Adaptations to infer fitness interdependence promote the evolution of cooperation

The evolution of cooperation is a major question in the biological and behavioral sciences. While most theoretical studies model cooperation in the context of an isolated interaction (e.g., a Prisoner's Dilemma), humans live in heterogeneous social environments, characterized by large variations in fitness interdependence-the extent to which one's fitness is affected by others. Theoretical and experimental work indicates that humans can infer, and respond to, variations in interdependence. In a heterogeneous ancestral environment, these psychological mechanisms to infer fitness interdependence could have provided a selective advantage, allowing individuals to maximize their fitness by deciding when and with whom to cooperate. Yet, to date, the link between cognitive inference, variation in fitness interdependence, and cooperation remains unclear. Here we introduce a theoretical framework to study the evolution of inference and cooperation in heterogeneous social environments, where individuals experience interactions with varying levels of corresponding interests. Using a combination of evolutionary game theory and agent-based modeling, we model the evolution of adaptive agents, who incur a cost to infer interdependence, in populations of fixed-behavior agents who always cooperate or defect. Our results indicate that natural selection could promote the evolution of psychological mechanisms to infer fitness interdependence, provided that there is enough variation in fitness interdependence to offset the cost of inference. Under certain conditions, the fixation of adaptive agents results in higher levels of cooperation. This depends crucially on the type of inference performed and the features of the interdependence landscape.

The limits of metabolic heredity in protocells

The universal core of metabolism could have emerged from thermodynamically favoured prebiotic pathways at the origin of life. Starting with H 2 and CO 2 , the synthesis of amino acids and mixed fatty acids, which self-assemble into protocells, is favoured under warm anoxic conditions. Here, we address whether it is possible for protocells to evolve greater metabolic complexity, through positive feedbacks involving nucleotide catalysis. Using mathematical simulations to model metabolic heredity in protocells, based on branch points in protometabolic flux, we show that nucleotide catalysis can indeed promote protocell growth. This outcome only occurs when nucleotides directly catalyse CO 2 fixation. Strong nucleotide catalysis of other pathways (e.g. fatty acids and amino acids) generally unbalances metabolism and slows down protocell growth, and when there is competition between catalytic functions cell growth collapses. Autocatalysis of nucleotide synthesis can promote growth but only if nucleotides also catalyse CO 2 fixation; autocatalysis alone leads to the accumulation of nucleotides at the expense of CO 2 fixation and protocell growth rate. Our findings offer a new framework for the emergence of greater metabolic complexity, in which nucleotides catalyse broad-spectrum processes such as CO 2 fixation, hydrogenation and phosphorylation important to the emergence of genetic heredity at the origin of life.

The need for high-quality oocyte mitochondria at extreme ploidy dictates mammalian germline development

Selection against deleterious mitochondrial mutations is facilitated by germline processes, lowering the risk of genetic diseases. How selection works is disputed: experimental data are conflicting and previous modeling work has not clarified the issues; here, we develop computational and evolutionary models that compare the outcome of selection at the level of individuals, cells and mitochondria. Using realistic de novo mutation rates and germline development parameters from mouse and humans, the evolutionary model predicts the observed prevalence of mitochondrial mutations and diseases in human populations. We show the importance of organelle-level selection, seen in the selective pooling of mitochondria into the Balbiani body, in achieving high-quality mitochondria at extreme ploidy in mature oocytes. Alternative mechanisms debated in the literature, bottlenecks and follicular atresia, are unlikely to account for the clinical data, because neither process effectively eliminates mitochondrial mutations under realistic conditions. Our findings explain the major features of female germline architecture, notably the longstanding paradox of over-proliferation of primordial germ cells followed by massive loss. The near-universality of these processes across animal taxa makes sense in light of the need to maintain mitochondrial quality at extreme ploidy in mature oocytes, in the absence of sex and recombination.

