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Biomedical subjects

M L Tang

Publications and source records attributed to M L Tang.

26 records · Page 2Linked to original sources
PubMed1994

Reduced interferon-gamma secretion in neonates and subsequent atopy.

Low interferon-gamma (IFN-gamma) secretion has been found in individuals with active atopic disease. Whether this is a cause or result of the disease process is uncertain. Cord blood IFN-gamma secretion was examined in 35 neonates who were then prospectively followed up for 1 year for the development of atopic disease. Infants who developed either symptoms of atopic disease or a positive IgE-mediated skin prick test at 12 months of age produced significantly less IFN-gamma at birth compared with those who did not (p = 0.005). This reduced secretion of IFN-gamma at birth indicates that the defect in interferon secretion is a primary component of the atopic state rather than an effect of the disease process.

Breast Feeding↗
PubMed1994

Efficient power computation for exact and mid-P tests for the common odds ratio in several 2 x 2 tables.

When designing a study that may generate a set of sparse 2 x 2 tables, or when confronted with 'negative' results upon exact analysis of such tables, we need to compute the power of exact tests. In this paper we provide an efficient approach for computing exact unconditional power for four exact tests on the common odds ratio in a series of 2 x 2 tables. These tests are the traditional exact test; a test based on a probability ordering of the sample space; and two tests based on ordering the sample space according to distance from the mean, or median. For each test, we consider both a conservative version and a mid-P adjusted version. We explore three computational options for power determination: exact power computation, calculation of exact upper and lower bounds for power, and Monte Carlo confidence bounds for power. We present an interactive program implementing these options. For study design, the program may be run several times to arrive at a sample configuration with adequate power.

Case-Control Studies↗
PubMed1994

Reduced interferon-gamma (IFN-gamma) secretion with increased IFN-gamma mRNA expression in atopic dermatitis: evidence for a post-transcriptional defect.

Reduced secretion of IFN-gamma in atopic individuals has been implicated in the pathogenesis of disease, though the mechanisms leading to this reduced secretion have not been elucidated. As production of IFN-gamma has been shown to be predominantly regulated by its rate of transcription, expression of IFN-gamma mRNA was examined in atopic children and in age-matched, non-atopic controls by polymerase chain reaction (PCR)-assisted mRNA amplification. Children with atopic dermatitis were found to have constitutive expression of IFN-gamma mRNA in freshly isolated peripheral blood mononuclear cells (PBMC) and in unstimulated PBMC cultures which increased further following stimulation with phorbol myristate acetate (PMA)/Ca in vitro. In contrast, expression of IFN-gamma mRNA in controls was only detected in stimulated cultures, as has been demonstrated previously for normal adults. These findings demonstrate that circulating T cells from atopic children have been activated in vivo, and suggest that T cell activation is a significant component of the inflammatory process in atopic dermatitis. Although expression of IFN-gamma mRNA was increased in the atopic children, secretion was confirmed to be significantly lower than in controls, indicating that the defect(s) underlying reduced IFN-gamma secretion in these individuals lie post-transcriptionally.

Base Sequence↗
PubMed1994

Spontaneous expression of IL-4 mRNA in lymphocytes from children with atopic dermatitis.

Normal lymphocytes do not generally produce or secrete lymphokines in the resting or unstimulated state and only express or release cytokines following activation. Recently, the spontaneous production of intracellular interferon-gamma (IFN-gamma) and spontaneous secretion of IL-6 has been documented in patients with atopic dermatitis. These findings indicated that lymphocytes had been previously activated in vivo. Such in vivo activation may also be associated with spontaneous production of IL-4. As measurement of IL-4 secretion by immunoassay is complicated by poor sensitivity, and only provides information on the net amount of cytokine present after secretion, adsorption, consumption and degradation have occurred, IL-4 mRNA expression in peripheral blood lymphocytes from children with atopic dermatitis and controls was examined by polymerase chain reaction (PCR)-assisted mRNA amplification. Spontaneous expression of IL-4 mRNA was detected in four of eight patients with severe atopic dermatitis. Following stimulation in vitro, seven of eight atopic patients demonstrated detectable IL-4 mRNA. In comparison, no spontaneous expression of IL-4 mRNA was found in controls, and only six of 10 controls expressed IL-4 mRNA in stimulated cultures. The spontaneous expression of IL-4 mRNA in unstimulated cultures from children with atopic dermatitis supports the possibility that previous in vivo activation has occurred, and suggests that IL-4 production is increased in vivo in atopic dermatitis. This in vivo activation together with the constitutive expression of IL-4 mRNA are likely to contribute to the spontaneous in vitro production of IgE in atopic patients.

Base Sequence↗
PubMed1993

The sartorius myocutaneous island flap.

The vascular supply to the distal part of sartorius m. was studied in 37 limbs by dissection under magnification and after black ink and latex injections. The muscle or myocutaneous island flap pedicled on the saphenous artery (SA) is supplied by a retrograde circulation through anastomoses of the SA with the perforating branches of the posterior tibial artery and the medial inferior genicular artery. Three different vascular patterns were defined. Retrograde injection also showed good perfusion of the SA. The flap is useful for covering around the knee, the proximal and middle thirds of the lower leg, and the end of the amputation stump. Raising of the flap has not resulted in any functional or cosmetic defect. Eighteen operations have so far been performed, six using the muscle island flap and twelve using the myocutaneous island flap, and all survived completely.

Humans↗
PubMed1993

Growth hormone deficiency and combined immunodeficiency.

The first description of an association of isolated growth hormone deficiency (IGHD) and combined immunodeficiency is presented. The findings suggest that IGHD should be considered as a cause of short stature in children with combined immunodeficiency before attributing growth retardation to infection.

Child, Preschool↗