Use of an airway bundle to reduce unplanned extubations in a neonatal intensive care unit

BACKGROUND

Following the opening of an infant cardiac neonatal intensive care unit, our aim was to determine a baseline UE rate and implement initiatives to target a goal less than 0.5 UEs/100 ventilator days.

METHODS

We utilized the Model for Improvement. Key stakeholders included neonatal providers, nurses, and respiratory therapists. We focused on the creation of an airway bundle that addressed securement methods, communication and education.

RESULTS

From October 2017 to January 2018, our baseline UE rate was 0.92 UEs/100 ventilator days. Subsequent to the implementation of an airway bundle with high compliance, we observed a significant change in the centerline (0.45 to 0.02 UEs/100 ventilator days) during the spring of 2021, followed by a period of 480 days with no UEs.

CONCLUSION

In a unit where UEs were infrequent events, high compliance with an airway bundle led to a significantly sustained decrease in our UE rates.

Protocol for metadata and image collection at diabetic foot ulcer clinics: enabling research in wound analytics and deep learning

BACKGROUND

The escalating impact of diabetes and its complications, including diabetic foot ulcers (DFUs), presents global challenges in quality of life, economics, and resources, affecting around half a billion people. DFU healing is hindered by hyperglycemia-related issues and diverse diabetes-related physiological changes, necessitating ongoing personalized care. Artificial intelligence and clinical research strive to address these challenges by facilitating early detection and efficient treatments despite resource constraints. This study establishes a standardized framework for DFU data collection, introducing a dedicated case report form, a comprehensive dataset named Zivot with patient population clinical feature breakdowns and a baseline for DFU detection using this dataset and a UNet architecture.

RESULTS

Following this protocol, we created the Zivot dataset consisting of 269 patients with active DFUs, and about 3700 RGB images and corresponding thermal and depth maps for the DFUs. The effectiveness of collecting a consistent and clean dataset was demonstrated using a bounding box prediction deep learning network that was constructed with EfficientNet as the feature extractor and UNet architecture. The network was trained on the Zivot dataset, and the evaluation metrics showed promising values of 0.79 and 0.86 for F1-score and mAP segmentation metrics.

CONCLUSIONS

This work and the Zivot database offer a foundation for further exploration of holistic and multimodal approaches to DFU research.

A Call for Early Detection of Cerebral Palsy

Cerebral palsy (CP) is the most common physical disability across the lifespan, but historically, CP has not been diagnosed before the age of 2 years. Barriers to early diagnosis ranged from lack of available biomarkers, absence of curative treatments, perceived stigma associated with a lifelong diagnosis, and a desire to rule out other diagnoses first. Most importantly, the fundamental question that remained was whether children would benefit from earlier detection and intervention given the paucity of research. However, evidence-based guidelines published in 2017 demonstrated that the General Movements Assessment, the Hammersmith Infant Neurological Examination, and neuroimaging can be combined with other elements such as a clinical history and standardized motor assessments to provide the highest predictive value for diagnosing CP as early as age 3 months in high-risk newborns. Implementation of these guidelines has been successful in decreasing the age at CP diagnosis, particularly in high-risk infant follow-up clinics with expertise in performing these assessments. Early detection of CP allows for clinical and research opportunities investigating earlier interventions during a critical period of neuroplasticity, with the goal of improving developmental trajectories for children and their families. New guidelines and research are now being developed with a focus on early, targeted interventions that continue to be studied, along with global detection initiatives.

Association between intermittent hypoxemia and neurodevelopmental outcomes in extremely premature infants: A single-center experience

OBJECTIVE

To describe the association between intermittent hypoxemic events (IHEs) and severe neurodevelopmental impairment (SNDI) or death in extremely premature infants.

STUDY DESIGN

Retrospective study of extremely premature infants 230/7-276/7 weeks gestational age (GA) and birthweight (BW) ≤1250 grams (g) admitted to a level IV neonatal intensive care unit (NICU) from 2013 to 2017. IHEs, defined as events with SpO2 ≤ 80 % lasting 10 s to 5 min, were algorithmically identified using data extracted from bedside monitors at 2 s intervals (0.5 Hz). The primary outcome was SNDI at 18-24 months corrected age (CA), defined as a Bayley-III motor, language or cognitive composite score ≤69, or death before discharge while the secondary outcome was SNDI alone. We used mixed-effects regression models to evaluate the relationship between mean daily IHE rate per postnatal week of life for the first 12 weeks and the outcomes, and logistic regression models to assess the association between outcomes and summary measures of hypoxic burden for the entire NICU hospitalization.

RESULTS

The mortality rate was 7 % (18/249) during NICU hospitalization. Of 249 infants born during this time period, IHE and neurodevelopmental outcome data were fully available for 65 infants (mean GA 26 ± 1.4 weeks, mean birth weight (BW) 738 ± 199 g. The outcome of SNDI alone occurred in 34 % (22/65) with a majority demonstrating motor or language delay on the Bayley-III. Although mean daily IHE rate/week was not associated with SNDI or death, total IHE duration was associated with increased odds of SNDI (OR (95 % CI) 1.03 (1.01, 1.05), p = 0.008) in models adjusted for GA.

CONCLUSIONS

In a cohort of extremely premature infants 23-27 weeks GA, each hour of total IHE duration (SpO2 ≤ 80 %) was associated with a 2.7 % (0.7 %, 4.8 %) increase in the odds of SNDI at 18-24 months CA.

The Contribution of Commonly Diagnosed Genetic Disorders to Small for Gestational Age Birth and Subsequent Morbidity and Mortality in Preterm Infants

Objective

Preterm infants born small, vs. appropriate for gestational age (SGA, AGA) are at greater risk for morbidity and mortality. The contribution of genetic disorders to preterm SGA birth, morbidity, and mortality is unknown. We sought to determine the association between genetic disorders and preterm SGA birth, and the association between genetic disorders and morbidity or mortality within preterm SGA infants. We hypothesized that genetic disorders were significantly associated with both.

Study Design

This was a retrospective multicenter cohort study of 409 339 infants, born 23-33 weeks' gestation between 2000 and 2020. The odds of preterm SGA (vs AGA) birth, and the odds of severe morbidity or mortality within SGA preterm infants were determined for infants with genetic disorders, after adjusting for known risk factors.

Results

Genetic disorders were present in 3.0 and 1.3% of SGA and AGA preterm infants respectively; genetic disorders conferred an aOR (95% CI) of 2.06 (1.92, 2.21) of SGA birth. Genetic disorders were present in 4.3 of preterm SGA infants with morbidity or mortality and 2.1% of preterm SGA infants that did not experience morbidity or mortality. Genetic disorders conferred an aOR (95% CI) of 2.12 (2.66, 3.08) of morbidity or mortality.