Analysis of Eurasian Stone curlew (Burhinus oedicnemus) microbial flora reveals the presence of multi-drug resistant pathogens in agro-pastoral areas of Sicily (Italy)

Spread of multi-drug resistant (MDR) bacteria in natural environments pose a risk to human and animal health. Wild birds are considered to be reservoirs of human pathogens and vectors of antimicrobial resistance distribution in the environment. The aim of this study is to assess the occurrence of antibiotic resistant bacteria in isolates from bird specimens living in three agro-pastoral areas of the southeastern Sicily. We analyzed the microbiomes of the Eurasian Stone curlew Burhinus oedicnemus (Charadriiformes, Aves) and identified 91 Gram positive and 212 Gram negative strains, whose antimicrobial susceptibility to 11 and 9 antibiotic classes (respectively) was evaluated using agar disk diffusion test. Isolates showed significant levels of antimicrobial resistance, and a high percentage of MDR strains was found both between the Gram positive (49.4%) and the Gram negative (34.9%). Multi-drug resistance levels are higher among strains isolated in the beak and the eye than among enteric (faeces and cloaca) strains. Our results indicate high levels of MDR strains among wild bird populations, with a potential threat to wildlife and human populations.

Genome expansion in early eukaryotes drove the transition from lateral gene transfer to meiotic sex

Prokaryotes acquire genes from the environment via lateral gene transfer (LGT). Recombination of environmental DNA can prevent the accumulation of deleterious mutations, but LGT was abandoned by the first eukaryotes in favour of sexual reproduction. Here we develop a theoretical model of a haploid population undergoing LGT which includes two new parameters, genome size and recombination length, neglected by previous theoretical models. The greater complexity of eukaryotes is linked with larger genomes and we demonstrate that the benefit of LGT declines rapidly with genome size. The degeneration of larger genomes can only be resisted by increases in recombination length, to the same order as genome size - as occurs in meiosis. Our results can explain the strong selective pressure towards the evolution of sexual cell fusion and reciprocal recombination during early eukaryotic evolution - the origin of meiotic sex.

Positional effects on lung mechanics of ventilated preterm infants with acute and chronic lung disease

BACKGROUND

The role of prone position in preterm infants has not been completely clarified. We investigated prone versus supine posture-related changes in respiratory system resistance (Rrs) and reactance (Xrs) measured by the Forced Oscillation Technique (FOT) in mechanically ventilated preterm newborns.

METHODS

Patients were studied in the supine versus prone positions in random order. Oxygen saturation, transcutaneous partial pressure of oxygen (ptcO2 ), carbon dioxide (ptcCO2 ), Rrs and Xrs were measured in each position.

RESULTS

Nine patients with respiratory distress syndrome (RDS) and nine with evolving broncho-pulmonary dysplasia (BPD) were studied. Rrs was, on average, 9.8 (1.3, 18.3 as 95%CI) cmH2 O*s/l lower in the prone compared to the supine position (P = 0.02), while no differences in Xrs, ptcO2 , ptcCO2 , and breathing pattern were observed between postures. Only patients with evolving BPD showed a significant reduction of Rrs from 69.0 ± 27.4 to 53.0 ± 16.7 cmH2 O*s/l, P = 0.01. No significant correlations were found between changes in lung mechanics and ptcO2 , ptcCO2 , or breathing pattern.

CONCLUSIONS

On short-term basis, prone positioning does not offer significant advantages in lung mechanics in mechanically ventilated infants with RDS, while it is associated with lower Rrs values in patients with evolving BPD.

Comparison between two different modes of non-invasive ventilatory support in preterm newborn infants with respiratory distress syndrome mild to moderate: preliminary data

Despite of improved survival of premature infants, the incidence of long term pulmonary complications, mostly associated with ventilation-induced lung injury, remains high. Non invasive ventilation (NIV) is able to reduce the adverse effects of mechanical ventilation. Although nasal continuous positive airway pressure (NCPAP) is an effective mode of NIV, traumatic nasal complications and intolerance of the nasal interface are common. Recently high flow nasal cannula (HFNC) is emerging as a better tolerated form of NIV, allowing better access to the baby's face, which may improve nursing, feeding and bonding. HFNC may be effective in the treatment of some neonatal respiratory conditions while being more user-friendly for care-givers than conventional NCPAP. Limited evidence is available to support the specific role, efficacy and safety of HFNC in newborns and to demonstrate efficacy compared with NCPAP; some studies suggest a potential role for HFNC in respiratory care of the neonate as a distinct non invasive ventilatory support. We present the preliminary data of a randomized clinical trial; the aim of this study was to assess efficacy and safety of HFNC compared to NCPAP in preterm newborns with mild to moderate respiratory distress syndrome (RDS).

