[Long-term outcome of preterm neonates: the message behind the statistics]

In view of the current progress in neonatal intensive care, the present outcome of former preterm neonates does not necessarily reflect the future outcome of today's preterm neonates. In spite of this statistical uncertainty, long-term follow-up studies performed in the past few years point to the fact that the sequelae of prematurity may appear well beyond infancy and may be revealed in varying manners with increasing age. Therefore, a chronological account of the consequences of prematurity is given in this paper, ranging from perinatal mortality/morbidity to the problems to be observed during early childhood, preschool age, and adolescence right up to the long-term sequelae arising in later adulthood. Within this context, a two-fold paradigm shift in neonatology becomes apparent in that, first, the outcome of preterm neonates is not a result of immaturity per se, yet is significantly influenced by the factors leading to preterm birth (inflammation, intrauterine growth restriction), and, second, the sequelae of prematurity do not end with the end of neonatal intensive care, but are greatly modulated by familial conditions in their further course. Even though the statistical data are still subject to changes, these insights form the basis of a structured long-term follow-up of preterm neonates which, after the progressive establishment of acute treatment strategies, will become an increasingly important challenge to neonatology within the framework of paediatrics.

Electron microscopy and microcalorimetry of the postnatal rat heart (Rattus norvegicus)

The interplay of ultrastructure and tissue metabolism was examined in neonatal, infant and adult rat hearts by electron microscopy and microcalorimetry. Morphometry was used to determine parameters of oxygen diffusion capacity (distance between capillaries and mitochondria, capillary surface density) and oxidative metabolic capacity (mitochondrial volume fraction). Thin slices and large samples of living tissue were examined calorimetrically to quantify aerobic metabolism and ischemia tolerance, respectively. After birth, rat hearts grow in parallel to body mass and show characteristics of cellular hypertrophy. Capillary surface density increases from neonatal to infant rats, and decreases to an intermediate value in adult rats. The distance between capillaries and mitochondria shows no significant changes throughout postnatal development. Mitochondrial volume fraction increases continuously until adulthood. The specific aerobic tissue metabolic rate is higher in the neonatal than in the infant and adult rat. However, the ischemic decline in metabolic rate is much slower in the neonatal rat, reflecting an elevated hypoxia tolerance. In conclusion, the neonatal rat heart exhibits a high metabolic rate despite a low mitochondrial volume fraction. The subsequent structural rearrangements can be interpreted as long-term adaptations to the increased postnatal workload and may contribute to the progressive loss of hypoxia tolerance.

Neonatal platelets from cord blood and peripheral blood

The haemostatic system in neonates is different from that of adults, possibly contributing to an increased incidence of bleeding disorders, such as intracranial hemorrhage. In this study, we analyzed platelets from cord blood and peripheral blood, collected at three time points after delivery from 20 term and 37 preterm neonates as well as blood from 20 healthy adults. Platelet membrane glycoproteins (GP) were quantified and P-selectin expression and PAC-1 binding ability before and after stimulation with TRAP were analyzed by whole blood flow cytometry. We found no significant differences in neonatal platelets from cord blood and peripheral blood within the first 24h of life. Platelets from infants less than 30 weeks of gestation expressed lower levels of GP (33271+/-9381 vs. 44085+/-17287 for GPIIIa, P<0.05) and were less reactive than platelets from term newborns (4.3+/-3.3 vs. 20.1+/-11.8% PAC-1 positive platelets after stimulation with TRAP, P<0.05). A significantly lower level of GPIIb/IIIa expression on platelets from peripheral blood was seen in term newborns as well as preterm infants, compared to adults. There was only a partial enhancement in the degranulation ability (alpha-granules) (13.4+/-12.3 vs. 50.3+/-16.1% P-selectin positive platelets, P<0.05) and no significant increase for PAC-1 binding (13.6+/-10.9 vs. 15.3+/-5.9% PAC-1 positive platelets, P=0.8) during the first 12 days of life. In conclusion, we could demonstrate that neonatal platelet reactivity increases with gestational age.

Positive control of swarming, rhamnolipid synthesis, and lipase production by the posttranscriptional RsmA/RsmZ system in Pseudomonas aeruginosa PAO1

In Pseudomonas aeruginosa, the small RNA-binding, regulatory protein RsmA is a negative control element in the formation of several extracellular products (e.g., pyocyanin, hydrogen cyanide, PA-IL lectin) as well as in the production of N-acylhomoserine lactone quorum-sensing signal molecules. RsmA was found to control positively the ability to swarm and to produce extracellular rhamnolipids and lipase, i.e., functions contributing to niche colonization by P. aeruginosa. An rsmA null mutant was entirely devoid of swarming but produced detectable amounts of rhamnolipids, suggesting that factors in addition to rhamnolipids influence the swarming ability of P. aeruginosa. A small regulatory RNA, rsmZ, which antagonized the effects of RsmA, was identified in P. aeruginosa. Expression of the rsmZ gene was dependent on both the global regulator GacA and RsmA, increased with cell density, and was subject to negative autoregulation. Overexpression of rsmZ and a null mutation in rsmA resulted in quantitatively similar, negative or positive effects on target genes, in agreement with a model that postulates titration of RsmA protein by RsmZ RNA.

[Aseptic meningitis after intrathecal infusion of a parenteral nutrition solution: examples of rare malpositions of central venous catheters in preterm neonates]

BACKGROUND

Central venous catheters are an indispensable part of intensive care. In the management of preterm neonates, these are introduced after puncture of a peripheral subcutaneous vein. The catheters are supposed to be pushed forward with the venous flow. A chest X-ray is usually performed for verification of the position of the catheter. Localization of the tip of the catheter is often very difficult because of its extremely small diameter.

