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Biomedical subjects

R Foster

Publications and source records attributed to R Foster.

At least 91 records · Page 5Linked to original sources
PubMed1990

Cell-type specific and differential regulation of the human metallothionein genes. Correlation with DNA methylation and chromatin structure.

The expression of three human metallothionein genes, MT-IIA, MT-IF, and MT-IG was studied in the human hepatoblastoma (HepG2), the hepatocarcinoma (Hep3B2), the embryonic kidney (Hek 293), and the lymphoblastoid-derived (Wi-L2) cell lines. The pattern of expression of each specific MT gene in response to various heavy metals was different among the four cell lines studied indicating differential regulation of MT gene expression. The MT-IF or MT-IG and the MT-IIA genes were regulated in a cell-type specific manner in response to heavy metals and dexamethasone, respectively. DNA methylation was shown to be correlated to cell-type specific regulation of MT gene expression since 5-azacytidine treatment resulted in the expression of the MT-IF and MT-IG genes in response to cadmium and zinc in Wi-L2 cells, of the MT-IIA gene in response to dexamethasone in Wi-L2 cells, and of the MT-IG in response to zinc and copper in Hek 293 cells. Furthermore, transfection studies indicated that all the trans-acting factors necessary for the expression of these genes were present and functional in Wi-L2 and Hek 293 cells. The differential level of expression of the MT-IF and MT-IG genes in response to heavy metals in the Hek 293 cell line was shown to be correlated to their chromatin structure.

Azacitidine↗
PubMed1990

Dryander of Marburg and the first textbook of neuroanatomy.

Born in Wetter, Germany, in 1500, Johannes Eichmann (Dryander) studied medicine and anatomy at the University of Paris from 1528 to 1534. In 1535, he was appointed professor of medicine at the University of Marburg. During the next year he held two public dissections, and in 1536 he was the author of the first text illustrating a Galenic dissection of the human brain. An expanded edition of this early book, the Anatomiae pars prior, was published in 1537. These texts represented an important transition from the dogma of medieval scholasticism to the precise observations of Vesalius. The books depicted the brain in eight figures, with four additional plates describing the skull, skull base, and cranial sutures. Detailed illustrations of the dura mater, cerebral cortex, and posterior fossa structures with clear, but inaccurate, relationship to the cranial nerves demonstrated Dryander's reliance on his own dissections. In 1542, he published a translated edition of Mundinus' anatomy. As was common at that time, the text plagiarized a portion of Vesalius' Tabulae sex, which resulted in the famous anatomist's anger. Despite this, Dryander continued to write on medical subjects as well as mathematics and astrology until his death in 1560. Because he was a progenitor of rational scientific thought, his earlier books represented an important advance in the progression to modern anatomic description and illustration.

Anatomy, Artistic↗
PubMed1990

Integration of nursing and business. Issues in curriculum development.

Foster and Boerstler look at the challenge of bringing integration into nursing service programs that combine nursing and business content. They examine capstone courses and internships among other strategies. They also give an interesting criterion of comparative advantage to judge where various content should be acquired.

Commerce↗
PubMed1990

Effects of lysostaphin on Staphylococcus aureus infections of the mouse mammary gland.

A 5 to 6 log10 reduction in the viable count of Staphylococcus aureus was produced in vitro with 10 micrograms lysostaphin ml-1 milk. Infusion of the lactating murine mammary gland with 10 micrograms lysostaphin, immediately following inoculation with 10(8) colony forming units of S aureus, resulted in a significant 2 to 3 log10 reduction in viable S aureus (P less than 0.02) within 30 minutes. Pre-infusion with 10 micrograms lysostaphin either immediately before or one hour before staphylococcal challenge reduced the recovery of S aureus by more than 6 log10 and greatly reduced pathological changes typical of S aureus mastitis. This clearly demonstrates that lysostaphin has considerable potential for the therapeutic or prophylactic control of staphylococcal mastitis.

Animals↗
PubMed1989

Roles of alpha-toxin and beta-toxin in virulence of Staphylococcus aureus for the mouse mammary gland.

Mutants of Staphylococcus aureus which fail to express alpha-toxin (Hly), beta-toxin (Hlb), or both have been constructed by site-specific mutagenesis. The virulence of the mutants was compared with that of wild-type toxigenic strains by intramammary inoculation of lactating mice. A bovine strain, M60, and a laboratory strain, 8325-4, caused acute mastitis and death within 48 h for 60% of the mice inoculated. Animals inoculated with Hly mutants also developed acute mastitis, but no deaths occurred. Comparisons of Hly- or Hlb-positive strains with the double mutation Hly Hlb showed that both toxins led to a significantly higher recovery of S. aureus from the gland 48 h postinfection. Histopathological examination of mammary glands showed that phagocytosis of bacteria occurred irrespective of toxigenicity, but toxigenic strains, particularly those which were Hly+, continued to multiply, invaded the interalveolar tissues, and produced severe lesions. Stimulation of an inflammatory response by inoculation of the mammary gland with endotoxin prior to challenge with S. aureus reduced recovery of the bacteria 10- to 100-fold and, under these conditions, neither alpha-toxin nor beta-toxin contributed significantly to growth and survival.

