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Biomedical subjects

F Manz

Publications and source records attributed to F Manz.

At least 73 records · Page 4Linked to original sources
PubMed1995

Re-examination of the effect of hCG on plasma levels and renal excretion of dehydroepiandrosterone sulfate in healthy males.

To reinvestigate the effect of hCG on circulating and urinary dehydroepiandrosterone sulfate (DHEAS), a hCG stimulation test (5000 IU administered i.m. at 8.30 h on 3 consecutive days) was performed in 6 healthy males (aged 24 to 35 years). Blood specimens and 24-h urine samples were collected immediately before the first and directly after the last hCG administration. Contrary to previous findings in normal men, the present study revealed significant DHEAS responses after testicular stimulation with hCG: plasma DHEAS increased from 7.9 +/- 2.3 to 9.6 +/- 2.2 mumol/L (P < 0.05) and urinary DHEAS from 5.7 +/- 3.6 to 9.3 +/- 5.2 mumol/day (P < 0.05). There was also a marked rise (P < 0.05) in the urinary excretion of total 17-ketosteroid sulfates. Clear increases of unconjugated plasma dehydroepiandrosterone as well as of circulating and renally excreted androstenedione and testosterone definitely confirmed an adequate Leydig cell stimulation. Significant post-hCG changes were additionally observed for plasma and urinary 3 alpha-androstanediol glucuronide (149% and 79% increases, respectively) and for urinary cortisol (21% decrease). Significant correlations were found for the post-hCG percent increases of plasma androstenedione versus plasma DHEAS (r = 0.86) and for the percent increases of plasma testosterone versus urinary DHEAS (r = 0.98), indicating that the extent of gonadal androgen elevations in the circulation of normal men is a determinant of DHEAS increases in blood or urine. These findings provide an explanation for the frequently observed sex differences for DHEAS in adults.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Potential renal acid load of foods and its influence on urine pH.

The purpose of this study was to calculate the potential renal acid load (PRAL) of selected, frequently consumed foods. A physiologically based calculation model was recently validated to yield an appropriate estimate of renal net acid excretion (NAE); the model depends primarily on nutrient intake data. When nutrient data from actual food composition tables were used, the calculation model yielded PRAL values that ranged from an average maximum of 23.6 mEq/100 g for certain hard cheeses over 0 mEq/100 g for fats and oils to an average minimum of approximately -3 mEq/100 g for fruits and fruit juices and vegetables. By means of these PRAL data (summed according to the amounts of foods and beverages consumed daily and by an estimate of excretion of organic acids [based on body size]), the daily NAE can be calculated. This calculation methodology, primarily based on PRAL, allows an appropriate prediction of the effects of diet on the acidity of urine. For practical applicability in dietetic prevention of recurrent urolithiasis or in other fields of dietetics, the additionally determined correlation (r = .83; P < .001) between NAE and urine pH can be used to ascertain NAE target values for a desired urine pH modification.

Adolescent↗
PubMed1995

Urinary excretion of aldosterone, arginine vasopressin and cortisol in premature infants with maximum renal acid stimulation.

Of 452 low-birth-weight infants who were routinely screened for maximum renal acid stimulation (MRAS) (urine pH < 5.4), 149 episodes of incipient late metabolic acidosis (urine pH < 5.4 on 2 consecutive days) were randomly allocated to either a control group or treatment with NaHCO3 or NaCl (2 mmol/kg/day each) for 7 days. Urinary excretion of aldosterone-18-glucuronide (Aldo), arginine vasopressin (AVP) and cortisol was determined in timed urine samples. On day 1, patients with MRAS showed a tendency towards increased urinary excretion of Aldo compared with infants without MRAS. In patients who received alkali therapy, urinary excretion of Aldo, AVP and cortisol decreased or showed a trend to lower values from day 1 to day 7, whereas in patients with MRAS but no specific therapy, Aldo and AVP showed a tendency to increase. We concluded that persistent MRAS is not only characterized by a reduced rate of weight gain and a tendency to decreased nitrogen assimilation, but also increased secretion of Aldo and AVP.

