[Post-conceptional age. Effect on protein requirements of premature infants]

In 12 preterm infants (mean gestational age: 28.9 weeks; mean birthweight: 1230 g) (Group 1) the serum concentrations of urea and alpha-amino-nitrogen were studied during the 32nd and between the 36th and 37th week of post-conceptional age. In 9 preterm infants with a mean gestational age of 34.6 weeks (mean birthweight: 1860 g) (Group 2) the same parameters were estimated during the 36th or 37th week of postconceptional age. In all male infants (group 1: n = 6; group 2: n = 5) the excretion of nitrogen in urine and stools were measured during a 48 h balance period. During the study all infants were fed with human milk enriched with 3 g of a bovine human milk fortifier (Eoprotin, Milupa AG, Germany) per 100 ml human milk (mean protein intake: 3.4 g/kg.day; mean caloric intake: 132.5 kcal/kg.day). Despite the similar protein and energy intakes on all study days the serum concentrations of urea and alpha-amino-nitrogen were significantly higher during the 36th or 37th postconceptional week if compared to those found during the 32nd postconceptional week. This was accompanied by elevated renal excretion of total nitrogen due to an increased excretion of urea in the older infants. The nitrogen excretions in stools were low during both study periods. During the period 36 and 37 weeks of postconceptional age no differences could be found for all parameters studied between the both groups of different gestational ages. The data of the present study suggest that in preterm infants with postconceptional age of 37 weeks or more protein intakes of 3.4 g/kg.day and more may exceed the requirements of these infants. Thus, supplementation of human milk with protein is not necessary after the 37th week of postconceptional age if feeding volumes of 170 ml/kg.day or more are tolerated.

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.

Altered flavin patterns in photobehavioral mutants of Phycomyces blakesleeanus

Flavins were extracted from sporangiophores of the lower fungus Phycomyces blakesleeanus and identified by HPLC with fluorescence detection. In the wild-type strain NRRL1555 they were found to be present at the following concentrations: riboflavin (5.5 x 10(-6) M), flavin mononucleotide (FMN) (4.0 x 10(-6) M) and flavin adenine dinucleotide (1.4 x 10(-6) M). The HPLC elution profiles of the wild type were compared to a set of behavioral mutants (genotype mad) with specific defects in their light-transduction pathway. The photoreceptor mutants C109 (madB), C111 (madB) and L1 (madC) had normal amounts of flavins. The most prominent changes were found in single mutants with a defective madA gene which contained about 25% of riboflavin and about 10% of FMN and FAD normally found in the wild type. A hypertropic mutant with a defective madH gene contained instead 80% of riboflavin and 120% of FMN and FAD. The double mutant L52 (madA madC) and the triple mutant L72 (madA madB madC) had normal amounts of FAD and FMN. This indicates that the madC mutation, which itself causes loss of light sensitivity and which affects the near-UV/blue-light receptor (Galland and Lipson, 1985, Photochem. Photobiol. 41, 331-335) functions as a restorer of the flavin content in a genetic madA background. The double mutant L51 (madA madB) had about 40% of FMN and FAD, suggesting that the madB mutation functions as a partial restorer of flavin content. The photogravitropic thresholds (450 nm) reported for the wild type and the madA and madH mutants were positively correlated to the endogeneous concentrations of FMN and FAD.(ABSTRACT TRUNCATED AT 250 WORDS)

Altered pterin patterns in photobehavioral mutants of Phycomyces blakesleeanus

Pterins were extracted with methanol from sporangiophores of the lower fungus Phycomyces blakesleeanus and separated and identified by high performance liquid chromatography (HPLC) with fluorescence detection. The following pterins were found and identified for the wild-type strain NRRL1555: carboxypterin (6.7 x 10(-6) M), neopterin (4.2 x 10(-7) M), xanthopterin (5.3 x 10(-6) M), biopterin (3.9 x 10(-7) M), pterin (9.1 x 10(-7) M), and 6,7-dimethylpterin (1.2 x 10(-6) M). The HPLC elution profiles of the wild type were compared to a set of phototropism mutants (genotype mad) with specific defects in the light-transduction pathway. The mutant profiles were qualitatively similar to those of the wild type. Quantitative differences were, however, discerned for madA, madC, and madH mutants. The madA mutation was associated with increased amounts of biopterin and 6,7-dimethylpterin and a reduction of neopterin, pterin, xanthopterin, and unidentified pterins eluting at 14-18 min. The stimulatory effect of the madA mutation on biopterin and 6,7-dimethylpterin appears to be compensated by a secondary mutation (pde) which is responsible for the loss of 75% of adenosine 3',5'-cyclic monophosphate (cAMP)-phosphodiesterase activity. In a madA pde double mutant the amounts of biopterin and 6,7-dimethylpterin fell below the wild-type level. These results suggest that an increased level of endogenous cAMP represses the biosynthesis of these pterins. The madC mutation increased the amounts of biopterin and xanthopterin and that of the unidentified pterins which could be derivatized to carboxypterin. Single madB mutations had, compared to the wild type, two times higher amounts of biopterin and two times lower amounts of neopterin.(ABSTRACT TRUNCATED AT 250 WORDS)

