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Biomedical subjects

G Boehm

Publications and source records attributed to G Boehm.

At least 19 recordsLinked to original sources
PubMed1992

Postnatal development of liver and exocrine pancreas in polycythemic newborn infants.

In 35 newborn infants appropriate for gestational age the influence of neonatal polycythemia (venous hematocrit greater than 60% measured between the second and fourth hour of life) on development of enterohepatic circulation of bile acids, activities of pancreatic enzymes in duodenal juice, and the effects of hemodilution were studied during the second week of life. A significant correlation was found between the initial hematocrit and both the bile acid concentration in serum and lipase and trypsin activity in duodenal juice. Of 35 infants, 10 were not treated with hemodilution due to asymptomatic polycythemia; they had the highest concentration of serum bile acids associated with the lowest lipase and trypsin activity in duodenal juice. However, the 25 infants treated with hemodilution also showed serum bile acid concentrations and lipase and trypsin activity in duodenal juice out of the normal range when compared to normocythemic infants. These data indicate that, during the first days of life, polycythemia results in a delayed postnatal development of enterohepatic circulation of bile acids and exocrine pancreas functions independently from the occurrence of clinical symptoms. Thus, it can be concluded that, on the first day of life, all polycythemic infants should be treated with hemodilution. Moreover, the nutritional management of these infants must also account for the limited functional capacity of the gastrointestinal tract.

Algorithms↗
PubMed1992

Macromolecular absorption in small-for-gestational-age infants.

Using human alpha-lactalbumin as a marker protein, macromolecular absorption was studied in 40 preterm infants, appropriate for gestational age (AGA), in 12 AGA term infants and in 18 preterm infants, small for gestational age (SGA). The absorption of alpha-lactalbumin was measured as concentration in serum after a human milk feed and expressed as micrograms alpha-lactalbumin/l serum/l human milk/kg body weight on day 7, 14, 21 and 42 after delivery. The serum concentration of alpha-lactalbumin was correlated negatively with maturity and postnatal age. In the SGA infants, the concentration of alpha-lactalbumin was significantly higher than in the AGA infants of similar gestational age. The data show that intrauterine growth retardation causes a delayed postnatal decrease in macromolecular absorption. This may indicate delayed intestinal maturation.

Birth Weight↗
PubMed1992

Tomographic imaging of opaque and low-contrast objects in range-independent waveguides.

A feasibility study is presented for acoustic tomographic imaging of arbitrarily shaped objects in range-independent oceanic waveguides. One of the main obstacles in the efficient use of tomographic imaging is that tomographic systems usually allow for a number of different independent solutions which satisfy the same systems of equations. This adverse property of acoustic tomography is especially pronounced in underdetermined systems characterized by null spaces of tomographic matrices which relate measured data to an unknown sound-speed distribution. In fact, acoustic tomography is usually underdetermined and the null space problem becomes critical in many applications. Acoustic tomography in many instances yields blurred images precluding its efficient use for mapping underwater objects in oceanic waveguides. How to improve the resolving power of tomographic imagery in waveguides is shown. A new technique based on the sliding window approach is suggested which uses constrained traveltime inversion. The method will be tested on mapping opaque and low-contrast acoustic objects placed in range-independent waveguides. The method is fast since it does not directly invert tomographic matrices of large rank but instead carries out summation over nonzero elements of tomographic matrices. It can be proved that constrained inversion compensates for limited angular aperture recording and thus can be applied to practical problems with incomplete angular aperture. This work is limited to processing of transmitted signals. A separate study will be devoted to the analysis of reflection data.

Acoustics↗
PubMed1991

Doxycycline tolerance study. Incidence of nausea after doxycycline administration to healthy volunteers: a comparison of 2 formulations (Doryx' vs Vibramycin').

In a randomised, double-blind, 3-way cross-over trial, the incidence of nausea associated with 2 doxycycline 100 mg formulations (Doryx' and Vibramycin') were compared. The original study cohort comprised 103 healthy male volunteers, with 97 subjects completing the trial. Subjects were randomly allocated to 1 of 3 treatment sequences and received a single dose of Doryx', Vibramycin' or placebo, with a 7-day washout prior to cross-over. At half-hourly intervals, from 0 to 2 h post-dose, subjects completed questionnaires to indicate if they felt nauseous. Data were analysed according to a log-linear method for the analysis of cross-over trials with categorical responses. Seventeen, 29 and 11 subjects experienced nausea with Doryx', Vibramycin' and placebo, respectively. A significantly greater number of volunteers indicated a positive response with Vibramycin' vs Doryx' and vs placebo; the positive response frequency was not significantly different for the Doryx' vs the placebo regimen. Treatment sequence had no significant effect on response, although a marked first-dose effect was noted; the first (vs the second and vs the third) regimen was 1.5-2 times more likely to induce a positive response.