[Therapy with high-flow nasal prongs in preterm infants]

Despite of improved survival of premature infants, the incidence of long-term pulmonary complications, mostly associated with ventilation-induced lung injury, remains high. Non invasive ventilation (NIV) is able to reduce the adverse effects of mechanical ventilation. Although nasal continuous positive airway pressure (NCPAP) is an effective mode of NIV, traumatic nasal complications and intolerance of the nasal interface are common. Recently high flow nasal cannula (HFNC) is emerging as an efficient, better tolerated form of NIV, allowing better access to the baby's face, which may improve nursing, feeding and bonding. The aim of this review is to discuss the available evidence of effectiveness and safety of HFNC in preterm newborns with respiratory distress syndrome (RDS). It is known that distending pressure generated by HFNC increases with increasing flow rate and decreasing infant size and varies according to the amount of leaks by nose and mouth. The effects of HFNC on lung mechanics, its clinical efficacy and safety are still insufficiently investigated. In conclusion, there is a growing evidence of the feasibility of HFNC as an alternative mode of NIV. However, further larger randomized trials are required, before being able to recommend HFNC in the treatment of moderate respiratory distress of preterm infants.

High-flow nasal cannula: transient fashion or new method of non-invasive ventilatory assistance?

Respiratory failure in the premature infants remains a difficult challenge. An alternative to the use of nasal continuous positive airway pressure (NCPAP) as a non-invasive modality to support respiratory distress in premature infants has been the recent introduction of high flow nasal cannula (HFNC) devices in many neonatal units. There has been increased use of HFNC presumably because of anecdotal reports and experience that it is easy to use, and well tolerated by the infants, while experiencing decreased nasal septumerosion. The paucity of evidence regarding its efficacy and safety, would support a caution approach to the use of HFNC. Particular concern has focused on the imprecise regulation and generation of pressure that may occur at higher flows especially in the smallest of infants.

Relationship between respiratory impedance and positive end-expiratory pressure in mechanically ventilated neonates

PURPOSE

To evaluate the feasibility of forced oscillation technique (FOT) measurements at the bedside and to describe the relationship between positive end-expiration pressure (PEEP) and lung mechanics in different groups of ventilated infants.

METHODS

Twenty-eight infants were studied: 5 controls, 16 newborns with respiratory distress syndrome (RDS) and 7 chronically ventilated newborns that developed bronchopulmonary dysplasia. An incremental/decremental PEEP trial was performed by changing PEEP in 1-min steps of 1 cmH(2)O between 2 and 10 cmH(2)O. Forced oscillations at 5 Hz were superimposed on the ventilator waveform. Pressure and flow, measured at the inlet of the ETT, were used to compute resistance (Rrs) and reactance (Xrs).

RESULTS

In controls Rrs and Xrs were on average 41 ± 21 and -22 ± 6 cmH(2)O s/l respectively and were almost unaffected by PEEP. RDS infants presented similar Rrs (48 ± 25 cmH(2)O s/l) and reduced Xrs (-71 ± 19 cmH(2)O s/l) at the beginning of the trial. Two behaviours were observed as PEEP was increased: in extremely low birth weight infants Xrs decreased with PEEP with marked hysteresis; in very low and low birth weight infants Xrs and Rrs were less PEEP dependent. Chronically ventilated infants had very high Rrs and very negative Xrs values at very low PEEPs (121 ± 41 and -95 ± 13 cmH(2)O s/l at PEEP = 2 cmH(2)O) that markedly changed as PEEP exceeded 3-4 cmH(2)O.

