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PubMedDate not supplied

[Conserved regions of potential ORF1 protein products of mobile elements and retroviral proteins, encoded by the gag gene].

Computer search for homology regions of retroelement ORF1 protein products and retroviral gag-encoded proteins was performed using nucleotide and protein sequences of 113 retrotransposons, conservative domains were found in amino acid sequences encoded by viral gene gag: 22 and 17 amino acid residues in capsid and nucleocapsid proteins, respectively. Similar regions were found in potential protein products of ORF1. Another conservative region was revealed by multiple alignment in amino acid sequences of potential protein products of ORF1 of mobile elements and in p19 matrix protein of some retroviruses; this region is different in mobile elements from different classes, but within each class it shows high similarity. The secondary structure of this region is an alpha-helix.

Amino Acid Sequence↗
PubMed1996

Mutations at the capsid-nucleocapsid cleavage site of gag polyprotein of Moloney murine leukemia virus abolish virus infectivity.

Capsid protein CAp30 and nucleocapsid protein NCp10 of Moloney murine leukemia virus (MoMuLV) are the 2 major proteic components of the virion core and are generated by processing of the gag polyprotein precursor, Pr65gag, by the viral protease. In the virion core, several hundred NCp10 molecules are bound to the genomic RNA dimer forming the nucleocapsid structure. In the course of virus assembly, NC protein, as the mature NCp10 and/or as the gag precursor, appears to direct genomic RNA packaging. In vitro, NCp10 has nucleic acid binding and annealing activities and promotes viral RNA dimerization and the annealing of replication primer tRNAPro to the primer binding site (PBS) which is necessary for the initiation of reverse transcription. To investigate whether maturation of NCp10 is required for virus formation, we substituted charged residues for the hydrophobic amino acids at the capsid-nucleocapsid protein cleavage site in order to prevent maturation of NCp10. Here we report that these mutations abolished maturation of capsid protein CAp30 and NCp10 by the viral protease in vitro. When these mutations were introduced into an infectious MoMuLV molecular clone, Pr65gag precursor was synthesized in transfected cells but virion production was strongly diminished and mutant viruses were not infectious. These results suggest that maturation of NCp10 is required for optimal virion release and production of infectious virus.

Binding Sites↗
PubMed1996

Sedation in dentistry. Part 2: Management of the gagging patient.

Sedation should be considered as a useful part of the general dental practitioner's armamentarium and as an important alternative to general anaesthesia in selected cases. In this, one of a series of articles on the uses of sedation in various circumstances, the management of the gagging patient is discussed. The many factors involved in the aetiology of the hyperactive gag response are reviewed and measures for dealing with it suggested.

Adaptation, Psychological↗
PubMedDate not supplied

Suppression and prevention of the gag reflex with a TENS device during dental procedures.

Individuals who are prone to gagging and apprehension during dental treatments present a problem for the clinician and themselves. Patients may delay prescribed therapy or interfere with the fabrication of accurate oral impressions and diagnostic radiographs, because of this fear. The common wisdom has been to try one of the following procedures: (1) distraction of the patient, (2) forced respiration, (3) induced lagophthalmus, or (4) hypnosis. A preventive approach suggests that the sensory stimulation of the cranial nerves of the superior laryngeal nerve branch, (Cr N, IX, pharyngeal branch of X, Cr. N. V, and Cr N. X.) would block the physiologic response of gagging and retching.

Adult↗
PubMed1997

Molecular basis of the altered gag p19 protein (MA) of the transformation-defective mutant of Rous sarcoma virus, tdPH2010.

The transformation-defective mutant of Rous sarcoma virus (RSV), tdPH2010, has a gag p19 (matrix; MA) protein which migrates on SDS-polyacrylamide gels faster than that of the parental (tsNY68) as well as other wild-type strains of RSV. To study the molecular basis of this altered migration pattern and its biological significance, the nucleotide sequence of the p19 region of tdPH2010 was determined. Comparison of the nucleotide sequence of tdPH2010 with that of the Schmidt-Ruppin A strain of RSV revealed a point mutation at nucleotide 755 (G to A), resulting in an amino-acid substitution at residue 126 of p19 (Glu to Lys). Acidic-methanol esterification of free carboxyl groups suppressed the difference in electrophoretic mobility of p19 between tdPH2010 and the wild-type virus. Recombinant virus constructs having the mutated gag region of tdPH2010 produced a p19 with the same electrophoretic mobility as the p19 of tdPH2010. We concluded that the point mutation caused the altered electrophoretic behavior of p19 of tdPH2010. The mutation had no effect on the growth of infected cells.

