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Biomedical subjects

D M Scott

Publications and source records attributed to D M Scott.

At least 19 recordsLinked to original sources
PubMed1995

Identification of a mouse male-specific transplantation antigen, H-Y.

The male-specific transplantation antigen, H-Y, causes rejection of male tissue grafts by genotypically identical female mice and contributes to the rejection of human leukocyte antigen-matched male organ grafts by human females. Although first recognized 40 years ago, the identity of H-Y has remained elusive. T cells detect several distinct H-Y epitopes, and these are probably peptides, derived from intracellular proteins, that are presented at the cell surface with major histocompatibility complex (MHC) molecules. In the mouse, the gene(s) controlling H-Y expression (Hya) are located on the short arm of the Y chromosome between the zinc-finger genes Zfy-1 and Zfy-2. We have recently identified Smcy, a ubiquitously expressed gene, in this region and its X-chromosome homologue, Smcx. Here we report that Smcy encodes an H-YKk epitope that is defined by the octamer peptide TENSGKDI: no similar peptide is found in Smcx. These findings provide a genetic basis for the antigenic difference between males and females that contributes towards a tissue transplant rejection response.

Amino Acid Sequence↗
PubMed1995

Pharmacists as nonprescription drug advisors.

This field study tested the ability of pharmacists to counsel patients with diabetes mellitus on the contraindicated use of a decongestant. The study was modeled after a 1969 study conducted by Knapp et al. Our simulation used a patient with diabetes who questioned pharmacists initially about proper insulin storage and then asked about the use of Contac (phenylpropanolamine) capsules, which carry a prominent label warning against use by diabetic patients. A research assistant, posing as the patient, interviewed pharmacists at 36 community pharmacies in a midwestern metropolitan area. Eleven of the pharmacists (30.5%) failed to warn the patient about the contraindication, compared with 83% in the earlier study.

Contraindications↗
PubMed1994

Process evaluation of Nebraska's Team Training Project.

BACKGROUND: A process evaluation of the Nebraska Drug Free School/Community Residential Team Training Project is described. This training project utilizes a "system approach" in the formation and implementation of localized strategic (action) plans targeting alcohol and other drug (AOD) abuse prevention. METHODS: In June of 1990, training participants completed a pre-post survey in conjunction with the four-day training. The majority of the participants (51.2%) were teachers, 19.2 percent were parents, 13.6 percent administrators, and 9.6 percent were counselors. RESULTS: Although the overall attitudes of the participants (N = 125) were positive initially, they became even more so by the end of the training (N = 121). Prior to training participants felt they could have a significant impact on their local AOD abuse problem, and this attitude became more positive by the completion of training (p < 0.05). CONCLUSIONS: The Nebraska team training process immerses team members in an active planning process allowing teams to develop a plan of action for their school and community. During this process, participants experience a positive growth in attitudes reflecting not only the training experience itself, but even more importantly their ability to meaningfully affect AOD abuse and related destructive behaviors in their homes, schools, and community.

Adult↗
PubMed1992

A new approach to the cloning of genes encoding T-cell epitopes.

The molecular structure of antigens recognized exclusively by T cells, such as minor histocompatibility antigens and some antigens that provoke autoimmune responses, has proved difficult to determine. Recently, several antigens induced on tumor cells by mutagen treatment have been cloned by transfection of genomic DNA libraries into P1.HTR cells, screening for antigen expression using T-cell clones, and subsequent recovery of the integrated DNA by cosmid rescue. We have modified this technique and have stably transfected P1.HTR cell lines with polyoma T antigen, which allows episomal replication of the shuttle vector, pCDM8. Using pCDM8-CAT constructs, we have determined the frequency of transfection and plasmid copies taken up per cell under optimal transfection conditions. Using a pCDM8 construct which expresses the tumor-specific antigen, P91A (pCDM8-tum-), that is recognized by a T-cell clone, we have found that cells transfected with this antigen can be recognized by the T-cell clone when they are present at only 1%-3% of a mixed population. Progeny of a single cell transfected with pCDM8-tum-: pCDM8-CAT at proportions of 1:10, 1:25, and 1:50 are recognized by the T-cell clone. Furthermore, Hirt extracted plasmid DNA from transfectants expressing the tum- antigen can be amplified in bacteria, transfected back into P1.HTR recipients, and recognized by the T-cell clone. This approach should enable reasonably rapid screening of cDNA libraries for even relatively low abundance messages encoding, for example, minor histocompatibility and alloantigens, and allow their subsequent cloning.