Adult↗
PubMed1991

Activities of lipase and trypsin in duodenal juice of infants small for gestational age.

In 18 low birth weight infants, small for gestational age, with different degrees of intrauterine growth retardation the activities of pancreatic lipase and trypsin and the concentrations of bile acids were measured in preprandially aspirated duodenal juice. The results were compared to those of 24 low birth weight infants, appropriate for gestational age, with comparable birth weights and postnatal ages. The activities of both measured pancreatic enzymes were negatively correlated with the degree of intrauterine growth retardation, expressed as the difference between the individual birth weight and the weight of the 10th percentile of the intrauterine growth curve (lipase: r = -0.697, p less than 0.001; trypsin: r = -0.739, p less than 0.001). The activity of trypsin in the small for gestational age infants was within the range of that found in the infants appropriate for gestational age. However, the lipase activity was decreased in infants who presented with growth retardation of greater than 400 g/kg birthweight. The concentrations of bile acids were similar in both groups (4.60 +/- 2.51 and 4.55 +/- 2.26 mmol/L, respectively) and sufficient for activating the bile salt stimulated lipase in human milk. The data suggest that in intrauterine growth retarded infants the lipase activity in the duodenal juice can be a limiting factor for optimal fat digestion. This should be considered in the nutritional management of such infants.

Duodenum↗
PubMed1991

Effects of two antibiotics on hepatic function in low birth weight infants: ampicillin vs. cefotaxime.

In 21 low birth weight infants with two regimens of antibiotic therapy during the first 3 days of life possible hepatotoxic side effects were studied 8 days after the last administration of the tested drugs. Fourteen of the infants were treated with ampicillin/gentamicin and 7 received cefotaxime/gentamicin. The serum concentrations of total bile acids, the activities of transaminases in serum and the cumulative 15N excretion in urine after administration of 3 mg of 15N-labeled methacetin/kg of body weight were used as markers of hepatotoxic side effects. Neither the concentrations of total bile acids (22.6 +/- 12.1 and 19.4 +/- 10.8 mM, respectively) nor the activities of transaminases (alanine aminotransferase, 0.27 +/- 0.06 vs. 0.30 +/- 0.09 mumol/second/liter; aspartate aminotransferase, 0.46 +/- 0.11 vs. 0.49 +/- 0.10 mumol/second/liter) were different between the two groups. In contrast the cumulative 15N excretion in urine was significantly lower in the group treated with cefotaxime/gentamicin than in the group treated with ampicillin/gentamicin (17.2 +/- 6.4 vs. 33.0 +/- 5.1% of intake; P less than 0.01) and also lower than the reported age-related reference values. On the 28th day of life no differences could be found between the cumulative 15N excretion in the urine of the infants treated with cefotaxime/gentamicin and the reported age-related reference values of this test. The results indicate a limited capacity of the monooxygenase system of the liver of low birth weight infants during the first weeks of life and a specific reversible influence of cefotaxime on this hepatocellular system. Further investigations are required to evaluate the clinical relevance of this drug-specific inhibition of the hepatic monooxygenase pathway.

Acetamides↗
PubMed1991

Development of urea-synthesizing capacity in preterm infants during the first weeks of life.

The urea-synthesizing capacity of the liver was studied in 20 healthy preterm infants during the first month of life. The urea-synthesizing capacity was estimated by the ratio of 15N abundances of ammonia and urea in the 6-hour urine after administration of 3 mg 15N-labelled ammonium chloride/kg body weight. The ratio increases with increasing protein intakes from the 2nd to the 3rd week of life. On protein intakes of more than 3 g/kg/protein day from the 3rd week to the end of the 2nd month of life, the ratio decreases suggesting a maturation of the urea cycle during the first weeks of life.

Age Factors↗
PubMed1991

[Neonatal nutrition with enriched human milk. EOPROTIN 60 in comparison with human albumin].

