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Biomedical subjects

J Kerner

Publications and source records attributed to J Kerner.

At least 55 records · Page 3Linked to original sources
PubMed1989

A skills training approach to smoking prevention among Hispanic youth.

The present study was designed to test the feasibility, acceptability, and effectiveness of a 15-session smoking prevention intervention with a predominantly hispanic (74%) sample of seventh-grade students (N = 471) in eight urban schools in the New York area. The smoking prevention curriculum teaches social resistance skills within the context of a broader intervention promoting general personal and social competence and was implemented in this study by regular classroom teachers. Results of logistic regression analyses provided preliminary evidence of the efficacy of this type of smoking prevention strategy with urban minority youth when implemented with a reasonable degree of fidelity. The significance of these findings is that they provide support for the generalizability of an approach previously found to be effective with white middle-class populations to a predominantly hispanic inner-city population.

Adolescent↗
PubMed1989

Quantitation of urinary carnitine esters in a patient with medium-chain acyl-coenzyme A dehydrogenase deficiency: effect of metabolic state and L-carnitine therapy.

Urinary carnitine esters were quantitated in an infant with medium-chain acylcoenzyme A dehydrogenase deficiency by means of a highly sensitive and specific radioisotopic exchange high-pressure liquid chromatography method. During fasting, the excretion of free carnitine and of acetylcarnitine, octanoylcarnitine, and hexanoylcarnitine was increased. The fractional tubular reabsorption of free carnitine was decreased, suggesting a renal leak of free carnitine. In the symptom-free, fed state, only minor amounts of free carnitine and of short-chain acylcarnitine, octanoylcarnitine, and hexanoylcarnitine were present in urine, and carnitine loss occurred in the form of "other" carnitine esters not exceeding that of control subjects. During L-carnitine therapy, the excretion of free carnitine, short-chain acylcarnitine, octanoylcarnitine, and hexanoylcarnitine, and particularly of "other" carnitine esters, was increased, suggesting a possible detoxifying effect of administered carnitine that is not confined to the elimination of octanoic and hexanoic acids. The employed method detects very low urinary concentrations of octanoylcarnitine and hexanoylcarnitine (less than 1 mumol/L) characteristic of medium-chain acyl-coenzyme A dehydrogenase deficiency and may be useful in screening for this disease, which has been associated with sudden infant death.

Acetylcarnitine↗
PubMed1989

[Grade III open fracture of the femoral diaphysis in a polytraumatized child].

Authors describe the case of a 7.5 years old girl run over and with polytrauma, whose bilateral fracture of the femoral diaphysis was treated with osteosynthesis. The operative indication was the III. degree open fracture on one side. Anatomical reduction was performed on both sides, with DC plate on the closed side and with fixateur externe after insertion of adaptation screws on the open one. The missing soft tissues were substituted with delayed split thickness mashgraft flaps. The injuries healed with good function. If the operative treatment of the femoral diaphysis is founded the lamellar osteosynthesis or the fixateur externe method is suggested.

Accidents, Traffic↗
PubMed1988

Enzymes of carnitine acylation. Is overt carnitine palmitoyltransferase of liver peroxisomal carnitine octanoyltransferase?

Liver mitochondria prepared by differential centrifugation are contaminated by significant quantities of peroxisomes and microsomal fractions. 'Easily solubilized carnitine palmitoyltransferase' prepared from liver mitochondria is thought to originate from the outer surface of the mitochondrial inner membrane. We have characterized the carnitine palmitoyltransferase activities of freeze-thaw extracts of rat liver mitochondrial preparations. Chromatography on Sephadex G-100 yields two broad peaks of carnitine decanoyltransferase activity: one eluted at the end of the void volume, which can be removed (precipitated) by ultracentrifugation; the second peak represents the soluble activity and is eluted at an Mr near 70,000. The activity in the soluble peak is precipitated by an antibody raised against carnitine octanoyltransferase purified from mouse liver peroxisomes. In contrast, antibody raised against carnitine palmitoyltransferase purified from liver mitochondrial membranes had no effect (P. Brady & L. Brady, personal communication). The carnitine acyltransferase activities of the Mr-70,000 peak in the presence or absence of Tween 20 showed maximum activity with decanoyl-CoA and about one-third of this activity with palmitoyl-CoA, similar to peroxisomal carnitine octanoyltransferase. These data show that 7500 g preparations of liver mitochondria isolated by differential centrifugation are enriched by peroxisomal carnitine octanoyltransferase (approx. 20% of the protein of the fraction is peroxisomal) and indicate that this enzyme may be the one reported as 'overt' or 'easily solubilized' mitochondrial carnitine palmitoyltransferase.

