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Biomedical subjects

S Thomas

Publications and source records attributed to S Thomas.

At least 307 records · Page 17Linked to original sources

User fees, self-selection and the poor in Bangladesh.

The widespread uncontrolled introduction of user fees in any developing country is likely to have a disastrous impact on poorer patients. Furthermore, traditional targeting schemes aimed at their exemption are often expensive, difficult to administer and ineffective at reaching those in greatest need. This research study examines how user fees can raise revenue and target poorer patients, under the right market conditions, without resorting to costly targeting schemes. The authors draw their findings from case studies of cost recovery in the health and population sectors in Bangladesh. The mechanism suggested in the paper is to use self-selection. It is argued that under certain market conditions poorer patients will choose the health-care option that is appropriate to their means. They will thus identify themselves as poor without having to be selected or tested by an independent authority. This self-selection allows the relevant authorities to cross-subsidize their market choice by over-charging the non-poor in other segments of the market.

Bangladesh↗

The mouse Mid1 gene: implications for the pathogenesis of Opitz syndrome and the evolution of the mammalian pseudoautosomal region.

We have recently reported isolation of the gene responsible for X-linked Opitz G/BBB syndrome, a defect of midline development. MID1 is located on the distal short arm of the human X chromosome (Xp22. 3) and encodes a novel member of the B box family of zinc finger proteins. We have now cloned the murine homolog of MID1 and performed preliminary expression studies during development. Mid1 expression in undifferentiated cells in the central nervous, gastrointestinal and urogenital systems suggests that abnormal cell proliferation may underlie the defect in midline development characteristic of Opitz syndrome. We have also found that Mid1 is located within the mouse pseudoautosomal region (PAR) in Mus musculus , while it seems to be X-specific in Mus spretus. Therefore, Mid1 is likely to be a recent acquisition of the M. musculus PAR. Genetic and FISH analyses also demonstrated a high frequency of unequal crossovers in the murine PAR, creating spontaneous deletion/duplication events involving Mid1. These data provide evidence for the first time that genetic instability of the PAR may affect functionally important genes. In addition, we show that MID1 is the first example of a gene subject to X-inactivation in man while escaping it in mouse. These data contribute to a better understanding of the molecular content and evolution of the rodent PAR.

Abnormalities, Multiple↗

Autotransplantation of teeth: is there a role?

Autotransplantation of teeth, if carried out successfully, ensures that alveolar bone volume is maintained due to physiological stimulation of the periodontal ligament. Autotransplantation has been carried out for many years, but with varying success rates. As a result, it is seldom regarded as an appropriate treatment option for patients with missing teeth especially with the continued development of osseo-integrated implants. Since placement of osseo-integrated implants in growing alveolar bone is contra-indicated, transplantation of available teeth remains a suitable choice for replacing missing units in the young patient. The role of autotransplantation of teeth in several clinical situations, the clinical techniques involved and factors influencing success of the transplant are discussed. The aim of this paper is to underline the evidence based principles for successful autotransplantation and present the technique as a viable treatment option in present day orthodontic practice.

Anodontia↗

Induced resistance responses in maize.

Systemic acquired resistance (SAR) is a widely distributed plant defense system that confers broad-spectrum disease resistance and is accompanied by coordinate expression of the so-called SAR genes. This type of resistance and SAR gene expression can be mimicked with chemical inducers of resistance. Here, we report that chemical inducers of resistance are active in maize. Chemical induction increases resistance to downy mildew and activates expression of the maize PR-1 and PR-5 genes. These genes are also coordinately activated by pathogen infection and function as indicators of the defense reaction. Specifically, after pathogen infection, the PR-1 and PR-5 genes are induced more rapidly and more strongly in an incompatible than in a compatible interaction. In addition, we show that monocot lesion mimic plants also express these defense-related genes and that they have increased levels of salicylic acid after lesions develop, similar to pathogeninfected maize plants. The existence of chemically inducible disease resistance and PR-1 and PR-5 gene expression in maize indicates that maize is similar to dicots in many aspects of induced resistance. This reinforces the notion of an ancient plant-inducible defense pathway against pathogen attack that is shared between monocots and dicots.

Amino Acid Sequence↗

The TAATGARAT motif in the herpes simplex virus immediate-early gene promoters can confer both positive and negative responses to cellular octamer-binding proteins when it is located within the viral genome.

The TAATGARAT motif in the herpes simplex virus (HSV) immediate-early (IE) gene promoters plays a key role in their activation by the Oct-1-Vmw65 complex, but its role in mediating inhibitory effects of cellular octamer-binding proteins is less clear. We have used indicator viruses containing reporter constructs with different IE promoters driving a reporter beta-galactosidase gene within the viral genome to investigate this. We showed that deletion of the upstream IE promoter region containing the TAATGARAT motifs abolishes the inhibitory effect of the cellular octamer-binding proteins Oct-2.4 and Oct-2.5 on the viral IE promoter. This inhibitory effect can be restored by addition of a single TAATGARAT motif to the minimal promoter within the viral genome. Hence, the TAATGARAT motif can indeed mediate both positive and negative effects of cellular transcription factors when it is located within the viral genome.

