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Biomedical subjects

Mamta Fuloria

Publications and source records attributed to Mamta Fuloria.

8 recordsLinked to original sources
PubMed2004

20-hydroxyeicosatetraenoic acid is a vasoconstrictor in the newborn piglet pulmonary microcirculation.

20-Hydroxyeicosatetraenoic acid (20-HETE), a cytochrome p-450 metabolite of arachidonic acid, is a vasoconstrictor in the systemic circulation and a vasodilator in the adult pulmonary circulation. Little is known about the vasoactive properties of 20-HETE in the newborn pulmonary circulation. The objectives of this study were to determine the vascular effects of 20-HETE and to explore the signaling mechanism(s) that mediate these effects in newborn pulmonary resistance-level arteries (PRA). Our findings demonstrate that, in contrast to the adult pulmonary circulation where 20-HETE mediates vasodilation, it causes constriction in newborn PRA at resting tone. Furthermore, inhibition of cyclooxygenase (COX) with indomethacin augments 20-HETE-induced constriction. The enhanced constrictor response to 20-HETE under conditions of COX inhibition is abolished in endothelium-disrupted PRA, suggesting that 20-HETE either stimulates endothelium-derived COX to release a counteracting vasodilator or is rapidly metabolized by COX to a less potent vasoconstrictor. 20-HETE-induced constriction is significantly inhibited by blocking calcium-dependent K(+) (K(Ca)) channels and the thromboxane-PGH(2) receptor. Altogether, our data indicate that the vascular actions of 20-HETE are partially mediated via the activation of K(Ca) channels and are significantly modulated by interactions with the COX-prostaglandin pathway.

Animals↗
PubMed2004

Effect of meconium on the surface properties of perflubron.

OBJECTIVE: Meconium passage with pulmonary aspiration in utero is associated with surfactant inactivation and is a major cause of neonatal morbidity and mortality. Ventilation with low surface tension perfluorocarbon in animal models of meconium aspiration has been shown to improve both oxygenation and lung compliance. Exogenously administered surfactant is inactivated by meconium. We wished to determine whether meconium would alter the surface properties of perfluorooctyl bromide (perflubron). DESIGN: Biophysical analysis using novel methods. SETTING: University research laboratory. SUBJECTS: Healthy newborns. INTERVENTIONS: First pass meconium was obtained from healthy newborns. MEASUREMENTS AND MAIN RESULTS: We evaluated the surface-active properties of perflubron after exposure to meconium-saline dilutions using the de Noüy ring distraction technique to measure interfacial tension and the sessile contact angle of meconium-saline suspensions. Both were assessed in the absence and presence of perflubron. Meconium-saline suspensions inhibited surfactant activity. In contrast, the surface properties of perflubron were unaffected by the presence of meconium-saline suspensions. CONCLUSIONS: These data are consistent with reported observations of increased lung compliance in perfluorocarbon-treated animals with meconium aspiration. In addition to these clinical implications, the novel interfacial tension technique described here could prove useful for assessing the interfacial properties of other poorly miscible biological fluids.

Biological Products↗
PubMed2003

A randomized, controlled trial comparing two different continuous positive airway pressure systems for the successful extubation of extremely low birth weight infants.

OBJECTIVE: To determine whether the use of the Infant Flow continuous positive airway pressure (IF CPAP) system reduces the rate of extubation failure among extremely low birth weight (ELBW) infants (infants with birth weight <1000 g) when compared with conventional CPAP delivered with a conventional ventilator and nasal prongs. METHODS: A prospective, unmasked, randomized, controlled clinical trial was conducted in 162 eligible intubated ELBW infants who were hospitalized in 2 intensive care nurseries in Winston-Salem, North Carolina, between July 1997 and November 2000. Successful extubation was defined as no need for reintubation for any reason for at least 7 days after the first extubation attempt. RESULTS: The individual extubation success rates were 61.9% (52 of 84) in the conventional CPAP group and 61.5% (48 of 78) in the IF CPAP group. There were no significant differences in the extubation success rate in any birth weight subset between the 2 cohorts. The most common cause of extubation failure was apnea/bradycardia. Infants who were randomized to IF CPAP had fewer days on supplemental O(2) and shorter hospital stays. CONCLUSIONS: Extubation failure is a common problem, occurring in nearly 40% of ELBW infants who require mechanical ventilation. IF CPAP was as effective but no more effective than conventional CPAP in preventing extubation failure among ELBW infants. New strategies are needed to identify predictors of extubation success and to treat apnea/bradycardia, the most common cause of extubation failure, thereby reducing the likelihood of prolonged intubation in this high-risk cohort of premature infants.

Apnea↗
PubMed2002

The newborn examination: part II. Emergencies and common abnormalities involving the abdomen, pelvis, extremities, genitalia, and spine.

