1 when this organism was grown with dibenzo-p-dioxin.

Adolescent smokers seen in general practice: health, lifestyle, physical measurements, and response to antismoking advice

OBJECTIVE

To compare physical, lifestyle, and health characteristics of adolescent smokers and non-smokers and their initial response to anti-smoking counselling.

DESIGN

Adolescents aged 13, 15, and 17 years were identified from age-sex registers and invited by letter for a general practice health check.

SETTING

Three general practices in the MRC general practice research framework.

MAIN OUTCOME MEASURES

Blood pressure, body mass index, saliva cotinine concentration, peak flow rate, alcohol consumption, exercise, duration of sleep, and stated persistent health problems.

RESULTS

73% of the adolescents (491) attended for the health check. A total of 68 (14%) were regular smokers. By age 17 those who smoked regularly had a significantly lower systolic blood pressure than those who had never smoked regularly (by 6 mm Hg; p = 0.025) despite a significantly higher body mass index (by 1.5; p <0.001) [corrected]. Cotinine concentrations increased with smoking exposure, from 0.7 ng/ml when no family member smoked to 155 ng/ml in active smokers of six or more cigarettes a week. Significantly more regular smokers than never regular smokers drank greater than or equal to 8 g alcohol a day (chi 2 = 15.2 adjusted for age and sex p less than 0.001); regular smokers exercised less (1.0 hrs/week in boys and 0.8 hrs/week in girls v 3.4 hrs/week in boys and 2.2 hrs/week in girls; p less than 0.001) and slept less (8.0 hrs/night v 8.5 hrs/night at age 17; p less than 0.005). Persistent health problems, mostly asthma or allergic symptoms, were reported by 25% (17/68) of the smokers and 16% (60/381) of the non-smokers. Of the smokers given counselling, 60% (26/43) made an agreement with the practice doctor or nurse to give up smoking.

CONCLUSION

General practice is an appropriate setting for adolescents to receive advice on healthy lifestyle, which should not focus solely on smoking.

Transformation of 3-chlorodibenzofuran by Pseudomonas sp. HH69

The dibenzofuran-degrading bacterial strain Pseudomonas sp. HH69 showed high oxidative activity towards 3-chlorodibenzofuran (3CDF). During the co-metabolic turnover of 3CDF large amounts of 4-chlorosalicylate and temporarily small amounts of salicylate were excreted. Simultaneously a yellow colour appeared due to the excretion of two polar products. Conversion of 3CDF by a mutant, derived from Pseudomonas sp. HH69 and defective in 2,3-dihydroxybiphenyl-1,2-dioxygenase led to the formation of equal quantities of 4'-chloro-2,2',3-trihydroxybiphenyl (4'CTHBP) and 4-chloro-2,2',3-trihydroxybiphenyl (4CTHBP). Crude extracts of the wild type transformed 4'CTHBP to 4-chlorosalicylate, whilst 4CTHBP was transformed to salicylate. Hence, we propose a non-selective initial attack on both aromatic rings of 3CDF and a degradative pathway for the resulting chlorotrihydroxybiphenyls.

A common genetic polymorphism associated with lower coagulation factor VII levels in healthy individuals

We have identified a genetic polymorphism of factor VII that is strongly associated with plasma factor VII coagulant activity (factor VIIc) in healthy individuals from the United Kingdom. This polymorphism was detected after Msp I digestion of polymerase chain reaction-amplified genomic DNA. In a sample of 284 men, the frequency of the M2 allele (loss of cutting site) is 0.1, and individuals with the M1M2 genotype have factor VIIc levels 22% below the sample mean (p less than 0.0001). Msp I genotype was found to be the strongest predictor of factor VIIc, accounting for 20.2% of the variance, with cholesterol accounting for an additional 3.5%. The base change that gives rise to the Msp I polymorphism is a G-to-A substitution in the codon for amino acid 353, leading to replacement of arginine (Arg) with glutamine (Gln) in the protein product of the M2 allele (designated Gln 353). Three individuals homozygous for the M2 allele have both low factor VIIc and low factor VII protein concentrations. The conformation of the Gln 353 molecule may be different from that of the Arg 353 protein, affecting its intracellular processing, secretion, turnover in plasma, or activity. In view of its association with lower factor VIIc levels, possession of the M2 allele may confer protection against thrombosis and myocardial infarction.

Degradation of 1,2,4-Trichloro- and 1,2,4,5-Tetrachlorobenzene by Pseudomonas Strains

Two Pseudomonas sp. strains, capable of growth on chlorinated benzenes as the sole source of carbon and energy, were isolated by selective enrichment from soil samples of an industrial waste deposit. Strain PS12 grew on monochlorobenzene, all three isomeric dichlorobenzenes, and 1,2,4-trichlorobenzene (1,2,4-TCB). Strain PS14 additionally used 1,2,4,5-tetrachlorobenzene (1,2,4,5-TeCB). During growth on these compounds both strains released stoichiometric amounts of chloride ions. The first steps of the catabolism of 1,2,4-TCB and 1,2,4,5-TeCB proceeded via dioxygenation of the aromatic nuclei and furnished 3,4,6-trichlorocatechol. The intermediary cis -3,4,6-trichloro-1,2-dihydroxycyclohexa-3,5-diene (TCB dihydrodiol) formed from 1,2,4-TCB was rearomatized by an NAD + -dependent dihydrodiol dehydrogenase activity, while in the case of 1,2,4,5-TeCB oxidation the catechol was obviously produced by spontaneous elimination of hydrogen chloride from the initially formed 1,3,4,6-tetrachloro-1,2-dihydroxycyclohexa-3,5-diene. Subsequent ortho cleavage was catalyzed by a type II catechol 1,2-dioxygenase producing the corresponding 2,3,5-trichloromuconate which was channeled into the tricarboxylic acid pathway via an ordinary degradation sequence, which in the present case included 2-chloro-3-oxoadipate. From the structure-related compound 2,4,5-trichloronitrobenzene the nitro group was released as nitrite, leaving the above metabolite as 3,4,6-trichlorocatechol. Enzyme activities for the oxidation of chlorobenzenes and halogenated metabolites were induced by both strains during growth on these haloaromatics and, to a considerable extent, during growth of strain PS12 on acetate.

