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At least 1,459 records · Page 81Linked to original sources
PubMed1995

Cerebral toxoplasmosis in childhood and adult HIV infection treated with 1-4 hydroxynaphthoquinone and rapid desensitization with pyrimethamine.

BACKGROUND: We describe a child and an adult infected with the human immunodeficiency virus (HIV) who developed cerebral lesions consistent with toxoplasmosis. A biopsy in the child and IgG ELISA in both patients confirmed the diagnosis of Toxoplasma gondii. The patients were initially treated with pyrimethamine, however, computerized tomography studies (CT scan) revealed progression of a left frontal and temporoparietal lesion. Therapy in the child was changed to pyrimethamine, clindamycin, and azithromycin. Repeat CT scan showed further disease progression and therapy was changed to high-dose pyrimethamine (3 mg/kg/d) and azithromycin. A subsequent CT scan disclosed further radiologic progression with increasing edema. The adult patient developed a maculopapular rash during attempted treatment with pyrimethamine. METHODS: Introduction of 2 (trans-4[4 chlorophenol] cyclohexy[3-hydroxy-1, 4 naphthoquinone] (HNPQ) an experimental antiparasitic compound previously used only in adult HIV clinical trials, was instituted in the child and rapid oral desensitization to pyrimethamine was initiated in the adult patient. RESULTS: HNPQ resulted in resolution of the cerebral lesion in the child and rapid oral desensitization to pyrimethamine produced an excellent clinical response in the adult. To our knowledge, these are the first cases of childhood and adult cerebral toxoplasmosis treated successfully with HNPQ and rapid oral desensitization to pyrimethamine. CONCLUSION: HNPQ and pyrimethamine desensitization should be considered as alternate modes of therapy in patients who become intolerant or fail to respond to traditional therapy for toxoplasmosis.

AIDS-Related Opportunistic Infections↗
PubMed1994

Degradation of aromatic compounds by Trichosporon sp.

When cultured in liquid media, samples of the yeast Trichosporon grow readily and degrade phenol; glutamate was found to stimulate both fungal growth and phenol catabolism, with a distinctive lag. In addition, this same strain grows in the presence of 2-chloro-phenol and 2-methyl, 4-chlorophenol (which are also degraded) and in the presence of 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, which are either degraded or not, as in the case of 4-nitrophenol. The kinetics of both growth and of aromatic catabolism is suggestive of inductive phenomena for key metabolic enzymes.

Culture Media↗
PubMed1994

[Assessment of genotoxic activity of azo dye thiadiazole derivatives with the help of a structural chromosome aberration test].

The genotoxic activity of 2-methyl aminothiadiazole and azo dyes series of azo thiadiazole-1,3,4 was assessed using chromosome aberration in vivo and in vitro. The test in vivo was performed on mice bone marrow cells and in vitro on human blood lymphocytes. Derivatives of 2-naphthol, p-chlorophenol, pyro-catechin, resorcin and gamma resorcin acid were tested. The study did not reveal any toxic effect of azo dies in doses used in the test. Their use in the synthesis of more complex substances can be recommended.

Animals↗
PubMedDate not supplied

Pharmacokinetic study of p-chloronitrobenzene in rat.

The pharmacokinetics of p-chloronitrobenzene (p-CNB) was evaluated in rats to propose an index for monitoring p-CNB exposure of humans exposed to it. After a single dose of 30, 100, or 333 mg/kg body weight, p-CNB was administered intraperitoneally to male Sprague-Dawley rats; blood and urine were collected periodically. p-CNB in plasma and its five major metabolites--2-chloro-5-nitrophenol, N-acetyl-S-(4-nitrophenyl)-L-cysteine,2,4-dichloroaniline,p-chloroanilin e, and 2-amino-5-chlorophenol--in urine were measured by reversed-phase HPLC methods. Pharmacokinetics was evaluated by moment analysis and compartment model analysis of the p-CNB concentration in plasma vs. time curves and of the urinary excretion rate of its metabolites vs. time curves. Urinary excretion was considered to be the most important pathway for disappearance of p-CNB, because the fraction of p-CNB metabolites excreted in urine was ca.2/3 of the dose level. N-Acetyl-S-(4-nitrophenyl)-L-cysteine was the most abundant urinary metabolite of p-CNB and comprised ca.1/2 of the total amount of the five metabolites excreted into the urine. The urinary excretion of N-acetyl-S-(4-nitrophenyl)-L-cysteine was considered to be proportional to the dose of p-CNB over a wide range of doses, because the process of metabolism of p-CNB to N-acetyl-S-(4-nitrophenyl)-L-cysteine was linear in the dose range studied. Consequently, urinary N-acetyl-S-(4-nitrophenyl)-L-cysteine was considered to be suitable as an index for monitoring p-CNB exposure.

