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Background and Objectives: Nasal intermittent positive pressure ventilation (NIPPV) has been shown to be superior to nasal continuous positive airway pressure (CPAP) postextubation in preterm neonates. However, studies have not permitted high CPAP pressures or rescue with other modes. We hypothesized that if CPAP pressures >8 cmH2O and rescue with other modes were permitted, CPAP would be noninferior to NIPPV., Methods: We conducted a pragmatic, comparative-effectiveness, noninferiority study utilizing network-based real-world data from 22 Canadian NICUs. Centers self-selected CPAP or NIPPV as their standard postextubation mode for preterm neonates <29 weeks' gestation. The primary outcome was failure of the initial mode ≤72 hours. Secondary outcomes included failure ≤7 days, and reintubation ≤72 hours and ≤7 days. Groups were compared using a noninferiority adjusted risk-difference (aRD) margin of 0.05, and margin of no difference., Results: A total of 843 infants extubated to CPAP and 974 extubated to NIPPV were included. CPAP was not noninferior (and inferior) to NIPPV for failure of the initial mode ≤72 hours (33.0% vs 26.3%; aRD 0.07 [0.03 to 0.12], Pnoninferiority(NI) = .86), and ≤7 days (40.7% vs 35.8%; aRD 0.09 [0.05 to 0.13], PNI = 0.97). However, CPAP was noninferior (and equivalent) to NIPPV for reintubation ≤72 hours (13.2% vs 16.1%; aRD 0.01 [-0.05 to 0.02], PNI < .01), and noninferior (and superior) for reintubation ≤7 days (16.4% vs 22.8%; aRD -0.04 [-0.07 to -0.001], PNI < .01)., Conclusions: CPAP was not noninferior to NIPPV for failure ≤72 hours postextubation; however, it was noninferior to NIPPV for reintubation ≤72 hours and ≤7 days. This suggests CPAP may be a reasonable initial postextubation mode if alternate rescue strategies are available., (Copyright © 2024 by the American Academy of Pediatrics.)

The aim of this retrospective cohort study was to study the clinical burden associated with cardio-pulmonary critical decompensations (CPCDs) in preterm neonates and factors associated with mortality. Through the Canadian Neonatal Network (30 tertiary NICUs, 2010-2017), we identified infants < 32-week gestational age with CPCDs, defined by "significant exposure" to cardiotropes and/or inhaled nitric oxide (iNO): (1) either therapy for ≥ 3 consecutive days, (2) both for ≥ 2 consecutive days, or (3) any exposure within 2 days of death. Early CPCDs (≤ 3 days of age) and late CPCDs (> 3 days) were examined separately. Outcomes included CPCD-incidence, mortality, and inter-site variability using standardized ratios (observed/adjusted expected rate) and network funnel plots. Mixed-effects analysis was used to quantify unit-level variability in mortality. Overall, 10% of admissions experienced CPCDs (n = 2915). Late CPCDs decreased by ~ 5%/year, while early CPCDs were unchanged during the study period. Incidence and CPCD-associated mortality varied between sites, for both early (0.6-7.5% and 0-100%, respectively) and late CPCDs (2.5-15% and 14-83%, respectively), all p < 0.01. Units' late-CPCD incidence and mortality demonstrated an inverse relationship (slope =  -2.5, p < 0.01). Mixed-effects analysis demonstrated clustering effect, with 6.4% and 8.6% of variability in mortality after early and late CPCDs respectively being site-related, unexplained by available patient-level characteristics or unit volume. Mortality was higher with combined exposure than with only-cardiotropes or only-iNO (41.3%, 24.8%, 21.5%, respectively; p < 0.01)., Conclusions: Clustering effects exist in CPCD-associated mortality among Canadian NICUs, with higher incidence units showing lower mortality. These data may aid network-level benchmarking, patient-level risk stratification, parental counseling, and further research and quality improvement work., What Is Known: • Preterm neonates remain at high risk of acute and chronic complications; the most critically unwell require therapies such as cardiotropic drugs and inhaled nitric oxide. • Infants requiring these therapies are known to be at high risk for adverse neonatal outcomes and for mortality., What Is New: • This study helps illuminate the national burden of acute cardio-pulmonary critical decompensation (CPCD), defined as the need for cardiotropic drugs or inhaled nitric oxide, and highlights the high risk of morbidity and mortality associated with this disease state. • Significant nationwide variability exists in both CPCD incidence and associated mortality; a clustering effect was observed with higher incidence sites showing lower CPCD-associated mortality., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: To compare neurodevelopmental outcomes of large and appropriate for gestational age (LGA, AGA) infants <29 weeks' gestation at 18-24 months of corrected age., Study Design: Retrospective cohort study using the Canadian Neonatal Network and Canadian Neonatal Follow-Up Network databases. Primary outcome was a composite of death or significant neurodevelopmental impairment (NDI), defined as severe cerebral palsy, Bayley III cognitive, language and motor scores of <70, need for hearing aids or cochlear implant and bilateral visual impairment. Univariate and multivariable logistic analyses were applied for outcomes., Results: The study cohort comprised 170 LGA and 1738 AGA infants. There was no difference in significant NDI or individual components of the Bayley III between LGA and AGA groups. LGA was associated with the increased risk of death by follow-up, 44/170 (25.9%) vs. 320/1738 (18.4%) (aOR: 1.60 95% CI: 1.00-2.54)., Conclusions: Risk of NDI was similar between LGA and AGA infants.

