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Biomedical subjects

R Larsen

Publications and source records attributed to R Larsen.

At least 163 records · Page 9Linked to original sources
PubMed1983

Inhibition of liver surface membrane Na+, K+-adenosine triphosphatase, Mg+2-adenosine triphosphatase and 5'-nucleotidase activities by protoporphyrin. Observations in vitro and in the perfused rat liver.

To clarify the pathogenesis of protoporphyrin-induced cholestasis, liver surface membrane enzyme activities were determined after (a) isolated rat liver perfusion with protoporphyrin administered by bolus (1.0 mumol) or bolus plus constant infusion (1.0 mumol + 0.05 mumol/min) and (b) combination of liver surface membrane with protoporphyrin (0.9-53.4 nmol/ml) in vitro. The perfusion studies showed that protoporphyrin significantly inhibited Na+, K+- and Mg+2-adenosine triphosphatase activities. In vitro, these adenosine triphosphatase activities and the 5'-nucleotidase activity were inhibited linearly by protoporphyrin up to a concentration of approximately 18 mumol/ml; thereafter, enzyme activity was maintained. Greater inhibition of the adenosine triphosphatase activities occurred with protoporphyrin than was reported for chlorpromazine at similar molar concentrations. This effect was independent of the quantity of membrane protein analyzed and was not reversible with a 50:1 dilution. The inhibitory effect of protoporphyrin on surface membrane enzyme activities was also nonselective. Although the hepatotoxic effects of protoporphyrin may be more generalized, the present data underscore protoporphyrin's toxic interaction with liver surface membranes.

5'-Nucleotidase↗
PubMed1982

Myocardial blood flow and oxygen consumption during high-dose fentanyl anesthesia in patients with coronary artery disease.

The effects of high-dose fentanyl-oxygen anesthesia (100 micrograms/kg) on myocardial blood flow (argon washin), myocardial oxygen consumption, myocardial lactate balance, and cardiovascular dynamics were studied in nine patients undergoing three-vessel coronary artery bypass operations. All patients had been on maintenance doses of a beta-receptor blocker (pindolol). Except for pindolol all medication had been discontinued 48 hours prior to the study. Measurements were performed in the awake state, after 10 micrograms/kg fentanyl, after 100 micrograms/kg fentanyl, and during sternotomy. Moderate doses of fentanyl (10 micrograms/kg) produced minimal changes in myocardial blood flow, myocardial oxygen consumption, and cardiovascular dynamics; myocardial oxygen balance as well maintained. Large doses of fentanyl (100 micrograms/kg) produced a 16 per cent decrease in mean aortic pressure, cardiac index did not change significantly, while stroke volume index decreased by 23 per cent. Myocardial oxygen consumption decreased by 14 per cent and myocardial blood flow by 10 per cent. Myocardial lactate production was observed in five patients, indicating myocardial ischemia. During sternotomy arterial pressure and heart rate increased 8 per cent and 29 per cent, respectively, resulting in an increase in myocardial work, as reflected by a 38 per cent increase in myocardial oxygen consumption and by a 54 per cent increase in myocardial blood flow. Myocardial lactate production was observed in seven of nine patients. Our data demonstrate that in patients on maintenance doses of beta-receptor blockers, large doses of fentanyl as the sole "anesthetic" produce incomplete anesthesia and fail to protect the myocardium from ischemia due to noxious stimuli during coronary artery surgery.

Adult↗
PubMed1982

Avoiding psychic adverse effects during induction of neurolept anaesthesia with levomepromazine. A double-blind study of levomepromazine and droperidol.

Levomepromazine 0.1 mg/kg or droperidol 0.15 mg/kg for induction of neurolept anaesthesia were compared in a double-blind prospective study of 60 patients undergoing upper abdominal surgery. On the morning after surgery, eight of 30 patients (26.7%) who received droperidol remembered having had unpleasant anxiety, or nightmarish or panicky experiences during induction of anaesthesia, whereas only one of 30 patients (3.3%) receiving levomepromazine experienced such unpleasant adverse effects (P less than 0.01). During anaesthesia, the patients induced with levomepromazine needed somewhat less fentanyl, had somewhat less pain intensity, during the first 3 h after surgery, and they required the first postoperative dose of morphine 1.5 h later than the patients receiving droperidol (P less than 0.02). There was no difference in the number of patients receiving naloxone at the end of anaesthesia in the two groups. However, 21 of 30 patients (70%) in the levomepromazine group and only seven of 30 patients (23.3%) in the droperidol group were given physostigmine for arousal at the end of anaesthesia (P less than 0.01). There was no difference between the two groups in the occurrence of postoperative nausea, restlessness, hallucinations, or sedation in the recovery ward. This study shows that levomepromazine is superior to droperidol for induction of neurolept anaesthesia because it gives less psychic adverse effects, more analgesia, and a deeper sedation, which is easily reversed with physostigmine at the end of anaesthesia.

