The effect of a single administration of aromatic hydrocarbons (AHCs) on the metabolic activity responsible for the biotransformation of dichloromethane (DCM) to carbon monoxide (CO) was investigated using adult female rats. In rats treated orally with benzene (1.5 ml kg-1), toluene (2.0 ml kg-1) or m-xylene (2.0 ml kg-1) 16-24 h prior to DCM (3 mmol kg-1, i.p.), the carboxyhaemoglobin (COHb) level was elevated, reaching peaks in blood at 21%, 16% and 23%, respectively, compared to the peak of ca. 10% in rats treated with DCM only. Their effects on COHb generation were highly dependent on the time interval between each AHC and DCM treatment, since an early administration of m-xylene or toluene decreased the COHb elevation. The half-life of DCM in blood was shortened significantly, indicating that the metabolic degradation of DCM was enhanced by the AHCs. Disulfiram (3.4 mmol kg-1, p.o.) blocked COHb elevation completely, suggesting that the metabolic conversion of DCM to CO is mediated by cytochrome P-450 2E1 (P4502E1). Corresponding increases in the concentration and half-life of DCM in blood were also observed. A single administration of the AHCs did not alter the hepatic glutathione level, suggesting that the increase in DCM-induced COHb elevation was not due to hepatic glutathione depletion. In vitro studies showed that the hepatic microsomal metabolism of nitrosodimethylamine and p-nitrophenol was significantly increased by a single dose of each AHC. Total cytochrome P-450 content and p-nitroanisole demethylase activity were also increased; however, only toluene and m-xylene were effective inducers for aminopyrine N-demethylase. Therefore, benzene appears to be a selective inducer for P4502E1 compared to other alkylbenzenes. The results indicate that even a single dose of benzene, toluene or m-xylene may induce the activity of P4502E1 significantly, which is responsible for the increased generation of COHb from DCM, as demonstrated in the present study.

Administration, Oral↗

PubMedDate not supplied

Cloning, characterization and phenotypic expression in Escherichia coli of catF, which encodes the catalytic subunit of catalase isozyme CatF of Pseudomonas syringae.

The phytophathogenic, gram-negative bacterium Pseudomonas syringae pv. syringae 61 contains three isozymes of catalase (EC 1.11.1.6), which have been proposed to play a role in the bacterium's responses to various environmental stresses. To study the role of individual isozymes, the gene coding for the catalytic subunit of one catalase isozyme was cloned from a cosmid library hosted in Escherichia coli DH5 alpha by using a designed catalase-specific DNA probe for the screening. One out of four clones with a catalase-positive genotype was subcloned and a pUC19-based 2.7 x 10(3)-base (2.7-kb) insert subclone, pMK3E5, was used to transform catalase-deficient E. coli strain UM255 (HPI-, HPII-). The transformants contained a single isozyme of catalase that had electrophoretic and enzymic properties similar to catalase isozyme CatF from P. syringae pv. syringae 61. Analysis of the sequenced 2.7-kb insert DNA revealed six putative open-reading frames (ORF). The 1542-base-pair DNA sequence of ORF2, called catF, encodes a peptide of 513 amino acid residues with a calculated molecular mass of 66.6 kDa. The amino acid sequence deduced from catF had homology to the primary structure of true catalases from mammals, plants, yeasts and bacteria. The activity of the recombinant catalase was inhibited by 3-amino-1,2,4-triazole and azide and stimulated by chloramphenicol. The N terminus contained a signal sequence of 26 amino acids necessary for secretion into the periplasm, a so-far unique property of Pseudomonas catalases.

Amino Acid Sequence↗

PubMedDate not supplied

Subphrenic bronchogenic cyst mimicking a juxtahepatic solid lesion.

Most bronchogenic cysts occur in the mediastinum. However, they may be found near any organ derived from the embryonic foregut, even in the extrathoracic region. We report a case of subphrenic bronchogenic cyst that was initially confused with a solid lesion because of its unusual location and atypical appearance on ultrasonography, computed tomography, and magnetic resonance imaging.