METHODS

A malposition of a central venous catheter resulting in intrathecal infusion of parenteral nutrition and subsequent aseptic meningitis in a preterm neonate is presented. Further cases of catheter malpositions leading to arthrography, arteriography and incorrect position in various parts of the venous system are discussed.

DISCUSSION AND CONCLUSION

The case reports demonstrate that wire-guided central venous catheters are not only advanced by the forward blood flow but can also inadvertently end up in undesired sites and may thus induce serious side effects.

[Infant botulism and sudden infant death syndrome]

Infant botulism represents a distinct entity of botulism. Ingestion of the ubiquitously present spores of Clostridium botulinum leads to germination of the organism and neurotoxin production in the infant intestine. Symptoms typically develop gradually in contrast to classical food botulism in which an acute onset of symptoms shortly after the ingestion of preformed toxin in a food is characteristic. Microbiologically, the diagnosis is established by identification of Clostridium botulinum organism and toxin in stool specimen. However, positive results in these tests provide only indirect evidence for the clinical relevance of the neurotoxin since asymptomatic carriers have been found. The toxin irreversibly blocks the release of acetylcholin from the motoric end plate which results in muscle weakness and paralysis. Depending on the amount of toxin produced, infant botulism exhibits a broad clinical spectrum ranging from oligosymptomatic forms to a fulminant course with acute respiratory failure within hours leading to sudden death. Unrecognized mild forms or beginning muscle weakness can be a co-factor for other risk factors of sudden infant death (SIDS). In studies analyzing infants who died from SIDS, botulism bacteria or toxin were found in up to 20 % of cases. Infant botulism therefore represents an important differential diagnosis of unexplained and inconclusive muscular hypotonia in the first year of life.

Mouse models of human cancer web-based resources

The Mouse Models of Human Cancers Consortium (MMHCC) is a collaborative program designed to derive and characterize mouse models of human malignancies. To enhance information and resource exchange among the MMHCC investigators and other cancer research scientists, the NCI Center for Bioinformatics (NCICB, http://ncicb.nci.nih.gov/) has developed web-based resources that are freely available to the cancer research community. These resources include a website (http://emice.nci.nih.gov) and databases for cancer models (http://cancermodels.nci.nih.gov) and cancer images (http://cancerimages.nci.nih.gov).

[Phylogeny of Mammalian metabolism]

Mammals are at the end of a gradual metabolic evolution in the course of which the step from anaerobic to aerobic cellular metabolism and the transition from water to land life formed the basis for an increase in metabolic rate (from brady- to tachymetabolism). The increased metabolic rate and the resulting endogenous heat production were the preconditions for enhanced long-term performance as well as for homeothermy which allowed mammals and birds to invade temperate zones. However, the underlying increase in membrane permeability also results in an increased energy demand (for membrane pump activity) which leads to the reduced hypoxia tolerance of mammals and requires a permanent substrate supply. As an adaptation to a seasonal discrepancy between increased thermoregulatory energy demand and decreased food supply, some small mammals apparently extended the newly evolved non-REM-sleep into hibernation. Mammalian hibernation is characterized by a profound metabolic reduction which is influenced by acidosis and limited to a tolerable degree by maintained thermoregulation. The lower limit of cooling seems to be determined by a critical minimal metabolic rate which is common to all mammals. The higher the normothermic metabolic rate, the lower is the temperature at which this minimal metabolic rate is reached. Since specific (i. e., weight-corrected) basal metabolic rate increases with decreasing body mass, small mammals exhibit a higher hypothermia tolerance than larger ones. On the other hand, the metabolic decrease to a uniform minimal level reflects an inactivation of the overall metabolic size relationship and, thus, forms a counterpart to the metabolic increase from a lower fetomaternal to the higher size-related level, occurring after birth. The postnatal metabolic increase which favours the onset of thermoregulation, parallels the increase in oxygen tension at the transition from fetal to adult circulation and, thus, probably enables mammalian neonates to readjust their metabolic needs in response to hypoxia. There is increasing evidence that, similar to the step from anaerobiosis to aerobiosis, the increase in metabolic rate resulting from any increase in oxygen supply is a general principle of evolution that, apart from its further adaptive benefits, protects tissues from oxygen excess and subsequent oxidative stress.

[Universal newborn hearing screening program in Würzburg. Experience with more than 4000 newborns and the influence of non-pathological factors on the test results]

BACKGROUND

The BERAphon(R) method employing a special headphone and the time-course step-stimulus algorithm offers a quick and reliable tool for universal hearing screening in newborns. An ABR-based universal newborn hearing screening program has been established in Würzburg since August, 1997. Until August 2001, 4115 newborns have undergone primary and/or control-screening with the BERAphon(R). The validity of this method was further examined by testing the effects of non-pathological factors such as gender, age, Apgar score, pH value of the umbilical cord, head circumference and duration of pregnancy on the ABR wave V latency in 415 infants.

RESULTS

Out of 3930 infants who were primary screened, 27 infants were diagnosed to have hearing loss. Furthermore, hearing loss was detected in 35 out of 185 infants referred for control screening. Non-pathological factors showed a minor effect on the test results. Apgar score, gender or chronological age did not have any significant effects on the latency of wave V. Duration of pregnancy, pH value of the umbilical cord or head circumference showed a significant but weak correlation with wave V latency.

CONCLUSIONS

Only non-pathological factors related to maturation had a minor effect on ABR measurements using the time-course-step-stimulus algorithm. The BERAphon(R) method has proven to be a reliable, robust method giving information related to the hearing threshold and accordingly can be used reliably for hearing screening in newborn infants.