Acylation↗
PubMed1987

Effect of malonyl-CoA on the kinetics and substrate cooperativity of membrane-bound carnitine palmitoyltransferase of rat heart mitochondria.

The effect of malonyl-CoA on the kinetic parameters of carnitine palmitoyltransferase (outer) the outer form of carnitine palmitoyltransferase (palmitoyl-CoA: L-carnitine O-palmitoyltransferase, EC 2.3.1.21) from rat heart mitochondria was investigated using a kinetic analyzer in the absence of bovine serum albumin with non-swelling conditions and decanoyl-CoA as the cosubstrate. The K0.5 for decanoyl-CoA is 3 microM for heart mitochondria from both fed and fasted rats. Membrane-bound carnitine palmitoyltransferase (outer) shows substrate cooperativity for both carnitine and acyl-CoA, similar to that exhibited by the enzyme purified from bovine heart mitochondria. The Hill coefficient for decanoyl-CoA varied from 1.5 to 2.0, depending on the method of assay and the preparation of mitochondria. Malonyl-CoA increased the K0.5 for decanoyl-CoA with no apparent increase in sigmoidicity or Vmax. With 20 microM malonyl-CoA and a Hill coefficient of n = 2.1, the K0.5 for decanoyl-CoA increased to 185 microM. Carnitine palmitoyltransferase (outer) from fed rats had an apparent Ki for malonyl-CoA of 0.3 microM, while that from 48-h-fasted rats was 2.5 microM. The kinetics with L-carnitine were variable: for different preparations of mitochondria, the K0.5 ranged from 0.2 to 0.7 mM and the Hill coefficient varied from 1.2 to 1.8. When an isotope forward assay was used to determine the effect of malonyl-CoA on carnitine palmitoyltransferase (outer) activity of heart mitochondria from fed and fasted animals, the difference was much less than that obtained using a continuous rate assay. Carnitine palmitoyltransferase (outer) was less sensitive to malonyl-CoA at low compared to high carnitine concentrations, particularly with mitochondria from fasted animals. The data show that carnitine palmitoyltransferase (outer) exhibits substrate cooperativity for both acyl-CoA and L-carnitine in its native state. The data show that membrane-bound carnitine palmitoyltransferase (outer) like carnitine palmitoyltransferase purified from heart mitochondria exhibits substrate cooperativity indicative of allosteric enzymes and indicate that malonyl-CoA acts like a negative allosteric modifier by shifting the acyl-CoA saturation to the right. A slow form of membrane-bound carnitine palmitoyltransferase (outer) was not detected, and thus, like purified carnitine palmitoyltransferase, substrate-induced hysteretic behavior is not the cause of the positive substrate cooperativity.

Acyl Coenzyme A↗
PubMed1987

Pivampicillin-promoted excretion of pivaloylcarnitine in humans.

Pivampicillin treatment of seven children (five boys and two girls) for 7 days significantly reduced the amounts of total acid-soluble carnitine, free carnitine, and long-chain acylcarnitines and increased the amounts of acid-soluble acylcarnitine in plasma. The fasting plasma levels of 3-hydroxybutyrate at the end of treatment were 15% of the control value. The levels of free fatty acids were decreased, whereas triglyceride levels were unaffected, indicating impaired fat metabolism. Daily urinary excretion of total carnitine was four to five times higher than controls after the first day of treatment, although the amounts of free carnitine and acetylcarnitine were decreased. The urinary acylcarnitines were isolated and characterized by gas chromatography/electron impact mass spectrometry and fast-atom bombardment mass spectrometry. Pivaloylcarnitine was the predominant urinary acylcarnitine; it represented greater than 96% of the increased excretion of total carnitine and 75-80% of the total conjugated pivalic acid. The renal clearance of acylcarnitines was comparable to that of creatinine, indicating no reabsorption of pivaloylcarnitine. These data suggest a detoxification function of carnitine for pivalic acid in humans.

Acetylcarnitine↗
PubMed1987

Energy balance in rats with obesity-producing hypothalamic knife cuts: effects of adrenalectomy.

