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Biomedical subjects

R D Jansen

Publications and source records attributed to R D Jansen.

30 records · Page 2Linked to original sources
PubMed1984

Effects of asphyxia at birth on postnatal glucose regulation in the rat.

We have characterized the effect of a period of asphyxia at birth, followed by recovery, upon newborn rats. Asphyxiated pups were subjected to 3 to 5% (v/v) inspired oxygen during the first 20 min of life and then maintained in room air for 6 h. Control pups were maintained in room air throughout the 6-h period. Hypoxia produced severe asphyxia as reflected by a pH of 6.76 +/- 0.05, PaCO2 of 87 +/- 3 mm Hg and PaO2 of 15.4 +/- 4 mm Hg, and by a greatly increased blood lactate/pyruvate ratio. Plasma catecholamine concentrations in asphyxiated pups were elevated (epinephrine 13,866 +/- 250 pg/ml, norepinephrine 9611 +/- 1813 pg/ml) compared to control animals (epinephrine 973 +/- 234 pg/ml, norepinephrine 774 +/- 133 pg/ml) at 20 min. Asphyxia initially increased plasma glucose concentration, and then with recovery it fell below controls. Hepatic glycogen stores did not differ between asphyxiated and control pups. Plasma insulin concentrations remained elevated during asphyxia and the usual neonatal surge of plasma glucagon was significantly delayed. Neonatal asphyxia increases catecholamines, causes lactic acidemia, and alters insulin and glucagon levels. The interactions between these variables alters the normal pattern of glucose availability during the neonatal period.

Animals↗
PubMed1983

Developmental outcome of very low birth weight infants requiring a ventriculo-peritoneal shunt.

All infants of less than 1,500 g birth weight who required a ventriculo-peritoneal shunt were followed for developmental problems over the 1st year of life. There were 19 infants; 2 died within the 1st postoperative week. At 1 year of age corrected for prematurity the mean Bayley Mental Developmental Index was 62 +/- 23.0, and the mean Psychomotor Developmental Index was 61 +/- 19. Only 2 infants attained scores greater than 85 on both scales, while an additional 2 infants attained a score of greater than 85 on one scale. It is concluded that ventriculo-peritoneal shunting procedures performed after progressive ventricular enlargement has taken place are not likely to result in normal development of the infant less than 1,500 g birth weight.

Cerebrospinal Fluid Shunts↗
PubMed1982

The energy content of infant formulas.

The reported energy content of infant formulas will vary, depending upon the method used to calculate or measure the caloric value. Manufacturers' specifications regarding the energy content of milk formulas reflects the 'metabolizable' energy. i.e., the amount of energy which is digested and absorbed by the infant. However, estimates of absorptive efficiency are based primarily upon studies in young adult subjects fed mixed diets and therefore may not be generally applicable to all neonates. The actual caloric content of formulas may be determined accurately by bomb calorimetry which is not influenced by the relative metabolic efficiency of the infant who may utilize the formula. Therefore, it may be preferable to express the caloric value of milk base formulas in terms of absolute combustible energy.

Calorimetry↗
PubMed1982

Attentional alterations of slant-specific interference between line segments in eccentric vision.

Slant-specific interference between line segments in eccentric vision was altered by attentional methods in hypnotically susceptible observers. These methods included negative and positive posthypnotic hallucination of the inducing elements of the array, and nonhypnotic instruction to actively ignore the elements. Contributions to the experimental effects apparently derived in part from intrinsic inhibitory or facilitatory skill in the individual observer, sharpened by hypnotic training in hallucinations. Control observers with low and with high hypnotic susceptibility were not able to alter significantly the interference effect when attempting to simulate the hallucination conditions. The results seemingly link these attentional alterations to an early cortical stage of visual processing.

Adolescent↗
PubMed1982

Evaluation of a system for continuous neonatal blood pressure monitoring.

The purpose of this study was to determine the effects of varying infusion rates as well as different catheter sizes and types on the mean arterial pressure as measured by a system in which the pressure transducer is connected in series to the line of fluids being administered through the catheter. The results of this study show that, under most circumstances, errors in mean blood pressure measured by this system are minimal and clinically insignificant.

Blood Pressure Determination↗
PubMed1979

Nasogastric hyperalimentation through a polyethylene catheter: an alternative to central venous hyperalimentation.

We performed nasogastric hyperalimentation with polyethylene catheters and appropriate feeding solutions in 12 cachectic patients who had been referred as candidates for central venous hyperalimentation. Most patients had primary gastrointestinal disease. The duration of hyperalimentation averaged 31 days. Seven patients obtained rapid weight gain (average 0.3 kg/day) with the nasogastric hyperalimentation alone. An additional two were successfully repleted with the addition of parenteral fluids via peripheral veins. In the nine repleted patients, serum albumin rose by average 19%, 24-hr urine creatinine by average 21%, and triceps skinfold by average 46%. The nature of the weight gain in the nine successful cases was analyzed by the metabolic balance study technique. Average composition of the increment in weight was: 50% protoplasm, 48% extracellular fluid, 19% adipose tissue, and less than 1% bone. We conclude that nasogastric hyperalimentation can replace central venous hyperalimentation in a substantial proportion of patients now receiving the latter type of treatment.

Adult↗
PubMed1979

Tyramine kinetics and metabolism in cirrhosis.

Hypertyraminemia is common in hepatic cirrhosis and correlates in severity with encephalopathy. The mechanism of cirrhotic hypertyraminemia has not been established. The alternative possibilities are increased production from tyrosine and impaired degradation by monoamine oxidase. This investigation determined the pharmacokinetics of tyramine after an intravenous bolus injections of [3H]-tyramine (180--200 muCi 12 Ci/mmol sp act) in 13 cirrhotics and 9 controls. In normals, [3H]tyramine levels initially declined rapidly (alpha-phase) followed by a slower decline (beta-phase) with an average t 1/2 of 20.8 min. Average normal metabolic clearance rate and production rate were 13.2 liters/min and 15.4 microgram/min, respectively. In cirrhotic patients, the plasma disappearance curve for [3H]tyramine was qualitatively similar to that of the control subjects with no apparent different in beta-t 1/2 (17.2 min). The hypertyraminemia of cirrhosis resulted primarily from overproduction of tyramine, as the production rate (32.0 microgram/min) in these patients was significantly greater (P less than 0.05) than in controls, whereas the metabolic clearance rate remained normal (average 12.2 liters/min). A difference in ratio of tyramine metabolic products was noted as well. Cirrhotics had a high ratio of plasma 4-hydroxyphenylethanol:4-hydroxyphenylacetic acid (60:40 vs. 30:70) as compared with normals. Although the tyramine clearance rates are similar in normals and cirrhotics, different mechanisms may be responsible for catabolism.

Adult↗