Conclusions

Genetic disorders are strongly associated with preterm SGA birth, morbidity, and mortality. Clinicians should consider genetic testing of preterm SGA infants, particularly in the setting of other comorbidities or anomalies. Prospective, genomic research is needed to clarify the contribution of genetic disorders to disease in this population.

Case report: Pneumatosis in a neonate with thrombocytopenia absent radius syndrome

BACKGROUND

Thrombocytopenia absent radius (TAR) syndrome is a rare disease with an estimated prevalence of one in 200,000 live births. TAR is associated with cardiac and renal anomalies as well as gastrointestinal problems such as CMPA. Typically neonates with CMPA present with mild intolerance, with few reports in the literature of more severe intolerance resulting in pneumatosis. We present a case of a male infant with thrombocytopenia absent radius (TAR) syndrome who developed gastric and colonic pneumatosis intestinalis.

CASE DESCRIPTION

An eight-day-old male infant born at 36 weeks gestation with a diagnosis of TAR, presented with bright red blood in his stool. At this time he was on full formula feeds. Given continued bright red blood within his stool, an abdominal radiograph was obtained which was consistent with colonic and gastric pneumatosis. A complete blood count (CBC) was notable for worsening thrombocytopenia, anemia and eosinophilia. Once enteral feeds were held there was rapid resolution of the radiographic findings and resolution of his bloody stool. He was ultimately diagnosed with a cow's milk protein allergy (CMPA).

CONCLUSION

Though there are reports of CMPA in patients with TAR, the severity of this patient's presentation with both colonic and gastric pneumatosis is unique. Without the knowledge of the association of CMPA with TAR, this case could have been misdiagnosed and led to reintroduction of cow's milk containing formula, resulting in further complications. This case highlights the importance of a timely diagnosis and severity of CMPA in this population.

Intracranial ultrasound abnormalities and mortality in preterm infants with and without fetal growth restriction stratified by fetal Doppler study results

OBJECTIVE

To evaluate whether fetal growth restriction (FGR) with or without abnormal Dopplers is associated with intracranial abnormalities and death in premature infants.

STUDY DESIGN

Premature infants with and without FGR born between 2016 and 2019 were included. Primary outcome was death, severe intraventricular hemorrhage (IVH) or periventricular leukomalacia (PVL). Groups were compared using standard bivariate testing and multivariable regression.

RESULTS

Among 168 FGR and 560 non-FGR infants, FGR infants with abnormal Dopplers had an increased incidence of death, severe IVH or PVL compared to non-FGR infants (13% (16/123) vs. 7% (41/560); p = 0.03) while FGR infants with normal Dopplers had a nonsignificant decrease. In a logistic regression model, FGR with abnormal Dopplers was associated with more than three times higher odds of death, severe IVH or PVL (OR 3.2, 95% CI 1.54,6.49; p < 0.001).

CONCLUSIONS

Growth-restricted infants with abnormal Dopplers had an increased risk of death, intracranial abnormalities, and prematurity-related morbidities.

Double Jeopardy: Prematurity and Congenital Heart Disease-What's Known and Why It's Important

This article is based on a composite of talks presented during the Double Jeopardy: Prematurity and Congenital Heart Disease Plenary Session at NeoHeart 2020, a global virtual conference.Prematurity and low weight remain significant risk factors for mortality after neonatal cardiac surgery despite a steady increase in survival. Newer and lower weight thresholds for operability are constantly generated as surgeons gather proficiency, technical mastery, and experience in performing complex procedures on extremely small infants. The relationship between birth weight and survival after cardiac surgery is nonlinear with 2 kilograms (kg) being an inflection point below which marked decline in survival occurs.The prevalence of congenital heart disease (CHD) in premature infants is more than twice that in term born infants. Increased risk of preterm birth in infants with CHD is most commonly due to spontaneous preterm birth and remains poorly understood.Advances in Neonatal-Perinatal medicine have led to a marked improvement in survival of neonates born prematurely over the last several decades. However, the risk of severe morbidities including retinopathy of prematurity, intraventricular hemorrhage, bronchopulmonary dysplasia and necrotizing enterocolitis remains significant in extremely low birth weight infants. Premature infants with CHD are at a greater risk of prematurity related morbidities than premature infants without CHD. Interventions that have been successful in decreasing the risk of these morbidities are addressed.

Survival and Developmental Outcomes of Neonates Treated with Extracorporeal Membrane Oxygenation: A 10-Year Single-Center Experience

OBJECTIVE

To evaluate the associations between the primary indication for extracorporeal membrane oxygenation (ECMO) in neonates and neurodevelopmental outcomes at 12 and 24 months of age.

STUDY DESIGN

This is a retrospective cohort study of neonates treated with ECMO between January 2006 and January 2016 in the Children's Hospital of Philadelphia newborn/infant intensive care unit. Primary indication for ECMO was classified as medical (eg, meconium aspiration syndrome) or surgical (eg, congenital diaphragmatic hernia). Primary study endpoints were assessed with the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III). Groups were compared with standard bivariate testing and multivariable regression.

RESULTS

A total of 191 neonates met the study's inclusion criteria, including 96 with a medical indication and 95 with a surgical indication. Survival to discharge was 71%, with significantly higher survival in the medical group (82% vs 60%; P = .001). Survivors had high rates of developmental therapies and neurosensory abnormalities. Developmental outcomes were available for 66% at 12 months and 70% at 24 months. Average performance on the Bayley-III was significantly below expected population normative values. Surgical patients had modestly lower the Bayley-III scores over time; most notably, 15% of medical infants and 49% of surgical infants had motor delay at 24 months (P = .03).

CONCLUSIONS

In this single-center cohort, surgical patients had lower survival rates and higher incidence of motor delays. Strategies to reduce barriers to follow-up and improve rates of postdischarge developmental surveillance and intervention in this high-risk population are needed.

Management of transient central diabetes insipidus with intravenous desmopressin in a premature infant with gastroschisis and septo-optic dysplasia: A case report

Central diabetes insipidus (CDI) may occur in the setting of intracranial abnormalities that affect the hypothalamus-pituitary system. It occurs rarely in neonates, especially in the premature population, and represents a challenging disease process to treat pharmacologically. Little is known regarding the treatment options in premature infants, including dose and route of administration of intravenous desmopressin (DDAVP). We present a case of a late premature male infant with gastroschisis and septo-optic dysplasia who developed transient CDI. He was treated with intravenous DDAVP but required frequent laboratory monitoring and a multidisciplinary approach, and ultimately his CDI resolved. Although there are minimal guidelines regarding the appropriate formulation and dosage of DDAVP for management of CDI in infants, we initiated the lowest dose available and titrated the medication based on close monitoring of urine output and serum sodium levels in order to successfully treat his transient CDI.

