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PubMed1990

Chlorsulfuron modifies biosynthesis of acyl Acid substituents of sucrose esters secreted by tobacco trichomes.

Sucrose esters and duvatrienediol diterpenes are principal constituents formed in and secreted outside head cells of trichomes occurring on surfaces of Nicotiana tabacum. Using trichome-bearing epidermal peels prepared from midveins of N. tabacum cv T.I. 1068 leaves, we found that chlorsulfuron reduced and modified radiolabeling of sucrose ester acyl acids derived from branched-chain amino acid metabolism. The herbicide did not effect formation and exudation of diterpenes which are products of isoprenoid metabolism. Treatment with 1.0 micromolar chlorsulfuron affected 8.5- and 6.3-fold reductions in radiolabeling of methylvaleryl and methylbutyryl groups of sucrose esters, respectively, and concomitant increases of 9- and 9.8-fold in radiolabeling of straight chain valeryl and butyryl groups, respectively. These results and others indicate that inhibition of acetolactate synthase causes an accumulation of 2-oxo-butyric acid that is utilized by enzymes common to Leu biosynthesis to form 2-oxo-valeric acid. Coenzyme A (CoA) activation of this keto acid gives rise to butyryl CoA, which is utilized to form butyryl containing sucrose esters. Alternatively, reutilization of 2-oxo-valeric acid by the same enzymes followed by CoA activation leads to valeryl containing sucrose esters. We propose that in trichome secretory cells synthase, isomerase and dehydrogenase enzymes which catalyze Leu synthesis/degredation in most tissues, convert iso-branched, anteiso-branched and straight-chain keto acids in the formation of sucrose ester acyl groups.

Journal Article↗
PubMed2005

Detection of contact hypersensitivity to corticosteroids in allergic contact dermatitis patients who do not respond to topical corticosteroids.

The delayed hypersensitivity development against topical corticosteroids which are used in allergic contact dermatitis (ACD) treatment is an important clinical problem. In our study, 41 ACD patients who did not show any response to topical corticosteroid treatment were patch tested with corticosteroid series and the commercial preparations of corticosteroids and their vehicles. In corticosteroid series, there were budesonide, bethametasone-17-valerate, triamcinolone acetonide, tixocortol pivalate, alclomethasone-17-21-dipropionate, clobetasole-17-propionate, dexamethasone-21-phosphate disodium and hydrocortisone-17-butyrate. We detected positive reaction to corticosteroids in 9 of our cases (22%) (5 single and 4 multiple). The sensitivity was mostly produced by tixocortol pivalate (6 patients). This was followed by triamcinolone acetonide (2 patients) budesonide (2 patients), alclomethasone dipropionate (2 patients), dexamethasone 21 phosphate disodium (2 patients) and betamethasone-17-valerate (1 patient). As a result, it should not be forgotten that the corticosteroids used to treat ACD patients may cause ACD themselves. In ACD patients who did not respond to corticosteroid treatment, routinely applying patch test with corticosteroids should be helpful in directing the treatment.

Administration, Topical↗
PubMed2003

Pharmacological profiles of high-concentration (20 microg/g) tacalcitol ointment: effects on cutaneous inflammation, epidermal proliferation, and differentiation in mice.

