CFTR pharmacological modulators: A great advance in cystic fibrosis management

Cystic fibrosis is a severe monogenic disease that affects around 7400 patients in France. More than 2100 mutations in the cystic fibrosis conductance transmembrane regulator (CFTR), the gene encoding for an epithelial ion channel that normally transports chloride and bicarbonate, lead to mucus dehydration and impaired bronchial clearance. Systematic neonatal screening in France since 2002 has enabled early diagnosis of cystic fibrosis. Although highly demanding, supportive treatments including daily chest physiotherapy, inhaled aerosol therapy, frequent antibiotic courses, nutritional and pancreatic extracts have improved the prognosis. Median age at death is now beyond 30 years. Ivacaftor was the first CFTR modulator found to both reduce sweat chloride concentration and improve pulmonary function in the rare CFTR gating mutations. Combinations of modulators such as lumacaftor + ivacaftor or tezacaftor + ivacaftor were found to improve pulmonary function both in patients homozygous for the F508del mutation characterized by the lack of CFTR protein and those heterozygous for F508del with minimal CFTR activity. The triple combination of ivacaftor + tezacaftor + elexacaftor was recently shown to significantly improve pulmonary function and quality of life, to normalize sweat chloride concentration, and to reduce the need for antibiotic therapy in patients with at least one F508del mutation (83% in France). These impressive data, however, need to be confirmed in the long term. Nevertheless, it is encouraging to hear treated patients testify about their markedly improved quality of life and to observe that the number of lung transplants for cystic fibrosis decreased dramatically in France after 2020, despite the COVID pandemic, with no increase in deaths without lung transplant.

Cardiac troponin elevation and mortality in takotsubo syndrome: new insights from the International Takotsubo (InterTAK) registry

Background/Introduction

Cardiac biomarker elevations are frequently observed in Takotsubo syndrome (TTS). The clinical relevance of cardiac troponin (cTn) elevations in TTS patients remains uncertain and threshold values indicating clinically relevant myocardial injury are unknown.

Purpose

This study sought to investigate the role of cTn elevations in mortality prediction of patients with TTS.

Methods

A total of 2,938 patients enrolled in the prospective International Takotsubo (InterTAK) Registry from January 2011 to February 2020 and with available data on baseline and peak cTn levels were included in the analysis. The threshold at which myocardial injury drives mortality was identified using restricted cubic spline analysis.

Results

Out of 2,938 patients, 222 (7.6%) patients died during 1-year follow-up. A more than 28.8-fold increase of cTn above the upper reference limit was identified as threshold for clinically relevant myocardial injury. Mortality at 1 year was significantly higher in patients with clinically relevant myocardial injury than in those without (Log Rank p<0.001, Figure 1). The presence of clinically relevant myocardial injury was significantly associated with an increased risk of mortality at 5 years (adjusted HR 1.58, 95% CI 1.18–2.12, p=0.002). Clinically relevant myocardial injury was related to 5-year mortality in patients with apical TTS (adjusted HR 1.57, 95% CI 1.21–2.03, p=0.001), with presence of physical stressors (adjusted HR 1.60, 95% CI 1.22–2.11, p=0.001), and with absence of emotional stressors (adjusted HR 1.49, 95% CI, 1.17–1.89, p=0.001).

Conclusions

This study for the first time determined a troponin threshold for the identification of TTS patients at excess risk of mortality. These findings advance risk stratification in TTS and assist in identifying patients in need for close monitoring and follow-up.

Funding Acknowledgement

Type of funding sources: Foundation.

Body weight and mortality in takotsubo syndrome: insights from the International Takotsubo (InterTAK) registry

Background/Introduction

The obesity paradox has been described in different cardiovascular conditions. Data on the association between obesity and outcomes in patients with Takotsubo syndrome (TTS) are lacking.

Purpose

The aim of this study was to determine the relation of body weight to mortality in TTS patients.

Methods

Patients enrolled in the International Takotsubo (InterTAK) Registry from January 2011 to July 2021 and with available data on BMI were included in the analysis. Patients were stratified according to BMI (underweight, <18.5 kg/m2; normal weight, 18.5–24.9 kg/m2; overweight, 25.0–29.9 kg/m2; obese, 30.0–34.9 kg/m2; and very obese, ≥35.0 kg/m2). The primary endpoint was mortality at 1 year.

Results

Of the 2'707 patients, 222 (8.2%) were underweight, 1340 (49.5%) of normal weight, 759 (28.0%) overweight, 268 (9.9%) obese, and 118 (4.4%) very obese. Mortality at 1 year as a function of BMI with 95% confidence interval is given in Figure 1. Mortality at 1 year was 11.3%, 6.9%, 5.5%, 4.9%, and 9.3% in underweight, normal weight, overweight, obese, and very obese patients (p=0.02, Figure 2). Being overweight or obese was significantly associated with a lower mortality at 1 year (HR 0.70, 95% CI 0.51–0.96, p=0.03), and associations remained significant after multivariable adjustments (adjusted HR 0.67, 95% CI 0.46–0.97, p=0.03). Associations were observed when including patients without emotional stressors (adjusted HR 0.64, 95% CI 0.43–0.94, p=0.02), but not when including those with emotional stressors (adjusted HR 1.14, 95% CI 0.30–4.27, p=0.85).

Conclusion

A U-shaped mortality curve across BMI categories was observed in TTS patients, with lowest mortality rates in obese patients. These observations provide first evidence for the existence of the obesity paradox in TTS.

Funding Acknowledgement

Type of funding sources: Foundation.

Assessment of Artificial Intelligence in Echocardiography Diagnostics in Differentiating Takotsubo Syndrome From Myocardial Infarction

Importance

Machine learning algorithms enable the automatic classification of cardiovascular diseases based on raw cardiac ultrasound imaging data. However, the utility of machine learning in distinguishing between takotsubo syndrome (TTS) and acute myocardial infarction (AMI) has not been studied.

Objectives

To assess the utility of machine learning systems for automatic discrimination of TTS and AMI.

Design, Settings, and Participants

This cohort study included clinical data and transthoracic echocardiogram results of patients with AMI from the Zurich Acute Coronary Syndrome Registry and patients with TTS obtained from 7 cardiovascular centers in the International Takotsubo Registry. Data from the validation cohort were obtained from April 2011 to February 2017. Data from the training cohort were obtained from March 2017 to May 2019. Data were analyzed from September 2019 to June 2021.

Exposure

Transthoracic echocardiograms of 224 patients with TTS and 224 patients with AMI were analyzed.

Main Outcomes and Measures

Area under the receiver operating characteristic curve (AUC), accuracy, sensitivity, and specificity of the machine learning system evaluated on an independent data set and 4 practicing cardiologists for comparison. Echocardiography videos of 228 patients were used in the development and training of a deep learning model. The performance of the automated echocardiogram video analysis method was evaluated on an independent data set consisting of 220 patients. Data were matched according to age, sex, and ST-segment elevation/non-ST-segment elevation (1 patient with AMI for each patient with TTS). Predictions were compared with echocardiographic-based interpretations from 4 practicing cardiologists in terms of sensitivity, specificity, and AUC calculated from confidence scores concerning their binary diagnosis.