The influence of feeding fresh human milk supplemented either with EOPROTIN (n = 13) or human albumin (n = 15) on biochemical parameters and growth were studied in preterm infants with gestational ages below 32 weeks p.m. up to the 42nd day of postnatal life. In both feeding groups the intakes of protein, energy and electrolytes were similar. The serum concentrations of bile acids, alpha-amino-nitrogen and prealbumin, the renal excretion of total nitrogen, alpha-amino-nitrogen, urea and ammonia as well as the growth in weight and length were studied in all infants. The supplementation of the fresh human milk with EOPROTIN results in significant lower serum concentrations of alpha-amino-nitrogen (1.56 +/- 0.21 vs 2.03 +/- 0.27 mmol/l; p less than 0.01), higher serum concentrations of prealbumin (89.8 +/- 20.3 vs 72.7 +/- 13.3 mg/l; p less than 0.02), and lower urinary excretion of total nitrogen (7.4 +/- 0.9 vs 8.9 +/- 1.1 mmol/kg/day); if compared to the results found in the infants fed human albumin supplemented human milk. The higher nitrogen retention in the EOPROTIN than in the human albumin fed infants was associated by a significant higher growth in weight (16.6 +/- 1.4 vs 13.7 +/- 1.9 g/kg/day; p less than 0.01) as well as in length (1.02 +/- 0.08 vs 0.87 +/- 0.1 cm/week; p less than 0.01). The results indicate that the bioavailability of EOPROTIN is higher than that of human albumin. The observed differences in the nutritional response between the two human milk supplements may be based on differences in the amino acids composition which is in EOPROTIN adapted to the nutritional available part of the protein in human milk.

Albumins↗
PubMed1991

Influence of casein feeding to very-low-birth weight infants on the plasma amino acid concentrations and the renal amino acid excretion.

The response of plasma and urine amino acid concentrations to a casein formula and to supplemented human milk (both 1.4 gm protein/100 ml) was measured in very-low-birth weight (VLBW) infants (less than 1500 gm) at a postconceptional age of 36 and 40 weeks, respectively. A control group of infants was fed exclusively with fresh human milk (HM). Casein feeding to VLBW infants resulted in prefeeding plasma amino acid profiles and renal amino acid excretions which were not markedly different from those found in infants fed supplemented HM. In comparison with the control feeding group, the infants fed casein or supplemented HM responded with higher total plasma amino acid concentrations (114.4 +/- 33.7 vs 171.0 +/- 36.1 or 167.1 +/- 27.1 mumol/100 ml, respectively) reflecting the higher amount of protein provided by these two feedings. The critical amino acids (sulfur-containing and aromatic amino acids) were metabolized efficiently in infants fed the casein formula. Furthermore, a highly significant relationship (r = 0.795; p less than 0.001) between the plasma concentrations of tyrosine and valine was achieved in all infants independent of the food applied. This relationship could represent a control mechanism to prevent an inordinate influx of aromatic amino acids into the brain. In VLBW infants at a postconceptional age of 36-40 weeks, the metabolic and functional maturity reaches levels which were similar to those found in term newborns.

Aging↗
PubMed1991

Postnatal development of urea- and ammonia-excretion in urine of very-low-birth-weight infants small for gestational age.

In 12 very-low-birth-weight (VLBW) infants with intrauterine growth retardation and in 14 VLBW-infants appropriate for gestational age (AGA) fed a human milk (HM) formula (HM enriched with 6 g freeze dried HM per 100 ml) the renal excretion of urea and ammonia was studied on the 10th, 21st and 42nd days of life. The lowest excretion of urea was found in both groups on the 10th day of life. Up to the 42nd day of life the excretion raised significantly more in the AGA- than in the small for gestational age (SGA)-infants. In contrast to the urea excretion the excretion of ammonia was highest on the 10th day of life in both groups, but the excretion was significantly higher in the SGA-infants if compared to the AGA-infants. In the AGA-infants excretion of ammonia decreased with postnatal age whereas in the SGA-infants the high excretion remained up to the 42nd day of life. The data suggest that in VLBW-infants the urea synthesizing capacity is decreased and develops within the first weeks of postnatal life. The postnatal development is delayed in SGA-infants when compared to AGA-infants. The differences are more pronounced with increasing degree of intrauterine growth retardation.

Ammonia↗
PubMed1991

[Early results of coronary surgery in patients between 71 and 80 years of age].

