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Biomedical subjects

V Ramesh

Publications and source records attributed to V Ramesh.

At least 19 recordsLinked to original sources
PubMed2006

Phenotypic spectrum associated with mutations of the mitochondrial polymerase gamma gene.

Mutations in the gene coding for the catalytic subunit of the mitochondrial DNA (mtDNA) polymerase gamma (POLG1) have recently been described in patients with diverse clinical presentations, revealing a complex relationship between genotype and phenotype in patients and their families. POLG1 was sequenced in patients from different European diagnostic and research centres to define the phenotypic spectrum and advance understanding of the recurrence risks. Mutations were identified in 38 cases, with the majority being sporadic compound heterozygotes. Eighty-nine DNA sequence changes were identified, including 2 predicted to alter a splice site, 1 predicted to cause a premature stop codon and 13 predicted to cause novel amino acid substitutions. The majority of children had a mutation in the linker region, often 1399G-->A (A467T), and a mutation affecting the polymerase domain. Others had mutations throughout the gene, and 11 had 3 or more substitutions. The clinical presentation ranged from the neonatal period to late adult life, with an overlapping phenotypic spectrum from severe encephalopathy and liver failure to late-onset external ophthalmoplegia, ataxia, myopathy and isolated muscle pain or epilepsy. There was a strong gender bias in children, with evidence of an environmental interaction with sodium valproate. POLG1 mutations cause an overlapping clinical spectrum of disease with both dominant and recessive modes of inheritance. 1399G-->A (A467T) is common in children, but complete POLG1 sequencing is required to identify multiple mutations that can have complex implications for genetic counselling.

Adolescent↗
PubMed2006

Alexander disease: ventricular garlands and abnormalities of the medulla and spinal cord.

BACKGROUND: Alexander disease is most commonly associated with macrocephaly and, on MRI, a leukoencephalopathy with frontal preponderance. The disease is caused by mutation of the GFAP gene. Clinical and MRI phenotypic variation have been increasingly recognized. METHODS: The authors studied seven patients with Alexander disease, diagnosed based on mutations in the GFAP gene, who presented unusual MRI findings. The authors reviewed clinical history, MRI abnormalities, and GFAP mutations. RESULTS: All patients had juvenile disease onset with signs of brainstem or spinal cord dysfunction. None of the patients had a macrocephaly. The MRI abnormalities were dominated by medulla and spinal cord abnormalities, either signal abnormalities or atrophy. One patient had only minor cerebral white matter abnormalities. A peculiar finding was the presence of a kind of garland along the ventricular wall in four patients. Three patients had an unusual GFAP mutation, one of which was a duplication mutation of two amino acids, and one an insertion deletion. CONCLUSION: Signal abnormalities or atrophy of the medulla or spinal cord on MRI are sufficient to warrant DNA analysis for Alexander disease. Ventricular garlands constitute a new sign of the disease. Unusual phenotypes of Alexander disease are found among patients with late onset and protracted disease course.

Adolescent↗
PubMed2006

Simple pulse-acquire NMR methods for the quantitative analysis of calcium, magnesium and sodium in human serum.

Simple pulse-acquire NMR methods are presented for accurate quantitation of calcium (Ca(2+)), magnesium (Mg(2+)) and sodium (Na(+)) in human serum. Ca(2+) and Mg(2+) can be determined simultaneously by (1)H NMR via their EDTA (ethylenediaminetetraacetic acid) complexes. Spectra are acquired before and after addition of EDTA, and the difference spectrum is used for integration of the signals from the complexes relative to an internal reference. Serum sodium can also be determined through pulse-acquire (23)Na NMR by integration of the free sodium signal relative to a reference signal (Na(+)+EDTA in a coaxial capillary tube). The method shows excellent accuracy and precision for all three metal ions. Slow chemical exchange between complexed and free EDTA at the natural pH of serum does not limit the accuracy of the determination of Ca(2+) and Mg(2+), and the large errors associated with spin-echo spectral editing methods are avoided.

Calcium↗
PubMed2006

Optimized 1D double quantum filter NMR experiments.

We propose and demonstrate a 1D pulse sequence to convert double quantum coherence (DQC) of y phase with optimal efficiency, relying on single transition selection. Our sequence has a larger high-sensitivity bandwidth with respect to the coupling, compared to other reconversion strategies. A modified version of the new pulse sequence provides the missing chemical shift and coupling information, at minor cost in sensitivity. Application to 1D 13C INADEQUATE is demonstrated. Our new sequence is also applied to quadrupole coupled spin-1 systems, such as 2H in lyotropic phase. Performance of the sequence may be fine-tuned by pulse flip angle optimization, taking into account relaxation effects.

Journal Article↗
PubMed2006

Evaluation of three different strengths of trichloroacetic acid in xanthelasma palpebrarum.