Animals↗
PubMed1989

Nucleotidylation, not phosphorylation, is the major source of the phosphotyrosine detected in enteric bacteria.

The majority of the phosphotyrosine recovered from partial acid hydrolysates of 32P-labeled Escherichia coli is derived from a single prominent protein. We show here by biochemical, genetic, and immunological criteria that this protein is actually glutamine synthetase adenylylated (not phosphorylated) at tyrosine. Furthermore, all of the phosphotyrosine detectable in partial acid hydrolysates of 32P-labeled Salmonella typhimurium was eliminated in a strain deficient in both glutamine synthetase and uridylyltransferase, an enzyme which uridylylates the regulatory protein PII at a tyrosine residue. These results suggest that protein-tyrosine phosphorylation represents a rare modification in eubacterial cells.

Electrophoresis, Gel, Two-Dimensional↗
PubMed1989

Calcium phosphate-mediated transfection alters metallothionein gene expression in response to Cd2+ and Zn2+.

The level of expression of a transfected metallothionein (MT)-IGcat fusion gene in response to cadmium differed from that of the endogenous MT-IG gene. Atomic absorption analysis indicated that the total cellular content of cadmium and zinc increased upon calcium phosphate-mediated transfection. Thus, changes in the influx/efflux of metals may regulate the level of MT gene expression.

Cadmium↗
PubMed1988

Structure and expression of the human metallothionein-IG gene. Differential promoter activity of two linked metallothionein-I genes in response to heavy metals.

The human metallothionein (MT)-IG gene (hMT-IG) is tandemly linked in a head-to-head fashion with the hMT-IF gene. The hMT-IG gene encodes a MT-I polypeptide and has a tripartite structure. The 5'-flanking region of the hMT-IG gene has a TATAA box, four GC motifs, and at least four metal responsive elements. The 3'-untranslated region has a variation of the polyadenylation signal, AATTAA, and the 3'-flanking region a YGTGTTYY RNA processing signal. This gene is expressed in hepatoma-derived cell lines (Hep G2 and Hep3B2) in response to the heavy metals (cadmium, copper, and zinc) but not to the glucocorticoid analogue dexamethasone. In contrast, the lymphoblastoid cell line (Wi-L2) does not express the hMT-IG gene. These results suggest that the hMT-IG gene is regulated differentially and in a cell type-specific manner. Transient expression studies of the chloramphenicol acetyltransferase (CAT) gene under the transcriptional control of either the hMT-IG or hMT-IF promoter in Hep G2 cells has demonstrated that both promoters contain all the necessary cis-acting elements to elicit a similar pattern of heavy metal inducibility. However, the hMT-IG promoter in all instances is five times more active than the hMT-IF promoter. The differences in promoter activity of these genes could possibly be due to inherent differences in their basal level regulatory sequences. The expression of MT-IGcat in transfected Wi-L2 cells demonstrates that the hMT-IG promoter is not cell type-specific.

Base Sequence↗
PubMed1988

Expression of heat stress proteins by human periodontal ligament cells.

The purpose of the present report was to document the stress response produced by physical and chemical abuses to human periodontal ligament cells, and to review some of the known functions of stress response proteins produced as a result of such treatments. For these studies human PDL cells were exposed to sublethal challenges of 43 degrees C heat, sodium arsenite and the amino acid analog L-azetidine-2-carboxylic acid (AZC). The cells were labelled with [35S]-methionine and the proteins produced were examined by autofluorography of SDS-PAGE gels. Heat challenges were shown to induce hsps with an apparent mol. wts. of 90K, 68-72K, 41-47K, and 36 K. Arsenite-treated cells produced similar hsps including a 30k protein not produced by other forms of stress. AZC treatment resulted in the production of apparent functionless hsps with apparent molecular weights of 90,000, 72,000, 68,000 and 36,000. The function of these proteins and their possible role in periodontal disease is discussed.

Arsenic↗
PubMed1987

Structure and expression of the human metallothionein genes.

