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At least 19 recordsLinked to original sources
PubMed1991

Conditioning of the rabbit's nictitating membrane response to a CSA-CSB-US serial compound: manipulations of CSB's associative character.

Response acquisition to a trace conditioned stimulus (CSA) can be facilitated by insertion of a second stimulus (CSB) at the end of the trace interval just before the unconditioned stimulus (US). This effect may arise from serial mediation of trace conditioning, second-order conditioning, or both. Whereas serial mediation relies only on the presence of CSB, associative transfer relies on CSB's associative strength. In the present experiments, the presence of CSB was fixed, whereas CSB's associative strength was manipulated by (a) extinction of CSB, (b) latent inhibition of CSB, and (c) prior CSB-US pairings. In the first 2 cases, the level of responding to CSA was reduced in a fashion parallel to that of CSB. However, in the third case, partial blocking of conditioned response (CR) acquisition to CSA was observed. The results are discussed with reference to the role of associative transfer to both facilitating and blocking CR acquisition to CSA.

Animals↗
PubMed2024

The ARK2N-CK2 complex initiates transcription-coupled repair through enhancing the interaction of CSB with lesion-stalled RNAPII.

Transcription is extremely important for cellular processes but can be hindered by RNA polymerase II (RNAPII) pausing and stalling. Cockayne syndrome protein B (CSB) promotes the progression of paused RNAPII or initiates transcription-coupled nucleotide excision repair (TC-NER) to remove stalled RNAPII. However, the specific mechanism by which CSB initiates TC-NER upon damage remains unclear. In this study, we identified the indispensable role of the ARK2N-CK2 complex in the CSB-mediated initiation of TC-NER. The ARK2N-CK2 complex is recruited to damage sites through CSB and then phosphorylates CSB. Phosphorylation of CSB enhances its binding to stalled RNAPII, prolonging the association of CSB with chromatin and promoting CSA-mediated ubiquitination of stalled RNAPII. Consistent with this finding, Ark2n-/- mice exhibit a phenotype resembling Cockayne syndrome. These findings shed light on the pivotal role of the ARK2N-CK2 complex in governing the fate of RNAPII through CSB, bridging a critical gap necessary for initiating TC-NER.

DNA Repair Enzymes↗
PubMed1987

Isolation of a cDNA clone for murine catalase and analysis of an acatalasemic mutant.

We have investigated the genetic control of murine catalase expression by analyzing catalase transcription and translation products from the tissues of control (Csa) and acatalasemic (Csb) mouse strains. Csb animals possess nearly normal catalase enzyme activity levels in liver, while displaying approximately 20 and 1% of normal activity levels in kidney and red blood cells, respectively. Immunoblot analyses of catalase in these tissues have revealed reduced levels of immunologically reactive catalase protein in Csb kidney and red blood cells, paralleling the reduction of catalase enzyme activity in these tissues. In order to determine the molecular basis for Csb acatalasemia, we have isolated a cDNA clone for murine catalase and have used this probe to analyze Csa and Csb genomic DNA and catalase mRNA. These studies have revealed: 1) no restriction fragment length polymorphisms between Csa and Csb genomic DNAs; 2) no differences in the levels of Csa and Csb catalase mRNA within a single tissue; and 3) no differences in the sizes of Csa and Csb catalase mRNAs. These observations suggest that the genetic defect that produces the tissue-specific reduction of catalase expression in Csb mice is not due to a marked rearrangement of DNA within the Csb catalase structural gene. Furthermore, the Csb mutation does not act at the level of gene transcription or mRNA stability, but rather at the level of mRNA translation and/or catalase protein turnover.

Acatalasia↗
PubMed1992

Effect of heating on nutritional quality of conventional and Kunitz trypsin inhibitor-free soybeans.

Five 10-day chick growth experiments and an amino acid digestibility assay were conducted to assess the effect of steam heating on in vivo protein quality of raw, full-fat Kunitz trypsin inhibitor-free soybeans (KFSB) compared with raw, conventional full-fat soybeans (CSB). Protein solubility in .2% KOH was also evaluated as an in vitro test of in vivo protein quality for underprocessed CSB. The CSB and KFSB were autoclaved for 0, 3, 6, 9, 12, 15, 18, or 21 min at 121 C and 124 kPa. The soybeans were then fed to 8- or 9-day-old chicks as the sole source of protein in dextrose and soybean diets containing 23% protein. Growth performance of chicks fed raw KFSB was superior to that of chicks fed raw CSB. Growth performance of chicks fed autoclaved KFSB or CSB increased and pancreas weight (percentage of body weight) decreased as autoclaving time increased. Slightly less autoclaving time was consistently required to achieve maximum chick performance for KFSB compared with CSB. Less autoclaving time was also required to obtain maximum digestibility of amino acids in KFSB compared with CSB. Urease activity of the soybeans decreased as autoclaving time increased, whereas protein solubility in .2% KOH for CSB did not change consistently in response to heating time. The results of the present study indicate that raw KFSB must be heated to obtain maximum protein quality for chicks and that protein solubility in KOH is not a sensitive indicator of underprocessing of CSB soybeans.

