The Story of RNA Unfolded: The Molecular Function of DEAD- and DExH-Box ATPases and Their Complex Relationship with Membraneless Organelles

DEAD- and DExH-box ATPases (DDX/DHXs) are abundant and highly conserved cellular enzymes ubiquitously involved in RNA processing. By remodeling RNA-RNA and RNA-protein interactions, they often function as gatekeepers that control the progression of diverse RNA maturation steps. Intriguingly, most DDX/DHXs localize to membraneless organelles (MLOs) such as nucleoli, nuclear speckles, stress granules, or processing bodies. Recent findings suggest not only that localization to MLOs can promote interaction between DDX/DHXs and their targets but also that DDX/DHXs are key regulators of MLO formation and turnover through their condensation and ATPase activity.In this review, we describe the molecular function of DDX/DHXs in ribosome biogenesis, messenger RNA splicing, export, translation, and storage or decay as well as their association with prominent MLOs. We discuss how the enzymatic function of DDX/DHXs in RNA processing is linked to DDX/DHX condensation, the accumulation of ribonucleoprotein particles and MLO dynamics. Future research will reveal how these processes orchestrate the RNA life cycle in MLO space and DDX/DHX time.

Ribosome biogenesis factors-from names to functions

The assembly of ribosomal subunits is a highly orchestrated process that involves a huge cohort of accessory factors. Most eukaryotic ribosome biogenesis factors were first identified by genetic screens and proteomic approaches of pre-ribosomal particles in Saccharomyces cerevisiae. Later, research on human ribosome synthesis not only demonstrated that the requirement for many of these factors is conserved in evolution, but also revealed the involvement of additional players, reflecting a more complex assembly pathway in mammalian cells. Yet, it remained a challenge for the field to assign a function to many of the identified factors and to reveal their molecular mode of action. Over the past decade, structural, biochemical, and cellular studies have largely filled this gap in knowledge and led to a detailed understanding of the molecular role that many of the players have during the stepwise process of ribosome maturation. Such detailed knowledge of the function of ribosome biogenesis factors will be key to further understand and better treat diseases linked to disturbed ribosome assembly, including ribosomopathies, as well as different types of cancer.

Genome-wide RNAi screen identifies novel players in human 60S subunit biogenesis including key enzymes of polyamine metabolism

Ribosome assembly is an essential process that is linked to human congenital diseases and tumorigenesis. While great progress has been made in deciphering mechanisms governing ribosome biogenesis in eukaryotes, an inventory of factors that support ribosome synthesis in human cells is still missing, in particular regarding the maturation of the large 60S subunit. Here, we performed a genome-wide RNAi screen using an imaging-based, single cell assay to unravel the cellular machinery promoting 60S subunit assembly in human cells. Our screen identified a group of 310 high confidence factors. These highlight the conservation of the process across eukaryotes and reveal the intricate connectivity of 60S subunit maturation with other key cellular processes, including splicing, translation, protein degradation, chromatin organization and transcription. Intriguingly, we also identified a cluster of hits comprising metabolic enzymes of the polyamine synthesis pathway. We demonstrate that polyamines, which have long been used as buffer additives to support ribosome assembly in vitro, are required for 60S maturation in living cells. Perturbation of polyamine metabolism results in early defects in 60S but not 40S subunit maturation. Collectively, our data reveal a novel function for polyamines in living cells and provide a rich source for future studies on ribosome synthesis.

Processing of the ribosomal ubiquitin-like fusion protein FUBI-eS30/FAU is required for 40S maturation and depends on USP36

In humans and other holozoan organisms, the ribosomal protein eS30 is synthesized as a fusion protein with the ubiquitin-like protein FUBI. However, FUBI is not part of the mature 40S ribosomal subunit and cleaved off by an as-of-yet unidentified protease. How FUBI-eS30 processing is coordinated with 40S subunit maturation is unknown. To study the mechanism and importance of FUBI-eS30 processing, we expressed non-cleavable mutants in human cells, which affected late steps of cytoplasmic 40S maturation, including the maturation of 18S rRNA and recycling of late-acting ribosome biogenesis factors. Differential affinity purification of wild-type and non-cleavable FUBI-eS30 mutants identified the deubiquitinase USP36 as a candidate FUBI-eS30 processing enzyme. Depletion of USP36 by RNAi or CRISPRi indeed impaired FUBI-eS30 processing and moreover, purified USP36 cut FUBI-eS30 in vitro. Together, these data demonstrate the functional importance of FUBI-eS30 cleavage and identify USP36 as a novel protease involved in this process.

