Biomedical subjects

J Meyburg

Publications and source records attributed to J Meyburg.

4 recordsLinked to original sources

PubMed2001

Postnatal changes in neonatal acylcarnitine profile.

++Electrospray-tandem mass spectrometry represents a powerful method for detection of inborn errors of fatty acid metabolism. In the present study, it was used to examine neonatal carnitine metabolism, which reflects fatty acid metabolism. In 70 healthy neonates, blood samples were taken from the umbilical cord and by heel-stick puncture in full-term neonates on postnatal d 5. Cord blood specimens were also obtained from 15 preterm and 10 small-for-gestational-age infants. Acylcarnitine concentrations were measured in dried blood spots by electrospray tandem mass spectrometry. Compared with cord blood, the levels of nearly all acylcarnitine species were significantly higher on the postnatal d 5, whereas free carnitine remained unchanged. Total acylcarnitine/free carnitine-ratio increased, whereas the free carnitine/total carnitine-ratio (0.54 +/- 0.05; p < 0.01) further decreased. A reduced availability of free carnitine in the early neonatal period may affect fatty acid oxidation and thus be of potential pathophysiological relevance under conditions with higher energy demands, e.g. in sepsis. Cord blood concentrations of free carnitine, total carnitine, and total acylcarnitines were strongly related to birth weight (p < 0.01). Lower umbilical artery pH, i.e. mild hypoxia, caused accumulation of mainly long-chain acylcarnitines. This implicates that long-chain acylcarnitines could serve as a parameter of perinatal asphyxia.

Carnitine↗

PubMed2000

Decreased mechanical stability of neonatal red cell membrane quantified by measurement of the elastic area compressibility modulus.

Previous studies suggest that early loss of membrane might account for the shortened life-span of neonatal red blood cells (RBC). The elastic area compressibility modulus describes the force required to achieve a defined expansion of the membrane and is thus a suitable intrinsic material property to describe mechanical stability of the RBC membrane. We studied RBC in eight cord blood samples (representing fetal blood), ten 5-day old full-term neonates and seven healthy adults. The RBC were suspended in hypotonic buffer solution and investigated using a modification of the micropipet technique by Evans et al. Cord blood RBC (204+/-33 dyn/cm) and neonatal RBC (209+/-11 dyn/cm) showed a 25% lower elastic area compressibility modulus than adult cells (278+/-26 dyn/cm; p < 0.05). Thus, less force was necessary for expansion of neonatal RBC membrane. We conclude that neonatal RBC are more susceptible to mechanical damage of their membrane than adult cells.

Adult↗

PubMed1999

Clinical symptoms, biochemical studies and therapeutic approaches in a sibship with a new congenital tubulopathy.

UNLABELLED: We report on two siblings suffering from a new congenital tubulopathy. Following normal pregnancies not complicated by polyhydramnios, severe renal losses of potassium, chloride, sodium and magnesium occurred in the first weeks after birth. Calcium metabolism was not affected. The distal tubular chloride reabsorption was considerably decreased in the two siblings (0.25 and 0.28, respectively). Secondary hyperaldosteronism, activation of the kallikrein-kinin system and elevated urinary prostaglandin excretion were observed. The effects of indomethacin, spironolactone and captopril on symptoms, electrolyte wasting, activation of renin-angiotensin-aldosterone and kallikrein-kinin system and prostaglandin synthesis were studied. In spite of persisting elevation of prostaglandin synthesis, captopril decreased electrolyte wasting, polyuria and hyperaldosteronism most effectively. CONCLUSION: We delineate an apparently new disorder characterized by a postnatal onset, an extremely decreased chloride reabsorption with extensive hyperchloriduria and hypermagnesiuria in the presence of normal calcium metabolism. The disorder can be distinguished from other tubulopathies with hypokalaemic alkalosis.

Absorption↗

PubMed1996

Severe hyperchloriduria-hyperkaliuria: a new congenital renal tubular abnormality?

A female infant, aged 5 weeks, had metabolic alkalosis associated with severe electrolyte disturbances. In addition to findings typically seen in patients with Bartter syndrome or hyperprostaglandin E syndrome, she had massive urinary excretion of prostaglandins E2 and E-M, normal calcium metabolism, hyperphosphaturia, and severe hyperchloriduria and hyperkaliuria with limited response to indomethacin. These findings may represent a new congenital renal tubular abnormality.

Bartter Syndrome↗