Amino Acids↗
PubMed1992

Sulfonic acid dyes: inhibition of the human immunodeficiency virus and mechanism of action.

Over 50 different commercially available sulfonic acid-containing dyes were analyzed for their ability to prevent HIV-1-induced cell killing and in inhibiting HIV-1 replication. Compounds of remarkably similar structure, but with differing patterns of sulfonic acid group substitutions, had a wide range of potency in inhibiting HIV-1. Chicago sky blue (CSB) was highly effective in the inhibition of HIV-1 with less toxicity to CEM-SS cells than most of the other sulfonated dyes tested. Synthesis of CSB was undertaken to produce a product greater than 98% pure and this compound was used to elucidate the possible mechanisms by which this class of structurally related compounds inhibits HIV-1. Addition of CSB to cells infected at high multiplicity at any time up to 24 h after infection, unlike dideoxycytidine (ddC) or oxathiin carboxanilide (OC), inhibited HIV-1-induced cell killing. Other postinfection time course studies revealed that CSB had to be present for 24 h or longer immediately after infection to be protective. Virus binding to cells occurred in the presence of CSB, but the requirement for virion envelope-cell membrane fusion was delayed. CSB was a potent inhibitor of the reverse transcriptase (RT) of both HIV-1 and HIV-2, although it was less active against HIV-2 in a cell killing-based assay. CSB also inhibited Rauscher and LP-BM5 murine leukemia viruses. CSB appears to disrupt the interaction between viral proteins and cell membranes, both in the fusion step early in the infection cycle and in the development of syncytia in the late stages of virus infection.

Antiviral Agents↗
PubMed1992

Comparative results of carotid-subclavian bypass and axillo-axillary bypass in patients with symptomatic subclavian disease.

The results of 26 carotid-subclavian bypass (CSB) and 17 axillo-axillary bypass (AAB) procedures, performed to treat symptomatic lesions of the proximal subclavian artery, were reviewed. Nine graft failures (seven CSB and two AAB) occurred (mean follow-up: CSB = 60.5 +/- 41 months; AAB = 67.8 +/- 48 months). All CSB graft thromboses were observed in patients with an associated ipsilateral carotid lesion, surgically treated or not (p less than 0.05). Cumulative 5- and 10-year patency rates were 78.3 and 62.9% for the CSB group and 87.9% for the AAB group (N.S.). In patients with an associated ipsilateral carotid lesion, 5- and 10-year patency rates were 66.0% and 40.8% for the CSB group and 100% for the AAB group (p less than 0.05). Both the surgical procedures were safe and effective with excellent results in terms of operative mortality, major morbidity and long-term patency. CSB is the procedure of choice for the treatment of proximal subclavian artery disease for its physiological characteristics and for graft shortness. However AAB must be considered a suitable alternative and preferred when a concomitant ipsilateral carotid lesion is present. Recurrence of carotid stenosis or carotid lesion progression may cause the carotid-subclavian failure.

Aged↗
PubMed1992

Effects of a new molasses byproduct, concentrated separator byproduct, on nutrient digestibility and ruminal fermentation in cattle.

Continuous chromatographic separator techniques have allowed the extraction of more simple sugars from molasses (MOL). The resultant byproduct, concentrated separator byproduct (CSB), has reduced readily fermentable carbohydrates but elevated CP and mineral content. The feed value of CSB was compared to that of MOL in two separate trials. In Trial 1, a chopped forage mixture containing 84% meadow grass hay and 8% alfalfa hay was mixed with either CSB or MOL at 7.3% of DM. Diets were administered to four ruminally cannulated cows in a single reversal design. digestibility of DM, ADF, NDF, and CP were measured. Ruminal pH, ammonia nitrogen (NH3), VFA, total viable bacteria (TVB), cellulose-xylan fermenting bacteria (CXFB), and ciliated protozoa (PTZ) were evaluated. Blood profiles of electrolytes were also measured. Digestibility of DM, ADF, NDF, and CP were 69.03, 68.58; 57.48, 57.77; 65.62, 64.75; and 67.63, 65.07% for the MOL and CSB diets, respectively. Only CP digestibility differed (P less than .02). Ruminal pH, NH3, VFA, TVB, CXFB, and PTZ were 6.97, 6.93; 14.21, 16.71 mg/dL; 74.30, 74.78 mumol/mL; 26.79, 27.36 x 10(9)/mL; 21.72, 21.36%; and 13.90, 7.80 x 10(3)/mL for the MOL and CSB diets, respectively. Ruminal measurements did not differ. Blood electrolyte profiles were not altered. Trial 2 was similar to Trial 1 except the basal diet used was 47% barley grain, 35% alfalfa hay, and 10% barley straw. Either MOL or CSB was added at 7.3% of the DM. Digestibilities of DM, ADF, NDF, and CP were 69.52, 71.33; 35.96, 37.11; 27.93, 33.47; and 71.10, 73.66% for the MOL and CSB diets, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1976

