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Biomedical subjects

G Boehm

Publications and source records attributed to G Boehm.

At least 73 records · Page 4Linked to original sources
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↗
PubMed1990

[Significance of environmental factors on the tolerated enteral feeding volumes for patients in neonatal intensive care units].

The influence of environmental factors on the tolerated feeding volumes as well as on the frequency of breathing were studied in 32 infants. During intensive neonatal care the tolerated feeding volumes were decreased and also the frequencies of breathing were influenced. The duration and intensity of light exposure was related as one of the most important factors.

Enteral Nutrition↗
PubMed1990

Postnatal adaptation of lipase- and trypsin-activities in duodenal juice of premature infants appropriate for gestational age.

In 17 very low birth weight and in 13 low birth weight infants appropriate for gestational age the activities of pancreatic lipase and trypsin, the pH value and the concentrations of total bile acids were measured in the preprandially aspirated duodenal juice between the 10th and the 40th day of postnatal life. The activities of both enzymes increased significantly with increasing postnatal age in both study groups but did not correlate with the gestational age between the 28th and 33rd week of gestation. The pH values were on a low but similar level in both study groups (mean for all infants 5.66 +/- 0.07), and there was no influence of the pH value on the activities of either pancreatic enzyme. The concentrations of total bile acids were also not different between the study groups (mean for all infants = 4.55 +/- 2.26 mmol/l) and no correlation could be found between the concentrations of total bile acids and the activities of both measured enzymes. The data suggest that the intrauterine development of the exocrine pancreas reaches a basal level by the 28th week of gestation and remains on this level up to the 33rd week of gestation. After birth there is a significant increase in enzyme activities for both studied enzymes.

Adaptation, Physiological↗
PubMed1990

Relationship between urea and ammonium excretion in the urine of very-low-birth-weight infants appropriate for gestational age.

In 14 very-low-birth-weight infants appropriate for gestational age the serum concentrations of urea and the excretions of urea and ammonium in the urine were studied on the 10th, 21st, and 42nd day of postnatal life. All infants were fed with a human milk preparation (6 g human milk lyophilisate per 100 ml fresh human milk). The enteral feeding could be started on the first day of life so that protein intakes were not different on the three study days (2.94 vs. 2.98 vs 3.13 g/kg.d). The renal excretion of urea increased significantly from the 10th to the 42nd day of life (1.2 +/- 0.13 vs 2.1 +/- 0.24 mmol/kg.d) whereas the excretion of ammonium decreased during the same time (0.53 +/- 0.06 vs 0.29 +/- 0.05 mmol/kg.d). There was a significantly negative correlation between the excretion of urea and of ammonia on all study days. The weight gain was sufficient for the given protein intakes (18.9 +/- 3.4 g/kg.d). The results indicate a transient limited capacity of the urea synthesizing system in the liver of very-low-birth-weight infants during the first weeks of life which should be considered if metabolic responses to protein intake are studied and evaluated in these infants.

Acid-Base Equilibrium↗
PubMed1989

Dihydrofolate reductase of the extremely halophilic archaebacterium Halobacterium volcanii. The enzyme and its coding gene.

Halobacterium volcanii mutants that are resistant to the dihydrofolate reductase inhibitor trimethoprim contain DNA sequence amplifications. This paper describes the cloning and nucleic acid sequencing of the amplified DNA sequence of the H. volcanii mutant WR215. This sequence contains an open reading frame that codes for an amino acid sequence that is homologous to the amino acid sequences of dihydrofolate reductases from different sources. As a result of the gene amplification, the trimethoprim-resistant mutant overproduces dihydrofolate reductase. This enzyme was purified to homogeneity using ammonium sulfate-mediated chromatographies. It is shown that the enzyme comprises 5% of the cell protein. The amino acid sequence of the first 15 amino acids of the enzyme fits the coding sequence of the gene. Preliminary biochemical characterization shows that the enzyme is unstable at salt concentrations lower than 2 M and that its activity increases with increase in the KCl or NaCl concentrations.

Amino Acid Sequence↗
PubMed1989

Metabolic differences between AGA-and SGA-infants of very low birthweight. III. Influence of postnatal age.

Seven very low birthweight (VLBW) infants, small for gestational age (SGA), with moderate intrauterine growth retardation and 7 VLBW-infants, appropriate for gestational age (AGA), fed breast milk fortified with 6 g freeze-dried human milk per 100 ml were studied on the 8th, 21st and 42nd days of life. The protein intake on the study days varied between 2.68 and 3.61 g/kg/day in the SGA-and 2.69 and 3.75 g/kg/day in the AGA-infants. Serum concentrations of total bile acids (BA) and the renal excretion of total nitrogen (TN) as well as alpha-amino-nitrogen (AAN) were measured in all infants on each study day. On the 8th day of life a mean protein intake of 3.2 g/kg/day resulted in higher serum concentrations of BA as well as in a higher renal excretion of TN and AAN in the SGA-infants when compared to the AGA-infants. On the 21st day of life these differences were smaller and only the serum concentration of BA and the renal excretion of AAN were still significantly higher in the SGA-infants. On the 42nd day of life only serum concentrations of total BA were elevated in the SGA-infants when compared to that in the AGA-infants. The observed metabolic differences between moderately SGA-and AGA-infants related to protein and bile acid metabolism diminished during the first weeks of life. The present data suggest that when nutritional management of VLBW-infants is planned, differences in metabolic capacities must be considered and protein intake should be increased with caution and in accordance to the individual metabolic situation of the infants during the first weeks of life.

Age Factors↗
PubMed1989

[Consequences of the composition of breast milk for the nutrition of underweight newborn infants. II. Lipids and lactose].

