Search PubMed⌕ Search

Biomedical subjects

S D Jones

Publications and source records attributed to S D Jones.

17 recordsLinked to original sources
PubMed1992

Molecular cloning of a cDNA encoding aspartate aminotransferase-P2 from lupin root nodules.

Two isoenzymic forms of aspartate aminotransferase are present in the plant fraction of developing lupin root nodules. One of these forms, aspartate aminotransferase-P2 (AAT-P2), increases dramatically with the onset of biological nitrogen fixation and is associated with the assimilation of ammonia by the plant in the Rhizobium-legume symbiosis. A day 18 lupin nodule cDNA library in the lambda ZapII vector was immunoscreened with a monoclonal antibody specific for AAT-P2 and yielded two near-full-length 1700 bp clones. These clones were sequenced. Amino acid sequences from three peptides derived from immunopurified AAT-P2 were aligned, and showed 100% homology with the amino acid sequence deduced from the cDNA clones. The DNA sequence showed 50% homology with AAT sequences from a range of animal sources. Conversion of the clones to the phagemid form allowed their expression in Escherichia coli where both exhibited enzyme activity that could be immunoprecipitated with AAT-P2-specific monoclonal antibodies. Western blot analysis revealed protein moieties with molecular masses of 39, 43, 45 and 55 kDa. The 5' end of the clones coded for a hydrophobic leader sequence of about 50 amino acids indicative of a targeting sequence and consistent with the plastid localisation of nodule AAT-P2.

Amino Acid Sequence↗
PubMed1992

A novel 7-nucleotide motif located in 3' untranslated sequences of the immediate-early gene set mediates platelet-derived growth factor induction of the JE gene.

A cohort of the serum and growth factor regulated immediate-early gene set is induced with slower kinetics than c-fos. Two of the first immediate-early genes characterized as such, c-myc and JE, are contained within this subset. cis-acting genomic elements mediating induction of the slower responding subset of immediate-early genes have never been characterized. Herein we characterize two widely separated genomic elements which are together essential for induction of the murine JE gene by platelet-derived growth factor, serum, interleukin-1, and double-stranded RNA. One of these elements is novel in several regards. It is a 7-mer, TTTTGTA, found in the proximal 3' sequences downstream of the JE stop codon. The 3' element is position dependent and orientation independent. It does not function in polyadenylation, splicing, or destabilization of the JE transcript. Copies of the 7-mer or its inverse are found at comparable 3' sites in 25 immediate-early genes that encode transcription factors or cytokines. Given its general occurrence, the 7-mer may be a required cis-acting control element mediating induction of the immediate-early gene set.

3T3 Cells↗
PubMed1992

HA disagreement.

Explore the source record for details and available documents.

Dental Implants↗
PubMed1992

Extracellular calcium mimics the actions of platelet-derived growth factor on mouse fibroblasts.

Microprecipitates of calcium phosphate (CaPO4) can substitute for platelet-derived growth factor (PDGF) to stimulate the growth of cultured 3T3 cells. In two-part complementation assays, CaPO4 behaves as a PDGF-like "competence factor"--that is, the mitogenic response to CaPO4 is enhanced synergistically by "progression factors" contained in platelet-poor plasma. In studies described here, we show that early cytoplasmic and intranuclear events in the mitogenic response to CaPO4 are equivalent to those induced by PDGF. However, no net increase in tyrosine kinase activity of either the PDGF-alpha or PDGF-beta receptor is seen following exposure to CaPO4. Our data suggest that calcium acts within the cell, regulating events which normally proceed from activation of PDGF receptors. Alternatively, microprecipitates of CaPO4 could act externally by activating a growth factor receptor which escapes detection with available reagents.

3T3 Cells↗
PubMed1989

Sustained-release theophylline pharmacokinetics in the cat.

Theophylline was administered in a three-way crossover design study to six cats intravenously (Aminophylline USP, Invenex Laboratories, Chagrin Falls, OH) and orally as two sustained-release formulations (Slo-bid Gyrocaps (SB), William H. Rorer, Inc., Fort Washington, PA; Theo-Dur Tablets (TD), Key Pharmaceuticals, Miami, FL). Values were determined for mean residence time (SB = 19.4 +/- 3.2 h; TD = 15.8 +/- 4.8 h), mean absorption time (SB = 8.0 +/- 2.3 h; TD = 4.8 +/- 2.3 h), absolute bioavailability (SB = 82 +/- 27%; TD = 76 +/- 38%), and time to peak plasma concentrations (SB = 8 h; TD = 8 h). After normalization to a dose of 25 mg/kg, the average peak plasma concentrations were also predicted (SB = 10.5 +/- 3.4 micrograms/ml; TD = 14.3 +/- 6.7 micrograms/ml). Slo-bid was predicted to provide the least peak:trough fluctuation in theophylline concentrations. Slo-bid and Theo-Dur appear to have pharmacokinetic characteristics which, if given once-daily, would maintain plasma theophylline concentrations of 5-20 micrograms/ml in the cat.

