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Biomedical subjects

F Manz

Publications and source records attributed to F Manz.

At least 91 records · Page 5Linked to original sources
PubMed1992

Why is the phosphorus content of human milk exceptionally low?

The phosphorus supply of children and adults is adequate, and usually in excess. Therefore, it is surprising that in breast-fed infants phosphorus intake is very low. This is very rare among mammals. In infants three pathophysiological mechanisms argue in favour of a low, but adequate phosphorus intake in the presence of a balanced ratio of calcium to phosphorus. A low intestinal phosphorus concentration is an essential condition of an acid pH of the faeces, inhibiting the growth of potentially pathogenic germs. Owing to the characteristic renal physiology of the newborn, a small metabolic phosphorus surplus results in a high serum phosphorus level, a well-known risk factor for several disorders, e.g. hypocalcaemic tetany. During infections, impairment of intestinal calcium but not of phosphorus absorption results in an increased phosphorus and renal net acid excretion. Considering the low renal capacity for acid excretion in newborns, a high intake of calcium and phosphorus is a risk factor for the development of metabolic acidosis. It is thought that all three pathophysiologic mechanisms were effective in the biochemical evolution of humans, selecting women with a low phosphorus milk and infants with a constant high intestinal absorption rate of phosphorus.

Acid-Base Equilibrium↗
PubMed1991

Unaltered pulsatile and circadian TSH release in euthyroid patients with endemic goitre.

To evaluate the pathophysiological role of TSH in goitrogenesis we investigated pulsatile TSH secretion in 11 patients with a non-toxic goitre and in 11 healthy controls. Thyroid volume was 40 +/- 10 ml in the goitre group and 15 +/- 4 ml in the controls as measured by ultrasound. Blood was sampled continuously via an indwelling venous catheter at 10-min intervals over 24 h. Neither the mean 24-h serum TSH levels (goitre 1.1 +/- 0.5 vs controls 0.9 +/- 0.4 mU/l) nor the nocturnal surge of TSH were significantly different between the two groups. The average of the TSH pulse frequency (goitre 10.8 +/- 3.7 vs controls 9.6 +/- 3.5 pulses/24-h) and of the TSH pulse amplitude (goitre 0.4 +/- 0.2 vs controls 0.3 +/- 0.1 mU TSH/l) as analysed by DESADE programme (detection of secretory activity by discrete deconvolution) did not differ in the two groups. Furthermore, there was no correlation between the volume of the thyroid gland and the dynamics of the TSH secretion. We conclude that our data do not suggest a relevant pathophysiological role of TSH secretion in the development of non-toxic goitre in man.

Adult↗
PubMed1991

Renal handling of hydrogen ion excretion in relation to maturity indices in premature infants fed human milk.

In 40 premature infants fed human milk with an actual gestational age of 261 +/- 16 days and an actual body weight of 1.06-2.75 kg, 44 urine samples were collected, and blood acid-base status was measured on day 32 (+/- 16) of life. In the urine, the following results (mean +/- SD) were obtained: urine pH 6.05 +/- 0.65, titratable acidity 0.24 +/- 0.14 mmol/kg/day, ammonium 0.78 +/- 0.25 mmol/kg/day, net acid excretion 0.83 +/- 0.47 mmol/kg/day. There was no significant correlation between renal net acid or ammonium excretion and actual body weight. However, urine pH was positively correlated with body weight. Obviously, premature infants with an actual body weight below 1.5 kg need a higher stimulation of renal hydrogen ion secretion to excrete the same amount of ammonium than those with an actual body weight of about 2.5 kg. The limited renal acidification capacity of very low birth weight infants is a risk factor for the development of late metabolic acidosis.

Acid-Base Equilibrium↗
PubMed1991

Effect on renal net acid excretion of various mineral contents in three lots of a common pre-term formula.