Animals↗
PubMed1992

The use of Ender nails in femoral shaft fractures: what are the remaining indications?

The use of Ender nails for the treatment of femoral shaft fractures has been described as technically easier and less time consuming than current intramedullary nailing techniques. We reviewed our results with unlocked Ender nails in 26 stable and 17 unstable fracture patterns an average of 3-4 years after injury. Because of continued instability, 42% of the stable and 76% of the unstable groups required adjunctive stabilization in the form of skeletal traction, a cast, or an external fixator. Additionally, nail migration and shortening and loss of motion at the knee were seen in 14 fractures in each group. Although two thirds of the patients with stable fracture patterns obtained good or excellent results, no outcome in the unstable group was rated excellent and only 19% were considered good. We therefore recommend that rigid locked intramedullary nails be used in femoral diaphyseal injuries. The use of Ender nails should be limited to stable fracture patterns and locked with screws or wires. They may be particularly useful for fractures in femora with small medullary canals (less than or equal to 8 mm), fractures below noncemented femoral prostheses, and fractures in young children requiring intramedullary stabilization without injuring the physeal plates.

Adolescent↗
PubMed1992

Factors affecting pharmacists' selection of rural or urban practice sites in Nebraska.

A questionnaire was used to determine why pharmacists in Nebraska chose urban or rural practice sites and to help the University of Nebraska College of Pharmacy encourage students to consider rural practice. Questionnaires were mailed to 1427 Nebraska pharmacists to gather data about their practice, job satisfaction, location of rearing, location of spouse's rearing, and prepharmacy and clerkship training. Usable responses were sorted into those from urban pharmacists (residing in Omaha and Lincoln and their suburban areas) and those from rural pharmacists (all others). Of the 689 usable responses, 315 (45.7%) were from urban pharmacists and 374 (54.3%) were from rural pharmacists. Of the rural pharmacists, 93% [corrected] grew up in communities of fewer than 100,000 people and 60% grew up in communities of fewer than 5,000 people. Respondents cited income potential, desirability of practice site, influence of spouse and family, and quality of children's schools as factors that most influenced their choice of practice site. Based on the survey results, the University of Nebraska College of Pharmacy took actions to recruit students from rural communities and increase students' exposure to rural practice settings. Pharmacists who were reared or trained in rural areas were more likely to practice in rural Nebraska than pharmacists who had only urban experience.

Career Choice↗
PubMed1991

An NMR spectroscopic characterization of a new epithelial cell line, TALH-SVE, with properties of the renal medullary thick ascending limb of Henle's loop.

NMR spectroscopy has been used to characterize a new renal cell line, TALH-SVE.1, which is derived from the medullary thick ascending limb of Henle's loop. From the 31P-NMR spectrum of a suspension of TALH-SVE cells using the chemical shift of the intracellular inorganic phosphate a value of 7.24 +/- 0.04 for the steady-state intracellular pH (pHi) was determined at pHo = 7.40. In addition, the 31P-NMR spectrum indicated rather high levels of UDPG, a finding confirmed by 1H-NMR spectra of perchloric acid extracts. The 1H-NMR data also demonstrate the presence of 'organic osmolytes' such as inositol, sorbitol, choline and glycerophosphoryl choline (GPC). 13C-NMR spectra of perchloric acid extracts of TALH-SVE cells incubated with [2-13C]- and [3-13 C]alanine were used to determine the relative influx in the Krebs cycle via pyruvate carboxylase (PCB) versus the influx via pyruvate dehydrogenase (PDH). The ratio was 0.41, while about 52% of all acetyl-CoA entering the Krebs cycle was unlabeled. 13C-NMR experiments also indicated that TALH-SVE cells lack gluconeogenic activity. The NMR study presented indicates that TALH-SVE cells possess metabolic pathways similar to those of the parental cells.

Alanine↗
PubMed1991

Studies on the phenotype and karyotype of immortalized rabbit kidney epithelial cell lines.

Differentiated mammalian cell lines can be isolated by immortalizing primary cells by transfection with DNA from plasmids containing sequences from SV40 early region. These cell lines show cytogenetic abnormalities but the degree of aneuploidy is considerably less than that observed in other established cell lines. No correlation was observed between the degree of differentiation of a clone and the extent of chromosomal damage.

