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Biomedical subjects

K Hunter

Publications and source records attributed to K Hunter.

At least 37 records · Page 2Linked to original sources
PubMed1999

Stable and efficient gene transfer into the mutant retinal pigment epithelial cells of the Mitf(vit) mouse using a lentiviral vector.

PURPOSE: The purpose of the present study was to test whether a lentiviral vector encoding the marker lacZ gene under the control of the human CMV promoter would stably infect a significant number of RPE cells in the vitiligo mouse. This mouse harbors a mutation in the microphthalmia gene in RPE cells that leads to slow progressive photoreceptor cell degeneration. METHODS: Concentrated lentiviral vector HR'CMVlacZ was injected intravitreally into newborn vitiligo mice. Mice were sacrificed at various time points up to two months post-injection and eyes were processed histochemically to detect lacZ expression. RESULTS: The lentiviral vector infected predominantly the RPE and resulted in lacZ expression in numerous RPE cells at all times analyzed. CONCLUSIONS: LacZ expression in vitiligo RPE cells appeared to be stable for a period of at least two months. These results raise the possibility of using a similar lentiviral vector for introduction of a correct copy of the microphthalmia cDNA into the RPE that may ultimately rescue photoreceptor cells in this mutant mouse.

Animals↗
PubMed1999

Genetic regulation of long-term nonprogression in E-55+ murine leukemia virus infection in mice.

Certain inbred mouse strains display progression to lymphoma development after infection with E-55+ murine leukemia virus (E-55+ MuLV), while others demonstrate long-term nonprogression. This difference in disease progression occurs despite the fact that E-55+ MuLV causes persistent infection in both immunocompetent BALB/c-H-2(k) (BALB.K) progressor (P) and C57BL/10-H-2(k) (B10.BR) long-term nonprogressor (LTNP) mice. In contrast to immunocompetent mice, immunosuppressed mice from both P and LTNP strains develop lymphomas about 2 months after infection, indicating that the LTNP phenotype is determined by the immune response of the infected mouse. In this study, we used bone marrow chimeras to demonstrate that the LTNP phenotype is associated with the genotype of donor bone marrow and not the recipient microenvironment. In addition, we have mapped a genetic locus that may be responsible for the LTNP trait. Microsatellite-based linkage analysis demonstrated that a non-major histocompatibility complex gene on chromosome 15 regulates long-term survival and is located in the same region as the Rfv3 gene. Rfv3 is involved in recovery from Friend virus-induced leukemia and has been demonstrated to regulate neutralizing virus antibody titers. In our studies, however, both P and LTNP strains produce similar titers of neutralizing and cytotoxic anti-E-55+ MuLV. Therefore, while it is possible that Rfv3 influences the course of E-55+ MuLV infection, it is more likely that the LTNP phenotype in E-55+ MuLV-infected mice is regulated by a different, closely linked gene.

Animals↗
PubMed1998

Tissue protein synthesis rates in critically ill patients.

OBJECTIVES: The aims of this study were to simultaneously determine the in vivo rates of protein synthesis in skeletal muscle, peripheral blood lymphocytes, and serum albumin in critically ill patients; to establish whether a relationship between the responses of these tissues could be observed; and to demonstrate if a protein synthesis pattern characteristic of critical illness exists. DESIGN: Descriptive study. SETTING: Intensive care unit of a 1000-bed university hospital. PATIENTS: Fifteen patients treated in the intensive care unit. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Rates of tissue protein synthesis were determined in vivo once during the course of critical illness, using the flooding method with L-(2H5)phenylalanine. Protein synthesis in muscle was 1.49 +/- 0.16%/day; in circulating lymphocytes (i.e., mononuclear cells), protein synthesis was 11.10 +/- 1.82%/day. Albumin synthesis was 12.81 +/- 1.23%/day when expressed as the fractional rate, and was 184 +/- 19 mg/kg/day when expressed as the absolute rate. CONCLUSIONS: The individual tissues responded differently to trauma, and showed a wide range of values. The responses were not significantly correlated with each other and no pattern of tissue protein synthesis characteristic of critical illness was observed. However, both muscle protein and albumin synthesis rates correlated with metabolic status and clinical indices of the severity of illness.

