GD2 and its biosynthetic enzyme GD3 synthase promote tumorigenesis in prostate cancer by regulating cancer stem cell behavior

While better management of loco-regional prostate cancer (PC) has greatly improved survival, advanced PC remains a major cause of cancer deaths. Identification of novel targetable pathways that contribute to tumor progression in PC could open new therapeutic options. The di-ganglioside GD2 is a target of FDA-approved antibody therapies in neuroblastoma, but the role of GD2 in PC is unexplored. Here, we show that GD2 is expressed in a small subpopulation of PC cells in a subset of patients and a higher proportion of metastatic tumors. Variable levels of cell surface GD2 expression were seen on many PC cell lines, and the expression was highly upregulated by experimental induction of lineage progression or enzalutamide resistance in CRPC cell models. GD2high cell fraction was enriched upon growth of PC cells as tumorspheres and GD2high fraction was enriched in tumorsphere-forming ability. CRISPR-Cas9 knockout (KO) of the rate-limiting GD2 biosynthetic enzyme GD3 Synthase (GD3S) in GD2high CRPC cell models markedly impaired the in vitro oncogenic traits and growth as bone-implanted xenograft tumors and reduced the cancer stem cell (CSC) and epithelial-mesenchymal transition (EMT) marker expression. Our results support the potential role of GD3S and its product GD2 in promoting PC tumorigenesis by maintaining cancer stem cells and suggest the potential for GD2 targeting in advanced PC.

EHD1-dependent traffic of IGF-1 receptor to the cell surface is essential for Ewing sarcoma tumorigenesis and metastasis

Overexpression of the EPS15 Homology Domain containing 1 (EHD1) protein has been linked to tumorigenesis but whether its core function as a regulator of intracellular traffic of cell surface receptors plays a role in oncogenesis remains unknown. We establish that EHD1 is overexpressed in Ewing sarcoma (EWS), with high EHD1 mRNA expression specifying shorter patient survival. ShRNA-knockdown and CRISPR-knockout with mouse Ehd1 rescue established a requirement of EHD1 for tumorigenesis and metastasis. RTK antibody arrays identified IGF-1R as a target of EHD1 regulation in EWS. Mechanistically, we demonstrate a requirement of EHD1 for endocytic recycling and Golgi to plasma membrane traffic of IGF-1R to maintain its surface expression and downstream signaling. Conversely, EHD1 overexpression-dependent exaggerated oncogenic traits require IGF-1R expression and kinase activity. Our findings define the RTK traffic regulation as a proximal mechanism of EHD1 overexpression-dependent oncogenesis that impinges on IGF-1R in EWS, supporting the potential of IGF-1R and EHD1 co-targeting.

EHD1-dependent traffic of IGF-1 receptor to the cell surface is essential for Ewing sarcoma tumorigenesis and metastasis

Overexpression of EPS15 Homology Domain containing 1 (EHD1) has been linked to tumorigenesis but whether its core function as a regulator of intracellular traffic of cell surface receptors plays a role in oncogenesis remains unknown. We establish that EHD1 is overexpressed in Ewing sarcoma (EWS), with high EHD mRNA expression specifying shorter patient survival. ShRNA and CRISPR-knockout with mouse Ehd1 rescue established a requirement of EHD1 for tumorigenesis and metastasis. RTK antibody arrays identified the IGF-1R as a target of EHD1 regulation in EWS. Mechanistically, we demonstrate a requirement of EHD1 for endocytic recycling and Golgi to plasma membrane traffic of IGF-1R to maintain its surface expression and downstream signaling. Conversely, EHD1 overexpression-dependent exaggerated oncogenic traits require IGF-1R expression and kinase activity. Our findings define the RTK traffic regulation as a proximal mechanism of EHD1 overexpression-dependent oncogenesis that impinges on IGF-1R in EWS, supporting the potential of IGF-1R and EHD1 co-targeting.

