Biomedical subjects

M Kennedy

Publications and source records attributed to M Kennedy.

At least 37 records · Page 2Linked to original sources

PubMed2001

Regulation of hemangioblast development.

The in vitro differentiation of embryonic stem (ES) cells provides a powerful approach for studying the earliest events involved in the commitment of the hematopoietic and endothelial lineages. Using this model system, we have identified a precursor with the potential to generate both primitive and definitive hematopoietic cells as well as cells with endothelial characteristics. The developmental potential of this precursor suggests that it represents the in vitro equivalent of the hemangioblast, a common stem cell for both lineages. ES cells deficient for the transcription factor scl/tal-1 are unable to generate hemangioblasts, while those deficient for Runx1 generate reduced numbers of these precursors. These findings indicate that both genes play pivotal roles at the earliest stages of hematopoietic and endothelial development. In addition, they highlight the strength of this model system in studying the function of genes in embryonic development.

Animals↗

PubMed2001

Normal light response, photoreceptor integrity, and rhodopsin dephosphorylation in mice lacking both protein phosphatases with EF hands (PPEF-1 and PPEF-2).

Rhodopsin dephosphorylation in Drosophila is a calcium-dependent process that appears to be catalyzed by the protein product of the rdgC gene. Two vertebrate rdgC homologs, PPEF-1 and PPEF-2, have been identified. PPEF-1 transcripts are present at low levels in the retina, while PPEF-2 transcripts and PPEF-2 protein are abundant in photoreceptors. To determine if PPEF-2 alone or in combination with PPEF-1 plays a role in rhodopsin dephosphorylation and to determine if retinal degeneration accompanies mutation of PPEF-1 and/or PPEF-2, we have produced mice carrying targeted disruptions in the PPEF-1 and PPEF-2 genes. Loss of either or both PPEFs has little or no effect on rod function, as mice lacking both PPEF-1 and PPEF-2 show little or no changes in the electroretinogram and PPEF-2-/- mice show normal single-cell responses to light in suction pipette recordings. Light-dependent rhodopsin phosphorylation and dephosphorylation are also normal or nearly normal as determined by (i) immunostaining of PPEF-2-/- retinas with the phosphorhodopsin-specific antibody RT-97 and (ii) mass spectrometry of C-terminal rhodopsin peptides from mice lacking both PPEF-1 and PPEF-2. Finally, PPEF-2-/- retinas show normal histology at 1 year of age, and retinas from mice lacking both PPEF-1 and PPEF-2 show normal histology at 3 months of age, the latest time examined. These data indicate that, in contrast to loss of rdgC function in Drosophila, elimination of PPEF function does not cause retinal degeneration in vertebrates.

Alleles↗

PubMed2001

Resistance exercise training reduces hypertriglyceridemia in HIV-infected men treated with antiviral therapy.

Hypertriglyceridemia, peripheral insulin resistance, and trunk adiposity are metabolic complications recently recognized in people infected with human immunodeficiency virus (HIV) and treated with highly active antiretroviral therapy (HAART). These complications may respond favorably to exercise training. Using a paired design, we determined whether 16 wk of weight-lifting exercise increased muscle mass and strength and decreased fasting serum triglycerides and adipose tissue mass in 18 HIV-infected men. The resistance exercise regimen consisted of three upper and four lower body exercises done for 1-1.5 h/day, 4 days/wk for 64 sessions. Dual-energy X-ray absorptiometry indicated that exercise training increased whole body lean mass 1.4 kg (P = 0.005) but did not reduce adipose tissue mass (P = NS). Axial proton-magnetic resonance imaging indicated that thigh muscle cross-sectional area increased 5-7 cm(2) (P < 0.005). Muscle strength increased 23-38% (P < 0.0001) on all exercises. Fasting serum triglycerides were decreased at the end of training (281-204 mg/dl; P = 0.02). These findings imply that resistance exercise training-induced muscle hypertrophy may promote triglyceride clearance from the circulation of hypertriglyceridemic HIV-infected men treated with antiviral therapy.

Adipose Tissue↗

PubMed2001

Detection of feline coronavirus infection in captive cheetahs (Acinonyx jubatus) by polymerase chain reaction.

