Enhancing activity of rat tissue extracts for induction of lambda prophage by L-azaserine

We studied the effect of rat tissue extracts on induction of lambda prophage in Escherichia coli (lambda) by L-azaserine. Hepatic and pancreatic extracts, primarily the cytosolic fraction, markedly increased the rate of induction. Hepatic extracts from lipotrope-deficient rats were somewhat more active than extracts from normal rats. The enhancing activity in normal rat hepatic cytosol was partially characterized. It reduced by about one-half the dose of azaserine required for a given purpose. The enhancement was increased by preincubating the bacterial cells with cytosol; cells retained the effect after cytosol was removed. Enhancing activity was inhibited strongly by the amino acids phenylalanine, tryptophan, and tyrosine; to lesser extents by leucine, methionine, and serine; and not at all by proline or glutamine. It was eliminated by dialysis of the cytosol and reduced by omission of nicotinamide adenine dinucleotide phosphate (NADP) from the reaction mixture. Heating the cytosol to 60 degrees C or 80 degrees C or varying the pH of the reaction mixture from 6 to 8 had no significant effect. Treating the cytosol with trypsin appeared to release an inhibitor of the activity. Glutathione, cysteine, and beta-mercaptoethanol also enhanced lambda induction by azaserine, but the cytosolic activity was not affected by the thiol-inactivating compound diethylmaleate (DEM). The results suggest that factors in cytosol interact with bacterial cells to facilitate transport of azaserine into the cells, primarily through the aromatic amino acid transport system. A small molecule, not a free thiol compound, appears to be involved. It may serve to establish reducing conditions protective for azaserine, the probable mechanism of action of sulfhydryl compounds.     

Accelerated healing of full-thickness burns by the use of high-voltage pulsed galvanic stimulation in the pig

An experimental study was designed using domestic pigs to evaluate the effect of high-voltage pulsed galvanic stimulation (HVPGS) on the rate of healing of full-thickness thermal burns. Twenty animals were used in the study; each one received two standardized burns over the paravertebral region. In half of the animals, HVPGS was performed daily for the study period. One of the burn wounds in each pig was used to evaluate wound contraction by measuring the wound surface weekly for four weeks. The second burn wound had weekly tissue biopsies to evaluate fibroblast population. The data showed a significantly faster rate of wound contraction (p less than 0.001) and a higher fibroblast response (p less than 0.001) in the HVPGS group when compared with controls.     

Tensile strength of orthodontic brackets bonded directly to fluorotic and nonfluorotic teeth: an in vitro comparative study.

Information related to bonding of orthodontic brackets to fluorotic teeth is scanty. The purpose of this study was to compare, in vitro, the tensile bond strength and the bond failure site of brackets bonded directly to fluorotic and nonfluorotic teeth. The etching patterns were also evaluated. The study involved 26 teeth classified as score 3 and 4, and 26 as score 0 with the Thylstrup and Fejerskov's (TF) fluorosis index. In addition to the clinical classification, difference in the concentration of fluoride in the teeth was verified by acid etching. Brackets were bonded with a composite resin after etching the enamel surface with 40% phosphoric acid for 60 seconds. Tensile bond strength was determined with an Instron testing machine. The bond failure site was assessed by the percentage of residue cement on the tooth surface after debonding and the etching pattern by SEM. The mean concentration of fluoride was 2888.5 ppm (SD 1081.7) in the fluorotic teeth and 1227.1 ppm (SD 526.3) in the nonfluorotic teeth. The mean bond strength was 7.8 N/mm2 (SD 1.47) for the fluorotic teeth and 8.6 N/mm2 (SD 2.19) for the nonfluorotic teeth. The difference between the means for bond strength was not statistically significant (p greater than 0.05). Bond failure site was primarily at the bracket-adhesive interface. The mean percentage of adhesive on the enamel surface after debonding was 70% (SD 25.90) for the fluorotic teeth and 75% (SD 24.66) for nonfluorotic teeth. The difference in the means was not statistically significant (p greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Multifocal malignant melanoma of the esophagus.

