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Biomedical subjects

D Allen

Publications and source records attributed to D Allen.

At least 109 records · Page 6Linked to original sources
PubMed1997

Endovascular stent implantation for severe recoarctation of the aorta: case report with angiographic and 18-month clinical follow-up.

A 45-year-old white male, 35-year status postrepair of coarctation of the aorta, presented with symptomatic recoarctation of the aorta. He was treated successfully by implantation of a single Palmaz stent. The pressure gradient was abolished with complete resolution of symptoms. Seven months poststent implant, angiography revealed good lumen diameter and a small pressure gradient. Over an 18-mo follow-up period, there has been no recurrence of symptoms. Primary stenting may have a significant role in the treatment of patients with symptomatic recoarctation of the aorta.

Angiography↗
PubMed1997

Expression of pro-inflammatory cytokines by TCR alpha beta+ and TCR gamma delta+ T cells in an experimental model of colitis.

An inflammatory bowel disease (IBD) comparable to human ulcerative colitis is induced upon transfer of T cell-depleted wild-type (F1) bone marrow into syngeneic T cell-deficient (tg epsilon26) mice (F1 --> tg epsilon26). Previously we have shown that activated CD4+ T cells predominate in transplanted tg epsilon26 mice, and adoptive transfer experiments verified the potential of these cells to cause disease in immunodeficient recipient mice. Using flow cytometry for the detection of intracellular cytokine expression, we demonstrate in the present study that large numbers of CD4+ and CD8+ TCR alphabeta+ T cells from the intraepithelial region and lamina propria of the colon of diseased, but not from disease-free mice, produced interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha). Large numbers of T cells from peripheral lymphoid tissues of these animals also expressed IFN-gamma and TNF-alpha, but few expressed interleukin-4, demonstrating a strong bias towards Th1-type T cell responses in these animals. TCR gammadelta+ T cells, typically minor constituents of the inflammatory infiltrate of the colon in F1 --> tg epsilon26 mice, also expressed IFN-gamma at a high frequency upon CD3 stimulation. In light of these findings we examined the potential involvement of TCR gammadelta+ T cells by testing their ability to induce colitis in tg epsilon26 mice. We report here that tg epsilon26 mice transplanted with T cell-depleted bone marrow from TCR alpha(null) and TCR beta(null) animals developed IBD. Furthermore, disease in these mice correlated with the development of peripheral and colonic TCR gammadelta+ T cells capable of IFN-gamma production. These results suggest that IFN-gamma may be a common mediator of IBD utilized by pathogenic T cells of distinct phenotype.

Animals↗
PubMed1997

Development of temporal contrast sensitivity in human infants.

The time course for the development of the temporal contrast sensitivity function in humans is uncertain. Some studies indicate that temporal contrast sensitivity is immature in infants. However, earlier work suggests that critical flicker fusion is adult-like by 2 months. We traced the development of temporal contrast sensitivity to uniform field flicker in 2-, 3- and 4-month-old infants using a modified preferential-looking technique that employed a rating scale. Two-month-old infants exhibited highest sensitivities at 1 and 2 Hz. Three- and 4-month infants exhibited peak sensitivity at 4 and 8 Hz, respectively. Overall temporal contrast sensitivity increased with age and the peak frequency shifted toward higher temporal frequencies. Using this paradigm, no infant subjects showed responses to 32 Hz, the highest temporal frequencies tested.

Age Factors↗
PubMed1997

Enzyme immunoassays using bispecific diabodies.

BACKGROUND: Bispecific antibodies with a first binding specificity to a target antigen and a second to an enzyme have great potential in enzyme immunoassays. As bispecific antibodies are difficult to make, the use of recombinant bispecific antibody fragments may provide a breakthrough. OBJECTIVES: To make bispecific antibody fragments directed against an enzyme and to demonstrate their application in enzyme immunoassays. STUDY DESIGN: Bispecific antibody fragments were assembled as diabodies (Holliger P., Prospero T., Winter G. Proc. Natl. Acad. Sci. USA 90, 1993, 6444-6448) directed to an enzyme, E. coli beta-galactosidase, and to each of three target antigens, hen-egg lysozyme (HEL), carcinoembryonic antigen (CEA), and HIV gpl20 (HIV). The diabodies were then evaluated in immunoassays. RESULTS: The HEL diabody was shown to recruit beta-galactosidase in a microtiter plate immunoassay in which diabody and enzyme were co-incubated with antigen, washed and enzyme substrate added. The CEA diabody was shown to detect CEA by immunocytochemical staining of transfected, CEA-expressing HeLa cells and of adenocarcinoma colon tissue sections, and the HIV diabody to detect gpl20 in immunoblots of total cell extracts. CONCLUSION: The results illustrate the diagnostic potential of diabodies in enzyme immunoassays.