Feline coronavirus genetic elements were detected by polymerase chain reaction from blood, fecal samples, and effusive fluid collected from 33 cheetahs in the U.S.A. Feline coronavirus-specific serum antibodies were also measured by indirect immunofluorescence. Ten cheetahs were positive for viral shedding by polymerase chain reaction, whereas 13 were seropositive by immunofluorescence. Results of serology did not consistently correlate with shedding of virus, and the capture antigen used for detection of feline coronavirus-specific antibodies had a significant impact on results. Testing of samples from one population over a 1-yr period indicated chronic infection in some animals. These relatively healthy carrier animals were a source of virus for contact animals. Screening programs in cheetah populations for feline coronavirus infection may be most reliable if a combination of serologic analysis and viral detection by polymerase chain reaction is used.

Acinonyx↗

PubMed2001

Consumer acceptance of irradiated meat and poultry in the United States.

Food manufacturers in the United States are currently allowed to irradiate raw meat and poultry to control microbial pathogens and began marketing irradiated beef products in mid-2000. Consumers can reduce their risk of foodborne illness by substituting irradiated meat and poultry for nonirradiated products, particularly if they are more susceptible to foodborne illness. The objective of this study was to identify the individual characteristics associated with willingness to buy irradiated meat and poultry, with a focus on five risk factors for foodborne illness: unsafe food handling and consumption behavior, young and old age, and compromised immune status. A logistic regression model of willingness to buy irradiated meat or poultry was estimated using data from the 1998-1999 FoodNet Population Survey, a single-stage random-digit dialing telephone survey conducted in seven sites covering 11% of the U.S. population. Nearly one-half (49.8%) of the 10,780 adult respondents were willing to buy irradiated meat or poultry. After adjusting for other factors, consumer acceptance of these products was associated with male gender, greater education, higher household income, food irradiation knowledge, household exposure to raw meat and poultry, consumption of animal flesh, and geographic location. However, there was no difference in consumer acceptance by any of the foodborne illness risk factors. It is unclear why persons at increased risk of foodborne illness were not more willing to buy irradiated products, which could reduce the hazards they faced from handling or undercooking raw meat or poultry contaminated by microbial pathogens.

Age Factors↗

PubMed2001

Reparative changes and the false-positive/false-negative Papanicolaou test: a study from the College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology .

CONTEXT: Reparative changes can be a diagnostic challenge on Papanicolaou tests and must be distinguished from epithelial cell abnormalities. Both squamous intraepithelial lesions (SIL) and carcinoma may be underdiagnosed as repair. This study examines laboratory and cytologist performance in the diagnosis of repair. OBJECTIVES: To determine if laboratories and cytologists can consistently distinguish reparative changes from SIL and carcinoma and to document how often SIL and carcinoma are mistaken for repair in a standardized educational slide program. DESIGN: Results for reparative changes, SIL, and carcinoma slides from the College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology for 1998 were analyzed. Only results from validated referenced slide responses were used. RESULTS: The concordancy rate for reparative-change slides, that is, any response of within normal limits or benign cellular changes, ranged from 91% to 94% for cytotechnologist, pathologist, and laboratory responses. False-negative rates for squamous carcinoma and adenocarcinoma, high-grade SIL, and low-grade SIL ranged from 0.47% to 5.41%; the proportion of false-negative diagnoses of reparative changes ranged from 24% to 62% of all discordant responses. CONCLUSIONS: Of all benign cellular changes and within normal limits categories in the Interlaboratory Comparison Program in Cervicovaginal Cytology, repair most often elicits a false-positive laboratory response. Underdiagnosing epithelial abnormalities as repair is also a source of false-negative Papanicolaou test results.

Cervix Uteri↗

PubMed2001

Posterior fossa tumours in childhood: evaluation of presenting clinical features.

A retrospective review was performed of the age profile and clinical features at presentation of 79 children with posterior fossa tumours. The mean age at presentation in this series (6.6 years) is consistent with a decreasing trend over the past 70 years. Headaches, ataxia and torticollis emerge as significant symptoms worthy of further investigation whilst abdominal pain and constipation might herald the presence of a posterior fossa tumour on rare occasions.

Adolescent↗

PubMed2001