Animals↗
PubMed1996

Mechanism mediating basolateral transport of 2,4-dichlorophenoxyacetic acid in rat kidney.

The organic anions, p-aminohippurate (PAH) and fluorescein, are transported across the basolateral membrane of the renal proximal tubule in exchange for intracellular alpha-ketoglutarate (alpha KG), a mechanism indirectly coupled to sodium via Na+/alpha KG cotransport. To determine whether this mechanism mediates the basolateral transport of other organic anions, transport of the herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D), was examined in rat renal cortical slices and basolateral membrane vesicles. In slices, uptake of 2,4-D increased steadily over time, approaching steady-state tissue/medium ratios of approximately 8 after 60 min. Probenecid, PAH and chlorophenol red inhibited steady-state uptake of 2,4-D. Accumulation of 10 microM 2,4-D was stimulated 2-fold by 60 microM glutarate; other dicarboxylic acids failed to stimulate uptake. In the presence of sodium, the addition of 5 mM LiCl or 2 mM ouabain to the bathing medium abolished glutarate stimulation. Removal of sodium from the bathing medium reversibly inhibited uptake as much as 75%. Furthermore, PAH inhibited 2,4-D uptake by slices in a dose-dependent manner, and increasing the external 2,4-D concentration decreased the inhibitory potency of PAH. In basolateral membrane vesicles, unlabeled 2,4-D inhibited sodium glutarate-coupled uptake of 3H-labeled PAH and 2,4-D in a concentration-dependent manner. Moreover, concentrative uptake of 2,4-D into vesicles could be driven by an outwardly directed gradient of glutarate or alpha KG that was generated by lithium-sensitive Na+/dicarboxylate cotransport or imposed experimentally. An outwardly directed gradient of unlabeled 2,4-D or PAH also stimulated uptake of 2,4-D. Based on these data, basolateral accumulation of 2,4-D by the renal proximal tubule is mediated by 2,4-D/alpha KG exchange, a mechanism energetically coupled to Na+/alpha KG cotransport and shared with PAH.

2,4-Dichlorophenoxyacetic Acid↗
PubMedDate not supplied

TCDD residues in fish and shellfish from U.S. waterways.

TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) in the edible portion of fish and shellfish from various U.S. waterways has been monitored since 1979. Analytical results for the period 1979-1994 are reported. Extracts obtained after column chromatographic and liquid chromatographic cleanup were examined by electron capture detection-gas chromatography (GC), and final quantitation and confirmation were performed by GC/mass spectrometry with multiple ion detection. Analyses of 1623 test samples indicated that TCDD residues in fish and shellfish were not widespread but rather were localized in areas near waste sites, chlorophenol manufacturers, and pulp and paper mills. Analytical results indicated that levels in aquatic species from these sites have been declining steadily. No TCDD (limit of detection and confirmation, 1-2 ppt) has been found in recent years in aquatic species from most Atlantic, Pacific, and Gulf of Mexico sites and Great Lakes other than Lake Ontario and Saginaw Bay (Lake Huron).

Animals↗
PubMed1998

Environmental and occupational aspects on the etiology of non-Hodgkin's lymphoma.

Immunosuppression, possibly in combination with viruses, could be a main etiologic mechanism for non-Hodgkin's lymphoma (NHL). Chemicals such as phenoxyacetic acids, chlorophenols, dioxins, organic solvents, polychlorinated biphenyls, chlordane, and immunosuppressive drugs have been associated with this disease. Also UV light and blood transfusion have been postulated to be risk factors. Conclusive evidence of a causal association with NHL is not established for all of these exposures, but experimental evidence and clinical observations indicate that all these exposures have in common that they may impair the immune system. Furthermore, acquired and congenital immune deficiency as well as autoimmune disorders increase the risk for NHL. In view of currently available evidence, the first priority for reducing morbidity due to NHL might be to take action against adverse chemical exposures as a measure that is more easily achievable than any other kind of prevention.

Carcinogens↗
PubMed1998

Contact chemostimuli in the mating behaviour of the cattle tick, Boophilus microplus.

