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Biomedical subjects

D Vidyasagar

Publications and source records attributed to D Vidyasagar.

At least 37 records · Page 2Linked to original sources
PubMed1997

Mechanics and energetics of nutritive sucking: a functional comparison of commercially available nipples.

The purpose of this study was to compare the mechanics of sucking for 48 term infants with four different nipple units: Gerber Newborn (Gerber Products Company, Fremont, Mich.), Playtex (Playtex Products, Westport, Conn.), Evenflo (Evenflo Products Co., Canton, Ga.), and Gerber NUK. At 24 hours after birth, infants were assigned randomly to one of the nipple units and were studied twice with that nipple unit. A customized data acquisition system was used to measure and record the following variables: intraoral suction, sucking frequency, work, power, milk flow, milk volume per suck, and oxygen saturation. Although no statistically significant differences among the nipple units were noted for intraoral suction, sucking frequency, power, and oxygen saturation, the data revealed that the Playtex nipple unit was accompanied by higher peak milk flow and greater volume of milk per suck (p < 0.05). Infants fed differently with the Playtex nipple than they did with the other nipples. Our findings indicate that the Playtex nipple permits a greater milk flow in response to similar amounts of suction, work, and power when compared with others. The mean total work per such was significantly lower in the Gerber NUK group compared with the Playtex group. In addition, the total number of sucks per volume ingested was higher, and the total time to ingest a specific quantity of milk was longer for the Gerber NUK nipple.

Biomechanical Phenomena↗
PubMed1997

Critical care in India.

India is a vast democracy of nearly one billion people. Before the British rule ended in 1947, the life span of an Indian was a mere 21 years. Within a short span of 50 years, it increased to an impressive 63 years, largely due to public health measures initiated by the government. This created a pool of more than 300 million middle class Indians who could afford the benefits of modern and specialized care when needed. Critical care medicine, as practiced in the West, is still confined to large Metropolitan areas. A large pool of expatriate Indian physicians from all over the world are helping bridge the resource gap between the West and India by transfer of technology and providing appropriate training to physicians and paramedical personnel. This article describes the history and current status of development of critical care medicine in India.

Critical Care↗
PubMed1997

Evolution of neonatal and pediatric critical care in India.

During the last decade, the disciplines of neonatal and pediatric critical care have rapidly progressed in India. The growth of Neonatal Intensive Care has paced the growth of Pediatric Critical Care. The substantial growth of discipline and the positive improvements in neonatal outcomes are the results of the concerted efforts of the National Neonatal Forum and commitment of expatriate physicians residing in the United States. This article provides the background information regarding perinatal, neonatal, and infant mortalities in India. It also describes the maternal child health care delivery system in the Indian subcontinent.

Child↗
PubMed1997

Bile flow and composition in preterm, term and infant baboons.

UNLABELLED: We studied the maturational changes in bile composition, bile flow and choleretic effects of sodium taurocholate and secretin in preterm (160 +/- 2 days, n = 4, group I), term (184 +/- 2 days, n = 4, group II), 7-day postnatal age (n = 5, group III) and 60-day-old (n = 5, group IV) baboons. The canalicular bile flow was determined by 14C-erythritol clearance. RESULTS: Gall bladder volume increased from group I to group III (0.08 +/- 0.06 to 1.06 +/- 0.93 ml). Bile flow increased significantly from group I to IV (0.13 +/- 0.05 to 0.34 +/- 0.07 microliter/min/g liver weight, p < 0.05). This was associated with significant increases in total bile acid excretion (16 +/- 3.6 to 31 +/- 2.5 mEq/l, p < 0.05). The composition of bile also showed maturational changes with increasing postnatal age. Sodium taurocholate and secretin increased the bile flow significantly in all groups. CONCLUSION: Data from these studies clearly demonstrate that the bile flow and bile acid excretion is immature in preterm and term baboons when compared to 7- and 60-day-old baboons. The present studies also suggest that baboons can be used as a model to study the postnatal maturation of hepatic excretory function.

Animals↗
PubMed1996

Chloride transport in primary cultures of rabbit colonocytes at different stages of development.