Care of the COVID-19 exposed complex newborn infant

As we confront COVID-19, the global public health emergency of our times, new knowledge is emerging that, combined with information from prior epidemics, can provide insights on how to manage this threat in specific patient populations. Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS), both caused by coronaviruses, caused serious respiratory illness in pregnant women that resulted in adverse perinatal outcomes. Thus far, COVID-19 appears to follow a mild course in the vast majority of pregnant women. A significant proportion of pregnant women appear to be asymptomatic carriers of SARS-CoV-2. However, there is limited information on how COVID-19 impacts the fetus and whether vertical transmission occurs. While these knowledge gaps are addressed, it is important to recognize the highly efficient transmission characteristics of SARS-C0V-2 and its potential for causing serious disease in vulnerable individuals, including health care workers. This review provides perspectives from a single center in New York City, the epicenter of the pandemic within the United States. It offers an overview of the preparations required for deliveries of newborns of mothers with COVID-19 and the management of neonates with particular emphasis on those born with complex issues.

Neonates With Complex Cardiac Malformation and Congenital Diaphragmatic Hernia Born to SARS-CoV-2 Positive Women-A Single Center Experience

BACKGROUND

Our understanding of the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on pregnancies and perinatal outcomes is limited. The clinical course of neonates born to women who acquired coronavirus disease 2019 (COVID-19) during their pregnancy has been previously described. However, the course of neonates born with complex congenital malformations during the COVID-19 pandemic is not known.

METHODS

We report a case series of seven neonates with congenital heart and lung malformations born to women who tested positive for SARS-CoV-2 during their pregnancy at a single academic medical center in New York City.

RESULTS

Six infants had congenital heart disease and one was diagnosed with congenital diaphragmatic hernia. In all seven infants, the clinical course was as expected for the congenital lesion. None of the seven exhibited symptoms generally associated with COVID-19. None of the infants in our case series tested positive by nasopharyngeal test for SARS-CoV-2 at 24 hours of life and at multiple points during their hospital course.

CONCLUSIONS

In this case series, maternal infection with SARS-CoV-2 during pregnancy did not result in adverse outcomes in neonates with complex heart or lung malformations. Neither vertical nor horizontal transmission of SARS-CoV-2 was noted.

Human Herpesvirus-6 Meningitis in a Premature Infant with Fevers: A Case and Literature Review

Human herpesvirus-6 (HHV-6) is a common virus that can cause nearly universal infection in infancy and early childhood. It typically manifests as an acute febrile illness. We describe a case of a premature infant with congenital hydrocephalus secondary to aqueductal stenosis with a ventriculoperitoneal shunt in place who developed intermittent fevers while she was admitted to the neonatal intensive care unit. She was ultimately diagnosed with acute HHV-6 meningitis. In addition to this report, we present a literature review regarding this virus’s potential modes of transmission and forms of clinical presentation in the neonatal period.

Brain natriuretic peptide and insulin resistance in older adults

AIMS

Higher levels of brain natriuretic peptide (BNP) have been associated with a decreased risk of diabetes in adults, but whether BNP is related to insulin resistance in older adults has not been established.

METHODS

N-terminal of the pro hormone brain natriuretic peptide (NT-pro BNP) was measured among Cardiovascular Health Study participants at the 1989-1990, 1992-1993 and 1996-1997 examinations. We calculated measures of insulin resistance [homeostatic model assessment of insulin resistance (HOMA-IR), quantitative insulin sensitivity check index (QUICKI), Gutt index, Matsuda index] from fasting and 2-h concentrations of glucose and insulin among 3318 individuals with at least one measure of NT-proBNP and free of heart failure, coronary heart disease and chronic kidney disease, and not taking diabetes medication. We used generalized estimating equations to assess the cross-sectional association of NT-proBNP with measures of insulin resistance. Instrumental variable analysis with an allele score derived from nine genetic variants (single nucleotide polymorphisms) within or near the NPPA and NPPB loci was used to estimate an un-confounded association of NT-proBNP levels on insulin resistance.

RESULTS

Lower NT-proBNP levels were associated with higher insulin resistance even after adjustment for BMI, waist circumference and other risk factors (P < 0.001 for all four indices). Although the genetic score was strongly related to measured NT-proBNP levels amongst European Americans (F statistic = 71.08), we observed no association of genetically determined NT-proBNP with insulin resistance (P = 0.38; P = 0.01 for comparison with the association of measured levels of NT-proBNP).

CONCLUSIONS

In older adults, lower NT-proBNP is associated with higher insulin resistance, even after adjustment for traditional risk factors. Because related genetic variants were not associated with insulin resistance, the causal nature of this association will require future study.

HSV oropharyngeal shedding among HIV-infected children in Tanzania

Herpes simplex virus (HSV) oral shedding has not been studied among HIV-positive children in Africa. We sought to evaluate longitudinal oral HSV reactivation in HIV-positive and -negative children. Twenty HIV-positive antiretroviral-naive and 10 HIV-negative children aged 3-12 years in Tanzania were followed prospectively for 14 days. Oral swabs were collected daily and submitted for HSV DNA PCR analysis. Clinical data were collected via chart review and daily diaries. HSV DNA was detected in 10 (50%) of HIV-positive and 4 (40%) of HIV-negative children. Children who shed HSV had virus detected in a median of 21.4% of samples; shedding was intermittent. Median CD4 count among HIV-infected children was 667 cells/µL in those with positive HSV DNA and 886 cells/µL in those who were negative (p = 0.6). Of the HIV-positive children reporting prior sores, five (83%) had positive HSV swabs, whereas the one HIV-negative child with prior sores did not have a PCR-positive swab. HSV is detected frequently in children with and without HIV. HIV-infected children reporting oral sores have a high rate of HSV detection. Given the proven strong interactions between HIV and HSV, further study of co-infection with these viruses is warranted in children.