Acidosis↗
PubMed1995

[Hypertrophic non-obstructive cardiomyopathy in rigid spine syndrome].

A case report is given of a 37-year-old patient suffering from rigid spine syndrome and hypertrophic non-obstructive cardiomyopathy. Clinical-cardiological and neurological findings are discussed. This is the first description of such a case in the German-language region; only two other similar publications are found in the whole literature. Follow-up is documented over a period of 10 years; apart from the early dominating neuro-muscular deficit, we saw only a mild progression of symptoms. Signs of an increasing diastolic dysfunction of the left ventricle without clinical complaints were the main cardiological findings. Because of substantial progress in elucidating the genetics of hypertrophic cardiomyopathies over recent years, case reports about the association of two different type of muscular disorders are thought to be of special interest in terms of a common etiological basis.

Adult↗
PubMed1994

The Haldane effect under different acid-base conditions in premature and adult humans.

The Haldane effect (HE) was investigated in human adults and prematures under normal metabolic acid-base conditions but at different levels of PCO2. Venous blood samples were equilibrated with low and high PCO2 in either O2 or N2. The change in plasma pH of oxygenated blood by deoxygenation did not differ between both groups. Thus, ontogenetic differences of human hemoglobin structure do not influence the net proton Haldane effect measured in terms of whole blood pH-changes. Since the present data quantitatively agree with those we reported earlier for rabbits, cats and dogs (Kiwull-Schöne et al., 1992), phylogenetic differences in hemoglobin structure of these mammalian species do not either seem to play a role in this respect. The influence of the Haldane effect on plasma pH has to be considered in blood-gas and acid-base analysis of samples with incomplete oxygenation. This is important for the indirect determination of PCO2 through pH by the equilibration method (Astrup and Schrøder, 1956), serving as reference method for determination of metabolic acid-base status and CO2 buffering capacity. Likewise, HE-correction is important for indirect estimation of metabolic acid-base status (BE and HCO-3st) from clinical routine PCO2- and pH-measurement. In spite of the vaste amount of literature on the Haldane effect in human blood, quantitative data for practical purpose are less available and still equivocal. By the present study, a strong inverse linear correlation between the HE-induced delta pH and 1g[HCO3-] could be shown over a wide range of acid-base changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-Base Equilibrium↗
PubMed1994

Progression of chronic renal failure in a historical group of patients with nephropathic cystinosis. European Collaborative Study on Cystinosis.

In a historical group of 205 patients with infantile or adolescent cystinosis treated without cysteamine, the rate of deterioration of renal function was analysed retrospectively. Patient survival curves and renal survival data are presented. Longitudinal data of serum creatinine values (n = 3280) in 157 patients were plotted for each patient, smoothed by the method of the running medians and grouped into 12 serum creatinine classes. In every patient the age at the last smoothed serum creatinine value observed in each serum creatinine class was determined. These virtual age values were then summarized per serum creatinine class, expressed as median and centiles and plotted, thus describing the "natural" course of the disease. In 9 pairs of affected siblings the rate of progression showed a median difference of about 12 months. Our data describe the "natural" course of nephropathic cystinosis and can be used as a prognostic aid for recently detected patients. The data can also be applied for the assessment of the influence of new therapeutic strategies on the rate of progression of renal failure in cystinotic patients.

Child, Preschool↗
PubMed1994

Measurement of urinary androgen sulfates without previous hydrolysis: a tool to investigate adrenarche. Validation of a commercial radioimmunoassay for dehydroepiandrosterone sulfate.