Adult↗
PubMed1997

High-resolution linkage map of mouse chromosome 13 in the vicinity of the host resistance locus Lgn1.

Natural resistance of inbred mouse strains to infection with Legionella pneumophila is controlled by the expression of a single dominant gene on chromosome 13, designated Lgn1. The genetic difference at Lgn1 is phenotypically expressed as the presence or absence of intracellular replication of L. pneumophila in host macrophages. In our effort to identify the Lgn1 gene by positional cloning, we have generated a high-resolution linkage map of the Lgn1 chromosomal region. For this, we have carried out extensive segregation analysis in a total of 1270 (A/J x C57BL/6J) x A/J informative backcross mice segregating the resistance allele of C57BL/6J and the susceptibility allele of A/J. Additional segregation analyses were carried out in three preexisting panels of C57BL/6J x Mus spretus interspecific backcross mice. A total of 39 DNA markers were mapped within an interval of approximately 30 cM overlapping the Lgn1 region. Combined pedigree analyses for the 5.4-cM segment overlapping Lgn1 indicated the locus order and the interlocus distances (in cM): D13Mit128-(1.4)-D13Mit194-(0.1)-D13Mit147-(0.9)-D13 Mit36-(0.9)-D13Mit146-(0.2)-Lgn1/D13Mit37-(1.0)- D13Mit70. Additional genetic linkage studies of markers not informative in the A/J x C57BL/6J cross positioned D13Mit30, -72, -195, and -203, D13Gor4, D13Hun35, and Mtap5 in the immediate vicinity of the Lgn1 locus. The marker density and resolution of this genetic linkage map should allow the construction of a physical map of the region and the isolation of YAC clones overlapping the gene.

Animals↗
PubMed1997

Application of interspersed repetitive sequence polymerase chain reaction for construction of yeast artificial chromosome contigs.

Construction of physical maps across candidate regions is one of the rate-limiting steps of positional cloning projects. To date, most physical maps have been constructed by polymerase chain reaction (PCR)-based sequence-tagged site (STS) content mapping. While effective, this technique has a number of disadvantages including problems with yeast artificial chromosome (YAC) chimerism, the time and effort required to generate new STSs from YAC ends, the cost of primer synthesis for large contiging projects, and the time, effort, and expense necessary for screening each STS in the two-tiered hierarchical YAC library screening format. An alternative strategy, interspersed repetitive sequence (IRS) PCR genomics, alleviates many of these constraints. Clonal overlap is detected by hybridization of individual IRS-PCR products to IRS-PCR product pools of the three-dimensional coordinate pools of YAC libraries in dot-blot format. Entire libraries can be screened in a single step, and multiple libraries can be screened simultaneously. Cloning YAC fragments, sequencing, and primer generation are eliminated, increasing the efficiency of contig construction and reducing the expense. In addition, the genomic location of the individual IRS-PCR products can also be simultaneously determined by screening either interspecific backcrosses or radiation hybrid panels, in dot-blot format, confirming contig extension in the region of interest.

Animals↗
PubMed1996

A multivariate analysis of evoked responses in EEG and MEG data.

This paper presents a multivariate analysis of evoked responses and their spatiotemporal dynamics as measured with electro- or magnetoencephalography. This analysis uses standard techniques (ManCova) to make possible statistical inference about differential responses, after the data have been transformed using singular value decomposition. The generality of this approach is limited only by the assumptions implicit in the general linear model and can range from simple analyses like Hotelling's T2 test (in comparing evoked responses among different conditions) to complex analyses of a multivariate regression type (e.g., characterizing the response components associated with a behavioral or psychophysical parameter). To illustrate the technique we have characterized time-dependent changes (both within and between trials) in magnetic fields, evoked by self-paced movements. Our illustrative analysis showed that movement-evoked components were less prone to adaptation than premovement components, suggesting that functionally distinct (preparatory and early executive) biomagnetic signals show differential adaptation.