Abdomen↗
PubMed1982

Nitroprusside-hypotension: cerebral blood flow and cerebral oxygen consumption in neurosurgical patients.

The effects of nitroprusside-induced hypotension on cerebral blood flow and cerebral oxygen consumption were investigated in nine patients scheduled for cerebral arterial aneurysm surgery. Anesthesia was maintained with nitrous oxide/oxygen and fentanyl; muscle relaxation was achieved with pancuronium; PaCO2 was maintained at 4.79-5.32 kPa. Mean arterial pressure was reduced to 50 mmHg by nitroprusside infusion after opening of the dura. Measurements were recorded and blood samples were taken 15 min before induction of hypotension, during stable hypotension and 15 min after termination of nitroprusside infusion. Measurements included: cerebral blood flow, using the argon-washin technique, cardiac output (thermodilution), mean arterial pressure and heart rate. Cerebral blood flow averaged 56 +/- 6 min . 100 g before hypotension. Nitroprusside produced hypotension but did not significantly alter cerebral blood flow (61 +/- 7 ml/min . 100 g). Cerebral blood flow remained virtually at preinfusion values upon cessation of infusion (53 +/- 6 ml/min . 100 g). Cerebral oxygen uptake averaged 3 +/- 0.2 ml/min . 100 g before hypotension and did not change significantly during hypotension (3.3 +/- 0.3 ml/min . 100 g) and after termination of hypotension (2.7 +/- -0.3 ml/min . 100 g). In two patients nitroprusside produced a 17 and 20% increase, respectively, in cerebral blood flow with no change in cerebral oxygen consumption, together with a marked increase in cardiac output and heart rate.

Adolescent↗
PubMed1982

[Morphine-"anesthesia"--coronary blood flow and oxygen consumption in patients with coronary artery disease].

The effects of large dose morphine-oxygen "anaesthesia" (6 mk/kg) on myocardial blood flow (argon wash-in), myocardial oxygen consumption, myocardial lactate balance and cardiovascular dynamics were studied in 8 patients on maintenance doses of beta-receptor antagonists undergoing two or three vessel coronary artery bypass operations. Measurements were performed in the awake state, 10 min after morphine infusion without surgical stimulation, during sternotomy and 3-4 h after the operation in the intensive care unit at normothermia. Large doses of morphine produced a 13% reduction in coronary blood flow and myocardial oxygen consumption. Mean arterial pressure was significantly reduced with two patients requiring administration of a vasopressor. During sternotomy arterial pressure and heart rate markedly increased, resulting in an increase in myocardial work as reflected by a 40% increase in myocardial oxygen consumption and coronary blood flow. 7 patients required vasodilator therapy. Myocardial lactate production was observed in 1 patient. During recovery blood pressure was reduced while heart rate was increased. Myocardial oxygen consumption was reduced by 18% while coronary blood flow had reached preinfusion levels indicating luxury perfusion after cardioplegia. Our data demonstrate that large doses of morphine as the sole "anaesthetic" fail to provide adequate reflex blockade during sternotomy and adversely affect myocardial oxygen balance in patients with coronary artery disease.

Adult↗
PubMed1981

[The effects of midazolam on the general circulation, cerebral blood-flow and cerebral oxygen consumption in man (author's transl)].

The effects of midazolam, 0.2 mg/kg b.w., on cerebral blood flow, cerebral oxygen consumption and brain metabolism were studied in 8 patients scheduled for intracranial aneurysm surgery. All patients were anesthetized with fentanyl and N2O; arterial pCO2 and pO2 were maintained within the normal range by controlled ventilation. Midazolam produced minimal effects on the general circulation. Cerebral blood-flow decreased about 11% while cerebral oxygen consumption essentially remained unchanged. Cerebral perfusion pressure slightly decreased due to a reduction in mean aortic pressure. In three patients with elevated intracranial pressure midazolam decreased intracranial pressure significantly while there was no change in the other patients. It is concluded that midazolam is of no harm in patients with intracranial aneurysms. Furthermore this rapidly acting drug in addition to other measures might be of some benefit in patients with elevated intracranial pressure when immediate reduction of cerebral blood volume is desired.