Rats with obesity-producing, hypothalamic knife cuts (KC) were fed a purified high fat diet for 9 wk. KC rats consumed more energy (+70-100%) and retained energy with a much higher efficiency than control rats. Adrenalectomy of KC rats 1 wk (before gross obesity was evident) or 5 wk (when KC rats were 70% overweight) after KC surgery caused a reduction in energy intake to levels approximating those of control rats. Furthermore, energy retention in adrenalectomized KC rats was depressed more than could be explained on the basis of the reduction in energy intake. Two factors associated with the reduction in energy retention, urinary excretion of norepinephrine, an indicator of sympathetic nervous system activity, and GDP binding to brown adipose tissue mitochondria, an indicator of the thermogenic capacity of the tissue, were higher in vadrenalectomized KC rats than in pair-fed KC rats. Removal of the adrenals not only suppressed hyperphagia in KC rats fed a high fat diet, but also increased energy expenditure per kilocalorie consumed.

Adipose Tissue, Brown↗
PubMed1987

Effects of oral L-carnitine supplementation in low-birth-weight premature infants maintained on human milk.

Effects of oral L-carnitine supplementation on fat and protein metabolism have been studied in 20 low-birth-weight premature infants (mean weight at birth 1.519 g, range 1,200-1,880 g) fed with pooled pasteurized human milk. Throughout 7 consecutive days, started at various postnatal ages (range 10-33 days) infants were fed exclusively with milk containing 300 nmol/ml L-carnitine as added supplement. The amount of extra carnitine intake ranged from 42.6 to 72.0 mumol/kg/day. Until day 5 of supplementation there was a continuous increase in the daily urinary excretion of total carnitine, which levelled off thereafter, corresponding approximately to 50% of the extra L-carnitine intake, indicating that a part of the supplement was retained by the body. Total, free and esterified carnitine levels were significantly elevated in the plasma at the end of the study period. The increased levels of acylcarnitines in plasma and urine indicate that the carnitine supplement was taken up by tissues and entered the intermediary metabolism. Plasma triglyceride level was decreased, whereas 3-hydroxybutyrate level was increased at the end of supplementation, indicating an enhanced fat utilization. Plasma and urine analysis also revealed an altered nitrogen handling. There was a marked decrease in plasma urea level as well as a significant fall in the urea and total N excretion, with a trend of decrease in excretion of 3-methylhistidine, suggesting a reduced amino acid and protein catabolism during L-carnitine supplementation.

Administration, Oral↗
PubMed1987

Effect of chronic valproic acid treatment on plasma and urine carnitine levels in children: decreased urinary excretion.

Plasma levels and urinary carnitine excretion rates were determined in children treated with valproic acid (n = 11) and in age and sex matched controls (n = 11). Urine was collected throughout two consecutive 24 h periods in both groups, and blood samples were taken on the first day of collection after an overnight fast. The plasma level of total and free carnitine was significantly lower in the treated group (24.3 +/- 2.2 vs 34.9 +/- 2.4 and 16.8 +/- 1.8 vs 26.5 +/- 2.1 nanomol/ml; values are means +/- SEM), while there was no significant alteration in the acylcarnitine fraction. In the treated group of children a significant reduction was found in the plasma beta-hydroxybutyrate level indicating a limited fatty acid utilization (23.2 +/- 2.5 vs 81.9 +/- 7.8 nanomol/ml). Urinary total and free carnitine decreased from 286.4 +/- 57.8 to 120.8 +/- 18.2 and from 154.3 +/- 33.6 to 21.2 +/- 5.8 mumol/day, respectively; the acyled fraction was not significantly reduced. In one child, urinary carnitine excretion was followed during the first ten days of treatment. After the 2nd day a decrease of the total and free fraction was observed, confirming previous data obtained during chronic VPA treatment. It has been concluded that the decreased plasma carnitine associated with chronic VPA treatment is not a result of an increased excretion rate, but more likely the consequence of a relatively insufficient endogenous carnitine synthesis. The decreased plasma BOB level probably due to limited fatty acid utilization might also be a metabolic consequence of depressed carnitine concentration.

Adolescent↗
PubMed1987

Sclerosing cholangitis associated with chronic cryptosporidiosis in a child with a congenital immunodeficiency disorder.

