Incorrect umbilical vein catheterization is associated with severe periventricular hemorrhages and mortality in extremely premature newborns

OBJECTIVE

To investigate the relationship between umbilical vein catheter (UVC) placement and death in extremely premature newborns (<29 weeks gestation).

STUDY DESIGN

Utilizing a retrospective, case-control study design, results for newborns that received UVC placements and died were compared with those who received UVC placements and survived (n = 719) by univariate and multiple logistic regression analyses.

RESULT

Death rate was 30% in infants with low lines versus 16% in those without (p = 0.012). High UVC tip placement significantly and independently increased severe periventricular hemorrhages (p = 0.014). Severe periventricular hemorrhage increased death rates by 3-fold independent of gestational age (p <  0.001). Proper line placement significantly reduced severe periventricular hemorrhage by 2.5-fold independent of gestational age (p = 0.019).

CONCLUSION

In extremely premature newborns, incorrect UVC placement is significantly associated with death through its relation to severe periventricular hemorrhage.

Surfactant Releases Internal Calcium Stores in Neutrophils by G Protein–Activated Pathway

Pulmonary surfactant with surfactant-associated proteins (PS+SAP) decreases pulmonary inflammation by suppressing neutrophil activation. We have observed that PS+SAP inserts channels into artificial membranes, depolarizes neutrophils, and depresses calcium influx and function in stimulated neutrophils. We hypothesize that PS+SAP suppresses neutrophil activation by depletion of internal Ca++ stores and that PS+SAP induces depletion through release of Ca++ stores and through inhibition of Ca++ influx. Our model predicts that PS+SAP releases Ca++ stores through insertion of channels, depolarization of neutrophils, and activation of a G protein–dependent pathway. If the model of channel insertion and membrane depolarization is accurate, then gramicidin—a channel protein with properties similar to those of PS+SAP—is expected to mimic these effects. Human neutrophils were monitored for [Ca++] responses after exposure to one of two different PS+SAP preparations, a PS-SAP preparation, gramicidin alone, and gramicidin reconstituted with phospholipid (PLG). [Ca++] responses were reexamined following preexposure to inhibitors of internal Ca++ release or the G protein pathway. We observed that (i) 1% PS+SAP—but not PS-SAP—causes transient increase of neutrophil [Ca++] within seconds of exposure; (ii) 1% PLG—but not gramicidin alone—closely mimics the effect of PS+SAP on Ca++ response; (iii) PS+SAP and PLG equally depolarize neutrophils; (iv) direct inhibition of internal Ca++ stores releases or of G protein activation suppresses Ca++ responses to PS+SAP and PLG; and (v) preexposure to either PS+SAP or PLG inhibits Ca++ influx following fMLP stimulation. We conclude that PS+SAP independently depolarizes neutrophils, releases Ca++ from internal stores by a G protein-mediated pathway, and alters subsequent neutrophil response to physiologic stimulants by depleting internal Ca++ stores and by inhibiting Ca++ influx during subsequent fMLP activation. The mimicking of these results by PLG supports the hypothesis that PS+SAP initiates depolarization via channel insertion into neutrophil plasma membrane.

Impact of umbilical catheterization on morbidity and mortality in extremely premature newborns

OBJECTIVE

Investigate the benefit of umbilical catheterization upon survival and selected morbidities in extremely premature newborns (<28 weeks gestation). Outcomes of successfully catheterized extremely premature newborns are compared with others who cannot be successfully catheterized, and we hypothesize that umbilical catheterization promotes survival and reduces morbidities.

STUDY DESIGN

Utilizing a retrospective, cohort study design, survival and outcomes of catheterized and non-catheterized newborns (n = 722) were compared by univariate and multiple logistic regression analyses.

RESULTS

Of all newborns, 66.8% had both umbilical arterial catheter (UAC) and umbilical venous catheter (UVC) placements, 15.0% had only UAC, 13.7% had only UVC, and 4.6% had neither. Overall survival was 82.5%. Survivals with and without UAC were 82.5% and 82.6% (NS), but survival with UVC was 80.7% versus 90.1% without UVC (p = 0.012). Analysis of risk factors associated with death during umbilical catheterization reaffirmed that death remained significantly dependent upon UVC placement (OR = 35.7; 95% CI: 3.7-347.3, p = 0.002).

CONCLUSION

Successful umbilical catheterization of extremely premature newborns does not provide benefit through promotion of survival or reduction of morbidities when compared to others who are not successfully catheterized at the umbilicus.

Multicenter study to determine antibody concentrations and assess the safety of administration of INH-A21, a donor-selected human Staphylococcal immune globulin, in low-birth-weight infants

Nosocomial or late-onset sepsis is a common complication among premature infants, with a frequency inversely correlated with birth weight. Increased susceptibility to infection is due in part to an immature humoral (antibody-mediated) immune response. This study investigated the pharmacokinetics (PKs) and safety of a donor-selected specific intravenous immune globulin (IVIG) preparation, INH-A21 (Veronate), for prevention of sepsis in premature infants. Thirty-six infants weighing between 500 and 1,250 g during the first postnatal week were eligible to begin a series of up to four intravenous infusions of 500 or 750 mg/kg of body weight INH-A21. Blood samples were analyzed for antibodies against the Ser-Asp dipeptide repeat G (SdrG) and clumping factor A (ClfA) surface proteins of staphylococci. Sparse sampling and population PK analyses were performed to derive PK parameters. Following administration of the 500- and 750-mg/kg doses, the estimated average steady-state levels of anti-ClfA were 6.1 U/ml and 9.2 U/ml, respectively, and those of anti-SdrG were 5.2 U/ml and 7.7 U/ml, respectively. The elimination half-lives for anti-ClfA and anti-SdrG were 719 h and 701 h, respectively, and the clearances were 0.18 ml/h and 0.21 ml/h, respectively. In the final model, the values of the PK parameters were independent of gestational age. Both doses of INH-A21 were well tolerated, and the safety profile was similar to those of other IVIG preparations. These results suggest that a shorter dosing interval should be utilized between the first and second doses to achieve and maintain higher titers of anti-ClfA and anti-SdrG antibodies. Further studies examining INH-A21 for the prevention of late-onset sepsis in infants within the weight range studied are warranted.