BACKGROUND & AIMS: Ontogeny of colonic Cl- transport and its regulation has been characterized inadequately. The aim of this report was to study developmental changes in Cl- transport in primary cultures of rabbit distal colonocytes. METHODS: Colonocytes from newborn (7-9 days old), weanling (25-28 days old), and adult (6 months old) rabbits were cultured for 24 hours on a collagen IV matrix, and Cl- transport was measured using the fluoroprobe 6-methoxyquinolyl acetoethyl ester. RESULTS: Cl- permeabilities were dependent on [Cl-]o with maximal rates (in millimoles per liter per second) at [Cl-]o = 75 mmol/L (newborns; 0.15 +/- 0.04; weanlings; 0.2 +/- 0.02; and adults, 0.32 +/- 0.06). Influx was inhibited significantly by the Cl- channel (50 mumol/L diphenylamine-2-carboxylate) and the Na(+)-K(+)- 2Cl- cotransport (10 mumol/L furosemide) inhibitors. The adenosine 3',5'-cyclic monophosphate (cAMP)-dependent secretagogues, prostaglandin E1 (1 mumol/L), forskolin (1 mumol/L), and 8-bromo-cAMP (100 mumol/L), and the protein kinase C activator, phorbol 12-13 dibutyrate (1 mumol/L), increased Cl- influx significantly in all groups with adults showing greatest stimulation. However, taurodeoxycholate (0.025-1 mmol/L) had an effect only in the adult and the guanosine 3',5'-cyclic monophosphate (cGMP) activators STa and 8-bromo-cGMP had no effect. CONCLUSIONS: Rabbit distal colonocytes possess inhibitor-sensitive Cl- permeabilities even in neonates. However, the ontogeny of their regulation depends on the secretagogue-signaling pathway.

Animals↗
PubMed1996

Vitamin A deficiency and severe bronchopulmonary dysplasia in very low birthweight infants.

Preterm infants often have abnormally low serum vitamin A concentrations. Persistence of vitamin A deficiency for a prolonged postnatal period may contribute to the development of bronchopulmonary dysplasia. We retrospectively analyzed data from 22 infants with birthweight < or = 1250 g who had hyaline membrane disease requiring mechanical ventilation with oxygen and in whom serum vitamin A concentrations had been measured at the onset of enteral feeding and every 2 weeks thereafter. Thirteen infants (low serum vitamin A group) had one or more serum vitamin A concentrations < or = 11 mcg/dL at > 10 days of age. In 9 infants (higher serum vitamin A group) all serum vitamin A concentrations were > 11 mcg/dL at > 10 days of age. Mean birthweight, mean gestational age, sex, race, incidence of antenatal maternal glucocorticoid treatment and ventilatory support on the first day of life were similar for the two groups. Severe bronchopulmonary dysplasia was as defined as characteristic radiographic changes and either discharge from the hospital with supplemental oxygen or death from respiratory failure at > 28 days of age following mechanical ventilation with oxygen since birth. The incidence of severe bronchopulmonary dysplasia was significantly higher in the low serum vitamin A group (11/13, 3 deaths vs. 1/9, no deaths; p=0.001). The incidence of pulmonary air leak, the number of ventilator days, the number of days of postnatal glucocorticoid treatment for chronic lung disease, the number of episodes of suspected sepsis and the number of days of antibiotic treatment also were higher in the low serum vitamin A group. Low serum vitamin A group infants were older at the onset of enteral feeding (21 days vs. 8 days; p = 0.001) and during feeding their average daily enteral intake of vitamin A was lower (713 IU vs. 1255 IU; p = 0.001) when compared with infants in the higher serum vitamin A group. Our retrospective analysis of data from these infants confirms earlier reports from other workers that persistent marked vitamin A deficiency in very low birthweight infants is associated with a high incidence of severe bronchopulmonary dysplasia, delayed onset of enteral feeding and low enteral intake of vitamin A.

Bronchopulmonary Dysplasia↗
PubMed1996

Altered growth and attachment of rabbit crypt colonocytes isolated from different developmental stages.

