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Biomedical subjects

V Chernick

Publications and source records attributed to V Chernick.

At least 91 records · Page 5Linked to original sources
PubMed1980

Respiratory response to somatic stimulation in fetal lambs during sleep and wakefulness.

1. The respiratory response to electrical stimulation of the nose, tail, gum and fibular nerve (nonspecific somatic stimulation) was tested in chronically instrumented fetal lambs during sleep and wakefulness. 2. The respiratory response to somatic stimulation was greatest during REM sleep, lowest during NREM sleep, and intermediate during the awake state (AW). 3. Respiratory responses could follow electrical somatic stimulation up to 2 Hz in any sleep state without changing sleep state. 4. The fetal breathing (FB) response to repetitive stimulation depended on the initial sleep state and whether or not the sleep state was affected by the stimulation. Five patterns of response were seen: a) NREM leads to NREM (initial sleep state and sleep state at end of stimulation)--FB was initiated and did not continue beyond the duration of the stimulation. b) NREM leads to REM sleep--FB was initiated and continued beyond the time of stimulation. c) REM leads to REM sleep--spontaneous FB was enhanced and continued beyond the time of stimulation. d) REM leads to NREM sleep--spontaneous FB was enhanced but did not continue beyond the time of stimulation. e) NREM, REM sleep, Awake leads to Awake--FB was initiated or enhanced and continued beyond the time of stimulation until the onset of NREM sleep.

Animals↗
PubMed1980

Sleep, wakefulness and the monosynaptic reflex in fetal and newborn lambs.

1. Electrocorticogram (ECoG), electromyogram (EMG) of the lateral rectus and antigravity muscles (neck and masseter) and breathing activity (FB) were monitored in chronically prepared fetal sheep of 125-140 days gestation and in newborn lambs up to 11 days postnatal age. 2. Awake state (AW), non-rapid eye movement sleep (NREM) and rapid eye movement sleep (REM) were defined using standard criteria for ECoG, eye movements and postural muscle tone. 3. The percentage of time the fetuses spent in each state was: NREM sleep 53%, REM sleep 41.4%, and AW 5.6%. 4. Spontaneous intrauterine breathing activity occurred only during REM sleep, but 35% of REM sleep was not associated with FB. 5. Gasps (isolated deep inspirations) appeared occasionally throughout the recording and were not related to any specific sleep state or wakefulness. 6. In the fetus, the monosynaptic reflex (MSR) induced by direct electrical stimulation of the fibular nerve was enhanced by about 75% during REM sleep compared to NREM and AW. In the newborn lamb the adult pattern of suppression of MSR during REM sleep was not seen until several days after birth.

Animals↗
PubMed1980

Endogenous opiates and chemical control of breathing in humans.

Endogenous opiates are found in large concentrations in the brainstem of vertebrate animals, suggesting that they play a possible role in the central control of breathing. To examine this possible role in human ventilatory control we evaluated the effect of nalozone, a specific opiate antagonist, on the ventilatory and mouth occlusion pressure (P0.1) responses to hypercapnia and hypoxia in 6 normal men 22 to 48 yr of age. In a random double-blind crossover study, each subject received both an intravenous infusion of 50 mg of naloxone and a placebo infusion of normal saline. Ventilatory responses were measured before and 5 min after each infusion. Ventilatory responses to hypercapnia and hypoxia were more marked after both the saline and naloxone infusions, but there was no significant difference in the responses between the 2 infusions. Similarly there was no significant difference in respiratory timing or mean inspiratory flow between the 2 infusions at an arterial oxygen saturation (SaO2) > 95%. We concluded that endogenous opiates have no major influence on the chemical control of breathing in normal humans.

Adult↗
PubMed1980

Naloxone decreases the duration of primary apnea with neonatal asphyxia.

Naloxone, a specific opiate antagonist with no agonist properties, in doses of 0.4 and 4.0 mg/kg was found to markedly reduce the duration of primary apnea in asphyxiated newborn rabbits. There was no effect on the duration of the hyperpneic phase (time to primary apnea) or on survival time (time to last gasp). It is suggested that endogenous opiate-like peptides are released during asphyxia and are the major factor in the suppression of medullary inspiratory neuronal discharge during primary apnea.

Animals↗
PubMed1977

EEG frequency spectrum characteristics of sleep states in infants of alcoholic mothers.

Infants of alcoholic mothers showed prominent EEG hypersynchrony in all three stages of sleep: in quiet sleep, indeterminate sleep and active-REM sleep. Spectral analysis of the EEG using fast Fourier transform revealed significant increase in power in most frequency bands in all three stages of sleep in infants born to alcoholic mothers when compared with normal healthy infants matched for gestational age. In quiet sleep "alcoholic" infants differed from healthy babies by significantly higher power in a wide range of frequency bands (1.5--17.5 Hz) with an average 143% increase of the integrated EEG (1.5--25 Hz). In indeterminate sleep "alcoholic" infants showed significantly higher power in all analyzed frequency bands (0.1--25 Hz) with an average 196% increase of the integrated EEG (1.5--25 Hz). In active-REM sleep infants of alcoholic mothers showed significantly higher power in the frequency range from 0.1 to 17.5 Hz in comparison with healthy controls. The average increase of the integrated EEG (1.5--25 Hz) was 200%. All healthy term infants showed significantly higher power in most frequency bands during quiet sleep in comparison with active-REM sleep. In infants born to alcoholic mothers this quiet sleep--REM sleep frequency spectrum difference in the majority of cases was nonsignificant mainly due to high values of the EEG power during REM sleep. It is unlikely that the EEG hypersynchrony in infants of alcoholic mothers represents one of the symptoms of the neonatal alcohol-withdrawal syndrome since hypersynchrony has been detected as long as 6 weeks after birth. During this time any withdrawal symptoms would have been dissipated.

Age Factors↗
PubMed1976

Enhanced fetal erythrocyte carbonic anhydrase activity by hydrocortisone.

The present experiments were undertaken to study the effect of exogenous corticosteroids on carbonic anhydrase (CA) activity in fetal erythrocytes. Rabbit fetuses from 24 days of gestation to term (31 days) were injected intraperitoneally with either 0.2 ml of 0.9% saline or 2.5 mg hydrocortisone succinate. Nonoperated, noninjected animals served as controls. Carbonic anhydrase activity measured at 24 hr after injection was increased in the saline-injected group at all ages studies when compared with the noninjected fetuses. A marked increase (2- to 7-fold) in enzyme activity was demonstrated after steroid injection at 24 but not 48 hr after treatment. An increase in CA activity was also demonstrated after incubating fetal erythrocytes for 2, 4, and 8 hr in the presence of hydrocortisone succinate. It is suggested that low CA activity in infants with hyaline membrane disease (HMD) may reflect lack of enhancement by steroid.

Animals↗