Animals↗
PubMed1989

Evidence for a novel signal transduction pathway activated by platelet-derived growth factor and by double-stranded RNA.

Platelet-derived growth factor (PDGF) and the synthetic double-stranded RNA poly(I).poly(C) [poly(I.C)] stimulate transcription of the JE gene in BALB/c-3T3 fibroblasts. The response of JE to poly(I.C) does not appear to be channeled through any known component of the PDGF receptor signal transduction apparatus. In addition, JE sequences upstream of the transcription start site are devoid of previously identified poly(I.C)-responsive elements, such as those found in the beta-interferon gene. These data suggest that a novel signal transduction pathway regulates the JE response to PDGF and double-stranded RNA. The c-myc and c-fos proto-oncogenes also respond to this pathway but with poor efficiency. However, this pathway operates very efficiently on other PDGF-inducible genes that encode the secretory proteins KC and M-CSF.

1-Phosphatidylinositol 4-Kinase↗
PubMed1989

Educating women about the importance of breast screenings: the nurse's role.

Breast cancer is one of the leading causes of cancer deaths among women in the United States. Although it has been well documented that the incidence of mortality from this disease can be reduced through early detection, only a small percentage of women actually comply with breast screening recommendations. Nurses are in an excellent position to educate women on the importance of early detection of breast cancer. This article discusses the motivating and inhibiting factors that influence a woman's decision to participate in breast screening activities, and suggestions are made for designing educational programs that take these factors into account. Emphasis is placed on the nurse's role in educating patients and the public about the importance of breast cancer screenings.

Adult↗
PubMed1988

Tissue-integrated implants for the partially edentulous patient.

Patients who have been dissatisfied with removable prostheses and have sufficient alveolar or cortical bone may be appropriate candidates for osseointegrated implants. This article demonstrates the clinical application of osseointegrated implants for the partially edentulous patient as a viable alternative treatment.

Dental Implantation, Endosseous↗
PubMed1988

Platelet-derived growth factor generates at least two distinct intracellular signals that modulate gene expression.

Regulation of the genes by PDGF has some common features. All are primary response genes, and they can still be expressed in the presence of cycloheximide (Cochran et al. 1983; Kelly et al. 1983; Kruijer et al. 1984; Lau and Nathans 1985). In fact, many of the genes are superinduced when cells are treated with growth factors plus cycloheximide (Greenberg et al. 1986). The genes that have been characterized all contain a sequence motif in their 3'-noncoding sequences that appears to make the message labile (Meijlink et al. 1985; Treisman 1985; Shaw and Kamen 1986). All competence genes so far examined are controlled at least in part at the level of transcription (Cochran et al. 1983; Edwards et al. 1985; Almendral et al. 1988). Differences in regulation of the genes include variations in the time course of induction, ranging from 10 minutes to over 4 hours, and differences in the persistence of the mRNAs after their synthesis (Cochran et al. 1983; Muller et al. 1984; Lau and Nathans 1987). The data presented in this paper strongly suggest that multiple, distinct intracellular signals that lead to the expression of multiple genes are generated when cells are treated with growth factors such as PDGF. The variation in the time course of induction of PDGF-inducible genes suggests several models of signal transduction. Four such models are presented in Figure 5. One possibility (Fig. 5A) is that one signal is generated by the interaction of PDGF with its receptor and that this signal activates the very early genes, such as c-fos.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Use of mononuclear leukocyte insulin receptor characteristics as predictors of carcass composition in heifers and steers.

Total insulin specific binding (IB) and the number and affinity of insulin receptors on mononuclear leukocytes (MNL) were used to predict carcass composition of heifers and steers. Dependent variables were kidney fat, body cavity fat, s.c. fat, intermuscular fat, lean and bone. Independent variables were parameters that could be measured on the live animal, including insulin receptor characteristics, age, shrunk weight, breed and carcass s.c. rib fat thickness (SUB). All carcass fat characteristics and IB were greater for heifers than for steers, but the ability to predict either heifer or steer carcass fat characteristics was not improved by inclusion of IB in prediction equations. However, the number of low-affinity insulin receptors on MNL contributed significantly to the prediction of all heifer carcass characteristics except bone. Carcass s.c. rib fat thickness also entered the prediction equations for all heifer carcass characteristics except kidney fat. In the prediction of heifer kidney fat, the only significant independent variable was the number of low-affinity insulin receptors on MNL (R2 = .38). Carcass characteristics of steers were better predicted by SUB than were heifer carcass characteristics, and insulin receptor characteristics, when added to steer equations that contained SUB, improved R2 by .10 or less. Our results suggest that insulin receptor characteristics will be most useful in the prediction of carcass characteristics of heifers where there is a poor relationship between quantity of s.c. fat and other carcass fat depots.

Adipose Tissue↗
PubMed1988

Proliferation kinetics of a murine fibrosarcoma during fractionated irradiation.

