Biomedical subjects
S Prasad
Publications and source records attributed to S Prasad.
Clinical recording of risk factors in patients with myocardial infarction: relationship between psychiatric history and other risk factors.
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Telemedicine in ophthalmology.
Comprehensive telemedicine promises a world of medicine freed of geographic borders, time zones, and personnel shortages. It could open the door to more accessible medical delivery systems and economical widespread screening for disease. No region of the world would be too remote or too poor to receive high quality medical care. This article traces the development and current applications and initiatives in the field of telemedicine as applied to ophthalmology in the wider sense. Uses for clinical diagnosis and management, screening, research, education and peer interaction are discussed.
Sildenafil in primary pulmonary hypertension.
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Binding of camphor to Pseudomonas putida cytochrome p450(cam): steady-state and picosecond time-resolved fluorescence studies.
The binding of camphor to cytochrome P450(cam) has been investigated by steady-state and time-resolved tryptophan fluorescence spectroscopy to obtain information on the substrate access channel. The fluorescence quenching experiments show that some of the tryptophan residues undergo changes in their local environment on camphor binding. The time-resolved fluorescence decay profile gives four lifetime components in the range from 99 ps to 4.5 ns. The shortest lifetime component assigned to W42 lies close to the proposed camphor access channel. The results show that the fluorescence of W42 is greatly affected on binding of camphor, and supports dynamic fluctuations involved in the passage of camphor through the access channel as proposed earlier on the basis of crystallographic, molecular dynamics simulation and site-directed mutagenesis studies.
Genetic testing for hereditary hearing loss: connexin 26 (GJB2) allele variants and two novel deafness-causing mutations (R32C and 645-648delTAGA).
Mutations in GJB2 are the most common cause of hereditary congenital hearing loss in many countries and are found in about half of persons with severe-to-profound congenital autosomal recessive non-syndromic hearing loss (ARNSHL). We report the results of GJB2 mutation screening in 209 consecutive persons with congenital deafness of indeterminate etiology using an allele-specific polymerase chain reaction assay, single-strand conformational polymorphism analysis, and direct sequencing. GJB2 allele variants were detected in 74 of 209 deaf individuals (35%). Over one-fourth of screened individuals were either homozygous (n=31) or heterozygous (n=24) for the 35delG mutation. Of those with the 35delG mutation, 51 (92.7%) were diagnosed with GJB2-related deafness. Nineteen persons were identified with other GJB2 allele variants - two novel deafness-causing mutations (R32C, 645-648delTAGA), one mutation of unknown significance (E47K), and one benign polymorphism (I128I). While these data enable health care professionals to provide parents and patients with improved genetic counseling data, difficulty still exists is determining whether some missense mutations compromise auditory function and are deafness-causing.
Radiographic findings in tuberculosis of the calvarium.
We reviewed the pattern of involvement of the calvarium by tuberculosis (TB) in five patients and the role of imaging in its management. Four patients presented with localised scalp swelling and one with generalized seizures. Radiographs revealed lucent lesions with minimal surrounding sclerosis in the frontal (2), parietal (2) and occipital (1) bones. CT showed lesions involving the entire thickness of the calvarium and accompanying contrast-enhancing soft tissue. The patient presenting with seizures had a ring-enhancing lesion in the parietal lobe in addition to the extra-axial lesions. Although radiographs in all cases demonstrated calvarial TB, CT showed the extent of the defect, involvement of adjacent soft tissues, and in one case an intra-axial lesion. Radiographs suffice for follow-up of these patients.
Giant hypothalamic hamartoma with cystic change: report of two cases and review of the literature.
We describe the MRI findings in two patients with giant hypothalamic hamartomas with cystic areas. Cystic change within hypothalamic hamartomas is rarely reported in the literature.
Tuberculosis of the sternum and clavicle: imaging findings in 15 patients.
OBJECTIVE: To describe the imaging findings in sterno-clavicular tubercular involvement. DESIGN AND PATIENTS: Fifteen patients with pathologically proven tuberculosis of the sternum and clavicle were retrospectively evaluated. Routine radiography, computed tomography (CT) and magnetic resonance imaging (MRI) were used in some or all of the patients. Clinical information and imaging features were evaluated in each case. RESULTS: Eight patients had sternoclavicular joint (SCJ) involvement, five had isolated sternal involvement and two had isolated clavicular involvement. Seven patients were evaluated with only CT, six with only MRI and two with both. There were eight male and seven female patients, varying in age between 16 and 78 years. Fever, swelling and pain were common presenting symptoms. Two patients were HIV positive. Radiographs were positive in only eight patients. Destruction and signal intensity (SI) changes of the sternum and clavicle, destruction of the cartilage, soft tissue changes representing granulation tissue/abscess, displacement of the adjacent structures (vessels, trachea, etc.) and inflammatory changes in the adjacent structures in the form of cellulitis and myositis were common imaging features. CONCLUSIONS: All imaging methods can provide complementary information regarding sterno-clavicular tubercular involvement that is helpful for determination of the therapy. MRI is useful in determining the extent of the lesion, particularly marrow involvement and soft tissue extent.
Imaging in isolated sacral tuberculosis: a review of 15 cases.