Antagonistic blue- and red-light regulation of cab-gene expression during photosynthetic adaptation in Scenedesmus obliquus

During adaptation of the photosynthetic apparatus of the green alga Scenedesmus obliquus to various light qualities, the accumulation of chlorophylls and pigment-protein complexes (with specific consideration of chlorophyll a/b-binding (Cab) proteins) and cab-gene expression were determined. The fluence rate dependences for chlorophyll accumulation and cab-gene expression were very different. Very low fluence rates of violet (404 nm), blue (461 nm) and red (650 nm) light below the photosynthetic threshold, i.e. between 10(-3) and 10(-1) mumol m-2 s-1, inhibited all of these reactions in cells grown under heterotrophic conditions. At elevated fluence rates (above 1 mumol m-2 s-1), red light retained its negative regulation, whereas blue light stimulated pigment accumulation. Under autotrophic conditions the pattern was more complex, because chlorophyll accumulation was unaffected by light below the photosynthetic threshold. However, the expression of cab-genes was inhibited by red light but stimulated by blue light. Cells adapted to fluence rates, which ensured photosynthetic energy supply (above 1 mumol m-2 s-1), showed an increase in chlorophyll accumulation, blue light being more effective than red light. The results confirm and extend our previous discovery of two antagonistically acting photoreceptors in Scenedesmus which mediate and coordinate the complex functional and structural changes associated with photosynthetic adaptation. One of these receptor pigments is a blue-light receptor with positive action; the other is a violet-red-light receptor which can operate far below the photosynthetic threshold and exerts a negative regulation.

[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.

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.

Riboflavin-binding sites associated with flagella of Euglena: A candidate for blue-light photoreceptor?

The hypothesis was tested that reversible riboflavin (RF)-binding sites are part of the photoreceptor in Euglena gracilis. Published evidence shows that the phototactic stimulus - with a flavin-type action spectrum - is perceived at the paraflagellar body (PFB). Flagella with PFBs were isolated from Euglena gracilis by a combined cold and Ca(2+) shock. Saturable binding of [(14)C]RF was demonstrated with such preparations, in the oxidized state as well as under reducing conditions in the presence of dithionite. Affinities for RF were high: K D (oxidized)=0.08 μM, and K D (reduced)=0.7 μM. Flavin mononucleotide and flavin adenine dinucleotide showed lower binding affinities. The in vitro RF binding per unit of protein was enriched approximately tenfold in the flagellar preparations when compared with homogenates of whole cells. The number of (reduced) binding sites per entire flagellum was determined to be in the order of 10(6). This number is in line with published estimates of chromophores bound in or at the PFB.

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.

Action spectra for photosynthetic adaptation in Scenedesmus obliquus : I. Chlorophyll biosynthesis under autotrophic conditions

Photosynthetic adaptation of the unicellular green alga Scenedemus obliquus to different light conditions was investigated with respect to chlorophyll synthesis. Cultures were grown under white light (20 W · m(-2)) from fluorescent lamps and were then transferred and subjected to the actual adaptation regime which consisted of a 24-h irradiation by different fluence rates and wavelengths. Fluence rate-response curves for chlorophyll synthesis were measured between 4 · 10(-2) and 1 · 10(2) W · m(-2). In white light from incandescent lamps, in blue and red light the fluence rate-response curves for chlorophyll (Chl) a and also for Chl b were bell-shaped. In red light the threshold was about the same as under blue light. The maximal amounts of Chl a and b were about twofold increased under blue light relative to the values obtained with red light. Action spectra for the stimulation of chlorophyll synthesis (Chl a + Chl b) as well as those for the separate chlorophylls showed two maxima near 450 and 500 nm. However, the action spectrum for Chl b synthesis demonstrated a considerably higher value in the 450-nm peak. Experiments with the photosynthesis inhibitor 3-(3,4-dichlorphenyl)-1,1-dimethylurea (DCMU) indicated that photosynthetic energy supply supported the photostimulation of chlorophyll synthesis. The action spectra indicate the cooperation of two photoreceptors. The 460-nm peak is attributed to the "typical" blue-light receptor, being more active in Chl b formation. The peak at 500 nm may represent carotenoproteins acting as an accessory pigment system.