Primary sclerosing cholangitis (PSC) in children is a rare and incurable disorder of unknown etiology. We report an immunodeficient child with chronic cryptosporidiosis of the biliary tract leading to clinical, pathological, and radiographic findings consistent with PSC. This case documents the ability of Cryptosporidium to disseminate to extraintestinal organs, and suggests that chronic cryptosporidial infection of the biliary tract may be one etiological mechanism producing sclerosing cholangitis in immunodeficient children. The increased incidence of PSC in immunodeficient children may in part be due to their inability to resolve infections of the biliary tract, which may result in sclerosing cholangitis mimicking PSC. We submit that an aggressive diagnostic workup should be performed to rule out an infectious etiology of sclerosing cholangitis in immunodeficient patients who have findings of PSC, because specific chemotherapy against the infecting organism would potentially arrest progressive biliary obliteration.

Adolescent↗
PubMed1986

Impaired thermoregulation in cold-exposed rats with hypothalamic obesity.

Rats with obesity-producing, hypothalamic knife cuts were fed a high fat diet and placed in the cold (2 degrees C) for six days starting 3, 11, or 24 days after surgery. Between surgery and cold exposure, knife-cut rats consumed 90% to 122% more energy and gained more weight (32 +/- 4, 112 +/- 5, and 241 +/- 9 g) than sham-operated rats (15 +/- 2, 34 +/- 2, and 58 +/- 3 g). When exposed to cold, sham-operated rats increased (22% to 30%) energy intake whereas knife-cut rats decreased (5% to 51%) intake. After 24 hours at 2 degrees C body temperatures of knife-cut rats were 1.2, 0.7, and 0.7 degrees less than those of control rats; body temperatures continued to decrease to 2.9, 3.0 and 2.5 degrees less than control rats after six days at 2 degrees C. Fasting for 12 hours at 2 degrees C caused a further reduction in body temperature to 4.9, 4.8, and 5.9 degrees less than in control rats. Cold exposure increased urinary excretion of norepinephrine and epinephrine (indicators of sympathoadrenal activity) in all rats. Guanosine diphosphate (GDP) binding to brown adipose tissue (BAT) mitochondria (an indicator of the thermogenic capacity of the tissue) was similar in cold-exposed, knife-cut, and sham-operated rats. Cold acclimation before hypothalamic knife-cut surgery prevented the cold-induced decrease in body temperatures of knife-cut rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue, Brown↗
PubMed1986

Oral L-carnitine supplementation in low-birth-weight newborns: a study on neonates requiring combined parenteral and enteral nutrition.

Effect of L-carnitine supplementation on plasma ketone body (KB) and triglyceride (TG) concentrations was studied in ten premature infants requiring combined enteral and parenteral nutrition. At the second week of life (9 to 14 days of age) the infants were randomly divided into two groups. Five of them (plasma carnitine value, 33.77 +/- 2.48 mumol/l; mean +/- SEM) received oral L-carnitine supplementation (60 mumol/kg daily) added to pasteurized pooled human milk for seven consecutive days; additional five (plasma carnitine value, 36.70 +/- 5.19 mumol/l) served as controls. Composition of the daily diet was nearly constant in the study period. On the seventh day, prior to an Intralipid infusion, plasma carnitine and ketone body levels were significantly increased in the supplemented group as compared to controls or to previous values of the same group. In response to lipid infusion the fat load induced ketone body production was significantly higher in the supplemented group as compared to controls, whereas the triglycerides reached higher levels in the control group. It is suggested that L-carnitine supplementation in low-weight newborns promotes ketone body formation from endogenous stores as well as from exogenous fat supply, and thus may enhance triglyceride utilization.

Carnitine↗
PubMed1986

Uptake of beta-hydroxybutyrate, acetoacetate and glucose by the forearm of the newborn infant.

Forearm muscle metabolism was studied in twelve appropriate for gestational age premature infants suffering from respiratory distress. Arterial blood was obtained by puncture of the radial artery as clinically indicated for measuring oxygen tension, and venous blood samples were taken from the same arm's deep brachial vein. This arrangement allowed to study the arterial-deep venous differences of beta-hydroxybutyrate, acetoacetate and glucose in simultaneously taken blood samples. Net muscular uptakes of beta-hydroxybutyrate and glucose were observed, however, in four studies a virtual net production of acetoacetate was found. The arterial-deep venous concentration differences of both ketone bodies correlated positively with their arterial concentration within the 20 to 120 nanomol/ml range. Such a correlation was not observed in glucose utilization. It is concluded that forearm muscles in the neonate take up ketone bodies and this is in part concentration regulated.

3-Hydroxybutyric Acid↗