This study focused on the effects of tacalcitol (1,24 (R) (OH)2D3, TV-02) ointment (20 micro g/g) on cutaneous inflammation, epidermal proliferation, and differentiation and compared them with tacalcitol ointment (2 micro g/g) and other anti-psoriatic ointments using hairless mice. Tacalcitol ointment (0, 2 and 20 micro g/g) significantly inhibited 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced cutaneous inflammation, histopathologically. The effect of tacalcitol ointment (20 micro g/g) on cutaneous inflammation was much stronger than that of tacalcitol ointment (0, 2 micro g/g), and as effective as calcipotriol ointment (50 micro g/g) or betamethasone valerate ointment (1.2 mg/g). Tacalcitol ointment (20 micro g/g) also significantly inhibited TPA-induced myeloperoxidase (MPO) activity, as effectively as calcipotriol ointment (50 micro g/g) or betamethasone valerate ointment (1.2 mg/g). The effect of tacalcitol ointment on epidermal proliferation [ornithine decarboxylase (ODC) activity] and differentiation [transglutaminase (TGase) activity] was dose-dependent from 0 micro g/g to 20 micro g/g. The effect of tacalcitol ointments on epidermal proliferation was significant at the doses of 2 micro g/g and 20 micro g/g, and that on epidermal differentiation was significant at the doses of 0.2 micro g/g or more. The effect of tacalcitol ointment (20 micro g/g) on epidermal differentiation was significantly stronger than tacalcitol ointment (2 micro g/g). In this study, tacalcitol ointment (20 micro g/g) was found to have a marked effect on cutaneous inflammation and improved effect on epidermal differentiation, although tacalcitol ointment (2 micro g/g) also had significant effects on epidermal proliferation and differentiation. These findings support the clinical effectiveness of tacalcitol ointment (20 micro g/g) against psoriasis.

Administration, Topical↗
PubMed1982

The dilution of proprietary corticosteroid ointments--an attempt to evaluate relative clinical potencies.

Ten subjects were assessed using the vasoconstrictor assay technique in a double-blind study in order to evaluate the potencies of several diluted and undiluted proprietary corticosteroid ointments. Results showed that clobetasol propionate 0.05% (Dermovate) ointment at a dilution of one part in ten (clobetasol propionate 0.005%) in white soft paraffin was equipotent with betamethasone valerate 0.1% (Betnovate) ointment; and no difference in potency was demonstrated between beclomethasone dipropionate 0.025% (Propaderm), betamethasone valerate 0.1% (Betnovate) and clobetasone butyrate 0.05% (Eumovate).

Administration, Topical↗
PubMed1987

Cyproterone acetate, an alternative gestagen in postmenopausal oestrogen/gestagen therapy.

Seventy-six healthy, early postmenopausal women (aged 45-54 years) were allocated to 2 years of treatment with a cyclic combination of 2 mg oestradiol valerate (21 d) and 1 mg cyproterone acetate (11 d) or placebo. Sixty-five women (86%) completed the study. In the placebo group the bone mineral content in the forearms (measured by single photon absorptiometry) and the bone mineral content in the lumbar spine and total skeleton (measured by dual photon absorptiometry) decreased significantly and at the same magnitude (P less than 0.001), whereas all bone mass measurements remained unchanged in the hormone-treated group. In the hormone-treated group there was a significant decrease in biochemical estimates of bone turnover (serum alkaline phosphatase, serum phosphate, fasting urinary calcium and hydroxyproline), whereas these values were unchanged in the placebo treated group. We conclude that treatment with a cyclic combination of 2 mg oestradiol valerate and 1 mg cyproterone acetate is effective as prophylaxis of postmenopausal bone loss.

Calcium↗
PubMed1991

Desogestrel in hormone replacement therapy: long-term effects on bone, calcium and lipid metabolism, climacteric symptoms, and bleeding.

Seventy-three healthy, postmenopausal women, aged 45-54 years, were randomly assigned to one of three groups for 2 years of treatment: 17 beta-oestradiol 1.5 mg on days 1-12 and 17 beta-oestradiol 1.5 mg + desogestrel 150 micrograms on days 13-24 (E2/DG) or oestradiol valerate 2 mg on days 1-11 and oestradiol valerate 2 mg + medroxyprogesterone acetate 10 mg on days 12-21 (E2V/MPA) or placebo. Fifty-seven women (78%) completed the study. Bone mineral content of the distal regions of the forearms (measured by single photon absorptiometry, SPA) and bone mineral density of the spine (measured by dual energy X-ray absorptiometry, DXA) showed increases of 0.5-1% and 4-5%, respectively, in the hormone groups over 2 years. The placebo group exhibited a decrease in spinal bone density of 2% per year, and in the forearm of 2.5-3.5% per year. Biochemical estimates of bone turnover (serum alkaline phosphatase and fasting urinary calcium) decreased significantly to premenopausal levels in the hormone groups but remained unchanged in the placebo group. In both hormone groups total cholesterol decreased by about 9% (P less than 0.001), whereas low density lipoprotein cholesterol decreased by 16% in the E2/DG group and 20% in the E2V/MPA group (P less than 0.001). High density lipoprotein cholesterol showed only minor, insignificant changes in the hormone groups. The placebo group had virtually unchanged values. Climacteric symptoms, including hot flushes, were significantly reduced in both hormone groups. Bleeding occurred regularly in about 80% of the women.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1995

Synthesis and characterization of indolicidin, a tryptophan-rich antimicrobial peptide from bovine neutrophils.