Auditory brainstem response detects early bilirubin neurotoxicity at low indirect bilirubin values

When sedation, prematurity or other disease processes mask symptoms in the clinically ill newborn, serum bilirubin concentration is monitored as the sole indicator of kernicterus risk. This case emphasizes the value of auditory brainstem responses for the management of indirect hyperbilirubinemia complicated by prematurity, hemolytic anemia, asphyxia, and direct hyperbilirubinemia.

Current practice regarding the enteral feeding of high-risk newborns with umbilical catheters in situ

OBJECTIVE

Textbooks recognize the controversy of concomitant enteral nutrition (EN) during umbilical catheter usage in high-risk newborns, but support for the practice varies. There is only one clinical trial examining these practices in a small but randomized, controlled trial of enterally fed newborns with umbilical arterial catheters (UACs) in situ, and that trial did not demonstrate any adverse consequences. We speculate that concomitant EN with umbilical catheter usage is more common than some textbooks suggest-practiced by at least 20% of all US neonatal intensive care units (NICUs). The objective of this study is to determine the prevalence of NICUs where high-risk newborns with UAC or umbilical venous catheter (UVC) placement receive concomitant EN.

METHODS

Medical Directors listed in the American Academy of Pediatrics United States Neonatologist and Perinatologist Directory were surveyed by mail. On return of surveys, responses to multiple choice questions were recorded by electronic scanning and validated by manually conducted quality control checks. NICU identities were recorded by code to maintain anonymity.

RESULTS

Following 2 requests for survey participation, 70% (549/785) of surveys were returned. Respectively, 82% and 62% of NICUs with and without training programs were represented. On average, surveyed medical directors had practiced neonatal medicine 18.1 +/- 0.3 years. Of surveyed NICUs, 99% reported placement of UVCs and UACs. Of the 92% believing that it is safe to provide trophic EN to newborns with UVCs in place, 51% practiced this some of the time, and 37% practiced it most of the time. By comparison, it was reported that newborns with UACs in place receive trophic EN most of the time (30%), some of the time (49%), or none of the time (22%). Of the 80% believing that it is safe to provide more complete EN to newborns with UVCs in place, 44% practiced this some of the time, and 24% practiced it most of the time. For newborns with UACs in place, more complete EN was provided most of the time (15%), some of the time (36%), or none of the time (49%).

CONCLUSIONS

Concurrent UVC and UAC usage with EN is more commonly practiced than suggested in textbooks or published articles. The relative risk-benefit profiles of these practices remain uncertain secondary to the limited number of controlled clinical observations and to the infrequent occurrence of adverse events. A prospective, multicenter, controlled trial would address the continued advisability of these unexpectedly common practices.

Pulmonary surfactant proteins insert cation-permeable channels in planar bilayers

Pulmonary surfactant, a mixture of lipids and proteins, promotes lung ventilation by reduction of surface tension at air-fluid interfaces. Exogenous surfactants containing hydrophobic proteins induce biological effects in lungs that are not fully explained by reduction of surface tension and are not induced by surfactants lacking proteins. We hypothesized that hydrophobic proteins from surfactant insert in membranes to induce channel activities that contribute to the observed biological effects of surfactant. To test for channel insertion by surfactant, planar lipid bilayers were monitored electrophysiologically in the presence of either intact pulmonary surfactant or extracted surfactant proteins reconstituted with phospholipids or directly added to bilayer lipids prior to membrane casting. In this in vitro model, both intact surfactant and extracted surfactant proteins initiated gated channel activities with slope conductances averaging 40 pS. Observed reversal potentials confirmed monovalent cation conductance, and conductance of smaller monovalent cations was selective. Voltage dependence of channel openings and rectification of channel current were not observed. These results confirm that hydrophobic surfactant proteins induce channel-mediated transport in artificial membranes. We speculate that pulmonary surfactants, in addition to reducing surface tension at air-fluid interfaces, initiate physiological and therapeutic effects in lung by cation channel insertion at exposed epithelial membranes.

Surfactant modulates calcium response of neutrophils to physiologic stimulation via cell membrane depolarization

