Search PubMed⌕ Search

Biomedical subjects

N Oliver

Publications and source records attributed to N Oliver.

At least 37 records · Page 2Linked to original sources
PubMed1992

Keloid fibroblasts exhibit an altered response to TGF-beta.

Treatment with transforming growth factor beta 1 (TGF-beta 1) results in stimulation of total protein synthesis in normal dermal fibroblasts but not in keloid fibroblasts, suggesting that the TGF-beta regulatory program is altered in keloid fibroblasts. However, both keloid and normal fibroblasts treated with TGF-beta 1 exhibit accelerated fibronectin biosynthesis, indicating that keloid cells can respond to TGF-beta 1. In the absence of serum, the TGF-beta 1-induced increase in fibronectin biosynthesis occurs more rapidly in keloid fibroblasts, also suggesting modification of this regulatory pathway. The TGF-beta 1-mediated increase in keloid fibronectin production is independent of the steroid regulatory pathway for fibronectin, which accelerates synthesis by means of a post-transcriptional mechanism. Thus, TGF-beta 1 stimulation of fibronectin production in keloid cells is likely to involve a transcriptional mechanism and keloid overproduction of extracellular matrix components may be due to an inherent modification of the TGF-beta regulatory program.

Adolescent↗
PubMed1989

Fibronectin is overproduced by keloid fibroblasts during abnormal wound healing.

Wound healing in certain individuals leads to the development of keloid tumors which exhibit abnormal collagen metabolism and an increased abundance of extracellular matrix components. Comparison of fibronectin levels in fibroblasts derived from keloids and normal dermis revealed a relative increase in intracellular and extracellular fibronectin in the keloid-derived cells. While fibronectin was similarly processed, compartmentalized, and degraded by both cell types, fibronectin biosynthesis was found to be accelerated as much as fourfold in keloid fibroblasts due to a corresponding increase in the amount of accumulated fibronectin mRNA. These changes account for the elevated steady-state level of the molecule in keloid fibroblasts and suggest that increased fibronectin in keloid lesions is due to overproduction by the wound-healing fibroblasts. Glucocorticoid treatment stimulated fibronectin biosynthesis in both normal and keloid fibroblasts. However, the amount of stimulation was less for the keloid-derived cells, indicating a limitation on maximal rates of fibronectin biosynthesis. These observations suggest that separate mechanisms act to control basal and maximal rates of fibronectin production. Biosynthesis of the 140-kilodalton fibronectin receptor was also found to be increased in keloid fibroblasts, suggesting some level of coordinate regulation for fibronectin and fibronectin receptor expression.

Adult↗
PubMed1988

Nebulin cDNAs detect a 25-kilobase transcript in skeletal muscle and localize to human chromosome 2.

By virtue of the protein's size, myofibrillar localization, and proposed functional role, the gene encoding the giant sarcomere matrix protein nebulin represents a possible site for myopathic mutations. Using polyclonal anti-nebulin antisera to screen a cDNA expression library, we have isolated and characterized two separate human fetal muscle cDNA clones. By recovering fusion polypeptide-bound portions of our polyclonal antiserum and reutilizing them to probe Western blots, we further demonstrate that the expressed cDNAs encode polypeptide epitopes unique to the protein nebulin. Both cDNAs detect a 25-kb skeletal muscle RNA transcript and localize to human chromosome 2. The identification of nebulin cDNA clones enables the complete analysis of this enormous mRNA by transcript walking through muscle cDNA libraries. Here we report a restriction map of the 3' end of the human nebulin transcript, with reference to the genomic fragments identified by the cDNA.

Chromosome Mapping↗
PubMed1986

Effects of transformation on the expression of laminin and fibronectin by neural cells.

We have studied laminin and fibronectin expression in a collection of rat cerebellar neural cell lines transformed with a mutant of Rous sarcoma virus which is temperature sensitive for transformation. We show that regardless of their neuronal or glial properties the cell lines produce both laminin and fibronectin. Laminin is expressed in similar amounts in cell lines grown at either the permissive or nonpermissive temperature for transformation, while fibronectin is generally expressed at higher levels in cells kept at the nonpermissive temperature. To provide further evidence that neural cells can produce laminin and fibronectin, double label immunofluorescence studies were conducted on primary cerebellar cultures. Both laminin and fibronectin were found to be present in the primary culture, and laminin was found to be associated with a subpopulation of astrocytes.

Avian Sarcoma Viruses↗
PubMed1984

Comparison of mitochondrially synthesized polypeptides of human, mouse, and monkey cell lines by a two-dimensional protease gel system.

Mitochondrially synthesized polypeptides of human, monkey, and mouse cells were compared using SDS-polyacrylamide gel electrophoresis (SDS-PAGE). A single molecular weight variant, the major interspecific variant (MIV), was identified in human cells as compared to monkey and mouse. The peptide maps of MIV were compared between the three species using a two-dimensional proteolytic digest (2D-PD) gel system. A number of conserved peptides were found, indicating that the MIVs have a common function. Other MIV peptides were species specific. These results confirm the conserved nature of mitochondrial polypeptides and demonstrate the utility of 2D-PD gels in testing for protein alleles and detecting subtle protein variants.

Animals↗
PubMed1984

Abdominal pain in the elderly.

This article deals with the difficulties of diagnosing the cause of abdominal pain in the elderly and indicates a general approach to management of such patients. It does not specify diagnostic and treatment criteria for the numerous causes of pain nor the management in difficult cases (which should be resolved in consultation with a specialist).

Abdomen↗
PubMed1983

Regulation of fibronectin biosynthesis by glucocorticoids in human fibrosarcoma cells and normal fibroblasts.