Plasma cytokine concentrations and quality of life in patients with non-small cell lung cancer in a phase II trial of first-line treatment with carboplatin-paclitaxel and/or vandetanib

9596

Background: A randomized phase II trial (JCO 26:5407–15, 2008) compared carboplatin-paclitaxel (CP) with vandetanib (VEGFR-EGFR inhibitor) monotherapy (V) and V plus CP (VCP) 1st-line for advanced NSCLC (N=181). PFS was superior for VCP vs CP (HR 0.76). We performed analyses of quality of life (QOL) and its correlations with plasma concentrations of cytokines and angiogenic factors (CAF) among the participants in this trial. Methods: QOL was serially measured by Functional Assessment of Cancer Therapy-Lung (FACT-L) and Trial Outcome Index (TOI) scores. Concentrations of 35 plasma CAFs were measured at baseline and multiple timepoints during treatment with multiplexed bead suspension arrays and ELISAs. We performed exploratory analyses for the following associations: (1) QOL with plasma CAF levels at baseline; (2) changes in QOL with changes in plasma CAF levels. Spearman correlation coefficient, log-rank test and mixed linear models were applied in the analyses. P-value < 0.05 was considered significant. Results: Baseline QOL and plasma samples were both available for 120 patients. Lower baseline FACT-L scores (inferior QOL) were associated with higher pre-treatment plasma levels of INF-γ, IL-1RA, IL-6, IL-12, IL-15, TNF-α, RANTES, MIG, MIP-1β, MMP-9, bFGF, VEGF and sVEGFR-2 (all P<0.05). Lower baseline TOI scores (inferior QOL) were also associated with higher pre-treatment plasma levels of multiple CAFs, including GCSF, HGF, INF-α, INF-γ, IL-2, IL-6, IL-8, IL-12, IL-15, TNF-α, bFGF, sVEGFR-2 and VEGF (all P<0.05). Among all patients, decreasing TOI scores post cycle 2 (HR=2.57 [1.28,5.17], P=0.008) and cycle 4 (HR=2.58 [1.01,6.56], P=0.049) were associated with increased progression risk. Trends for FACT-L were similar, but did not reach statistical significance. Rises in GCSF, HGF, IL-2, IL-8, IL-15, MCP-1, MIP-1β, and VEGF from baseline to post cycle 2 were associated with decreased FACT-L and/or TOI scores (all P<0.05). Conclusions: High plasma concentrations of multiple CAFs pre-treatment in patients with NSCLC correlated with inferior QOL, and rises in these factors during treatment were associated with worsening QOL. This work was funded in part by grant from ACS (FK).

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Endothelial inflammation induced by excess glucose is associated with cytosolic glucose 6-phosphate but not increased mitochondrial respiration

AIMS/HYPOTHESIS

Exposure of endothelial cells to high glucose levels suppresses responses to insulin, including induction of endothelial nitric oxide synthase activity, through pro-inflammatory signalling via the inhibitor of nuclear factor kappaB (IkappaB)alpha-nuclear factor kappaB (NF-kappaB) pathway. In the current study, we aimed to identify metabolic responses to glucose excess that mediate endothelial cell inflammation and insulin resistance. Since endothelial cells decrease their oxygen consumption rate (OCR) in response to glucose, we hypothesised that increased mitochondrial function would not mediate these cells' response to excess substrate.

METHODS

The effects of glycolytic and mitochondrial fuels on metabolic intermediates and end-products of glycolytic and oxidative metabolism, including glucose 6-phosphate (G6P), lactate, CO(2), NAD(P)H and OCR, were measured in cultured human microvascular endothelial cells and correlated with IkappaBalpha phosphorylation.

RESULTS

In response to increases in glucose concentration from low to physiological levels (0-5 mmol/l), production of G6P, lactate, NAD(P)H and CO(2) each increased as expected, while OCR was sharply reduced. IkappaBalpha activation was detected at glucose concentrations >5 mmol/l, which was associated with parallel increases of G6P levels, whereas downstream metabolic pathways were insensitive to excess substrate.

CONCLUSIONS/INTERPRETATION

Phosphorylation of IkappaBalpha by excess glucose correlates with increased levels of the glycolytic intermediate G6P, but not with lactate generation or OCR, which are inhibited well below saturation levels at physiological glucose concentrations. These findings suggest that oxidative stress due to increased mitochondrial respiration is unlikely to mediate endothelial inflammation induced by excess glucose and suggests instead the involvement of G6P accumulation in the adverse effects of hyperglycaemia on endothelial cells.

Bilateral volume reduction of the superior temporal areas in Landau-Kleffner syndrome

No specific anatomic abnormalities have been detected in typical Landau-Kleffner syndrome (LKS), an acquired epileptic aphasia with language regression in children. In four children with typical LKS without obvious anatomic abnormalities, the authors performed MRI volumetric analysis of various neocortical regions and subcortical substructures. Volume reduction was detected in bilateral superior temporal areas (26 to 51%), specifically in planum temporale (25 to 63%) and superior temporal gyrus (25 to 57%), where receptive language is localized.

Orthodontic treatment of a case of Becker muscular dystrophy

Becker muscular dystrophy, similar to Duchenne muscular dystrophy, is a X-chromosomal linked anomaly characterized by progressive muscle wasting and weakness. Duchenne-type is known to have severe openbite with a steep mandibular plane, but there are no studies that describe the occlusal and skeletal patterns of the Becker-type. Here, we report the orthodontic treatment of a Becker muscular dystrophy patient. In the correction of his severe skeletal open bite general anesthesia or orthognathic surgery was not an option. Multiloop edgewise archwires were employed for orthodontic treatment. After 3 years and 8 months the open bite was corrected. During the retention period contact between the anterior teeth was maintained 8 months after active treatment despite a marked relapse tendency.

Effects of pharmacologic androgen treatment duration on glucocorticoid receptor alpha immunoreactivity of lumbosacral motor neurons in the male rat

It has previously been suggested that anabolic-androgenic steroids may affect neuromuscular function through their potential action as glucocorticoid receptor antagonists. Alternatively, androgens may regulate the sensitivity of neuromuscular systems to glucocorticoids by modulating GR levels. The purpose of this study was to determine the effects of chronic pharmacologic testosterone treatment of gonadally intact male rats on glucocorticoid receptor alpha immunoreactivity (GRalpha-IR) of motor neurons in the lumbosacral spinal cord. Circulating testosterone levels were chronically increased by subcutaneous Silastic capsules containing crystalline testosterone propionate (TP) for 7, 14, and 28 days. Age-matched sham-operated gonadally intact males served as controls. Relative cytoplasmic and nuclear GRalpha-IR of motor neurons located in the lateral motor column of spinal cord segments L(3) and L(4) (L(Lat); innervating rat hindlimb muscles) and the spinal nucleus of the bulbocavernosus (SNB; innervating the external anal sphincter, bulbocavernosus and levator ani muscles) was measured densitometrically. TP treatment duration had a significant impact on the mean GRalpha levels of both cellular compartments regardless of motor column (two-way ANOVA, P<0.001). The mean nuclear GRalpha-IR of lumbar motor neurons was significantly reduced after 7 days (OD: 0.239+/-0.013 S.E.M.; P<0.016) and 14 days (OD: 0.196+/-0.013; P<0.001) from the GRalpha-IR levels observed among the control group (OD: 0.296+/-0.012) by 20 and 40%, respectively. Interestingly, nuclear GRalpha-IR levels were similar to control levels after 28 days of TP treatment (OD: 0.307+/-0.010). Treatment-dependent changes in cytoplasmic GRalpha-IR paralleled the observed changes in nuclear GRalpha-IR. These data suggest that pharmacologic testosterone treatment effects on motor neuron gene expression may be mediated by testosterone-induced temporal fluctuations of GRalpha-dependent gene regulation.

