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Biomedical subjects

Arun Singh

Publications and source records attributed to Arun Singh.

9 recordsLinked to original sources
PubMed2006

Retinoblastoma.

Retinoblastoma, a neuroblastic tumor, is the most common primary intraocular malignancy of childhood. Patients usually present with leukokoria (white reflex or white pupil), detected in primary care. The mean age at diagnosis is 12 months for bilateral tumors and 24 months for unilateral tumors. If untreated, almost all patients die of intracranial extension and disseminated disease within two years. However, new diagnostic and treatment methods allow for a high cure rate (93 percent five-year survival in the United States), therefore it is important that primary care physicians recognize the manifestations of this malignancy. Diagnosis is primarily by history and complete ophthalmic examination, with studies including ultrasonography of the eye and imaging of the orbits and brain. Treatment modalities include laser thermotherapy, cryotherapy, radioactive plaques, external beam radiotherapy, chemotherapy, and enucleation. Prospective parents with a family history of retinoblastoma should be referred for genetic counseling. Office evaluation for a red reflex in children should be performed until three years of age. If leukokoria is observed, the patient should be examined by an ophthalmologist within one week.

Combined Modality Therapy↗
PubMed2004

Upregulation of the androgen receptor during prostate cancer progression.

The androgen receptor is one of the central factors in mediating prostate cancer progression and is an important target for treatment. Several possible mechanisms have been put forth as to how it promotes this process. In the January 2004 issue of Nature Medicine, Chen et al. report that the androgen receptor is consistently upregulated as hormone sensitive prostate cancer changes to a hormone refractory state. They also show that this change is intricately involved during the development of resistance to androgen ablation therapy.

Disease Progression↗
PubMed2004

Inotropes improve right heart function in patients undergoing aortic valve replacement for aortic stenosis.

UNLABELLED: The administration of inotropes after aortic valve replacement (AVR) for aortic stenosis (AS) is controversial. Issues include the risk of left ventricular (LV) systolic outflow obstruction (LVOTO) and the proper treatment of diastolic dysfunction for patients in whom LV systolic function is often preserved and subsequently improved. In this study, we assessed the hemodynamic benefits of inotropes for patients undergoing AVR for AS. Thirty-four patients were prospectively randomized to one of three groups: epinephrine, milrinone, or placebo. Hemodynamic and echocardiographic data were obtained before and immediately after cardiopulmonary bypass (CPB). Data were also obtained before and after increases in ventricular preload to assess the effects of inotropes on diastolic function. The use of inotropes was associated with significantly larger increases in right ventricular (RV) (placebo, 0.5%; epinephrine, +9%; milrinone, +8%; P < 0.01) and LV (placebo, +7%; epinephrine, +18%; milrinone, +20%; P = 0.07) ejection fractions (EF) and cardiac output after CPB. Changes in cardiac output and index were more strongly correlated with changes in RVEF (r = 0.56, P < 0.01; r = 0.47, P < 0.01, respectively) than with LVEF (r = 0.22, r = 0.08). Of all patients receiving epinephrine or milrinone, only one (1 of 22) had a decrease in RVEF, whereas 6 of 12 patients receiving placebo had a reduction in RVEF from pre-CPB to post-CPB. Correspondingly, for LVEF, 1 of 22 patients receiving inotropes had a decrease in LVEF, whereas 3 of 12 placebo patients had a reduction in LVEF from pre-CPB to post-CPB. No patient had evidence of LVOTO. Inotropes improved hemodynamics after AVR for AS. This was attributable more to improved RV function than to changes in LV function. Although there were no changes in diastolic function, it is possible that this study did not allow significant timing to observe benefits of inotropes on diastolic function in this setting. IMPLICATIONS: Compared with placebo, both epinephrine and milrinone similarly improved biventricular performance after aortic valve replacement, with a greater impact on right ventricular function. Choice of either inotropic drug should be driven by blood pressure and hemodynamic goals in this setting.

Adrenergic alpha-Agonists↗
PubMed2003

RT-PCR for PSA as a prognostic factor for patients with clinically localized prostate cancer treated with radiotherapy.