Adolescent↗
PubMed1980

Nutrient intake: relationships with lipids and lipoproteins in 6--19-year-old children--the Princeton School District study.

Relationships between nutrient intakes and plasma lipids and lipoproteins were studied in 949 randomly selected children, ages 6--19, in the biracial, suburban, Princeton School District. While nutrient intake increased with age in males, such age-associated increases in nutrient ingestion were much less consistent or were not significant for females. Primarily in the 6--9 and 10--12 yr age groups, white children ingested more total calories, more saturated fat, and a lower ratio of polyunsaturated to saturated (P/S) fat, more total carbohydrates, sucrose, starch, and other carbohydrates, and more protein than black children. After adjusting for age, race, sex, weight, and height, several nutrient-lipid and lipoprotein partial correlation coefficients were significant, but of relatively low magnitude. There were weak but significant inverse correlations between dietary P/S ratios and dietary carbohydrates with both total (r = -.07, -0.7) and low-density lipoprotein cholesterol (C-LDL), (r = -.07, -.08). Plasma high-density lipoprotein cholesterol (C-HDL) was inversely and significantly correlated with dietary sucrose (r = -.07); plasma triglyceride correlated positively with dietary sucrose (r = .08). Potential relationships between nutrients and lipids-lipoproteins were also examined in children at the extremes of, and in the middle of, lipid-lipoprotein distributions. After covariance adjustment for age, sex, race, and Quetelet index, children having the highest levels of C-HDL had the lowest intake of dietary carbohydrate and total calories. After further covariance adjustment for total calories, children at the highest end of the plasma cholesterol distribution had a greater intake of cholesterol and total protein than did children in the lowest end of the distribution. Nutrient intake may play a small but significant role relative to lipids and lipoproteins in children, and as such, may have importance relative to pediatric precursors of atherosclerosis.

Adolescent↗
PubMed1980

Parent-child nutrient intake interrelationships in school children ages 6 to 19: the Princeton School District Study.

Interrelationships between nutrient intakes (dietary cholesterol, total carbohydrate, saturated and polyunsaturated fat, and total calories) of parents and children were examined in 294 families (60 black, 234 white) which included at least one parent and one child in the Princeton School survey of parents and their children, ages 6 to 19. The nutrient data were collected by means of the standardized Lipid Research Clinics' collaborative 24-hr dietary recall; simple correlations and analysis of covariance were used to assess parent-child nutrient intake (per kg body weight) relationships. There were significant positive simple correlations between nutrient intake of parents and children for total carbohydrate (r = 0.28, P < 0.0001), saturated fat (r = 0.15, P < 0.01), polyunsaturated fat (r = 0.19, P < 0.001), and calories (r = 0.24, P < 0.0001); parents' intake of cholesterol did not correlate with that of their children (r = 0.004, P > 0.1). By analysis of covariance with adjustment for sex, race, age, and recall group, the parent-child association of cholesterol intake was significant (P = 0.001), and the remaining parent-child nutrient intake relationships were congruent with those observed by simple correlations. The proportion of variation of the children's nutrient intake accounted for by parental nutrient intake varied from a low of 23% for parent-child cholesterol intakes (all parents-all children) to a high of 97% for carbohydrate intake in black fathers over age 40 and their children. The multiple Rs2 for black parents-black children for nutrient intakes were higher than those for white parents-white children for carbohydrate, saturated fat, and calories. Close parent child nutrient interrelationships not only suggest that a considerable portion of lipid-lipoprotein variability may be nutritionally-environmentally determined, but may contribute to clustering of coronary heart disease risk factors in families.

Adolescent↗
PubMed1980

[Haemodynamics, coronary blood flow and myocardial metabolism in man: effects of sufentanil and fentanyl (author's transl)].

The effects of sufentanil (0.7 microgram/kg) and fentanyl (7 microgram/kg) on general and coronary haemodynamics and myocardial metabolism were studied in 6 and 9 patients without cardiovascular disease. Both drugs produced a slight reduction in heart rate, cardiac index and mean aortic pressure, whilst peripheral vascular resistance remained unchanged. There was a decrease in dp/dtmax and a slight increase in LVEDP suggesting minimal depression of myocardial contractility. Myocardial blood flow and myocardial oxygen uptake slightly decreased due to reduction in pressure-, volume- and frequency-load and dp/dtmax. With both drugs arterial concentrations of glucose, lactate, pyruvate and free fatty acids and their myocardial uptake did not change significantly. Clinically equi-anaesthetic doses of sufentanil and fentanyl produced almost identical effects on general and coronary haemodynamics. With regard to the cardiovascular actions sufentanil offers no advantage over fentanyl.