BACKGROUND: Xanthelasma is a common cutaneous condition that presents in the periocular region. Essentially benign, treatment is of cosmetic importance. OBJECTIVE: Evaluation of varying strengths of trichloroacetic acid (TCA) in xanthelasma palpebrarum. METHODS: Three strengths of TCA were used on 51 patients randomly after categorizing their xanthelasma into papulo-nodular, flat plaques and macular lesions. The average number of sittings was calculated in each category and patients were reviewed fortnightly. RESULTS: Papulo-nodular lesions required an average of two applications with 100%, 2.67 with 70% and 4.16 with 50% TCA. Flat plaques responded to an average of 1.43, 1.50 and 3.55 sittings with 100%, 70% and 50% TCA, respectively. Macular lesions responded to only one application of all strengths of TCA applied. Eleven patients developed hypopigmentation, five had hyperpigmentation and one developed mild scarring. CONCLUSION: 100% TCA gives the best results in papulo-nodular lesions, 100% or 70% TCA give similar results in flat plaque xanthelasma and in macular lesions 50% is sufficient. Hypopigmentation is the commonest side effect, followed by hyperpigmentation. Scarring is a minor problem.

Adult↗
PubMed2006

Blood transfusion and dermatology.

Blood transfusion is an accepted therapeutic procedure in all specialties of medicine. In dermatology, specialized techniques like plasmapheresis and extracorporeal photochemotherapy have provided a good treatment option in immune-mediated disorders like bullous dermatoses, collagen vascular diseases and cutaneous lymphomas. Other anecdotal and less substantiated reports point to its use in chronic disorders like atopic dermatitis and psoriasis. Untoward dermatological manifestations include mainly purpuric rash and GVHD. Since planned studies may not be possible, pertinent observations from chance situations on the effect of blood transfusion in dermatoses would add valuable information.

Blood Transfusion↗
PubMed2005

Robust pulmonary nodule segmentation in CT: improving performance for juxtapleural cases.

Two novel methods are proposed for robust segmentation of pulmonary nodules in CT images. The proposed solutions locate and segment a nodule in a semi-automatic fashion with a marker indicating the target. The solutions are motivated for handling the difficulty to segment juxtapleural, or wall-attached, nodules by using only local information without a global lung segmentation. They are realized as extensions of the recently proposed robust Gaussian fitting approach. Algorithms based on i) 3D morphological opening with anisotropic structuring element and ii) extended mean shift with a Gaussian repelling prior are presented. They are empirically compared against the robust Gaussian fitting solution by using a large clinical high-resolution CT dataset. The results show 8% increase, resulting in 95% correct segmentation rate for the dataset.

Algorithms↗
PubMed2005

How soon does cutaneous tuberculosis respond to treatment? Implications for a therapeutic test of diagnosis.

BACKGROUND: It is difficult to demonstrate Mycobacterium tuberculosis in smears or biopsies and to grow it in culture in cutaneous tuberculosis because most cases are paucibacillary. A therapeutic trial of antitubercular drugs is frequently used to confirm the diagnosis in difficult cases. Information is lacking on the response to antitubercular therapy in cutaneous tuberculosis; consequently there are no clear guidelines on when to expect a response and also when to abandon a therapeutic trial. METHODS: We studied the records of 60 patients treated for cutaneous tuberculosis at our hospital to study the time course of the therapeutic response. All patients were treated with a short-course antitubercular regimen consisting of isoniazid 300 mg daily, rifampicin 450 mg daily, ethambutol 800 mg daily and pyrazinamide 1500 mg daily for 2 months followed by isoniazid and rifampicin in the same doses for 4 months. At follow-up visits, each patient was assessed by a dermatologist who recorded the presence or absence of clinical improvement in the skin lesions. RESULTS: Of the 60 patients seen, eight patients did not follow up after the initial consultation, 48 patients improved with treatment and four patients were classified as treatment failures. The timing of the first visit varied from 3 days to 15 months (median 27.5 days, mean 58.96 +/- 94.50) after initiation of treatment. Twenty-one patients were recorded to have improved within the first month of therapy. Twenty-seven patients who first reported more than 30 days after initiation of treatment were found to have improved. Four patients failed to respond during follow up ranging from 3 to 17 months. CONCLUSION: When a therapeutic trial is undertaken in cutaneous tuberculosis, 6 weeks of therapy with four drugs appears adequate to prove (or disprove) the diagnosis.

Adolescent↗
PubMed2005

TNFR2 gene polymorphism in coronary artery disease.

BACKGROUND: Recently atherosclerosis and coronary artery disease (CAD) are considered to be inflammatory diseases. The genetic polymorphism in inflammatory markers has been well studied and found to be associated with development of CAD. AIM: To study the association of biallelic polymorphism at position 196 in exon 6 of tumor necrosis factor 2 (TNFR2) gene and coronary artery disease. SETTINGS AND DESIGN: The study design was a prospective case control study conducted at a tertiary referral center mainly catering to the north Indian population. MATERIALS AND METHODS: One hundred and fifty angiographically proven patients with coronary artery disease and one hundred and fifty age matched controls were genotyped for TNFR2 gene by polymerase chain reaction followed by analysis of restriction fragment length polymorphism. STATISTICAL ANALYSIS: Genotype frequencies were compared in patients and controls by Chi-square test. Binary logistic regression analysis was used to examine the relationship between genotypes and disease, incorporating other variables into the model. RESULTS: The incidence of CAD in those with MM genotype was 65% and in those with RM genotype was 42%. Genotype frequency shows significant association of MM genotype with development of CAD (P < 0.001; odds ratio-2.585; 95% confidence interval 1.533-4.359). The association of TNFR2 genotype with CAD persisted on logistic regression analysis. CONCLUSION: MM genotype of TNFR2 gene is associated with development of CAD and RM genotype appears to be protective.

Adolescent↗