A commercial 125I radioimmunoassay designed for the quantification of dehydroepiandrosterone sulfate (DHEAS) in blood samples was tested for its direct applicability to 24-hour urine samples from children and adults. Average recoveries in parallelism and spiking experiments were found to be near 100%. Intra- and inter-assay coefficients of variation were below 10%. Urinary DHEAS concentrations determined directly by the radioimmunoassay (x) differed only slightly from corresponding radioimmunoassay values (y) obtained after C18 reversed-phase extraction and LH-20 chromatography (y = 0.85x + 0.12; r = 0.99). Cross-reactivity data from related steroids suggested only a small contribution to the DHEAS titer by other steroids. In 8-year-old children compared to preadrenarchal children (4 years old) a clearly increased median daily urinary DHEAS output could be observed both for absolute excretion data (0.163 versus 0.05 mumol/d, P < 0.01) and for excretion values related to body surface area (0.181 versus 0.071 mumol/d/1.73 m2, P < 0.05). However, this "onset of adrenarche" was no longer statistically significant when urinary creatinine was taken as adjustment parameter for renal androgen sulfate output. After correction with the individual body surface area, rises of urinary DHEAS from childhood to adulthood were nearly in the order of the literature data on age-corresponding serum increases of DHEAS. In conclusion, the direct radioimmunological quantification of DHEAS in 24-hour urine samples with subsequent correction for individual body surface area appears to present a physiologically meaningful way to assess the adrenal gland's secretory activity for this androgen sulfate.

Adrenal Glands↗
PubMed1994

Measurement of urinary androgen sulfates without previous hydrolysis: a tool to investigate adrenarche. Determination of total 17-ketosteroid sulfates.

According to published data the group of urinary total 17-ketosteroid sulfates appears to represent an index of overall adrenal androgen production, at least before the onset of puberty. To quantify total 17-ketosteroid sulfates a modified colorimetric assay based on the Zimmermann reaction was validated. 17-ketosteroid sulfates were measured without previous hydrolysis (as conjugated Zimmermann chromogens against authentic dehydroepiandrosterone sulfate (DHEAS) as assay standard) after C18 reversed-phase extraction and LH-20 chromatography. Intra- and inter-assay coefficients of variation were 8.4% (15.0%) and 5.9% (17.6%), respectively, at urinary 17-ketosteroid sulfate concentrations of 10.8 (1.9) nmol/ml. Recoveries observed in spiking and parallelism experiments varied between 88 and 102%. In a group of 4-year-old children showing a renal DHEAS output of less than 0.1 mumol/d/1.73 m2 (measured by radioimmunoassay) a relatively high median 17-ketosteroid sulfate excretion of 1.29 mumol/d/1.73 m2 was found. Older children aged 8 years as well as a group aged 12-14 years demonstrated only moderately higher urinary 17-ketosteroid sulfates whereas excretion of DHEAS/d/1.73 m2 more than tripled from age group to age group. For children from 8 years onwards, adolescents, and adults, linear regression analysis indicated that urinary DHEAS elevations seem to contribute with a constant proportion of approximately 70% to the increments of total urinary 17-ketosteroid sulfates. These findings suggest that the attainment of such a constant relationship (between the total 17-ketosteroid sulfates and their major component) from about 8 years of age onwards could represent the hormonal correlate of the completion of the continuous zona reticularis in the adrenal gland (developing around this age from a focal reticularis zone).

17-Ketosteroids↗
PubMed1994

Estimation of the renal net acid excretion by adults consuming diets containing variable amounts of protein.

The object of this study was to determine whether it is possible to reliably estimate the renal net acid excretion (NAE) produced by adults consuming different amounts of dietary protein. A physiologically based calculation model that corrects for intestinal absorption of minerals and sulfur-containing protein and assumes a rate of urinary excretion of organic acids proportional to body surface area was used to estimate NAE. Urinary excretion of different minerals and NAE was measured during the last 48 h of each of four separate 5-d diet periods in six healthy adults. On the basis of food tables, the four nearly isoenergetic diets (one lacto-vegetarian and one high- and two moderate-protein diets) were estimated to yield the following NAE values: 3.7, 117.5, 62.2, and 102.2 mEq/d, respectively. The analytically determined urinary NAE (24.1 +/- 10.7, 135.5 +/- 16.4, 69.7 +/- 21.4, and 112.6 +/- 10.9 mEq/d) corresponded reasonably well to these estimates, suggesting that the calculation model is appropriate to predict the renal NAE from nutrient intake and anthropometric data.

Acids↗
PubMed1994

Increased renal net acid excretion in prematures below 1,600 g body weight compared with prematures and small-for-date newborns above 2,100 g on alimentation with a commercial preterm formula.

