Search PubMed⌕ Search

Biomedical subjects

I D Frantz

Publications and source records attributed to I D Frantz.

At least 19 recordsLinked to original sources
PubMed1979

Inhibition of cholesterol synthesis in mammary tissue, lung, and kidney following cholesterol feeding in the lactating rat.

Pregnant rats were randomly allocated to one of 3 experimental dietary groups: Group 1 -- 15.5% butter, 2% cholesterol, 0.78% sodium cholate purified diet; Group 2 -- standard rat diet with the addition of 10% lard and 2% cholesterol, and Group 3 -- standard rat diet. Plasma and milk cholesterol at 10 days postpartum were significantly elevated in dams fed exogenous cholesterol. The rat of incorporation of [1-14C] acetate into digitonin-precipitable sterols of mammary tissue slices from dams in Group 1 and Group 2 was eight-fold and two-fold, respectively, less than controls. Mammary tissue cholesterol was greater in dams fed detary cholesterol. Thus, our data, for the first time, demonstrate that cholesterol synthesis in lactating rat mammary tissue is suppressed following cholesterol feeding. In a second experiment, the rate of incorporation of [1-14C] acetate into digitonin-precipitable sterols in kidney and lung tissue of Group 1 rats was suppressed; however, this response was not as marked as that observed in lactating mammary tissue. The concentration of cholesterol in kidney and lung was greater than controls. These results suggest that extrahepatic inhibition of cholesterol synthesis exists in the rat with a concomitant increase in tissue cholesterol.

Animals↗
PubMed1979

Muscle relaxation in mechanically ventilated infants.

We evaluated the effect of muscle paralysis on gas exchange and incidence of pneumothorax in 35 severely ill infants on mechanical ventilation. Pancuronium (0.1 mg/kg) was given repeatedly until spontaneous respirations ceased in infants with inadequate gas exchange with FIO2 greater than 0.60, or peak inspiratory pressure greater than 30 cm H2O, or who were breathing out of phase with the respirator. Of 27 infants who had an alveolar-arterial oxygen gradient greater than 300 torr before paralysis, AaDO2 improved by greater than 100 torr within one hour of paralysis in only two infants; it worsened in two infants within the same period. By six hours postparalysis, 12 of 27 infants had improved, five of whom had had a worsening AaDO2 before administration of pancuronium. Changes in oxygenation were unrelated to changes in arterial carbon dioxide tension in most infants. Peak transpulmonary pressures after paralysis were lower than during spontaneous breathing, and may explain the low incidence of pneumothorax (3 of 35) during paralysis. Since those who improved could not be distinguished by birth weight, gestational age, or diagnosis, pancuronium might be worthy of trial in a mechanically ventilated infant with severe lung disease who is at risk for pneumothorax.

Carbon Dioxide↗
PubMed1979

The influence of early nutrition on the serum cholesterol of the adult rat.

In two experiments, young rats were preconditioned with dietary cholesterol by: 1) nursing from dams with a high cholesterol milk or, 2) receiving 10 mg cholesterol dissolved in 0.5 ml of corn oil daily from 6 to 30 days of age. When rats preconditioned with dietary cholesterol in early life were fed stock diet supplemented with 10% lard and 0.5% cholesterol ("cholesterol challenge diet") there was no protection against dietary induced hypercholesterolemia in adult life. In a third experiment, two groups of newborn rats were intubated with: 1) a cholesterol free formula, 2) the cholesterol free formula plus 50 mg% cholesterol. A third group of pups suckled normally. After weaning all pups were fed a stock diet supplemented with 10% lard and 0.5% cholesterol for 1 month. There was no difference in the serum cholesterol in either group of artificially reared rats after the "cholesterol challenge" (106 +/- 6 mg/100 ml). Suckled rats, however, had a lower serum cholesterol after the "cholesterol challenge" (75 +/- 2 mg/100 ml). All experiments conducted refute the hypothesis that early exposure to dietary cholesterol protects against dietary induced hypercholesterolemia in adult life. It appears, however, that cholesterol metabolic systems are affected in early life because of the decreased ability of artificially reared rats to handle a "cholesterol challenge." Possible factors include a component of the dam's milk, growth and development, and the psychological and emotional stress of the artificial rearing process.