The rabbit colon was used to establish an in vitro model for examining development-related cellular changes in colonocyte function. Colonic epithelia from newborn, weanling, and adult animals were separated from the muscle and subjected to enzymatic digestion. A mixture of 0.05% Pronase, 0.015% collagenase IV, and 0.023% DTT was determined to be optimal for the isolation of newborn and weanling colonocytes. This solution yielded significantly more cells and of greater viability than a 0.1% Pronase, 0.03% collagenase IV, 0.07% DTT mixture that is optimal for adult colonocytes. The epithelial origin of the colonocytes was confirmed by immunofluorescent staining of cytokeratins. The isolation procedure resulted in a crypt-enriched population and the cell yield/g of mucosa increased with age as did the crypt depth. Colonocyte viability of adults but not of newborns and weanlings, declined from 24 to 72 h. When grown on plastic, the newborn and weanling colonocytes show a approximately 2-fold increase in number, DNA and protein content over 48 h. In contrast, for all three parameters the adult colonocytes revealed only a approximately 10% increase. The colonocytes also showed an age-related decline in attachment to extracellular matrices. Colonocytes showed maximal attachment to Matrigel and collagen IV; newborn and weanling colonocytes show > 80% attachment, whereas adult colonocytes showed only a 45% attachment. The efficacy of attachment to Matrigel compared with that on plastic also differed with age, representing 9.3-, 5.5-, and 4.4-fold increase in adult, weanling, and newborn colonocytes, respectively. Newborn and weanling colonocytes grown on Matrigel for 48 h, showed a significant, 15% increase in cell number, DNA, and protein content compared with those grown on plastic. There was no difference in these parameters when adult colonocytes grown on Matrigel were compared with those grown on plastic. In summary, we have established an in vitro model for studying colonic epithelial cells at different stages of development.

Age Factors↗
PubMed1995

Changes in the concentration of endothelin-1 during development of hypertensive rats.

The concentration of endothelin-1 (ET-1) in the brain regions, heart, and throacic aorta of 1-, 4-, 6- and 8-week-old spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats was determined using radioimmunoassay. ET-1-like immunoreactivity in the brain regions of 1-week-old WKY and SHR rats was lower compared to older (6 and 8 weeks) rats. ET-1 levels in the central nervous system gradually increased with age in both SHR and WKY rats. However, the concentration of ET-1 in 8-week-old rats was lower in the brain regions of SHR compared to WKY rats. The concentration of ET-1 in the thoracic aorta of SHR (224 +/- 43 pg/g tissue) rats was lower than that of WKY (452 +/- 11 pg/g tissue) rats at 1 week of age. However, ET-1 levels gradually increased with age in SHR rats. By 8 weeks of age, levels of ET-1 in SHR (623 +/- 33 pg/g tissue) rats were higher compared to WKY (439 +/- 62 pg/g tissue) rats. In the heart, ET-1 levels were similar in WKY and SHR rats at 4 weeks of age, but at 8 weeks of age ET-1 levels were higher in SHR rats (364 +/- 33 pg/g tissue) compared to WKY rats (260 +/- 31 pg/g tissue). It appears that at 8 weeks of age when hypertension is fully expressed in rats, ET-1 levels are lower in the central nervous system and are higher in the thoracic aorta and heart of SHR compared to WKY rats.

Animals↗
PubMed1995

Somatostatin in preterm infants: postnatal changes and response to stress.

To determine the chronology of postnatal somatostatin (SRIF) changes in preterm infants and the relationship of SRIF levels to respiratory and gastrointestinal complications, we evaluated sequential SRIF levels in 62 preterm infants in the first month of life. Weekly preprandial plasma samples were obtained and analyzed for SRIF using a radioimmunoassay. Additional blood samples were obtained at the time of abdominal events. Somatostatin levels were highest in week 2 and gradually declined in weeks 3 and 4 (mean +/- SD pmol/l, SRIF = 92.3 +/- 30.3 in week 2 vs. 79.8 +/- 33.9 in week 3 and 69.7 +/- 54.4 in week 4, p < 0.03). Birth weight, gestational age and sex were not related to initial SRIF levels. Infants with respiratory distress requiring assisted ventilation had significantly higher week 1 SRIF levels compared to infants without respiratory problems (97.9 +/- 22.7 vs. 74.9 +/- 21 pmol/l, p < 0.02). Twenty-one of the 62 infants had gastrointestinal complications. Somatostatin levels preceding (89.0 +/- 25.9 pmol/ 1), during (91.0 +/- 13.3) and after (79.3 +/- 28.6) the gastrointestinal events were not significantly different, nor were they different from SRIF concentrations of age-matched preterm infants without gastrointestinal complications. The results suggest that in preterm infants, postnatal SRIF changes follow a definite pattern with peak concentrations in week 2. Respiratory distress is associated with a significant increase in SRIF. However, subsequent gastrointestinal events do not lead to an increase in SRIF. This lack of SRIF response in gastrointestinal stress may play a role in the pathogenesis of gut injury in the premature neonate.