Amino Acid Sequence↗
PubMed1998

[Phenotypic variability in gag-myc transgenic mice].

The study of neoplastic growth capacity in gag-myc F3-F4 transgenic mice showed that they retain the capacity to develop hyperplasia and benign and malignant tumors same as F0-F2 transgenic mice do. However, the histological spectrum of tumors was much narrower, chiefly, due to the absence of rare patterns. The tumors in F3-F4 transgenic mice were mainly lymphomas and epithelial tumors of endocrine or exocrine glands. The incorporation of gag-myc in the genome of F3-F4 transgenic mice failed to tell on the variation of such quantitative polygenic characteristics as body mass and growth.

Age Factors↗
PubMed1999

GAG deletion in the DYT1 gene in early limb-onset idiopathic torsion dystonia in Germany.

We examined 57 patients with idiopathic torsion dystonia (ITD) for the 3-bp GAG deletion in the DYT1 gene on human chromosome 9q34. Three of five patients with early limb-onset ITD, one of them with a positive family history, tested positive for the mutation, as did one young patient with multifocal dystonia and a short course of the disease. Two patients with early-onset generalized dystonia beginning in the cervical muscles, as well as five other patients with multifocal, 14 patients with segmental, and 30 patients with focal cervical dystonia did not carry the mutation. This suggests that the GAG deletion is responsible for a major portion of cases of typical early limb-onset dystonia, but not for other types of dystonia, in our population.

Adolescent↗
PubMed2000

The DYT1 GAG deletion is infrequent in sporadic and familial writer' s cramp.

A 3-base pair (GAG) deletion in the DYT1 gene has recently been found to be responsible for most cases of early-onset primary generalized dystonia. In some cases, this mutation has been associated with writer's cramp. To determine the frequency of this mutation in a larger series of patients, we examined 44 index patients with sporadic or familial (seven patients) writer's cramp for the presence of the DYT1 GAG deletion, including eight patients with segmental dystonia involving at least one upper limb. We found the mutation in none of these index patients, which confirms that isolated writer's cramp is only in rare cases a phenotypic manifestation of this mutation, even if a positive family history of writer's cramp is present.

Adult↗
PubMed1979

Moloney lymphoma cells express a polyprotein containing the GAG gene-coded p15 and the Moloney leukemia virus-induced cell surface antigen (MCSA).

The relationship between MCSA and the viral structural proteins in YAC Moloney lymphoma cells was further investigated by using membrane immunofluorescence and immunoadsorbent columns. As previously observed, MCSA showed only minimal capping and thereby differed in behaviour from gp70, p30 and p12 virion antigens. Whereas antibody-induced capping of gp70 did not change the membrane distribution of MCSA, co-capping was observed between MCSA and p30 and p12 gag protein antigens. This indicated that, whereas MCSA is distinct from gp70, it is linked to p30 and p12 on the membrane of living cells. It was then attempted to isolate MCSA on anti-p30 and anti-p15 immunoadsorbent columns from solubilized YAC cells. Contrary to what was expected, no MCSA was found to the anti-p30 column. On the other hand, a part (10-15%) of the MCSA was bound to the anti-p15 column, indicating that MCSA is linked to the gag p15.

Animals↗
PubMed1988

Structure of a collagen-GAG dermal skin substitute optimized for cultured human epidermal keratinocytes.

Collagen and glycosaminoglycan (GAG) dermal skin substitutes (membranes) were studied as substrates for cultured human epidermal keratinocytes. Structure of dermal substitutes was optimized for pore size to promote ingrowth of fibrovascular tissue from the wound bed and for culture of human keratinocytes of the membrane's surface. Pore size of the freeze-dried material was regulated by control of the temperature of freezing between -50 degrees C and -20 degrees C and by concentration of starting materials between 0.17% and 1.62% wt/vol. A nonporous surface of collagen-GAG was laminated to the membranes to provide a planar substrate for cultured epidermal keratinocytes. Thickness of dermal substitutes was regulated by control of the volume and concentration of starting materials. Biotin was conjugated to solubilized collagen for binding with avidin of specific quantities of biologically active molecules. The optimized membranes are suitable substrates for the culture of human epidermal keratinocytes, and together with the cells yield a composite material that is histologically similar to skin.

Artificial Organs↗
PubMed2001

Growth factor regulation of smooth muscle actin expression and contraction of human articular chondrocytes and meniscal cells in a collagen-GAG matrix.