USP16 counteracts mono-ubiquitination of RPS27a and promotes maturation of the 40S ribosomal subunit

Establishment of translational competence represents a decisive cytoplasmic step in the biogenesis of 40S ribosomal subunits. This involves final 18S rRNA processing and release of residual biogenesis factors, including the protein kinase RIOK1. To identify novel proteins promoting the final maturation of human 40S subunits, we characterized pre-ribosomal subunits trapped on RIOK1 by mass spectrometry, and identified the deubiquitinase USP16 among the captured factors. We demonstrate that USP16 constitutes a component of late cytoplasmic pre-40S subunits that promotes the removal of ubiquitin from an internal lysine of ribosomal protein RPS27a/eS31. USP16 deletion leads to late 40S subunit maturation defects, manifesting in incomplete processing of 18S rRNA and retarded recycling of late-acting ribosome biogenesis factors, revealing an unexpected contribution of USP16 to the ultimate step of 40S synthesis. Finally, ubiquitination of RPS27a appears to depend on active translation, pointing at a potential connection between 40S maturation and protein synthesis.

A versatile liquid-jet setup for the European XFEL

The SPB/SFX instrument of the European XFEL provides unique possibilities for high-throughput serial femtosecond crystallography. This publication presents the liquid-jet sample delivery setup of this instrument. The setup is compatible with state-of-the-art gas dynamic virtual nozzle systems as well as high-viscosity extruders and provides space and flexibility for other liquid injection devices and future upgrades. The liquid jets are confined in a differentially pumped catcher assembly and can be replaced within a couple of minutes through a load-lock. A two-microscope imaging system allows visual control of the jets from two perspectives.

AXSIS: Exploring the frontiers in attosecond X-ray science, imaging and spectroscopy

X-ray crystallography is one of the main methods to determine atomic-resolution 3D images of the whole spectrum of molecules ranging from small inorganic clusters to large protein complexes consisting of hundred-thousands of atoms that constitute the macromolecular machinery of life. Life is not static, and unravelling the structure and dynamics of the most important reactions in chemistry and biology is essential to uncover their mechanism. Many of these reactions, including photosynthesis which drives our biosphere, are light induced and occur on ultrafast timescales. These have been studied with high time resolution primarily by optical spectroscopy, enabled by ultrafast laser technology, but they reduce the vast complexity of the process to a few reaction coordinates. In the AXSIS project at CFEL in Hamburg, funded by the European Research Council, we develop the new method of attosecond serial X-ray crystallography and spectroscopy, to give a full description of ultrafast processes atomically resolved in real space and on the electronic energy landscape, from co-measurement of X-ray and optical spectra, and X-ray diffraction. This technique will revolutionize our understanding of structure and function at the atomic and molecular level and thereby unravel fundamental processes in chemistry and biology like energy conversion processes. For that purpose, we develop a compact, fully coherent, THz-driven atto-second X-ray source based on coherent inverse Compton scattering off a free-electron crystal, to outrun radiation damage effects due to the necessary high X-ray irradiance required to acquire diffraction signals. This highly synergistic project starts from a completely clean slate rather than conforming to the specifications of a large free-electron laser (FEL) user facility, to optimize the entire instrumentation towards fundamental measurements of the mechanism of light absorption and excitation energy transfer. A multidisciplinary team formed by laser-, accelerator,- X-ray scientists as well as spectroscopists and biochemists optimizes X-ray pulse parameters, in tandem with sample delivery, crystal size, and advanced X-ray detectors. Ultimately, the new capability, attosecond serial X-ray crystallography and spectroscopy, will be applied to one of the most important problems in structural biology, which is to elucidate the dynamics of light reactions, electron transfer and protein structure in photosynthesis.

Die neue menschliche Seinsweise der Demenz

Today, for the first time in the history of mankind, the number of demented people is so large that we are compelled to speak of a particular population group and a characteristic human mode of being. Ten perspectives describe which personal and societal changes will enable us to adjust to this new situation. Particular consideration is given to a new, more complete image of man.