Pulmonary surfactant (PS) reduces inflammation in the lung by poorly understood mechanisms. We have observed that surfactant-associated proteins (SAP) insert monovalent cation channels in artificial membranes. Neutrophils are primary mediators of acute pulmonary inflammation, and their functions are activated by increases in cytosolic ionized calcium concentration ([Ca2+]) and by changes in membrane potential. We hypothesize that PS inserts SAP-dependent cation channels in neutrophils, causing membrane depolarization, altered [Ca2+] response, and depressed activation. Human neutrophils were isolated, exposed to PS+SAP (1% Survanta), PS-SAP (1% Exosurf), or buffer, and washed before activating with selected stimulants. PS+SAP reduced phorbol ester- and formyl peptide-stimulated adherence and aggregation by 38% (p < 0.05) and 54% (p < 0.02), respectively. PS+SAP also inhibited the formyl peptide-induced [Ca2+] response of neutrophils (p < 0.01), but only in the presence of external Ca2+. Further characterization of this inhibition demonstrated that PS+SAP blocked formyl peptide-induced influx of both Ca2+ and Mn2+, and that this inhibition was present during activation by other neutrophil stimulants (IL-8, immune complexes). Prior depolarization of neutrophils with gramicidin-D similarly inhibited the [Ca2+] response of neutrophils to formyl peptide, and analysis of neutrophil membrane potential by 3,3'-dipentyloxaearbocyanine iodide (diOC5(3)) fluorescence revealed that PS+SAP induced rapid neutrophil depolarization. In contrast, PS-SAP exhibited little effect on neutrophil function, [Ca2+], or membrane potential. We conclude that PS+SAP decreases neutrophil adherence and aggregation responses, blocks Ca2+ influx after physiologic stimulation, and decreases membrane potential. We speculate that these effects are caused by membrane depolarization via SAP-dependent cation channel insertion, and that all of these effects contribute to the antiinflammatory properties of PS+SAP.

Detection of pathogen transmission in neonatal nurseries using DNA markers as surrogate indicators

OBJECTIVE

Nosocomial infections are a major problem confronting neonatal intensive care units (NICUs). This study was conducted to determine if DNA markers designed from the cauliflower mosaic virus (CaMV 35S DNA) can serve as surrogate indicators of nosocomial pathogen transmission in NICUs.

METHODS

Regions of cauliflower CaMV 35S promoter DNA were designed to serve as surrogate markers of microbial transmission pathways. Each of 6 pods within the NICU under study houses 8 newborn infants. DNA marker was placed on the telephone handle in only 1 of the 6 NICU pods (study pod). Bedside caregivers were blinded as to when placebo or marker were placed in the pod. Thirty-two samples were collected from predetermined sites within each pod at 0, 4, 8, 24, and 48 hours and 7 days after DNA placement. Similar sites were sampled in each of the 6 pods. Additional samples were collected concurrently from areas of the NICU segregated from direct patient care. Polymerase chain reactions were performed on collected samples, and products were analyzed by agarose gel electrophoresis.

RESULTS

One thousand three hundred samples of the environment and hands of personnel were collected and analyzed. Within the study pod, 58% of sites tested positive for the DNA marker throughout all time points; positive sites peaked at 8 hours (78%) and declined to 23% positive at 7 days. The other 5 pods had a mean of 18% of sites positive throughout the 7 days and exhibited a similar decline throughout time. The most consistently positive sites within all pods were the blood gas analyzers, computer mice, telephone handles, medical charts, ventilator knobs, door handles, radiant warmer control buttons, patient monitors, and personnel hands. In areas outside the pods, the nurse's station, resident physician charting area, changing room, and staff break room had a mean of 50% positive sites throughout all time points.

CONCLUSIONS

DNA markers proved useful as safe, surrogate indicators of microorganism transmission within and outside pods in the NICU. We speculate that utilization of these techniques in the hospital environment will provide important information about transmission of pathogens in the NICU, assist in developing and enforcing cleaning procedures, and permit testing of educational intervention programs targeting a decrease in nosocomial infections.nosocomial infection, neonatal intensive care, DNA marker, polymerase chain reaction, infection control.

Human milk effects on neutrophil calcium metabolism: blockade of calcium influx after agonist stimulation

Neutrophils are the predominant cellular mediators of acute inflammation, and human milk suppresses multiple neutrophil functions. We sought to determine whether these effects were mediated through disruption of normal intracellular Ca2+ homeostasis. Exposure of human neutrophils to human milk, followed by washing, resulted in altered Ca2+ transient responses to formyl-peptide stimulation in which the peak cytosolic free Ca2+ concentration ([free Ca]) was the same as in unexposed cells, but the postpeak decline in [free Ca] was more rapid. This effect was observed after human milk exposures as brief as 10 s, persisted for up to 4 h after human milk removal, and was concentration dependent. On the basis of experiments examining Ca2+-free conditions followed by Ca2+ supplementation, and experiments examining spontaneous and stimulated manganese and barium influx into neutrophils, the human milk effect was due to blockade of Ca2+ influx. Decreased Ca2+ transient responses to other physiologic stimuli (IL-8, opsonized Staphylococcus aureus, and immune complexes) were observed after human milk exposures. Rat intestinal epithelial cells and HL-60 cells failed to show these effects, suggesting a selective effect on mature inflammatory cells. Characterization of the Ca2+-blocking activity showed it was heat and acid stable in human milk with a molecular mass between 30-100 kD. Commercial human milk lactoferrin exhibited Ca2+ influx blockade activity, but recombinant human lactoferrin showed none. Separation of the activity by heparin affinity chromatography showed that it was distinct from lactoferrin. Human milk-induced blockade of Ca2+ influx provides a potential mechanism for broad suppression of neutrophil functions that may contribute to the antiinflammatory properties of human milk.

