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Biomedical subjects

T Sharma

Publications and source records attributed to T Sharma.

At least 55 records · Page 3Linked to original sources

Ultrasound biomicroscopy in the diagnosis and management of pars planitis caused by caterpillar hairs.

PURPOSE: To report the use of ultrasound biomicroscopy in the detection of caterpillar hairs in the pars plana in a patient with unilateral pars planitis. METHOD: Ultrasound biomicroscopic imaging of the anterior segment of the eye. RESULTS: Ultrasound biomicroscopy located a hair in the posterior chamber at the first visit and five more in the pars plana 1 month later. This finding was confirmed intraoperatively. CONCLUSION: Ultrasound biomicroscopy is useful in the diagnosis and management of unilateral pars planitis of uncertain cause.

Animals↗

Ultrasound biomicroscopy of sclerotomy sites after pars plana vitrectomy for diabetic vitreous hemorrhage.

OBJECTIVE: This study was aimed at assessing changes at the sclerotomy site using the ultrasound biomicroscope (UBM) in eyes that underwent primary pars plana vitrectomy for complications of proliferative diabetic retinopathy. DESIGN: Prospective, observational case series. PARTICIPANTS: Eighty-six eyes of 84 patients with vitreous hemorrhage caused by proliferative diabetic retinopathy. INTERVENTION: Three-port pars plana vitrectomy followed by UBM evaluation of all sclerotomy sites between 6 and 8 weeks after surgery. Correlation with intraoperative findings done in case of reoperations. Forty-one eyes had repeat UBM at 6 months. MAIN OUTCOME MEASURES: The changes at the sclerotomy site were classified into six groups: well healed, gape, plaque, vitreous incarceration, fibrovascular proliferation, and anterior hyaloidal fibrovascular proliferation (AHFVP). The UBM characteristics of each of the groups were defined. The findings at 6 months were compared with those at 6 to 8 weeks. RESULTS: At 6 to 8 weeks after surgery, most sclerotomies were well healed or had either moderate to high reflective plaques bridging the site. Wound gape was seen in 22.1% of active ports, 32.6% of light ports, and 25.6% of infusion ports. Vitreous incarceration was seen most often at the infusion port (18. 6% of eyes). Fibrovascular proliferation was seen in 9.3% of active ports, 12.8% of light ports, and 15.1% of infusion ports. Thirteen eyes had recurrent vitreous hemorrhage 6 to 8 weeks after surgery. Cases with rebleeding and no fibrovascular proliferation at the sclerotomy on UBM did well with outpatient fluid-air exchange (two eyes) or observation only (three eyes). Those with fibrovascular proliferation on UBM (eight eyes) required more extensive surgery. CONCLUSIONS: UBM is helpful in detecting complications at the sclerotomy sites after pars plana vitrectomy and is an invaluable tool in the assessment of the patient before reoperation.

Diabetic Retinopathy↗

Audit of small-incision cataract surgery using an anterior chamber maintainer.

PURPOSE: To assess the results of small-incision cataract surgery with intraocular lens implantation using an anterior chamber maintainer (ACM) performed between March 1997 and December 1998. METHOD: A retrospective audit was performed of all 300 consecutive patients who underwent extracapsular cataract extraction using a 6 mm scleral tunnel incision, anterior chamber maintainer and manual fragmentation of the nucleus. RESULTS: Ninety per cent of patients had a gain in visual acuity at the end of 3 months. The rate of posterior capsule opacification was comparable to the results of the National Cataract Surgery Survey (RCO 1993), i.e. 13%, but the rate of corneal endothelial decompensation and endophthalmitis was marginally higher. CONCLUSION: Appropriate selection of cases, meticulous wound closure and subconjunctival antibiotics at the end of surgery make this an acceptable alternative small-incision closed-system low-cost procedure where phacoemulsification is not available.

Adult↗

Mapping morphology of the corpus callosum in schizophrenia.

The nature and extent of callosal morphological alterations in schizophrenia remain unresolved. A parametric surface modeling approach using magnetic resonance (MR) images was employed. This provided spatially accurate representations of midsagittal callosal surfaces in schizophrenic patients (n = 25; 15 males) and normal controls (n = 28; 15 males). Areas of functionally relevant callosal channels and measures reflecting callosal shape were visualized and compared across groups. To register neuroanatomical landmarks surrounding the corpus callosum, each three-dimensional MR volume was scaled according to Talairach AC-PC distance, and raw distances included as covariates in multivariate analyses. Results revealed: (i) a marked vertical displacement of the corpus callosum in patients (P < 0.01); (ii) increases in curvature of superior and inferior callosal surfaces (P < 0.001); and (iii) significant increases in maximum widths in anterior and posterior regions in male patients compared to male controls; as well as (iv) increased patterns of callosal variability in female patients but no effects of diagnosis between female groups. These findings demonstrate a clear index of structural neuropathology in male schizophrenic patients. Displacement and curvature increases were highly correlated with structural differences in surrounding neuroanatomical regions, including increased volume of the lateral ventricles (P < 0.01).