Aging↗
PubMed1979

Lung volume changes, occlusion pressure and chest wall configuration in human infants.

UNLABELLED: Measurements of respiration were compared in normal, full term and premature infants before and after application of 5 cm H2O continuous negative pressure (CNEG) around the body below the neck. Mean minute ventilation in the full term infants decreased when CNEG was applied, secondary to a decrease in respiratory rate, with tidal volume relatively unchanged. The premature infants showed no consistent ventilatory response to CNEG. There were variable changes in occlusion pressure at increased lung volume. Observation with rib cage and abdomen anterior-posterior (A-P) magnetometers showed that the increase in end-expiratory lung volume was accounted for largely by expansion of the rib cage so that the configuration of the diaphragm and its mechanical advantage were maintained. These results suggest that the diaphragm is the major determinant of mask occlusion pressure in infants. SPECULATION: The effects of increased lung volume on the configuration of the chest wall may relate to the success of continuous distending pressure in the treatment of respiratory disorders in infants, including apnea of prematurity.

Humans↗
PubMed1979

Prolonged expiratory duration with elevated lung volume in newborn infants.

UNLABELLED: End-expiratory lung volume increased 17.5 +/- 5.4 ml (mean +/- SD) in full term infants and 7.7 +/- 2.1 ml in premature infants when 5--7 cm H2O continuous negative pressure (CNEG) was applied around the thorax. In the full term infants, respiratory rate decreased from 52--43 min-1 (P less than 0.001), mean inspiratory duration (ti) was unchanged, and mean duration of expiration (te) increased from 0.62 +/- 0.14 (SE)-0.84 +/- 0.22 sec (P less than 0.001) after application of CNEG. Te of occluded efforts on CNEG was also prolonged (P less than 0.005), although less than te of spontaneous breaths on CNEG (P less than 0.005). Te increased in four of eight premature infants when CNEG was applied. We conclude that phasic vagal feedback regulates Ti and te is controlled by tonic vagal activity. SPECULATION: Premature infants may have an optimum functional residual capacity (FRC) which can be achieved with continuous distending pressure, resulting in regularization of respiration.

Humans↗
PubMed1979

Four electrophoretic methods compared for diagnosis of type III hyperlipoproteinemia.

Blood drawn from 192 probands and 1129 first-degree relatives who were participants in a collaborative family study of hyperlipoproteinemia at nine Lipid Research Clinics was used to prepare aliquots of whole plasma and top (d less than 1.006 g/mL) and bottom (d greater than 1.006 g/mL) ultracentrifugal fractions. Each aliquot was analyzed at a central laboratory by electrophoresis on paper, agarose, and polyacrylamide gel, and by a combined electrophoretic precipitation technique. The electrophoretograms were evaluated for the presence or absence of a "floating-beta" lipoprotein band. All four methods agreed completely for 92.3% of the samples. An additional 2.0% of the samples were in agreement for three electrophoretic methods, but the paper electrophoretic results were not interpretable. Another 1.9% were considered to be "floating-beta" positive by paper electrophoresis but negative by the other three electrophoretic methods.

Chemical Precipitation↗
PubMed1976

Respiratory regulation after elastic loading and CO2 rebreathing in normal term infants.

Studies of airway pressure, tidal volume, respiratory duration, and total breath duration before and after elastic loading airway occlusions were carried out on ten full-term, normal infants on two occassions in the first week of life. Using these noninvasive techniques we infer that static compliance and the Hering-Breuer reflex are unchanged during the first week; that infants may increase sensitivity to chemical drive toward the end of the first week; and that there may be a volume related threshold for vagal inhibition of inspiration in some infants.

Carbon Dioxide↗
PubMed1976

Maturational changes of effective elastance in the first 10 days of life.