Membrane depolarization and depletion of intracellular calcium stores are associated with delay of apoptosis in human neutrophils

Apoptosis occurs rapidly in human polymorphonuclear leukocytes (PMN) after exposure to 1 mM cycloheximide (CHX). We examined whether this form of stimulated apoptosis altered either resting cytosolic free Ca2+ concentrations ([free Ca]) or membrane potential (psi) in PMN and found no significant effects. However, manipulation of either PMN intracellular Ca2+ stores or psi was found to delay CHX-induced apoptosis. Depletion of PMN intracellular Ca2+ stores with thapsigargin caused membrane depolarization and significantly delayed CHX-induced apoptosis based on both morphological and annexin-V-fluorescein isothiocyanate binding criteria. Short-term suspension (4 h) of PMN in Ca2+-free buffer depleted internal Ca2+ stores, induced membrane depolarization at 2.5 h, and delayed spontaneous (24 h) apoptosis but had no effect on CHX-induced apoptosis. Rapid membrane depolarization with 150 mM KCl buffer significantly delayed CHX-induced apoptosis, suggesting that depolarization rather than Ca2+ stores depletion was the crucial event. Timing experiments revealed that depolarization within 12 min of CHX exposure significantly delayed apoptosis. Collectively, these observations suggest an early psi-sensitive step in the apoptosis pathway initiated by CHX. CHX exposure alone does not alter either resting PMN [free Ca] or psi; accompanying depolarization of plasma membrane (either electrochemically or via depletion of internal Ca2+ stores) delays CHX-induced apoptosis in a time-dependent manner.

Conductive choline transport by alveolar epithelial plasma membrane vesicles

Choline is an important substrate in alveolar epithelia for both surfactant production and cellular maintenance. The underlying mechanisms of uptake and sites of membrane transport remain uncertain. To test the hypothesis that choline transport occurs at the basolateral side of alveolar epithelia by both Na+-independent and -dependent mechanisms, plasma membrane vesicles were prepared from the apical and basolateral membranes of mature porcine type II pneumocytes. Choline+ transport was assayed by uptake of [3H]choline+ by enriched apical or basolateral vesicles. In the presence of imposed, inside-negative charge gradients, basolateral vesicles exhibited early overshoot of [3H]choline+ uptake unaffected by the presence or absence of external Na+ (541 +/- 53 vs 564 +/- 79 pmol/mg protein (NS)). High sensitivity to hemicholinium-3 was observed in the presence or absence of Na+. In the absence of inside-negative charge gradients, uptake was reduced 12-fold in the presence or absence of Na+, and external choline+ induced internal alkalization of acidified basolateral vesicles. Accumulative [3H]choline+ uptakes by apical vesicles in the presence or absence of inside-negative charge gradients and Na+ were insignificant. We conclude that predominant choline+ uptake by type II pneumocytes occurs at the basolateral membrane by Na+-independent, electrogenic choline+ conductance. The presence of electroneutral choline+/H+ exchange is suggested.

Sodium-coupled transport of glucose by plasma membranes of type II pneumocytes

Sodium-dependent absorption of alveolar fluid promotes efficient gas exchange. In animal models, alveolar glucose stimulates phlorizin-sensitive, Na(+)-dependent fluid absorption. It is hypothesized that Na+/glucose cotransporters are localized to apical membranes of type II pneumocytes. Enriched apical and basolateral plasma membrane vesicles were isolated from adult bovine type II pneumocytes. Uptakes of 22Na+ and [3H]glucose by enriched apical and basolateral vesicles were monitored over time. Following addition of external glucose (75 mM), 22Na+ uptake by mannitol-loaded, apically-enriched vesicles was significantly increased over controls. Substitution of interior-negative charge gradients for internally directed Na+ gradients increased glucose-dependent Na+ uptakes even greater. By contrast, external glucose did not significantly promote 22Na+ uptake by enriched basolateral vesicles. External Na+ (75 mM) significantly increased [3H]glucose uptakes by enriched apical vesicles with evidence of overshoot. Phlorizin (100 microM) inhibited both glucose-coupled 22Na+ uptakes and Na(+)-coupled [3H]glucose uptakes. These observations support localization of electrogenic, Na+/glucose cotransporters to enriched apical membranes of mature type II pneumocytes.

Sodium chloride cotransport at the basolateral membrane of type II pneumocytes

Current evidence indirectly supports the hypothesis that Na+/Cl- cotransport occurs at basolateral membranes of type II pneumocytes. To test this hypothesis, enriched apical and basolateral plasma membrane vesicles were prepared from adult bovine type II pneumocytes. Uptake of 22Na+ or 36Cl- by these vesicle populations was monitored over time. Using enriched basolateral vesicles, substitution of formate- for Cl- nearly eliminated 22Na+ uptake, and substitution of Tris+ for Na+ significantly reduced 36Cl- uptake. These observations of Cl(-)-dependent 22Na+ uptake and Na(+)-dependent 36Cl- uptake demonstrated coupling between Na+ and Cl- absorption at the basolateral membrane. Na+/Cl- cotransport inhibitors, furosemide (1 mM) and bumetanide (0.1 mM), also reduced 22Na+ and 36Cl- uptakes by enriched basolateral vesicles. By contrast, furosemide and bumetanide did not affect 22Na+ and 36Cl- uptakes by enriched apical vesicles. Collectively, these observations support localization of Na+/Cl- cotransport to the basolateral membranes of mature type II pneumocytes.