Adult↗

Endolaser around macular hole in the management of associated retinal detachment in highly myopic eyes.

PURPOSE: To analyze the role of endolaser around macular hole in managing associated retinal detachment in patients with high myopia. METHODS: Review of medical records of 25 consecutive eyes of 25 patients with at least 5.00 diopters of myopia who underwent primary pars plana vitrectomy and fluid-gas exchange. In the first half of the study period, one row of contiguous argon green endolaser was routinely applied over the retinal edge of the macular hole (EL group). In the second half of the study period, endolaser was not applied around any macular hole (NEL group). Demographic information, intraoperative and postoperative complications, and final visual acuities and retinal reattachment rates were studied. RESULTS: The mean (+/-SD) refractive error was -11.8 +/- -3.5 diopters (D) for the EL group and -11.6 +/- -5.4 D for the NEL group. The mean axial length was 29.0 +/- 1.8 mm for the EL group and 28.3 +/- 1.7 mm for the NEL group. The primary anatomic success was 62.5% (10/16) and 77.8% (7/9) in the EL and NEL groups, respectively. No statistically significant difference was found in preoperative, postoperative, or change in best-corrected visual acuities between the two groups. CONCLUSION: Endolaser around the macular hole after pars plana vitrectomy and internal gas tamponade may not affect the anatomic or visual outcome in primary retinal detachment secondary to a highly myopic macular hole.

Adult↗

Sequential meiotic prophase development in the pubertal Indian pygmy field mouse: synaptic progression of the XY chromosomes, autosomal heterochromatin, and pericentric inversions.

Sequential meiotic prophase development has been followed in the pubertal male pygmy mouse Mus terricolor, with the objective to identify early meiotic prophase stages. The pygmy mouse differs from the common mouse by having large heterochromatic blocks in the X and Y chromosomes. These mice also show various chromosomal mutations; for example, fixed variations of autosomal short arms heterochromatin among different chromosomal species and pericentric inversion polymorphism. Identification of prophase stages was crucial to analyzing effects of heterozygosity for these chromosomal changes on the process of homologous synapsis. Here we describe identification of the prophase stages in M. terricolor, especially the pachytene substages, on the basis of morphology of the XY bivalent. Based on this substaging, we show delayed pairing of the heterochromatic short arms, which may be the reason for their lack of chiasmata. The identification of precise pachytene substages also reveals an early occurrence of "synaptic adjustment" in the pericentric inversion heterobivalents, a mechanism that would prevent chiasma formation in the inverted segment and thereby would abate adverse effects of such heterozygosity. The identification of pachytene substages would serve as the basis to analyze the nature of synaptic anomalies met in M. terricolor hybrids (which will be the basis of a subsequent paper).

Animals↗

Dynamic of nucleolus organizer regions and karyotype evolution in Indian pygmy field mice.

Ag-NOR staining and fluorescence in situ hybridization with rDNA probes showed an unusually high number of NORs in the Indian pygmy field mice, Mus booduga and the M. terricolor complex. The chromosomal location of the NORs was also altered in terricolor, they were shifted from the proximal regions of the long arms to the tips of the perceptible heterochromatic short arms of the acrocentric autosomes. The results suggested dispersion of the NORs in the booduga-terricolor lineage probably by transposition, and relocalization of the NORs in the terricolor complex by centric reorganization during the process of replacement of the Mus musculus-related AT-rich heterochromatin with the terricolor-specific heterochromatin.

Animals↗

Features of structural brain abnormality detected in first-episode psychosis.