Animals↗

Sample dilution to resolve mistaken identification of haemoglobin D as haemoglobin E using the variant automated system.

High performance liquid chromatography (HPLC) is increasingly being used to estimate variant haemoglobins. A case of haemoglobin S/D (HbS/D) is presented, which was misdiagnosed as haemoglobin S/E (HbS/E) by HPLC. The patient was a 22 year old woman with sickle cell anaemia. Subsequent haemodilution by blood transfusion clearly elucidated the haemoglobin D peak on HPLC. Sample dilution experiments, using the pretransfusion sample, were done resulting in correct elution of the peak in the D window. Troubleshooting in similar problematic haemoglobin variant peaks seen on HPLC can be done by sample dilution.

Adult↗

Atopy phenotype.

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Genetic Variation↗

Airway response of children with primary ciliary dyskinesia to exercise and beta2-agonist challenge.

In primary ciliary dyskinesia (PCD), chest physiotherapy for airway clearance is essential. Exercise and inhaled beta2-agonists can produce bronchodilation thereby augmenting physiotherapy. However, both can also cause bronchoconstriction, and the effects of these stimuli in PCD are not known. In a preliminary study, the mean coefficients of variation for forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and peak expiratory flow rate (PEFR) in children with PCD were determined. They were 5.4%, 4.4% and 8.4%, respectively. Twelve children with PCD and 12 normal children performed pulmonary functions under resting conditions; during and after a validated treadmill exercise test; and before and 15 min after 200 microg of inhaled salbutamol. At baseline, FEV1, FVC, forced mid-expiratory flow (FEF25-75%) and PEFR were significantly reduced in the PCD group compared with the control group. Exercise produced a significant increase in PEFR in the PCD group. There was no significant difference between the groups in response to salbutamol. Within the PCD group, exercise produced a significantly greater increase in PEFR than beta2-agonist therapy. In conclusion, in children with primary ciliary dyskinesia there is evidence of obstructive pulmonary disease. In these children, exercise is a more potent stimulus for bronchodilation than by inhaled beta2-agonists. Enhancement of airway clearance may best be achieved by encouraging patients to exercise before physiotherapy rather than by inhaling beta2-agonists, but the effects of each should be assessed for each individual before instigating treatment.

Administration, Inhalation↗

Defense mechanisms development in children, adolescents, and late adolescents.

To replicate and extend Cramer's (1987) original cross-sectional study concerning the development of defense mechanisms, the Thematic Apperception Test responses of 148 students in Grades 2, 5, 8, 11, and college freshmen were collected and scored for denial, projection, and identification using Cramer's Defense Mechanisms Manual (1991). Our results supported the notion that the relative use of denial and projection decreases and identification increases as a function of grade level. The findings provide additional support for the psychoanalytic view (Freud, 1966) of an ontogenetic developmental line of defense.

Adolescent↗

Odour-absorbing dressings.

This study uses an objective test system that compares the ability of different dressings to prevent the passage of a volatile amine when applied to a wound model under simulated 'in-use' conditions. Five dressings containing activated charcoal were tested by this method, and a low-adherent absorbent dressing was used as a control. Results demonstrate clear differences in the ability of the products to contain the test solution and prevent the loss of the volatile diethylamine into the surrounding air. Products which combine a physical absorbent with a charcoal component show enhanced performance.

Administration, Cutaneous↗

Autonomic regulation of the circulation during exercise and heat exposure. Inferences from heart rate variability.

Minimal information is available on the autonomic response to exercise under adverse environmental conditions. Traditionally, pharmacological blockade has been used to study autonomic responsiveness but, owing to its invasive nature, such studies have been limited in their scope. Recent advances in electrocardiographic tape recording, telemetry and associated computing systems have provided investigators with noninvasive methods for assessing the autonomic response to various physiological stressors. This article describes methods for the analysis of heart rate variability (HRV) and discusses the reports of those who have used HRV analysis to evaluate autonomic regulation during exercise, heat exposure and the combination of these 2 stressors. Spectral analysis of HRV reduces variations in the R-R interval into component sine waves of differing amplitude and frequency. Amplitude (variance) is displayed as a function of frequency, and power (cumulative variance) is calculated for specified frequency ranges (< 0.03 Hz, 0.03 to 0.15 Hz and 0.15 to 0.5 Hz). Parasympathetic nervous system activity can be inferred from the several indices of high frequency power; however, the estimation of sympathetic nervous system activity from low frequency power is more problematic. Data on HRV have shown that sympathovagal regulation during exercise is dependent on the intensity of the activity and the environmental conditions. At the onset of exercise, heart rate is increased by a reduction in vagal tone and a temporary increase in sympathetic tone. A continuation of physical activity is associated with a continued withdrawal of vagal activity and an attenuation of sympathetic nervous system tone. However, with the additional stimulus of a heated environment, sympathetic activity remains increased throughout exercise.

Adult↗

Major depression.

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Adolescent↗