Alpha 1-adrenergic and muscarinic receptors in adult and neonatal rat type II pneumocytes

Binding characteristics of the alpha 1-adrenergic radioloigand [3H]prazosin, and the muscarinic cholinergic radioligand, [3H]quinuclidinyl benzilate, were determined both in intact cell preparations of rat alveolar type II pneumocytes (TIIPs) and in membrane preparations of rat lung tissue. Binding in adult and neonatal (< 24 h postnatal age) rats was also compared. Binding affinities for both receptor classes on TIIPs and whole lung membrane preparations alike did not vary significantly with age. In lung membrane preparations, the concentrations of both receptor classes were higher in neonates than adults. In TIIPs, the alpha 1-adrenergic receptor concentration was higher in neonates, but muscarinic receptor concentration was higher in adults. To begin investigation of the functional significance of these receptors, the effects of alpha 1-adrenergic and muscarinic agonists on intracellular calcium ion concentration ([Ca2+]i) were also measured. Both agonists induced consistent increases in [Ca2+]i, which were blocked by respective antagonists. These data indicate the presence of receptors on TIIPs for alpha 1-adrenergic and muscarinic agonists that may influence cellular function via modulation of [Ca2+]i.

Sodium/proton transport by apical membranes of type-II pneumocytes

Recent studies fail to confirm the coexistence of Na+ channels and Na+/H+ exchange at the apical membranes of lower airway epithelia. Availability of plasma membrane vesicles simplifies the investigation of membrane transport processes. Apical and basolateral plasma membrane vesicles of disrupted type-II pneumocytes were fractionated upon nonlinear, continuous sucrose gradients. To investigate sodium transport, 22Na+ uptake by apical membrane vesicles was assayed in the presence and absence of transmembrane sodium diffusion potentials. Interior-negative sodium diffusion potentials promoted 22Na+ uptake 1.5-fold. Internally-directed H+ gradients or NH+4 gradients inhibited 22Na+ uptake 40-50%. Amiloride (1-1000 microM) inhibited uptake 10-79%. To investigate H+ transport, decay of transmembrane pH gradients was monitored with pH probe acridine orange. In the presence or absence of externally-directed H+ gradients, external sodium promoted internal alkalinization, except in the presence of external amiloride. These observations of amiloride-sensitive, electrogenic Na+ uptake and amiloride-sensitive, electroneutral, Na+/H+ coupling indicate coexistence of Na+ channels and Na+/H+ exchange at the apical membrane of type-II pneumocytes.

Gestational age correlates with skin reflectance in newborn infants of 24-42 weeks gestation

Accurate gestational age determination is limited in very low birthweight infants using neurological and physical assessments. As one of the markers of intrauterine development, skin maturation is assessed qualitatively by pediatricians. Based on this observation, we hypothesize that skin reflectance relates directly to gestational age. Light was delivered and collected from the skin through a topically placed optical patch. Reflected light was detected by the spectrophotometer and corrected by an adjacent laptop computer to yield the true total diffuse reflectance as a function of wavelength between 380-820 nm. The calculated reflectance at 837 nm (R837) where it is independent of melanin, was determined by extrapolation from the reflectance at 650 and 750 nm. Sixty-four neonates of different races with gestational ages of 24-42 weeks were studied at 2-151 h of age. R837 was related exponentially to gestational age (GA) by the equation R837 = Rmax(1-exp[-(GA-G0)/tau]), where Rmax is the maximal value of R837, G0 is an apparent delay time before dermal scattering increases rapidly, and tau is a time constant, r = 0.88, p < 0.001. In summary, the extrapolated skin reflectance offers a quantitative and objective assessment of gestational age which is independent of melanin and sex.

Taurine-conjugated bile acids act as Ca2+ ionophores

The ionophoretic properties of several taurine-conjugated bile acids have been investigated in two experimental systems: in a two-phase bulk partitioning system and in proteoliposomes. In the former, a bile acid/Ca2+ complex was extracted into the bulk organic phase and had an experimental stoichiometry of 1.75. Extraction was specific for Ca2+ over Mg2+; Na+ and K+ did not compete with the extraction of Ca2+. In the second system, bile acids at concentrations as low as 5-100 molecules/vesicle lowered the steady-state Ca2+ gradient maintained by a reconstituted sarcoplasmic reticulum Ca(2+)-ATPase. The effect was not due to nonspecific membrane perturbation. In addition to releasing intravesicular Ca2+ in a transmembraneous process, bile acids caused partition of Ca2+/bile acid complexes into the hydrophobic core of the bilayer. In both experimental systems, the Ca2+ ionophoretic activity correlated well with the concentration and the hydrophobicity of the bile acid. Taurolithocholate was most active, with a significant effect measurable at 10 microM in either system. Since bile acid concentrations equal to those used in our experiments can occur in the blood in certain liver diseases, the results support the notion that bile acids can increase the intracellular Ca2+ concentration bypassing the regulatory systems that maintain cellular Ca2+ homeostasis.

Bile salt-induced intracellular Ca++ accumulation in type II pneumocytes

The pathogenesis of pneumonitis associated with meconium aspiration is poorly understood. To explore the possibility of pulmonary cytotoxicity in association with bile salt exposure and calcium accumulation, we compared cell viability, radiolabeled calcium accumulation, and intracellular [calcium] in the presence and absence of bile salts, chenodeoxycholate, and 3 beta-OH-5-cholenoate. We assessed viability of type II pneumocytes in culture by cell permeability to trypan blue dye, incorporation of leucine into cellular proteins, and cellular morphology. Intracellular calcium concentrations were monitored with fluorescent dye methodology. At micromolar concentrations, the above bile salts increased cell permeability by as much as 9-fold and decreased leucine incorporation by as much as 5-fold. Radiolabeled calcium accumulation increased by as much as 2.5-fold and intracellular [calcium] transiently increased by as much as 6-fold. Studies using bile salts extracted from meconium yielded similar results. Correlation of calcium accumulation to viability studies yielded a direct relationship with cell permeability and an inverse relationship with leucine incorporation. We speculate that bile salt-induced accumulation of intracellular calcium in lung cells may contribute to the pathogenesis of meconium aspiration pneumonitis.