Microspectrophotometry ofEuglena gracilis : Pterin- and flavin-like fluorescence in the paraflagellar body

The paraflagellar bodies (PFBs) of isolated flagella ofEuglena gracilis were investigated microspectrophotometrically using a visible- and infrared-light microscope with image analyzer and microspectrophotometer. Flagella with attached PFBs were separated from the cell bodies by a short exposure to near-UV light. Fluorescence-emission spectra (excitation at 365 nm) of single PFBs had maxima near 470 and 520 nm, indicating the presence of pterins and flavins. No fluorescence was associated with the flagella themselves. Pterin- and flavin-like fluorescence emission was also found in blue-fluorescing vesicles distributed throughout the entire cell body ofEuglena. Their characterization by microfluorimetry was greatly aided by the use of chlorophyll-free mutants in which the signal-to-noise ratio was distinctly enhanced because of the lack of chlorophyll fluorescence. Our finding of flavin-like fluorescence associated with PFB strengthens similar earlier reports in the literature. The occurrence of pterin-like fluorescence in the PFB lends further support to our earlier proposal that pterins as well as flavins may function as photoreceptor pigments for near-UV and blue light.

Relationship between biosynthesis of carotenoids and increasing complexity of photosystem I in mutant C-6D of Scenedesmus obtiquus

Dark-grown cells of the pigment mutant C-6D of Scenedesmus obliquus, strain D3 (Gaffron 1939), contain only chlorophyll (Chl) a and carotenoid precursors. In these cells a functioning photosystem I (PSI) of basic structure was characterised by a high PSI activity and a low Chl/P700 ratio. The reaction-center complex of PSI (CPI) was shown to exist in the dark-grown cells. These findings demonstrate that the assembly of the core complex of PSI and its function are independent of the presence of carotenoids. Upon illumination, carotenoids, Ch1 b and additional Chl a were synthesized. Newly formed β-carotene was shown by pigment analysis using high-performance liquid chromatography (HPLC) to be incorporated into CPI. Parallel to this process a shift of the long-wavelength fluorescence emission of PSI from 712-714 to 718-719 nm was observed. In the later stages of chloroplast differentiation, when xanthophylls and Chl b were synthesized, a higher-molecular-weight complex of PSI (CPIa) could be isolated. Pigment analysis demonstrated that CPIa contained xanthophylls and Chl b in addition to Chl a and β-carotene. This indicates the formation of a light-harvesting antenna closely associated with PSI (LHCI). The addition of an LHCI to the reaction-center complex of PSI caused an increase in the absorption cross-section of PSI as shown by action spectroscopy and in-vivo fluorescence measurements. A model demonstrating the changes in the molecular organization of PSI during light-induced carotenoid biosynthesis in mutant C-6D of Scenedesmus obliquus is presented.

Protein supplementation of human milk for the nutrition of VLBW-infants: human milk protein vs. meat protein hydrolysate