Bronchogenic Cyst↗

PubMedDate not supplied

Effect of carbon monoxide inhalation exposure in mice on drug metabolism in vivo.

Experiments were undertaken to evaluate the action of carbon monoxide (CO) on the mixed-function oxidase (MFO) system in vivo. Mice were exposed to 500 ppm CO for 8 h per day in an inhalation chamber under dynamic airflow conditions. Hexobarbital (150 mg/kg, i.p.), zoxazolamine (150 mg/kg, i.p.) or ethanol (2 mg/g, i.p.) was given to each group of mice during CO exposure and disappearance of the drug from blood or brain was determined while CO exposure continued. The experiments were repeated with different groups of animals which were exposed to CO for 3 or 5 days. Hexobarbital and ethanol metabolism were not affected by CO following either one day exposure or repeated exposure. There was no statistically significant difference in the brain level of zoxazolamine in animals exposed to CO when compared to control. These studies indicate that in vivo metabolism of hexobarbital, zoxazolamine and ethanol in mice is not affected by exposure to 500 ppm CO under the conditions employed in the present study.

Animals↗

PubMedDate not supplied

Structurally related nucleotides as selective agonists and antagonists at P2Y1 receptors.

The P2Y1 receptor responds to adenine nucleotides and is present in platelets, heart, smooth muscles prostate, ovary, and brain. A selective antagonist may be useful as an antithrombotic agent. We have analyzed the binding site of this G protein-coupled receptor using ligand design, site-directed mutagenesis, and homology modeling based on rhodopsin. We have designed and synthesized a series of deoxyadenosine 3',5'-bisphosphate derivatives that act as antagonists, or, in some cases with small structural changes, as agonists or partial agonists. The 2-position accommodates Cl or thioethers, whereas the N6-position is limited to Me or Et. 2'-Substitution with OH or OMe increases agonist efficacy over 2'-H. Using molecular modeling of the binding site, the oxygen atoms of the ribose moiety were predicted to be non-essential, i.e. no specific H-bonds with the receptor protein appear in the model. We have, therefore, substituted this moiety with carbocylics, smaller and larger rings, conformationally constrained rings, and acyclics, with retention of affinity for the receptor. With simplified pharmacophores we are exploring the steric and electronic requirements of the receptor binding site, and the structural basis of receptor activation.

Binding Sites↗

PubMedDate not supplied

Gene expression analysis in cucumber leaves primed by root colonization with Pseudomonas chlororaphis O6 upon challenge-inoculation with Corynespora cassiicola.

Root colonization by Pseudomonas chlororaphis O6, a non-pathogenic rhizobacterium, induced systemic resistance in cucumber against target leaf spot caused by Corynespora cassiicola. A cDNA library was constructed using mRNA extracted from cucumber leaves 12 h after inoculation with C. cassiicola, using plants colonized by O6. To identify genes involved in O6-mediated induced systemic resistance (ISR), we employed a subtractive hybridization method using mRNAs extracted from pathogen-challenged cucumber leaves of plants lacking colonization. Differential screening of the cDNA library led to the isolation of six distinct genes encoding a GTP binding protein, a 60S ribosomal protein, a hypersensitive-induced reaction protein, a ubiquitin extension protein, a pyridine nucleotide-disulfide oxidoreductase, and a signal recognition particle receptor. Expression of these genes was not induced by O6 colonization alone. Rather, transcript accumulation of these genes increased significantly faster and stronger in the O6 colonized than in non-colonized plants after challenge infection. Therefore, O6-mediated ISR may be associated with an enhanced capacity for the rapid and effective activation of cellular defence responses after challenge inoculation.

Ascomycota↗

PubMedDate not supplied

Ribose modified nucleosides and nucleotides as ligands for purine receptors.

Molecular modeling of receptors for adenosine and nucleotide (P2) receptors with docked ligand, based on mutagenesis, was carried out. Adenosine 3',5'-bisphosphate derivatives act as selective P2Y1 antagonists/partial agonists. The ribose moiety was replaced with carbocyclics, smaller and larger rings, conformationally constrained rings, and acyclics, producing compounds that retained receptor affinity. Conformational constraints were built into the ribose rings of nucleoside and nucleotide ligands using the methanocarba approach, i.e. fused cyclopropane and cyclopentane rings in place of ribose, suggesting a preference for the Northern (N) conformation among ligands for P2Y1 and A1 and A3ARs.