Neurocristopathy syndrome: review of four cases

Aberrant embryologic development of the neural crest may clinically result in one of several patterns of malformation. Four examples of the neurocristopathy syndrome are described that collectively feature a very broad range of expression in these infants. Because of the many expressions, the syndrome may not be recognized. We believe that greater familiarity with the disorder will aid in the discovery of unsuspected anomalies and provide clues about predisposing etiologies.

Maternal-neonatal serum vitamin A concentrations

Prevention of neonatal vitamin A deficiency is related to the adequacy of maternal vitamin A stores. In this study we investigated maternal and cord serum vitamin A and retinol-binding protein (RBP) values in an Indian population including, for the first time, clinically vitamin A-deficient mothers. Twenty-eight maternal-neonatal pairs were selected from maternal cohorts of high socioeconomic status without clinical evidence of vitamin A deficiency (group I) and low socioeconomic status with conjunctival xerosis and Bitot's spots (group II). Maternal education, caloric and vitamin A intakes, weight, height, hemoglobin, and birth weight were significantly lower in group II. Serum vitamin A levels were significantly higher in group I mothers and newborns as were RBP levels in group I mothers. However, a significant difference between groups I and II in cord blood RBP was not observed. Upon correlation of maternal vitamin A levels with cord blood vitamin A levels, a logarithmic relationship was revealed, suggesting saturable transplacental transport of vitamin A.

Effect of bile acids on calcium efflux from isolated rat hepatocytes and perfused rat livers

The changes in intracellular Ca2+ concentration [( Ca2+]i) of hepatocytes induced by certain bile acids are biphasic: an initial increase is followed by a more gradual decrease. This latter decline in [Ca2+]i may be due to an efflux of Ca2+ across the plasma membrane. This hypothesis was tested by studying the effect of different bile acids on the efflux of 45Ca from preloaded rat hepatocytes and isolated perfused rat livers. The following bile acids were studied: cholic (C), ursodeoxycholic (UDC), chenodeoxycholic (CDC), and deoxycholic (DC) acids; their taurine (T) conjugates (TC, TUDC, TCDC, and TDC); and the taurine, sulfate (S), and glucuronide (Glu) derivatives of lithocholic acid (TLC, LS, TLS, and LGlu, respectively). At 0.3 mM, all bile acids except C, TC, TCDC, UDC, and TUDC significantly increased 45Ca efflux from preloaded hepatocytes without affecting cell viability. Dose-response studies revealed that the minimum effective concentration needed to induce 45Ca efflux was 0.06 mM for LS, 0.8 mM for TCDC, and 10 mM for TC. Efflux of 86Rb from preloaded hepatocytes was not significantly altered by 0.1 mM LS, indicating relative specificity for calcium. TDC and DC, but not TC, increased 45Ca efflux from preloaded perfused rat livers. These results showed that bile acids known to increase [Ca2+]i (CDC, DC, TDC, and TLC) also increased 45Ca efflux from hepatocytes and perfused livers and that efflux was also stimulated by LS, TLS, and LGlu. The extent of this efflux was related to the hydrophobicity of the steroid nucleus of the bile acid. It is speculated that bile acid-induced increases in [Ca2+]i activate the plasma membrane Ca2+ pump resulting in increased Ca2+ efflux.

Vitamin concentrations in very low birth weight infants given vitamins intravenously in a lipid emulsion: measurement of vitamins A, D, and E and riboflavin

Because total parenteral nutrition with vitamins added to the glucose-amino acid mixture is often associated with a reduction in blood levels of vitamin A (retinol) during the routine treatment of many very low birth weight (VLBW) infants (less than 1500 gm), and because retinol losses in the plastic delivery system can be prevented by adding the vitamins to an intravenous lipid emulsion, seven VLBW infants with a mean birth weight of 900 gm (range 450 to 1360 gm) were given 40% of a unit dose vial, per kilogram of body weight, of a multivitamin preparation (M.V.I. Pediatric) (280 micrograms retinol; 160 IU vitamin D; 2.8 mg tocopherol; 0.68 mg riboflavin) in a lipid emulsion, Intralipid. After treatment with the intralipid-vitamin mixture for 19 to 28 days, plasma vitamin A (retinol) concentrations increased significantly from 11.0 +/- 0.76 (mean +/- SEM) before intralipid to 19.2 +/- 0.97 micrograms/dl after the intralipid-vitamin mixture (p less than 0.01); 25-hydroxyvitamin D concentrations increased from an initial value of 12.6 +/- 2.6 to 20.2 +/- 1.9 mg/dl (p less than 0.01); alpha-tocopherol concentrations increased from an initial value of 0.31 +/- 0.06 to 2.44 +/- 0.13 mg/dl (p less than 0.01); and riboflavin levels increased from 64.1 +/- 7.8 ng/ml to concentrations between 20 and 100 times the initial level. Erythrocyte riboflavin levels increased from 71.8 +/- 14 initially to 166 +/- 41 ng/gm hemoglobin, and erythrocyte flavin-adenine dinucleotide levels increased similarly from 972 +/- 112 initially to 2005 +/- 294 ng/gm hemoglobin. These results show that the addition of M.V.I. Pediatric to Intralipid decreases the extensive in vivo loss of retinol and is associated with an increase in plasma retinol concentrations in VLBW infants. The daily doses of vitamins D (160 IU/kg) and E (2.8 mg/kg) appear sufficient, but the dose of vitamin A (280 micrograms/kg) is insufficient to raise blood levels of all infants into the normal range. The current dose of riboflavin is excessive and may be harmful.

