The paradox of tPA in ischemic stroke: tPA knockdown following recanalization improves functional and histological outcomes.

Previous studies have demonstrated that endogenous tissue-type plasminogen activator (tPA) is upregulated in the brain after an acute ischemic stroke (AIS). While mixed results were observed in genetic models, the pharmacological inhibition of endogenous tPA showed beneficial effects. Treatment with exogenous recombinant tPA exacerbated brain damage in rodent models of stroke. Despite the detrimental effects of tPA in ischemic stroke, recombinant tPA is administered to AIS patients to recanalize the occluded blood vessels because the benefits of its administration outweigh the risks associated with tPA upregulation and increased activity. We hypothesized that tPA knockdown following recanalization would ameliorate sensorimotor deficits and reduce brain injury. Young male and female rats (2-3 months old) were subjected to transient focal cerebral ischemia by occlusion of the right middle cerebral artery. Shortly after reperfusion, rats from appropriate cohorts were administered a nanoparticle formulation containing tPA shRNA or control shRNA plasmids (1 mg/kg) intravenously via the tail vein. Infarct volume during acute and chronic phases, expression of matrix metalloproteinases (MMPs) 1, 3, and 9, enlargement of cerebral ventricle volume, and white matter damage were all reduced by shRNA-mediated gene silencing of tPA following reperfusion. Additionally, recovery of somatosensory and motor functions was improved. In conclusion, our results provide evidence that reducing endogenous tPA following recanalization improves functional outcomes and reduces post-stroke brain damage.

The Impact of Social Isolation and Environmental Deprivation on Blood Pressure and Depression-Like Behavior in Young Male and Female Mice.

Background: Social isolation (SI) and loneliness are major adult and adolescent health concerns, particularly in the coronavirus disease 2019 (COVID-19) era. Recent prospective cohort studies indicate that older women who experienced both SI and loneliness had a significantly higher risk of cardiovascular disease (CVD). Hypertension, a well-established risk factor for CVD, is more prevalent in elderly women than men. Furthermore, a lack of social relationships is strongly associated with an increased risk of hypertension in middle-aged and elderly women compared to men. Although this has not been extensively studied, adolescents and young adults who experience loneliness or SI may also be at risk for CVD and depression. The purpose of this study was to examine the effect of SI on blood pressure and depression-like behavior in young male and female mice. Methods: Weaned C57BL/6 mice were randomly assigned (n = 6/group/sex) to either group housing (GH) or SI. Animals in the SI group were housed in individual cages for 8 weeks with no view of other animals. The cages were kept in ventilated racks to prevent pheromone exposure and socially isolated animals had no cage enrichment. Results: SI increased systolic, diastolic, and mean arterial blood pressure in females and elevated heart rate in both sexes. Body weight gain was dramatically increased in socially isolated females but tended to decrease in socially isolated males. In the forced swim test, which detects depression-like behavior, there was no difference between groups in total immobility time. The latency to immobility, however, was significantly decreased in socially isolated females. Serum concentrations of corticosterone and metanephrine did not differ between socially isolated and group-housed females, but corticosterone levels were significantly reduced in socially isolated males. Conclusions: Our results indicate that 8 weeks of SI leads to significant changes in blood pressure and heart rate and mild changes in depression-like behavior in young mice, with females affected more than males.

Relationship of Post-Transplant Lymphoproliferative Disorders (PTLD) Subtypes and Clinical Outcome in Pediatric Heart Transplant Recipients: A Retrospective Single Institutional Analysis/Experience of 558 Patients.

Post-transplant lymphoproliferative disorders (PTLD) are heterogenous lymphoproliferative disorders that develop as a consequence of immunosuppression in transplant recipients. We sought to determine if subtypes of PTLD correlated with different outcomes. We performed a retrospective review of PTLD occurring in pediatric heart transplant recipients. A total of 558 children and infants underwent cardiac transplantation at our institution between 1985 and 2019 and were followed until March 2021. Forty-nine of 558 patients developed PTLD (8.8%). As compared to older children (>one year of age), infant recipients (

Therapeutic efficacy of matrix metalloproteinase-12 suppression on neurological recovery after ischemic stroke: Optimal treatment timing and duration.