Results

In this cohort study, apical 2-chamber and 4-chamber echocardiographic views of 110 patients with TTS (mean [SD] age, 68.4 [12.1] years; 103 [90.4%] were female) and 110 patients with AMI (mean [SD] age, 69.1 [12.2] years; 103 [90.4%] were female) from an independent data set were evaluated. This approach achieved a mean (SD) AUC of 0.79 (0.01) with an overall accuracy of 74.8 (0.7%). In comparison, cardiologists achieved a mean (SD) AUC of 0.71 (0.03) and accuracy of 64.4 (3.5%) on the same data set. In a subanalysis based on 61 patients with apical TTS and 56 patients with AMI due to occlusion of the left anterior descending coronary artery, the model achieved a mean (SD) AUC score of 0.84 (0.01) and an accuracy of 78.6 (1.6%), outperforming the 4 practicing cardiologists (mean [SD] AUC, 0.72 [0.02]) and accuracy of 66.9 (2.8%).

Conclusions and Relevance

In this cohort study, a real-time system for fully automated interpretation of echocardiogram videos was established and trained to differentiate TTS from AMI. While this system was more accurate than cardiologists in echocardiography-based disease classification, further studies are warranted for clinical application.

Evaluation of frequency of paediatric oral liquid medication dosing errors by caregivers: amoxicillin and josamycin

OBJECTIVE

To study reconstitution and preparation dosing errors of liquid oral medications given by caregivers to children.

METHODS

A prospective observational study was carried out in the departments of general paediatrics and emergency paediatrics at the Robert-Debré Children's University Hospital. An interview with caregivers involved (1) practical reconstitution and preparation of an oral liquid medication from a prescription drawn at random (amoxicillin (Clamoxyl, dosing spoon) or josamycin (Josacine, dose-weight pipette)) and (2) a questionnaire about their use.

RESULTS

One hundred caregivers were included. Clamoxyl and Josacine were incorrectly reconstituted in 46% (23/50) and 56% (28/50) of cases, respectively, with a risk of underdosing of Clamoxyl (16/23) and overdosing of Josacine (23/28). Dose preparation with the dosing spoon was incorrect in 56% of cases, and in 10% of cases with the dose-weight pipette. Female sex, native French speaker, and age were significantly associated with correct reconstitution. Male sex and medication were significantly associated with correct preparation.

CONCLUSIONS

This study highlights the high incidence of errors made by caregivers in reconstituting and preparing doses of these liquid oral medicines, which are associated with considerable risks of over- and underdosing. Factors associated with these errors have been identified which could help health professionals to optimise their strategy for educating families about the use of liquid oral medications and the need to check that they understand these instructions.

Sensitivity and specificity of a rapid influenza diagnostic test in children and clinical utility during influenza A (H1N1) 2009 outbreak

INTRODUCTION

The influenza A (H1N1) 2009 outbreak caused death and a disruption of public health services. Rapid influenza diagnostic tests (RIDT) could be helpful to ease the triage of patients and prevent an overload of emergency and laboratory facilities.

OBJECTIVES

To compare the sensitivity and specificity of the Clearview Exact Influenza A&B test and real-time reverse transcription(RT)-PCR to detect influenza A (H1N1) 2009 in a paediatric emergency department of a paediatric teaching hospital in Paris, France.

METHODS

76 children with an influenza-like illness and either severe symptoms or an underlying medical condition were prospectively recruited between July 2009 and October 2009. RIDT and RT-PCR were simultaneously performed and compared.

RESULTS

Among 39 influenza A (H1N1) 2009 RT-PCR-positive children (median age 5 years), 23 Clearview Exact Influenza A&B tests were positive. Sensitivity was 59% (95% CI 42.2 to 74) and specificity was 94.6% (95% CI 80.5 to 99.1).

CONCLUSIONS

This study shows a sensitivity of RIDT of 59%, in agreement with other prospective studies, which could be useful in clinical practice for diagnosis influenza A (H1N1) 2009 in children. In outbreaks of a high prevalence, such as the 2009 outbreak, this test can help to prevent an overload of public health services.

Role of tyrosine phosphatase in the modulation of pulmonary vascular tone

In the vascular system, synthesis of the potent vasodilator nitric oxide (NO) is tightly regulated by the constitutively expressed endothelial NO synthase (eNOS). Activity of eNOS is controlled by Ca2+/calmodulin and various seryl/threonyl protein kinases. Less is known about the importance of phosphorylation and dephosphorylation of tyrosyl residues. Therefore the role of tyrosine phosphatase on the modulation of isolated rat pulmonary artery tone has been assessed. Inhibition of tyrosine phosphatase by sodium orthovanadate (SOV, 1x10(-6) M) significantly: 1) increased phenylephrine-induced vasoconstriction and 2) decreased endothelium-dependent relaxation to acetylcholine, but had no effect on endothelium-independent relaxation to the NO donor, sodium nitroprusside. In phenylephrine-precontracted pulmonary arterial rings, SOV (1x10(-7)-1x10(-5) M) had no effect on vascular tone but significantly relaxed rings which were pretreated with the NO-synthase inhibitor, N(omega)-nitro-L-arginine-methyl ester (L-NAME). SOV-induced relaxation in the presence of L-NAME was, however, abolished by glibenclamide. In conclusion, inhibition of tyrosine phosphatase altered pulmonary vascular tone by increasing vasoconstrictor response to phenylephrine and decreasing endothelium-dependent relaxation to acetylcholine. Furthermore, the tyrosine phosphatase inhibitor, sodium orthovanadate, exhibited original vasodilator properties which were only observed when nitric oxide synthesis was inhibited. Thus a new pathway involving the inhibitory effect of nitric oxide on a glibenclamide-sensitive diffusible relaxing factor, that might play an important role in the control of pulmonary vascular tone is described.

Expression analysis of ruminant α-lactalbumin in transgenic mice: Developmental regulation and general location of importantcis-regulatory elements

The bovine alpha-lactalbumin transgene with 750 bp and 336 bp of the 5' and 3' flanking region, respectively, is developmentally regulated as its endogenous counterpart in transgenic mice. Comparative expression analysis of three 5'-shortened constructs suggests that the region -477/-220 contains important cis-acting transcriptional elements. The level of expression of a long caprine alpha-lactalbumin transgene encompassing 8.5 kb and 9.5 kb of the 5' and 3' flanking region, respectively, was higher but still unrelated to the copy number. Expression of the transgenes and of endogenous milk-protein genes was tissue-specific. In contrast with a recent report, only low amounts of the relevant mRNA were detected in some skin samples, which suggests a possible contamination by mammary tissue.

[Meningococcal purpura fulminans: untoward result of genetic polymorphism?]

Despite significant progress in intensive care medicine, the mortality of septic shock has not changed in recent years. Early recognition of subtle signs in favor of meningococcal sepsis, early antibiotic treatment, and aggressive hemodynamic support remains the cornerstone of therapy of severe meningococcal shock in children. Recent work has emphasized the role of genetic polymorphisms in various systems to explain the most severe cases: anti-inflammatory cytokine profile IL-10/TNF-alpha, elevated levels of plasminogen activator inhibitor type-1, variants of the gene for mannose-binding lectin complement pathway. This may explain the disillusionment of pediatric intensivists, and the general failure of immunotherapy for sepsis. Reasonable hope lies upon new meningococcal vaccines.