In 25 very low birth weight infants appropriate for gestational age the influences of different human milk (HM) preparations on weight gain, gross indices of nitrogen metabolism and energy balance were studied during the second month of postnatal life. HM was fortified either by HM-protein (HMP) or by an enzymatic meat protein hydrolysate (PH) to protein concentrations between 1.5 and 1.7 g/100 ml. The caloric densities of both HM preparations were similar between 62 and 68 kcal/100 ml. There were no differences in weight gain (MM + HMP: 18.6 +/- 3.4 g/kg/day; HM + PH: 16.5 +/- 4.1 g/kg/day), nitrogen retention (HM + HMP: 31.5 +/- 3.1 mmol/kg/day; HM + PH: 30.0 +/- 3.2 mmol/kg/day), and the preprandial estimated essential amino acid profiles between the both feeding groups. In contrast the serum concentrations of alpha-amino-nitrogen 60 minutes postprandially were elevated in the infants fed HM + PH in comparison to the infants fed HM + HMP. This high postprandial amino acid concentrations in serum in the group fed HM + PH were accompanied by increased bile acids concentrations in serum, higher renal amino acid excretion and increased fecal fat losses. The results suggest that due to the more rapid intestinal absorption of amino acids from PH than from HMP the concentrations of amino acids increase postprandially which results in a detectable increase of the newborn cholestasis in these infants. Nevertheless, the scale of these metabolic responses to feeding protein hydrolysates is small and without detectable influences on nitrogen retention or weight gain.

Two Systems for Concentrating CO(2) and Bicarbonate during Photosynthesis by Scenedesmus

Scenedesmus cells grown on high CO(2), when adapted to air levels of CO(2) for 4 to 6 hours in the light, formed two concentrating processes for dissolved inorganic carbon: one for utilizing CO(2) from medium of pH 5 to 8 and one for bicarbonate accumulation from medium of pH 7 to 11. Similar results were obtained with assays by photosynthetic O(2) evolution or by accumulation of dissolved inorganic carbon inside the cells. The CO(2) pump with K(0.5) for O(2) evolution of less than 5 micromolar CO(2) was similar to that previously studied with other green algae such as Chlamydomonas and was accompanied by plasmalemma carbonic anhydrase formation. The HCO(3) (-) concentrating process between pH 8 to 10 lowered the K(0.5) (DIC) from 7300 micromolar HCO(3) (-) in high CO(2) grown Scenedesmus to 10 micromolar in air-adapted cells. The HCO(3) (-) pump was inhibited by vanadate (K(i) of 150 micromolar), as if it involved an ATPase linked HCO(3) (-) transporter. The CO(2) pump was formed on low CO(2) by high-CO(2) grown cells in growth medium within 4 to 6 hours in the light. The alkaline HCO(3) (-) pump was partially activated on low CO(2) within 2 hours in the light or after 8 hours in the dark. Full activation of the HCO(3) (-) pump at pH 9 had requirements similar to the activation of the CO(2) pump. Air-grown or air-adapted cells at pH 7.2 or 9 accumulated in one minute 1 to 2 millimolar inorganic carbon in the light or 0.44 millimolar in the dark from 150 micromolar in the media, whereas CO(2)-grown cells did not accumulate inorganic carbon. A general scheme for concentrating dissolved inorganic carbon by unicellular green algae utilizes a vanadate-sensitive transporter at the chloroplast envelope for the CO(2) pump and in some algae an additional vanadate-sensitive plasmalemma HCO(3) (-) transporter for a HCO(3) (-) pump.

[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)

Evidence for an essential role of carotenoids in the assembly of an active photosystem II

Dark-grown cells of mutant C-6D of the green alga Scenedesmus obliquus exhibit a high activity of photosystem I (PSI) but lack activity of photosystem II (PSII). These cells contain only the pigment-protein complex CPI, representing the reaction-center of PSI. Only chlorophyll a and precursors of carotenoids (lycopene, neurosporene, ξ-carotene, β-zeacarotene) could be detected in dark-grown cells by analysis using high-performance liquid chromatography.Activity of PSII and the corresponding pigment-protein complex, CPa, develop immediately upon transfer to light. Light-harvesting complexes and higher molecular forms of PSI are synthesized only in the later stages of light-induced chloroplast differentiation. During illumination the amounts of carotenoid precursors decrease and carotenes, xanthophylls and chlorophylls a and b are formed. β-Carotene and lutein are synthesized without a lag-phase. Their kinetics are similar to those of CPa formation and development of PSII activity. In contrast, all other xanthophylls are synthesized only after a lag-phase of about 30 min.Inhibition of the transformation of precursors into carotenoids by nicotine prevents the light-inducible development of PSII activity and CPa formation. During illumination under anaerobic conditions no xanthophylls are synthesized but high amounts of α- and β-carotene accumulate. Such cells exhibit no PSII activity and show only traces of CPa. After subsequent transfer to aerobic conditions the xanthophylls are synthesized and simultaneously active PSII units are formed.The results prove that carotenoids are essential components for the assembly of active PSII units. Strong evidence is given that lutein is the absolute necessary prerequisite for this process. Whether β-carotene is also an absolute necessary prerequisite for a functioning PSII unit cannot be deduced from our experiments.