We recently showed that the post-ischemic induction of matrix metalloproteinase-12 (MMP-12) in the brain degrades tight junction proteins, increases MMP-9 and TNFα expression, and contributes to the blood-brain barrier (BBB) disruption, apoptosis, demyelination, and infarct volume development. The objectives of this study were to (1) determine the effect of MMP-12 suppression by shRNA-mediated gene silencing on neurological/functional recovery, (2) establish the optimal timing of MMP-12shRNA treatment that provides maximum therapeutic benefit, (3) compare the effectiveness of acute versus chronic MMP-12 suppression, and (4) evaluate potential sex-related differences in treatment outcomes. Young male and female Sprague-Dawley rats were subjected to transient middle cerebral artery occlusion and reperfusion. Cohorts of rats were administered either MMP-12shRNA or scrambled shRNA sequence (control) expressing plasmids (1 mg/kg; i.v.) formulated as nanoparticles. At designated time points after reperfusion, rats from various groups were subjected to a battery of neurological tests to assess their reflex, balance, sensory, and motor functions. Suppression of MMP-12 promoted the neurological recovery of stroke-induced male and female rats, although the effect was less apparent in females. Immediate treatment after reperfusion resulted in a better recovery of sensory and motor function than delayed treatments. Chronic MMP-12 suppression neither enhanced nor diminished the therapeutic effects of acute MMP-12 suppression, indicating that a single dose of plasmid may be sufficient. We conclude that suppressing MMP-12 after an ischemic stroke is a promising therapeutic strategy for promoting the recovery of neurological function.

The interplay between MMP-12 and t-PA in the brain after ischemic stroke.

Tissue-type plasminogen activator (t-PA) expression is known to increase following transient focal cerebral ischemia and reperfusion. Previously, we reported downregulation of t-PA upon suppression of matrix metalloproteinase-12 (MMP-12), following transient focal cerebral ischemia and reperfusion. We now present data on the temporal expression of t-PA in the brain after transient ischemia, as well as the interaction between MMP-12 and t-PA, two proteases associated with the breakdown of the blood-brain barrier (BBB) and ischemic brain damage. We hypothesized that there might be reciprocal interactions between MMP-12 and t-PA in the brain after ischemic stroke. This hypothesis was tested using shRNA-mediated gene silencing and computational modeling. Suppression of t-PA following transient ischemia and reperfusion in rats attenuated MMP-12 expression in the brain. The overall effect of t-PA shRNA administration was to attenuate the degradation of BBB tight junction protein claudin-5, diminish BBB disruption, and reduce neuroinflammation by decreasing the expression of the microglia/macrophage pro-inflammatory M1 phenotype (CD68, iNOS, IL-1ß, and TNFα). Reduced BBB disruption and subsequent lack of infiltration of macrophages (the main source of MMP-12 in the ischemic brain) could account for the decrease in MMP-12 expression after t-PA suppression. Computational modeling of in silico protein-protein interactions indicated that MMP-12 and t-PA may interact physically. Overall, our findings demonstrate that MMP-12 and t-PA interact directly or indirectly at multiple levels in the brain following an ischemic stroke. The present findings could be useful in the development of new pharmacotherapies for the treatment of stroke.

Comparison of Local and Systemic Inflammation During Invasive Versus Noninvasive Ventilation in Rats.

The impact of noninvasive ventilation (NIV) on local and systemic inflammation is poorly characterized, particularly when compared with invasive mechanical ventilation (IMV). We sought to quantify the local and systemic inflammatory response of these 2 respiratory treatments in rats with lipopolysaccharide (LPS)-induced lung injury (LPS-injured) and healthy rats. Animals were subjected to 4 h of NIV or IMV treatments at noninjurious settings, or 4 h of control treatment in which healthy or LPS-injured animals remained spontaneously breathing under isoflurane anesthesia with no respiratory support. Cytokines were then quantified in the serum and lung tissue by multiplex enzyme-linked immunosorbent assay. Contrary to our hypothesis, there were no significant differences in cytokine levels in serum or lung when comparing the NIV- and IMV-treated groups; this was true in both LPS-injured and healthy rats. However, within the LPS-injured group, pulmonary levels of interleukin (IL)-1α, IL-6, and tumor necrosis factor α were significantly lower in the NIV-treated group than in control but not in the IMV-treated group compared with control. We conclude that NIV, unlike IMV, could attenuate local inflammation.