The human metallothioneins are represented by a multigene family consisting of about 14 members. A number of MT-like genes have been isolated from a human genomic library and in this report, four MT genes have been characterized. Our results show that two of these genes represent the MT-I and MT-II processed genes. The other two genes (MT-IF and MT-IG) are functional members of the MT-I gene family. The amino acid sequence encoded by the MT-IF and MT-IG genes differ from the amino acid sequences of the published MT-I proteins at few positions. The 5'-flanking region of these genes contain metal responsive elements. Our studies show that the MT-IF and MT-IG genes are differentially regulated in two human hepatoma cell lines, HepG2 and Hep3B2, and a human lymphoblastoid cell line, WI-L2 in response to the heavy metals cadmium, zinc and copper, and glucocorticoids. In addition, these genes also show cell-type specific expression.

Amino Acid Sequence↗
PubMed1987

A review of clinical experience with oxamniquine.

Oxamniquine has now been in general use for 11 years for the treatment of schistosomiasis mansoni. Dosage varies with the geographical origin of the parasites due to different susceptibilities of local strains, and the appropriate regimen can be expected to cure over 80% of patients and reduce egg excretion in others by over 90%. The drug has been used safely in all stages of the disease. Some late-stage and complicated forms have shown clinical improvement, and prognosis has been improved in all by the removal of the causative organisms. Toleration is usually good with side effects limited to a mild, transient dizziness. Neuropsychiatric disturbances have been recorded in a small number of patients, and care should be taken in treating subjects with a history of such disorders. Nevertheless, these effects have not limited use of the drug which has been used widely for the field treatment of several million people in rural communities. These schemes have led to reductions in incidence, prevalence and the occurrence of hepatosplenic involvement.

Central Nervous System Diseases↗
PubMed1987

Retroperitoneal fibrosis and nonmalignant ileal carcinoid.

The carcinoid syndrome and fibrosis are unusual but identifiable disease processes. We report a rare case of retroperitoneal fibrosis associated with an ileal carcinoid in the absence of metastatic disease. The literature is reviewed.

Carcinoid Tumor↗
PubMed1987

Osmotic significance of glycerol accumulation in exponentially growing yeasts.

Natural-abundance 13C-nuclear magnetic resonance spectroscopy has shown glycerol to be the major osmotically significant low-molecular-weight solute in exponentially growing, salt-stressed cells of the yeasts Saccharomyces cerevisiae, Zygosaccharomyces rouxii, and Debaromyces hansenii. Measurement of the intracellular nonosmotic volume (i.e., the fraction of the cell that is osmotically unresponsive) by using the Boyle-van't Hoff relationship (for nonturgid cells, the osmotic volume is directly proportional to the reciprocal of the external osmotic pressure) showed that the nonosmotic volume represented up to 53% of the total cell volume; the highest values were recorded in media with maximum added NaCl. Determinations of intracellular glycerol levels with respect to cell osmotic volumes showed that increases in intracellular glycerol may counterbalance up to 95% of the external osmotic pressure due to added NaCl. The lack of other organic osmotica in 13C-nuclear magnetic resonance spectra indicates that inorganic ions may constitute the remaining component of intracellular osmotic pressure.

Glycerol↗
PubMed1986

A cytokinin mutant derived from cultured tobacco cells.

Tissues cultured from the leaf lamina of wild-type Nicotiana tabacum L. cv. "Havana 425" plants require an exogenous source of cytokinin for rapid growth. In contrast, leaf tissues of plants heterozygous or homozygous for the partially dominant, monogenic habituated leaf (H1-1) trait, exhibit a cytokinin-autotrophic phenotype in culture. Here we show that the H1 trait can arise in culture. Cytokinin autotrophic variants were obtained by culturing wild-type tissues of leaf lamina successively on media containing reduced concentrations of the cytokinin, kinetin. Plants regenerated from clones of these variants exhibited the H1 phenotype, which segregated in breeding tests as expected for a dominant, monogenic trait. This trait, designated H1-2, is inherited at a different locus than the H1-1 trait described earlier. Our results show that cytokinin mutants can arise in cell culture and that at least two genes regulate the cytokinin requirement of cultured tobacco tissues.

Cell Division↗
PubMed1986

Transdetermination of plant cells.

Tissues derived from the leaf lamina of Nicotiana tabacum L. cv. Havana 425 plants require cytokinin for continuous proliferation in culture, whereas tissues derived from the cortex of the stem are cytokinin autotrophic. Both phenotypes persist when the two types of cells are cloned, indicating that leaf- and cortex-derived cells are determined to express different cytokinin requirements in culture. We showed that cultures derived from leaf and cortex tissues of plants regenerated from cloned leaf and cortex cells exhibit the cytokinin requirement of comparable tissues of seed-grown plants. This provides direct evidence that plant cells can undergo transdetermination and that this process has an epigenetic basis.

Cell Differentiation↗