Aneuploidy↗
PubMed1991

Performance of BOC Ohmeda Tec 3 and Tec 4 vaporisers following tipping.

The introduction of systems to facilitate the changing of vaporisers on the back bar of the anaesthetic machine has increased the risk of a vaporiser being tipped or inverted prior to attachment. The performance of three Ohmeda Tec 3 and three Ohmeda Tec 4 vaporisers following tipping to 30 degrees, 90 degrees and inversion to 180 degrees was measured using a calibrated Datex Capnomac AGM-103 analyser. Both types of vaporiser when switched off tolerated tipping and inversion without alteration of the anaesthetic concentration subsequently delivered. The same was true for the Tec 3 after tipping to 30 degrees and 90 degrees with the dial set at zero or above. However, after inversion of the Tec 3 vaporiser with the dial at zero or higher, the anaesthetic concentration delivered was much greater than shown on the dial, initially exceeding 12% for all agents. Should a Tec 3 vaporiser be inverted with the dial at any setting other than OFF, it is necessary to adequately flush it with fresh gas and check its output prior to use.

Anesthesia, Inhalation↗
PubMed1990

Modulation transfer functions: a comparison of the results of three methods.

Modulation transfer functions (MTFs) were measured with three different psychoacoustical paradigms in the same normal-hearing subjects. In the temporal-probe method, the threshold of a 4-ms probe tone (frequencies of 1000 and 4000 Hz) was measured at various envelope phases within a 100% sinusoidally amplitude-modulated (SAM) noise at modulation frequencies from 2 to 256 Hz. For the derived-MTF method, the threshold of a 500-ms tone at 1000 and 4000 Hz was measured in the same noise at the same modulation frequencies. For the modulation-detection paradigm, modulation thresholds were measured as a function of modulation frequency for bandpass filtered SAM noise centered at 1000 and 4000 Hz. MTFs with lowpass shapes were observed with all three methods. Differences were observed in the cutoff frequencies and/or attenuation rates when the data were fitted with lowpass filter transfer functions. Factors influencing those differences are discussed.

Adult↗
PubMed1989

Human cytomegalovirus and monocytes: limited infection and negligible immunosuppression in normal mononuclear cells infected in vitro with mycoplasma-free virus strains.

Human cytomegalovirus (HCMV) infection has previously been associated with the production of immunosuppression. The mechanism by which any such immunosuppressive effect might be mediated is unclear but previous work has implicated an effect of the virus on monocytes. We have attempted to characterize the immunosuppressive activity produced by in vitro infection of normal monocytes with HCMV strain AD169. We first examined the ability of HCMV AD169 and recent clinical isolates to infect normal peripheral blood mononuclear cells in vitro. We have found by immunofluorescence analysis that only a very limited number of peripheral blood mononuclear cells (0.2 to 0.5%) showed evidence of virus infection as demonstrated by expression of the major immediate early protein. We found that the inhibitory activity of supernatants of monocytes exposed to HCMV which suppressed mitogen-driven T cell responsiveness was associated with a protein of about 95K. Experiments to investigate the mechanism of action of this inhibitor suggested the possibility of mycoplasma contamination and we were subsequently able to isolate Mycoplasma hyorhinis from our AD169 virus stock. When a series of low passage clinical isolates of HCMV were examined for their ability to cause immunosuppression, there was a direct correlation between suppression and the presence of contaminating mycoplasmas. Using mycoplasma-free isolates of HCMV we could demonstrate no immunosuppressive effect on mitogen-mediated T cell proliferation of both unseparated human peripheral blood lymphocytes and nylon wool non-adherent T cells; these virus isolates also did not suppress accessory cell function or interleukin 1 production by monocytes infected in vitro. We conclude that the previously reported immunosuppressive effects of HCMV in vitro may be attributable to the presence of mycoplasmas and are unlikely to be due to expression of HCMV in monocytes. We suggest that mycoplasma contamination of isolates of HCMV may be a more extensive problem than is currently recognized.

Antibodies, Bacterial↗
PubMed1989

Rabbit urinary tamm-horsfall glycoprotein. Chemical composition and tentative carbohydrate structure.