Crural ligation surgery for the young male with venogenic erectile dysfunction: technique

Isolated crural venous leak is an uncommon cause of erectile dysfunction. Recent data have suggested that ligation of the crura in men with this condition may result in significant improvement in erectile function. This report outlines the criteria for patient selection and the technique we use to accomplish crural ligation.

Memory deficits among children with craniopharyngiomas

OBJECTIVE

To describe neuropsychological functioning (with a specific focus on cognition and memory) after surgical treatment of craniopharyngiomas.

METHODS

Sixteen patients who were between 6 and 15 years of age at the time of surgery comprised the sample. Each child had been treated for a craniopharyngioma with surgery only, on Dana-Farber Cancer Institute Protocol 92-077.

RESULTS

The overall level of cognitive functioning was well within the average range, with both language and visuospatial functioning being generally intact; however, specific memory problems, in both the language and visuospatial domains, were evident.

CONCLUSION

Although general cognitive functioning was intact after the surgical treatment of craniopharyngiomas, difficulties in the retrieval of learned information were observed. Neuropsychological assessments, with a focus on memory recall, should be a component of the medical management plan for each child.

TNF-alpha inhibits flow and insulin signaling leading to NO production in aortic endothelial cells

Endothelial cells release nitric oxide (NO) acutely in response to increased "flow" or fluid shear stress (FSS), and the increase in NO production is correlated with enhanced phosphorylation and activation of endothelial nitric oxide synthase (eNOS). Both vascular endothelial growth factor and FSS activate endothelial protein kinase B (PKB) by way of incompletely understood pathway(s), and, in turn, PKB phosphorylates eNOS at Ser-1179, causing its activation. In this study, we found that either FSS or insulin stimulated insulin receptor substrate-1 (IRS-1) tyrosine and serine phosphorylation and increased IRS-1-associated phosphatidylinositol 3-kinase activity, phosphorylation of PKB Ser-473, phosphorylation of eNOS Ser-1179, and NO production. Brief pretreatment of bovine aortic endothelial cells with tumor necrosis factor-alpha (TNF-alpha) inhibited the above described FSS- or insulin-stimulated protein phosphorylation events and almost totally inhibited FSS- or insulin-stimulated NO production. These data indicate that FSS and insulin regulate eNOS phosphorylation and NO production by overlapping mechanisms. This study suggests one potential mechanism for the development of endothelial dysfunction in disease states with alterations in insulin regulation and increased TNF-alpha levels.

Hyperthermia induces heat-shock protein expression, reduces pancreatic injury, and improves survival in necrotizing pancreatitis

Heat-shock proteins (HSPs) function in the cellular response to injury. Increased expression of these proteins was first described in response to hyperthermia, although their production may be prompted by a variety of metabolic insults. HSPs protect cellular proteins from degradation. The self-limited pancreatitis induced by hyperstimulation with supramaximal doses of cerulein is accompanied by increased HSP expression. It may be that HSPs serve a protective function in pancreatitis. We hypothesized that hyperthermia-induced production of HSP-70 would improve survival in a lethal murine model of necrotizing pancreatitis. Necrotizing pancreatitis was induced in two groups of 30 female Swiss Webster mice by feeding them a choline-deficient diet supplemented with 0.5 g% ethionine (CDE) for 72 hours. Immediately before initiation of the CDE diet, the core body temperatures of the mice in the experimental group were elevated to 42 degrees C for 12.5 minutes. Twenty mice from each group were killed after 24 hours. Pancreata were harvested, and pancreatic proteins were extracted from half of the pancreata. HSP-70 was assessed according to a standard Western blotting protocol. The remaining pancreata were used to make histologic comparisons. Serum interleukin 6 and tumor necrosis factor-alpha were determined by enzyme-linked immunosorbent assay (ELISA). Survival was determined by observation of the remaining mice. HSP-70 was expressed in pancreatic protein from all mice exposed to hypothermia but in none of the mice subjected to the CDE diet alone. Mortality was significantly reduced in mice pretreated with hyperthermia compared with control mice (p < 0.05). Survival in the hyperthermia group was 80%, whereas in the control group it was 30%. Hyperthermia resulted in expression of pancreatic HSP-70 in mice. Hyperthermia also reduced mortality in this lethal murine model of necrotizing pancreatitis. It is plausible that a causal relationship exists between HSP-70 production and improved survival in this model.

Adhesion to fibronectin enhances MKP-1 activation in human endothelial cells

Integrin-mediated substrate adhesion of endothelial cells leads to intracellular signaling, including the activation of ERK 1/2 (extracellular regulated kinases 1 and 2), members of the mitogen-activated protein kinase (MAPK) family. MKP-1 is a dual-specificity protein phosphatase that may play an important role in regulating MAPK activity through dephosphorylation of threonine and tyrosine. Adhesion of human umbilical vein endothelial cells to fibronectin increased MKP-1 protein and mRNA levels, which reached a maximum at 60 min, while MAPK activity was maximal at 30 min. The MEK inhibitor PD98059 blocked activation of MAPK as well as the induction of MKP-1 during adhesion. The transcription inhibitor actinomycin D blocked MKP-1 induction and produced prolonged MAPK activation during adhesion. In contrast, endothelial adhesion to poly-L-lysine did not alter MAPK activity or MKP-1 levels. These findings demonstrate that integrin-mediated adhesion of endothelial cells to fibronectin results in transcriptional activation of MKP-1 through a MAPK-dependent mechanism. Regulation of MKP-1 by MAPK likely represents an important negative-feedback mechanism.

B-cell leukemia protein-2 and peptide YY chemotherapy resistance in colon cancer

BACKGROUND

Inhibition of apoptosis may allow cells with drug-induced damage to escape programmed cell death. The bcl-2 protein inhibits apoptosis and bcl-2 overexpression has been associated with drug resistance. It is our hypothesis that higher levels of bcl-2 expression will be seen in colon cancer cells resistant to PYY treatment.

METHODS

Caco2 and HCT116 colon cancer cells were treated with 2 microM PYY for 24 hours. Protein was extracted from cells surviving PYY treatment; bcl-2 expression was measured by enzyme-linked immunosorbent assay (ELISA) and confirmed by Western blotting.

RESULTS

Caco2 and HCT116 cells surviving PYY treatment demonstrated increased bcl-2 from 20.54+/-2.7 to 28.63+/-2.20 units/mL (P <0.05) and 21.98+/-1.28 to 29.32*+/-2.26 units/mL, respectively.

CONCLUSIONS

Increased expression of bcl-2 is seen in a population of colon cancer cells resistant to PYY. Hence, bcl-2 may protect neoplastic cells from apoptosis; its levels may be useful in predicting chemotherapy response and in selecting appropriate drug regimens.