Amino Acid Sequence↗
PubMed1997

Delay versus deviance in autistic social behavior.

The pattern of acquisition of social, communication, and daily living skills was examined for autistic children, compared to retarded and normal controls, by quantifying intradomain scatter on the Vineland Adaptive Behavior Scales. Autistic children were matched to normal children and mentally retarded children on Vineland raw scores; group differences in scatter were examined for each domain of adaptive behavior. Autistic children had significantly more scatter on Communication and Socialization than both control groups. Item analyses showed that the autistic children had particular weaknesses on items reflecting attention to and pragmatic use of language, as well as play and reciprocal social interaction; the autistic children had particular strengths on items reflecting written language and rote language skills, and rule-governed social behavior. The number of items showing consistent group differences, however, was small, suggesting that although autistic development appears sequentially deviant and not merely delayed, individual autistic children derive their scatter from different items, and are a developmentally heterogeneous group.

Activities of Daily Living↗
PubMed1997

Interlaboratory variation in the detection of clinically significant alloantibodies against human platelet alloantigens.

This report describes the results of eight workshop exercises which were designed to test the proficiency of laboratories in the detection of antibodies to human platelet antigens (HPA). Detection of the most clinically significant alloantibody, anti-HPA-1a, is adequate. However, despite improvements in consistency of test results between laboratories over the last 3 years, there is still a high probability that clinically significant antibodies against other HPA alloantigens will not be detected.

Antigens, Human Platelet↗
PubMed1997

Use of a multifenestrated indwelling lavage system for treatment of septic digital tenosynovitis in cattle.

Septic tenosynovitis was diagnosed in seven cattle on the basis of history, physical examination, radiographs, cytological examination of tendon sheath fluids, and microbial culture. A commercially available indwelling multifenestrated silicone rubber drain was used to perform frequent lavage of the flexor tendon sheaths. The sepsis resolved in all cattle. Five of six cattle for which long-term (> 1 year) follow-up information was available were clinically sound on the affected limb and had remained productive members of the herd.

Animals↗
PubMed1997

Nursing, knowledge and practice.

Recent commentators have suggested that academic knowledge is irrelevant to nursing practice and may actually undermine nursing's traditional caring ethos. Furthermore, by making nursing more academic, it is claimed that 'natural' but non-academic carers are prevented from pursuing a career in nursing. Debates about the relationship between nursing, knowledge and practice have a long history and have to be understood in terms of wider political and economic issues relating to nursing, its status within society and the changing role of nurses within the health services division of labour. One crucial issue is nursing's status as women's work. Critics of developments in nurse education draw an ideological equation between nursing work and the traditional female role. From this perspective the qualities that make a good nurse cannot be taught, rather they are founded on 'natural' feminine skills. Irrespective of whether caring is 'natural' or not, it is questionable as to whether, for today's nurses, being caring is sufficient. The shape of nursing jurisdiction is a long way removed from its origins in the Victorian middle-class household. In addition to their traditional caring role, contemporary nurses may also have complex clinical, management and research responsibilities, as well as being crucial coordinators of service provision. It is suggested that these and future developments in health services make the need for an educated nursing workforce even more pressing. In order to adequately prepare nurses for practice, however, it is vital that nurse education reflects the reality of service provision.

Career Mobility↗
PubMed1997

Comparison of oral bambuterol and terbutaline in elderly patients with chronic reversible airflow obstruction.

Bambuterol, a carbamate prodrug of terbutaline, is the first once-daily oral beta 2-agonist. The effect/side effect ratio of bambuterol oral solution was compared with terbutaline mixture in elderly patients with chronic reversible obstructive airways disease. The study was of a double-blind, crossover, randomized design and consisted of a 4-7-day run-in period followed by four consecutive treatment periods each of 2 weeks. The treatments were bambuterol solution 20 mg nocte (B20), 10 mg nocte (B10), terbutaline mixture 3 mg t.i.d., (T), and placebo solution (P). Patients measured daily peak expiratory flow rate (PEFR), asthma symptoms, use of inhaled beta 2-agonist, and tremor. Of 84 patients, 66 completed all periods. Mean age was 67 years (60-90), basal FEV1 1.49 L, and reversibility of FEV1 30%. Ninety-four percent of the patients used inhaled/oral steroids in constant dosage. All treatments were significantly more effective than placebo. B20 resulted in higher morning PEFR than T (306 +/- 2.9 L/min vs. 297 +/- 2.9 L/min), while B10 gave equivalent results to T. No differences were seen in the use of inhaled beta 2-agonist. Less shortness of breath was experienced during the night with B20 and during the day with B10 compared with placebo. Both B20 and T produced more tremor than B10 and P. In elderly patients with chronic reversible airways obstruction once-daily bambuterol (10-20 mg) has a better effect/side effect ratio than 3 mg terbutaline thrice daily.

