An in vitro investigation into the wear effects of unglazed, glazed, and polished porcelain on human enamel

A pBR322-based vector, pCI195, containing a 4.2-kb region of the conjugative transposon Tn919 was used as a vector for gene cloning in Clostridium difficile. The plasmid was found to integrate into the chromosome of a Bacillus subtilis strain that contained Tn916 delta E. Southern blot analysis of the recombinant demonstrated that pCI195 had inserted into Tn916 delta E by a recombination event. The transposon::plasmid structure could be transferred, by filter mating, from B. subtilis to C. difficile (at a frequency of 10(-8) per donor), where it entered the chromosome at a specific site. Segregation of plasmid and transposon markers was observed on transfer, although the Tn916 delta E::pCI195 was stably maintained in C. difficile. To demonstrate that pCI195 could be used for gene cloning in C. difficile, a 1.1-kb fragment of the C. difficile toxin B gene was cloned into pCI195 to generate pPPM100. Tn916 delta E::pPPM100 was transferred into a nontoxigenic C. difficile strain by filter mating, where it entered the genome at a specific site. pCI195 should be useful as a general cloning vector for C. difficile, as the transposon::plasmid structure could be transferred to different C. difficile strains. This is the first report of gene cloning in C. difficile.     

Potential application of p53 as an intermediate biomarker in Barrett's esophagus

Diagnosis of the neoplastic progression in Barrett's esophagus using the histologic classification of dysplasia is frequently difficult. The tumor suppressor protein p53, when mutated, confers a promoter effect on cell growth. The purpose of this study was to evaluate the applicability of p53 as an intermediate biomarker of malignancy in Barrett's esophagus. Archival analysis of 100 biopsy specimens of Barrett's esophagus and 10 esophageal adenocarcinomas were compared with 35 chronic esophagitis biopsy specimens. Immunocytochemistry using an anti-p53 monoclonal antibody was performed and elevated immunoreactivity quantitated microscopically. Data were analyzed using a logistic regression model. Significant p53 immunoreactivity occurred as follows: chronic esophagitis (0%), Barrett's esophagus without dysplasia (10%), with low-grade dysplasia (60%), with high-grade dysplasia (100%), and adenocarcinoma (70%). All cases of Barrett's esophagus were significantly immunoreactive when compared with the chronic esophagitis cases (p = 0.001). There was an increase in p53 immunoreactivity as the histologic classification progressed toward adenocarcinoma (p = 0.001). Progression to high-grade dysplasia may be predicted based on p53 immunoreactivity. These findings suggest a role for p53 as an intermediate biomarker in Barrett's esophagus.     

An anaesthetic drug error: minimizing the risk

Goldfish cells (RBCF-1) cultured at different cell densities were harvested and their photorepair (PR) abilities were examined in terms of survival. Photorepair ability gradually increased during the phase of logarithmic growth, reaching a maximum in cells at the confluent state. This enhancement of PR ability disappeared 12 h after replating of cells in fresh medium. A number of growth-inhibiting treatments (serum depletion, UVC, hydroxyurea [HU], change in incubation temperature) were tested for their ability to induce PR. The treatment of cells with HU and serum depletion induced PR while the other treatments did not. The increase in the ability to perform PR after treatment with HU or serum depletion returned to normal levels more rapidly than that after fluorescent light treatment.     

Evaluation of the biliary tree: a comparison of percutaneous transhepatic cholangiography and ultrasonography

After we examined 45 patients with jaundice, using both percutaneous transhepatic cholangiography and ultrasonography, our results suggest that ultrasound is useful as an early screening procedure in evaluating patients with jaundice.     

Steroid-responsive encephalomyelitis in childhood

The syndrome of parainfectious encephalomyelitis evolves from an antecedent infection. Several etiologic agents have been associated with this complication, although the pathogenesis in each instance may prove to be more uniform. Considerable evidence suggests that the syndrome is mediated immunologically. The seven cases reported here were clinically similar, although the infectious etiologies were diverse. Leptospirosis antedated the neurologic syndrome in two cases, and a "viral" illness preceded the other five cases. The evolution of the syndrome was slowly progressive in each case, and six patients had prominent involvement of rhombencephalic structures. The progressive course was reversed rapidly with eventual full recovery in each instance after initiation of corticosteroid therapy. Our experience with these cases coupled with a review of the literature suggests that corticosteroid therapy should be considered in the subacute or chronic cases of parainfectious encephalomyelitis.     

Protein accumulation in cerebrospinal fluid during -90 degrees head-down tilt in rabbit

Plasma proteins are only somewhat larger than the intercellular spaces of the cerebral microvessels that constitute the blood-brain barrier or of the choroid plexus villi that elaborate cerebrospinal fluid (CSF). We hypothesized that the integrity of these barriers in anesthetized rabbits might be compromised during head-down tilt (HDT). Plasma protein and osmolality, hematocrit, and CSF protein concentration were compared in rabbits exposed to 1 h of HDT (n = 20) and prone rabbits (n = 10). In addition, the concentration of trypan blue dye, injected intravenously at the end of HDT or the prone position, was measured in brain homogenate. Finally, arterial blood pressure was measured via a catheterized carotid artery. HDT disrupted the barrier between blood and CSF, as indicated by a significantly (P < 0.01) greater brain trypan blue concentration in the HDT rabbits [172.2 +/- 14.4 (SD) micrograms/g dry wt] than in the prone rabbits (29.8 +/- 4.4 micrograms/g dry wt). Moreover CSF protein 5 min after HDT onset was significantly increased compared with control in HDT rabbits (54.6 +/- 1.9 vs. 81.4 +/- 5.2 mg/dl; n = 8) but not in prone rabbits (55.6 +/- 2.7 vs. 57.2 +/- 5.0 mg/dl; n = 6). Changes in the plasma protein-to-hematocrit ratio in the HDT animals, but not in the prone animals, were also compatible with a loss of fluid from the vascular compartment.(ABSTRACT TRUNCATED AT 250 WORDS)