OBJECTIVE: To review imaging studies of isolated involvement of the sacrum due to tuberculosis and determine the role of imaging in the diagnosis and management of these patients. DESIGN AND PATIENTS: A retrospective analysis of 15 cases of isolated sacral tuberculosis imaged with MR imaging was performed. The CT images were also reviewed where available, and the various lesion characteristics were identified. We also reviewed the medical records in an attempt to determine the impact of the imaging studies on the management of these patients. RESULTS: Fifteen patients (5 male, 10 female) presented with symptoms of 3-15 months' duration. Chronic localized backache with muscle spasm was the commonest presenting symptom; discharging sinuses with abscess formation was found in six patients, five of whom were children. MR imaging of the sacrum revealed a hypointense marrow signal on T1-weighted images and hyperintense signal on T2-weighted images in 14 of 15 patients, the S2 vertebra being always involved. CT revealed osteolytic changes in the sacrum in all the five patients in whom CT was performed. All patients showed marked clinical improvement within 1 year of anti-tuberculous chemotherapy. CONCLUSION: Isolated tuberculosis of the sacrum is uncommon but should be suspected in patients presenting with chronic low backache or children with discharging sinuses/abscesses and showing sacral destruction on CT or MR imaging. MR imaging can identify cases and enables early institution of antituberculous chemotherapy.
Refined localization and two additional linked families for the DFNA10 locus for nonsyndromic hearing impairment.
DFNA10 originally was mapped to the long arm of chromosome 6 in a large American family segregating for autosomal dominant progressive nonsyndromic hearing impairment. By extending this American family, we have reduced the original DFNA10 candidate region from 13 cM to 3.7 cM. We also report a Belgian family with autosomal dominant nonsyndromic hearing impairment linked to DFNA10 and a Norwegian family with the same condition in which linkage is suggestive, although maximum lod scores are only 2.5. The hearing phenotype in all three DFNA10 families is similar, with losses beginning in the middle frequencies and involving the low and high frequencies later in life.
The American Journal of Ophthalmology: electronic augmentation on the Internet.
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Phacoemulsification performed by residents.
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Phacoemulsification in a patient with marked cervical kyphosis.
A patient with long-standing ankylosing spondylitis and chronic uveitis needed cataract extraction in his only eye. Extensive spinal deformities, including cervical kyphosis, prevented him from being positioned satisfactorily for surgery using a routine head-end or temporal position for the surgeon. The best possible position for surgery was achieved using an orthopedic operating table, which allowed the patient's head to be reclined to a position of 60 degrees to the horizontal. Successful combined phacoemulsification and trabeculectomy was then performed, although the angle of approach for the surgeon and the operating microscope was awkward.
Should ophthalmology practices be online?
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Comments on the combined procedure.
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Visual outcome with the array multifocal intraocular lens in patients with concurrent eye disease.
PURPOSE: To evaluate whether the distance visual outcome with the Array(R) multifocal intraocular lens (IOL) is comparable to that of a monofocal IOL in eyes with concurrent disease and to assess whether these eyes benefit from the IOL's multifocality. SETTING: Department of Ophthalmology, Arrowe Park Hospital, Wirral, United Kingdom. METHODS: This prospective study comprised 133 eyes of 111 patients with cataract and concurrent disease such as macular degeneration, glaucoma, and diabetic retinopathy. Eighty-one eyes (70 patients) received an Array multifocal IOL after phacoemulsification. A control group of 52 eyes (41 patients) received a monofocal IOL of similar design (AMO SI-40NB). Visual outcomes in terms of uncorrected and best corrected distance and near acuities were evaluated. RESULTS: In both the multifocal and the monofocal IOL groups, the number of eyes achieving a best corrected visual acuity of 6/12 and N8 or better (55 and 37 eyes, respectively) was comparable (P > or =.999; 95% confidence interval [CI] -0.152 to 0.172). There was a borderline statistically significant difference in the number of eyes achieving an uncorrected visual acuity of 6/12 or better and N8 or better in the multifocal IOL (11 eyes) and monofocal (2 eyes) groups (P =.047, 95% CI -0.001 to 0.196). A significantly higher number of eyes in the multifocal group (40 eyes) than in the monofocal IOL group (4 eyes) achieved a distance-corrected acuity of 6/12 and N8 or better (P =.0001; 95% CI 0.274 to 0.539). CONCLUSIONS: The Array multifocal IOL produced distance visual outcomes comparable to those of the AMO SI-40NB monofocal IOL in patients with concurrent eye disease. A significant proportion of these patients benefited from the IOL's multifocality. Management of associated eye disease was not compromised by the nature of the IOL.
Lacrimal canalicular stenosis associated with systemic 5-fluorouacil therapy.
PURPOSE: Ocular side effects of systemic 5-fluorouracil therapy include excessive lacrimation which often resolves on cessation of therapy. Permanent stenosis of lacrimal puncta and canaliculi is rare. This report highlights this uncommon complication of 5-fluorouracil therapy. METHODS: Report of two cases and review of literature. RESULTS: Severe stenosis of puncta and canaliculi may be associated with prolonged systemic 5-fluorouracil therapy. CONCLUSION: It is important for both the oncologist and ophthalmologist to be aware of the potential ocular toxicity of 5-fluorouracil. Surgical management to relieve the epiphora is often challenging, and early intervention may be beneficial.