Three common lots (A, B, C) of a common formula for pre-term infants, which contained unintended, high differences in mineral contents were fed consecutively in a neonatal unit. In each feeding period parameters of calcium-phosphorus and acid-base metabolism were determined prospectively. Infants fed lot C showed unexpectedly high renal net acid excretion. In order to discover the origin of this different renal net acid excretion, the urinary concentration of further electrolytes, sulfate, urea and organic acids were determined retrospectively in three randomly selected groups with 10 pre-term infants each. Infants fed lot C showed a higher renal net acid excretion (2.97 mmol/kg per day) than infants fed lot A (1.75 mmol/kg per day) or lot B (1.72 mmol/kg per day). Based on the data of mineral and nitrogen intake and the urinary values of all main ions and urea it is assumed that the increased renal acid load in infants fed lot C is due to the additive effect of different mineral concentrations resulting in a low "alkali excess" (Na + K - Cl) of lot C and a decreased protein assimilation. The production of infant formulas for prematures should be more closely monitored to avoid marked deviation of the mineral contents in individual lots from the concentrations shown on the label.

Acid-Base Equilibrium↗
PubMed1991

Circadian rhythms of urine osmolality and renal excretion rates of solutes influencing water metabolism in 21 healthy children.

Circadian rhythms of urine excretion, urine osmolality and renal excretion rates of sodium, chloride, potassium, creatinine and urea were studied for 3 days at home in 21 healthy children aged 6-11 years. Urine production as well as renal excretion rates of all solutes studied increased significantly during daytime and had minimum values at night. The peak of potassium and chloride excretion rates occurred earlier in the day than that of sodium. Considering all children together, no circadian rhythm was seen for urine osmolality. However, 9 children had evident but individually different rhythms of urine osmolality, changes which did not seem to correspond to the daily distribution of water intake. Circadian rhythmicity of urine osmolality and renal excretion rates of the main solutes should be considered in diagnostic and therapeutic procedures concerning fluid and electrolyte metabolism.

Body Water↗
PubMed1990

Biochemical evidence for the need of long-term mineral supplementation in an extremely low birth weight infant fed own mother's milk exclusively during the first 6 months of life.

In an extremely low birth weight infant fed expressed own mother's milk exclusively during the first 6 months of life, introduction of a human milk fortifier resulted in improvement of biochemical alterations consistent with metabolic bone disease of prematurity. Attempts to discontinue fortification at 9 weeks (discharge) and 21 weeks of age induced deterioration of biochemical parameters, demonstrating a persistent need for mineral supplementation during the whole period of breast-feeding. The effects of long-term human milk fortification are discussed.

Bone Diseases, Metabolic↗
PubMed1990

Interrelation between whole-body turnover rates of RNA and protein.

In our search for new non-invasive methods to determine metabolic and nutritional state, we have identified several specific, modified, urinary one-way catabolites of rRNA, tRNA and mRNA which permit the assessment of the whole-body turnover of these RNA classes. A comparison of the steady-state turnover of RNA and the proteins actin plus myosin (determined using urinary 3-methylhistidine) in preterm infants and adults showed that preterm infants have about 3 times higher average turnover rates per unit body weight than adults of tRNA and rRNA as well as of actin plus myosin, whereas calculated mRNA turnover was 6 times higher in preterm infants than in adults. These as well as our recent observations of RNA turnover in different mammals are compared here with data on whole-body protein turnover and basal metabolic rates (BMR) in different mammalian species including man, for which data are available. The turnover rates of tRNA, rRNA, protein and energy (BMR) can be described by the relation, turnover = const. x body mass (exp.), the extrapolated exponents being 0.69-0.78. This suggests a common underlying principle, possibly energy turnover, as cause for the coordinated whole-body turnover rates of RNA and protein in the steady state.

Adult↗
PubMed1990

[Contents and batch-dependent variations of mineral substances in milk formula for premature infants and possible effects on renal acid burden].