Molybdenum balance studies in premature male infants

Despite the fact that the trace element molybdenum (Mo) is essential, there is insufficient knowledge about the demands in infancy. Mo balances were therefore assessed under consideration of formula Mo concentrations ranging from 0.125 to 2.704 micromol/l. Sixteen premature male infants participated in the investigation. Their birth weights were between 1,500 and 1,990 g, the median (range) gestational age was 34 (32-36) weeks and the post-conceptual age at the time of study 37.4 (34.1-40.6) weeks. Twenty-four balance studies were performed and the materials analysed by atomic absorption spectroscopy. Infants with a "low" Mo intake received 0.024 (0.020-0.035) micromol/ kg per day, had a urinary excretion of 0.02 (0.008-0.045) and a retention of 0.0006 (-0.03 to 0.008) micromol/kg per day. Infants with a "high" intake received 0.284 (0.227-0.487) micromol/kg per day, had a urinary excretion of 0.243 (0.118-0.378) and a retention of 0.022 (-71.1 to 141.44) micromol/kg per day. Since the median urinary excretion exceeded 60% of the Mo intake at low and high intakes, sufficient resorption but minimal retention was assessed at low intakes of Mo.

CONCLUSION

In view of the limited knowledge of long-term exposure to an elevated molybdenum intake and the substantial retention observed at higher intakes, upper limits should be set for molybdenum concentrations in preterm infant formulas.

Molybdenum metabolism: stable isotope studies in infancy

The essential trace element molybdenum (Mo) is bound to and required for the function of molybdoenzymes, e.g. sulfite and xanthine oxidase. Dietary recommendations for early infancy are based on limited knowledge about its metabolism. 100Mo was used as an extrinsic tag to study the absorption and kinetics of excretion in infancy. 10 infants with a gestational age of 35 (30-39) weeks, a birth weight of 2.0 (0.9-2.3) kg and a post-natal age of 20 (10-54) days were studied. They received 25 microg 100Mo/kg with a feed of human milk or formula. Fractional urinary and fecal collections were conducted preceding the 100Mo intake and for 48-72 hours afterwards. The materials were analyzed by atomic absorption spectroscopy and inductively coupled plasma mass spectrometry. The median absorption of 100Mo intake was 97.5 (96.3 to 99.1) %. The retention of nutritive Mo intake and 100Mo in the study period was 11.2 (3.8-15.7) microg Mo/kg, equivalent to 35.7 (12.7-55.6) %. The Mo concentration increased to a peak value in urine within 8 (6-13) hours and in feces within 24 (7-48.5) hours. In addition, increases of copper in feces and urine were observed in 8 of 9 infants studied. Mo given orally is well resorbed in premature infants, and predominantly excreted in the urine. Dietary recommendations should prevent excessive intakes in infancy.

Evaluation of the Abbott Cell Dyn 4000 automated fluorescent reticulocyte measurements: comparison with manual, FACScan and Sysmex R1000 methods

The Abbott Cell Dyn 4000 (CD4000) is the first haematology analyser in which fully-automated reticulocyte measurements can be routinely determined by fluorescence as part of the full blood count. This communication reports the first evaluation of this method which was undertaken by three independent reference laboratories in Belgium, Germany and Italy. A total of 695 different samples was entered into the study which was designed to compare CD4000 reticulocyte information (enumeration and qualitative maturational data) with results determined in parallel with the existing manual (supravital staining) reference procedure, and two semi-automated fluorescent assays (Becton Dickinson FACScan and Sysmex R1000 instruments). These studies revealed good agreement between the CD4000 and the manual procedure, with no inter-method bias. Comparison of CD4000 and FACScan reticulocyte measurements, however, indicated a distinct tendency for the FACScan to give higher reticulocyte estimates than the CD4000. Finally, the comparison of the CD4000 with the Sysmex R1000 showed excellent agreement in the range 0-6% reticulocytes, although there was some inter-method bias in the higher range (> 15%). Analysis of agreement levels between the methods using specific 'clinical decision points' confirmed the tendency for overestimation by the FACScan, in that 58% of the samples with a reticulocytopenia of < 0.5% as defined by the CD4000 gave FACScan results within the normal range (0.5-1.8%). In contrast, there was absolute agreement between the CD4000 and the Sysmex R1000 for all reticulocytopenias. Comparison (195 samples) of instrument fluorescent reticulocyte maturation profiles demonstrated an exponential relationship (r = 0.78) between CD4000 IRF and R1000 HFR (highly fluorescent reticulocyte fraction) values. The suggestion that the CD4000 IRF values includes some of the MFR as well the HFR reticulocyte fraction was confirmed as the correlation between the CD4000 IRF and the Sysmex R1000 MFR plus HFR percentages was linear (r = 0.82). This study confirms a high performance level for the CD4000 automated fluorescent reticulocyte method.