Indolicidin, a novel tryptophan-rich microbicidal tridecapeptide amide isolated originally from granules of bovine neutrophils, has been prepared by optimized manual and automated protocols of stepwise solid-phase synthesis with N alpha-9-fluorenylmethyloxycarbonyl (Fmoc) amino acid derivatives. Both standard polystyrene (PS) and polyethylene glycol-polystyrene (PEG-PS) graft supports were used in combination with handles that provide C-terminal peptide amides: 5-(4-Fmoc-aminomethyl-3,5-dimethoxyphenoxy)valeric acid (PAL) or 5-(9-Fmoc-aminoxanthen-2-oxy)valeric acid (XAL). Final deprotection/cleavage was carried out with reagent K, trifluoroacetic acid-phenol-water-thioanisole-1,2-ethanedithiol (82.5:5:5:5:2.5), or reagent B, trifluoroacetic acid-phenol-water-tri(isopropyl)silane (88:5:5:2), and related cocktails. Initial purities as high as 93% were obtained immediately following cleavage. In the largest-scale synthesis carried out, 0.8 g of HPLC-purified indolicidin (> 99% pure) was obtained, representing a 39% overall yield based on C-terminal Arg(Pmc) anchored to PAL-PS-resin. The main synthetic product, and some by-products, were characterized by analytical high-performance liquid chromatography (HPLC), sequencing, and fast atom bombardment mass spectrometry (FABMS). The antimicrobial potencies of natural and synthetic indolicidin, as determined by in vitro antibacterial and antifungal assays, were identical. Further, the reactivities of natural and synthetic peptides with anti-indolicidin antibody were indistinguishable.

Animals↗
PubMed1980

The effect of various regimens of hormone therapy on serum cholesterol and triglyceride concentrations in postmenopausal women.

The serum cholesterol and triglyceride concentrations of 84 postmenopausal women both before and after 2, 6 and 12 months therapy with various regimens of hormone therapy were measured. There was little alteration in mean serum cholesterol concentration with cyclical oestrogens but both sequential mestranol and norethisterone and sequential oestradiol valerate and norgestrel significantly reduced the mean serum cholesterol concentration to a level similar to that found in age-matched premenopausal women. There was a small and sometimes significant rise in serum triglyceride concentration with cyclical oestrogens. Sequential mestranol and norethisterone significantly elevated serum triglyceride levels, but sequential oestradiol valerate and norgestrel significantly depressed them. The results suggest that the progestogenic agent norgestrel has an important role to play in reducing both serum cholesterol and triglyceride levels, and that the sequential preparations, by virtue of their greater cholesterol lowering effect, should perhaps be preferred to cyclical oestrogens.

Cholesterol↗
PubMed1992

Endometrial responses in artificial cycles: a prospective study comparing four different oestrogen dosages.