Uncertainties about the use of inhaled nitric oxide in preterm infants

Respiratory failure in the premature neonate is frequently complicated by pulmonary hypertension. When conventional therapies including administration of exogenous surfactant, conventional mechanical ventilation or high-frequency oscillatory ventilation using an appropriate high-volume strategy have failed, one should assess the pulmonary circulation status with colour-coded Doppler echocardiography. There is now considerable evidence that the regulation of foetal and postnatal pulmonary circulation occurs via nitric oxide (NO), and that persistent pulmonary hypertension of the neonate may be related to a relative deficiency in NO release. Low-dose (10-20 ppm), short-duration (1-2 d) inhaled NO has generally been shown to improve the oxygenation and relieve pulmonary hypertension in premature neonates with severely hypoxaemic respiratory failure. Whether this therapy (eventually prolonged >1-3 wk?) would improve survival and lessen morbidity (e.g. intracranial haemorrhage and chronic lung disease) remains to be proven by appropriately designed controlled trials. Until these issues can be clarified, NO therapy for premature neonates should be still considered as an experimental drug, and its use restricted to clinical studies.

[Prolonged length of stays in pediatric intensive care. Retrospective study of 100 stays]

New issues have arisen in pediatric intensive care units, especially concerning long-stay patients. The aims of the present study were to describe the etiologic factors of these long-stay patients and to recognize the comorbidities.

MATERIAL AND METHODS

Ninety-five patients who had a total of 100 hospitalizations of more than 30 days were admitted to the pediatric intensive care unit at Robert-Debre Hospital during a 3-year period (1993-1995); this accounted for 9.1% of total admissions. We retrospectively reviewed these 100 long-stay hospitalizations.

RESULTS

Most of these patients were newborns (65%). Patients with severe congenital anomalies (44 patients) and very premature infants (26 patients) constituted the majority of long-stay patients. The mean duration of mechanical ventilation for the 95 patients was 110 days (ranges 17-789 days). Two factors of comorbidity were found: gastroesophageal reflux (41% of cases) and nosocomial infections (89% of cases).

CONCLUSION

In order to prevent long stays, pediatric intensive care units must be directed toward these factors.

ET(A)-receptor blockade and ET(B)-receptor stimulation in experimental congenital diaphragmatic hernia

The aim of this study was to assess the role of nitric oxide (NO) and endothelin (ET)-1 in the pathophysiology of persistent pulmonary hypertension of the newborn in fetal lambs with a surgically created congenital diaphragmatic hernia (CDH). The pulmonary vascular response to various agonists and antagonists was assessed in vivo between 128 and 132 days gestation. Age-matched fetal lambs served as control animals. Control and CDH lambs had similar pulmonary vasodilator responses to acetylcholine, sodium nitroprusside, zaprinast, and dipyridamole. The ET(A)-receptor antagonist BQ-123 caused a significantly greater pulmonary vasodilatation in CDH than in control animals. The ET(B)-receptor agonist sarafotoxin 6c induced a biphasic response, with a sustained pulmonary vasoconstriction after a transient pulmonary vasodilatation that was not seen in CDH animals. We conclude that the NO signaling pathway in vivo is intact in experimental CDH. In contrast, ET(A)-receptor blockade and ET(B)-receptor stimulation significantly differed in CDH animals compared with control animals. Imbalance of ET-1-receptor activation favoring pulmonary vasoconstriction rather than altered NO-mediated pulmonary vasodilatation is likely to account for persistent pulmonary hypertension of the newborn in fetal lambs with a surgically created CDH.

Maturational changes of endothelial vasoactive factors and pulmonary vascular tone at birth

The aim of this study was to determine which endothelial factors were involved in the decrease of pulmonary vascular resistance at birth, and how they changed with maturation. Response of intrapulmonary artery rings precontracted with prostaglandin F2alpha were studied from piglets aged <2 h, 2-3 day, 10 day and adult pigs for pharmacological responses to acetylcholine (ACh) and cromakalim (CMK) in the presence and the absence of the nitric oxide synthase (NOS) inhibitor, N(omega)-nitro-L-arginine (L-NA), the adenosine triphosphate sensitive potassium (K(ATP)) channel blocker, glibenclamide and the endothelin (ET)-A receptor antagonist, BQ123. In situ hybridization and immunochemistry studies were performed in lung tissues of the same animals in order to determine the expression of NOS and ET. There was a small contractile effect of ACh in the newborn. Relaxation to ACh, which was blocked by L-NA and reduced by glibenclamide, only appeared from the age of 3 days. The significantly greater relaxation to CMK in rings without endothelium (p<0.05) was abolished by BQ123 in the newborn, and then disappeared by 2 days of age. Glibenclamide had a greater inhibitory effect on relaxation induced by CMK at 10 days than in the newborn and 2 days old piglets. NOS expression was low in pulmonary arteries of the newborn and increased by 2 days of age whereas the converse was seen with ET expression. It is concluded that: 1) relaxant response to acetylcholine was absent at birth and appeared at 2 days; 2) the reduced relaxant response to cromakalin in rings with endothelium at birth could be blocked by BQ123; and 3) the expression of endothelin decreased whereas the expression of nitric oxide synthase increased from birth to 2 days of age.

A single nucleotide deletion resulting in a premature stop codon is associated with marked reduction of transcripts from a goat beta-casein null allele

A null beta-casein allele (CSN2O) was investigated in Creole and Pyrenean goats producing milk devoid of beta-casein (CSN2). Northern blot analyses of total mammary RNA showed much lower amounts of CSN2 transcripts that were similar in size to the wild-type counterpart. The amount of CSN2O mRNA was roughly 5% of the amount of mRNA obtained at the same age and stage of lactation from CSN2A/A goats. Comparative sequence analyses of full-length CSN2O and CSN2A cDNAs showed that both alleles were of similar size, but allele CSN2O had a one-nucleotide deletion in the 5' end of exon 7, which introduces a premature stop codon. The open reading frame of allele CSN2O encodes a shortened polypeptide of 72 amino acids, compared to 223 amino acids for caprine pre beta-casein A. Comparative analyses of RT-PCR products suggested that alleles CSN2O and CSN2A might also differ in the amount and relative ratio of minor deleted CSN2 transcripts. The lower amount of CSN2O mRNA was associated with the occurrence of the premature stop codon which may mediate a rapid decay of CSN2O mRNA and promote skipping of nucleotide stretches containing premature nonsense triplets.

Vitamin A decreases the incidence and severity of nitrofen-induced congenital diaphragmatic hernia in rats

Congenital diaphragmatic hernia (CDH) is a major cause of refractory respiratory failure in the newborn. Pulmonary hypoplasia often limits survival. Vitamin A (Vit A) is an important signal for lung growth. We hypothesized that antenatal treatment with Vit A would stimulate lung growth and decrease mortality in experimental CDH induced in rats by ingestion of the herbicide nitrofen (2, 4-dichlorophenyl-p-nitrophenyl ether). Nitrofen was administered to pregnant rats on day 12 of gestation (term 22 days). Rats were assigned to five groups: three groups received one dose of oral antenatal Vit A (15,000 IU) before (day 10), concomitant with (day 12), or after (day 14) nitrofen administration; one group received only nitrofen; and a control group received vehicle (olive oil). The incidence of CDH was markedly lower in all groups receiving Vit A (day 10, 44%; day 12, 20%; and day 14, 40%) compared with the nitrofen-treated group (84%; P < 0.05). The 72-h survival was higher in all 3 Vit A-treated groups (day 10, 40%; day 12, 58%; and day 14, 70%) compared with the nitrofen-treated group (16%; P < 0.05). Lung-to-body weight ratio and radial saccular count were significantly increased by Vit A. Antenatal treatment with Vit A lowers the incidence and severity of experimental CDH and increases lung growth and maturation.