In vivo interference of heparin bolus injection with photometric continuous lipase determination

The new photometric lipase determinations use diacylglycerols as substrates in a micellar solution, whereas the turbidimetric method is based on emulsified triacylglycerols degradation. Extrahepatic lipoprotein lipase, which is well known to be liberated by heparin from the capillar binding sites, may cleave triacylglycerols as well as diacylglycerols. When a heparin bolus injection is given to a patient, the released lipoprotein lipase renders high lipase activities in blood misleading for a pancreatic disorder.

Improved automated leucocyte counting and differential in newborns achieved by the haematology analyser CELL-DYN 3500

Automated leucocyte counts in newborns generated by the impedance principle are artificially affected by the high osmotic resistance of some newborn RBC and possibly by the high normoblast numbers present during the neonatal period. Erroneously high WBC counts may result. The haematology analyser CELL-DYN 3500 (Abbott Diagnostika GmbH, Wiesbaden-Delkenheim, Germany) has two different channels for the WBC count, an electrical resistivity (impedance) channel and a laseroptical channel. In combination with facultative extended lysis of resistant RBC before WBC count, this instrument is claimed to be very suitable for newborn blood analysis. We measured the WBC count and differential of 165 blood samples from newborns and cord blood on the CELL-DYN 3500. Reticulocyte count and manual differential including normoblasts were determined. Furthermore, some technical aspects of neonatal blood analysis were evaluated: precision, cell stability, effect of incorrect blood-anticoagulant ratio of small blood collecting tubes. The internal decision making process of the CELL-DYN 3500 selects the result either from the optical channel (identifies and excludes normoblasts) or from the resistivity channel (eliminates resistant RBC). This instrument gives a reliable and accurate WBC count and differential of neonatal samples even in blood samples with normoblasts and lytic resistant RBC. The result given by the CELL-DYN 3500 can be confirmed by a subsequent run in extended lyse mode.

[Reference values for plasma amino acids in the course of pregnancy]

Reference values for 26 plasma amino acids were determined by ion exchange chromatography in 29 healthy pregnant women (1st to 3rd trimenon). The results are given as P50 (P7-P93). In the course of pregnancy the concentrations of amino acids generally decrease. Threonine, however, shows a distinct, statistically significant increase. The interindividual concentration ranges are low and they show little change in the course of pregnancy. The data presented here are relevant for dietary treatment of metabolic disorders, e.g. maternal phenylketonuria in pregnants.

[Reference values for apolipoproteins and HDL-2/HDL-3 in childhood]

It is known from epidemiological studies, that high apolipoprotein B or low HDL-2 concentrations in serum are correlated with an increased risk for premature cardiovascular diseases. It was the aim of this study to generate reference values for apolipoproteins and HDL-cholesterol fractions to accomplish early diagnosis and therapy. All concentrations are age depending, being low at birth and increasing during the first years of life. This rise is more pronounced in apolipoprotein B than in apolipoprotein AI and HDL-2. Apolipoprotein II and HDL-3 reach later childhood values as early as at the end of the first month of life. The ratio of B and AI, which is a very good indicator for an increased risk for premature cardiovascular diseases, moves also distinctively upward during the first year of life.

[Sodium and potassium metabolism in infancy]

BACKGROUND

Recommendations for the concentration of most nutrients in infant formulas are based on their concentration in human milk. Industry succeeded in adapting sodium and potassium content in infant formulas to concentration found in human milk. Whether this adaptation affects on infants' mineral balances was studied in breast-fed and artificially-fed infants.

METHODS

Sodium and potassium balances were performed in 16 term male infants from their 3rd until their 17th week of life. The balances were performed at home and comprised up to five periods in intervals of three to four weeks. Each balance period consisted of subsequent three 24 h collections of milk, stool and urine samples. Ten infants were breast-fed, six received an adapted infant formula supplemented with copper, zinc and iron.

RESULTS

The breast-fed infants got a mean intake of 1 mmol Na/kg b w x day and a mean intake of 1.8 mmol K/kg b w x day. Man retention was 0.4 mmol Na and 0.7 mmol K/kg b w x day. The formula-fed infants received 1.9 mmol Na/kg b w x day and 2.1 mmol K/kg b w x day. Na- and K-retention in this group was 0.5 and 0.6 mmol/kg b w x day respectively. Although sodium intake in the formula-fed infants was nearly twice as much as in the breast-fed infants the difference in sodium retention was only small (0.4 vs 0.5 mmol/kg b w x day). The formula-fed infants got more potassium than the breast-fed infants, but potassium retention was the same in both groups.