Recent work has demonstrated that human articular chondrocytes and meniscus cells can express the gene for a contractile actin isoform, alpha-smooth muscle actin (SMA), in vivo. The objective of the present study was to evaluate the effects of two growth factors, transforming growth factor (TGF)-beta1 and platelet-derived growth factor (PDGF)-BB, on the SMA content of these cells and their contraction of a collagen-glycosaminoglycan (GAG) analog of extracellular matrix in vitro. TGF-beta1 was found to markedly increase SMA content of the cells and PDGF-BB decreased SMA expression, with both findings achieving statistical significance. A notable finding was the increased contraction of the collagen-GAG matrix induced by TGF-beta1 and the decrease in contraction resulting from PDGF-BB treatment, indicating a causal relationship between expression of SMA and the contractility of the cells. A novel cell force monitor, employed to estimate the force exerted per cell, demonstrated a higher force exerted by the TGF-beta1-treated cells. The findings demonstrate that the expression of SMA by articular chondrocytes and meniscal cells and their associated contractile behavior can be regulated by selected growth factors. This work provides a foundation for the rational investigation of the mechanisms underlying SMA-enabled contraction of these cell types and the control of this behavior in tissue engineering.

Actins↗
PubMed1983

Pharmacokinetic study of methyl glyoxal-bis-guanylhydrazone (methyl-GAG).

Using a paired ion exchange high pressure liquid chromatographic assay, pharmacokinetic evaluation of methyl glyoxal bis guanylhydrazone (methyl-GAG) was performed in nine male New Zealand albino rabbits following administration of a single intravenous bolus dose of 50 mg/kg B.W (550 mg/m2 BSA). Blood samples were collected before and at intervals of 5, 10, 15, 30 min and 1, 2, 3, 4, 6, 8, 12, 18, and 24 h after administration of the drug. The analysis of experimental data indicates a three compartment open model with first order elimination from the central compartment described by the equation Cpt = A.e-alpha t + B.e-beta t + C.e-gamma t, where A, B, C, are 107.985, 4.785, and 0.763 micrograms/ml, respectively. alpha, beta, gamma, are 5.466, 0.487, and 0.030 h-1, respectively, and T1/2 alpha, beta, gamma are 7.6, 85.3 min and 23.1 h, respectively. The mean volume of distribution in the central compartment Vc was 0.44 liters (1)/kg, volume of distribution Vdarea 30.326 1/kg, and the total body clearance 0.9097 1/kg/h. The existence of a long terminal plasma half life of methyl-GAG reported previously in human studies was also confirmed in experimental animals and may explain the cumulative toxicity of this drug.

Animals↗
PubMed1984

Extracellular glycosaminoglycans (GAG) released by chick embryonic fibroblasts. A possible involvement of surface receptors.

Administration of Concanavalin A (Con A) to cultured skin fibroblasts derived from chick embryos at two developmental stages produce variations in the relative concentration of individual glycosaminoglycan (GAG) secreted by the cells. This effect is different: at 7 days (increase of hyaluronic acid and dermatan sulphate and decrease of chondroitin sulphate) and at 14 days (dermatan sulphate is not detectable). All the cells bind the Con A specifically, but a different pattern of agglutination is present in fibroblasts of the two embryonic ages. Since Con A is well known to bind carbohydrate-containing surface proteins, the result suggests that the release of GAG by chick embryonic fibroblasts can be modulated by cell surface receptors.

Animals↗
PubMed1988

Monoclonal glucose-oxidase-anti-glucose-oxidase (GAG) immunosandwich assay for the detection of monoclonal antibodies on routine hematological smears.

A murine monoclonal antibody specific for aspergillus niger glucose oxidase has been prepared and used in an unlabeled antibody bridge technique for the detection of monoclonal antibodies. This procedure--the monoclonal glucose oxidase anti-glucose oxidase (GAG) immunosandwich assay--provides excellent immunocytochemical labeling of routine hematological films in combination with optimal preservation of cellular details. In contrast to conventional immunofluorescence procedures, routine hematological films can be used, and these can be stored before and after the immunolabeling. Compared with other immunoenzyme techniques such as those using alkaline phosphatase or peroxidase, the GAG assay is as sensitive and has the advantage that no problems with endogenous enzyme activity are encountered. The availability of alcohol-resistant disclosing reagents allows for routine hematological counterstaining which provides a very clear visualization of both the immunoreaction and the individual morphology of the blood cells.

Antibodies, Monoclonal↗
PubMed1999

Stock Identification of Gag, Mycteroperca microlepis, Along the Southeast Coast of the United States.