In 76 low birth weight infants with an actual body weight ranging from 1,210 to 2,540 g and fed a commercial preterm formula, urine samples were collected and blood acid base status was measured on day 38 (+/- 17, mean +/- SD) of life. Infants with an actual body weight below 1,600 g demonstrated a higher daily weight gain (22 +/- 3 vs. 14 +/- 5 g/kg/day), lower blood pCO2 (35.4 +/- 5.0 vs. 38.9 +/- 3.8 mm Hg), lower urine pH (5.8 +/- 0.5 vs. 6.5 +/- 0.3), higher renal net acid (1.86 +/- 0.38 vs. 1.28 +/- 0.55 mmol/kg/day) and higher phosphorus excretion (0.67 vs. 0.52 mmol/kg/day) than infants with an actual body weight above 2,100 g. Urinary ionogram data of these 2 groups of infants show that the increased renal net acid excretion of the smaller prematures is the result of a lower urinary excretion of sodium, potassium and chloride, due to a higher daily weight gain, probably a higher retention of these minerals, and a higher urinary phosphorus excretion probably due to an age-specific lower intestinal calcium absorption, and therefore a lower rate of calcium and phosphorus retention. Considering the low renal capacity for hydrogen ion excretion, very low birth weight infants still run a considerable risk for disturbances of acid base metabolism due to the high mean level of net acid excretion in nutrition with preterm formulas and an additional age-specific augmentation of renal acid load.

Acid-Base Equilibrium↗
PubMed1994

Elevated urinary excretion of endothelin-like immunoreactivity in children with renal disease is related to urine flow rate.

Endothelin 1-21 belongs to a family of locally produced regulatory peptides with potent vasoconstrictor activity and profound renal effects. To study the biological significance of endothelin in children with renal diseases, we measured urinary endothelin-like immunoreactivity (ETir) excretion in children and adolescents (60 normal controls and 57 patients with renal disease). ETir excretion was constant during childhood and adolescence (4-18 years). Compared to these normal controls elevated urinary excretions of ETir were found in children with chronic renal failure, following renal transplantation and with idiopathic hypercalciuria (all groups p < 0.001). However, ETir excretion was unchanged in children with idiopathic steroid sensitive nephrotic syndrome, with stable chronic glomerulonephritis and in 4 patients with hemolytic uremic syndrome. Urinary ETir concentrations were similar in controls and in various patient groups. ETir excretion correlated positively with urine flow rate in normal controls (r = 0.71) and in all patients studied (r = 0.91). Fractional excretion of ETir correlated negatively with glomerular filtration rate. Eight healthy volunteers (23-27 years old, 4 female, 4 male) were studied before and after oral water load (20 ml/kg) to investigated the effect of ETir excretion on urine flow rate. Urine flow rose tenfold in response to water load and urine concentration of ETir fell only by factor 3 and urinary ETir excretion rose fivefold. These results indicate that urinary ETir excretion is related to and depends at least in part on urine flow rate. ETir excretion may so reflect a role of ETir in renal disease, especially in the diuretic state.

Adolescent↗
PubMed1993

Renal proximal and distal tubular function is attenuated in diabetes mellitus type 1 as determined by the renal excretion of alpha 1-microglobulin and Tamm-Horsfall protein.

Diabetic nephropathy is usually characterized by glomerular dysfunction; the view that tubular damage occurs as a consequence, however, has been disputed. To verify this hypothesis we compared glomerular with proximal and distal tubular parameters in 62 patients with diabetes mellitus type I. The duration of disease ranged between 0 and 39 years and the glomerular, proximal tubular, and distal tubular parameters were investigated in 24-h urine samples. Excretion of albumin as a marker of the glomerulum, alpha 1-microglobulin and N-acetyl-beta-D-glucosaminidase as parameters of proximal tubule, and Tamm-Horsfall protein as parameter of distal tubule were determined by sensitive enzyme-linked immunosorbent assays. Patients were divided into five groups (D1-D5) according to the duration of diabetes as follows: D1, less than 1 year; D2, 1-4 years; D3, 5-9 years; D4, 10-14 years; D5, longer than 14 years. Healthy individuals (n = 61) aged 3-42 years served as controls. Significantly increased excretion of proximal tubular parameters were found in early course while albumin excretion was still in the normal range. In addition, proximal tubular alpha 1-microglobulin showed an increase during the course of diabetes duration, probably indicating an early proximal tubular impairment. Distal tubular Tamm-Horsfall protein showed increasing excretion in D1-D4, which may reflect disturbance of the thick ascending loop of Henle. Our results therefore stress the importance of tubular parameters such as alpha 1-microglobulin during early diabetes mellitus type I since they may serve as early markers of renal dysfunction and may precede albumin excretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylglucosaminidase↗
PubMed1992

