An eukaryotic RuvB-like protein (RUVBL1) essential for growth

A human protein (RUVBL1), consisting of 456 amino acids (50 kDa) and highly homologous to RuvB, was identified by using the 14-kDa subunit of replication protein A (hsRPA3) as bait in a yeast two-hybrid system. RuvB is a bacterial protein involved in genetic recombination that bears structural similarity to subunits of the RF-C clamp loader family of proteins. Fluorescence in situ hybridization analysis demonstrated that the RUVBL1 gene is located at 3q21, a region with frequent rearrangements in different types of leukemia and solid tumors. RUVBL1 co-immunoprecipitated with at least three other unidentified cellular proteins and was detected in the RNA polymerase II holoenzyme complex purified over multiple chromatographic steps. In addition, two yeast homologs, scRUVBL1 and scRUVBL2 with 70 and 42% identity to RUVBL1, respectively, were revealed by screening the complete Saccharomyces cerevisiae genome sequence. Yeast with a null mutation in scRUVBL1 was nonviable. Thus RUVBL1 is an eukaryotic member of the RuvB/clamp loader family of structurally related proteins from bacteria and eukaryotes that is essential for viability of yeast.     

Transneuronal WGA-HRP: can it demonstrate development of ocular dominance patches and effects of monocular deprivation?

We have attempted to use intraocular injections of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) to label ocular dominance patches in developing layer 4 of cat visual cortex. The cortices of animals killed at 49 days or later showed normal ocular dominance patches similar to those seen in [3H]proline material. Animals killed at 42 days showed some patches, but also showed unsegregated regions. Animals killed younger were difficult to stain and did not have patches. We also examined the ability of the WGA-HRP technique to demonstrate the effects of monocular deprivation (MD). MD for the first 3 months of life produced expansion of the afferents from the nondeprived eye and retraction of the patches from the deprived eye. One week of MD at about 5 weeks of age produced an expansion of the patches innervated by the nondeprived eye, but did not obviously affect the patches innervated by the deprived eye. We conclude that WGA-HRP is useful for examining the effects of long-term MD on ocular dominance patches but not for following the development of segregation. Its advantages over the [3H]proline technique are that it does not require a delay of many weeks before the sections can be examined and is much less expensive.     

Polarcardiographic criteria for myocardial infarction in Chinese men

A biochemical study was performed in two patients submitted to insulin coma therapy. The injection of insulin resulted in a decrease of free and total tryptophan as well as tyrosine in plasma, while NEFA were not influenced by this treatment. The ratio of tryptophan to tyrosine was enhanced. The administration of glucose after insulin provoked an increase of free and total tryptophan. The results support the hypothesis that in man insulin may favor the uptake of tryptophan by the brain, and enhance the synthesis of cerebral serotonin.     

Evaluation of enzyme-linked immunosorbent assay for the determination of polycyclic aromatic hydrocarbons in house dust and residential soil

Two commercially available enzyme-linked immunosorbent assays (ELISA) for total polycyclic aromatic hydrocarbon (PAH) and carcinogenic PAH (C-PAH) were evaluated. The testing procedures were refined for application to screening PAH and C-PAH in house dust and soil samples for human exposure studies. The overall method precision expressed as percent relative standard deviation (%RSD) of triplicate real world dust and soil samples was within +/- 29% (12-29%) for PAH ELISA and +/- 21% (5.9-21%) for C-PAH ELISA. Spike recoveries from real world dust/soil samples were 114 +/- 30% for phenanthrene from PAH ELISA and 120 +/- 8.2% for benzo[a]pyrene from C-PAH ELISA. The overall method accuracy for PAH and C-PAH assays cannot be assessed for multiple PAH components in dust/soil samples (which represent real-world samples), because of the assays' cross reactivities with other PAH components. Over 100 dust/soil samples from 13 North Carolina homes and 22 Arizona homes were analyzed by PAH and C-PAH assays, as well as by the conventional gas chromatography/mass spectrometry (GC/MS) method. Statistical analysis showed that dust/soil PAH data from ELISA and GC/MS methods are significantly different. In general PAH ELISA responses were higher than PAH GC/MS responses. The regression analysis showed that the linear relationship between ELISA and GC/MS measurements is not strong in the combined data. The relationship became stronger for the data from the same type of dust/soil samples. The screening performance of ELISA was evaluated based on the frequency distribution of ELISA and GC/MS data. The results indicated that the ELISA PAH and C-PAH assays cannot be used as a quantitative analytical tool for determining PAH in real-world dust/soil samples. However, the ELISA is an effective screening tool for ranking PAH concentrations in similar types of real world dust/soil samples.     