Analysis of Variance↗
PubMed1996

"Don't think zebras": uncertainty, interpretation, and the place of paradox in clinical education.

Working retrospectively in an uncertain field of knowledge, physicians are engaged in an interpretive practice that is guided by counterweighted, competing, sometimes paradoxical maxims. "When you hear hoofbeats, don't think zebras," is the chief of these, the epitome of medicine's practical wisdom, its hermeneutic rule. The accumulated and contradictory wisdom distilled in clinical maxims arises necessarily from the case-based nature of medical practice and the narrative rationality that good practice requires. That these maxims all have their opposites enforces in students and physicians a practical skepticism that encourages them to question their expectations, interrupt patterns, and adjust to new developments as a case unfolds. Yet medicine resolutely ignores both the maxims and the tension between the practical reasoning they represent and the claim that medicine is a science. Indeed, resolute epistemological naivete is part of medicine's accommodation to uncertainty; counterweighted, competing, apparently paradoxical (but always situational) rules enable physicians simultaneously to express and to ignore the practical reason that characterizes their practice.

Art↗
PubMed1996

Generation and mapping of Mus spretus strain-specific markers for rapid genomic scanning.

We describe here a set of genetic markers, based on IRS-PCR amplification difference, that are specifically designed for efficient, high throughput genetic mapping in [(M. domesticus x wild-derived) F1 x M. domesticus] interspecific backcrosses. 146 new genetic loci have been mapped, and strain distribution for these markers has been determined in 96 mouse strains. 103 (81%) of 127 tested markers are present only in one or more wild-derived strains, but absent in 76 other commonly used strains, demonstrating their utility in a variety of mouse pair combinations. Because of the ease of genotyping with this marker set, rapid genome scans for complex genetic trait loci involving crosses between wild-derived strains and other commonly used strains can now be carried out efficiently with large numbers of animals.

Animals↗
PubMed1996

Protein synthesis rates of skeletal muscle, lymphocytes, and albumin with stress hormone infusion in healthy man.

The rate of protein synthesis was assessed in muscle, lymphocytes, and albumin in healthy volunteers administered an infusion of 6.0 micrograms cortisol +3.0 ng glucagon +0.5 nmol epinephrine min-1.kg-1. Protein synthesis in muscle tissue was not sensitive to the immediate effects of hormone infusion, but decreased significantly by 18 hours after the infusion had ceased (1.77% +/- 0.12% per day v 1.29% +/- 0.10%, P < .05). The rate of protein synthesis in lymphocytes was acutely sensitive to the effect of the hormone infusion, decreasing from 7.15% +/- 1.02% per day to 2.47% +/- 0.5% (P < .05). However, measurements made 18 hours after the end of the hormone infusion indicated that lymphocyte protein synthesis returned to the preinfusion rates. The rate of albumin synthesis was unaltered during infusion of the stress hormones, but was significantly increased when measured 18 hours after ending the hormone infusion (6.84% +/- 0.43% per day v 7.99% +/- 0.45%, P < .05). Thus, tissues respond differently to stress hormone infusion, demonstrating the importance of studying multiple organ systems when assessing the regulation of protein metabolism.

Adult↗
PubMed1996

Genetic mapping of a pulmonary adenoma resistance (Par1) in mouse.

Lung cancer, a major cause of death in the Western world, has a poor prognosis. So far, therapeutic strategies have had only a limited effect. Lung cancer risk is strongly associated with cigarette smoking and lung cancer pedigrees are rare. However, a possible polygenic nature of inherited predisposition to this cancer has been envisaged. Mouse inbred strains with inherited predisposition and resistance to lung cancer provide an important tool for the dissection of the genetics of this complex disease. The A/J strain carries the pulmonary adenoma susceptibility 1 (Pas1) locus and develops many lung tumours. We have mapped the M. spretus-derived locus that strongly resists the lung tumorigenesis in Pas1/+ mice. This locus, pulmonary adenoma resistance 1 (Par1) maps to mouse chromosome 11, near the Rara locus, with a lod score of 5.3. In Pas1/+ mice Par1 accounts for 23% of the phenotypic variance and 10 fold reduction in total tumour volume. These results provide evidence for a major resistance locus affecting the expression of an inherited predisposition to lung cancer.