Background: One of the controversies in the management of twin gestations relates to mode of delivery, especially when the second twin is in a nonvertex presentation (Vertex/nonVertex pairs) and birth is imminent at extremely low gestation., Objective: We hypothesized that, for Vertex/nonVertex twins born before 28 weeks' gestation, cesarean delivery would be associated with a lower risk of adverse neonatal outcomes than trial of vaginal delivery. Our aim was to test this hypothesis by comparing the neonatal outcomes of Vertex/nonVertex twins born before 28 weeks' gestation by mode of delivery using a large national cohort., Study Design: This work is a retrospective cohort study of all twin infants born at 24 0/7 to 27 6/7 weeks' gestation and admitted to level III neonatal intensive care units participating in the Canadian Neonatal Network (2010-2017). Exposure is defined a trial of vaginal delivery for Vertex/nonVertex twins. Nonexposed (control) groups are defined as cases where both twins were delivered by cesarean delivery, either in vertex or nonvertex presentation (control group 1) or owing to the nonvertex presentation of the first twin (control group 2). Outcome measures are defined as a composite of neonatal death, severe neurologic injury, or birth trauma., Results: A total of 1082 twin infants (541 twin pairs) met the inclusion criteria: 220 Vertex/nonVertex pairs, of which 112 had a trial of vaginal delivery (study group) and 108 had cesarean delivery for both twins (control group 1); 170 pairs with the first twin in nonvertex presentation, all of which were born by cesarean delivery (control group 2); and 151 pairs with both twins in vertex presentation (vertex or nonvertex). In the study group, the rate of urgent cesarean delivery for the second twin was 30%. The rate of the primary outcome in the study group was 42%, which was not significantly different compared with control group 1 (37%; adjusted relative risk, 0.93; 95% confidence interval, 0.71-1.22) or control group 2 (34%; adjusted relative risk, 1.20; 95% confidence interval, 0.92-1.58). The findings remained similar when outcomes were analyzed separately for the first and second twins., Conclusion: For preterm Vertex/nonVertex twins born at <28 weeks' gestation, we found no difference in the risk of adverse neonatal outcome between a trial of vaginal delivery and primary cesarean delivery. However, a trial of vaginal delivery was associated with a high rate of urgent cesarean delivery for the second twin., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Competing Interests: Competing interests: None declared.