Assessment of the iodine status in children aged 2-3 years.

In 22 healthy toddlers (age: 2.5 +/- 0.06 years; from families living in Dortmund, FRG) measurements of iodine and creatinine concentrations were carried out in spontaneous urine samples collected in the afternoon (U1), as well as during the night (U2). Median iodine-creatinine ratios found in the "afternoon specimens" U1 were significantly elevated (p < 0.05) compared to U2 (181.3 vs. 119.5 micrograms/g). Higher values in U1 than in U2 were also obtained when total daily iodine excretion (under the assumption of an average creatinine excretion of 15 mg/kg/d for infants) was calculated and the corresponding data were related to body surface area (BSA). The results of the specimens collected during the night were (after expressing as iodine-creatinine ratio as well as after correcting for BSA) comparable with the excretion data of accurately timed 24-h urine collections obtained in a separate group of toddlers (n = 23) of nearly the same age. When the iodine-creatinine ratios established by the WHO--after standardizing with BSA--were taken as criteria for iodine deficiency, then in both study groups (spontaneous urine samples at night (U2) and timed 24-h urine collections) about half of the infants would fall in the deficiency state II with an elevated risk for iodine-deficiency goiter. It is suggested that the nutritional status of iodine can be reliably monitored (in infants) by determining iodine and creatinine concentrations in overnight urine samples and relating the data to BSA.

Body Surface Area↗
PubMed1992

Retrospective approach to explain growth retardation and urolithiasis in a child with long-term nutritional acid loading.

An infant with phenylketonuria unintentionally received a highly acidic low phenylalanine diet for 29 months. Temporary growth retardation and urolithiasis were observed, probably as direct effects of chronic acid loading. Caries at the age of 6 years may be a late consequence. This case report shows that chronic dietary acid load may cause serious side effects.

Acid-Base Equilibrium↗
PubMed1992

Low renal net acid excretion, high calciuria and biochemical signs of sodium deficiency in low-birth-weight infants fed a new low-phosphorus formula.

In 11 infants (birth weight greater than 1800 g) fed a new type of humanized formula with a low phosphorus (P) content (calcium (Ca) 11 mmol/l, P 7.2 mmol/l, sodium (Na) 8.3 mmol/l) biochemical parameters of blood, serum and urine were determined. In nine boys Ca and P balances were evaluated also. Renal net acid excretion was low (0.85 mmol/kg/day). Mean concentrations of P and Ca in urine were 0.34 mmol/kg/day (10.5 mg/kg/day) and 0.1 mmol/kg/day (4 mg/kg/day), respectively. In four infants, Ca concentration in urine was, however, greater than 0.15 mmol/kg/day) (6 mg/kg/day). In infants with birth weights greater than 1800 g fed the new, low-P formula, the low renal net acid excretion, the normal P and the high Ca concentrations in urine were comparable to term infants fed human milk. The high calciuria in several infants may be normal physiologic values. However, it remains to be established that the urinary solubility product of infants fed the new, low-P formula is in the same range as those for infants fed human milk. Unexpectedly, low urinary Na excretion (0.26 mmol/kg/day) and increased urinary excretion of aldosterone-18-glucuronide indicated biochemical evidence of Na deficiency secondary to low Na intake and a high weight gain. If the new, low-P formula is to be fed to infants with a birth weight as low as 1800 g. Na content should be higher than in mature human milk because of the often relatively higher weight gain.

Acid-Base Equilibrium↗