Adenoma↗
PubMed1995

Efficient high-resolution genetic mapping of mouse interspersed repetitive sequence PCR products, toward integrated genetic and physical mapping of the mouse genome.

The ability to carry out high-resolution genetic mapping at high throughput in the mouse is a critical rate-limiting step in the generation of genetically anchored contigs in physical mapping projects and the mapping of genetic loci for complex traits. To address this need, we have developed an efficient, high-resolution, large-scale genome mapping system. This system is based on the identification of polymorphic DNA sites between mouse strains by using interspersed repetitive sequence (IRS) PCR. Individual cloned IRS PCR products are hybridized to a DNA array of IRS PCR products derived from the DNA of individual mice segregating DNA sequences from the two parent strains. Since gel electrophoresis is not required, large numbers of samples can be genotyped in parallel. By using this approach, we have mapped > 450 polymorphic probes with filters containing the DNA of up to 517 backcross mice, potentially allowing resolution of 0.14 centimorgan. This approach also carries the potential for a high degree of efficiency in the integration of physical and genetic maps, since pooled DNAs representing libraries of yeast artificial chromosomes or other physical representations of the mouse genome can be addressed by hybridization of filter representations of the IRS PCR products of such libraries.

Animals↗
PubMed1995

Assessment of skeletal muscle viability by PET.

UNLABELLED: We investigated the use of [18F]fluoro-2-deoxyglucose (FDG) PET scanning for assessment of skeletal muscle viability in patients with peripheral vascular disease and in patients following free-flap skeletal muscle transfer for closure of open wounds. METHODS: We obtained 32 FDG-PET scans from 30 patients, either at the time of admission for peripheral vascular disease (n = 16) or between 1 and 15 days after surgery for skeletal muscle transfer (n = 16). Ratios between injured and contralateral limb FDG tracer activity uptake were correlated with clinical outcome at 1 mo to 3 yr follow-up. RESULTS: Viable muscle uptake ratios ranged from 0.47 to 7.88 (mean: 2.26 +/- 1.81; n = 26), while nonviable muscle uptake ratios ranged from 0.12 to 0.46 (mean: 0.27 +/- 0.12; n = 6; p < 0.02). After skeletal muscle transfer, two patients with viable tissue, as documented by PET, required amputation due to osteomyelitis, and one patient with peripheral vascular disease who showed viable tissue by PET required amputation 3 mo after the PET scan because of recurrent ulcers. CONCLUSION: FDG-PET scanning can determine skeletal muscle viability in patients with peripheral vascular disease and in patients following free-flap transfer.

Adolescent↗
PubMed1994

IRE-bubble PCR: a rapid method for efficient and representative amplification of human genomic DNA sequences from complex sources.

A significant issue in the analysis of any genomic DNA segment is the generation of a unique set of short single-copy sequences that are representative of that region. In this report we describe a novel technique, IRE-bubble PCR, which was designed to amplify the human DNA content of somatic cell hybrids, YACs, cosmids, and lambda phage and result in greater complexity and representation than standard inter-IRE PCR. Here we demonstrate that IRE-bubble PCR is species specific and that it results in the generation of a product that is at least 10-fold more complex and representative than that produced by standard inter-IRE PCR. In addition, we have addressed the factors that contribute to the representation of the IRE-bubble PCR product and show how they may be used to further increase the complexity of this reaction. Finally, we have illustrated how the complexity and distribution of products generated by IRE-bubble PCR can be exploited and applied to FISH mapping and "chromosome painting" as well as to the generation of STSs targeted to specific chromosomal or subchromosomal regions.

Animals↗