Tumors induce their heterogeneous vasculature by secreting vascular endothelial growth factor (VEGF)-A. Anti-VEGF/VEGF receptor (VEGFR) drugs treat cancer, but the underlying mechanisms remain unclear. An adenovirus expressing VEGF-A (Ad-VEGF-A 164 ) replicates the tumor vasculature in mice without tumor cells. Mother vessels (MV) are the first angiogenic vessel type to form in tumors and after Ad-VEGF-A 164 . Multiday treatments with a VEGF trap reverted MV back to normal microvessels. We now show that, within hours, a single dose of several anti-VEGF drugs collapsed MV to form glomeruloid microvascular proliferations (GMP), accompanied by only modest endothelial cell death. GMP, common in many human cancers but of uncertain origin, served as an intermediary step in MV reversion to normal microvessels. The vasodisruptive drug combretastatin CA4 also targeted MV selectively but acted differently, extensively killing MV endothelium. Antivascular changes were quantified with a novel Evans blue dye assay that measured vascular volumes. As in tumors, Ad-VEGF-A 164 strikingly increased endothelial nitric oxide synthase (eNOS) expression. The eNOS inhibitor N(G)-Nitro-l-arginine methyl ester mimicked anti-VEGF/VEGFR drugs, rapidly collapsing MV to GMP. Inhibition of eNOS reduces synthesis of its vasodilatory product, nitric oxide, leading to arterial contraction. Patients and mice receiving anti-VEGF/VEGFR drugs develop hypertension, reflecting systemic arterial contraction. Together, anti-VEGF/VEGFR drugs act in part by inhibiting eNOS, causing vasocontraction, MV collapse to GMP, and subsequent reversion of GMP to normal microvessels, all without extensive vascular killing., (Copyright © 2017 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

A 63-year-old Caucasian woman developed severe Plasmodium falciparum malaria when travelling back from Cameroun. No antimalarial chemoprophylaxis had been observed. The patient was immediately admitted to the intensive care unit after evidence of multiple organ failure (coma, shock, acute respiratory distress syndrome, acute renal failure, etc.). However, initial parasitemia was less than 1%. The patient was managed by intravenous quinine and norepinephrine infusion due to refractory shock. The patient developed as an early complication ischemic lesions of both arms and feet. In addition to laboratory changes consistent with disseminated intravascular coagulation, there was also evidence for a low activity of the von Willebrand factor (VWF) cleaving protease ADAMTS13. Later complications included repeated candidemia and bacteraemia despite appropriate therapy; the origin appeared to be diffuse ischemic injury of the gastrointestinal tract. The patient ultimately recovered, but quadriamputation was necessary to treat symmetrical peripheral gangrene (SPG). In severe Plasmodium falciparum malaria, ischemic changes may be due to microvascular obstruction, but, in patients with low parasitemia, other endothelial factors may also be involved as observed in other groups of thrombotic microangiopathies.

We have used our previously described ex vivo mesothelial cell (MC)-mediated gene therapy strategy (Gene Ther. 2:393-401, 1995) to modify the functional properties of the rat parietal peritoneal mesothelium in vivo by expression of a membrane-bound recombinant protein on the MC surface. Rat primary MCs were stably transfected (using strontium phosphate DNA coprecipitation) with a plasmid containing the gene for rat thrombomodulin (TM), a transmembrane glycoprotein that functions as an essential cofactor for the physiological activation of the anticoagulant protein C by the enzyme thrombin. As demonstrated by immunohistochemistry and by direct equilibrium binding with radiolabeled thrombin, genetically modified MCs expressed high levels of TM antigen on their surface in vitro. As judged by a thrombin-dependent protein C activation assay, such MC membrane-bound TM was biologically active. Once reseeded on the denuded parietal peritoneal surface of syngeneic recipients, these TM-transfected MCs continued to express TM antigen in vivo for at least 90 days. Moreover, the recombinant TM expressed on the reconstituted parietal mesothelium retained its ability to activate protein C in a thrombin-dependent manner. Our data indicate that MC-mediated expression of TM can be used to augment the anticoagulant properties of the parietal peritoneal surface. In general, our results suggest that ex vivo MC-mediated gene therapy can be used to deliver other therapeutic transmembrane proteins to the MC surface to enhance the functional repertoire of the parietal mesothelium in vivo.

