Biomedical subjects
Publications and source records attributed to M Fried.
The human gene encoding the muscle-specific beta-enolase has been isolated. The beta-enolase gene was mapped to chromosome 17 by analysis of a panel of rodent-human somatic cell hybrids. The gene was further localized to the short arm and tentatively to the region 17pter-p11 by analysis of cell hybrids and transfectant cell lines carrying different portions of chromosome 17.
Using an interspecies backcross, we have mapped the HOX-5 and surfeit (surf) gene clusters within the proximal portion of mouse chromosome 2. While the HOX-5 cluster of homeobox-containing genes has been localized to chromosome 2, bands C3-E1, by in situ hybridization, its more precise position relative to the genes and cloned markers of chromosome 2 was not known. Surfeit, a tight cluster of at least six highly conserved "housekeeping" genes, has not been previously mapped in mouse, but has been localized to human chromosome 9q, a region of the human genome with strong homology to proximal mouse chromosome 2. The data presented here place HOX-5 in the vicinity of the closely linked set of developmental mutations rachiterata, lethargic, and fidget and place surf close to the proto-oncogene Abl, near the centromere of chromosome 2.
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The clustered arrangement (no two adjacent genes are separated by more than 73 base pairs [bp] and two genes overlap by 133 bp at their 3' ends) of the four genes (Surf-1 to -4) identified so far in the mouse surfeit locus (T. Williams, J. Yon, C. Huxley, and M. Fried, Proc. Natl. Acad. Sci. USA 85:3527-3530, 1988) is the tightest gene clustering found in any mammalian genome to date and strongly suggests the possibility of cis-interaction and/or coregulation of gene expression. Thus, we are analyzing the surfeit genes in detail and are defining the extent of the cluster. Here we present the sequence of the entire Surf-4 gene and define the 3' and 5' extents of its mRNAs. The Surf-4 gene has heterogeneous transcriptional start sites, and its 5' end lies in a CpG-rich island. The gene specifies three mRNAs, with the two most abundant mRNAs differing in the locations of their 3' polyadenylation sites. Only the most abundant Surf-4 mRNA would overlap the 3' end of the Surf-2 gene by 133 bp. Two new genes (Surf-5 and Surf-6) have been identified in the surfeit gene cluster by Northern (RNA) blot analysis. The 5' end of Surf-6 lies within the CpG-rich island about 8 kilobases (kb) from the CpG-rich island containing the 5' end of Surf-3, and Surf-5 lies between Surf-3 and Surf-6. Thus, the cluster contains a unique arrangement of four CpG-rich islands within 32 kb associated with the 5' ends of the six surfeit genes. The neighboring CpG-rich islands have been located 500 and 100 kb distant on either side of the surfeit cluster, indicating that the end of the cluster of islands has been reached.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Little is known about how gastric and pancreatobiliary responses differ after intake of elemental diets from responses to polymeric food. We therefore compared pancreatic and biliary secretions after gastric instillation of albumin (7 g%, with dextrose 21 g%) with an elemental diet in 6 healthy volunteers. The elemental diet contained amino acids (7 g%, with dextrose 21 g%) in the same molar composition as the albumin. Furthermore, we studied the effect of a pure intragastric dextrose solution (21 g%) on pancreatobiliary secretions, as glucose constitutes a major component of elemental diet formulas. The various pancreatobiliary responses were tested against a maximal i.v. cholecystokinin stimulus. The dextrose, amino acid, and albumin meals emptied at similar rates, and gastric emptying was completed within 3 h. Similar pancreatobiliary responses were observed after the albumin and amino acid meals, but response to both the amino acid and albumin meals was smaller than to the intravenous cholecystokinin stimulus. The glucose meal caused a marked and sustained stimulation of pancreatobiliary outputs, which did not differ significantly from the other test meals. However, lower cholecystokinin levels were observed after the glucose meal compared with distinct cholecystokinin release after the albumin and amino acid meals. We conclude first that there are no major differences in secretory responses between elemental (amino acid) and polymeric (protein) meals and second, that intragastric pure glucose meals strongly stimulate pancreatobiliary secretions. The marked pancreatic and biliary responses to intragastric dextrose cannot be fully explained on the basis of cholecystokinin release, suggesting that this response is probably mediated by neural mechanisms.
To clarify the role of GIP (gastric inhibitory polypeptide) as an incretin, we related temporally the gastric emptying of fat, protein and glucose to plasma levels of glucose, GIP and insulin in man. Five healthy volunteers with a multiple lumen duodenal tube ingested a mixed meal with phase-specific markers for the aqueous phase, liquid fat and the solid protein phase. Duodenal passage was determined by intraduodenal infusion of a second set of phase-specific non-absorbable markers. Plasma insulin rose rapidly from a basal value of 59 pM to 300 pM at 60 min, and then declined to reach basal levels after 180 min. By contrast, plasma GIP rose more slowly than insulin, from a basal value of 9.4 pM, and remained elevated, in the range of 14-18 pM, throughout the 240 min observation period. The time course of plasma insulin concentration paralleled gastric emptying of the aqueous phase, containing most of the meal's glucose (r = 0.952, P less than 0.001). The time course of plasma GIP concentrations paralleled the gastric emptying of fat and protein (r = 0.763-0.834; P less than 0.01-0.05). Plasma insulin concentrations showed no correlation to the rate of emptying of fat and protein (r = 0.142-0.420; n.s.) and to plasma levels of GIP (r = 0.365; n.s.). The threshold for plasma glucose at which GIP would exert an incretin effect only reached at one time point, 30 min after ingestion of the meal. Our findings of simultaneously tracked gastric emptying of meal nutrients, hormone release and plasma glucose levels do not support an important physiological role for GIP as an insulinotropic hormone after ingestion of mixed meals in man.