Aging↗
PubMed1995

Renal actions of endothelin-1 in newborn piglets: dose-effect relation and the effects of receptor antagonist (BQ-123) and cyclooxygenase inhibitor (indomethacin).

Although the effects of endothelin-1 (ET-1) on intact or perfused adult kidney are well understood, its effects in the fetus and the newborn have not been well studied. We examined the effects of infusions of 25, 50, and 100 ng/kg of ET-1 per minute on mean blood pressure (MBP), cardiac index (CI), renal blood flow (RBF), glomerular filtration rate (GFR), and urine volume (UV) in 7- to 10-day-old piglets (n = 24). In addition, the effects of pretreatment with a receptor antagonist (BQ-123) and with a cyclooxygenase inhibitor (indomethacin) were studied in 12 separate piglets. ET-1 produced a dose- and level-dependent decrease in CI (60%), RBF (50% to 75%), GFR (66% to 80%) and MBP 15% to 17%. These changes returned to 75% to 80% of baseline 60 minutes after discontinuation of ET-1. Low-dose infusion (25 ng/kg) did not result in any changes in systemic or renal hemodynamics. Plasma half-life of ET-1 in piglets was 2.1 +/- 0.4 minutes. Pretreatment with the specific ETA receptor antagonist BQ-123 completely blocked the ET-1-induced systemic and renal hemodynamic changes. Indomethacin blocked the ET-1-induced rise in MBP but failed to block any renal changes. In fact, indomethacin accentuated the changes induced by ET-1, especially the changes in RBF, RVR, and GFR. Studies of receptor binding in the renal cortex and medulla showed that, in the cortex, the Ki value for ET-1 was 6.32 +/- 1.57, and for ET-3 it was 20.05 +/- 4.38 (p < 0.05); in the medulla, the Ki values were similar for both ET-1 and ET-3. These results indicate that in piglets the renal vascular bed is highly sensitive to ET-1, and its effects are predominantly mediated through ETA receptors.

Animals↗
PubMed1993

High-performance liquid chromatographic determination of morphine and its metabolites in plasma using diode-array detection.

An isocratic high-performance liquid chromatographic method has been developed for the determination of morphine, codeine, normorphine, morphine 3-glucuronide and morphine 6-glucuronide in plasma using a diol column and diode-array detection. Samples were extracted using solid-phase extraction with recoveries in excess of 90%. The limit of determination was 1 ng/ml for morphine, codeine and morphine 3-glucuronide, and 10 ng/ml for normorphine and morphine 6-glucuronide. Inter- and intra-day precision were better than 10%.

Chromatography, High Pressure Liquid↗
PubMed1993

Dexamethasone treatment suppresses collagen synthesis in infants with bronchopulmonary dysplasia.

Collagen is an essential component of connective tissue and is present in the pulmonary interstitium. Collagen deposition is known to increase in many acquired chronic diseases, including bronchopulmonary dysplasia (BPD). Urinary excretion of hydroxyproline has been used as a specific index of collagen synthesis. Many studies have demonstrated that dexamethasone therapy is associated with respiratory improvement in infants with BDP but the mechanism of this effect is not well understood. We postulated that in infants with BDP who receive dexamethasone, suppression of collagen synthesis may cause respiratory improvement. Therefore, we studied the effect of dexamethasone on respiratory status and urinary excretion of hydroxyproline in 14 ventilator-dependent infants with BDP. Infants received 0.5 mg/kg/day dexamethasone, tapered by half every 3 days to complete a 12 day course. Eleven of the 14 infants were extubated at a mean +/- SD of 8.7 +/- 4.9 days after starting dexamethasone. Mean urinary hydroxyproline/creatinine ratios at 3, 6, 9, and 12 days of dexamethasone therapy were significantly lower than the mean pretreatment value, but after discontinuation rapidly rose toward baseline values. Decreased urinary excretion of hydroxyproline indicates that dexamethasone suppressed collagen synthesis in these infants. We speculate that suppression of collagen synthesis reduced pulmonary inflammation and fibrosis, resulting in respiratory improvement.