: The gag grouper Mycteroperca microlepis is an important component of commercial and recreational fisheries along the South Atlantic coast of the United States and in the Gulf of Mexico. Over the past two decades, this species has experienced significant declines in abundance and an increasing skew in sex ratios. Analysis of microsatellite DNA variation in this species shows mosaic patterns of population subdivision and significant departures from Hardy-Weinberg equilibrium in all sampling locations. Given the length of the pelagic stage (egg and larvae), the prevailing current patterns, and the migratory capabilities of the adults, it is unlikely that these observations are the result of restricted gene flow among genetically differentiated populations. The apparent structure of gag populations most likely reflects inbreeding in size-limited populations. Population declines, skewed sex ratios, and perhaps variance in female fecundity appear to have acted in concert to limited the number of individuals that contribute to a given year class. These data are reinforced by studies of other fish stocks that have experienced precipitous declines over the past two decades.

Journal Article↗
PubMed1992

Collagen types I and III, collagen content, GAGs and mechanical strength of human atherosclerotic plaque caps: span-wise variations.

Measurements of total collagen, of the ratio of collagen types III/(I+III) and of sulphated glycosaminoglycans (GAGs) were compared with mechanical strength for individual ulcerated and non-ulcerated human aortic plaque caps and with intima adjacent to the plaques. The distributions of the collagen type ratio were similar for both ulcerated and non-ulcerated plaque caps but different from that of the adjacent intima. The proportions of different collagen types were not related to fracture stress and are thus unlikely to affect the potential to ulcerate. The distributions of the sulphated GAGs showed lower amounts for the plaque caps compared with the nearby intima, with the centres of ulcerated plaque caps having the lowest values. Total collagen had higher values in the peripheries of plaque caps compared with the nearby intima, but was distinctly lower in the centres of ulcerated plaque caps. Plaque caps appeared to require a higher collagen content than adjacent intima to support a given level of mechanical strength, suggesting that while collagen production had occurred in the plaque caps it was not as efficiently organized to resist fracture as a similar amount of collagen in the adjacent intima. Ulcerated plaque caps are notable for much larger transverse (centre vs. periphery) gradients of connective tissue constituents than for non-ulcerated plaque caps. The development of these transverse gradients may be a critical aspect in determining the propensity of a plaque to ulcerate.

Aortic Diseases↗
PubMed1991

Absolute in vivo translation rates of individual codons in Escherichia coli. The two glutamic acid codons GAA and GAG are translated with a threefold difference in rate.

We have determined the absolute translation rates for four individual codons in Escherichia coli. We used our previously described system for direct measurements of in vivo translation rates using small, in-frame inserts in the lacZ gene. The inserts consisted of multiple synthetic 30 base-pair DNA oligomers with high densities of the four individual codons, GAA (Glu), GAG (Glu), CCG (Pro) and CGA (Arg). Our method is independent of expression level, of mRNA half-life and of transcription rate. Codon GAA was found to be translated with a rate of 21.6 codons/second whereas codon GAG was translated 3.4-fold slower (6.4 codons/s). These two codons are read by the same tRNA species. Codon CCG and CGA are both read by abundant tRNA species but nevertheless we found them to be translated slowly with rates of 5.8 and 4.2 codons/second, respectively. The context of these codons were varied, but we found no significant influence of context on their translation rates and we suggest a mechanism for why context may not affect translation rates. One insert with a low translation rate gave results that most readily can be explained by assuming queue formation of ribosomes on the insert. Such a queue was found to reduce the expression level by approximately 35%. Our experiments allowed us to estimate the average distance between ribosomes and thereby the translation initiation frequency on the wild-type lacZ mRNA. This was found to be one per three seconds.

Base Sequence↗
PubMed1984

Coordination of cleavage of gag and env gene products of murine leukemia virus: implications regarding the mechanism of processing.

Mouse 3T6 cells infected with Murine Leukemia Virus (MuLV) were cloned to yield several sublines producing viruses distinct from one another with respect to the ratio of uncleaved to cleaved gag gene-coded polyprotein, Pr65gag. The virus produced by the cloned sublines also differed in the ratio of the env gene-coded protein, p15E, to its product, p12E. The two ratios, Pr65gag/p30 and p15E/p12E, were found to be highly correlated among the cloned cell lines. Velocity gradient separation of the virions produced by individual sublines, followed by polypeptide analysis, demonstrated that the particles were inhomogeneous with respect to extent of cleavage both of PR65gag and of p15E. The two cleavages were again highly correlated. These data indicate that the gag and env gene product cleavages are not independent events but are tightly coupled.

Animals↗