Novel Multidisciplinary Management of Acute Kidney Injury After Infant Orthotopic Heart Transplantation.

Acute kidney injury following orthotopic heart transplantation in pediatric recipients is often multifactorial, requiring balance of immune suppression, nephrotoxic medication exposure, nutrition, and fluid status. Therapeutic options are often limited by patient size and hemodynamic stability. We describe a four-month, 4.9-kg female bridged by mechanical circulatory support to transplant after failed stage 1 palliation secondary to recurrent aortic stenosis and severe ventricular dysfunction. Posttransplant, kidney injury was managed by transcatheter relief of central obstruction from an anastomotic stricture and continuous renal replacement therapy, allowing uninterrupted immune suppression, medication, and nutrition delivery until sufficient recovery of renal function.

Clinical characteristics and outcomes associated with nasal intermittent mandatory ventilation in acute pediatric respiratory failure.

AIM: To characterize the clinical course and outcomes of nasal intermittent mandatory ventilation (NIMV) use in acute pediatric respiratory failure. METHODS: We identified all patients treated with NIMV in the pediatric intensive care unit (PICU) or inpatient general pediatrics between January 2013 and December 2015 at two academic centers. Patients who utilized NIMV with other modes of noninvasive ventilation during the same admission were included. Data included demographics, vital signs on admission and prior to initiation of NIMV, pediatric risk of mortality III (PRISM-III) scores, complications, respiratory support characteristics, PICU and hospital length of stays, duration of respiratory support, and complications. Patients who did not require escalation to mechanical ventilation were defined as NIMV responders; those who required escalation to mechanical ventilation (MV) were defined as NIMV non-responders. NIMV responders were compared to NIMV non-responders. RESULTS: Forty-two patients met study criteria. Six (14%) failed treatment and required MV. The majority of the patients (74%) had a primary diagnosis of bronchiolitis. The median age of these 42 patients was 4 mo (range 0.5-28.1 mo, IQR 7, P = 0.69). No significant difference was measured in other baseline demographics and vitals on initiation of NIMV; these included age, temperature, respiratory rate, O2 saturation, heart rate, systolic blood pressure, diastolic blood pressure, and PRISM-III scores. The duration of NIMV was shorter in the NIMV non-responder vs NIMV responder group (6.5 h vs 65 h, P < 0.0005). Otherwise, NIMV failure was not associated with significant differences in PICU length of stay (LOS), hospital LOS, or total duration of respiratory support. No patients had aspiration pneumonia, pneumothorax, or skin breakdown. CONCLUSION: Most of our patients responded to NIMV. NIMV failure is not associated with differences in hospital LOS, PICU LOS, or duration of respiratory support.

Use of two cleft lip and palate classification systems by nonsubspecialized health care providers.

Objective : The purpose of this experiment was to evaluate the use of RPL and LAHSHAL coding systems by individuals not specialized in craniofacial abnormalities to code cleft lip and palate (CLP). The effectiveness of system use by referring services and the electronic medical record (EMR) applicability of other CLP systems was evaluated by literature review and testing data. Design and Participants : The RPL and LAHSHAL systems were presented together to a sample of medical students (n = 28) and neonatal intensive care unit nurses (n = 24) from Loma Linda University. Following the presentation, a test assessing the application of each system was administered. A second assessment of the medical students (n = 23) 2 weeks after the initial presentation evaluated system retention. Scores were compared using t test (P ≤ .05). Results : Both the medical students and nurses used RPL more accurately than LAHSHAL in the first assessment (76.9% versus 45.2%, P < .001; 46.6% versus 22.5%, P < .001). Medical students again used RPL more accurately at the 2-week assessment (72.2% versus 43.7%, P < .001). Accuracy of use within each system was not significantly different between the two assessments. Conclusion : Our test results and literature review indicate that, when compared with LAHSHAL, RPL is more easily and accurately used by representatives not specialized in abnormalities in CLP; therefore, RPL may be a more effective system for nonspecialist health care providers to improve the accuracy of referrals and simple EMR documentation.