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Biomedical subjects

C DeWitt

Publications and source records attributed to C DeWitt.

At least 19 recordsLinked to original sources
PubMed2000

Human extrapulmonary dirofilariasis in Texas.

Human pulmonary infection due to the dog heartworm, Dirofilaria immitis, has been reported in the medical literature for many decades. Extrapulmonary infection due to this pathogen is less widely reported, including only nine cases in North America. We report a case of extrapulmonary dirofilariasis manifested as asymptomatic nodular lesions in the anterior abdominal wall of a patient having exploratory laparotomy for carcinoma. We review previously reported cases and discuss the pathophysiology of both pulmonary and extrapulmonary dirofilariasis.

Abdominal Muscles↗
PubMed1998

DNA vaccines against tuberculosis.

DNA plasmids encoding Mycobacterium tuberculosis antigen 85 (Ag85) were tested as vaccines in animal models. Ag85 DNA induced relevant immune responses (i.e. T helper (Th) cells, Th1 cytokines and cytotoxic T lymphocytes) and was protective in mouse and guinea pig models of mycobacterial disease. Therefore, DNA vaccination holds promise as an effective means of preventing tuberculosis in humans. Furthermore, this technique is amenable to identifying the protective antigens of M. tuberculosis.

Acyltransferases↗
PubMed1998

Protective CD4+ and CD8+ T cells against influenza virus induced by vaccination with nucleoprotein DNA.

DNA vaccination is an effective means of eliciting both humoral and cellular immunity, including cytotoxic T lymphocytes (CTL). Using an influenza virus model, we previously demonstrated that injection of DNA encoding influenza virus nucleoprotein (NP) induced major histocompatibility complex class I-restricted CTL and cross-strain protection from lethal virus challenge in mice (J. B. Ulmer et al., Science 259:1745-1749, 1993). In the present study, we have characterized in more detail the cellular immune responses induced by NP DNA, which included robust lymphoproliferation and Th1-type cytokine secretion (high levels of gamma interferon and interleukin-2 [IL-2], with little IL-4 or IL-10) in response to antigen-specific restimulation of splenocytes in vitro. These responses were mediated by CD4+ T cells, as shown by in vitro depletion of T-cell subsets. Taken together, these results indicate that immunization with NP DNA primes both cytolytic CD8+ T cells and cytokine-secreting CD4+ T cells. Further, we demonstrate by adoptive transfer and in vivo depletion of T-cell subsets that both of these types of T cells act as effectors in protective immunity against influenza virus challenge conferred by NP DNA.

Animals↗
PubMed1997

Pulsed low dose rate brachytherapy in a rat model: dependence of late rectal injury on radiation pulse size.

PURPOSE: Clinical protocols utilizing pulsed low dose rate brachytherapy (PDR) to replace traditional continuous low dose rate brachytherapy (CLDR) employ irradiation in individual pulses given at intervals of a few hours. A critical factor in determining whether PDR will produce equivalent or greater late-occurring normal tissue toxicity is the dose per pulse. A rat rectal model was used to determine the role of pulse size in modifying dose effectiveness in producing late-occurring toxicity. METHODS AND MATERIALS: A rat model in which the rectum is irradiated with 192Ir sources was used in conjunction with an intracavitary applicator. A section of rectum 1.3 cm in length was irradiated with either 0.75 Gy/h CLDR or one of five schemes of PDR. The schemes applied 0.375, 0.75, 1.5, 3.0, or 6.0 Gy pulses at 0.5, 1.0, 2.0, 4.0, or 8.0 h intervals, respectively. Rats were observed for up to 300 days after completion of irradiation for rectal obstruction. Rectal specimens were taken at the time of sacrifice for obstruction or at the end of follow-up and analyzed histologically for injury. RESULTS: Effectiveness of irradiation was analyzed by calculating the ED50 for incidence of obstruction and severe histological injury. The ED50 for obstruction after treatment with CLDR and pulse sizes of 0.375, 0.75, and 1.5 Gy were 70.5, 68.0, 68.6, and 68.8 Gy, respectively. These values were not significantly different. Compared to CLDR, the ED50 for obstruction after pulse sizes of 3.0 and 6.0 Gy were significantly different at 60.9 and 46.3 Gy, respectively. The relative changes in ED50 for the different radiation schemes in producing ulceration, fibrosis, and vascular sclerosis injury were similar to that observed for obstruction. The endpoints of colitis cystica profunda and atypical epithelial regeneration varied less with increasing pulse size. CONCLUSIONS: We have demonstrated that for late rat rectal injury, dose responses to PDR pulse sizes up to 1.5 Gy at 2-h intervals are not distinguishable from that seen with CLDR at a dose rate of 0.75 Gy/h.