To evaluate the ability of genetically modified peritoneal mesothelial cells to deliver recombinant proteins to the systemic circulation, we used our previously described mesothelial cell-based ex vivo gene therapy strategy. Rat primary peritoneal mesothelial cells, isolated from parietal peritoneum by enzymatic digestion, were stably transfected (using strontium phosphate DNA co-precipitation) with the plasmid pSVTKgh to express a secreted reporter gene product, human growth hormone (hgh). Such hgh-secreting mesothelial cells were reseeded on the denuded peritoneal surface of syngeneic recipients and delivery of the reporter gene product to the systemic circulation was monitored by analysis of serum samples for the presence of hgh at various times after mesothelial cell implantation. Polymerase chain reaction (PCR) analysis demonstrated that the hgh-transfected mesothelial cells repopulated the denuded areas and remained attached there for at least 12 weeks. Moreover, these genetically modified mesothelial cells continued to express the reporter gene product in vivo and secreted hgh in sufficient quantity to be detected in the systemic circulation (ie statistically significant amounts of hgh could be measured in the serum of cyclosporine A-treated rats for at least 2 months; Mann-Whitney test, P < 0.05). Our results demonstrate the successful, sustained, systemic delivery of a recombinant protein by genetically modified peritoneal mesothelial cells following their reattachment to the peritoneal surface, and suggest the potential of ex vivo mesothelial cell-mediated gene therapy for the treatment of inherited or acquired disorders requiring delivery of therapeutic proteins to the circulation.

We have developed a model system in the rat to test the feasibility of recombinant protein expression by genetically modified peritoneal mesothelial cells following autologous peritoneal implantation. Rat primary peritoneal mesothelial cells, isolated from parietal peritoneum by enzymatic digestion, were stably transduced (using a Moloney murine leukemia virus (MoMLV)-derived retroviral vector, BAG, expressing the Escherichia coli lacZ gene) to mark the cells with a reporter protein (beta-galactosidase, beta-gal). Such transduced mesothelial cells, tagged with DiO, a fluorescent lipophilic dye used for long-term tracing of transplanted cells, were then reseeded on the denuded peritoneal surface of syngeneic recipients. DiO-labeled, BAG-transduced mesothelial cells were observed to repopulate the denuded areas and remain attached there for > 90 days. Moreover, these genetically modified mesothelial cells continued to express the reporter gene product in vivo (ie beta-gal activity was present for at least 1 month). Our results demonstrate the feasibility of ex vivo gene therapy using peritoneal mesothelial cells.

Previous studies have shown that accumulation of tumor ascites fluid results in large part from increased permeability of peritoneal lining vessels (Nagy et al., Cancer Res., 49: 5449-5458, 1989; Nagy et al., Cancer Res., 53: 2631-2643, 1993). However, the specific microvessels rendered hyperpermeable have not been identified nor has the basis of peritoneal vascular hyperpermeability been established. To address these questions, TA3/St and MOT carcinomas, well-characterized transplantable murine tumors that grow in both solid and ascites form, were studied as model systems. Ascites tumor cells of either type were injected i.p. into syngeneic A/Jax and C3Heb/FeJ mice, and ascites fluid and plasma were collected at intervals thereafter up to 8 and 28 days, respectively. Beginning several days after tumor cell injection, small blood vessels located in tissues lining the peritoneal cavity (mesentery, peritoneal wall, and diaphragm) became hyperpermeable to several macromolecular tracers (125I-human serum albumin, FITC-dextran, colloidal carbon, and Monastral Blue B). Increased microvascular permeability correlated with the appearance in ascites fluid of vascular permeability factor (VPF), a tumor cell-secreted mediator that potently enhances vascular permeability to circulating macromolecules. VPF was measured in peritoneal fluid by both a functional bioassay and a sensitive immunofluorometric assay. The VPF concentration, total peritoneal VPF, ascites fluid volume, tumor cell number, and hyperpermeability of peritoneal lining microvessels were found to increase in parallel over time. The close correlation of peritoneal fluid VPF concentration with the development of hyperpermeable peritoneal microvessels in these two well-defined ascites tumors suggests that VPF secretion by tumor cells is responsible, in whole or in part, for initiating and maintaining the ascites pattern of tumor growth.