CONCLUSIONS

Rrs and Xrs measurement in preterm newborns is feasible, and data are representative of the lung mechanics and very sensitive to its changes with PEEP, making FOT a promising technique for the non-invasive bedside titration of mechanical ventilation in preterm newborns.

Pregnancy and neonatal respiratory outcome

Preterm labor is the final common pathway of different complications of pregnancy and despite substantial progress in antenatal care, preterm birth remains a major health issue across the globe. Preterm deliveries in the larger group of spontaneous preterm labor or preterm prelabor rupture of membranes (PPROM) are often associated with intrauterine chorioamnionitis. Current evidence underlines the role of "inflammatory" and "placental dysfunction" disorders in pregnancy on prematurity-associated morbidity, particularly respiratory outcome. (www.actabiomedica.it).

Delayed meconium passage in very low birth weight infants

BACKGROUND

Delayed meconium passage, typical of premature newborns, is a predisposing condition for bowel perforation with a significant risk of morbidity and mortality.

AIM OF THE STUDY

A retrospective study was undertaken to verify the entity of the disease, assess the average time to meconium passage in a neonatal population of very low birth weight (VLBW) infants, and identify associated risk factors.

METHODS

The time of first stool passage was studied in 110 VLBW infants (weighing less than 1500 g at birth). Their perinatal features, clinical course, and treatment were reviewed and studied retrospectively.

RESULTS

Delayed meconium passage was recorded in 81% of this group. Patent ductus arteriosus, mechanical ventilation and uteroplacental insufficiency were significantly associated with delayed passage. An inverse relationship between gestational age, birth weight and meconium passage was found. Bowel perforation occurred in 4.5% of this neonatal population with a mortality of 50%.

CONCLUSIONS

In very low birth weight infants delay in the passage of the first stool is common. Perforation in these patients may represent a fatal event, and procedures such as daily rectal enemas, which can prevent this complication, must be applied.

[Delivery room intensive care unit]

Over the most recent 10 years there have been no significant further improvements in survival or morbidity rates of preterm infants, mostly the extremely-low-gestational-age-neonates (ELGANs, defined as less than or equal to 28 weeks' gestation).The incidence of some of the major morbidities associated with extreme prematurity, such as BPD, could potentially be affected by management in the first minutes of life; it may be necessary to apply the principles of care that occur in the neonatal intensive care unit in the delivery room to achieve a further improvements in short and long-term outcome of these neonates. Up to now, the care of the smallest preterm infants in the delivery room has received little attention: few resuscitation protocols addressed to these newborns, not advanced equipment used and subjective monitoring based on clinical examination. Therefore, it may be useful to incorporate an intensive care environment into the delivery room to enhance survival rates and reduce morbidity of the extremely preterm infants. New approaches in the first minutes of life using more gentle parameters of intervention are being studied but further evidence is needed to improve resuscitation procedures in these newborns.

Pharyngeal pressure value using two continuous positive airway pressure devices

The aim of the study was to measure the difference between the set continuous positive airway pressure (CPAP) value and the pharyngeal pressure reading during CPAP in premature infants with mild respiratory distress syndrome, using two different devices: hood CPAP and the conventional nasal system. The preliminary results suggest that hood CPAP may produce more stable pharyngeal pressure than the conventional nasal device.

Prenatal diagnosis and postnatal management of congenital laryngeal atresia in a preterm infant

Laryngeal atresia is a rare congenital cause of high airway obstruction that can lead to death if not correctly recognized and treated at birth. Postnatal management is difficult and the prognosis is often poor. We report a case of prenatal diagnosis of laryngeal atresia in a fetus that was delivered preterm at 29 weeks of gestation. Tracheotomy was performed as an ex utero intrapartum treatment (EXIT) to guarantee patent airway, and laryngotracheoplasty was performed at 22 months of corrected age. A favorable ventilatory and neurodevelopmental outcome was observed at 33 months of age.