OBJECTIVE: To examine the endometrial response to four different regimens of oestrogen. DESIGN: A prospective, randomized cross-over study. SETTING: Jessop Hospital for Women, Sheffield. SUBJECTS: Twenty one women with premature ovarian failure divided into three equal groups. INTERVENTIONS: Four different regimens of hormone replacement therapy: variable, fixed 1 mg, fixed 2 mg and fixed 4 mg oestrogen dosages. Each woman received the variable dosage regimen in one cycle and crossed over to receive one of the three fixed dose regimens (1 mg, Group 1; 2 mg, Group 2; 4 mg Group 3) in another cycle. MAIN OUTCOME MEASURE: Ultrasonographic measurement of endometrial thickness and outpatient endometrial biopsy on day 19 of the artificial cycle; analysis of endometrial specimens by three separate methods: traditional histological criteria, morphometry and immunohistochemistry. RESULTS: The endometrial response was similar in those treated with the variable and the fixed 2 mg or 4 mg dosage regimens. The response was suboptimal in those treated with the fixed 1 mg dosage regimen. CONCLUSIONS: Normal endometrial development requires adequate priming of the endometrium by oestrogen, which may be administered in a sequential, variable dosage fashion, or simply by a fixed daily dosage regimen. However, the minimum daily dose required is likely to be 2 mg of oestradiol valerate. No adverse effect on the endometrium was observed at a daily dose of 4 mg oestradiol valerate, which produced plasma levels of oestradiol above the reference ranges of the natural cycle.

Adult↗
PubMed2002

Intrauterine 10 microg and 20 microg levonorgestrel systems in postmenopausal women receiving oral oestrogen replacement therapy: clinical, endometrial and metabolic response.

OBJECTIVE: The clinical and endometrial efficacy and lipid response of two different doses of intrauterine levonorgestrel were assessed in comparison with sequential oral medroxyprogesterone acetate in postmenopausal women receiving continuous oral E2-valerate. DESIGN: One-year prospective multicentre randomised control trial. SETTING: Four outpatient clinics in Oulu, Helsinki and Jyväskylä, Finland. POPULATION: A total of 163 healthy volunteer postmenopausal women with climacteric complaints or already using hormone replacement therapy (HRT). INTERVENTIONS: Subjects were randomly allocated to receive a new intrauterine system releasing 10 microg of levonorgestrel daily or an established intrauterine system (Mirena) releasing 20 microg of levonorgestrel daily or sequential oral medroxyprogesterone acetate (5mg/day, 14/30 days). All three regimens were combined with an oral daily dose of 2mg of E2-valerate. MAIN OUTCOME MEASURES: Bleeding patterns were assessed by diaries kept by the subjects. Endometrial effects were evaluated by histologic biopsies taken at the baseline and after six and 12 months of therapy. Serum concentrations of total, HDL and LDL cholesterol, triglycerides and lipoprotein(a) were determined at the baseline and after six and 12 months of therapy. RESULTS: Insertion of the smaller 10 microg levonorgestrel system was easy in 70% and difficult in 4% and that of Mirena was easy in 46% and difficult in 21% of the subjects. After six months of therapy, 43 (95.6%) of the 47 subjects receiving 10 microg levonorgestrel and 54 (98.2%) of the 55 subjects receiving 20 microg levonorgestrel had no bleeding, while the sequential medroxyprogesterone acetate regimen produced typical cyclic withdrawal bleedings. Endometrial hyperplasia was not observed in any of the treatment groups during the 12-month study. After 12 months of therapy, strong endometrial suppression was found in 46/47 and 55/55 of the subjects receiving 10 microg and 20 microg of levonorgestrel, respectively, while the endometrium was proliferative in 18/47 of the subjects in the medroxyprogesterone acetate group. Serum total cholesterol decreased in all treatment groups. HDL cholesterol increased in women receiving medroxyprogesterone acetate or the smaller intrauterine dose of levonorgestrel. CONCLUSIONS: Both intrauterine doses of levonorgestrel provided good endometrial protection in postmenopausal women on oestrogen replacement therapy. The advantage of the 10 microg system with a smaller size is the easier insertion of the system and a minimal attenuation of the favourable effects of oral oestrogen on the serum lipid profile.

Administration, Intravaginal↗
PubMed1990

GABA(B)-related activity involved in synaptic processing of somatosensory information in S1 cortex of the anaesthetized cat.