CONCLUSIONS

With the adapted infant formula of this study the artificially fed infant was as well supplied with sodium and potassium as the breast-fed infant. A further reduction of the sodium concentration seems not to be useful.

Longitudinal zinc balances in breast-fed and formula-fed infants

Longitudinal zinc (Zn) balance studies were performed under domestic conditions in term breast-fed (n = 10), term formula-fed (n = 5; Zn concentration in the formula: 4 mg/l) and preterm formula-fed (n = 3) infants during the first 17 weeks of life. Samples of milk, urine and feces were analyzed by atomic absorption spectrometry. The median daily Zn intake in breast-fed infants decreased from 0.592 (0.457-0.829) mg Zn/kg body weight to 0.151 (0.095-0.304) mg Zn/kg body weight in the first 17 weeks of life; comparable values for bottle-fed term infants were 0.58 (0.511-0.701) and 0.674 (0.529-0.731) mg Zn/kg body weight. The median percent retention of Zn intake was 27 (-60 to 81.4)% in breast-fed infants and 21.5 (-42 to 64)% in formula-fed infants. In view of the urinary and fecal Zn losses measured, a daily intake of 0.3-0.5 mg Zn/kg body weight is considered to be sufficient to ensure a Zn retention equivalent to breast-fed infants. This requires a Zn concentration of 2-3 mg/l of Zn depending on milk volume intake.

Cholesterol determinations from skin puncture and venous blood have similar imprecisions

Comparison of cholesterol values from venous blood and skin puncture blood is difficult, because biological differences between both materials may be concealed or increased by the preanalytical imprecision of skin puncture. In 12 adults, we studied the variance of cholesterol and urea determination in 8 blood samples obtained by the puncture of 8 fingers and compared the results with the 8-fold determination of a venous sample drawn simultaneously. Our results show that the additional imprecision of skin puncture is low, and that the differences are not statistically significant. The mean values for cholesterol were 3.9% lower in skin puncture plasma than in venous plasma, whereas the mean values for urea were very similar.

Iron availability from an infant formula supplemented with bovine lactoferrin

Iron balance studies were performed in 16 term infants from their 3rd until their 17th week of life. The balance studies were performed at home and comprised five periods with an interval of 3 to 4 weeks, each consisting of three 24-hour collections of milk and stool samples. Seven infants were fed an adapted infant formula supplemented with bovine lactoferrin (100 mg/100 ml) and nine received the same formula without lactoferrin. The lactoferrin supplemented group received 169 micrograms iron/kg b.w. x day and retained 63 micrograms/kg b.w. x day. The mean iron intake of infants fed with the adapted formula without supplementation of lactoferrin was 118 micrograms/kg b.w. x day. The retention of iron was 43 micrograms/kg b.w. x day. Mean percentage retention of iron in the supplemented group was 36%, in the non-supplemented group 28%.

Urinary zinc excretion in infancy

In view of the conflicting data on urinary Zn excretion in infancy we investigated the possible influence of contamination, collecting methods, nutrition (human milk versus formula) and longitudinal changes during the first 16 weeks of life. Methodical investigation showed that special attention is necessary to avoid contamination due to the use of Zn-containing baby creams in the genital region. The sampling device for collection should include the smallest area of skin possible and the use of Zn-containing baby creams has to be avoided both during the collection and at least 24 hours prior to urine collection. Previous fractional urine sampling of the collecting method to be evaluated proves that erroneously high values are not obtained at the beginning of collection. Midstream urinary samples reduce the possibility of contamination. Increased urinary excretion was shown in pre-term infants under theophylline or coffeine medication. The median daily urinary Zn excretion in healthy breast-fed term infants declined significantly from 0.063 (0.027-0.111) mg per kg body weight at the age of 2 weeks to 0.018 (0.004-0.059) mg per kg body weight at the age of 16 weeks. Comparable values for formula-fed term infants were 0.029 (0.025-0.063) mg per kg body weight initially and 0.025 (0.007-0.059) mg per kg body weight at the end of the study. These values can be used as reference values for the urinary Zn excretion of healthy infants.