The mineral contents of Na, K, Ca, Mg, Cl and P was determined in different batches of 5 preterm formulas. The purpose of this study was 1st to investigate whether the analytical data are in agreement with the specifications of the manufactures and 2nd whether there are large variations between different batches of the same formula. For each analyzed mineral we found marked differences between the specifications and our measurements in at least one of the formulas. In these cases the differences between the labels and the medians of the analytical data were larger than half of the range of all determinations of the respective formula. Without exception the mean values for K were all clearly lower than the specifications of the producers. In 4 of the 5 premature formulas variation coefficients greater than 10% were observed for at least one mineral. The results show that coincidental variations of mineral contents in different batches can result in a disadvantageous mineral composition because of synergistic effects on metabolism. In this context the importance of the sum of Na and K over Cl in premature formulas is stressed with regard to renal acid excretion. The introduction of more stringent quality standards is proposed.

Acid-Base Equilibrium↗
PubMed1989

Effects of two levels of intake of chloride, potassium, and calcium on mineral and acid-base metabolism in premature infants.

Growth (weight, length, mid-upper arm circumference), acid-base status, serum electrolyte levels, and selected parameters of urine (creatinine and electrolyte levels, urine pH, renal net acid excretion, levels of metabolites of aldosterone) were determined serially from the 10th to the 32nd days for 4 weeks in 21 premature infants (birth weight, 1,100-2,000 g) fed either formula A or formula B (formula B was formula A supplemented with chloride, potassium, and calcium). Premature infants fed formula B showed a higher weight gain (31 versus 28.2 g/day), a higher increment of middle-upper arm circumference (0.31 versus 0.24 cm/week), and a decreased renal net acid excretion (1.24 versus 1.92 mEq/kg/day). Almost all premature infants fed formula A and some with a high growth rate receiving formula B showed hypochloruria corresponding to chloride deficiency. Premature infants fed unsupplemented humanized formulas may have an inadequate intake of minerals.

Acid-Base Equilibrium↗
PubMed1989

Effect of calcium supplementation on calcium and phosphorus balance and renal net acid excretion in preterm infants fed a standard formula.

In 19 preterm infants fed a standard formula for prematures (calcium (Ca) 13.5 mmol/l; phosphorus (P) 12.9 mmol/l), biochemical parameters of blood, serum and urine were determined before and during supplementation with Ca-L-lactate (final Ca concentration 20 mmol/l). In 8 preterm boys Ca and P balance were evaluated in addition. During Ca supplementation, the serum Ca levels, urine pH (without supplement 6.31, with supplement 6.73), and calciuria (46 mumol/kg/d vs. 98 mumol/kg/d) were increased, and urinary P (1.05 mmol/kg/d vs. 0.65 mmol/kg/d) and net acid excretion (1.70 mEq/kg/d vs. 0.89 mEq/kg/d) were decreased. Balance studies showed increased net intestinal Ca absorption during supplementation (37% vs. 56%) as well as improved Ca (0.8 mmol/kg/d vs. 1.85 mmol/kg/d) and P retention (0.97 mmol/kg/d vs. 1.45 mmol/kg/d). These data show that increased Ca intake given to optimize the Ca:P ratio improves mineral retention in preterm infants fed a standard formula. Ca and P intake should be thoroughly balanced to avoid side-effects like hypercalciuria or high renal net acid excretion.

Calcium↗
PubMed1988

Do children have an adequate fluid intake? Water balance studies carried out at home.

In 21 healthy children aged 6-11 years water balance studies were performed for 3 days at home. Water intake was assessed from dietary records based on the precise weighing method and water loss was calculated from repeated measurements of body weight and urine collection. Mean values (+/- SD) of all parameters of water balance are presented. Water intake from food and drinks without metabolic water of 43.0 +/- 11.5 g/kg/day or 0.78 +/- 0.17 g/kcal (0.19 +/- 0.04 g/kJ) resulted in a urine volume of 22.5 +/- 7.7 g/kg/day and an osmolality of 24-hour urine samples of 756 +/- 199 mosm/kg. From these data water intake seems to be low in these children. In school-aged children water intake from food and drinks of 1 ml/kcal (0.24 ml/kJ) as recommended for adults (Recommended dietary allowances, 1980) would seem adequate, theoretically resulting in a urine volume of 35 +/- 14 g/kg/day and urine osmolality of 516 +/- 182 mosm/kg based on the data in our children.