EHD2 overexpression promotes tumorigenesis and metastasis in triple-negative breast cancer by regulating store-operated calcium entry

With nearly all cancer deaths a result of metastasis, elucidating novel pro-metastatic cellular adaptations could provide new therapeutic targets. Here, we show that overexpression of the EPS15-Homology Domain-containing 2 (EHD2) protein in a large subset of breast cancers (BCs), especially the triple-negative (TNBC) and HER2+ subtypes, correlates with shorter patient survival. The mRNAs for EHD2 and Caveolin-1/2, structural components of caveolae, show co-overexpression across breast tumors, predicting shorter survival in basal-like BC. EHD2 shRNA knockdown and CRISPR-Cas9 knockout with mouse Ehd2 rescue, in TNBC cell line models demonstrate a major positive role of EHD2 in promoting tumorigenesis and metastasis. Mechanistically, we link these roles of EHD2 to store-operated calcium entry (SOCE), with EHD2-dependent stabilization of plasma membrane caveolae ensuring high cell surface expression of the SOCE-linked calcium channel Orai1. The novel EHD2-SOCE oncogenic axis represents a potential therapeutic target in EHD2- and CAV1/2-overexpressing BC.

Abstract 2411: Di-ganglioside GD2 expression and role in promoting tumorigenicity in prostate cancer

Background & Significance: Prostate cancer (PCa) is the second leading cause of cancer deaths (~34,000 in 2021 (ACS)) in American men. Castration resistance and resistance  to the next-gen androgen receptor (AR) targeted drugs are major challenges. Castration resistance involves multiple mechanisms, including androgen-independent signaling by androgen receptor (AR)- or its variants, and lineage plasticity (LP) with AR-indifferent neuroendocrine (NE) differentiation. Identifying new vulnerabilities across these multitude mechanisms could provide new therapeutic avenues against castration-resistant PCa (CRPC). The cell-surface di-ganglioside GD2 is overexpressed in neural crest cell tumors such as neuroblastoma & melanoma and chimeric (Dinutuximab) or humanized (Naxitamab) anti-GD2 antibodies are now FDA-approved for high-risk neuroblastoma therapy. GD2 expression is reported in other cancers such as breast cancer and glioma and is linked to cancer stem cell behavior. While limited prior studies have detected GD2 expression in PCa cell lines or tumor tissues, nothing is known about the functional role of GD2 in PCa.

Objectives: We hypothesized that GD2 overexpression in PCa could play a pro-tumorigenic role and that linkage of GD2 overexpression with CRPC progression may reveal the potential of targeting GD2 for CRPC therapy.

Study Design & Results: Immunohistochemical analysis of PCa patient and patient-derived xenograft tissue microarrays (TMAs) revealed GD2 expression in a subset of tumor cells. Fluorescence-activated cell sorter analysis of PCa cell lines showed strong constitutive GD2 expression on murine CRPC cell line RM-1 (derived from mutant Ras and c-Myc overexpressing prostatic epithelial cells) and human PCa line 22Rv1 (overexpresses wild-type AR and ARv7 splice variant). GD2 expression was induced de novo upon induction of lineage plasticity in GD2-negative LNCaP C4-2 prostate adenocarcinoma cell line by shRNA knockdown (KD) of RB1 or TP53. High GD2 expression was also induced when C4-2B cells were made enzalutamide resistant (C4-2BER). Induction of GD2 expression correlated with increased expression of rate-limiting GD2 biosynthetic pathway enzyme GD3 synthase (GD3S). CRISPR-Cas9 mediated stable GD3S knockout (KO) in the RM1 cell line led to the loss of GD2 expression. The GD3S-KO RM1 cells exhibited reduced proliferation, migration, invasion, and tumor sphere forming ability compared to the control cells. Intratibial injections in castrated male C57BL/6 mice showed a significant reduction in tumor development by GD3S KO RM1 cells compared to control cells.

Conclusions: Our studies demonstrate that GD2 is expressed in a subset of prostate cancers. Cell line-based studies show that GD2 expression promotes pro-tumorigenic traits. Future studies will assess the biological roles of GD2 in PCa and the potential of targeting GD2+ CRPC with antibody-based approved therapeutic agents.

Citation Format: Aaqib M. Bhat, Bhopal C. Mohapatra, Insha Mushtaq, Sukanya Chakraborty, Samikshan Dutta, Sameer Mirza, Matthew D. Storck, Subodh M. Lele, Ming-Fong Lin, Bruce J. Trock, Karen S. Sfanos, Colm Morrissey, Eva Corey, Jonathan Melamed, Leah Cook, Kaustubh Datta, Jane Meza, Jawed Siddiqui, Surinder K. Batra, Vimla Band, Hamid Band. Di-ganglioside GD2 expression and role in promoting tumorigenicity in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2411.