One hundred consecutive patients aged 71 to 80 without other cardiac pathology underwent coronary bypass surgery by the same surgical team between January 1986 and May 1989. These patients were recruited from a group of 687 patients undergoing coronary bypass surgery in the same period. The indication was always based on the severity of clinical symptoms resistant to medical therapy. Recent unstable angina despite triple therapy was a particularly common indication in this group of patients (61%). Preoperative coronary angiography showed a high incidence of triple vessel (62 cases) and left main stem disease (23 cases). Double vessel (12 cases) and single vessel disease (3 cases) were less common. Preoperative myocardial infarction was observed in 35% of cases; the site was nearly always on the inferior wall. In all, 230 bypasses were performed including 23 internal mammary artery bypasses (average 2.3 bypasses per patient). Six patients developed perioperative myocardial infarction confirmed by ECG and a rise in cardiac enzymes in 4 cases and by a rise in the cardiac enzymes alone in 2 cases. The mortality was low in this group of patients (3%). This was due to strict selection of patients in this age group and also to the improvement in the techniques of myocardial protection, anaesthesia and intensive care. Our results justify the operative indications in this group of patients in whom medical therapy has failed.

Age Factors↗
PubMed1990

Absorption of doxycycline from a controlled release pellet formulation: the influence of food on bioavailability.

A three-way crossover study was performed to compare the bioavailability of a new pelletised doxycycline product administered either with food or without food and a reference product taken without food. Four different methods were used to calculate pharmacokinetic parameters from the data. The sums of squares, Akaike's Information Criterion (AIC), and the ranges for the parameters obtained were used for comparison. Good fits to the data were obtained when all four methods were used, each with a lag time. The two compartment open model was the most efficient method for describing the data. The one compartment open model was the least efficient, particularly with respect to predicting the peak concentration of doxycycline in plasma. All the models gave similar rank order results with respect to bioavailability differences between the three treatments. Analysis of the data by different methods suggests that pelletised doxycycline is bioequivalent to the reference product when taken in the absence of food. A standardized feeding regimen affected the rate, but not extent of absorption of doxycycline from the pelletised formulation.

Absorption↗
PubMed1990

Bioavailability of a new sustained-release theophylline capsule in fasted and non-fasted healthy subjects: single and multiple dosing studies.

Eighteen healthy, non-smoking, adult volunteers participated in single and multiple dose three-way crossover studies to evaluate a sustained-release, pellet-filled capsule of theophylline, Austyn. The effect of food on the bioavailability of the sustained-release capsule was investigated by administering 300 mg single doses of Austyn, with a high-fat meal and without food and a divided 300 mg dose of the reference product Elixophyllin elixir, given after fasting. Plasma theophylline concentrations were measured by fluorescence polarization immunoassay (FPIA) which had been validated against HPLC. The single dose study data showed that there were no significant differences (n = 18, ANOVA, p greater than 0.05) between the three regimens with respect to AUC0-infinity values (mg h l-1), (mean +/- SD); Elixophyllin fasting = 97.1 +/- 33.7, Austyn with food = 90.9 +/- 31.3, Austyn fasting = 91.2 +/- 33.8. Similarly, multiple dosing with rapid-release Nuelin tablets, Austyn capsules, and sustained-release Theo-Dur tablets demonstrated that there were no significant differences between regimens with respect to AUC0-24h, AUC0-12h, and AUC12-24h values calculated from the steady-state concentrations (5th day, 24 h sampling). However, the percentage fluctuation at steady-state over the total blood sampling period was significantly less for treatment with the sustained-release capsule. Austyn, compared with the sustained-release tablet, Theo-Dur (Austyn = 36.7 +/- 13.7 per cent, Theo-Dur = 53.1 +/- 14.1 per cent). The results of the single and multiple dose studies indicate that Austyn capsules demonstrate complete bioavailability, and good controlled release characteristics not influenced by concomitant intake of a high-fat meal and with no evidence of dose dumping.

Adult↗
PubMed1990

[15N]methacetin urine test: a method to study the development of hepatic detoxification capacity.