Age Factors↗
PubMed1987

Fanconi-Bickel syndrome.

Clinical, biochemical, functional and morphological data are presented in nine infants, children and adults, with Fanconi-Bickel syndrome. Long-term follow-up studies show severe growth retardation, partly compensated for by late onset of puberty. Glomerular filtration rate is normal or slightly decreased. Renal tubular dysfunction is characterized by a specific pattern of impaired proximal tubular transport mechanisms, with marked impairment of glucose transport. The utilization of glucose and galactose is defective, whereas fructose metabolism seems to be normal. Glycogenosis of the liver may be an epiphenomenon. Glycogen accumulation in the kidney is limited to the proximal tubule, with maximal levels in the straight part. The Fanconi-Bickel syndrome is a defined clinical entity which is distinguished from other inherited metabolic diseases by complex defects of renal tubular transport and other forms of glycogenosis.

Adolescent↗
PubMed1987

[Significance of iodized table salt on the iodine supply of adults and children].

In 42 families from Dortmund iodine intake by dairy products, sea-fish and iodized salt used at home was measured. Urinary excretion of iodine in 24 h-urine samples and spontaneous samples before and after the use of iodized salt was estimated in each person. TSH levels were measured in 71 persons before and after the introduction of iodized salt. Mean daily intake of iodine by milk and sea-fish was calculated as 53 micrograms/d in adults and adolescents (greater than 12 years, n = 95), 57 micrograms/d in pupils (greater than 6- less than 12 years, n = 36) and 40 micrograms/d in small children (less than 6 years, n = 20). The median of iodine excretion in 24 h-urine samples before the use of iodized salt (after 6 months of use) was 61 micrograms/d (77 micrograms/d) in men, 30 micrograms/d (49 micrograms/d) in boys aged more than 12 years, 39 micrograms/d (49 micrograms/d) in women and girls aged more than 12 years, 21 micrograms/d (33 micrograms/d) in pupils and 21 micrograms/d (28 micrograms/d) in small children. There was a corresponding increase of iodine excretion in spontaneous urine samples. These data agree with our estimation of an additional intake of about 20 micrograms iodine/d. In 11 children and adolescents with stage I goiter serum levels of TSH tended to be lower after using iodized salt for 6 months. An adequate additional intake of iodine of about 100 micrograms/d in German adults can not be met by the exclusive use of iodized salt (20 micrograms/g) at home, as the intake of iodized salt is far below the 5 g/day necessary to meet this goal.

Adolescent↗
PubMed1986

[Iodized salt consumption and sodium chloride metabolism].

In 42 families from Dortmund common table salt was replaced by iodized salt. In adults and adolescents over 12 years (n = 95) median intake of iodized salt at home was 1.9 g/d, in schoolchildren between 6 and 12 years (n = 36) 1.6 g/d and in small children (n = 20) 0.9 g/d. The range of the individual intake of iodized salt was large. Only 7% of the adults and the adolescents used more than 5 g/d. Only 39% of the daily consumption of iodized salt was directly added to the food consumed, whereas 61%, used e. g. to season cooking water, was only partially ingested. Overall urinary excretion of sodium chloride within the groups studied did not differ from data from other German groups. In men and boys median urinary excretion of sodium chloride was 12.2 g/d, in women and girls 9.5 g/d, in schoolchildren 5.9 g/d, and in small children 3.5 g/d. The consumption of iodized salt at home with an iodine concentration of 20 micrograms/g may increase iodine intake in adults and adolescents by about 20 micrograms/d. As an iodine deficit of about 100 micrograms/d cannot be met by regular consumption of iodized salt at home the present concept for prophylaxis of iodine deficiency should be revised.

Adolescent↗