1. The possible role of GABA(B) receptor mechanisms in information processing in primary somatosensory (S1) cortex was assessed by use of extracellular recording combined with microiontophoretic methods from 161 neurones in anaesthetized, paralysed cats. 2. Baclofen-induced suppressions of cell responses were reversible and stereoselective, the (+)-isomer being inactive and the (-)-isomer having two to three times the apparent potency of gamma-aminobutyric acid (GABA). The responses measured were threshold to natural stimulation of receptive fields (RFs), responsiveness to thalamic electrical stimulation, change in RF size and magnitude of firing elicited by iontophoretic glutamate. 3. The action of GABA always was mimicked by muscimol or 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP) but not always by (-)-baclofen; in certain cases (-)-baclofen enhanced neuronal responses while the opposite occurred with GABA or with the other GABA(A) agonists. The elevation of response thresholds by (-)-baclofen was relatively stronger in peripheral than in central subregions of cutaneous RFs, by contrast with the action of muscimol which was relatively non-selective as to the area in which it was effective. 4. Glutamate-induced and thalamically-evoked cortical responses as well as spontaneous activity were differentially sensitive to the suppressant effects of muscimol and (-)-baclofen. 5. Bicuculline methiodide reversibly blocked THIP- and muscimol-induced suppressions of tactile- (air puffer)-induced S1 responses but spared those produced by (-)-baclofen. Phaclofen and delta-amino-n-valeric acid were essentially inactive as blockers of (-)-baclofen-induced effects and in fact often acted as (-)-baclofen-like agonists, phaclofen being considerably weaker than delta-amino-n-valeric acid in this respect. 6. The range of suppressant effects produced by GABA as well as by muscimol and THIP, considered in conjunction with the actions of bicuculline methiodide, suggest that the effects observed by ejected GABA are likely to be due principally to GABA(A) processes, those mediated by GABA(B) receptors largely being masked. However, GABA(B) mechanisms are extant and do appear to be active, probably presynaptically and probably at sites distal to the soma.

Anesthesia↗
PubMed2000

Effect of 2-bromo-ethane sulfonate, molybdate and chloroform on acetate consumption by methanogenic and sulfate-reducing populations in freshwater sediment.

The relative importance of methanogenesis and sulfate reduction in freshwater sediment supplemented with acetate was investigated. Addition of acetate stimulated both methane formation and sulfate reduction, indicating that an active aceticlastic population of methanogens and sulfate reducers was present in the sediment. Sulfate reducers were most important in the consumption of acetate. However, when sulfate reducers were inhibited, acetate was metabolised at a similar rate by methanogens. Acetate, propionate and valerate accumulated only when both processes were inhibited by the combined addition of 2-bromo-ethane sulfonate and molybdate. The relative amounts of acetate, propionate and valerate were 93, 6 and 1 mol%, respectively. These results demonstrate the role of acetate as a key intermediate in the terminal step of organic matter mineralisation in the sediment. Addition of chloroform inhibited both methanogenesis and sulfate reduction. We studied the inhibitory effect of CHCl(3) on homoacetogenic bacteria, sulfate-reducing bacteria and methanogens. The results showed that inhibition by CHCl(3) correlates with microorganisms, which operate the acetyl-CoA cleavage pathway. We propose that chloroform can be used to elucidate the role of different metabolic types of sulfate reducers to sulfate reduction in natural environments.

Journal Article↗
PubMed2002

Ocular disposition of ganciclovir and its monoester prodrugs following intravitreal administration using microdialysis.

The present study was carried out to delineate the ocular pharmacokinetics of ganciclovir (GCV) following intravitreal administration. Another objective was to achieve sustained therapeutic concentrations of GCV in the vitreous over a prolonged period of time using its acyl monoester prodrugs (acetate, propionate, butyrate, and valerate). New Zealand albino male rabbits (2-2.5 kg) were kept under anesthesia. A concentric microdialysis probe was implanted in the vitreous using a 21-guage needle, and a linear microdialysis probe was implanted in the anterior chamber across the cornea using a 25-guage needle. The probes were perfused with isotonic phosphate buffer saline (pH 7.4) at a flow rate of 2 microl/min. The drugs were administered (0.2 micromoles) intravitreally and the samples were collected every 20 min over a period of 10 h. The vitreal terminal elimination half-life (t(1/2)beta) of GCV was found to be 426 +/- 109 min. The hydrolysis rate and vitreal clearance of the prodrugs increased with the ascending ester chain length. The vitreal elimination half-lives (t(1/2k10)) of GCV, acetate, propionate, butyrate, and valerate esters of GCV were 170 +/- 37, 117 +/- 50, 122 +/- 13, 55 +/- 26, and 107 +/- 14 min, respectively. A parabolic relationship was observed between the vitreal elimination rate constant and the ester chain length. Mean residence time (MRT) of the regenerated GCV following prodrug administration was found to be three to four times the value obtained after GCV injection. In conclusion, these studies have shown that the ester prodrugs generated therapeutic concentrations of GCV in vivo, and the MRT of GCV could be enhanced by 3- to 4-fold through prodrug modification.

