Erratum to: Rostrocaudal Dynamics of CSF Biomarkers

Neurochemical Research -     

Targeted gripping reduces shoulder muscle activity and variability

The purpose of this study was to determine if the effect of visually targeted gripping on shoulder muscle activity was maintained with repeated exposures. Eleven healthy males had eight shoulder muscles monitored via surface electromyography while maintaining shoulder elevation at 90° in the scapular plane with and without a 30% grip force. Three non-gripping trials were followed by 15 gripping trials and another 3 non-gripping control trials. Gripping significantly decreased the activity of the anterior deltoid, trapezius, and latissimus dorsi over the exposure of 15 trials. Gripping also reduced variability in all muscles' activity. The changes in shoulder muscle activity are likely in response to forces being transferred through multi-articular muscles spanning from the forearm to the shoulder. Targeted gripping during shoulder elevation resulted in small but significant decreases in muscle activity and reduced variability which supports previous evidence for increased risk of upper extremity disorders in occupational settings.     

Defective galactosylation of serum transferrin in galactosemia

The glycosylation of serum transferrin from galactosemic patients with a deficiency of galactose-1-phosphate uridyl transferase (EC 2. 7.7 12) is abnormal but becomes normal after treatment with a galactose-free diet. To understand the structural and biochemical basis of the abnormal glycosylation, transferrin was purified from the serum of untreated and treated galactosemic patients and normal controls and the N-linked glycans analyzed by HPLC. The glycans from normal transferrin consisted predominantly (86%) of the disialylated biantennary complex type. The glycans from untreated galactosemic patients were more heterogeneous and contained four major truncated glycans in addition to a smaller amount (13%) of the disialylated biantennary complex type. The truncated glycans were deficient in galactose and sialic acid and their structures were consistent with a decrease in galactosyltransferase activity in hepatocytes, the probable cells of origin of the transferrin. This is postulated to be due to direct inhibition of the galactosyltransferase activity by the accumulated galactose-1-phosphate or to an effect on the formation of UDP- galactose, the donor substrate in the reaction. After treatment the proportion of the truncated glycans decreased and the proportion of the disialylated biantennary complex type increased, returning almost but never completely to normal, even after prolonged treatment in some cases. There was no clear relationship between the length of treatment and the normalization of glycosylation and the level of galactose-1- phosphate in red blood cells, the usual parameter for monitoring the treatment of galactosemics. It is suggested that the persistence of abnormally glycosylated proteins may contribute to the long-term complications in galactosemia.      

The activity of deoxyribonucleic acid polymerase in some species of algae

1. The activities of DNA polymerase preparations from the algae Euglena gracilis, Chlamydomonas reinhardtii, Chlorella pyrenoidosa, Anabaena variabilis and Anacystis nidulans were measured. The blue-green algae Anabaena and Anacystis contain a 5-20-fold higher activity of the enzyme than do the green algae. DNA polymerases from the blue-green algae show a pH optimum of 9 and prefer a relatively low Mg(2+) concentration (1-3mm). DNA polymerases from the green algae, however, display a pH optimum between 7.5 and 8.5 and an optimum Mg(2+) concentration of 8mm. With all algae, a higher polymerase activity was obtained with denatured salmon sperm DNA as template than with native DNA. All four deoxyribonucleoside 5'-triphosphates must be present for full activity of the polymerases. 2. With one exception, the deoxyribonuclease activities in the preparations, measured under conditions of the DNA polymerase assay, are low compared with corresponding preparations from Escherichia coli. Chlamydomonas extracts contain a high deoxyribonuclease activity. 3. After purification on columns of DEAE-cellulose, the polymerase activity was linear over a wide range of protein concentrations, except for Chlamydomonas preparations, where the observed deviation from linearity was probably attributable to the high nuclease activity. 4. DNA polymerases from all these algae bind strongly to DNA-cellulose; 6-40-fold purifications of the enzyme were obtained by chromatography on columns of DNA-cellulose. 5. The partially purified polymerases of Euglena and Anacystis are heat-labile but become much more heat-stable when tested in the presence of DNA.     