Abstract 87: EHD1 is required for IGF1R-mediated oncogenic signaling in Ewing Sarcoma

Background: Ewing Sarcoma (EWS) is the second most common malignant bone tumor of children and adolescents. Patients with metastatic or recurrent disease have very poor outcomes. The receptor tyrosine kinase (RTK) insulin-like growth factor 1 receptor (IGF1R) has been implicated in EWS tumorigenesis and development of metastatic disease, with anti-IGF1R antibodies and kinase inhibitors in clinical studies. However, with only ~10% of patients achieving objective responses, delineation of novel pathways that facilitate IGF1R-driven oncogenesis in EWS could provide avenues for more effective therapy. Intracellular trafficking plays a central role in regulating RTK expression and signaling, and this pathway is frequently deregulated in cancer cells. The EPS15 homology domain-containing (EHD) proteins regulate intracellular traffic of cell surface receptors, including RTKs. We observed high frequency (67%) of EHD1 overexpression in 266 primary EWS patient tumor tissues and Kaplan-Meier survival analysis of publicly available mRNA expression data showed that high EHD1 expression was associated with shorter patient survival.

Objective: This study aims to comprehend the underlying role of EHD1 in EWS oncogenesis.

Study design: Three EHD1-expressing EWS cell lines, TC71, SKES1, and A673, were engineered with doxycycline-inducible EHD1 shRNAs to assess the impact of EHD1 knockdown (KD) on in vitro oncogenic properties. Stable EHD1-Crispr-KO and mouse EHD1-rescue TC71 and A673 cell line models were developed and characterized. Further, non-targeting control or EHD1-KD TC71 cells engineered with RFP-luciferase reporter were implanted in the tibia of nude mice in an orthotopic xenograft model and tumor growth was monitored by IVIS imaging.

Results: EHD1-KD led to a significant impairment of EWS cell proliferation, migration, invasion, soft-agar colony formation, and tumor-sphere formation in vitro and reduced tumor growth in nude mice. Using a phospho-RTK profiling antibody array, we found reduced phospho-IGF1R levels upon EHD1-KD, identifying IGF1R as a potential target of regulation by EHD1. Western blotting showed a reduction in total IGF1R levels, and flow cytometric and immunofluorescence analyses revealed a pronounced decrease in the cell surface IGF1R levels upon EHD1 KD/KO in EWS cell lines. EHD1-KO EWS cell lines also exhibited a defect in IGF1-dependent migration and proliferation, and the phenotypes were restored by mouse EHD1 rescue. IGF1R and EHD1 were found to colocalize intracellularly and to co-immunoprecipitate after IGF1 stimulation. Finally, EHD1 depletion was found to impair the IGF-1R-mediated activation of downstream AKT and MAPK pathways.

Conclusion: Our studies indicate a novel requirement of the intracellular traffic regulator EHD1 in sustaining IGF1R mediated oncogenesis in EWS. Future studies will aim to evaluate dual targeting of EHD1 and IGF1R in EWS.

Citation Format: Sukanya Chakraborty, Bhopal C. Mohapatra, Sameer Mirza, Aaqib M. Bhat, Matthew D. Storck, Isidro Machado, José Antonio López, Antonio Llomart Bosch, Donald W. Coulter, Gargi Ghosal, Vimla Band, Hamid Band. EHD1 is required for IGF1R-mediated oncogenic signaling in Ewing Sarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 87.

CHIP/STUB1 Ubiquitin Ligase Functions as a Negative Regulator of ErbB2 by Promoting Its Early Post-Biosynthesis Degradation

Simple Summary

Overexpressed ErbB2/HER2 receptor drives up to a quarter of breast cancers. One aspect of ErbB2 biology that is poorly understood is how it reaches the cell surface following biosynthesis in the endoplasmic reticulum (ER). Here, the authors show that the CHIP (C-terminus of HSC70-Interacting protein)/STUB1 (STIP1-homologous U-Box containing protein 1) protein targets the newly synthesized ErbB2 for ubiquitin/proteasome-dependent degradation in the ER and Golgi, identifying a novel mechanism that negatively regulates cell surface expression of ErbB2. These findings provide one explanation for frequent loss of CHIP expression is ErbB2-overexpressing breast cancers. The authors further show that ErbB2-overexpressing breast cancer cells with low CHIP expression exhibit higher ER stress inducibility, and ER stress-inducing anticancer drug Bortezomib synergizes with ErbB2-targeted humanized antibody Trastuzumab to inhibit cancer cell proliferation. These new insights suggest that reduced CHIP expression may specify ErbB2-overexpressing breast cancers suitable for combined treatment with Trastuzumab and ER stress inducing agents.

