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Biomedical subjects

V Chernick

Publications and source records attributed to V Chernick.

At least 73 records · Page 4Linked to original sources
PubMed1984

Human pancreatic growth hormone releasing factor (hpGRF-1-40) stimulates GH release in the ovine fetus.

The effects of growth hormone-releasing factor, hpGRF (1-40), on plasma GH levels were studied in chronically catheterized ovine fetuses between 71 to 134 days of gestation. The basal ovine (o) GH levels in the fetus ranged between 41 - 144 ng/ml, while values in the ewe were often less than 6 ng/ml. hpGRF (1-40), 5 micrograms/kg infused into a fetal vein, markedly stimulated GH release in all nine fetuses. The maximum increase above pretreatment levels (net increases) ranged from 65 ng/ml to 498 ng/ml, with a mean net increase of 229 ng/ml. The responses of oGH in fetuses at younger gestational age appeared to be greater than in older fetuses. Mean plasma oPRL did not change after hpGRF infusion. These results indicate that somatotrophs in fetal sheep in mid- and late gestation have receptors for GRF, and GH secretion may be modulated by GRF at this stage of gestation.

Animals↗
PubMed1984

Prolonged effects of maternal alcohol ingestion on the neonatal electroencephalogram.

Newborn infants of mothers who drink heavily (greater than 2 oz alcohol per day) during pregnancy have been shown to have hypersynchrony of the EEG. The possibility that hypersynchrony is related to acute alcohol withdrawal was tested. Eleven preterm infants of mothers who drank heavily ("alcoholic") were studied at a postnatal age of 4 to 6 weeks using power spectral analysis of EEG signals. This group was compared with a control group with similar racial and socioeconomic status. In addition, a group of ten "healthy" preterm infants was compared with a carefully matched control group. Total power of the EEG during quiet, indeterminate and rapid eye movement (REM) sleep was 162%, 183%, and 188%, respectively, in the infants whose mothers were alcoholic when compared with their control infants or with the healthy preterm infants and their control infants. It is concluded that ingestion of alcohol during pregnancy may result in potentially serious prolonged effects on brain function of the offspring, even in the absence of dysmorphology.

Adolescent↗
PubMed1983

Effects of maternal alcohol intake and smoking on neonatal electroencephalogram and anthropometric measurements.

Anthropometric data and computerized electroencaphalogram analysis during quiet, indeterminate, and active sleep were obtained from infants of mothers of four groups: (1) heavy drinking mothers (greater than 2 ounces of alcohol per day); (2) nondrinking mothers; (3) smoking, nondrinking mothers; (4) nonsmoking, nondrinking mothers. Infants in groups 1 and 2 were matched as closely as possible for postconceptional age, sex, race, and socioeconomic status. Infants in groups 3 and 4 were matched similarly. Infants of alcoholic mothers had a significantly lower birth weight, length, and head circumference than those from the matched control group. Infants of smoking mothers had lower birth weights and lengths than infants of nonsmoking mothers, but head circumference was identical. Hypersynchrony of the electroencephalogram was seen only in "alcoholic" infants, and power spectral density analysis revealed that the average integrated power was significantly increased in quiet, active, and indeterminate sleep. The greatest increase in electroencephalogram power (212%) was seen in active sleep, and this analysis clearly separated 15 of 17 alcohol-exposed infants from the control infants. These data suggest that alcohol has a specific toxic effect on the fetal brain that is not linked with smoking habits. The neonatal electroencephalogram is affected even in the absence of dysmorphology and thus may be the most sensitive indicator of fetal alcohol toxicity.

Adolescent↗
PubMed1983

Drug-induced changes in fetal breathing activity and sleep state.

Drugs reported to stimulate fetal breathing (FB) were injected into a femoral vein of near-term fetal lambs during rapid eye movement (REM) and non-REM (NREM) sleep. The primary response to NaCN, 0.25-0.5 mg, a dose which did not flatten the electrocorticogram, was a brief burst of gasping in any sleep state. When injected during REM sleep, NaCN caused the cessation of spontaneous FB and the onset of gasping. Stimulation of FB was observed infrequently. Caffeine (10 mg) and doxapram (3 mg) frequently caused an immediate change in sleep state or arousal. The incidence of FB increased concomitantly with a change to REM sleep or wakefulness (W), but FB still ceased with the onset of NREM sleep. When administered during an episode of spontaneous FB during REM sleep, both caffeine and doxapram caused stimulation of the frequency and depth of breathing. Pilocarpine (4 mg) caused arousal and gasping followed by prolonged vigorous breathing that was dependent on intact carotid sinus nerves. Indomethacin (120 mg over several hours) did not affect sleep states but induced FB in both NREM and REM sleep. In summary, in the fetus the primary effect of NaCN is to suppress spontaneous FB and induce gasping and the effects of pilocarpine, caffeine, and doxapram are intimately related to sleep states or arousal. Indomethacin causes the conversion from episodic fetal to continuous postnatal-type breathing. These data indicate the importance of assessing fetal state of consciousness in interpreting the respiratory response to drugs.