Intestinal absorption of bile acid glucuronides in rats

While the intestinal absorption of taurine, glycine, and sulfate conjugates of bile acids has been studied extensively, nothing is known about the absorption of bile acid glucuronides. In the present study, the intestinal phase of the enterohepatic circulation of two bile acid glucuronides was examined. [3 beta-3H]cholic acid 3-O-beta-D-glucuronide or [3 beta-3H]lithocholic acid 3-O-beta-D-glucuronide was perfused through isolated segments of ileum or jejunum with intact blood supply in rats prepared with a biliary fistula. [14C]Taurocholic acid was perfused simultaneously with each glucuronide to compare glucuronide absorption with that of an actively transported bile acid. Intestinal absorption was determined by measuring the rate of secretion of labeled bile acid in bile. The absorption of [3H]cholic acid glucuronide by the ileum and jejunum was one fortieth and one eighth, respectively, that of [14C]taurocholic acid. Comparison of the two glucuronides show that [3H]lithocholic acid glucuronide absorption was 18 and 10 times greater than [3H]cholic acid glucuronide absorption from the jejunum and ileum, respectively. Collectively, the above observations suggest that glucuronidation of bile acids markedly reduces absorption from the small intestine.

Bile salt-induced calcium fluxes in artificial phospholipid vesicles

The ionic permeability of selected biological membranes is increased by bile salts. To examine changes in calcium permeability during the exposure of artificial membranes to bile salts, we investigated calcium uptake by unilamellar and multilamellar phospholipid vesicles. In the presence of 750 microM taurodeoxycholate, uptake of radiolabelled calcium by unilamellar vesicles increased 2.5-fold over control values. Calcium uptake by multilamellar vesicles as measured with a free calcium indicator, arsenazo III, increased 2.2- or 21-fold in the presence of 60 microM lithocholate or 3 beta-hydroxy-5-cholenoate, respectively. Results were directly influenced by experimental variables such as bile salt hydrophobicity, external calcium concentration, and the bile salt/lipid molar ratio. Observed membrane solubilization was minimal despite increased calcium permeability. Comparison of radiolabelled calcium uptake with radiolabelled sodium or radiolabelled rubidium uptake indicated that bile salt-dependent calcium uptake was 60-140-times greater than bile salt-dependent uptake of either monovalent cation. In an effort to delineate forces affecting calcium translocation, vesicles were exposed either to valinomycin, which induced an electrochemical gradient across the membrane, or to nigericin, which induced a proton gradient. Exposure to valinomycin minimally influenced bile salt-induced calcium uptake while exposure to nigericin significantly promoted uptake by 40-70%. The results suggest that bile salts promote calcium uptake by a mechanism which may be similar to those of other carboxylic ionophores.

Intracranial hemorrhage in term or near-term newborns with persistent pulmonary hypertension

To substantiate the clinical impression of an increased incidence of intracranial hemorrhage (ICH) in term and near-term infants with persistent pulmonary hypertension (PPH), a retrospective chart review of 35 affected patients was performed. ICH was diagnosed in 40 percent of the patients. Multiple regions of the brain were affected; in many patients, at more than one location. In addition, 43 percent of ICH victims had hemorrhages of the type associated with periventricular bleeding in preterm newborns. Of multiple obstetric and neonatal factors analyzed, many of which are identified risk factors for periventricular hemorrhage, only thrombocytopenia (p = 0.02) was significantly associated with ICH. We conclude that the risk of ICH in newborns with PPH is significant and warrants consideration by clinicians caring for this population. Risk factors (except thrombocytopenia) previously implicated in other types of neonatal ICH, particularly periventricular hemorrhage, do not significantly correlate with ICH in infants with PPH.

Bile salts induce calcium uptake in vitro by human erythrocytes

At high concentrations, bile salts induce hemolysis by comicellization of lipid components of the cell membrane. However, bile salts are also associated with hemolysis at lower concentrations by mechanisms which have not been characterized. To investigate the possibility that bile salts promote calcium uptake by red blood cells and that bile salt-associated hemolysis is, in part, calcium-mediated, calcium uptake by red blood cells was measured in the presence of individual bile salts, and hemolysis dependence upon calcium availability was examined. Washed human red blood cells with or without ATP depletion were incubated with 1 mM CaCl2 and tracer amounts of 45CaCl2 in the presence of selected bile salts at concentrations (0.01 to 0.3 mM) reported to be below critical micellar concentrations. Calcium uptake (defined for the purposes of this study as 45Ca retained in red blood cells) was monitored over 5 hr, after which hemolysis and membrane phospholipid content were determined. The presence of bile salts stimulated calcium uptake 4- to 25-fold--the magnitude of which was partly related to the lipid solubility of the bile salts. ATP depletion or exposure to trifluoperazine, procedures which inhibit calcium pump activity in red blood cells, enhanced bile salt-induced calcium uptake relative to controls. The percentage of associated hemolysis (2 to 14%) at the end of 5 hr correlated directly with the observed calcium uptake. Removal of calcium from the extracellular space reduced hemolysis in the presence of bile salts to control levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Cellular mechanisms of cholestasis

Concepts regarding the pathogenesis of cholestasis continue to evolve as investigational techniques improve and molecular mechanisms of bile formation are clarified. With the accumulation of information it is becoming increasingly evident that cholestasis results from not one but multiple disturbances in the sequence of events responsible for bile production. In addition to the inhibition of bile flow attributable to initiating events, cholestasis itself may inhibit bile flow by altering the intra- and extracellular environments of liver cells. Many questions about cholestasis remain unanswered, but future directions for research are suggested by the information currently available.