Position-independent and copy-number-related expression of a goat bacterial artificial chromosome alpha-lactalbumin gene in transgenic mice

A bacterial artificial chromosome goat insert comprising the alpha-lactalbumin-encoding transcription unit with approximately 150 and 10 kb of 5'- and 3'-flanking sequences, respectively, was micro-injected into mouse eggs. In six out of seven transgenic lines, the level of mammary tissue- and stage-specific expression was position-independent and copy-number-dependent. The exogenous alpha-lactalbumin yield, about 0.8 mg/ml of milk per copy, compared favourably with the alpha-lactalbumin content of mouse and goat milks, about 0.8 and >1 mg/ml, respectively. This suggests that the insert contains most if not all of the cis-acting elements involved in the full and specific expression of the goat alpha-lactalbumin gene and opens up opportunities to use this vector to target expression of foreign genes in the lactating mammary gland of transgenic animals. The transgene was silent in the seventh line for an unknown reason.

Use of doxycycline-controlled gene expression to reversibly alter milk-protein composition in transgenic mice

A reverse tetracycline transactivator-encoding cDNA under the control of the mammary specific beta-lactoglobulin promoter was linked to a bovine alpha-lactalbumin transcription unit driven by a reverse tetracycline-controlled transactivator/doxycycline-inducible human cytomegalovirus promoter. The construct was microinjected into eggs from alpha-lactalbumin-deficient mice. These mice produce a highly viscous lactose-free milk and have a shortened lactation period. Mice from three out of the nine transgenic lines investigated expressed reverse tetracycline-controlled transactivator mRNA in their lactating mammary glands at levels detectable by Northern analysis. Following doxycycline addition to the drinking water, lactation was fully restored in animals from the three lines. Doxycycline removal resulted in a reversal of phenotype. The observed mammary-specific and high expression of the doxycycline inducible reporter gene (up to 5.2 mg of recombinant alpha-lactalbumin.mL-1 of milk, i.e. up to 13-fold induction) opens up exciting prospects to use the tetracycline system to study the development and functioning of the mammary gland, and to control the production level of active pharmaceutical proteins in the milk of transgenic animals.

Dypiridamole, a cGMP phosphodiesterase inhibitor, transiently improves the response to inhaled nitric oxide in two newborns with congenital diaphragmatic hernia

INTRODUCTION

Congenital diaphragmatic hernia (CDH) remains a frustrating cause of respiratory failure associated with persistent pulmonary hypertension of the newborn (PPHN). Although inhaled nitric oxide (iNO) is effective in many infants with PPHN, it often fails to improve oxygenation in infants with CDH. As the increase in vascular smooth muscle cyclic guanosine monophosphate (cGMP) in response to iNO may be impeded by increased phosphodiesterase type-V (PDE-V) activity, it has been suggested that PDE-V blockade potentiates the efficiency of iNO.

CASE REPORTS

We used dypiridamole (Persantine), a specific PDE-V inhibitor, in two patients with CDH. Prenatal diagnosis showed a left-sided CDH at 23 weeks of gestation (GA) with intrathoracic stomach and left heart underdevelopment in the one infant and a right-sided CDH at 26 weeks GA with intrathoracic liver in the other. After antenatal corticoids, planned delivery was performed by the vaginal route at 38 weeks GA. Preoperative stabilization was achieved by high frequency oscillation, iNO and inotropic support over 24 h. Both had early pneumothorax drained by a chest tube. Despite optimization of ventilatory and hemodynamic support with surfactant replacement, iNO and adrenaline, oxygenation worsened progressively. Dypiridamole was introduced intravenously at 27 and 40 h, respectively, and improved oxygenation over the next 12 h. However, oxygenation again deteriorated and both patients died.

CONCLUSION

Dypiridamole enhanced the response to iNO in PPHN associated with CDH, although this effect was transient. Combined therapy of iNO with PDE-V inhibitors may improve pulmonary vasodilation in some forms of PPHN which do not respond to iNO, thereby reducing the need for extracorporeal membrane oxygenation (ECMO) and improving outcome.

Introduction of a proximal Stat5 site in the murine alpha-lactalbumin promoter induces prolactin dependency in vitro and improves expression frequency in vivo

In order to establish a possible correlation between in vitro prolactin induction and the transcriptional activity of mammary gene promoters in transgenic mice, a functional Stat5-binding site was created by means of site-directed mutagenesis at position -70 on a 560 bp murine alpha-lactalbumin promotor linked to a CAT reporter gene. Surprisingly, the wild-type promoter was constitutively active in vitro and could not be induced by prolactin. Introducing the proximal Stat5 site abolished this constitutive activity and resulted in prolactin dependence in both CHO-K1- and HC11-transfected cells. In transgenic mice, both the frequency of lines expressing the transgene and the prevalence of mid to late pregnancy expression were increased.

[Congenital diaphragmatic hernia. II. Is pulmonary hypoplasia an indefinable obstacle?]

Despite major insights into the pathogenesis and pathophysiology of congenital diaphragmatic hernia, and despite the availability of an antenatal diagnosis and continuous progress in neonatal intensive care, little improvement has been obtained in the prognosis of this malformation. Thus obstetricians, neonatologists and pediatric surgeons are still facing a several dilemma: dilemma before birth to predict the prognosis, i.e., to evaluate the severity of the associated pulmonary hypoplasia in order to decide whether or not to interrupt pregnancy; dilemma after birth in case of severe respiratory failure to decide how far to go in life support. Based on a review of the literature and their own experience, the authors attempt to recapitulate the perinatal management and outcome of this severe malformation.

Congenital diaphragmatic hernia. A cause of persistent pulmonary hypertension of the newborn which lacks an effective therapy

Congenital diaphragmatic hernia (CDH) is still an unsolved problem. A disease which was, for a long time, thought to be merely a hole in the diaphragm appears today to be an intriguing malformation with a poorly understood pathogenesis and a complex pathophysiology. CDH results in various degrees of pulmonary hypoplasia and severe persistent pulmonary hypertension of the newborn. Despite antenatal ultrasound diagnosis and continuous improvement in neonatal intensive care, these features could not be overcome, and the overall mortality rate in CDH is still reaching 50%. Experimental works during the past 20 years suggest that CDH is a disease of impaired lung development associated with, but not caused by, a structural defect of the diaphragm. Furthermore, there is increasing evidence that the lung in CDH is not only small but that there are numerous disorders (e.g. surfactant deficiency, decreased anti-oxidant activity, increased vascular reactivity with decreased nitric oxide and increased endothelin 1 activity, and left heart hypoplasia) which may be associated with impaired lung development. Although antenatal diagnosis of CDH is feasible by ultrasound, there is no reliable predictor of pulmonary hypoplasia, the main prognostic factor in CDH. Whilst modern therapeutic strategies such as high-frequency oscillatory ventilation, exogenous surfactant or inhaled nitric oxide may be beneficial in selected subjects, most newborns with hypoplastic lungs will not survive despite these postnatal therapies. Perhaps these newborns would benefit from antenatal treatment directed at altering lung growth early in utero to minimize pulmonary hypoplasia. Therefore, research is needed to elucidate the aetiology and pathogenesis of CDH. Knowledge about the cellular control of proliferation, differentiation and programmed cell death (apoptosis) in the organogenesis should clarify our understanding of these processes and allow us to develop drugs that stimulate lung growth or even correct the anatomical defect. Furthermore, early and reliable assessment of prognosis for fetuses with CDH at risk of death will become increasingly important in the identification of fetuses most likely to benefit from antenatal therapies and may eventually lead to decreased mortality.