Bronchopulmonary Dysplasia↗
PubMed1993

Cardiopulmonary resuscitation of newborns. Its application to transport medicine.

The outcome of sick infants requiring transport to tertiary care centers is critically dependent on the stabilization of these infants at the hospital of delivery and the quality of care during transport. The American Heart Association/American Academy of Pediatrics guidelines for neonatal resuscitation emphasize a structured, step-wise approach to resuscitation. This article highlights the application of these guidelines to resuscitation of newborns during transport and reviews the experience of a large perinatal network in this area.

Apgar Score↗
PubMed1993

Assessing adherence to standards for neonatal resuscitation taught throughout the perinatal referral area. A quality assurance activity.

The American Heart Association/American Academy of Pediatrics Neonatal Resuscitation Program provides standards for management of newborn infants in birthing areas. Certification and subsequent evaluation of birthing area personnel at perinatal network hospitals should result in better stabilization of infants prior to transport.

American Heart Association↗
PubMed1993

Detection of fetal cocaine exposure by analysis of amniotic fluid.

OBJECTIVE: To determine whether analysis of amniotic fluid (AF) using solid-phase extraction and high-performance liquid chromatography is useful in detecting fetal exposure to cocaine and its metabolites. METHODS: Amniotic fluid and urine samples were obtained from 23 subjects with documented cocaine abuse during pregnancy and five subjects without a history of cocaine abuse. Urine samples were also collected from all newborns. Urine samples were screened using conventional immunoassay techniques and confirmed with thin-layer chromatography. Using a modified solid-phase extraction procedure, we removed cocaine and its metabolites from all AF samples and from the newborn urine samples in which the initial screening was positive. Subsequently, we analyzed the extracts with high-performance liquid chromatography. RESULTS: Cocaine or benzoylecgonine was detected in 74% of AF samples taken from the 23 known cocaine abusers. In these subjects, conventional maternal and neonatal urine toxicology screens were positive in 61 and 35%, respectively. Concentrations in AF ranged from 400 to greater than 5000 ng/mL for benzoylecgonine and from trace to 250 ng/mL for cocaine. Mean benzoylecgonine recovery from AF was significantly greater than from newborn urine (1800 versus 280 ng/mL, respectively; P < .0001). CONCLUSION: Analysis of AF appears to be useful in detecting gestational cocaine exposure.

Amniotic Fluid↗
PubMed1991

Cardiopulmonary resuscitation of apparently stillborn infants: survival and long-term outcome.

To determine the outcome of apparently stillborn infants who received cardiopulmonary resuscitation, we studied the short- and long-term outcome of 93 infants who had an Apgar score of 0 at 1 minute of age and were resuscitated at birth. Sixty-two (66.6%) responded and left the delivery room alive; 26 (42%) of the 62 infants died in the neonatal period and 36 infants were discharged home; of the 36 infants, three subsequently died during infancy. Of the 33 survivors, ten were lost to follow-up after discharge. Developmental assessment of 23 of 33 long-term survivors revealed normal outcome in 14 (61.7%), abnormal results in 6 (26%), and suspect status in 3 (13%). Fifty-eight infants had an Apgar score of 0 at greater than or equal to 10 minutes of age and all except one died; the surviving infant has an abnormal developmental outcome. We conclude that 39% of apparently stillborn infants who were resuscitated survived beyond the neonatal period and that 61% of the 23 survivors who were available for developmental follow-up had normal development at the time of last examination. Survival was unlikely if there was no response after 10 minutes of resuscitation.

Apgar Score↗