OBJECTIVE: Structural magnetic resonance imaging (MRI) studies that focus on first-episode psychosis avoid some common confounds, such as chronicity of illness, treatment effects, and long-term substance abuse. However, such studies may select subjects with poor short-term treatment response or outcome. In this study, the authors focus on structural brain abnormalities in never or minimally treated patients who underwent MRI scanning early in their first episode of psychosis. METHOD: The authors examined 37 patients (13 medication naive, 24 previously treated) who were experiencing their first episode of psychosis; the mean duration of symptoms was short (31 weeks). These patients were comparable in age, gender, handedness, ethnicity, and parental socioeconomic status to a group of 25 healthy comparison subjects. A three-dimensional, inversion recovery prepared, fast spoiled gradient/recall in the steady state scan of the whole brain that used 1.5-mm contiguous sections was performed to acquire a T(1)-weighted data set. Human ratings of volumetric measurement of brain structures were performed with stereological techniques on three-dimensional reconstructed MRIs. RESULTS: The patient group had significant deficits in cortical gray matter, temporal lobe gray matter, and whole brain volume as well as significant enlargement of the lateral and third ventricles. Structural deviations were found in both treatment-naive and minimally treated subjects. No relationships were found between any brain matter volumes and positive or negative symptoms. CONCLUSIONS: Structural brain abnormalities were distributed throughout the cortex with particular decrement evident in gray matter. This feature is consistent with altered cell structure and disturbed neuronal connectivity, which accounts for the functional abnormality of psychosis.

Adult↗

Exploring the social brain in schizophrenia: left prefrontal underactivation during mental state attribution.

OBJECTIVE: Evidence suggests that patients with schizophrenia have a deficit in "theory of mind," i.e., interpretation of the mental state of others. The authors used functional magnetic resonance imaging (MRI) to investigate the hypothesis that patients with schizophrenia have a dysfunction in brain regions responsible for mental state attribution. METHOD: Mean brain activation in five male patients with schizophrenia was compared to that in seven comparison subjects during performance of a task involving attribution of mental state. RESULTS: During performance of the mental state attribution task, the patients made more errors and showed less blood-oxygen-level-dependent signal in the left inferior frontal gyrus. CONCLUSIONS: To the authors' knowledge, this is the first functional MRI study to show a deficit in the left prefrontal cortex in schizophrenia during a socioemotional task.

Adult↗

Sex differences in inferior parietal lobule volume in schizophrenia.

OBJECTIVE: The inferior parietal lobule is a heteromodal association cortical region that has been implicated in the pathophysiology of schizophrenia. Inferior parietal lobule gray matter volumes have been shown to differ between healthy male and female subjects, with male subjects having larger left volumes. The authors sought to determine whether these volumetric sex differences also exist in patients with schizophrenia. METHOD: The authors used magnetic resonance imaging to measure inferior parietal lobule volumes of 15 pairs of male and female schizophrenic subjects who were individually matched to each other and to 15 pairs of healthy male and female subjects. RESULTS: Male schizophrenic patients exhibited a reversal of the normal left-greater-than-right male asymmetry in this region and had left inferior parietal lobule gray matter volumes that were significantly smaller than those of healthy male subjects. Female schizophrenic patients did not differ significantly from healthy female subjects in left or right inferior parietal lobule volume or in asymmetry. CONCLUSIONS: This study provides further evidence of brain morphology sex differences in schizophrenia that possibly contribute to the differential clinical disease expression in men and women.

Age Factors↗

Functional anatomy of verbal fluency in people with schizophrenia and those at genetic risk. Focal dysfunction and distributed disconnectivity reappraised.

BACKGROUND: PET studies of verbal fluency in schizophrenia report a failure of 'deactivation' of left superior temporal gyrus (STG) in the presence of activation of left dorsolateral prefrontal cortex (DLPFC), which deficit has been attributed to underlying 'functional disconnectivity'. AIM: To test whether these findings provide trait-markers for schizophrenia. METHOD: We used H2(15)O PET to examine verbal fluency in 10 obligate carriers of the predisposition to schizophrenia, 10 stable patients and 10 normal controls. RESULTS: We found no evidence of a failure of left STG deactivation in carriers or patients. Instead, patients failed to deactivate the precuneus relative to other groups. We found no differences in functional connectivity between left DLPFC and left STG but patients exhibited significant disconnectivity between left DLPFC and anterior cingulate cortex. CONCLUSIONS: Failure of left STG 'deactivation' and left fronto-temporal disconnectivity are not consistent findings in schizophrenia; neither are they trait-markers for genetic risk. Prefrontal functional disconnectivity here may characterise the schizophrenic phenotype.

Heterozygote↗

Third ventricle enlargement and developmental delay in first-episode psychosis: preliminary findings.

BACKGROUND: Third rather than lateral ventriculomegaly may be a more specific finding in psychosis. The relevance of ventricular abnormality remains unclear. AIMS: To investigate the developmental correlates of ventricular enlargement. METHOD: Information on childhood development and magnetic resonance images in 1.5-mm contiguous sections were collected on 21 patients experiencing a first episode of psychosis. RESULTS: Patients (n = 21) had significantly less whole brain volume and enlarged third and lateral ventricles compared to controls (n = 25). Third ventricle (r = 0.48, P < 0.03) and lateral ventricle (r = 0.65, P < 0.01) volumes correlated with developmental score. Patients with developmental delay had significantly larger third and lateral ventricles than those without. CONCLUSIONS: Enlargement of both third and lateral ventricles is found in first-episode psychosis and is related to developmental delay in childhood. Insult to periventricular areas is relevant to the neurobiology of the disease. These findings support the view that schizophrenia involves disturbance of neurodevelopmental processes in some patients.

