Biomedical subjects

Nehal A Parikh

Publications and source records attributed to Nehal A Parikh.

4 recordsLinked to original sources

PubMed2006

Effect of 7-nitroindazole sodium on the cellular distribution of neuronal nitric oxide synthase in the cerebral cortex of hypoxic newborn piglets.

Cerebral hypoxia results in generation of nitric oxide (NO) free radicals by Ca(++)-dependent activation of neuronal nitric oxide synthase (nNOS). The present study tests the hypothesis that the hypoxia-induced increased expression of nNOS in cortical neurons is mediated by NO. To test this hypothesis the cellular distribution of nNOS was determined immunohistochemically in the cerebral cortex of hypoxic newborn piglets with and without prior exposure to the selective nNOS inhibitor 7-nitroindazole sodium (7-NINA). Studies were conducted in newborn piglets, divided into normoxic (n = 6), normoxic treated with 7-NINA (n = 6), hypoxic (n = 6) and hypoxic pretreated with 7-NINA (n = 6). Hypoxia was induced by lowering the FiO(2) to 0.05-0.07 for 1 h. Cerebral tissue hypoxia was documented by decrease of ATP and phosphocreatine levels in both the hypoxic and 7-NINA pretreated hypoxic groups (P < 0.01). An increase in the number of nNOS immunoreactive neurons was observed in the frontal and parietal cortex of the hypoxic as compared to the normoxic groups (P < 0.05) which was attenuated by pretreatment with 7-NINA (P < 0.05 versus hypoxic). 7-NINA affected neither the cerebral energy metabolism nor the cellular distribution of nNOS in the cerebral cortex of normoxic animals. We conclude that nNOS expression in cortical neurons of hypoxic newborn piglets is NO-mediated. We speculate that nNOS inhibition by 7-NINA will protect against hypoxia-induced NO-mediated neuronal death.

Animals↗

PubMed2005

Diffusion tensor imaging of the developing human cerebrum.

Diffusion tensor imaging (DTI) was performed on 15 fresh spontaneously or therapeutically aborted normal fetuses and five term infants at different gestational ages. Regional cortical fractional anisotropy (FA) values were observed to increase with gestational age (GA) from 15 to 28 weeks, followed by a decrease through 36 weeks. The early increase in the cortical FA value, which has never been reported before, is consistent with neuronal migration from the germinal matrix. A statistically significant inverse correlation between GA and the FA values in the germinal matrix was observed (r = -0.81, P = 0.004). In addition, there was a significant difference in the FA values in the right and left frontal cortices (P = 0.007, sign test), suggesting cortical lateralization during the early stage of development. Our studies suggest that the DTI-estimated anisotropy could be useful in following neuronal migration, cortical maturation, and associated changes in the germinal matrix during early brain development.

Anisotropy↗

PubMed2005

The effects of early lead exposure on the brains of adult rhesus monkeys: a volumetric MRI study.

Little is known about direct effects of exposure to lead on central nervous system development. We conducted volumetric MRI studies in three groups of 17-year-old rhesus monkeys: (1) a group exposed to lead throughout gestation (n = 3), (2) a group exposed to lead through breast milk from birth to weaning (n = 4), and (3) a group not exposed to lead (n = 8). All fifteen monkeys were treated essentially identically since birth with the exception of lead exposure. The three-dimensional MRI images were segmented on a computer workstation using pre-tested manual and semi-automated algorithms to generate brain volumes for white matter, gray matter, cerebrospinal fluid, and component brain structures. The three groups differed significantly in the adjusted (for total brain size) volumes of the right cerebral white matter and the lateral ventricles. A significant reduction was noted in right cerebral white matter in prenatally exposed monkeys as compared to controls (p = 0.045). A similar reduction was detected in the white matter of the contralateral hemisphere; however, this difference did not achieve statistical significance (p = 0.143). Prenatally exposed monkeys also had larger right (p = 0.027) and left (p = 0.040) lateral ventricles. Depending on the timing of exposure during development, lead may exhibit differential effects with resultant life-long alterations in brain architecture.

Animals↗

PubMed2004

Effect of inhaled corticosteroids on markers of pulmonary inflammation and lung maturation in preterm infants with evolving chronic lung disease.

BACKGROUND: Chronic lung disease (CLD) is one of the most severely disabling conditions of extremely low-birth-weight infants. Systemic corticosteroids are effective but cause many adverse effects. Targeted therapy with inhaled corticosteroids may be an effective and less toxic alternative. STUDY OBJECTIVE: To evaluate the additive effect of inhaled corticosteroids on markers of lung inflammation in infants receiving a 7-day course of systemic steroids. METHODS: Preterm neonates weighing 1 kg or less and aged 12 to 28 days who were prescribed a 7-day course of systemic corticosteroids for evolving CLD were studied prospectively and randomized to receive either a tapering 4-week course of beclomethasone metered-dose inhaler (MDI) (n = 5) or placebo MDI (n = 6). Primary outcome variables were the levels of pro- and anti-inflammatory cytokines, IL-8, TNF-alpha, IL-1alpha, and sIL-2R. RESULTS: This study was terminated early following literature reports of the adverse neurodevelopmental effects of dexamethasone. Measurements of respiratory and serum IL-8, IL-1alpha and TNF-alpha were similar between the study group taking inhaled and systemic corticosteroids and the study group taking systemic steroids alone. No differences were found between the two groups in relation to dynamic compliance or resistance. CONCLUSIONS: The addition of inhaled corticosteroids to a 7-day systemic course of corticosteroids did not alter cytokine response or improve pulmonary function.

Administration, Inhalation↗