Administration, Topical↗
PubMed1984

Isolation and partial characterization of bacteria in an anaerobic consortium that mineralizes 3-chlorobenzoic Acid.

A methanogenic consortium able to use 3-chlorobenzoic acid as its sole energy and carbon source was enriched from anaerobic sewage sludge. Seven bacteria were isolated from the consortium in mono- or coculture. They included: one dechlorinating bacterium (strain DCB-1), one benzoate-oxidizing bacterium (strain BZ-2), two butyrate-oxidizing bacteria (strains SF-1 and NSF-2), two H(2)-consuming methanogens (Methanospirillum hungatei PM-1 and Methanobacterium sp. strain PM-2), and a sulfate-reducing bacterium (Desulfovibrio sp. strain PS-1). The dechlorinating bacterium (DCB-1) was a gram-negative, obligate anaerobe with a unique "collar" surrounding the cell. A medium containing rumen fluid supported minimal growth; pyruvate was the only substrate found to increase growth. The bacterium had a generation time of 4 to 5 days. 3-Chlorobenzoate was dechlorinated stoichiometrically to benzoate, which accumulated in the medium; the rate of dechlorination was ca. 0.1 pmol bacterium day. The benzoate-oxidizing bacterium (BZ-2) was a gram-negative, obligate anaerobe and could only be grown as a syntroph. Benzoate was the only substrate observed to support growth, and, when grown in coculture with M. hungatei, it was fermented to acetate and CH(4). One butyrate-oxidizing bacterium (NSF-2) was a gram-negative, non-sporeforming, obligate anaerobe; the other (SF-1) was a gram-positive, sporeforming, obligate anaerobe. Both could only be grown as syntrophs. The substrates observed to support growth of both bacteria were butyrate, 2-dl-methylbutyrate, valerate, and caproate; isobutyrate supported growth of only the sporeforming bacterium (SF-1). Fermentation products were acetate and CH(4) (from butyrate, isobutyrate, or caproate) or acetate, propionate, and CH(4) (from 2-dl-methylbutyrate or valerate) when grown in coculture with M. hungatei. A mutualism among at least the dechlorinating, benzoate-oxidizing, and methane-forming members was apparently required for utilization of the 3-chlorobenzoate substrate.

Journal Article↗
PubMed1988

Effect of pentoses and pentitols on fermentation of hay by mixed populations of ruminal microorganisms.

Consecutive batch culture, a technique which involves sequential transfer of cultures to fresh medium at regular intervals, was used to establish mixed ruminal-microbial populations in an anaerobic medium containing highly digestible hay. Once volatile fatty acid production was stable, perturbations were imposed in consecutive cultures by the addition of one of each of the following pentoses or analogous pentitols: l-arabinose, d-lyxose, d-ribose, d-xylose, l-arabitol, d-arabitol (lyxitol), ribitol, and xylitol. With the exception of d-lyxose, the addition of pentoses caused marked increases in propionate and valerate production, and except for d-arabitol, pentitol addition caused increases in butyrate and valerate production. On transfer to and continued incubation in the control medium, volatile fatty acid production reverted to preperturbed levels. The presence of pentitols and pentoses significantly reduced the endpoint pH of cultures and the proportion of hay that was fermented. With all added substrates, the response to the perturbation was at its maximum within one incubation (i.e., within 48 h). Similarly, the variables being monitored all returned to control levels within one incubation. On the basis of these results, it is suggested that changes were related to the need to maintain a redox balance within anaerobic cultures rather than any significant changes in the microbial population that was present.