Selenium balances in young infants fed on breast milk and adapted cow's milk formula

Selenium intake, renal and fecal excretion, and retention were determined in 11 breast-fed term infants and in 9 term infants fed with an adapted cow's milk formula. In most cases three-day-balances were determined five times at the age of 2, 5, 8, 12, and 16 weeks. Analytical determination of selenium was by atomic absorption spectroscopy with a selenium hybrid system after wet ashing of samples. The mean breast milk concentrations of selenium show a significant decrease in the course of lactation from 31.0 micrograms/L in the first collecting period to 17.6 micrograms/L in the last one. The two formula milks contained 11.8 and 7.7 micrograms/L. Intake in the breast milk group was higher than in the formula group, whereas absolute renal and fecal excretion were essentially the same. This leads to a higher selenium retention in the breast-fed infants than in the formula-fed infants, where most of the balances are negative.

Trace element excess in PKU diets?

Knowledge of trace element requirements of infants with phenylketonuria (PKU) fed a semisynthetic diet is limited. Three infants with PKU detected early were studied longitudinally in classical balance studies for 72 h, under domestic conditions, at the ages of 2, 5, 8, 12 and 16 weeks. Iron, copper and manganese concentrations in the diet and faeces were determined by atomic absorption spectroscopy. The median concentrations in the diet (4.8 mg Fe/L, 1.7 mg Cu/L, 0.43 mg Mn/L) exceed those in human milk. This is mainly due to supplementation of the amino acid preparation used. The increased intake led to a significantly higher daily retention of Cu and Mn from the PKU-diet fed, with a median of 0.17 mg Cu/kg and 6.4 micrograms Mn/kg body weight; the median retention of Fe was 0.24 mg Fe/kg. Our results confirmed the doubts about the suitability of the present trace element supplementation in formula for infants with PKU during the first four months of life.

Longitudinal manganese and copper balances in young infants and preterm infants fed on breast-milk and adapted cow's milk formulas

1. Mn and Cu intake and retention in twenty full-term infants and six preterm infants were studied on the basis of 72 h balances. The age of the infants was 2-16 weeks and the gestational age of the preterm infants (triplets) 34 and 36 weeks. Three nutrition schemes were pursued: breast-fed, formula-fed with unsupplemented adapted formula and formula-fed with trace element supplementation. 2. The mean Mn concentration of all breast-milk samples (n 2339) was 6.2 micrograms/l. The two formulas had similar Mn concentrations (77 and 99 micrograms/l) but had different Fe, Cu (121 and 619 micrograms/l), Zn and I contents. The mean Cu concentration in mother's milk was 833 micrograms/l. 3. The following mean daily Mn intakes and retentions (micrograms/kg) respectively were measured: breast-fed full-term 1.06 (SD 0.43) and 0.43 (SD 0.65), formula-fed full-term 14.2 (SD 3.1) and 2.8 (SD 4.8), formula-fed preterm 15.0 (SD 2.2) and 0.06 (SD 5.87). The results for Cu were 114.5 (SD 22.3) and 88.0 (SD 46.5) micrograms/kg in breast-fed, 19.8 (SD 4.2) and 4.6 (-11.5-9.6) in the unsupplemented formula-fed and 106.4 (SD 18.9) and 55.5 (SD 20.3) in the supplemented formula full-term infant group. No significant influence of the trace element contents of the formulas on the relative retention of Mn or Cu was found. 4. Young preterm infants, and to some degree young full-term infants, often had negative Mn balances caused by a high faecal excretion. The formulas with a Mn concentration below 100 micrograms/l gave a sufficient supply of Mn. Preterm infants fed on the unsupplemented formula had a marginal Cu supply and their first balances were negative (-3.8 (SD 1.8) micrograms/kg). 5. In accordance with the estimated safe and adequate daily dietary intakes (recommended dietary allowances), formula-fed infants receive much more Mn than breast-fed infants and their absolute retention is higher. 6. Cu from breast-milk had a significantly better biological availability than that from cow's milk formula. If retentions similar to those in breast-fed infants are intended, we conclude, therefore, that cow's milk formula should be fortified with Cu up to a level of at least 600 micrograms/l.

Interstitial deletion of chromosome 13 involving the region 13q14

A patient with an interstitial deletion 13q14 is described who has decreased erythrocyte esterase D activity and who has not developed a retinoblastoma.