In the immediately preceding paper, we demonstrated that the microvasculature supplying peritoneal lining tissues of mice bearing either of two transplantable ascites carcinomas was hyperpermeable to circulating macromolecules. Solid tumors have been shown to exhibit similar levels of microvascular hyperpermeability, leading to extravasation of plasma proteins, including fibrinogen which clots on extravasation to form an extravascular fibrin gel. To determine whether similar extravasation and clotting of plasma fibrinogen occurred in ascites tumors, we used 125I-labeled fibrinogen (125I-F) as a tracer to measure inflow of fibrinogen into the peritoneal cavities, and influx and accumulation of fibrinogen/fibrin in the peritoneal lining tissues (peritoneal wall, mesentery, and diaphragm) of mice bearing syngeneic TA3/St or MOT ascites tumors. The percentage of circulating 125I-F that extravasated into the peritoneal cavity was increased from 10- to 50-fold in mice bearing either ascites tumor. Influx into the peritoneal walls of ascites tumor-bearing mice was 3-7 times that of control mice and became maximal on day 8 (TA3/St) and day 15 (MOT). Accumulation of 125I-F in ascites fluid and peritoneal lining tissues was also increased substantially in mice bearing these ascites tumors, reaching maximal values on days 7-8 (TA3/St) and 19-29 (MOT) at levels 2- to 3-fold (peritoneal wall) and 33- to 148-fold (ascites fluid) above control levels. Significant amounts of the 125I-F that accumulated in the peritoneal lining tissues of ascites tumor-bearing animals were insoluble in 3 M urea, consistent with clotting of 125I-F to cross-linked fibrin. Autoradiographs of SDS-PAGE gels performed on extracts of peritoneal lining tissues of both ascites tumors revealed the characteristic signature of cross-linked fibrin, i.e., gamma-gamma dimers and alpha-polymers. Fibrin was also identified in peritoneal lining tissues of both ascites tumors by immunohistochemistry. Taken together, these data indicate that fibrinogen, like other circulating macromolecules, extravasates into the peritoneal cavity and peritoneal lining tissues of ascites tumor-bearing mice and does so with kinetics similar to those of other macromolecular tracers we have studied. Moreover, a portion of the fibrinogen that extravasated into peritoneal lining tissues clotted to form a cross-linked fibrin meshwork which trapped tumor cells and favored their attachment to the peritoneal surface. By analogy with solid tumors, such fibrin deposits may also be expected to have a role in initiating angiogenesis and the generation of mature tumor stroma.