Respiratory management of the premature infant in the delivery room

The preterm surfactant-deficient lung is highly susceptible to tissue injury with the initiation of ventilation. The respiratory management of preterm infants in the delivery room may be the key to minimizing acute lung injury and its sequelae, including chronic lung disease. Volume-targeted ventilation, optimization of the alveolar recruitment with positive end-expiratory pressure and prophylaxis with surfactant in infants with small volumes of lung gas and delicate lung tissue might help in limiting acute damage during resuscitation in the delivery room. It is desirable to monitor oxygen saturation and tailor oxygen supplementation when resuscitating premature infants.

Prophylactic nasal continuous positive airways pressure in newborns of 28-31 weeks gestation: multicentre randomised controlled clinical trial

BACKGROUND

The role of nasal continuous positive airways pressure (nCPAP) in the management of respiratory distress syndrome in preterm infants is not completely defined.

OBJECTIVE

To evaluate the benefits and risks of prophylactic nCPAP in infants of 28-31 weeks gestation.

DESIGN

Multicentre randomised controlled clinical trial.

SETTING

Seventeen Italian neonatal intensive care units.

PATIENTS

A total of 230 newborns of 28-31 weeks gestation, not intubated in the delivery room and without major malformations, were randomly assigned to prophylactic or rescue nCPAP.

INTERVENTIONS

Prophylactic nCPAP was started within 30 minutes of birth, irrespective of oxygen requirement and clinical status. Rescue nCPAP was started when Fio2 requirement was > 0.4, for more than 30 minutes, to maintain transcutaneous oxygen saturation between 93% and 96%. Exogenous surfactant was given when Fio2 requirement was > 0.4 in nCPAP in the presence of radiological signs of respiratory distress syndrome.

MAIN OUTCOME MEASURES

Primary end point: need for exogenous surfactant. Secondary end points: need for mechanical ventilation and incidence of air leaks.

RESULTS

Surfactant was needed by 22.6% in the prophylaxis group and 21.7% in the rescue group. Mechanical ventilation was required by 12.2% in both the prophylaxis and rescue group. The incidence of air leaks was 2.6% in both groups. More than 80% of both groups had received prenatal steroids.

CONCLUSIONS

In newborns of 28-31 weeks gestation, there is no greater benefit in giving prophylactic nCPAP than in starting nCPAP when the oxygen requirement increases to a Fio2 > 0.4.

Impact of targeted-volume ventilation on lung inflammatory response in preterm infants with respiratory distress syndrome (RDS)

Volutrauma and pulmonary inflammation are thought to be the most important predisposing factors of chronic lung disease (CLD), a major complication of prematurity. A new option in patient-triggered ventilation (PTV), the volume guarantee (VG), a volume-targeted ventilation, seems to be a promising approach in reducing the risk of CLD, by limiting lung inflammatory injury and volutrauma. Our aim was to evaluate lung inflammatory response in preterm infants with respiratory distress syndrome (RDS), mechanically ventilated with and without VG, as measured by proinflammatory cytokines (IL-6, IL-8, and TNF-alpha) in tracheobronchial aspirate (TA) fluid. Fifty-three preterm infants (GA = 25-32 weeks) with RDS were randomized at birth to be ventilated using pressure support ventilation (PSV) with VG (Vt = 5 ml/kg) (n = 30) and without VG (n = 23) (Draeger Babylog 8000 Plus, 5.n). IL-6, IL-8, and TNF-alpha were determined by ELISA in TA samples on days 1, 3, and 7 of life. We observed a significant difference (ANOVA) in IL-8 and IL-6 levels on day 3 between the two groups (P < 0.05), and an increasing significative trend in IL-8 values in PSV group (P < 0.05). Mechanical ventilation lasted longer in the PSV group (12.3 +/- 3 vs. 8.8 +/- 3 days) (P = no significance). In conclusion, these preliminary data suggest a role for volume-targeted ventilatory strategy in reducing acute inflammatory response in preterm infants with RDS. Further studies are required in order to define whether this ventilatory strategy prevents lung injury.