We have described a case of primary melanoma of the esophagus in an asymptomatic patient. The tumor presented as a multinodular filling defect on a routine barium swallow. The distal esophagus and a proximal portion of the stomach were resected. The patient died ten days postoperatively of Klebsiella sepsis. Grossly, the surgical specimen showed multiple polypoid tumors which arose from separate pigmented areas shown microscopically to be melanoma in situ. By electron microscopy, the tumor cells contained numerous melanosomes in various stages of melanization. Primitive hemidesmosomes were found where a basal lamina was present. Better developed desmosomes interconnected the melanocytes.     

The influence of several factors that intervene in hemodialysis on serum levels of triglycerides and free fatty acids.

The effect of the administration of heparin and glucose, in doses and sequence similar to those of hemodialysis, on serum free fatty acids and triglycerides, was studied in eight patients with chronic renal failure who had not undergone hemodialysis. The results are compared with the action exerted by hemodialysis on the same parameters. During hemodialysis, the values of triglycerides are not significantly different from those obtained at similar intervals after the administration of glucose and/or heparin, with the exception that the values obtained five hours after beginning hemodialysis are lower than those obtained five hours after the administration of glucose (P less than 0.005). The levels of free fatty acids obtained during hemodialysis are higher (P less than 0.005) than those found during the other tests. The possible origin of these high fatty acid values is discussed, and the possibility that they originate from the acetate in the dialysis liquid is suggested.     

Individual risk of abdominal disease in patients with stages I and II supradiaphragmatic Hodgkin's disease. A rule index based on 341 laparotomized patients

A multivariate analysis of the prognostic factors for clinical Stages I and II supradiaphragmatic Hodgkin's disease was carried out with a logistic regression model in 341 patients. The proportion of patients with positive staging laparotomy was greater in males, in individuals with several sites involved, mixed cellularity (MC) or lymphocyte depletion (LD) histologic types, systemic symptoms, or in patients with lower cervical involvement and higher erythrocyte sedimentation rate (ESR), serum copper, and LDH levels. Histology, presence of systemic symptoms (fever and sweats), and number of involved nodal regions were independent predictors of positive laparotomy. Mediastinal involvement is correlated to a significantly lower risk of positive laparotomy. Based on these observations, the individual risk for each patient of occult abdominal disease has been defined.     

Four-day continuous infusion of cisplatin and 5-fluorouracil in head and neck cancer

A combination of cisplatin and 5-fluorouracil, both administered 4 days continuously as infusion, was assessed in advanced head and neck cancer. Of the 37 patients studied, there were 15 complete and 17 partial responses (40.5% and 45.9%, respectively). Survival is 79.1% at 22 months. None of the patients in complete response has relapsed. In general toxic effects were moderate. Given as initial treatment, the regimen is effective and of considerable use in this type of patient.     

Intrahepatic bile duct and portal vein anatomy revisited

Seventeen normal cadaver livers were studied to assess the anatomic relationship of bile ducts to portal veins. The common bile duct, main portal vein, and hepatic artery were cannulated and injected with air, dilute contrast medium, and mineral oil, respectively. The livers were placed in anatomic position and examined with computed tomography. In the lateral segment of the left hepatic lobe, the bile ducts were anterior to the portal vein in seven cases, posterior in seven, and tortuous (ie, both anterior and posterior) in three. In the medial segment of the left lobe, the bile ducts were anterior in four cases, posterior in four, tortuous in three, and not seen in six. In the right lobe, the bile ducts were anterior in nine cases, posterior in five, tortuous in one, and not seen in two. In the porta hepatis, the bile ducts were anterior in ten cases, posterior in one, tortuous in five, and not seen in one. Histologic findings confirmed the anterior and posterior location of the bile ducts relative to the portal veins. These findings contradict the commonly held view of intrahepatic bile ducts being anterior to the portal vein and are clinically significant for techniques such as bile duct drainage.