Administration, Oral↗
PubMed1997

CD3-epsilon overexpressed in prothymocytes acts as an oncogene.

BACKGROUND: Upon engagement of the T cell receptor for antigen, its associated CD3 proteins recruit signal transduction molecules, which in turn regulate T lymphocyte proliferation, apoptosis, and thymocyte development. Because some signal transducing molecules recruited by CD3-epsilon, i.e., p56lck and p59fyn, are oncogenic and since we previously found that overexpression of CD3-epsilon transgenes causes a block in T lymphocyte and NK cell development, we tested the hypothesis that aberrant CD3-epsilon signaling leads both to abnormal T lymphocyte death and lymphomagenesis. MATERIALS AND METHODS: Ten independently derived transgenic mouse lines were generated with four different genomic CD3-epsilon constructs. Mice either homozygous or hemizygous for each transgene were analyzed for an arrest in T lymphocyte development and for the occurrence of T cell lymphomas. RESULTS: Aggressive clonal T cell lymphomas developed at very high frequencies in seven mouse lines with intermediate levels of copies of CD3-epsilon derived transgenes. However, these lymphomas were not found when high copy numbers of CD3-epsilon transgenes caused a complete block in early thymic development or when a transgene was used in which the exons coding for the CD3-epsilon protein were deleted. Analyses of a series of double mutant mice, tgCD3-epsilon x RAG-2null, indicated that lymphomagenesis was initiated in lineage-committed prothymocytes, i.e., before rearrangement of the T cell receptor genes. In addition, the transgene coding for the CD3-epsilon cytoplasmic domain and its transmembrane region induced a T cell differentiation signal in premalignant tgCD3-epsilon x RAG-2null mice. CONCLUSION: The nonenzymatic CD3-epsilon protein acted as a potent oncogene when overexpressed early in T lymphocyte development. Lymphomagenesis was dependent on signal transduction events initiated by the cytoplasmic domain of CD3-epsilon.

Animals↗
PubMed1996

Telling friends.

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Adaptation, Psychological↗
PubMed1996

Surgical treatment of subchondral cyst-like lesions in the tibia of an adult pony.

A 13 year-old pony was evaluated because of right hind limb lameness of acute onset. Radiographs of the right tarsus obtained shortly after the onset of lameness were normal, but results of nuclear scintigraphy were abnormal. Two radiolucent subchondral cyst-like lesions of the distal part of the tibia were seen on radiographs obtained 9 months later. The lesions were surgically decompressed, and the pony was sound 1 year later. It is hypothesized that a traumatic insult created a crack or split in the articular cartilage that allowed subsequent development of the cyst-like lesions.

Animals↗
PubMed1996

Laparoscopy during pregnancy.

OBJECTIVE: To compare the safety and efficacy of laparoscopic surgery with that of open laparotomy in pregnant patients. DESIGN: Six-year case-control study. SETTING: Tertiary care, university and community hospitals. PATIENTS: Population-based sample. From 1990 through 1995, 16 pregnant patients underwent laparoscopic surgery (study group) and 18 underwent open laparotomy (control group) during the first or second trimester. Follow-up ranged from 1 month to 6 years. INTERVENTION: In the study group, 4 patients underwent appendectomies and 12 underwent cholecystectomies. The control group included 7 appendectomies and 11 cholecystectomies. MAIN OUTCOME MEASURES: The 2 groups were compared for age, trimester, surgical time, oxygen saturation, end-tidal carbon dioxide, return of gastrointestinal tract function, duration of intravenous or intramuscular narcotics, postoperative stay, gestational age of delivery, 1- and 5-minute Apgar scores, birth weights, and complications. RESULTS: Age, trimester, oxygenation, end-tidal CO2, gestational age at delivery, Apgar scores, and birth weights were not different between the 2 groups. The patients who underwent laparoscopy had significantly longer operative times 82 vs 49 minutes), shorter stay (1.5 vs 2.8 days), earlier resumption of regular diet (1.0 vs 2.4 days), and shorter duration of intravenous or intramuscular narcotics (1.2 vs 2.6 days) (all P < .01). Four complications were found in the laparotomy group vs 6 in the laparoscopy group. CONCLUSIONS: Laparoscopic surgery in pregnant women significantly decrease hospitalization, decreases narcotic use, and quickens return to a regular diet when compared with open laparotomy in pregnant women. No significant differences between the 2 groups in perioperative morbidity or mortality were present. These data suggest that therapeutic laparoscopy during pregnancy in the first or second trimester is safe.

Adolescent↗