[Lung injury and ventilatory strategies]

Premature lungs are highly susceptible to lung injury induced by chorioamionitis, mechanical ventilation or persistent exposure to high O2 concentrations. The Authors linger on the central role of atelectrauma and volutrauma (by inadequate tidal volume-Vt) in course of mechanical ventilation of preterm infants with RDS. In particular, they evaluate the efficacy and safety of the targeted volume ventilation with the option of the Volume Guarantee (VG). For this reason they present the results of randomized clinical trials in preterm infants (25-32 wks of gestational age) with severe RDS, in mechanical ventilation, without VG or with two different VG (Vt = 3 or 5 ml/Kg). Data collected demonstrate a significative difference (p < 0.05) in terms od reduction of mean airway pressure (PAW), peak inspiratory pressure (PIP) and cytokines production (IL6-IL8 and TNF alfa) in tracheal aspirate fluid in preterm infants in synchronized ventilation with VG set at 5 ml/Kg. These preliminary results seem to demonstrate the protective role of targeted volume ventilation with Vt = 5 ml/Kg (minimal volutrauma with less lung inflammatory response), but without significative reduction of chronic lung disease (CLD) in this group (probably due to multifactorial pathogenesis of CLD).

[Cerebral oxygenation and near-infrared rays spectrophotometry]

Near infrared spectroscopy (NIRS) is a new technique which allows non invasive bedside monitoring of cerebral oxygenation and hemodynamics by measuring relative changes in cerebral oxy- and deoxyhaemoglobin and cytochrome aa3. We have applied this technique to evaluate the possible effects on cerebral oxygenation and hemodynamics of clinical procedures usually performed on preterm infants:--endotracheal suctioning, and we have demonstrated that the magnitude and the duration of the negative effects of open system are significantly reduced using closed endotracheal suctioning system;--withdrawal and infusion through umbilical vein and artery cause significant changes in cerebral hemodynamics: these effects are significantly reduced after administration of ibuprofen;--treatment of patent ductus arteriosus with ibuprofen does not significantly reduce cerebral perfusion and oxygen availability compared to indomethacin and ibuprofen administration also does not affect cerebral vasoreactivity to arterial carbon dioxide tension;--administration of different types and doses of natural surfactant causes different changes in cerebral hemodynamics and these effects seem to be dose-related. Therefore NIRS is an useful device to investigate cerebral oxygenation state of preterm infants and new possibilities could derive from the introduction of a new NIRS method which allows to measure the tissue oxygenation index.

Anti-tumor immunity induced by murine melanoma cells transduced with the Mycobacterium tuberculosis gene encoding the 38-kDa antigen

The Mycobacterium tuberculosis Ag38 gene, which encodes a highly immunogenic protein, was cloned into a retroviral vector in-frame with the leader and the transmembrane portion of the nerve growth factor receptor, and transduced into murine melanoma cell line B16-B78. Significant protection was observed in mice immunized with the transduced melanoma cells and subcutaneously challenged with parental melanoma cells since only 20% of mice developed tumors. Necroscopy of mice immunized with the transduced melanoma cells revealed dramatic inhibition of experimental metastases induced by intravenous (i.v.) inoculation of parental melanoma cells. Moreover, vaccination with transduced cells significantly prolonged survival of mice challenged i.v. with parental melanoma cells. These data indicate that the presence of the mycobacterial 38-kDa protein greatly enhances immunological recognition of structures expressed by the parental melanoma cells. Comparison of Th1 and Th2 responses in mice immunized with parental melanoma cells versus mice receiving the transduced cells revealed a clear predominance of Th1 responses when the Ag38 protein was endogenously expressed. This transduction approach may represent a promising immunotherapeutic strategy for the treatment of cancer patients.