Iron balances in infant nutrition

Iron balance studies were performed in 17 full term male infants from their 3rd until their 17th week of life. The balance studies were made in the infant's home and comprised 5 periods with an interval of 3-4 weeks, each consisting of three 24-hour collections. Ten infants were breast-fed, 3 received an adapted infant formula (P1, iron content 1.1 mg/l) and 4 were given the same formula enriched with iron, copper and zinc (P2, iron content 10.35 mg/l). From the 3rd to the 17th week of life the breast-fed infants got a mean iron intake of 0.2 mg/kg body weight X 3 days and they retained 0.09 mg/kg b.w. X 3 days. The P1 group received 0.48 and 0.47 mg/kg b.w. X 3 days and retained -0.01 and -0.5 mg iron/kg b.w. X 3 days, while the P2 group had an intake from 5.04 to 6.38 mg b.w. X 3 days and retained between 1.13 and 3.66 mg iron/kg b.w. X 3 days. Comparing the 3 groups it can be concluded that the P1 group retained definitely less iron than the breast-fed group, whereas the P2 group retained 12 to 40 times more iron than the breast-fed babies.

Cholesterol fractions and triglycerides in children and adults with Down's syndrome

In 186 patients with Down's syndrome (age 1-68 yr) total cholesterol and triglycerides were determined, quantitative lipoprotein electrophoresis was performed and cholesterol fractions and beta/alpha-lipoprotein ratios were calculated. A reference group of 51 non-mongoloid mentally handicapped adults living in the same institutions were examined in the same way. Patients' total cholesterol, beta-cholesterol and triglycerides did not differ from the controls. However, alpha-cholesterol was significantly lower and the beta/alpha-lipoprotein ratio significantly higher in patients, findings which are associated in the general population with a high risk for premature atherosclerosis. Interestingly, mortality causes and pathological findings in Down's syndrome show no increased frequency of cardiovascular diseases.

Further evaluation of the SG test strip for estimation of urinary osmolality

The mass densities of 2000 urines from children and 2000 urines from adults were determined with the new test strip, Multistix SG, and the results were compared with osmolality measurements. Normal urinary parameters were investigated for possible interference with the test strip reading. Variations in the pH and ionic composition of urine considerably influenced the test strip reading, whereas nonionic compounds, such as glucose and urea, showed practically no interference. For patients on a normal diet and without metabolic diseases, the new test strip is more appropriate than urometry for the determination of the mass density of the urine.

[Vitamin and zinc levels in leukemic children during induction therapy (author's transl)]

In 23 leukemic patients treated according to the West Berlin-protocol, we studied prospectively the plasma levels of the vitamins A (and carotinoids), B1, B2, B6, C, and E, as well as serum zinc values. Blood was drawn on days 0 (before treatment), 15, 29, and 57 of induction therapy. With one exception, plasma vitamin levels did not change significantly during treatment; however, vitamin A increased in the first and decreased in the second phase of induction (p less than 0.01) without clinical signs or symptoms. The serum levels of zinc (p less than 0.05) and the alkaline phosphatase fell continuously from day 0 to 29, but there was no correlation between these two parameters in the same patient. Clinical symptoms of zinc deficiency were not observed. We conclude: 1) That plasma vitamin levels in this limited population are generally unaffected by the underlying malignant disease, the aggressive therapy and altered feeding behaviour, and 2) that the significant decrease of serum zinc does not play a major role in the expression of clinical and biochemical side effects of cytotoxic therapy.

Calculation factors and reference values for quantitative lipoprotein electrophoresis in childhood

Agarose gel electrophoresis of lipoproteins combined with quantitative densitometry (Lipidophor) and total cholesterol determination enables the calculation of alpha-, pre-beta-and beta cholesterol. This method is quick, precise and requires less than 100 microliters serum. The calculation factors originally derived from adults were re-evaluated and corrected for children. This was achieved by iterative calculation of the results obtained by quantitative densitometry and by enzymatic determination of the cholesterol contents in electrophoretically separated lipoprotein bands. Thus, calculation factors for children were obtained, which were used for the evaluation of reference values for alpha-, pre-beta- and beta-cholesterol and for the beta/alpha-lipoprotein ratio based on a reference group of 575 healthy children of 5-18 years of age.

A new method for the determination of serum iron: potentiostatic coulometry with the Ferrochem 3050

Potentiostatic coulometry allows the fast determination of iron in serum samples of 50 microliters serum or less. Precision, accuracy, specificity and practicability of the method were evaluated using the Ferrochem 3050, and found to be favourable. This method can therefore be recommended to all laboratories in which small sample volumes have to be analysed.