Vascular permeability factor (VPF), also known as vascular endothelial growth factor, is a dimeric M(r) 34,000-42,000 glycoprotein that possesses potent vascular permeability-enhancing and endothelial cell-specific mitogenic activities. It is synthesized by many rodent and human tumor cells and also by some normal cells. Recently we developed a sensitive and specific time-resolved immunofluorometric assay for quantifying VPF in biological fluids. We here report findings with this assay in guinea pigs and patients with both malignant and nonmalignant effusions. Line 1 and line 10 tumor cells were injected into the peritoneal cavities of syngeneic strain 2 guinea pigs, and ascitic fluid, plasma, and urine were collected at various intervals. Within 2 to 4 days, we observed a time-dependent, parallel increase in VPF, ascitic fluid volume, and tumor cell numbers in animals bearing either tumor line; in contrast, VPF was not detected in plasma or urine, even in animals with extensive tumor burdens. However, low levels of VPF were detected in the inflammatory ascites induced by i.p. oil injection. In human studies, high levels of VPF (> 10 pM) were measured in 21 of 32 effusions with cytology-documented malignant cells and in only seven of 35 effusions without cytological evidence of malignancy. Thus, VPF levels in human effusions provided a diagnostic test for malignancy with a sensitivity of 66% and a specificity of 80% (perhaps as high as 97% in that six of the seven cytology-negative patients with VPF levels > 10 pM had cancer as determined by other criteria). As in the animal tumor models, VPF was not detected in serum or urine obtained from patients with or without malignant ascites. Many nonmalignant effusions contained measurable VPF but, on average, in significantly smaller amounts than were found in malignant effusions. VPF levels in such fluids correlated strongly (p = 0.59, P < 0.001) with monocyte and macrophage content. Taken together, these data relate ascitic fluid accumulation to VPF concentration in a well-defined animal tumor system and demonstrate, for the first time, the presence of VPF in human malignant effusions. It is likely that VPF expression by tumor and mononuclear cells contributes to the plasma exudation and fluid accumulation associated with malignant and certain inflammatory effusions. The VPF assay may prove useful for cancer diagnosis as a supplement to cytology, especially in tumors that grow in the pleural lining but not as a suspension in the effusions that they induce.

Fluorescein-labeled dextrans (FITC-D) from 3 to 5000 kDa (Stokes' radii from 1 to 40 nm) were used to study influx from the plasma into the peritoneum and efflux from the peritoneal cavity into the plasma in normal and ascites tumor-bearing mice and in mice whose peritoneal vessels had been rendered hyperpermeable by serotonin. Two syngeneic transplantable murine ascites tumors were studied: mouse ovarian tumor and the TA3/St breast adenocarcinoma. To control for effects of peritoneal fluid volume, influx and efflux were also analyzed in mice that had received 5 ml of 5% bovine serum albumin i.p. as "artificial ascites." Following i.v. or i.p. injection, levels of FITC-D in the plasma and peritoneal fluid were quantitated by fluorimetry at successive time intervals from 5 to 360 min posttracer injection. Influx and efflux data were analyzed with a model consisting of three compartments (plasma, peritoneal cavity, and the extravascular space of all other organs) to yield kinetic parameters that characterized macromolecular transport. Depending on the size of the FITC-D tracer, from 3- to 50-fold more FITC-D accumulated in mouse ovarian tumor or TA3/St tumor ascites fluid, and 3- to 10-fold more FITC-D accumulated in the peritoneum of serotonin-treated than normal mice, all of it intact by gel exclusion chromatography. Influx of the FITC-D from plasma into the peritoneum, as characterized by the rate constant k1, was 2- to 40-fold greater in ascites tumor-bearing animals and 2- to 10-fold greater in serotonin-treated animals than in controls. Control animals with artificial ascites showed at most a 4-fold increase in the value of k1. As judged by fluorescence microscopy, the permeability of peritoneal-lining vessels in ascites tumor-bearing animals was greatly increased to FITC-D of 70 to 5000 kDa. Efflux of FITC-D, characterized by the rate constant k2, was reduced from 5- to 50-fold in ascites tumor-bearing animals but was unchanged or actually somewhat enhanced following serotonin treatment. Efflux in animals that had received artificial ascites was reduced 2.5- to 12.5-fold, correlating increased peritoneal fluid volume with decreased efflux. We conclude that tracer accumulation in malignant ascites fluid results from both increased influx as well as impaired efflux. Influx, and to a lesser extent efflux, were significantly affected by tracer size. However, within the range of FITC-D tested, we found no absolute size barrier to macromolecular transport from plasma to the peritoneal cavity, or vice versa.(ABSTRACT TRUNCATED AT 400 WORDS)