A linear region of a monoclonal antibody conformational epitope mapped on p185HER2 oncoprotein

Analysis of epitopes recognized by therapeutic monoclonal antibodies (mAb) is critical in clinical applications and in structure/function studies of target antigen. mAb MGr6 recognizes the extracellular domain of the p185HER2 oncoprotein and is a promising candidate for cancer immunodiagnosis and immunotherapy. Thus, epitope location and structure on p185HER2 need to be investigated. The use of MGr6-selected phage-displayed peptides for epitope analysis served to dissect the MGr6 epitope into at least two subregions, mimicked by CHSDC- and (L)P-(L)K(L) phage displayed peptides, respectively. Comparison of amino acid sequences of CHSDC peptides with the p185HER2 protein sequence and analysis of MGr6 reactivity with p185HER2 deletion mutants identified the linear subregion CCHEQCAAG of the MGr6 epitope, corresponding to amino acids 235-243 of the p185HER2 protein. This continuous subregion is part of a larger conformational epitope, and other amino acids, including a proline, a lysine and leucine residues contained in (L)P-(L)K(L) phage-displayed peptides appear to contribute to the formation of the MGr6 epitope surface.

Closed versus open endotracheal suctioning in preterm infants: effects on cerebral oxygenation and blood volume

The aim of our study was to compare, using near-infrared spectroscopy (NIRS), the effects on cerebral intracellular oxygenation and cerebral blood volume (CBV) of closed endotracheal suctioning (CS), which permits continuous ventilation of the patient, with open endotracheal suctioning (OS), which requires disconnection from the ventilator. Eleven preterm infants were studied. Each patient underwent one CS, followed, after 60 min, by one OS, or vice versa, three times during the same day. Modifications in CBV and oxidized cytochrome oxidase (CytO2) were continuously detected by NIRS; arterial oxygen saturation (SaO2) heart rate (HR), transcutaneous carbon dioxide tension and mean arterial blood pressure were simultaneously recorded. Significant reductions in HR and SaO2 were observed following OS; the magnitude and duration of these negative effects of suctioning were significantly reduced with CS. In addition, the decrease in CBV was more pronounced than following CS. No changes in CytO2 concentration were seen.

Advantages of prenatal diagnosis and early surgery for congenital cystic disease of the lung

Prenatal ultrasonography makes possible the diagnosis of congenital cystic lung disease in utero, enabling elective surgery for the lesions early in infancy before development of respiratory distress or potentially life-threatening infection. From 1986 to 1994, ten infants with congenital lung cyst underwent corrective surgery. Nine of them had a prenatal diagnosis of congenital lung cyst confirmed by ultrasound or computed tomography (CT) after birth. In 7 of these infants, congenital adenomatoid malformation (CAM) was found at surgery, and pulmonary sequestration was found and removed in two other infants. Two of the nine infants had respiratory distress at birth; the seven others were asymptomatic when surgery was performed (between 2 and 6 months of age). In 4 out of 9 newborn a plain chest radiography at birth was normal and a CT scan only showed the cysts prenatally observed at ultrasound. Intraoperative measurement of pulmonary function in the asymptomatic infants demonstrated significant improvement after resection of the affected lobe. One other infant had normal lung fields at the time of prenatal diagnosis. However, a severe acute pneumonia with abscess of the lobe became life-threatening at 4.5 months. CT showed a large congenital lung cyst, treated initially with antibiotics and extirpated at age 6 months with great difficulty. Pulmonary function did not improve postoperatively. Examinations on follow-up (8 months-8 years; 5 of 10 infants longer than 4 years) have shown that all 10 of the infants are healthy and have normal pulmonary function. Pneumonia in the controlateral lung was found in 3 children (3-6 years after the operation), one of them had respiratory distress at birth and another had the life-threatening pneumonia preoperatively. Thus, early surgery is indicated when prenatal diagnosis of congenital cystic disease has been confirmed after birth.

Antibody transport and internalization into tumours

Internalization of monoclonal antibody (MAb) conjugates is an important feature of tumour targeting, both with respect to the therapeutic action of substances coupled to the antibody and to retention of radionuclides. Problems of analysing internalization in vitro and in vivo, of manipulating internalization, and of evaluating the involvement of normal tissues are illustrated by recent experimental data and are discussed in the light of published evidence.