Accelerated growth of tumor clonogens during the course of fractionated irradiation has been considered one of the major causes of radiation treatment failure. Alterations in clonogen growth rate could occur through three basic mechanisms: changes in cell-loss factor, changes in cell-cycle time, and recruitment of previously quiescent cells into the proliferative pool. This study was designed to assess changes in the cell-cycle time of clonogens of a murine fibrosarcoma during fractionated irradiation using an artificial pulmonary micrometastasis model. Lung colonies of various ages (4 h, 1 day, or 4 days) were exposed to single doses of irradiation ranging from 5-13 Gy; the fraction of surviving colonies was used to determine the preirradiation growth kinetics. The growth kinetics during fractionated irradiation was derived from colony-survival data of 4-day-old micrometastasis exposed to single doses or to 2, 5, 9, and 15 fractions separated by 4, 12, or 24-h intervals. The size of dose fractions used ranged from 1.7 to 14 Gy. The estimated clonogen doubling times before irradiation and during overall treatment periods of up to 14 days were 0.71 and 1.1 days, respectively. This significant (P less than 0.0001) increase in the doubling time was most likely a consequence of lengthening of the overall cell-cycle time of the clonogens by radiation-induced division delay. This observation suggests that accelerated growth, when it occurs in some tumors during fractionated treatment, is the result of a decreased cell-loss factor or recruitment of quiescent cells, but not a shortening of the cell-cycle time of the clonogens.

Animals↗
PubMed1987

The immunoglobulin octanucleotide: independent activity and selective interaction with enhancers.

The thymidine kinase (tk) promoter of herpes simplex virus includes an octanucleotide sequence motif (ATTTGCAT) that is also an essential component of immunoglobulin kappa gene promoters. In the absence of an enhancer, tk promoter derivatives that contain this element support a higher rate of transcription than those that lack it. The action of the kappa enhancer augments that of the octanucleotide in B lymphoid cells; when both elements are present, tk promoter activity is increased by more than an order of magnitude. In contrast, the presence of the octanucleotide in this promoter markedly reduces its response to a nonimmunoglobulin enhancer. These results suggest that the octanucleotide may mediate a selective interaction among promoters and enhancers.

DNA, Viral↗
PubMed1986

The effects of two shipping treatments on the carcass characteristics of bulls implanted with zeranol and unimplanted steers.

A total of 144 male crossbred calves were allocated to four management treatments (bulls; steers; bulls implanted with zeranol at 100 d of age and re-implanted at 69, 93 and 56 d thereafter; bulls implanted with zeranol at 168 d of age and re-implanted at 93 and 56 d thereafter), and two pre-slaughter shipping treatments (minimum pre-slaughter stress with cattle shipped and slaughtered within 4 h of leaving the feedlot pen; moderate pre-slaughter stress with cattle mixed, trucked 160 km and slaughtered up to 24 h of leaving the feedlot pen) in a 4 X 2 factorial arrangement. Management treatment had no significant effect on carcass pH (45 min), carcass muscle temperature (45 min), or peak shear-force of cooked longissimus muscle. Steers had significantly lower dressing percentage, warm-carcass weight, hide weight and carcass-lean content, but higher marbling score, fat thickness and intramuscular-fat content than all treatments with bulls. Minimum pre-slaughter stress resulted in significantly lower dressing percentage, warm-carcass weight, and carcass pH (45 min), but generally had no effect on carcass tissue-yield measurements compared with the moderate stress treatment. Implanted bulls produced carcasses with significantly darker meat, higher 24-h pH and lower meat expressible juice than bulls and castrates for the moderate pre-slaughter stress treatment. These results provide evidence that zeranol implantation in bulls had a minor influence on carcass characteristics, and did not reduce the incidence of dark-cutting carcasses in young bulls subjected to moderate pre-slaughter shipping stress.

Animals↗
PubMedDate not supplied

Evaluation of a commercial process for collection and cooling of beef offals by a temperature function integration technique.

The hygienic adequacy of a commercial process for the collection and cooling of beef offals was assessed by a temperature function integration technique. The diverse operations for collection of offals were inspected. The rates of product movement through those operations, and the temperatures of products at the time of their being packed, were determined. From that information, four of the nine product types were selected for examination of their temperature histories during the assembly and cooling of the cartoned products. The products selected encompassed product at near-body and near-air-ambient temperatures at the time of packaging, product in the largest and smallest cartons used in the process, and product with relatively short and long residence times in an unchilled carton stack assembly area. Twenty-one temperature histories were collected for each of the products, and the possible proliferation of an indicator organism, Escherichia coli, calculated for each temperature history. The results were assessed against a temperature function integration criterion derived from studies of beef carcass and cartoned meat cooling processes. Products packaged at near-ambient temperature readily met with the criterion, but products packed at near-body temperatures did not comply. The latter non-compliance was extreme for product packaged in large cartons. However, the principal cause of non-compliance was identified as highly variable cooling conditions in the carton freezing facility. A brief survey of air speeds and temperatures within that facility indicated means by which product cooling could be better controlled.

Animals↗