Animals↗
PubMed1983

Chronic extracellular recording of fetal medullary neuronal activity.

A technique for chronic extracellular recording of neuronal activity in the medullary region of fetal sheep during different sleep states is described. Of 51 recorded neurones, 54% were associated with respiration, blood pressure changes, or muscle electromyograms, and 46% were nonspecific. During apnea (nonrapid-eye-movement sleep) both inspiratory and expiratory neurons had random intermittent activity. Thus apnea is not associated with tonic expiratory neuronal activity.

Animals↗
PubMed1983

Bacterial tracheitis--an old disease rediscovered.

During a 3-year period, seven children with bacterial tracheitis were admitted to the intensive care unit of the Winnipeg Children's Hospital. The illness was characterized by fever, toxicity, and stridor. Respiratory difficulty was secondary to copious thick purulent tracheal secretions. In the majority of patients the illness was caused by Staphylococcus aureus, and the rest had Hemophilus influenzae infection. Viral studies in five patients were negative. Most patients required endotracheal intubation and frequent tracheal toilet to prevent serious airway obstruction. In our ICU, bacterial tracheitis accounted for about 14 per cent of admissions with infectious upper airway obstructive illness, while epiglottis and croup accounted for 55 per cent and 31 per cent, respectively. Only 5 per cent of children with croup admitted to the hospital were admitted to the ICU. Bacterial tracheitis has reappeared, at least in North America, as an important and serious cause of obstructive upper airway disease in children and must be recognized early in order to prevent catastrophic airway obstruction.

Airway Obstruction↗
PubMed1982

Naloxone reverses neonatal depression caused by fetal asphyxia.

Pregnant near-term rabbits were given an intravenous dose of saline or the opiate antagonist naloxone and then asphyxiated. The fetuses were delivered by cesarean section and evaluated for respiration, color, muscle tone, response to stimulation, and general activity at 1, 3, 5, 10, 15, and 30 minutes of age. The naloxone-treated pups had significantly better scores during the first 15 minutes after birth than the saline-treated pups. Naloxone did not adversely affect the scores of nonasphyxiated pups. These data suggest that endogenous opiates worsen the neonatal depression caused by intrauterine asphyxia and that this effect can be reversed by naloxone.

Animals↗
PubMed1982

Influence of sleep state on the response to hypercapnia in fetal lambs.

The effect of sleep state on the respiratory response to hypercapnia was studied in 14 chronic fetal sheep, 125-140 days gestation. Fetal PaCO2 was raised by 11 to 34 Torr by gradually increasing the maternal FICO2 to 0.09. Fetal sleep state was monitored. Fetal breathing (FB) was analysed in terms of frequency (f), tracheal pressure (TP) and ventilation equivalent (VEq) = sigma TP /min. In 16 out of 17 experiments on apneic fetuses in NREM sleep, the fetuses switched to REM sleep and in 14 instances began to breathe within 2 1/2 min thereafter. The PaCO2 at which apneic fetuses started breathing was 54.8 +/- 8.4 Torr (mean +/- SD). In 4 out of 10 trials on breathing fetuses in REM sleep the fetuses switched to NREM sleep and stopped breathing before removal of the CO2 stimulus. During REM sleep hypercapnia stimulated FB by an increase in TP and by a reduction in the number and duration of apneic pauses. It is concluded that in the fetal lamb CO2 stimulates breathing only during REM sleep and that this stimulus is superimposed on the basic mechanism that stimulated spontaneous FB during this sleep state.

Animals↗
PubMed1982

Cranial blood volume changes during mechanical ventilation and spontaneous breathing in newborn infants.

We derived a noninvasive method to compare changes in cranial blood volume during mechanical ventilation with changes occurring during spontaneous breathing in newborn infants. In ten infants receiving mechanical ventilation, cranial blood volume increased during inspiration by a mean of 8.3%. We found a consistent relationship between clinical estimation of lung compliance and the amount of cranial volume expansion. During spontaneous breathing in ten infants cranial blood volume decreased during inspiration by a mean of 5.8%. The findings indicate the need for careful monitoring during periods of rapid changes in lung compliance.

Blood Volume↗
PubMed1982

Adenovirus bronchiolitis in Manitoba: epidemiologic, clinical, and radiologic features.