Effects of gastric mucosal blood flow (GMBF) on the role of adaptive cytoprotection of rat gastric mucosa

It has been reported that ingestion of an ammonium-containing diet produces hyperammonemia without encephalopathy, thus permitting the study of the specific effects of ammonia toxicity. The present study investigated the rat cerebral somatostatinergic system using this experimental model of hyperammonemia. Wistar rats were fed a high ammonia diet prepared by mixing a standard diet with ammonium acetate (20% w/w); in addition, 5 mM of ammonium acetate was added to their water supply. Control rats were fed with a standard diet. The animals were sacrificed at 3, 7 and 15 days of ammonia ingestion. Ammonia levels in blood had increased approximately 3-fold at 7 days of ammonia ingestion. These changes were associated with a significant decrease in the specific binding of somatostatin (SS) to putative receptors sites in the frontoparietal cortex and hippocampus at 7 and 15 days after starting the high ammonia diet. Scatchard analysis shows that the decrease in SS binding resulted from a decrease in the number of available SS receptors rather than a change in receptor affinity. No changes in the somatostatin-like immunoreactivity content (SSLI) were detected in either brain area at the three study times. These results suggest that hyperammonemia alone can affect the rat brain somatostatinergic system. However, the animal model of hyperammonemia used here is insufficient to produce encephalopathy despite the significant increase in serum ammonia.     

A subconjunctival degradable implant for cyclosporine delivery in corneal transplant therapy

The effect of local cyclosporine therapy upon corneal transplant survival was investigated. A high risk rabbit model with vascularized corneas was used to assess the efficacy of subconjunctivally implanted degradable devices for cyclosporine therapy. Animals were divided into four groups, receiving either no therapy, a placebo PLGA device, or drug containing devices implanted either at the time of transplantation or two weeks previous. The mean survival times of animals in the control and placebo groups were statistically equivalent (21 +/- 4 days vs 18 +/- 4 days). Devices containing CsA improved the survival time of grafts. Predosing the animals with CsA improved the survival time to 28 +/- 7 days, and CsA devices implanted at the time of transplantation increased the survival time to 35 +/- 7 days. The improvement in survival times was consistent with the in vitro drug release profiles. No systemic CsA was detected, suggesting that the effect may have been local. Histological assessment indicated that devices were well tolerated.     

The anatomic basis and clinical applications of flaps based on the posterior tibial vessels

The vascular anatomy of the posterior tibial vessels has been studied in 20 legs of 10 cadavers. The number, size and distribution of the direct cutaneous and direct muscle branches of the posterior tibial vessels were recorded. For analysis, the leg was divided into four equal segments, Zone I being the most distal and Zone IV the most proximal. The direct cutaneous branches were found to cluster mainly around Zone II. The direct muscle branches to the soleus and flexor digitorum longus muscles arose chiefly in Zones II and III. Based on this knowledge, we performed fasciocutaneous, island soleus muscle, musculo-fasciocutaneous and flexor digitorum longus muscle flaps based on the posterior tibial vessels in 12 patients. Four were free fasciocutaneous flaps and eight were pedicled flaps. All flaps survived and there were no major complications. Delayed wound healing was encountered in three patients.     

An isometric predictor for maximum acceptable weight of lift for Chinese men

The aim of this study was to examine the practicality of the modified isometric strength tests to predict the maximum acceptable weight of lift (MAWL) of Chinese men. The modified strength tests allow the participant to pull on the load cell in front of the body and to apply force in a functional free posture. Both the modified and the standard strength data of each participant were used as predictors for the MAWLs. The prediction models were constructed and evaluated under task conditions of two lifting ranges, two box sizes, and three lifting frequencies. To realize the effect of modifications, testing posture was recorded and the joint angles were calculated. A stepwise multiple regression analysis indicated that modified composite strength (MCS), chest circumference, and acromial height accounted for 86% to 91% of the variance. Because the strength of the upper extremity body was also recruited in the test, the weak upper extremity strength of the Chinese participants would therefore be better reflected. Evidence for the existence of a close match between MAWL and MCS values, as well as the task conditions for its existence, suggest that a simple isometric strength measure is a good predictor for the MAWL.