The glycosaminoglycans of the human artery and their changes in atherosclerosis.

The changes in levels of glycosaminoglycans (GAGs) of the intima and media of the human artery in atherosclerosis were determined by a recently introduced two-dimensional electrophoresis technique that permits direct measurments of each of these macromolecules. To identify the arterial GAGs, they were fractionated by chromatography on a DEAE-Sephadex A-25 column, and the resulting three fractions (hyaluronic acid [HA], heparan sulfate [HS], and the partially separated chondroitin sulfates B [CSB] and C [CSC]) were analyzed for their electrophoretic mobilities by this electrophoretic method, for their digestability by highly specific hydrolases (leech hyaluronidase, heparinase, and chondroitinases ABC and AC) and for their iduronic acid content. From these studies we concluded that normal and atherosclerotic human aortas contain CSB, CSC, HA, and HS. Further, we demonstrated that CSB is a hybrid consisting of approximately 40% CSA and 60% CSB and that CSC appears to be a polymer consisting essentially of glucuronic acid and N-acetylgalactosamine-6-sulfate. Classical CSA as well as chondroitin (CH) were not present in detectable amounts. In the relatively normal intima, the mean concentrations of the GAGs were found to be 4.7, 20.9, 1.3, and 5.1 mg/g of dry, defatted, decalcified tissue for CSB, CSC, HA, and HS, respectively. With the progression of atherosclerosis, there was a pronounced decrease in the total GAG content (from 32 to 18 mg) associated with a decrease in the CSC and HS levels but without a change in the HA concentrations. Of particular interest, however, was the increase in the CSB level. In the media whose total GAG content averaged approximately 20 mg, no significant changes in these GAG levels were noted with the progression of the disease except for that of CSC. These findings may be important in explaining the increased lipoprotein and collagen deposition in the diseased aorta.

Aorta↗
PubMed1991

Temporal specificity in cross-modal transfer of the rabbit nictitating membrane response.

Two experiments examine cross-modal transfer of response features specific to the interstimulus interval (ISI) between a conditioned stimulus (CS) and an unconditioned stimulus. Rabbits were given initial training with a stimulus (CSA) in one modality (e.g., tone) at a designated ISI (e.g., 600 ms). Training was then shifted to a new stimulus (CSB) in another modality (e.g., light) at a new ISI (e.g., 400 ms). The timing of early conditioned responses (CRs) to CSB reflected the ISI of CSA. Ultimately, CRs to CSB shifted to a temporal location conforming to the ISI of CSB. When the ISI of CSB was shorter than that of CSA, CRs to CSA also shifted to a locus conforming to the ISI of CSB. The present results confirmed previous findings that training in one CS modality accelerates CR acquisition to a CS in another modality. The findings are compared with the transfer of response patterns in instrumental learning sets and are discussed regarding their implications for theories of cross-modal transfer.

Animals↗
PubMed1988

Death of the subcallosal glial sling is correlated with formation of the cavum septi pellucidi.

In this study we have examined the developmental fate of a population of cells that is located beneath the rostral corpus callosum during the perinatal period. These cells form a distinct slinglike structure along the geographically defined corticoseptal boundary (CSB) and may play a role in guiding callosal axons across the midline. The sling is a transient structure present in fetal and neonatal animals but not in adults. Here we show that the CSB cells die and that this debris is removed by macrophages. The sequence of cell degeneration in the CSB is highly stereotyped and follows a spatiotemporal pattern that is correlated with fusion of the cerebral hemispheres and subsequent growth across the midline of the callosal axons. The subcallosal location of the resorbing CSB is found in the exact place in which a fluid-filled cavity (the cavum septi pellucidi) is transiently found during the perinatal period. The tight temporal and spatial correlation between callosal axon decussation, degeneration of the CSB, and cavum septi formation suggests that these three phenomena may be causally related.

Aging↗
PubMed1991

Electron microscopic demonstration of glucocorticoid recognition sites on isolated rat hepatocytes.