Identification of flow-dependent endothelial nitric-oxide synthase phosphorylation sites by mass spectrometry and regulation of phosphorylation and nitric oxide production by the phosphatidylinositol 3-kinase inhibitor LY294002

Endothelial cells release nitric oxide (NO) acutely in response to increased laminar fluid shear stress, and the increase is correlated with enhanced phosphorylation of endothelial nitric-oxide synthase (eNOS). Phosphoamino acid analysis of eNOS from bovine aortic endothelial cells labeled with [(32)P]orthophosphate demonstrated that only phosphoserine was present in eNOS under both static and flow conditions. Fluid shear stress induced phosphate incorporation into two specific eNOS tryptic peptides as early as 30 s after initiation of flow. The flow-induced tryptic phosphopeptides were enriched, separated by capillary electrophoresis with intermittent voltage drops, also known as "peak parking," and analyzed by collision-induced dissociation in a tandem mass spectrometer. Two phosphopeptide sequences determined by tandem mass spectrometry, TQpSFSLQER and KLQTRPpSPGPPPAEQLLSQAR, were confirmed as the two flow-dependent phosphopeptides by co-migration with synthetic phosphopeptides. Because the sequence (RIR)TQpSFSLQER contains a consensus substrate site for protein kinase B (PKB or Akt), we demonstrated that LY294002, an inhibitor of the upstream activator of PKB, phosphatidylinositol 3-kinase, inhibited flow-induced eNOS phosphorylation by 97% and NO production by 68%. Finally, PKB phosphorylated eNOS in vitro at the same site phosphorylated in the cell and increased eNOS enzymatic activity by 15-20-fold.

Cloning and characterization of adeno-associated virus type 5

Adeno-associated virus type 5 (AAV5) is distinct from other dependovirus serotypes based on DNA hybridization and serological data. To better understand the biology of AAV5, we have cloned and sequenced its genome and generated recombinant AAV5 particles. The single-stranded DNA genome is similar in length and genetic organization to that of AAV2. The rep gene of AAV5 is 67% homologous to AAV2, with the majority of the changes occurring in the carboxyl and amino termini. This homology is much less than that observed with other reported AAV serotypes. The inverted terminal repeats (ITRs) are also unique compared to those of the other AAV serotypes. While the characteristic AAV hairpin structure and the Rep DNA binding site are retained, the consensus terminal resolution site is absent. These differences in the Rep proteins and the ITRs result in a lack of cross-complementation between AAV2 and AAV5 as measured by the production of recombinant AAV particles. Alignment of the cap open reading frame with that of the other AAV serotypes identifies both conserved and variable regions which could affect tissue tropism and particle stability. Comparison of transduction efficiencies in a variety of cells lines and a lack of inhibition by soluble heparin indicate that AAV5 may utilize a distinct mechanism of uptake compared to AAV2.

Interleukin-10 inhibits inducible nitric oxide synthase in an animal model of necrotizing enterocolitis

BACKGROUND

Nitric oxide (NO) and its role in surgical inflammation are well documented; demonstrating the role of NO in necrotizing enterocolitis (NEC) and ways in which it may be suppressed may provide avenues for immune modulation in the treatment of NEC.

AIMS

We sought to demonstrate an increase in inducible nitric oxide synthase (iNOS) mRNA and nitric oxide in an experimental model of necrotizing enterocolitis. In addition, we hypothesized that interleukin-10 (IL-10) would attenuate this response.

METHODS

Newborn rats were treated with 25 microliters intraperitoneal IL-10 or vehicle prior to laparotomy, 1 h superior mesenteric artery (SMA) occlusion, 50 micrograms/kg intraluminal platelet activating factor administration, and SMA reperfusion. iNOS mRNA and nitric oxide levels were measured in the liver, small bowel, and serum and compared using Student's t-test.

RESULTS

Small bowel iNOS mRNA increased after NEC induction from 0.058 +/- 0.02 to 0.144 +/- 0.05 relative intensity units (RIU) at 2 h (p < 0.01) and from 0 to 0.09 +/- 0.02 RIU at 6 h (p < 0.03). Liver mRNA increased from 0.026 +/- 0.002 to 0.485 +/- 0.09 RIU (p < 0.002) and from 0 to 0.069 +/- 0.02 RIU (p < 0.0001) at 2 and 6 h, respectively. Serum nitric oxide increased in NEC induced animals at 2 h from 28.04 +/- 10.5 to 45.18 +/- 6.8 microM (p < 0.001). IL-10 suppressed iNOS mRNA and nitric oxide expression at 2 h in small bowel, liver, and serum by 60%, 89%, and 11%, respectively.

CONCLUSIONS

IL-10 decreases iNOS mRNA response in experimental NEC. This down-regulation may be an avenue for anti-inflammatory intervention in NEC.

A conserved role for L1 as a transmembrane link between neuronal adhesion and membrane cytoskeleton assembly

The L1-family of cell adhesion molecules is involved in many important aspects of nervous system development. Mutations in the human L1-CAM gene cause a complicated array of neurological phenotypes; however, the molecular basis of these effects cannot be explained by a simple loss of adhesive function. Human L1-CAM and its Drosophila homolog neuroglian are rather divergent in sequence, with the highest degree of amino acid sequence conservation between segments of their cytoplasmic domains. In an attempt to elucidate the fundamental functions shared between these distantly related members of the L1-family, we demonstrate here that the extracellular domains of mammalian L1-CAMs and Drosophila neuroglian are both able to induce the aggregation of transfected Drosophila S2 cells in vitro. To a limited degree they even interact with each other in cell adhesion and neurite outgrowth assays. The cytoplasmic domains of human L1-CAM and neuroglian are both able to interact with the Drosophila homolog of the cytoskeletal linker protein ankyrin. Moreover the recruitment of ankyrin to cell-cell contacts is completely dependent on L1-mediated cell adhesion. These findings support a model of L1 function in which the phenotypes of human L1-CAM mutations results from a disruption of the link between the extracellular environment and the neuronal cytoskeleton.