We have devised a strategy that utilizes the polymerase chain reaction (PCR) for the detection and isolation of intron-containing genes in the presence of an abundance of processed pseudogenes. The method depends on the genomic DNA sequence between the PCR primers spanning at least one intron in the gene of interest, resulting in the generation of a larger intron-containing PCR product in addition to the smaller PCR product amplified from the intronless pseudogenes. A unique intron probe isolated from the larger PCR product is used for the detection of intron-containing clones from recombinant DNA libraries that also contain pseudogene clones. This method has been used successfully for the selective isolation of an intron-containing rat L19 ribosomal protein gene in the presence of multiple pseudogenes. Analysis of a number of mammalian ribosomal protein multigene families by PCR indicates that they all contain only a single gene with introns.
The Surfeit gene cluster which contains at least four very tightly spaced unrelated genes, one of which encodes the ribosomal protein L7a, has been localized by an analysis of somatic cell hybrids to the long arm of chromosome 9. By the use of in situ hybridization the Surfeit locus has been further mapped to 9q33-34.
The mouse Surfeit locus, which contains a cluster of at least four genes (Surf-1 to Surf-4), is unusual in that adjacent genes are separated by no more than 73 base pairs (bp). The heterogeneous 5' ends of Surf-1 and Surf-2 are separated by only 15 to 73 bp, the 3' ends of Surf-1 and Surf-3 are only 70 bp apart, and the 3' ends of Surf-2 and Surf-4 overlap by 133 bp. This very tight clustering suggests a cis interaction between adjacent Surfeit genes. The Surf-3 gene (which could code for a basic polypeptide of 266 amino acids) is a highly expressed member of a pseudogene-containing multigene family. By use of an anti-peptide serum (against the C-terminal nine amino acids of the putative Surf-3 protein) for immunofluorescence and immunoblotting of mouse cell components and by in vitro translation of Surf-3 cDNA hybrid-selected mRNA, the Surf-3 gene product was identified as a 32-kilodalton ribosomal protein located in the 60S ribosomal subunit. From its subunit location, gel migration, and homology with a limited rat ribosomal peptide sequence, the Surf-3 gene was shown to encode the mouse L7a ribosomal protein. The Surf-3 gene is highly conserved through evolution and was detected by nucleic acid hybridization as existing in multiple copies (multigene families) in other mammals and as one or a few copies in birds, Xenopus, Drosophila, and Schizosaccharomyces pombe. The Surf-3 C-terminal anti-peptide serum detects a 32-kilodalton protein in other mammals, birds, and Xenopus but not in Drosophila and S. pombe. The possible effect of interaction of the Surf-3 ribosomal protein gene with adjacent genes in the Surfeit locus at the transcriptional or posttranscriptional level or both levels is discussed.
We have investigated the subcellular localization, transforming capacity and cellular protein binding properties of a mutant middle T antigen, 82JF3. This mutant lacks the carboxyterminal 86 amino acids of middle T and, as expected, failed to associate with cellular membranes. Like other cytoplasmic mutants, it also failed to transform. Nevertheless, 82JF3 middle T antigen associated with pp60c-src and increased its tyrosine kinase activity. The associated pp60c-src was also cytoplasmic, raising interesting questions about the nature and formation of the complex. This soluble complex also contained very reduced levels both of the p81 protein and of associated phosphatidylinositol (PI) kinase activity. These results are consistent with the hypothesis that p81 is a component of PI kinase.
The authors report on their experience with the administration of Decaris (Levamisol) to patients with complication in the surgical wound after surgery. Decaris was administered on average 20.2 days after unsuccessful common local and general treatment. In patients with an anamnestic suspicion of immunodeficiency this drug was administered already before operation. After Decaris administration in 77% of the patients the wounds healed within 24 days. For patients with complications in surgical wounds Decaris treatment may be one of the possible conservative approaches to their condition.
Although the majority of severe combined immune deficiency (scid) mice lack functional lymphocytes, some (2-23%) appear to develop a limited number of B and T cells between 3 and 9 mo old. Most of these leaky scid mice were shown to contain very few clones (less than or equal to 3) of Ig-producing plasmacytes. Clonal progeny were distributed unevenly in the lymphatic tissues and appeared as discrete plasmacytic foci. In many cases, individual clones persisted for several months and produced abnormally high concentrations of Ig that included multiple isotypes. Functional T cells were inferred from the ability of leaky mice to reject allogeneic skin grafts, a T cell-dependent reaction. Interestingly, approximately 40% of leaky mice developed thymic lymphomas. In other respects, leaky mice resembled regular scid mice; e.g., their splenic cells failed to express common lymphocyte antigens (Ly-5[B220], Ly-1) and to proliferate in response to lymphocyte mitogens. Histologically, their lymphoid tissues retained the same general pattern of severe lymphocytic deficiency as scid mice.