Nitric oxide deficiency in fenfluramine- and dexfenfluramine-induced pulmonary hypertension

Dexfenfluramine and fenfluramine greatly increase the risk of developing pulmonary hypertension (PHT). The mechanism of anorexigen-associated PHT (AA-PHT) and the reason PHT occurs in a minority of people exposed are unknown. Anorexigens are weak pulmonary vasoconstrictors, but they become potent when synthesis of the endogenous vasodilator nitric oxide (NO) is suppressed. We hypothesized NO deficiency predisposes affected individuals to develop AA-PHT. A prospective, case-control, study was performed on consecutive patients with AA-PHT (n = 9). Two sex-matched control groups were selected: patients with primary PHT (P-PHT, n = 8) and normal volunteers (n = 12). Lung NO production (VNO) and systemic plasma oxidation products of NO (NOx) were measured at rest and during exercise. AA-PHT developed 17 +/- 6 mo after a short course of anorexigen (6 +/- 2 mo) and was irreversible. VNO was lower in AA-PHT than in P-PHT and correlated inversely with PVR (p < 0.05). The apparent VNO deficiency may have resulted from increased oxidative inactivation of NO in patients with AA-PHT, as their NOx levels were elevated (p < 0.05) in inverse proportion to VNO (r2 = 0. 55; p < 0.02). In susceptible persons, anorexigens can cause an irreversible syndrome of PHT, hypoxemia, and systemic vascular complications after brief exposures. These patients have a relative NO deficiency years after discontinuing the anorexigen, perhaps explaining their original susceptibility.

Disease-related response to inhaled nitric oxide in newborns with severe hypoxaemic respiratory failure. French Paediatric Study Group of Inhaled NO

Inhaled nitric oxide (iNO) has been shown to improve oxygenation in severe persistent pulmonary hypertension of the newborn (PPHN). However, PPHN is often associated with various lung diseases. Thus, response to iNO may depend upon the aetiology of neonatal acute respiratory failure. A total of 150 (29 preterm and 121 term) newborns with PPHN were prospectively enrolled on the basis of oxygenation index (OI) higher than 30 and 40, respectively. NO dosage was stepwise increased (10-80 ppm) during conventional mechanical or high-frequency oscillatory ventilation while monitoring the oxygenation. Effective dosages ranged from 5 to 20 ppm in the responders, whereas iNO levels were unsuccessfully increased up to 80 ppm in the nonresponders. Within 30 min of iNO therapy, OI was significantly reduced in either preterm neonates (51+/-21 vs 23+/-17, P < .0001) or term infants with idiopathic or acute respiratory distress syndrome (45+/-20 vs 20+/-17, P < .0001), 'idiopathic' PPHN (39+/-14 vs 14+/-9, P < .0001), and sepsis (55+/-25 vs 26+/-20, P < .0001) provided there was no associated refractory shock. Improvement in oxygenation was less significant and sustained (OI=41+/-16 vs 28+/-18, P < .001) in term neonates with meconium aspiration syndrome and much less (OI=58+/-25 vs 46+/-32, P < .01) in those with congenital diaphragmatic hernia. Only 21 of the 129 term newborns (16%) required extracorporeal membrane oxygenation (57% survival). Survival was significantly associated with the magnitude in the reduction in OI at 30 min of iNO therapy, a gestational age > or =34 weeks, and associated diagnosis other than congenital diaphragmatic hernia. Conclusion, iNO improves the oxygenation in most newborns with severe hypoxaemic respiratory failure including preterm neonates. However, response to iNO is disease-specific. Furthermore, iNO when combined with adequate alveolar recruitment and limited barotrauma using exogenous surfactant and HFOV may obviate the need for extracorporeal membrane oxygenation in many term infants.

[Congenital diaphragmatic hernia. I. Simple defect of the diaphragm or anomaly of the pulmonary mesenchyme?]

Described for the first time in 1848 by Bochdalek, congenital diaphragmatic hernia is still a hot topic. How can it be that a simple defect of the diaphragm still has a mortality rate reaching 50% in 1997, and this despite continuous progress in neonatal intensive care? If some problems remain unsolved, experimental studies over the past 30 years have raised some questions concerning the pathogenesis, and have shed some light into the pathophysiology of congenital diaphragmatic hernia. This article reviews the recent knowledge about the aetiology, pathogenesis and pathophysiology of this complex malformation.

Modification and repression of genes expressed in the mammary gland using gene targeting and other technologies

Transgenic experiments using oocyte micro-injection methodology are often performed in order to target expression of a foreign gene in a specific tissue or, to a lesser extent, to study the regulation of gene expression. However, the isolation of embryonic stem cells in mice and the development of antisense and ribozyme technologies have allowed more subtle alterations of endogenous gene expression to be achieved. The mammary gland is one of the few organs able to undergo several cycles of development, differentiation and apoptosis through complex multihormonal regulation during adult life. It is thus an attractive model to assess the in vivo function of some genes potentially involved in these mechanisms, either by silencing them or by partially repressing their expression. Furthermore, such alterations of gene expression have also been performed for more applied objectives such as the modification of milk composition for nutritional and technological purposes. This review will describe the experimental procedures used toward these aims and the results already obtained in this field. Some potential new targets will be suggested.

Molecular identification of the role of voltage-gated K+ channels, Kv1.5 and Kv2.1, in hypoxic pulmonary vasoconstriction and control of resting membrane potential in rat pulmonary artery myocytes

Hypoxia initiates pulmonary vasoconstriction (HPV) by inhibiting one or more voltage-gated potassium channels (Kv) in the pulmonary artery smooth muscle cells (PASMCs) of resistance arteries. The resulting membrane depolarization increases opening of voltage-gated calcium channels, raising cytosolic Ca2+ and initiating HPV. There are presently nine families of Kv channels known and pharmacological inhibitors lack the specificity to distinguish those involved in control of resting membrane potential (Em) or HPV. However, the Kv channels involved in Em and HPV have characteristic electrophysiological and pharmacological properties which suggest their molecular identity. They are slowly inactivating, delayed rectifier currents, inhibited by 4-aminopyridine (4-AP) but insensitive to charybdotoxin. Candidate Kv channels with these traits (Kv1.5 and Kv2.1) were studied. Antibodies were used to immunolocalize and functionally characterize the contribution of Kv1. 5 and Kv2.1 to PASMC electrophysiology and vascular tone. Immunoblotting confirmed the presence of Kv1.1, 1.2, 1.3, 1.5, 1.6, and 2.1, but not Kv1.4, in PASMCs. Intracellular administration of anti-Kv2.1 inhibited whole cell K+ current (IK) and depolarized Em. Anti-Kv2.1 also elevated resting tension and diminished 4-AP-induced vasoconstriction in membrane-permeabilized pulmonary artery rings. Anti-Kv1.5 inhibited IK and selectively reduced the rise in [Ca2+]i and constriction caused by hypoxia and 4-AP. However, anti-Kv1.5 neither caused depolarization nor elevated basal pulmonary artery tone. This study demonstrates that antibodies can be used to dissect the whole cell K+ currents in mammalian cells. We conclude that Kv2. 1 is an important determinant of resting Em in PASMCs from resistance arteries. Both Kv2.1 and Kv1.5 contribute to the initiation of HPV.