Adult↗
PubMed1980

Interrelationships between nutrient intake and plasma lipids and lipoproteins in schoolchildren aged 6 to 19: the Princeton School District Study.

Relationships between nutrient intakes and plasma lipids and lipoproteins were studied in 1,669 schoolchildren, aged 6 to 19 years; 948 were selected by random recall and 721 because of elevated plasma cholesterol or triglyceride (hyperlipidemic recall). Nutrient intake data was collected by using a 24-hour dietary recall. Median dietary cholesterol intakes for 6 to 9-year-old boys and girls in the random recall group were 222 and 230 mg/day, with polyunsaturated/saturated fat ratios of 0.34 and 0.33. For boys and girls, aged 10 to 12 years, median dietary cholesterol intakes were 296 and 235 mg/day, for 13 to 15 year olds, 343 and 237, and for 16 to 19 year olds, 418 and 221 mg/day. The dietary polyunsaturated/saturated fat ratios did not change appreciably with age. Partial correlation coefficients describing relationships between lipids, lipoproteins, and nutrients after adjustment for age, sex, race, and Quetelet index (W/H2) were calculated for all children (random and hyperlipidemic recall) after excluding children having plasma cholesterol, triglycerides, and calories less than or equal to the first or greater than or equal to the 99th percentiles for the random recall children. Plasma cholesterol was inversely and triglyceride positively correlated with dietary sucrose. Plasma low density lipoprotein cholesterol was inversely and triglyceride positively correlated with the dietary polyunsaturated/saturated fat ratio, total carbohydrate, and sugar. Potential relationships between nutrients and lipids-lipoproteins were also examined in children having low (first to tenth percentile), intermediate (45th to 55th percentile), and high (90th to 99th percentile) nutrient intake, after covariance adjustment for age, race, sex, and Quetelet index. Total plasma cholesterol fell as sucrose intake increased. Triglyceride rose along with caloric intake, total carbohydrate intake, and sucrose intake, while high density lipoprotein cholesterol levels fell with increasing caloric and sucrose intake. As dietary polyunsaturate ingestion rose from low to intermediate to high, plasma low density lipoprotein cholesterol increased. Nutrient intake may play a small but significant role relative to lipids and lipoproteins in children and, as such, may have importance relative to pediatric precursors of atherosclerosis.

Adolescent↗
PubMed1980

[The effects of midazolam on the general, coronary and cerebral circulation (author's transl)].

The effects of midazolam (0.3 mg/kg body weight) on cardiovascular haemodynamics, coronary blood flow and cerebral blood flow were studied in fentanyl/halothane anaesthetized and artifically ventilated dogs. There was only a slight decrease in mean aortic pressure and dp/dtmax. Heart rate, cardiac output, coronary bood flow and myocardial oxygen consumption essentially remained unchanged. Cerebral blood flow and cerebral oxygen consumption did not change significantly. Cerebral perfusion pressure slightly decreased due to a reduction in mean aortic pressure. Our results demonstrate that midazolam in induction doses exerts only minimal efffects on the general, coronary and cerebral circulation. Midazolam might be of benefit in clinical practice due to its rapid onset, short duration of action, minimal cardiovascular side effects and water solubility. However, these results from experimental animals have to be confirmed in man.

Anesthesia, General↗
PubMed1980

[Intensive care of severe preeclampsia-eclampsia. A report on 22 cases (author's transl)].

22 patients with severe preeclampsia-eclampsia were treated in our Intensive Care Unit from 1972 to 1978. Control of convulsions was achieved by diazepam, diphenylhydantoin and phenobarbital. In 11 comatose patients brain monitoring was carried out by frequent neurological examination and use of computerized x-ray tomography; aspiration of gastric contents was prevented by nasotracheal intubation. Brain oedema therapy included controlled hyperventilation, steroids and mannitol (7 patients). 10 patients with respiratory failure (due to pulmonary oedema, "shock lung" or aspiration pneumonitis) were treated by mechanical ventilation. Diastolic blood pressure above 100 mm Hg was reduced by hydralazine. Diuresis was induced by normalization of hypovolaemia with albumin and plasma expanders. Six patients died (27%); main causes of death included intracerebral haemorrhage, brain oedema, heart failure, acute pulmonary thromboembolism and bleeding from DIC.

Acute Kidney Injury↗