The concentrations of fat, lactose and protein were measured in the 24 hour pooled breast milk of 37 mothers delivering preterm (PTM) and of 19 mothers delivering term (TM) from the second to the eighth postnatal day and in addition in the PTM from the third week of lactation. During the 4th week of life the nitrogen retention, the fat absorption rate as well as the energy balance were estimated in 21 very low birth weight infants appropriate for gestational age fed either native PTM (n = 11) or by heating procedures sterilized PTM (n = 10). The concentrations of fat and lactose increase within in the first week of lactation. The concentrations of fat are higher in the PTM during the first 3 days of lactation which results in a higher energy density of PTM during the first days of lactation. At the end of the first week of lactation there are no differences in the energy density between PTM and TM. The fat absorption rate was significantly lower in the infants fed sterilized PTM than in the infants fed native PTM (70.5 +/- 8.4 vs 86.3 +/- 7.4 p.c.). Thus, an energy intake of (70.5 to 8.4 vs 86.3 +/- 7.4 p.c.). Thus, an energy intake of 120-130 kcal/kg.d or an energy absorption of more than 100 kcal/kg.d; respectively, is possible by feeding native PTM as well as TM when feeding volumes of more than 180 ml/kg.d are tolerated. When sterilized breast milk is used or the feeding volume is below 160 ml/kg.d an energy supplementation of the milk is necessary.(ABSTRACT TRUNCATED AT 250 WORDS)

Breast Feeding↗
PubMed1988

Metabolic differences between AGA- and SGA-infants of very low birthweight. I. Relationship to intrauterine growth retardation.

Metabolic response to human milk feeding was studied in 12 appropriate (AGA) and 12 small for gestational age (SGA) infants of very low birthweight (VLBW) on the eighth day of life. Protein intake ranged from 1.98 to 2.47 g/kg/day and caloric intake from 94 to 126 kcal/kg/day with no significant differences between the groups. Alpha-amino-nitrogen, the total bile acid concentration in serum and total- as well as alpha-amino-nitrogen excretion in the urine were estimated. The alpha-amino-nitrogen and the total bile acid concentration in serum increased with increasing degree of intrauterine growth retardation. Also renal total- and alpha-amino-nitrogen excretion increased significantly in relation to the degree of intrauterine growth retardation. Thus, despite a relatively low protein intake in severely growth retarded VLBW-infants, metabolic changes could be found similar to those observed in AGA-infants on high protein intakes. The data suggest that during the first weeks of postnatal life VLBW-infants with intrauterine growth retardation have a decreased capacity to utilize or to metabolize protein when compared to AGA-infants with comparable birthweights. These metabolic differences have to be considered in the nutritional management of VLBW-infants.

Dietary Proteins↗
PubMed1988

Metabolic differences between AGA- and SGA-infants of very low birthweight. II. Relationship to protein intake.

The metabolic response to different levels of human milk protein intake was studied in 23 appropriate (AGA) and 19 small for gestational age (SGA) infants of very low birthweight (VLBW) on the eighth day of life. The infants received from birth, either fresh preterm human milk or human milk fortified with lyophilized human milk (6 g per 100 ml). Thus, the protein intake ranged from 1.98 to 3.28 g/kg/d in the AGA- and from 1.94 to 3.34 g/kg/d in the SGA-infants. Alpha-amino-nitrogen and bile acid concentrations in serum and total- as well as alpha-amino-nitrogen excretion in the urine were measured. When the protein intake was less than 2.5 g/kg/d no differences between the groups could be found in any of the parameters directly related to nitrogen metabolism, but a significantly higher concentration of bile acids in serum was found in the SGA-infants. On protein intakes of more than 2.5 g/kg/d the SGA-infants responded with higher alpha-amino-nitrogen as well as total bile acids concentrations in the serum and also with higher excretions of total- as well as alpha-amino-nitrogen in the urine when compared to the AGA-infants. The differences between the groups became more pronounced with an increasing protein intake. The data suggest that on the eighth day of life SGA-infants are more sensitive to an excessive protein intake than AGA-infants. Hepatocellular dysfunctions as a result of intrauterine growth retardation seems to be an important factor in this special metabolic situation. Bile acid concentration in the serum can be used as a good marker to detect this. The observed differences in the metabolic capacity to handle protein between AGA- and SGA-infants on the eighth day of life have to be considered in the nutritional management of VLBW-infants.

Bile Acids and Salts↗
PubMed1988

Evidence for functional immaturity of the ornithine-urea cycle in very-low-birth-weight infants.

In a randomized, prospective study the response of serum urea concentration to different protein intakes was studied in two groups of preterm infants with different gestational ages on the 8th and the 21st day of life. 16 very-low-birth-weight (VLBW) infants (GA: 29-31 weeks) and 17 low-birth-weight (LBW) infants (GA: 31-33 weeks) were fed either with fresh human milk or with fortified human milk. The protein intake varied between 2.1 and 3.3 g/kg/day. On the 8th day of life the VLBW infants did not respond to higher protein intakes by increased serum urea concentrations, although a clear correlation was found between protein intake and serum alpha-amino-nitrogen concentrations in these infants. The more mature LBW infants responded to a high protein intake by increased serum urea concentrations on the 8th day of life. On the 21st day of life protein intake correlated to both serum urea and alpha-amino-nitrogen concentrations in all infants studied. These findings are consistent with a somewhat limited capacity of the immature infant for expansion of urea production for some time after birth. This immaturity should be considered when metabolic responses to protein intake are studied and evaluated in such infants.

Birth Weight↗