[Inhaled nitric oxide: a physiologic treatment of persistent pulmonary arterial hypertension in the newborn]

Fetal pulmonary circulation is characterized by high resistance and low pulmonary blood flow. Right-to-left shunting through the foramen ovale and/or patent ductus arteriosus is necessary to perfuse the placenta and insure fetal life. At birth, pulmonary arterial blood flow increases immediately by 8- to 10-fold, and allows pulmonary gas exchange and postnatal life. In some circumstances, this adaptation to extra-uterine life is inadequate, because of persistent high pulmonary resistance (PPHN). Due to the lack of a selective pulmonary vasodilator, the treatment of this syndrome remained purely symptomatic using high oxygen levels and barotraumatic mechanical hyperventilation. When this medical treatment failed, the only alternative was extracorporeal membrane oxygenation (ECMO). The discovery of the major role of various endothelium-derived factors including nitric oxide (NO) in the control of vascular reactivity led to dramatic switches in the concepts of severe neonatal respiratory failure and the therapeutic approach of PPHN. It was shown, first in experimental animals then in a few infants with hypoxemic respiratory failure, that NO inhalation selectively vasodilated the vasoconstricted pulmonary vessels, and reversed right-to-left shunting and refractory hypoxemia. Whether inhaled NO also reduces mortality and/or morbidity in hypoxic infants remains to be proven by appropriate randomized clinical trials. However, not only PPHN is associated with pulmonary diseases of various etiologies and underlying pathophysiologic mechanisms, but also inhaled NO is used in conjunction with other validated therapeutic strategies including ante- or postnatal steroids, exogenous surfactants, and high-frequency oscillatory ventilation. Thus, the relevant primary endpoint might be not only crude survival but the most physiological and economical way of obtaining it.

Acute respiratory distress syndrome in children

The adult (acute) respiratory distress syndrome is a significant cause of morbidity in children. The mortality rates remain elevated, greater than 50%, and even greater than 80% in patients with underlying malignancies. The therapeutic interventions remain mainly supportive. Strategies of conventional mechanical ventilation are directed toward the use of high positive end-expiratory pressures, low positive inspiratory pressure, and permissive hypercapnia. High-frequency oscillatory ventilation and tracheal insufflation are not yet used extensively, although they should contribute to less aggressive ventilation. Surfactant replacement, nitric oxide inhalation, and partial liquid ventilation seem to be promising technologies, but controlled clinical studies are necessary before their wide-spread use. Extracorporeal membrane oxygenation remains the alternative technology in case of failure of conventional support.

[Roles of vasoactive factors synthetized by endothelium in pulmonary arterial hypertension]

Pulmonary vascular endothelium synthesizes and releases two groups of vasoactive substances, namely the endothelium-derived relaxing and contracting factors. Among the former, the effects of nitric oxide (NO), formerly known as endothelium-derived relaxing factor (EDRF), and those of the so-called endothelium-derived hyperpolarizing factor (EDHF) have been extensively investigated. Among the latter, endothelin is probably one of the most potent endogenous vasoconstrictors. NO is a free radical which can be readly inactivated by hemoglobin. NO has all the characteristics of a gas, whereas its pharmacological properties are consistent with those of an endogenous nitrovasodilator. Therefore, inhalation of the gas NO is now considered as one of the most promising means to treat persistent pulmonary hypertension of the newborn. EDHF relaxes vascular smooth muscle through activation of ATP-dependent potassium channels. Both the chemical nature and the physiological role of EDHF are still unclear. The pharmacological properties of endothelin are far from being unequivocal. It is a potent vasoconstrictor, when it directly acts on vascular smooth muscle. However, it can also induce the release of NO and EDHF, hence causing vasorelaxation. These effects of endothelin are mediated by various transduction pathways. Activations of ET-B receptors located on endothelium on the one hand, and ET-A receptors located on smooth muscle on the other hand, are responsible for relaxation and constriction of vascular smooth muscle, respectively. Such highly complex cellular mechanisms highlight the need for further insight into the physiology of the cell related to the pulmonary circulation. This, in turn, will help to better define the target upon which one can try to correct the abnormal function of the cell underlying the pathophysiological processes.

Expression of a bovine alpha-lactalbumin transgene in alpha-lactalbumin-deficient mice can rescue lactation. In vivo relationship between bovine alpha-lactalbumin expression content and milk composition

Lowering the lactose content of milk in vivo has two potential benefits: to develop milk products for lactose intolerant people (Delmont, 1983) and to produce a more concentrated milk, reducing milk storage volume and milking frequency without affecting the overall fat and protein yields. Lactose synthesis in the lactating mammary gland results from the interaction of α-lactalbumin (α-la) with a Golgian UDP-galactosyltransferase (EC 2.4.1.22), and it has been suggested that lactose and α-la contents are directly related (Fitzgerald et al. 1970). Evidence that α-la is the only protein responsible for the in vivo induction of lactose synthesis came recently from knock-out experiments of the relevant gene (Stinnakre et al. 1994; Stacey et al. 1995), which disrupt lactation, as lactose-deprived milk of α-la-deficient mice is highly viscous. However, although the lactose, fat and protein contents of the milk were found to be directly related to the quantity of α-la present (Stinnakre et al. 1994), only in mice homozygous for the α-la null allele was there a significant alteration of milk concentration (Stacey et al. 1995). Stacey et al. (1995) also demonstrated that human α-la could substitute for its mouse counterpart via homologous recombination.

In the present study, we report the generation of transgenic mice producing only bovine α-la by back-crossing animals from four independent bovine α-la transgenic lines with α-la-deficient mice. Our work confirms that foreign α-la can substitute for the mouse protein and suggests a negative correlation between the α-la content and protein and fat concentrations in milk.

Developmental regulation of murine integrin beta 1 subunit- and Hsc73-encoding genes in mammary gland: sequence of a new mouse Hsc73 cDNA

A partial integrin beta 1 subunit-encoding cDNA (Itg beta 1) and a new heat-shock protein 70-like-encoding cDNA (Hsc73) homologous to rat Hsc73 were cloned by differential display and RT-PCR from mouse mammary gland. Their developmental regulation during pregnancy, lactation and involution is reported. The Itg beta 1 mRNA content was stable in the first half of gestation, decreased to a minimum during lactation and increased markedly in early involution. Hsc73 gene expression was high in the first half of gestation and decreased to a minimum during lactation. The possible significance of the two observed patterns of expression is discussed.