The effective elastance of the respiratory system (E'rs) is a measure of its ability to resist a change in tidal volume under conditions of changing elastic loads. E'rs was measured while subjects breathed air and 2% CO2 and 4% CO2 in air in two groups of premature infants of different gestational ages at 1 day 3-4 days, and 7-10 days of age. E'rs was shown to decrease with increasing maturation and was independent of changes in control tidal volume. The decrease of E'rs with increased gestational age could be accounted for by differences in calculated thoracic gas volumes in all but one instance, where E'rs was lower in one group on the 3rd day of life. The activity of the Hering-Breuer reflex, as measured by the degree of slowing of inspiratory time after occlusion at FRC, has been previously reported to be normal to increased in similar infants. This suggests that differences related to size account for most of the maturational changes of E'rs in newborns.

Age Factors↗
PubMed1976

Maturational effects on respiratory responses to carbon dioxide in premature infants.

The respiratory responses of 18 premature infants to breathing steady-state levels of carbon dioxide were quantified by conventional minute ventilation measurements and by measuring the pressure generated after end-expiratory airway occlusions. Since no flow or volume changes occur following airway occlusion, the CO2 response obtained by this measurement is independent of vagal stretch receptor influence and mechanical changes in the lungs. When studied at 3-4 days of postnatal age, a group of 29-32-wk gestation infants had a mean slope of ventilatory response to CO2 of 10.8 +/- 5.6 ml-min-1-kg-1-mmHg-1 as compared to 53.5 +/- 10.8 ml-min-1-kg-1-mmHg-1 (P less than 0.005) for a group of 33-36 wk. When these infants were restudied at 7-10 days of age, the slopes were 21.6+/- 6.6 and 58.4 +/- 10.6 ml-min-1-kg-1-mmHg-1 (P less than 0.01), respectively. The mask pressure response paralleled minute ventilation. We conclude that the increase in ventilatory response to carbon dioxide seen with maturation is not due only to changing mechanical features of the lungs, but to increased sensitivity of respiratory centers to carbon dioxide.

Age Factors↗
PubMed1976

Respiratory response to airway occlusion in infants: sleep state and maturation.

The progressive respiratory response to occlusion of the airway at FRC was measured in a group of full-term and premature human infants. The sleep state of the full-term infants was shown to affect the response primarily through variations in the phase of thoracic and abdominal movements. The weakest responses were seen in those infants who demonstrated parodoxical respiration prior to occlusion. Most infants developed paradoxical respiratory movements after occlusion, but this did not affect the strength of the load-compensatory response. An increase in response related to both gestational and postnatal age was observed. This increase could not be accounted for by variations in the amount of paradoxical and in-phase respiration and thus may represent an increase in the sensitivity of infants to chemical stimuli with maturation.

Aging↗
PubMed1975

The progressive response of the newborn infant to added respiratory loads.

The responses of 10 normal full-term infants to 10-sec airway occlusions at functional residual capacity were studied. The responses were quantified by measuring the pressure generated on successive inspiratory efforts following occlusions in room air and 100% oxygen. The response after oxygen breathing was 30-40% less than after air breathing, indicating that hypoxia accounted for part of the response. There was an increase in the response in air from the first to the fourth day of life. Endtidal carbon dioxide tension was shown to increase during the occlusion, but the response remaining after hypoxia was eliminated may not have been due entirely to hypercapnea. We conclude that the compensatory response of the infant to added respiratory loads is in part due to hypoxia, and that the hypoxic response increases over the first week of life.

Airway Obstruction↗
PubMed1975

Necrotizing enterocolitis.

The clinical course of 54 patients with necrotizing enterocolitis has been compared to a matched group of 98 control patients. On the day of life that NEC occurred, all 54 NEC patients and 63% of controls were receiving standard formula feedings, both at 80/cal/kg/day. Stool cultures at the time revealed a significantly increased frequency of Klebsiella in NEC as compared to control patients. Our data suggest that the combined presence of certain intestinal bacteria and enteric feedings, perhaps requiring a background of mucosal ischemia, may be of etiologic significance in the development of NEC and its radiologic hallmark, pneumatosis intestinalis.

Birth Weight↗