Increased nucleotide catabolism after cerebral convulsions

Cardiazol induced seizures in rabbits showed that the highest oxypurine concentrations can be detected in the CSF 1 hour after the convulsions. There is a sharp decline continuing until the third hour. After that the CSF values remain nearly constant until the 24th hour being about ten times higher than in the controls. There is a good correlation of these results obtained through the densitometric thin-layer, enzymatic-oxymetric, and HPLC-methods. Creatinine and potassium were raised only during the first two hours postconvulsively. Uracil appeared in the CSF slightly higher at the 1 hour and at the 12 and 24 hour values. A parallel increase of the oxypurine and creatinine concentrations was found in the serum between 30 to 120 minutes postconvulsively. After that the raised serum values decreased slowly to the initial values. CSF samples were examined in 31 children postconvulsively: Hypoxanthine was found to be raised in 8 of 12 patients with severe grand mal seizures, 1 of 6 patients with hypsarrhythmia, 1 of 8 patients with short seizures (less than 2 min) and in all 5 patients with petit mal status. In contrast to these groups the hypoxanthine concentrations was raised only in 2 of 20 children with aseptic meningitis. The difference between the group of children with convulsions and the group of children with aseptic meningitis is significant (p less than 0.005). Also, the frequency of raised uric acid concentration is higher in the group of children with convulsions (70%) than in the group of children with aseptic meningitis (40%); (p less than 0.05).

[Initial experiences in psychiatric emergency service. Comments on the prevention or indication of compulsory hospitalization in accordance with the Hamburg Law on Aid and Protective Measures in Mental Diseases (author's transl)]

On the basis of the rules of the Hamburg Law on Aid and Protective Measures in Mental Diseases, a psychiatric emergency service operates at night and on weekends. This emergency service is called upon to decide on the need for compulsory hospitalization and to prevent the same, if possible, via therapeutic alternatives. The article illustrates by documents an initial phase of the activities of this public service. Within the framework of a preliminary study, 63 recorded incidents of service by four physicians are presented who collected data on the situation encountered by them at the time of examination, on the social and anamnestic background of the patients, on their psychiatric evaluation and on the indication for compulsory hospitalization or alternative treatment methods. 22% of the patients were subjected to compulsory hospitalization. Provisional hypotheses on the conditions under which compulsory hospitalization becomes more probable, are developed from the recorded data. The concept of the risk situation is specially reflected upon. The therapeutic possibilities in connection with institutional factors are discussed with a view to promote further development of crisis intervention in the sense of preventing compulsory hospitalization.

[Nephropathic and benign cystinosis (author's transl)]

Cystinosis is a rare, autosomally and recessively inherited disorder of amino-acid metabolism with ocular involvement. Four patients with this disease are reported on. The clinical signs of the first patient, who had nephropathic cystinosis, are compared with the signs and symptoms of the benign phenotype (benign cystinosis). In both nephropathic and benign cystinosis, multiple crystals were found in the cornea and conjunctiva. In the second case a large number of crystals were demonstrated in bone-marrow smears and conjunctival sections; a chromatogram of the conjunctiva indicated the presence of cystine. Although the results of an analysis of cultured fibroblasts from this case were contradictory, an elevated cystine level appeared likely. Crystals were also found in conjunctival sections from the third case. In the fourth case it proved impossible to demonstrate crystals clearly in either the bone marrow or in conjunctival sections. There was no evidence of any other cause of the corneal or conjunctival crystals.

Quantitative measurements of the urinary excretion of creatinine, uric acid, hypoxanthine and xanthine, uracil, cyclic AMP, and cyclic GMP in healthy newborn infants

Serum creatinine, uric acid, and hypoxanthine and xanthine concentrations were determined in 17 mother-infant pairs at the time of delivery. Creatinine and uric acid levels were nearly similar, but hypoxanthine and xanthine were more than twice as high in the blood of the infants than in the blood of their mothers. In the same newborns the urinary excretion of creatinine, uric acid, hypoxanthine and xanthine, uracil, cAMP, and cGMP was measured on the first and fourth day of life. Creatinine, uracil, and cAMP increased, hypoxanthine and xanthine, and cGMP decreased, whereas the output of uric acid was nearly the same on both days. Correlations of the excreted substances to each other were calculated.

[Reference values of lipid metabolism in childhood (author's transl)]

Sera of 949 children were analyzed for cholesterol and triglycerides by enzymatic methods and for lipoprotein pattern by electrophoresis. For the first time all ages were examined. Two independent collectives were compared: healthy pupils and sick children without disturbances of lipid metabolism. The values of these groups showed no significant difference. In infancy cholesterol and triglycerides levels heavily depend on age, while later in childhood values change little. Highest reference values are 6.36 mmol/l (= 246 mg/dl) for cholesterol and 1.74 mmol/l (= 154 mg/dl) for triglycerides.