Efficient and specific ribozyme-mediated reduction of bovine alpha-lactalbumin expression in double transgenic mice

Transgenic mice carrying a bovine alpha-lactalbumin (alpha-lac) specific ribozyme gene under the transcriptional control of the mouse mammary tumor virus long terminal repeat were generated and cross-bred with animals that highly express a bovine alpha-lac transgene (0.4 mg of alpha-lac/ml(-1) of milk). The ribozyme contains the hammerhead catalytic domain, flanked by 12-nt sequences complementary to the 3' untranslated region of bovine alpha-lac transcript. High-level expression of the ribozyme gene was detected by Northern blot analysis in the mammary gland of 7-8 day lactating transgenic mice, from 3 of 12 lines analyzed. Heterozygous expression of the ribozyme resulted in a reduction in the levels of the target mRNA to 78, 58, and 50% of that observed in the nonribozyme transgenic littermate controls for three independent lines. The ribozyme-mediated reduction in the levels of the bovine protein paralleled that observed for the mRNA, and was positively correlated with the level of expression of the ribozyme. In nonribozyme expressing transgenic mice, the level of bovine alpha-lac mRNA and protein was not affected. The specificity of this activity is demonstrated by the absence of a reduction in the levels of the endogenous murine alpha-lac mRNA or protein. These results demonstrate the feasibility of ribozyme-mediated down-regulation of highly-expressed transcripts in transgenic animals.

Identification and mapping on chromosome 9 of RAPD markers linked to Sw-5 in tomato by bulked segregant analysis

Bulked segregant analysis was used to identify random amplified polymorphic DNA (RAPD) markers linked to the Sw-5 gene for resistance to tomato spotted wilt virus (TSWV) in tomato. Using two pools of phenotyped individuals from one segregating population, we identified four RAPD markers linked to the gene of interest. Two of these appeared tightly linked to Sw-5, whereas another, linked in repulsion phase, enabled the identification of heterozygous and susceptible plants. After linkage analysis of an F2 population, the RAPD markers were shown to be linked to Sw-5 within a distance of 10.5 cM. One of the RAPD markers close to Sw-5 was used to develop a SCAR (sequence characterized amplified region) marker. Another RAPD marker was stabilized into a pseudo-SCAR marker by enhancing the specificity of its primer sequence without cloning and sequencing. RAPD markers were mapped to chromosome 9 on the RFLP tomato map developed by Tanksley et al. (1992). The analysis of 13 F3 families and eight BC2 populations segregating for resistance to TSWV confirmed the linkage of the RAPD markers found. These markers are presently being used in marker-assisted plant breeding.

Hemodynamics and oxygenation changes induced by the discontinuation of low-dose inhalational nitric oxide in newborn infants

OBJECTIVE

To assess changes associated with nitric oxide (NO) discontinuation in neonates receiving inhalational NO therapy as a treatment for pulmonary hypertension of the neonate (PPHN).

DESIGN

Prospective study.

SETTING

A pediatric PICU in a university hospital.

PATIENTS AND METHODS

Ten neonates were included. NO discontinuation was attempted when the oxygenation index fell below 10. The mean NO concentration was 4.9 +/- 0.8 ppm. Each infant was studied over three successive 5-min periods and was assigned to either group 1 (NO1+, NO2+, NO-) or group 2 (NO1+, NO-, NO2+).

MEASUREMENTS AND RESULTS

Postductal transcutaneous PO2 (tcPO2), postductal oxygen saturation with pulse oxymetry (SpO2), systolic and diastolic blood pressure (BP), heart rate (HR), left ventricular shortening fraction (LVSF), cardiac output (CO), and ratio of pulmonary artery time to peak velocity and right ventricular ejection time (TPV/RVET) were similar during the two successive NO+ periods (group 1), thus demonstrating that the measurements were reproducible. NO removal (groups 1 and 2) did not modify systolic or diastolic BP, HR, CO, or LVSF but did induce a significant decline in SpO2, tcPO2 (- 25 +/- 5%) and TPV/RVET ratio (- 25 +/- 3%). No reinstitution reversed the effects of NO withdrawal on tcPO2, SpO2 and TPV/RVET ratio (group 2) without any changes in systemic hemodynamics.

CONCLUSION

The shut-off of low-dose NO induced in each patient a decrease in oxygen delivery that may be due to increased pulmonary vascular resistances and/or redistribution of pulmonary blood flow with ventilation-perfusion mismatching. The optimum weaning-off procedure of inhalational NO remains to be determined.

Thrombosis of the arterial cannula during extracorporeal membrane oxygenation in a full-term newborn infant

The authors report a rare case of cannula thrombosis during extracorporeal membrane oxygenation (ECMO). A full-term newborn infant was successively placed on single-cannula veno-venous extracorporeal lung support and then on veno-arterial ECMO, because of persistent pulmonary hypertension. At 140 hours of ECMO, the infant displayed general cyanosis except in the right arm. Since asymmetric hypoxemia during ECMO may be related either to cannula malposition or to a tip thrombosis, a chest x-ray after contrast injection into the arterial line of the circuit was performed. It showed an opacification of the whole cannula but for the last distal centimeter, and of the vascular bed extending from the right subclavian artery. Cannula thrombosis was suspected and confirmed by removal of the arterial cannula. Demonstration of cannula thrombosis by opacification of the arterial line of the circuit indicates catheter removal.

High-level, stage- and mammary-tissue-specific expression of a caprine kappa-casein-encoding minigene driven by a beta-casein promoter in transgenic mice

A 5' truncated caprine (ca) kappa-casein-encoding gene (kappa Cas) was fused to the 3' end of a 3' truncated ca beta Cas. The kappa Cas form comprised the 0.8-kb 3' end of intron 2, the remaining part of the transcription unit containing codons -2 to stop 172, and 0.43 kb of the 3' flanking region. The beta Cas form comprised a 3-kb 5' flanking region and the 5' end of the transcription unit terminating 69 bp downstream from exon 2 which encodes the 15-amino-acid (aa) signal peptide and the first 2 aa of mature beta Cas. The resulting hybrid gene driven by the beta Cas promoter was expressed in all eight lines of transgenic mice investigated, although at different levels. In two lines, the yield of recombinant (re-) kappa Cas was > or = 3 mg/ml of milk. The stage- and mammary tissue-specific expression was similar to that of endogenous beta Cas. The re-kappa Cas differed from its goat milk counterpart by the occurrence of four extra aa at the N-terminal end, indicating that the signal peptidase released the beta Cas signal peptide. According to sedimentation analyses of murine milk containing > or = 3 mg re-kappa Cas/ml, the latter essentially occurred in micelles. Preliminary comparative assays of the behavior of ca alpha s1Cas-kappa Cas and alpha s1Cas-re-kappa Cas mixtures upon incremental addition of Ca2+ showed that re-kappa Cas had the capacity to protect alpha s1Cas against Ca(2+)-induced precipitation in forming stable micelles.(ABSTRACT TRUNCATED AT 250 WORDS)

Complete sequence of the ovine beta-casein-encoding gene and interspecies comparison

The 9149-bp transcription unit encoding ovine beta-casein (Cas) and 4636 bp of 5' flanking region were completely sequenced. The gene is composed of nine exons and its overall organization is similar to that of its counterparts from other species. Intron 4, the largest, shares three similar stretches (sizes ranging from 0.1 to 0.3 kb) with the region upstream from the transcription unit. These common sequences are part of short interspersed nuclear elements (SINE) specific to Bovidae (Bov). Intron 4 contains two 274-bp Bov-A2 SINE in opposite orientation, as well as a full-length 569-bp Bov-B SINE. This latter SINE, also present in caprine intron 4, is missing in cattle. This suggests that the amplification of Bov-SINE has continued after the divergence of cattle from sheep and goats, assuming that the presently known sequences are representative of these species.