Animals↗

PubMedDate not supplied

Computed tomography of renal tuberculosis and its pathological correlates.

Computed tomographic studies of eight patients with proven renal tuberculosis demonstrated a spectrum of findings related to the extent and the severity of kidney involvement. In early or focal disease, obstruction of a single major calyx or a group of minor calyces was noted (four cases) with no excretion of contrast material into the affected calyces (three cases) and cortical thinning. Tuberculosis of the renal pelvis (five cases) was manifested by either pelvic dilatation secondary to ureteropelvic junction obstruction (three patients) or diffuse pelvic contraction (two patients). In far advanced disease (four cases) the kidneys were small and exhibited atrophy with replacement of parenchyma by one or more low density areas. Calcifications (37.5%) were identified in the parenchyma and within the calyces. Computed tomography may provide the first clue in suggesting the inflammatory nature of a renal mass and excluding a neoplastic process. Computed tomography is also of value in determining the full extent of extrarenal involvement and the amount of residual functioning parenchyma, both of which are critical in proper treatment planning.

Adult↗

PubMedDate not supplied

Immunohistochemical studies on the localization of cancer associated antigens DU-PAN-2 and CA19-9 in carcinomas of the digestive tract.

The immunohistochemical localization of DU-PAN-2 antigen and CA19-9 antigen in carcinomas of the digestive tract was studied using an immunoperoxidase technique. Staining for DU-PAN-2 antigen and CA19-9 antigen was observed in 104 (79%) and 96 (73%) of 131 carcinomas of the digestive tract, respectively. Diffuse staining (more than 20% of carcinoma cell stained) for DU-PAN-2 was detected in 14 of 21 (67%) pancreatic carcinomas and 11 of 19 (58%) carcinomas of the biliary tract (including cholangiocarcinoma). Diffuse staining for CA19-9 was detected in 15 (71%) of pancreatic carcinomas and nine (47%) of the carcinomas of the biliary tract. In colon carcinomas, no diffuse staining for DU-PAN-2 was observed, whereas diffuse staining for CA19-9 was found in 41%. There was a positive correlation between the differentiation degree (or grade) of the adenocarcinomas of the colon and the expression of CA19-9, but not that of DU-PAN-2. These immunohistochemical studies showed that DU-PAN-2 antigen is expressed diffusely in most cases of adenocarcinoma of the pancreas and biliary tract and is more specific for adenocarcinomas of the pancreas and biliary tract than CA19-9.

Adenocarcinoma↗

PubMedDate not supplied

Clear cell papulosis: case report and literature review.

Clear cell papulosis is a newly described skin disease characterized by multiple white papules. Histopathologically, diagnostic clear cells were seen among the basal cells of the epidermis. We report clear cell papulosis on the lumbar area and buttocks of a 1-year-old girl.

Diagnosis, Differential↗

PubMedDate not supplied

Efficacy of prophylactic ondansetron in a patient-controlled analgesia environment.

We conducted a prospective, randomized, double-blind, placebo-controlled trial to examine the efficacy of prophylactic ondansetron on post-operative nausea and vomiting (PONV) during opioid patient-controlled analgesia (PCA). In total, 374 patients using opioid PCA, but otherwise considered to be low risk for PONV, were randomly allocated to ondansetron (4 mg given intravenously and 16 mg added into the PCA pump) or saline (control group). PONV was evaluated in terms of nausea graded on a visual analogue scale, and the number of patients who experienced emetic episodes or needed rescue anti-emetics in the 48-h post-operative period. Patient satisfaction for PCA was scored at the end of the evaluation period. The only difference between the two groups was the higher number of headaches in the ondansetron group. In patients using opioid PCA, but with no other high risk factors for PONV, prophylactic ondansetron does not have any clinical benefit.

Aged↗