We reviewed our experience with 41 children hospitalized from 1974 to 1978 for adenovirus (ADV) bronchiolitis. Thirty-two patients (78 percent) were native Indians between four and 12 months old. In 18 of the 41 patients (43.9 percent) acute complications developed. The five fatal cases (12.2 percent) were confined to native children. The initial chest roentgenograms showed lobar consolidation in 35 patients (85.4 percent). Atelectasis developed in five (12.2 percent) during hospitalization. Sixteen of 25 patients (64 percent) with adequate radiologic follow-up examination had subsequent pneumonias or showed residual chronic changes. The reasons for the predilection of ADV bronchiolitis in native Indian children and the precise effect on subsequent airway function in survivors are unknown and require further study. We emphasize the importance of ADV as a cause of bronchiolitis in native Indian children. Furthermore, this report focuses attention on the contribution of this disease to the spectrum of chronic pulmonary disorders in the pediatric group.

Adenoviridae Infections↗
PubMed1981

Regular fetal breathing induced by pilocarpine infusion in the near-term fetal lamb.

We report that pilocarpine, a cholinergic drug, stimulated regular sustained breathing movements in 10 near-term fetal lambs with chronically implanted catheters in the carotid artery, jugular vein, and trachea. With increasing doses of pilocarpine (0.1-5.9 mg), there was an enhanced respiratory response as measured by the duration of continuous breathing movements (14 +/- 12 min, increasing to 82 +/- 50 min; mean +/- SD), and the mean tracheal pressure per breath at end inspiration during the first 2 min after drug infusion (18 +/- 5, increasing to 38 +/- 12 mmHg). The mean pressure per breath during the control periods was 8 +/- 3 mmHg. There was no significant change in the breath frequency with increasing drug dose. A similar breathing response was not seen with epinephrine, suggesting that pilocarpine does not act by stimulating release of endogenous catecholamines. There was no fetal breathing response to pilocarpine infusion in atropine-pretreated fetal lambs, suggesting tha pilocarpine acts through a muscarinic mechanism. In eight acute experiments on exteriorized fetal lambs, we measured responses to pilocarpine before and after carotid sinus nerve ligation. The response to pilocarpine was abolished by sinus nerve section, suggesting possible mechanisms whereby pilocarpine may stimulate fetal breathing: the drug may increase peripheral chemoreceptor output, may sensitized the central respiratory centers to peripheral chemoreceptor input, of both.

Animals↗
PubMed1981

Effect of carotid chemoreceptor denervation on breathing in utero and after birth.

The influence of the carotid bodies on fetal breathing activity in utero and on the establishment of postnatal breathing was studied. The electrocorticogram, the electromyogram of the lateral rectus and postural muscles, and tracheal and arterial pressures were monitored on chronically prepared intact and carotid sinus-denervated fetal lambs. The denervated fetuses required a longer time for recovery from the operation, but thereafter the sleeping and breathing behavior was similar to that of the control group. Four of the carotid sinus-denervated fetuses were allowed to be delivered spontaneously, and all established regular postnatal respiration despite conclusive evidence of nonfunctional carotid bodies. These experiments indicate that the fetal carotid chemoreceptors are not essential for the spontaneous intrauterine breathing activity during rapid-eye-movement sleep nor for the establishment of effective breathing at birth.

Animals↗
PubMed1981

Effect of feeding on the chemical control of breathing in the newborn infant.

To examine the influence of feeding on the chemical control of breathing in neonates, we studied the ventilatory response to 3% CO2 in air in nine bottle fed (BOT) and eight breast fed (BR) term infants during feeding while the infants were alert. Control responses were obtained either before or after feeding, VE, respiratory frequency, tidal volume, inspiratory time, expiratory time, and sum of inspiratory and expiratory time, VT/Ti/Ttot, PACO2 and slope (S) of CO2 response (liter/min/kg/mmHg) were determined. During 3% CO2 while resting BR had a lower VE, VT, VT/Ti than BOT and S in BR was 40% of BOT (P less than 0.05). During feeding and CO2 when compared to resting and CO2 there was no difference in either BR or BOT in VT/Ti but Ti/Ttot decreased in both groups. During feeding, S in BOT was reduced from 0.049 +/- 0.012 (mean +/- S.E.) to 0.013 +/- 0.002 (74% reduction) and in BR from 0.020 +/- 0.002 to 0.009 +/- 0.002 (55%). Thus, behavioral activity (either BR or BOT) markedly depresses the ventilatory response to chemical stimuli (CO2). This modification is primarily related to changes in "effective" respiratory timing (Ti/Ttot) rather than mean inspiratory flow (VT/Vi).

Bottle Feeding↗