Mating of the cattle tick Boophilus microplus is mediated by chemical stimuli on the cuticle of females. Males are arrested on the dorsum of females attached to the host, frequently sample the substrate, and then tip-over to the ventrally located gonopore. These behaviours are also observed in vitro when males are placed on a small glass bead treated with a female extract. Time spent and tip-over by male ticks on dummies is used in an assay to test the behavioural significance of fractions of the extract. TLC separation yields one apolar fraction that arrests males, though much less so than the whole extract, but lost tip-over behaviour. This apolar fraction contains a series of cholesteryl esters that, when tested individually, show no arrestment activity at levels present in the extract but, when combined, are as active as the fraction. When a small silica column is used for fractionation, all biological activity is reproduced after recombining the fractions. In addition to the early eluting apolar fraction containing cholesteryl esters, a set of highly active more polar fractions is isolated. Electrophysiological recordings from gustatory sensilla on the pedipalps of male B. microplus, which are regularly brought into contact with the cuticle of the female during mating, provide evidence for receptors in two of them responding to the whole extract and to the behaviourally active polar fractions. Mating behaviour involving arrestment and tip-over is clearly initiated by a mixture of chemical stimuli, and tip-over behaviour is associated with the more polar material.

Animals↗
PubMed2000

Degradation of 2,4,6-trichlorophenol via chlorohydroxyquinol in Ralstonia eutropha JMP134 and JMP222.

The aim of this work was to study the catabolic pathway of the pollutant 2,4,6-trichlorophenol in Ralstonia eutropha JMP134. 2,6-dichlorohydroquinone was detected as transient intermediate. Enzymatic transformations of 6-chlorohydroxyquinol to 2-chloromaleylacetate, and of this compound to maleylacetate were detected in crude extracts. Therefore, the degradation of 2,4,6-trichlorophenol proceeded through an hydroxyquinol pathway, different from the other chloroaromatic pathways reported in this strain. The same results were observed in two other 2,4,6-trichlorophenol degrading strains: R. eutropha JMP222, a derivative of strain JMP134 lacking the chlorocatechol catabolism-encoding pJP4 plasmid, and a river isolate, Ralstonia sp. PZK.

Biodegradation, Environmental↗
PubMed2001

Synthesis of the beta-D-glucuronides of 2,3-, 3,4-, and 2,6-dichlorophenol.

The beta-D-glucuronides of 2,3-, 3,4-, and 2,6-dichlorophenol (1-3) were prepared by a modified Koenigs-Knorr synthesis. As the alkaline hydrolysis of perpivaloylated methyl (2,3-dichlorophenyl)-glucuronate 1a led to a dehydrated glucuronide, the preparation of peracetylated methyl dichlorophenylglucuronates with subsequent cleavage of the ester bindings under mild conditions was preferred.

Butanols↗
PubMed1988

Validity and reliability of a method for retrospective evaluation of chlorophenate exposure in the lumber industry.

This paper describes the validity and reliability of a method to retrospectively assess exposure to antisapstain agents used in sawmills (chlorophenates). The method is based on experienced workers' estimates of exposure for each job title at the sawmill where they work. At a pilot mill, 10 randomly selected workers estimated the frequency and duration of exposures to chlorophenates for all 59 job titles. The reliability of their mean exposure estimates was very high, with an intraclass correlation coefficient for all raters of 0.91 (based on a calculated index of exposure). To assess validity, urinary chlorophenate levels were measured for 86% of the workers at the mill during the summer and/or fall, and compared to experienced workers' estimates of exposure. The correlation between workers' exposure estimates and the urinary chlorophenate levels for each job title were consistently above 0.65 for all analyses and greater than 0.72 when summer and fall urine sample results were averaged. The evidence indicates that the validity and reliability of worker exposure estimates are high enough to justify investigation of the method's generalizability to other sawmills.

Chlorophenols↗
PubMed1990

Chloracne associated with employment in the production of pentachlorophenol.

To evaluate the association between exposure to pentachlorophenol (PCP) and the occurrence of chloracne, we studied the medical and personnel records for individuals employed in the manufacturing of PCP. Forty-seven cases of chloracne were identified among 648 workers (7.0%) assigned to PCP production at a single plant between 1953 and 1978. The annual incidence rate varied considerably, ranging from 0 (in 1953) to 1.46 (in 1978). No linear trend in the risk of chloracne was observed with the duration of employment in the pentachlorophenol department. Workers with a documented episode of direct skin contact with PCP had a significantly increased risk of chloracne compared with workers who did not have a documented episode of direct skin contact (cumulative incidence ratio = 4.6; 95% confidence interval 2.6-8.1). Our results confirm that chloracne is associated with exposure to PCP contaminated with hexachlorinated, heptachlorinated, and octachlorinated dibenzo-p-dioxins and dibenzofurans.

Acne Vulgaris↗