Journal Article↗
PubMed1994

Anaerobic degradation of normal- and branched-chain Fatty acids with four or more carbons to methane by a syntrophic methanogenic triculture.

Syntrophic degradation of normal- and branched-chain fatty acids with 4 to 9 carbons was investigated with a mesophilic syntrophic isobutyrate-butyrate-degrading triculture consisting of the non-spore-forming, syntrophic, fatty acid-degrading, gram-positive rod-shaped strain IB, Methanobacterium formicicum T1N, and Methanosarcina mazei T18. This triculture converted butyrate and isobutyrate to methane and converted valerate and 2-methylbutyrate to propionate and methane. This triculture also degraded caproate, 4-methylvalerate, heptanoate, 2-methylhexanoate, caprylate, and pelargoate. During the syntrophic conversion of isobutyrate and butyrate, a reversible isomerization between butyrate and isobutyrate occurred; isobutyrate and butyrate were isomerized to the other isomeric form to reach nearly equal concentrations and then their concentrations decreased at the same rates. Butyrate was an intermediate of syntrophic isobutyrate degradation. When butyrate was degraded in the presence of propionate, 2-methylbutyrate was synthesized from propionate and isobutyrate formed from butyrate. During the syntrophic degradation of valerate, isobutyrate, butyrate, and 2-methylbutyrate were formed and then degraded. During syntrophic degradation of 2-methylbutyrate, isobutyrate and butyrate were formed and then degraded.

Journal Article↗
PubMed2002

Biotransformation and bioconcentration of steroid estrogens by Chlorella vulgaris.

The biotransformation and bioconcentration of natural and synthetic steroid estrogens by Chlorella vulgaris were investigated by using batch-shaking experiments with incubation for 48 h in the light or dark. Estradiol and estrone were interconvertible in both light and dark conditions; however, this biotransformation showed a preference for estrone. In the light, 50% estradiol was further metabolized to an unknown product. Apart from biotransformation, estrone, as well as hydroxyestrone, estriol, and ethinylestradiol, was relatively stable in the algal culture, whereas estradiol valerate was hydrolyzed to estradiol and then to estrone within 3 h of incubation. All of the tested estrogens exhibited a degree of partitioning to C. vulgaris; however, the concentrations of estriol, hydroxyestrone, ethinylestradiol, and estradiol valerate were always below the quantification limits. For estradiol and estrone, the partitioning of these estrogens in the algal extracts to the filtrates was <6% of the total amount present. The average concentration factor for estrone was ca. 27; however, the concentration factor for estradiol was not reported since no equilibrium was reached between the aqueous solution and that within the cells due to continuing biotransformation.

Chlorella↗
PubMed1967

Arginine and ornithine catabolism by Clostridium botulinum.

Clostridium botulinum 62-A was shown to catabolize l-arginine via citrulline to ornithine, NH(3), and CO(2). The individual enzymes of the dihydrolase system were all demonstrated in extracts of cells, spores, and germinated spores. There was no liberation of urea from l-arginine, so no functional arginase enzyme is present, but there was some transamidinase activity in cell extracts. l-Ornithine was degraded at a significant rate by cells grown in an l-ornithine-supplemented medium; it was partially decarboxylated to putrescine and partially fermented to NH(3), CO(2), volatile acids, and delta-aminovaleric acid. Results from the fermentation of l-ornithine-C(14), -1-C(14), and -2-C(14) demonstrated that essentially all of the CO(2) was derived from carbon 1, and volatile acids from carbons 2 to 5. Assays for the products of l-ornithine-C(14) fermentation revealed that the volatile acids consisted of acetate, propionate, valerate, and butyrate (in order of decreasing concentrations), and that delta-amino-valerate was the primary reduced product. A small amount of citrulline was formed during the fermentation. The carbon and redox balances indicated that l-ornithine is fermented as a single substrate. Preliminary experiments demonstrated that the fermentation of l-ornithine is carried out by cell extracts with the production of volatile acids.

Arginase↗