Careful examination of the neonate at delivery can detect anomalies, birth injuries, and disorders that may compromise successful adaptation to extrauterine life. A newborn with one anatomic malformation should be evaluated for associated anomalies. If a newborn is found to have an abdominal wall defect, management includes the application of a warm, moist, and sterile dressing over the defect, decompression of the gastrointestinal tract, aggressive fluid resuscitation, antibiotic therapy, and prompt surgical consultation. Hydroceles are managed conservatively, but inguinal hernias require surgical repair. A newborn with developmental hip dysplasia should be evaluated by an orthopedist, and treatment may require use of a Pavlik harness. The presence of ambiguous genitalia is a medical emergency, and pituitary and adrenal integrity must be established. Early diagnosis of spinal lesions is imperative because surgical correction can prevent irreversible neurologic damage.

Abdomen↗
PubMed2002

The newborn examination: part I. Emergencies and common abnormalities involving the skin, head, neck, chest, and respiratory and cardiovascular systems.

The routine newborn assessment should include an examination for size, macrocephaly or microcephaly, changes in skin color, signs of birth trauma, malformations, evidence of respiratory distress, level of arousal, posture, tone, presence of spontaneous movements, and symmetry of movements. A newborn with one anatomic malformation should be evaluated for associated anomalies. Total and direct bilirubin levels should be measured in newborns with jaundice, and a complete blood count should be obtained in those with pallor or a ruddy complexion. Neurosurgical consultation is necessary in infants with craniosynostosis accompanied by restricted brain growth or hydrocephalus, cephaloceles, or exophytic scalp nodules. Neck masses can be identified by their location and include vascular malformations, abnormal lymphatic tissue, teratomas, and dermoid cysts. Most facial nerve palsies resolve spontaneously. Conjunctivitis is relatively common in newborns. Infants with chest abnormalities may need to be evaluated for Poland's syndrome or Turner's syndrome. Murmurs in the immediate newborn period are usually innocent and represent a transition from fetal to neonatal circulation. Because cyanosis is primarily secondary to respiratory or cardiac causes, affected newborns should be evaluated expeditiously, with the involvement of a cardiologist or neonatologist.

Birth Injuries↗
PubMed2002

Mechanisms of bradykinin-mediated dilation in newborn piglet pulmonary conducting and resistance vessels.

Bradykinin (BK) is a potent dilator of the perinatal pulmonary circulation. We investigated segmental differences in BK-induced dilation in newborn pig large conducting pulmonary artery and vein rings and in pressurized pulmonary resistance arteries (PRA). In conducting pulmonary arteries and veins, BK-induced relaxation is abolished by endothelial disruption and by inhibition of nitric oxide (NO) synthase with nitro-L-arginine (L-NA). In PRA, two-thirds of the dilation response is L-NA insensitive. Charybdotoxin plus apamin and depolarization with KCl abolish the L-NA-insensitive dilations, findings that implicate the release of endothelium-derived hyperpolarizing factor (EDHF). However, endothelium-disrupted PRA retain the ability to dilate to BK but not to ACh or A-23187. In endothelium-disrupted PRA, dilation was inhibited by charybdotoxin. Thus in PRA, BK elicits dilation by multiple and duplicative signaling pathways. Release of NO and EDHF contributes to the response in endothelium-intact PRA; in endothelium-disrupted PRA, dilation occurs by direct activation of vascular smooth muscle calcium-dependent potassium channels. Redundant signaling pathways mediating pulmonary dilation to BK may be required to assure a smooth transition to extrauterine life.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed2002

Role of 5,6-epoxyeicosatrienoic acid in the regulation of newborn piglet pulmonary vascular tone.

We examined the responses of newborn piglet pulmonary resistance arteries (PRAs) to 5,6-epoxyeicosatrienoic acid (5,6-EET), a cytochrome P-450 metabolite of arachidonic acid. In PRAs preconstricted with a thromboxane A(2) mimetic, 5,6-EET caused a concentration-dependent dilation. This dilation was partially inhibited by the combination of charybdotoxin (CTX) and apamin, inhibitors of large and small conductance calcium-dependent potassium (K(Ca)) channels, and was abolished by depolarization of vascular smooth muscle with KCl. Disruption of the endothelium significantly attenuated the dilation, suggesting involvement of one or more endothelium-derived vasodilator pathways in this response. The dilation was partially inhibited by nitro-L-arginine (L-NA), an inhibitor of nitric oxide synthase (NOS), but was unaffected by indomethacin, a cyclooxygenase (COX) inhibitor. The combined inhibition of NOS and K(Ca) channels with L-NA, CTX, and apamin abolished 5,6-EET-mediated dilation. Similarly, combined inhibition of NOS and COX abolished the response. We conclude that 5,6-EET is a potent vasodilator in newborn piglet PRAs. This dilation is mediated by redundant pathways that include release of nitric oxide (NO) and COX metabolites and activation of K(Ca) channels. The endothelium dependence of this response suggests that 5,6-EET is not itself an endothelium-derived hyperpolarizing factor (EDHF) but may induce the release of one or more endothelium-derived relaxing factors, such as NO and/or EDHF.

8,11,14-Eicosatrienoic Acid↗