Animals↗
PubMed1992

Physiologic responses to recumbent versus upright cycle ergometry, and implications for exercise prescription in patients with coronary artery disease.

To clarify the influence of body position on exercise prescription, 14 men (mean age +/- standard deviation 60.0 +/- 6.1 years) with coronary artery disease who underwent randomized recumbent and upright cycle ergometer tests to volitional fatigue were studied. At 100 watts, heart rate (HR), systolic blood pressure, oxygen consumption (VO2), rate pressure product and rating of perceived exertion were greater (p less than 0.05) in the upright than in the recumbent position. At peak exercise, however, these variables were not significantly different. Regressions of relative HR versus VO2 for recumbent and upright cycle ergometry were comparable: y = 1.24x - 32.7 and y = 1.26x - 31.5, respectively, where y = % maximal VO2, and x = % maximal HR. These findings indicate that recumbent exercise prescriptions may be based on the peak HR and VO2 values obtained during upright cycle ergometry, and vice versa. However, differences in the cardiorespiratory responses at submaximal exercise preclude the interchangeability of upright and recumbent training work rates.

Aged↗
PubMed1983

Histocompatibility in couples with recurrent spontaneous abortion and normal fertility.

Histocompatibility between husband and wife at the HLA locus has been suggested as a determinant of recurrent spontaneous abortion. We measured the incidence of HLA antigen sharing within 12 couples with histories of unexplained recurrent abortion and in a fertile control population of 77 couples. In the recurrent abortion group, 6 of 12 (50%) of the couples shared no HLA antigens, whereas only 3 of 12 (25%) shared one antigen, 1 of 12 (8.3%) shared two antigens, and 2 of 12 (17%) shared three antigens. In the fertile group, 27 of 77 (35.1%) shared no antigens, 33 of 77 (42.8%) shared one antigen, 14 of 77 (18.2%) shared two antigens, 2 of 77 (2.6%) shared three antigens, and 1 of 77 (1.3%) shared four antigens. In 50 of these control couples who were available for complete reproductive histories, there were no significant correlations between the incidence of antigen sharing and the numbers of offspring, the incidence of spontaneous abortion, or infertility problems. Six of the women in the recurrent abortion group became pregnant during the study. Three of these (50%) delivered live infants independent of the degree of antigen sharing and without the benefit of immunologic treatment. Therefore, the degree of HLA antigen sharing did not define a population with increased pregnancy wastage or predict subsequent pregnancy outcome.

Abortion, Habitual↗
PubMed1983

9-([2-hydroxy-1-(hydroxymethyl)ethoxy]methyl)guanine: a selective inhibitor of herpes group virus replication.

9-([2-Hydroxy-1-(hydroxymethyl)ethoxy]methyl)guanine (2'-nor-2'-deoxyguanosine; 2'NDG) selectively inhibits the replication of herpes group viruses. In cell culture studies 2'NDG was at least 10-fold more potent than acyclovir (ACV) in inhibition of human cytomegalovirus replication and Epstein-Barr virus-induced lymphocyte transformation and was about as effective as ACV in inhibition of herpes simplex viruses 1 and 2 and varicella zoster virus. Orally administered 2'NDG was 6- to 50-fold more efficacious than ACV in treating systemic or local HSV-1 infection or HSV-2 intravaginal infection in mice. The mode of action of 2'NDG appears to involve phosphorylation by herpes simplex virus thymidine kinase and subsequent phosphorylations by cellular kinases to produce 2'NDG triphosphate, which is a potent inhibitor of herpes virus DNA polymerase. Compared to ACV, 2'NDG was a more efficient substrate for HSV-1 thymidine kinase (Vmax/Km for 2'NDG 30-fold higher than that of ACV), whereas 2'NDG monophosphate is a more efficient substrate for GMP kinase (Vmax/Km for 2'NDG monophosphate 492-fold higher than that for ACV monophosphate). The combined effect is more rapid production of the inhibitory triphosphate from 2'NDG than from ACV.

Acyclovir↗
PubMed1981

Uncle Sam wants you.

Explore the source record for details and available documents.

Emergency Medical Services↗
PubMed1981

Volunteers ease suffering in Thailand hospital.

As thousands of Cambodian refugees idly wait to be resettled in other countries or to return to Cambodia, volunteer medical personnel are providing them with the medical care and education that they so desperately need.

Cambodia↗