The urinary Tamm-Horsfall protein (THP) is the major glycoprotein secreted by the mammalian kidney. We recently isolated and immortalized thick ascending limb of Henle cells from rabbit kidney, which produce Tamm-Horsfall protein in cell culture in vitro. In order to further study the yet undefined functional role and biosynthetic pathways of this protein, we first re-examined the chemical composition and the carbohydrate structure of rabbit urinary Tamm-Horsfall protein. Using precipitation with 0.58 mol/l NaCl a protein was isolated from rabbit urine which showed extensive microheterogeneity and had an average molecular mass of 95 kDa. Deglycosylation of the protein led to a loss of microheterogeneity and yielded a molecular mass of 58-60 kDa. Amino-acid analysis of the native and deglycosylated protein revealed a lower cysteine (20 mol/mol THP) and a higher histidine (20 mol/mol THP) content than described previously. Chemical analysis of the carbohydrates showed a high glucosamine (50 mol/mol THP), galactose (43 mol/mol THP), and mannose (24 mol/mol THP) content. The amount of sialic acid was 15 mol/mol THP. Using lectins to identify the structure of the carbohydrate chains it was shown that rabbit Tamm-Horsfall protein possesses complex-type oligosaccharide chains with terminal sialic acid, beta-galactose, and probably alpha-fucose and chains of the mucin type. These results indicate that some of the cysteine residues in the polypeptide chain of THP can be replaced by histidine, suggesting a role of some cysteins in metal binding rather than intramolecular stabilization.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1988

The effect of a native collagen gel substratum on the synthesis of collagen by bovine brain capillary endothelial cells.

Cultured capillary endothelial cells, derived from bovine brain, and maintained on a plastic substratum synthesized predominantly interstitial collagens of which approximately 75 per cent were secreted into the medium. When grown on a native hydrated collagen type I gel, although no marked alteration in the 'collagen synthetic pattern' was observed, the overall level of collagen synthesis was increased by approximately 100 per cent. More dramatic, however, was the alteration in the distribution of these molecules between medium and cell layer. Interstitial collagens produced by cells grown on collagen gels were almost exclusively associated with the cell layer or collagenous gel. These studies, thus, demonstrate that an extracellular matrix may exert a considerable influence on the cellular synthetic activities and possibly cellular polarity of capillary endothelial cells.

Animals↗
PubMed1988

Use of vancomycin and tobramycin polymethylmethacrylate impregnated beads in the management of chronic osteomyelitis.

Over the past several years there has been a growing interest in the use of locally implanted beads containing antibiotics for the treatment of chronic osteomyelitis. This method has been popularized in Europe and, with few exceptions, gentamicin has been the only antibiotic used. There have been only a few reports from the U.S. and there is little information regarding the pharmacokinetics of antibiotics used in this fashion. To our knowledge this is the first report using vancomycin. Three patients with chronic osteomyelitis were treated with vancomycin and/or tobramycin polymethylmethacrylate beads. These beads were extemporaneously compounded and implanted for up to six weeks. From the site of bead implantation local fluid aliquots were collected for the measurement of antibiotic concentrations. In two patients, initial tobramycin concentrations exceeded 400 mg/L. In one patient receiving vancomycin, initial localized concentrations were approximately 100 mg/L. In all three patients therapeutic concentrations of localized antibiotic were maintained with immeasurable systemic concentrations throughout the period of bead placement. Localized antibiotic therapy for the management of chronic osteomyelitis represents a potential therapeutic alternative to long-term parenteral therapy. Data presented here suggest that other antibiotics, such as vancomycin and tobramycin, can be used successfully in polymethylmethacrylate beads and provide preliminary facts for future investigations of such applications.

Adult↗
PubMed1987

Differentiation in vitro of primary cultures and transfected cell lines of epithelial cells derived from the thick ascending limb of Henle's loop.

The use of primary cell cultures derived from defined locations of the kidney has enabled the study of certain kidney cell type-specific characteristics under defined environmental conditions. The use of primary cell cultures, however, has a number of inherent disadvantages, many of which may be overcome by the use of differentiated cell lines of defined origin. In this paper I describe in detail an approach to: (a) the isolation and culture of primary cultures derived from the thick ascending limb of Henle's loop (TALH), and (b) the production of differentiated cell lines by the transfection of these primary cell cultures with early region SV40 virus genes. The characteristics of these cultures and other TALH-derived cell lines are described.

Animals↗