OBJECTIVES: To study prospectively the prognostic significance of the reverse transcriptase-polymerase chain reaction (RT-PCR) assay for patients with prostate cancer treated definitively with external beam radiotherapy. The RT-PCR assay for prostate-specific antigen (PSA) has been used to detect circulating prostate cancer cells in the serum of patients with prostate cancer. METHODS: In prospective fashion, serum RT-PCR testing was performed before and/or after definitive therapy, with the results scored as positive or negative. The results were analyzed for 161 patients, and the RT-PCR result was correlated with the treatment outcome. RESULTS: The median follow-up was 29 months. The pretreatment RT-PCR result was not predictive of biochemical relapse-free survival (bRFS) or clinical disease-free survival (DFS). Of 25 patients with T3-T4 tumors, those with a negative pretreatment RT-PCR result had better bRFS and a trend was noted toward better DFS compared with those with a positive result. Among patients with Gleason score 8 to 10 tumor who underwent pretreatment testing (n = 19), those with a negative RT-PCR result had better bRFS and DFS compared with those with a positive result. A trend toward better bRFS was seen for patients with negative versus positive post-treatment RT-PCR results. The DFS was better for patients with negative versus positive post-treatment RT-PCR results. CONCLUSIONS: RT-PCR, when obtained before radiotherapy, may be predictive of outcome for patients with more advanced stages or higher Gleason scores. Post-treatment testing predicted for clinical relapse. Additional study is needed before RT-PCR is used regularly in clinical practice.

Androgen Antagonists↗
PubMed2002

Chemoreduction plus focal therapy for retinoblastoma: factors predictive of need for treatment with external beam radiotherapy or enucleation.

PURPOSE: To report the results of chemoreduction and focal therapy for retinoblastoma with determination of factors predictive of the need for treatment with external beam radiotherapy or enucleation. DESIGN: Interventional case series. METHODS: One-hundred three patients with retinoblastoma (158 eyes with 364 tumors) at the Ocular Oncology Service at Wills Eye Hospital of Thomas Jefferson University in conjunction with the Division of Oncology at Children's Hospital of Philadelphia from June 1994 to August 1999 were enrolled for this prospective clinical trial. The patients received treatment for retinoblastoma with six planned cycles (one cycle per month) of chemoreduction using vincristine, etoposide, and carboplatin combined with focal treatments (cryotherapy, thermotherapy, or plaque radiotherapy). The two main outcome measures after chemoreduction and focal therapy were the need for external beam radiotherapy and the need for enucleation. The clinical features at the time of patient presentation were analyzed for impact on the main outcome measures using a series of Cox proportional hazards regressions. RESULTS: Using Reese-Ellsworth (RE) staging for retinoblastoma, there were nine (6%) eyes with group I disease, 26 (16%) eyes with group II disease, 16 (10%) eyes with group III disease, 32 (20%) eyes with group IV disease, and 75 (48%) eyes with group V retinoblastoma. All eyes showed initial favorable response with tumor regression. The median follow-up was 28 months (range, 2-63 months). Failure of chemoreduction and need for treatment with external beam radiotherapy occurred in 25% of eyes at 1 year, 27% at 3 years, and no further increase at 5 years. More specifically, external beam radiotherapy was necessary at 5 years in 10% of RE groups I-IV eyes and 47% of RE group V eyes. Multivariate factors predictive of treatment with external beam radiotherapy included non-Caucasian race, male sex, and RE group V disease. Failure of chemoreduction and the need for treatment with enucleation occurred in 13% eyes at 1 year, 29% at 3 years, and 34% at 5 years. More specifically, enucleation was necessary in 15% of RE groups I-IV eyes at 5 years and in 53% of RE group V at 5 years. Multivariate factors predictive of treatment with enucleation included patient age older than 12 months, single tumor in eye, and tumor proximity to foveola within 2 mm. Overall, of the 158 eyes, 50% required external beam radiotherapy or enucleation and 50% were successfully managed without these treatments. No patient developed retinoblastoma metastasis, pinealoblastoma, or second malignant neoplasms over the 5-year follow up. CONCLUSIONS: Chemoreduction offers satisfactory retinoblastoma control for RE groups I-IV eyes, with treatment failure necessitating additional external beam radiotherapy in only 10% of eyes and enucleation in 15% of eyes at 5-year follow-up. Patients with RE group V eyes require external beam radiotherapy in 47% and enucleation in 53% at 5 years.

Antineoplastic Combined Chemotherapy Protocols↗
PubMedDate not supplied

Acute myocardial infarction due to blunt chest trauma.

We report a case of blunt chest injury following a road accident leading to damage of the left main and left anterior descending coronary arteries causing acute myocardial infarction in a young person.

Accidents, Traffic↗