Characterization of vitelline membrane outer layer protein I, VMO-I: amino acid sequence and structural stability

Vitelline membrane outer layer protein I (VMO-I) tightly bound to ovomucin fibrils of hen's egg yolk membrane was characterized in terms of its amino acid sequence and structural stability. The deduced sequence of VMO-I using the conventional sequencing method is: RTREYTSVITVPNGGHWGKWGIRQFCHSGYANGFALKVEPSQFGRDDTALNGIRLRCLD- GSVIESLVGKWGTWTSFLVCPTGYLVSFSLRSEKSQGGGDDTAANNIQFRCSDEAVLVGD- DLSWGRFGPWSKRCKICGLQTKVESPQGLRDDTALNNVRFFCCK. Thus, VMO-I is composed of 163 amino acid residues with a calculated molecular weight of 17,979. The sequence confirms the cDNA sequence of VMO-I we recently determined and does not show any significant similarity to proteins compiled in the NBRF database. Two of the four disulfide bonds found in VMO-I were estimated to lie between Cys26 and Cys57 and between Cys79 and Cys110. The sequence analyses show that VMO-I contains three 53-residue internal repeats that contain distinctive regions of turns flanked by beta-sheets consistent with the recent finding that the molecule contains a new beta-fold motif, the beta-prism. The molecular characteristics of VMO-I in solution were examined by CD spectroscopy in the far and near ultraviolet regions, NMR spectroscopy, and high sensitive differential scanning calorimetry (DSC). CD spectra in the far UV region at room temperature were similar to that assigned to a random coil, while in the near UV region, small positive peaks were observed. The ellipticity in both regions decreased on raising the temperature. Proton NMR experiments showed the native structure unfolds to unordered conformations at 70 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of a biosensor based on surface plasmon resonance and biotinyl glycans for analysis of sugar binding specificities of lectins

We have developed a new method for analysis of the interaction between lectins and biotin-derivatized oligosaccharides involving a biosensor based on surface plasmon resonance. Complex type asialo-bi-, tri-, and tetra-antennary oligosaccharides were quantitatively converted into their biotin derivatives by incubating them with 6-(D-biotinyl)-aminohexanoyl hydrazide. This method was also applicable to sialyl sugar chains without any removal of sialic acid residues. The reaction mixture could be directly injected onto the streptavidin pre-immobilized surface of a sensor chip without any purification because of its fairly low reagent/carbohydrate molar ratio. The amounts of sugar chains required for interaction analysis by this method were as low as 1 pmol. The binding specificities of Sambucus sieboldiana lectin, Maackia amurensis lectin, Ricinus communis agglutinin-120 (RCA120), and concanavalin A could be rapidly determined qualitatively by this method. Furthermore, kinetic analysis of the interaction between RCA120, and complex type asialo-bi-, tri-, and tetra-antennary oligosaccharides revealed that both the association rate constant and the dissociation rate constant (kdiss) decreased with increasing numbers of terminal galactosyl residues. Because the tendency observed for kdiss paralleled the elution order of these oligosaccharides on RCA120 immobilized affinity chromatography, kiss might hold the key to determination of the elution order on affinity chromatography.

Gut ischemia induces bone marrow failure and increases risk of infection

Hemorrhagic shock leads to bone marrow (BM) failure and renders the host susceptible to infection. We hypothesized that splanchnic hypoperfusion may play a mechanistic role in this process. BM was harvested from normal rats and, on Postprocedure Days 1 and 3, from rats that had undergone laparotomy (LAP) or gut ischemia/reperfusion (I/R; 45 min superior mesentery artery occlusion). Granulocyte-macrophage colony-forming unit (CFU-GM) proliferation, a measure of BM myeloid progenitors, was quantitated using a standard soft agar culture technique. On Postprocedure Days 1 and 3, BM proliferation of CFU-GM was depressed in gut I/R rats, compared to control and LAP animals (P < 0.05). Next, six rats were subjected to I/R, LAP, ANEST (anesthesia control), or no treatment (NL, normal control); 1 day later, 3.5 x 10(7) Staphylococcus aureus, suspended in 0.25 ml of saline, were injected subcutaneously in four sites on the back of each animal. Five days later, the NL rats had developed 23 abscesses, ANEST 23, and LAP 22, while the gut I/R rats had 24. The abscesses were excised, weighed, and measured. The weight and size of abscesses were greater in the gut I/R animals (P < 0.05). In summary, gut I/R depressed BM proliferation and rendered animals susceptible to infection in a manner similar to that observed following hemorrhagic shock. These data suggest that splanchnic hypoperfusion, a common sequela of hemorrhagic shock, may play a mechanistic role in BM failure and infection after hemorrhage.

Kinetic measurement of the interaction between an oligosaccharide and lectins by a biosensor based on surface plasmon resonance

Kinetic measurements of the interaction between an oligosaccharide and various lectins were performed using a biosensor based on surface plasmon resonance (SPR). A glycopeptide, prepared from asialofetuin and having a nearly homogeneous N-linked sugar chain, was immobilized on the surface of a sensor chip via the amino groups of its peptide moiety. The interactions of this bound glycopeptide with six lectins [Sambucus sieboldiana lectin, Maackia amurensis lectin, Aleuria aurantia lectin, Ricinus communis agglutinin-120 (RCA120), Datura stramonium lectin (DSA) and Phaseolus vulgaris leukoagglutinating lectin] were monitored in real-time with the change in the SPR response. Of these lectins, only RCA120 and DSA showed an increase in the SPR response, indicating that these two lectins bound specifically to the immobilized glycopeptide. The other lectins did not show any significant changes in the SPR response. These results are in good agreement with the binding specificity previously demonstrated with affinity chromatography. The association-rate constant (kass) and the dissociation-rate constant (kdiss) for the glycopeptide-RCA120 interaction were 3.4 x 10(5) M-1 s-1 and 2.1 x 10(-3) s-1, respectively. The kass and kdiss determined for DSA were 5.7 x 10(5) M-1 s-1 and 1.3 x 10(-3) s-1, respectively. Furthermore, the relative binding molar ratio to the glycopeptide was three times higher for RCA120 than for DSA, suggesting that this sugar chain possesses three binding sites for RCA120 and one for DSA. These parameters are expected to provide useful information for defining the interaction between oligosaccharides and lectins.

Isolation of a novel protein from the outer layer of the vitelline membrane

The outer layer of the vitelline membrane from hen egg yolk consists of ovomucin, vitelline membrane outer layer protein I (VMOI) and lysozyme. Here we report the occurrence of a further basic protein (pI 11.5) in the outer layer, which was designated as vitelline membrane outer layer protein II (VMOII). It was dissociated from the outer layer in a 10% (w/v) NaCl solution and purified to homogeneity by ion-exchange chromatography. VMOII is a simple protein with a molecular mass of 6000 Da, as determined by sedimentation equilibrium analysis. The amino acid composition of VMOII was characterized by the absence of Met and high contents of cystine (half) (14%) and basic amino acids (6% Arg, 6% Lys and 3% His). Analysis of carboxymethylated VMOII indicated that all cysteine residues were involved in disulphide bonding, which appears to facilitate the binding of SDS to the protein. Sequence comparison of the N-terminal 20 residues revealed no identity with other known proteins. VMOII contained a small amount of alpha-helix and was quite resistant to heat denaturation.