Ultrastructural evidence is presented for the presence of membrane-bound glucocorticoid recognition and binding sites. Corticosterone was derivatized at 3 different positions and coupled covalently to bovine serum albumin (BSA). All three derivatives competed for binding of [3H]corticosterone by isolated rat hepatocytes. The most effective competitor, corticosterone-succinate-BSA (CSB), was adsorbed onto colloidal gold particles (CSB-gold, 17 +/- 3 nm dia). When isolated rat hepatocytes or mouse pituitary tumor cells (AtT 20) are incubated with CSB-gold, specific binding in the microvilli-rich region of these cells is seen. This binding of CSB-gold is reduced by about 50% in the presence of unlabelled CSB or corticosterone.

Animals↗
PubMed1990

Molecular analysis of an acatalasemic mouse mutant.

The Csb acatalasemia mouse mutant differentially expresses reduced levels of catalase activity in a tissue specific manner. In order to pinpoint the molecular lesion that imparts the acatalasemia phenotype in Csb mice we have utilized the polymerase chain reaction technique to isolate catalase cDNA clones from control and Csb mouse strains. Sequence analyses of these cDNA clones have revealed a single nucleotide difference within the coding region of catalase between control and Csb mice. This nucleotide transversion (G----T) is located in the third position of amino acid 11 in the catalase monomer. In control mouse strains glutamine (CAG) is encoded at amino acid 11, while in Csb mice this codon (CAT) encodes histidine. This amino acid is located within a region that forms the first major alpha-helix in the amino-terminal arm of the catalase subunit and, as such, may render the catalase molecule unstable under certain physiological conditions.

Amino Acid Sequence↗
PubMed1989

Conserved sequence blocks in kinetoplast minicircles from diverse species of trypanosomes.

Kinetoplast DNA minicircles from various species of trypanosomes are heterogeneous in nucleotide sequence to various degrees but in all instances contain a conserved sequence region of 100 to 200 base pairs present in one, two, or four copies per minicircle. Comparison of the conserved sequence regions of minicircles from eight species of trypanosomes revealed a common sequence motif consisting of three conserved sequence blocks (CSBs) present in the same order and with similar spacing in all species. In addition to the invariant 12-base-pair universal minicircle sequence (CSB-3), a 10-base-pair sequence (CSB-1) and an 8-base-pair sequence (CSB-2) are highly conserved in all minicircles. The overlap of CSB-1 and CSB-3 with previously identified 5' termini of newly synthesized minicircle H and L strands, respectively, and the presence of this conserved sequence motif in minicircles from diverse species suggest that these CSBs may determine a common mechanism of minicircle replication.

Animals↗
PubMed1987

Inheritance and expression of tissue-specific catalase activity during development and aging in mice.

The catalase activity in the liver, kidney, lung, and blood hemolysate was measured in newborn, 21-, 70-, 175-, and greater than 400-day-old mice from the strains BALB/c, Csb, C3H/HeSnJ, C3H/S, C57BL/6J, SW, and 129/ReJ. Catalase activity was found to be highest in the liver (approximately 0.33 U/mg protein) followed by the kidney (approximately 0.13 U/mg protein), lung (approximately 0.05 U/mg protein), and blood hemolysate (approximately 0.03 U/mg protein). ANOVA analysis indicated significant differences in enzyme activity among strains and age groups studied. The developmental profiles of enzyme activity were tissue and strain specific. Catalase activity in the blood, for example, was generally higher at birth and at old age, whereas the kidney catalase activity was low at birth and increased substantially with age. Strains could be classified as normal (129/ReJ, BALB/c, C3H/HeSnJ, C3H/S), hypocatalasemic (C57BL/6J, SW), and acatalasemic (Csb) with respect to enzyme activity and it was on this basis that the inheritance of the catalase phenotype was studied using appropriate crosses. The enzyme activity level in each tissue appears to be governed by a unique set of genetic regulators/modifiers that interact with a single structural gene (Cs) or its product to produce the catalase phenotype. Some of these (e.g., Ce-1 and Ce-2) have been previously described but based on the results of various crosses reported here, more must exist that remain still uncharacterized at the molecular level. Models proposed for the inheritance of the catalase phenotype vary in complexity from single allelic differences between strains (e.g., BALB/c x Csb; blood) to a system of multiple interacting genetic determinants (e.g., BALB/c x Csb; liver) each having dominant (e.g., C57BL/6J over BALB/c; liver) and recessive components (e.g., gene(s) conferring the acatalasemic phenotype in BALB/c x Csb; blood and kidney). Such results are important and offer an interesting model to further characterize aspects of eukaryotic gene regulation.

Aging↗