Metabolism of Dibenzofuran by Pseudomonas sp. Strain HH69 and the Mixed Culture HH27

A Pseudomonas sp. strain, HH69, and a mixed culture, designated HH27, were isolated by selective enrichment from soil samples. The pure strain and the mixed culture grew aerobically on dibenzofuran as the sole source of carbon and energy. Degradation proceeded via salicylic acid which was branched into the gentisic acid and the catechol pathway. Both salicylic acid and gentisic acid accumulated in the culture medium of strain HH69. The acids were slowly metabolized after growth ceased. The enzymes responsible for their metabolism showed relatively low activities. Besides the above-mentioned acids, 2-hydroxyacetophenone, benzopyran-4-one (chromone), several 2-substituted chroman-4-ones, and traces of the four isomeric monohydroxydiben-zofurans were identified in the culture medium. 2,2′,3-Trihydroxybiphenyl was isolated from the medium of a dibenzofuran-converting mutant derived from parent strain HH69, which can no longer grow on dibenzofuran. This gives evidence for a novel type of dioxygenases responsible for the attack on the biarylether structure of the dibenzofuran molecule. A meta -fission mechanism for cleavage of the dihydroxylated aromatic nucleus of 2,2′,3-trihydroxybiphenyl is suggested as the next enzymatic step in the degradative pathway.

Dietary and other characteristics relevant for coronary heart disease in men of Indian, West Indian and European descent in London

The origins of the high standardized mortality ratio (SMR) for coronary heart disease (CHD) among Indians in Britain, and the low SMR for West Indian immigrants, have been explored by a community survey in London. Serum lipoproteins, plasma glucose, haemostatic factors and other putative risk characteristics were measured in 75 Indian, 64 European and 24 West Indian men aged 45-54 years. These represented 81% of men registered with a general practice and resident within a defined area. In 51 men, diet was assessed by 5-day weighed inventory. Plasma phospholipid fatty acids (PFA) were measured in 18 Indians and 19 Europeans with dietary records. The relatively high HDL and HDL2-cholesterol concentrations, low LDL-cholesterol concentration, reduced fat intake, increased ratio of dietary polyunsaturated/saturated fat, relatively frequent use of alcohol, and lack of obesity in West Indians accorded with their low SMR from CHD. By contrast, only the relatively low HDL and HDL2-cholesterol concentrations, infrequency of alcohol consumption, and lower proportion of PFA as n-3 fatty acids of marine origin afforded explanations for the high SMR of Indians. Hyperglycaemia appeared similarly prevalent in Indians and West Indians, but less common in Europeans. Of the haemostatic factors, West Indians had a relatively low VIIc (not statistically significant), while Indians had an increased platelet count and reduced platelet volume. Improved understanding of these ethnic differences in CHD mortality may depend upon elucidation of the contrasts in HDL-cholesterol concentration.

Association between dietary fat intake and plasma factor VII coagulant activity--a predictor of cardiovascular mortality

Repeated measurements were made in 8 adults of factor VII coagulant activity (VIIc) and fibrinogen concentration (two haemostatic variables associated with cardiovascular mortality), together with factor VII concentration, factor X, prothrombin, and serum cholesterol and triglyceride concentrations, while the usual diet was recorded by precise weighing over 12-14 days. In 6 subjects measurements were continued while low-fat and high-fat diets were taken for a further 2 and 3 weeks respectively. Plasma VIIc was related positively and independently to fat and protein intake, whereas factor VII concentration was associated only with protein consumption. In a second study, consumption of 50% extra energy for one day increased VIIc significantly when taken mainly as fat but not when taken mostly as carbohydrate. The character of the VIIc response to fat intake suggested an association with post-prandial lipaemia. A high fat intake may lead not only to coronary atheroma but also to fibrin deposition and thrombus formation through direct activation of the coagulation system.

Effects of oral contraceptives and obesity on protein C antigen

In 24 women using oral contraceptives, protein C antigen was higher than in 24 women of the same age and of the same degree of obesity who were not using OC. In the pooled data for all 48 women, there was an increase in protein C of about 1% (of standard) for each 1.0 mm increase in skinfold thickness. Protein C tends to be high rather than low in circumstances predisposing to thrombosis.

Cumulative scales for the measurement of agoraphobia

The questionnaire responses of 559 agoraphobic subjects were analysed to see whether there was a shared hierarchical pattern of fear and avoidance. The items were divided on the basis of a principal component analysis into 13 loading on an Agoraphobia factor and eight on a Claustrophobia factor. When analysed with Guttman Scaling Analysis valid cumulative scales were found for each factor. These scales were replicated in three independent cohorts of subjects and met the most stringent scaling requirements. The scales produced three valid scores of severity for each individual, the first describing exactly which Agoraphobic items the subject avoids, the second describing Agoraphobic items feared and the third Claustrophobic items avoided. Since it is possible to deduce the current pattern of fear and avoidance from the scores, they can be used to summarize the clinical state of an individual client or for making precise descriptive comparisons between agoraphobics . The scales also indicate that agoraphobics do not develop their own unique set of difficulties from the possible pool of problems, but acquire an ordered set of difficulties, the order being shared by other agoraphobics .