Synthesis of deoxyribonucleic acid in BHK-21/C13 cells

Newly synthesized (3)H-labelled DNA was extracted from baby hamster kidney cells (BHK-21/C13 cells) and was shown to possess single-stranded properties when examined by column chromatography on benzoylated naphthoylated DEAE-cellulose, hydroxyapatite and methylated albumin on kieselguhr, and by its affinity for nitrocellulose filters. Some of the newly synthesized DNA was shown to be of lower molecular weight than the bulk of the DNA when examined by alkaline sucrose-density-gradient centrifugation. The properties observed were not affected by treatment of the DNA with ribonuclease, Pronase or amylase. The effect of the size of the DNA on its observed properties was examined and is discussed. It is concluded that DNA synthesis in BHK-21/C13 cells proceeds according to the discontinuous-mechanism model in at least one of the strands.     

Fluorescence correlation spectroscopy for ultrasensitive DNA analysis in continuous flow capillary electrophoresis

Continuous flow capillary electrophoresis (CFCE) is non-separations based analytical technique based on the free solution electrophoretic mobility of biological molecules such as DNA, RNA, peptides, and proteins. The electrophoretic mobilities and translational diffusion constants of the analyte molecules are determined using single molecule detection methods, including fluorescence correlation spectroscopy (FCS). CFCE is used to resolve multiple components in a mixture of analytes, measure electrophoretic mobility shifts due to binding interactions, and study the hydrodynamic and electrostatic properties of biological molecules in solution. Often this information is obtained with greater speed and sensitivity than conventational separations-based capillary-zone electrophoresis. This paper will focus on the application of two-beam fluorescence cross-correlation spectroscopy as a versatile detection method for CFCE and explore several applications to the study of the solution properties of single-stranded DNA.     

Histopathological effects of cisplatin,doxorubicin and 5-flurouracil (5-FU) on the liver of male albino rats

Cisplatin, doxorubicin and fluorouracil (5-FU), drugs belonging to different chemical classes, have been extensively used for chemotherapy of various cancers. Despite extensive investigations into their hepatotoxicity, there is very limited information on their effects on the structure and ultra-structure of liver cells in vivo. Here, we demonstrate for the first time, the effects of these three anticancer drugs on rat liver toxicity using both light and electron microscopy. Light microscopic observations revealed that higher doses of cisplatin and doxorubicin caused massive hepatotoxicity compared to 5-FU treatment, including dissolution of hepatic cords, focal inflammation and necrotic tissues. Interestingly, low doses also exhibited abnormal changes, including periportal fibrosis, degeneration of hepatic cords and increased apoptosis. These changes were confirmed at ultrastructural level, including vesiculated rough endoplasmic reticulum and atrophied mitochondria with ill-differentiated cisternae, dense collection of macrophages and lymphocytes as well as fibrocytes with collagenous fibrils manifesting early sign of fibrosis, especially in response to cisplatin and doxorubicin -treatment. Our results provide in vivo evidence, at ultrastructural level, of direct hepatotoxicity caused by cisplatin, doxorubicin and 5-FU at both light and electron microscopi. These results can guide the design of appropriate treatment regimen to reduce the hepatotoxic effects of these anticancer drugs.     

The Ras guanine nucleotide exchange factor RasGRF1 promotes matrix metalloproteinase-3 production in rheumatoid arthritis synovial tissue

Introduction  

Fibroblast-like synoviocytes (FLS) from rheumatoid arthritis (RA) patients share many similarities with transformed cancer cells, including spontaneous production of matrix metalloproteinases (MMPs). Altered or chronic activation of proto-oncogenic Ras family GTPases is thought to contribute to inflammation and joint destruction in RA, and abrogation of Ras family signaling is therapeutic in animal models of RA. Recently, expression and post-translational modification of Ras guanine nucleotide releasing factor 1 (RasGRF1) was found to contribute to spontaneous MMP production in melanoma cancer cells. Here, we examine the potential relationship between RasGRF1 expression and MMP production in RA, reactive arthritis, and inflammatory osteoarthritis synovial tissue and FLS.