Lithocholate glucuronide is a cholestatic agent

Lithocholic acid and its taurine, glycine, and sulfate derivatives are potent cholestatic agents. Lithocholate glucuronide is present in the plasma and urine of patients with cholestatic syndromes, but little is known of its metabolism, excretion, and cholestatic potential. [3 beta-3H]lithocholate 3-O-beta-D-glucuronide was synthesized, and chemical and radiochemical purity were established. The aqueous solubility of lithocholate glucuronide was determined and found to be greater than that of lithocholic acid or several of its derivatives. In the range of concentrations examined, calcium ions precipitated lithocholate glucuronide stoichiometrically. The material was administered to rats prepared with an external biliary fistula. When 17-25 micrograms quantities were administered, 89.1 +/- 4.5% (mean +/- SEM) of the radiolabel was secreted in bile within the first 20 h after administration, the major fraction being secreted in less than 20 min. Four-fifths of the radiolabeled material in bile was the administered unaltered parent compound, while a minor fraction consisted of a more polar derivative(s). We showed that increasing biliary concentrations of more polar derivatives were observed with milligram doses of [3H]lithocholate glucuronide, and with time after the administration of these loading doses. Milligram doses of [3H]lithocholate glucuronide resulted in partial or complete cholestasis. When induced cholestasis was partial, secretion in bile remained the primary excretory route (82.5-105.6% recovery in bile), while, when complete cholestasis was induced, wide tissue distribution of radiolabel was observed. Cholestasis developed rapidly during infusion of [3H]lithocholate glucuronide. Bile flow was diminished within 10-20 min of the start of an infusion of 0.05 mumol, 100 g-1 body weight, minute-1, administered concomitantly with an equimolar infusion of taurocholate. The results establish that lithocholate glucuronide exerts cholestatic effects comparable to those exerted by unconjugated lithocholic acid.

Calcium binding by lithocholic acid derivatives

Lithocholic acid (LCA) and its sulfate (LCS) and glucuronide (LCG) derivatives are potent cholestatic agents. During the course of LCG-induced cholestasis in rats, calcium (Ca) salts of LCG precipitate in bile. To characterize the affinity of bile salts for Ca, solutions of selected bile salts were titrated with Ca. Apparent equilibrium constants (KcaBS) were determined from the unbound Ca ion concentrations that were measured spectrophotometrically with metallochromic indicators antipyrylazo III or murexide or with a Ca-selective electrode. KCaBS values were 1.12 +/- 0.04 X 10(-4) M for LCS, 2.88 +/- 0.26 X 10(-4) M for LCG, 3.09 +/- 0.21 X 10(-4) M for LCA, 1.93 +/- 0.07 X 10(-3) M for taurocholic acid (TC), 2.69 +/- 0.08 X 10(-3) M for glycocholic acid (GC), and 6.07 +/- 0.27 X 10(-3) M for taurolithocholic acid sulfate (TLCS). The KCaBS for LCG measured by a Ca-selective electrode under identical conditions was 5.53 +/- 2.75 X 10(-4) M. Comparing relative cholestatic potential with affinity for Ca, cholestatic bile salts LCS, LCG, and LCA bind Ca 10-60 times more avidly than TC, GC, and TLCS. At the unbound Ca ion concentrations of serum or bile (approx 1 mM), only LCS, LCG, and LCA would be expected to bind significant amounts of Ca.

Endocarditis in high-risk neonates

The clinical spectrum of neonatal endocarditis, including bacterial and nonbacterial types, is examined in five case reports that were drawn from nursery experiences over a recent 2-year period. In contrast to previous reports of 100% mortality from neonatal endocarditis, one patient survived. Changing heart murmur and hematuria were most frequently associated with bacterial and nonbacterial endocarditis in four of the five cases. Pulmonary hypertension, thrombocytopenia, and coagulopathy were also associated with nonbacterial endocarditis. Echocardiograms were performed on four of the patients; only one was suggestive of endocarditis. Staphylococcus aureus was isolated from both cases of bacterial endocarditis, including the single survivor. Thus, it is suggested that the initial antibiotic coverage of any neonate with the clinical syndrome of sepsis, hematuria, and a heart murmur include antistaphylococcal coverage for the possibility of bacterial endocarditis.

Hospitalization of adolescents: collecting the data base. Variations and implications

A survey of 2208 adolescents (aged 12 through 18 years) hospitalized during 1977 identified variations in data-base development and unrecognized health problems. Forty-eight percent were admitted to obstetrics and gynecology, 29% to surgery, 13% to pediatrics/internal medicine combined, and 10% to psychiatry. Historical, physical, and laboratory data bases and diagnoses were examined from 325 records. All records included a history of present illness and blood pressure, and most included a past medical and family history. Excluding pediatric records, a minority of records included social, immunization, school, or perinatal histories. Pediatric records were lacking in histories of alcohol or tobacco use. Most records lacked dietary or drug-abuse histories. A majority of records contained growth parameters, hemoglobin, urinalysis, and chest x-ray. Despite a high prevalence of anemia, the diagnosis was infrequently recorded. This survey suggests that clinical departments collect data on sick adolescents in differing ways--none of which seems optimal. Clinical departments should examine their training programs regarding the collection and interpretation of the data base in order to provide optimal care for hospitalized adolescents.