Adolescent↗

Experience of caregiving: relatives of people experiencing a first episode of psychosis.

BACKGROUND: There has been relatively little research on caregivers of people experiencing their first episode of psychosis. AIMS: To investigate dimensions of caregiving and morbidity in caregivers of people with first-episode psychosis. METHOD: Caregivers of 40 people with first-episode psychosis were interviewed at home about their experience of caregiving, coping strategies and distress. RESULTS: Caregivers used emotional and practical strategies to cope with participants' negative symptoms and difficult behaviours and experienced more worry about these problems. They increased supervision when the participants displayed difficult behaviours. Twelve per cent of caregivers were suffering from psychiatric morbidity as defined by the General Health Questionnaire. Those living with the participant had more frequent visits to their general practitioner. CONCLUSIONS: At first-episode psychosis, caregivers are already having to cope with a wide range of problems and are developing coping strategies. Caregivers worried most about difficult behaviours and negative symptoms in participants.

Adaptation, Psychological↗

The relevance of ethnic influences on pharmacogenetics to the treatment of psychosis.

Interethnic variation amongst the drug metabolising enzymes relevant to the treatment of psychosis is reviewed. The frequency of genetically determined variants at the extremes of enzyme activity is seen to vary considerably between different ethnic groups; in addition, a shift in the frequency distribution giving an overall lower population mean activity may occur. The role of dietary and other environmental influences in the generation of interethnic variation in cytochrome activity is also discussed. Clinical studies pertinent to this variation are reviewed. It is suggested that the reason for conflicting data from some clinical studies is the existence of overlapping substrate specificity, so that one cytochrome is able to substitute for another. Individuals deficient for more than one cytochrome would be likely to show much more pronounced clinical effects than those showing single cytochrome deficiency.

Antipsychotic Agents↗

Surgery for stage 5 retinopathy of prematurity: the learning curve and evolving technique.

PURPOSE: To describe our experience with management of eyes with stage 5 retinopathy of prematurity (ROP). METHODS: Closed vitreoretinal surgery was done on 96 eyes of patients with stage 5 ROP. Lens was sacrificed in all but one eye. Surgery involved an attempt to clear all preretinal tissue and open the peripheral trough all round. In most instances bimanual surgery under viscoelastic was performed. RESULTS: At last follow up, anatomical success (defined as attached posterior pole) was achieved in 22.5% cases. Significant postoperative problems included reproliferation and secondary glaucoma. Only two infants obtained mobile vision. CONCLUSION: Late identification of disease, lack of prior treatment such as laser or cryo, and higher incidence of narrow-narrow funnel configuration were responsible for the poor surgical results noted in this series. The poor surgical and functional results reemphasize the need for prompt screening and management of infants at risk.

Clinical Competence↗

Albendazole therapy for a recurrent orbital hydatid cyst.

Till recently, the treatment of a multiloculated hydatid cyst in the confines of the orbit was every ophthalmologist's nightmare. Over the last decade, two benzimidazole compounds, mebendazole and albendazole, have been tested clinically for use in the chemotherapy of hydatid disease.

Adolescent↗

Intraocular cilia associated with perforating injury.

PURPOSE: To report a case series of penetrating injury complicated by occurrence of intraocular cilia. METHODS: Retrospective analysis of charts of 11 eyes of 11 patients with penetrating injury and intraocular cilia, presenting between September 1978 and November 1998. Ten eyes underwent surgery for trauma-related problems such as cataract, vitritis, retinal detachment etc., at which time intraocular cilia were removed. One eye did not have surgery and continues to harbour cilia at the posterior perforation site. RESULTS: Metallic wire was responsible for injury in 6 of 11 eyes with intraocular cilia. Five eyes had significant intraocular inflammation. The cilia were located in the anterior segment in 4 eyes; in the posterior segment in 6 eyes and in both in one eye. At the last follow up, 72.7% had 6/18 or better vision. Poor vision in the rest was due to recurrent retinal detachment (2 eyes) and macular scarring (1 eye). CONCLUSION: Intraocular cilia are more commonly associated with injury by a metallic wire. The presentation and management of an injured eye does not seem to be influenced by the presence of cilia in the eye.

Adolescent↗