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.

Different Porphobilinogenases in Cytoplasm and Isolated Chloroplasts from Light-Grown Euglena gracilis Z

Lysed cells as well as different fractions of isolated, disrupted chloroplasts from light grown Euglena gracilis were tested for their capability of porphyrin biosynthesis. It is shown that the formation of the soluble porphobilinogenase (PBG-ase) fraction is inhibited by cycloheximide indicating its biosyntheses on 80S ribosomes, whereas the formation of the membrane bound chloroplast PBG-ase is chloramphenicol sensitive. Different pH-optima are demonstrated for the two enzymes. From the presented results it is deduced from those isolated from dark grown cells.

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.

Influence of energy flux and quality of light on the molecular organization of the photosynthetic apparatus in Scenedesmus

The photosynthetic apparatus of the unicellular green alga Scenedesmus obliquus adapts to different levels and qualities of light as documented by the fluence-rate curves of photosynthetic oxygen evolution. Cultures adapted to low fluence rates of white light (5W·m(-2)) have more chlorophyll (Chl) per cell mass, a higher chlorophyll to carotenoid ratio and a doubling of the chlorophyll to cytochrome f ratio compared with cells adapted to high fluence rates of white light (20W·m(-2)). Only small differences can be observed in the halfrise time of fluorescence induction, the electrophoretic profile of the pigment-protein complexes and the Chl a/Chl b-ratio. Scenedesmus cells adapted to blue light of high spectral purity demonstrate, in comparison with those adapted to red light, a higher chlorophyll content, a higher ratio of chlorophyll to carotenoid and a much higher ratio of chlorophyll to cytochrome f. Regarding these parameters and the fluence-rate curves of photosynthesis, the blue light causes the same effects as low levels of white light. In contrast, the action of red light resembles rather that of high levels of white light. Blue-light-adapted Scenedesmus cells have a smaller Chl a to Chl b ratio, a faster half-rise time of fluorescence induction and more chlorophyll in the light-harvesting system than red-light-adapted cells, as shown in the electrophoretic profile of the pigment-protein complexes. Based on these results we propose a model for the adaptation of the photosynthetic apparatus of Scenedesmus to different levels and qualities of light. In this model low as compared with high levels of white light result in an increase in the number of photosystems per electron-transport chain, but not in an increase in the size of these photosystems. The same result is obtained by adaptation to blue light. The lack of sufficient Chl b formation in red-light-adapted cells results in a decrease in the light harvesting chlorophyll-protein complexes and a photosynthetic response like that found in cells adapted to high light levels. The findings reported here confirm our earlier results in comparing blue-and red-light adaptation of the photosynthetic apparatus with adaptation to low and high levels of white light, respectively.

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.

Ascorbic Acid and Glutathione Contents of Spruce Needles from Different Locations in Bavaria

Spruce Decline, Ascorbic Acid, Glutathione Green and bleached needles or needle segments were analyzed for their ascorbic acid and glutathione contents. All bleached needles or segments exhibited higher amounts of both sub­ stances as com pared to green controls.

The physiological significance of the increase in ascorbic acid and in glutathione is discussed in content with their roles as antioxidants.

Cholestasis in late metabolic acidosis of prematurely born infants

Serum concentrations of bile acids and tyrosine were determined in 14 premature infants with late metabolic acidosis and in 13 comparable controls without acidosis (protein intake 2 g/kg X d). At the same time the bile acids and the catalytic activity concentrations of lipase and trypsin were estimated in the duodenal juice. The daily faecal excretion and the percentage of fat eliminated were measured. In 8 patients with late metabolic acidosis the duodenal studies were repeated one week after late metabolic acidosis. Infants with late metabolic acidosis showed significantly higher concentrations of bile acids and tyrosine in the serum than the controls (p less than 0.0005). In the duodenal juice the activities of lipase and trypsin and the concentration of bile acids--especially of dihydroxy bile acids--were decreased (p less than 0.001). The faecal excretion during late metabolic acidosis was significantly increased, with high percentage of fat. Eight days after late metabolic acidosis all duodenal parameters equalled the range of the control group. The relations between acidosis, cholestasis, and amino acid transport to the liver are discussed.