The [15N]methacetin urine test was used to study human O-demethylase activities to characterize the maturation of hepatic detoxification capacity. The study involved 43 healthy subjects aged 1 day-47 years. The urinary 15N elimination rates were measured following oral administrations of an aqueous [15N]methacetin solution. Age-dependent normal values of hepatic drug elimination capacity were established. Parameters were the 15N elimination half-life and cumulative elimination of the 15N dose as a percentage over a 9 h period. The maximum elimination rate (% dose/h) and peak time can give additional information. The 15N method is a simple, non-invasive and non-radioactive liver function test avoiding disadvantages of 14C and 13C breath tests. The [15N]methacetin test is suitable and useful in studying the hepatic development at birth and pathological changes of the microsomal detoxification capacity in early childhood.

Acetamides↗
PubMed1990

Influence of intrauterine growth retardation on parameters of liver function in low birth weight infants.

To establish nutritional management of low birth-weight infants according to their individual metabolic situation, hepatocellular partial function was studied in 13 appropriate (AGA) and 11 small-for-gestational-age (SGA) low birthweight (LBW) infants during the first weeks of postnatal life. The concentrations of total bile acids and of alpha-amino-nitrogen in serum, the renal excretion of urea and ammonia and the renal excretion of 15N after enteral administration of 3 mg 15N-labeled methacetin/kg were measured. In comparison to AGA infants, SGA infants had elevated serum concentrations of total bile acids and of alpha-amino-nitrogen, decreased excretion of urea, increased excretion of ammonia in urine, and lower urinary 15N-excretion after enteral administration of 15N-labeled methacetin. The data suggest that hepatocellular functions are influenced by intrauterine growth retardation resulting in a reduced metabolic capacity in SGA infants. The metabolic differences between SGA and AGA infants should be considered in the nutritional management of LBW infants.

Acetamides↗
PubMed1990

Influence of postnatal age on nitrogen metabolism in very low birth weight infants appropriate for gestational age.

In 14 very low birth weight (VLBW) infants appropriate for gestational age the absorption and retention of nitrogen and the energy balance were studied on the 8th day and the 6th week of postnatal age. All infants were fed with a human milk formula composed by fresh mother's milk enriched with 6 g freeze-dried human milk/100 ml. The absorption rates of nitrogen and fat increase significantly with postnatal age but even on the 8th day of life they are on high levels (nitrogen absorption: 86.9 +/- 3.2% of intake; fat absorption: 85.7 +/- 4.3% of intake). Despite the higher nitrogen absorption during the 6th week of life the excretion of total nitrogen is lower in comparison to the 8th day of life. Similarly, the percentages of alpha-amino-nitrogen and of ammonium-nitrogen of the total nitrogen excretion in the urine decrease whereas the percentage of urea-nitrogen increases with postnatal age. The results indicate a postnatal development of both the digestive, as well as the metabolic capacity. The postnatal adaptation of the metabolic capacity to utilize nitrogen seems to be the stronger limiting factor for nutrition than the functional capacity of digestion and absorption. Thus, metabolic monitoring is essential for the individual nutrition of VLBW-infants during the first weeks of postnatal life. Urine analysis data are very sensitive for evaluating the metabolic state of these infants.

Aging↗
PubMed1990

[Consequences of the composition of human milk for the nutrition of low-birth-weight neonates. III. Sodium and potassium].

The concentrations of sodium and potassium were studied in the 24 hour pooled human milk of 37 mothers delivered preterm (PTM) and of 19 mothers delivered at term (TM) from the second to the eighth postnatal day and in addition in the PTM during the third week of lactation. During the 4th week of life the sodium balance was estimated in 31 very low birth weight infants fed a human milk formula enriched with NaCl (n = 11) or NaH2PO4 (n = 11) and in 9 infants fed the same formula without supplementary sodium. The concentrations of sodium decrease significantly during the first week of lactation. The values are significantly higher in PTM than in TM during the first 3 days but decrease in both milks to values between 1 and 2 mmol/100 ml. The concentrations of potassium increase up to the 4th day of lactation and fall to approximately 1.5 mmol/100 ml at the end of the first week of lactation. There are no differences between PTM and TM. In all three balance groups the sodium balance are positive. But only in the infants fed a sodium-supplemented human milk formula the weight gain was adequate according to the protein and caloric intakes. No signs of a pathological sodium retention could be observed during the balance period. The data suggest that a sodium intake of more than 2.5 mmol/kg/day is necessary for optimal growth. Thus, the phosphorus supplementation should be done generally as 1 mmol NaH2PO4/100 ml human milk in very low birth weight infants.

Energy Intake↗