When treated with the synthetic glucocorticoid dexamethasone, HT1080 human fibrosarcoma cells show changes in morphology, adhesion, and the extracellular matrix. Dexamethasone treatment results in a tenfold increase in the rate of fibronectin biosynthesis in HT1080 cells and a twofold increase in untransformed, normal human fibroblasts. Maximal induction levels are attained within one cell generation, while decay of the response requires several cell cycles. Pulse-chase studies showed that most of the newly synthesized fibronectin is secreted into the medium. The glucocorticoid antagonist, RU-486, blocks the dexamethasone-induced changes but does not alter the basal rate of fibronectin production. Therefore, fibronectin biosynthesis appears to be controlled by two distinct mechanisms--one, regulating basal rates of fibronectin production, which is transformation-sensitive and glucocorticoid-independent; and another, which is mediated by the glucocorticoid receptor, resulting in elevated rates of fibronectin biosynthesis upon dexamethasone treatment both in normal fibroblasts and in HT1080 cells.

Cells, Cultured↗
PubMed1981

Conserved autosomal syntenic group on mouse (MMU) chromosome 15 and human (HSA) chromosome 22: assignment of a gene for arylsulfatase A to MMU 15 and regional mapping of DIA1, ARSA, and ACO2 on HSA 22.

We have utilized a panel of Chinese hamster x mouse somatic cell hybrids segregating mouse chromosomes to assign a gene for arylsulfatase A (ARSA) to mouse chromosome 15. Considering our previous assignment of a gene for diaphorase-1 (DIA1) to the same mouse chromosome, we have evidence for another syntenic relationship that has been conserved, since the homologous loci for human ARSA and DIA1 are both located on human chromosome 22. Because MMU 15 and HSA 22 are quite dissimilar in size and banding patterns, we have attempted to identify the conserved portion by regional mapping of human DIA1 and ARSA using somatic cell hybrids segregating a human chromosome translocation t(15;22)(q14;q13.31). The results assign human DIA1 and ARSA to the distal sub-band of 22q13 (region 22q13.31 leads to qter). The locus for mitochondrial aconitase (ACO2) has been separated by the breakpoint from DIA1 and ARSA and is located more proximally.

Aconitate Hydratase↗
PubMed1981

Ocular and systemic responses to water soluble material derived from Cannabis sativa (marihuana).

A water soluble material, isolated from Cannabis sativa, has been tested in albino and pigmented rabbits and rhesus monkeys for both ocular and systemic effects. Intravenous administration produced a dose-related fall in intraocular pressure in both albino and pigmented rabbits with concentrations as low as 0.005 mg/animal being effective, but no response was found in monkeys. High concentrations (0.2 to 1 mg/animal) induced a hypertensive phase in intraocular pressure prior to the ocular hypotension; higher concentrations (2 or 5 mg/animal) also induced antidiuresis and general relaxation. Tachyphylaxis was found to repeated daily injections. Alpha and beta-adrenergic antagonists caused some reduction of the hypertensive phase but had no effect on the hypotensive phase. Superior cervical ganglionectomy did not influence the time course of the intraocular pressure response. Indomethacin inhibited the hypertensive intraocular pressure phase but was ineffective against the hypotensive phase. Systemic blood pressure was unchanged following intravenous administration of 0.2 mg material/animal. Aqueous tumor protein concentration was increased at both 1 and 6 hours after intravenous administration, becoming greater at the later time. Aqueous humor turnover rate was substantially reduced reaching a minimum 8.75 hours after administration. Topical administration was ineffective in eyes when the epithelium was removed in rabbits with and without pretreatment with aspirin. Neither gastric nor suppository administration of large quantities (10 mg or greater) of material had any influence on intraocular pressure.

Adrenergic alpha-Antagonists↗
PubMed1978

Quantitative analysis of high-resolution trypsin-giemsa bands on human prometaphase chromosomes.

We have constructed ideograms of human prometaphase chromosomes from synchronized and from standard 72-h lymphocyte cultures. G banding was achieved by a trypsin-Giemsa (or Wright's stain) method. In addition to light (white) and dark (black) bands, we have distinguished three different shades of grey. This distinction is essential for proper identification of the increasing number of bands displayed by high-resolution chromosomes. The relative amount of chromatin in each category of staining intensity has been calculated and expressed as 'light value.' The ideograms represent the maximal number of bands discernible with some consistency on prometaphase chromosomes, i.e., 721 euchromatic and 62 'variable' heterochromatic or heteromorphic bands. The ideograms are based on measurements. On selected printed copies of each chromosome derived from different cells and different individuals, the relative width of each band was measured in relation to the length of the respective chromosome arm. The measurements per chromosome were averaged and used for construction of the ideograms. The distance of each border between bands or sub-bands from the centromere has been calculated on a relative scale, with positions 0 at the centromere and 1.0 at the p terminus of q terminus. The numbering system for bands and sub-bands follows the Paris Conference (1971) recommendations.

Cell Cycle↗
PubMed1976

The distribution and characterization of group B streptococci in New York State.

Group B streptococcal isolates from bovine mastitis were classified according to the Lancefield typing scheme. Three types were found in New York State dairy herds; Ia, II and III. The distribution within these types varies from area to area, however, on a state-wide basis Ia is the most prevalent (69.6%) followed by type II (16.7%) and type III (10.1%). Within a single herd one type predominants with only slight incidence of other types. Attempts to determine distinguishing characteristics between isolates of human and bovine origin resulted in no entirely consistent differences.

Animals↗