Is there a role for inhaled nitric oxide in pediatric ARDS?

Despite advances in ventilator management and use of extracorporeal lung support, mortality related to ARDS in pediatric patients has not been reduced over the past 20 years. Progressive respiratory failure, due to evolution of the primary illness or to complications of ventilator therapy, significantly contributes to poor outcome. ARDS is characterized by severe ventilation-perfusion mismatch and by pulmonary hypertension. Because of their side effects which affect systemic hemodynamic status or worsen intrapulmonary shunting, intravenous vasodilator trials have been of limited interest. Nitric oxide (NO) has been recognized as a gas with vasodilator properties. In neonates studies have shown that inhaled NO may have an important role in the therapy of persistent pulmonary hypertension. Inhaled NO in adults with severe ARDS has been shown to reduce pulmonary hypertension without producing systemic vasodilation. This reduction of pulmonary vascular resistances may reduce pulmonary edema formation, decrease vasoconstrictor response to cardiotonic agents, and improve biventricular function. In addition, arterial oxygenation seems to be increased by improved matching of ventilation with perfusion. Improvement of oxygenation with inhaled NO suggests that use of lower tidal volumes and FIO2 may be more successful. Until now, there are no published studies regarding NO administration in ARDS affecting nonneonatal pediatric patients. However, the results obtained in adults and newborns suggest that inhaled NO may be a useful adjuvant therapy of ARDS in children, possibly in association with other therapies. Even in adults it remains unclear whether therapy with inhaled NO can reduce morbidity and mortality. Prospectives and randomized studies are essential to assess the real utility of inhaled NO in ARDS.(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiographic investigation of inhaled nitric oxide in newborn babies with severe hypoxaemia

Nitric oxide inhalation can benefit newborn babies with right-to-left extrapulmonary shunt (EPS). Using doppler ultrasound, we compared the effects of nitric oxide on systemic oxygenation and mean pulmonary-blood-flow velocity (MPBFV) in severely hypoxic babies with or without EPS. With a median (interquartile range) dose of 20 (32) parts per million, oxygenation index decreased significantly in both groups (EPS, 49 [19] vs 11 [9]; non-EPS, 40 [11] vs 20 [13]). The decrease was significantly greater in the EPS group. MPBFV increased significantly in the EPS group (18 [4] vs 29 [8] m/s) only. Nitric oxide may improve systemic oxygenation in neonates with severe hypoxaemia secondary to EPS by increasing pulmonary blood flow, and in those without EPS by improving ventilation-perfusion matching.

Creation and phenotypic analysis of alpha-lactalbumin-deficient mice

alpha-Lactalbumin is an abundant milk-specific calcium metalloprotein which has an evolutionary relationship to lysozyme. It modifies the substrate specificity of a Golgi galactosyltransferase by forming the lactose synthetase binary complex. Lactose, together with other sugars and diffusible ions, is responsible for the osmotic pressure of milk. To assess the involvement of alpha-lactalbumin in lactogenesis, alpha-lactalbumin-deficient mice were created by disrupting the gene by homologous recombination in embryonic stem cells. Homozygous mutant mice are viable and fertile but females cannot feed their offspring. They produce a highly viscous milk that pups appear to be unable to remove from the mammary gland. This milk is rich in fat and protein and is devoid of alpha-lactalbumin and lactose. The phenotype of heterozygous mice was found to be intermediate, with a 40% decrease in alpha-lactalbumin but only a 10-20% decrease in the lactose content of their milk compared with wild-type animals. These results emphasize the key function of alpha-lactalbumin in lactogenesis and open new opportunities to manipulate milk composition.

Doppler echocardiographic assessment of pulmonary circulation in severe respiratory failure of the neonate: an aid for extracorporeal lung support indications

Extracorporeal lung support (ECLS) for newborns with acute respiratory failure has achieved increased popularity over the last decade. However, precise criteria for its implementation remain controversial. The aim of this study was to assess the value of Doppler echocardiography (DE) in 31 neonates with PaO2 of < or = 50 mmHg, FIO2 of 1, and optimal ventilation. Treatment included mechanical ventilation, paralysis, volume loading, vasopressors, and tolazoline. Markers indicative of ECLS (failure of maximal medical therapy, assessed by AaDO2 of more than 610 mm Hg beyond 8 hours and/or an oxygenation index (OI = mean airway pressure x FIO2%/postductal PaO2) of more than 40 beyond 4 to 6 hours) were present in 23 (group 1) and absent in eight (group 2). Shunt direction and systolic pulmonary arterial pressure (sPAP) calculated from tricuspid insufficiency velocity were assessed using DE. At the time of admission, sPAP was significantly higher in group 1 (62.1 v 43.7 mm Hg). On day 1, group 1 differed from group 2 in maximum sPAP value (73.2 v 44.4 mm Hg), PaCO2 (56.1 v 40 mm Hg), right-to-left shunting (85% v 25% of the patients), and pulmonary-to-systemic-pressure systolic ratio (sPAP:sSAP) (1.29 v 0.75). Patients with an sPAP:sSAP ratio of more than 1 and patients with high sPAP associated with high PaCO2 on day 1, all later (average, 10 hours later) fulfilled ECLS criteria; this suggests that DE assessment of pulmonary circulation may yield early and predictive markers of impending ECLS indication. Further confirmation of these results would help avoid unnecessary delays in ECLS implementation in newborns with severe respiratory failure.

Structure and function of milk protein genes

Interspecies comparisons of cDNA and mosaic milk protein genes have confirmed their high rate of evolution, but the overall gene organization has been conserved. The three Ca-sensitive casein genes, which share common motifs in the promoter region and contain similar sequences that encode signal peptide and multiple phosphorylation sites, probably derived from a common ancestor. alpha s1- and alpha s2-casein genes, divided into many small exons, undergo complex splicing, and the deleted caseins arise from exon skipping. The four bovine casein genes are clustered on 200 kb of chromosome 6. alpha-Lactalbumin and beta-lactoglobulin pseudogenes occur in ruminants. Study of the expression of native and modified milk protein genes in mammary cell lines and transgenic animals and DNA footprinting have shown the occurrence of important regulatory motifs in the proximal 5' flanking region, including one recognized by a specific mammary nuclear factor. Good stage- and tissue-specific expression has been obtained in transgenic animals with milk protein genes having less than a 3-kb 5' flanking region. Better knowledge of both the structure and function of milk protein genes, which has already allowed the use of powerful techniques for the rapid identification of alleles, offers the potential for the genetic modification of milk composition.