The amino-terminal fragment of gelsolin is cross-linked to Cys-374 of actin in the EGTA-resistant actin-gelsolin complex

It has been shown that the EGTA-resistant actin, one of the two actin molecules associated to gelsolin, can be predominantly cross-linked to gelsolin by benzophenone-4-maleimide (BPM), a photoaffinity-labeling reagent, which was conjugated to Cys-374 of actin prior to cross-linking (Doi, Y., Banba, M. and Vertut-Doï, A. (1991) Biochemistry 30, 5769-5777). When a chymotryptic digest of gelsolin containing the amino-terminal 15-kDa fragment was mixed with BPM-actin (42 kDa) and irradiated for cross-linking, a band of 58 kDa appeared on SDS-PAGE which was shown to contain actin molecule by using fluorescently labeled actin. The amino-terminal sequence of the 58-kDa complex was identical to that of gelsolin, confirming that the amino-terminal segment (residues 1-133) of pig plasma gelsolin lies closely to Cys-374 of actin in the EGTA-resistant complex.

Absence of abundant binding sites for anesthetics in rabbit brain: an in vivo NMR study

Using magnetic resonance spectroscopy, the authors tested whether cerebral concentrations of inhaled anesthetics do not increase proportionately at inspired concentrations exceeding 3% 1) because anesthetics bind to and saturate specific sites in the brain or 2) because anesthetic-induced depression of ventilation limits the increase in alveolar anesthetic partial pressure. New Zealand White rabbits were anesthetized with methohexital, 70% nitrous oxide, and local infiltration of 1% lidocaine. Cerebral concentrations of anesthetic were determined from 19F spectra acquired with nuclear magnetic resonance (NMR). Inspired, end-tidal, and arterial anesthetic concentrations, and end-tidal and arterial partial pressure of carbon dioxide were measured. Blood/gas partition coefficients were determined and used to convert arterial anesthetic concentration to partial pressures. In seven spontaneously breathing animals, halothane (1%; n = 5) or isoflurane (0.8%; n = 2) was administered at a constant inspired concentration for 20 min; NMR spectra were acquired between 10 and 20 min. Thereafter, the inspired concentration was increased and the process repeated until apnea occurred. Two additional rabbits were anesthetized with isoflurane and studied similarly but with higher inspired concentrations during mechanical ventilation. In spontaneously breathing animals, ventilatory depression occurred, documented by marked increases in PaCO2, and cerebral concentrations of anesthetic did not increase proportionately at inspired concentrations exceeding 3%. In contrast to an absence of a correlation of inspired and cerebral concentrations during spontaneous ventilation, arterial and cerebral concentrations correlated linearly during both spontaneous and mechanical ventilation (R2 greater than 0.969). These results are consistent with depression of ventilation, rather than binding to specific cerebral sites as an explanation for the nonlinear relationship between cerebral and inspired anesthetic concentrations.

Stimulation of human peripheral blood polymorphonuclear cell iodination by PSK subfractions

A protein-bound polysaccharide, PSK, extracted from the mycelium of Coriolus versicolor (Fr.) Quel, stimulated the iodination (incorporation of radioactive iodine into an acid-insoluble fraction) of human peripheral blood polymorphonuclear cells (PMN), human promyelocytic leukemic HL-60 cells and human myeloblastic leukemic ML-1 cells. In contrast, PSK did not significantly increase the iodination of other cultured cell lines (U-937, THP-1, L-929, T98G, BALB 3T3). The PSK stimulation of iodination of both PMN and HL-60 cells depended on incubation time and temperature, and was significantly suppressed by the presence of myeloperoxidase inhibitors. Among various PSK subfractions, the highest molecular weight fraction (MW greater than 200 kD), or the fraction precipitated at pH 4.0-4.5, stimulated the iodination most. In contrast, natural and chemically modified glucans had little or no stimulation activity. The active PSK subfractions synergistically enhanced TNF stimulation of PMN iodination. The data suggest the presence of some unique components in PSK which directly stimulate the iodination of myeloperoxidase-positive cells.

Stability of brain intracellular lactate and 31P-metabolite levels at reduced intracellular pH during prolonged hypercapnia in rats

The tolerance of low intracellular pH (pHi) was examined in vivo in rats by imposing severe, prolonged respiratory acidosis. Rats were intubated and ventilated for 10 min with 20% CO2, for 75 min with 50% CO2, and for 10 min with 20% CO2. The maximum PaCO2 was 320 mm Hg. Cerebral intracellular lactate, pHi, and high-energy phosphate metabolites were monitored in vivo with 31P and 1H nuclear magnetic resonance (NMR) spectroscopy, using a 4.7-T horizontal instrument. Within 6 min after the administration of 50% CO2, pHi fell by 0.57 +/- 0.03 unit, phosphocreatine decreased by approximately 20%, and Pi increased by approximately 100%. These values were stable throughout the remainder of the hypercapnic period. Cerebral intracellular lactate, visible with 1H NMR spectroscopy in the hyperoxic state, decreased during hypercapnia, suggesting either a favorable change in oxygen availability (decreased lactate production) or an increase in lactate clearance or both. All hypercapnic animals awakened and behaved normally after CO2 was discontinued. Histological examination of cortical and hippocampal areas, prepared using a hematoxylin and eosin stain, showed no areas of necrosis and no glial infiltrates. However, isolated, scattered, dark-staining, shrunken neurons were detected both in control animals (no exposure to hypercapnia) and in animals that had been hypercapnic. This subtle histological change could represent an artifact resulting from imperfect perfusion-fixation, or it could represent subtle neurologic injury during the hypercapnia protocol. In summary, extreme hypercapnia and low pHi (approximately 6.5) are well tolerated in rats for periods up to 75 min if adequate oxygenation is maintained.(ABSTRACT TRUNCATED AT 250 WORDS)

Weak binding of divalent cations to plasma gelsolin

Calcium binding of swine plasma gelsolin was examined. When applied to ion-exchange chromatography, its elution volume was drastically altered depending on the free Ca2+ concentration of the medium. The presence of two classes of Ca2+ binding sites, high-affinity sites (Kd = 7 microM) and low-affinity sites (Kd = 1 mM), was suggested from the concentration dependence of the elution volume. The tight binding sites were specific for Ca2+. The weakly bound Ca2+ could be replaced by Mg2+ once the tight binding sites were occupied with Ca2+. The binding of metal ions was totally reversible. Circular dichroism measurement of plasma gelsolin indicated that most change in secondary structure was associated with Ca2+ binding to the high-affinity sites. Binding of Mg2+ to the low-affinity sites caused a secondary structural change different from that caused by Ca2+ bound to the high-affinity sites. Gel permeation chromatography exhibited a small change in Stokes radius with and without Ca2+. Microheterogeneity revealed by isoelectric focusing did not relate to the presence of two classes of Ca2+ binding sites. These results indicated that plasma gelsolin drastically altered its surface charge property due to binding of Ca2+ or Ca2+, Mg2+ with a concomitant conformational change.