Abstract

Overexpression of the epidermal growth factor receptor (EGFR) family member ErbB2 (HER2) drives oncogenesis in up to 25% of invasive breast cancers. ErbB2 expression at the cell surface is required for oncogenesis but mechanisms that ensure the optimal cell surface display of overexpressed ErbB2 following its biosynthesis in the endoplasmic reticulum are poorly understood. ErbB2 is dependent on continuous association with HSP90 molecular chaperone for its stability and function as an oncogenic driver. Here, we use knockdown and overexpression studies to show that the HSP90/HSC70-interacting negative co-chaperone CHIP (C-terminus of HSC70-Interacting protein)/STUB1 (STIP1-homologous U-Box containing protein 1) targets the newly synthesized, HSP90/HSC70-associated, ErbB2 for ubiquitin/proteasome-dependent degradation in the endoplasmic reticulum and Golgi, thus identifying a novel mechanism that negatively regulates cell surface ErbB2 levels in breast cancer cells, consistent with frequent loss of CHIP expression previously reported in ErbB2-overexpressing breast cancers. ErbB2-overexpressing breast cancer cells with low CHIP expression exhibited higher endoplasmic reticulum stress inducibility. Accordingly, the endoplasmic reticulum stress-inducing anticancer drug Bortezomib combined with ErbB2-targeted humanized antibody Trastuzumab showed synergistic inhibition of ErbB2-overexpressing breast cancer cell proliferation. Our findings reveal new insights into mechanisms that control the surface expression of overexpressed ErbB2 and suggest that reduced CHIP expression may specify ErbB2-overexpressing breast cancers suitable for combined treatment with Trastuzumab and ER stress inducing agents.

Nanoparticle Formulation of Indocyanine Green Improves Image-Guided Surgery in a Murine Model of Breast Cancer

PURPOSE

Negative surgical margins (NSMs) have favorable prognostic implications in breast tumor resection surgery. Fluorescence image-guided surgery (FIGS) has the ability to delineate surgical margins in real time, potentially improving the completeness of tumor resection. We have recently developed indocyanine green (ICG)-loaded self-assembled hyaluronic acid (HA) nanoparticles (NanoICG) for solid tumor imaging, which were shown to enhance intraoperative contrast.

PROCEDURES

This study sought to assess the efficacy of NanoICG on completeness of breast tumor resection and post-surgical survival. BALB/c mice bearing iRFP⁺/luciferase⁺ 4T1 syngeneic breast tumors were administered NanoICG or ICG, underwent FIGS, and were compared to bright light surgery (BLS) and sham controls.

RESULTS

NanoICG increased the number of complete resections and improved tumor-free survival. This was a product of improved intraoperative contrast enhancement and the identification of a greater number of small, occult lesions than ICG and BLS. Additionally, NanoICG identified chest wall invasion and predicted recurrence in a model of late-stage breast cancer.

CONCLUSIONS

NanoICG is an efficacious intraoperative contrast agent and could potentially improve surgical outcomes in breast cancer.

Sarcoptic mange in dogs: Its effect on liver, oxidative stress, trace minerals and vitamins

The present study was aimed to determine the effect on liver, associated oxidative stress, trace element and vitamin alteration in dogs with sarcoptic mange. A total of 24 dogs with clinically established diagnosis of sarcoptic mange, divided into two groups, severely infested group (n=9) and mild/moderately infested group (n=15), according to the extent of skin lesions caused by sarcoptic mange and 6 dogs as control group were included in the present study. In comparison to healthy control hemoglobin, PCV, and TEC were significantly (P<0.05) decreased in dogs with sarcoptic mange however, significant increase in TLC along with neutrophilia and lymphopenia was observed only in severely infested dogs. The albumin, glucose and cholesterol were significantly (P<0.05) decreased and globulin, ALT, AST and bilirubin were significantly (P<0.05) increased in severely infested dogs when compared to other two groups. Malondialdehyde (MDA) levels were significantly (P<0.01) higher in dogs with sarcoptic mange, with levels highest in severely infested groups. Activity of superoxide dismutase (SOD) (P<0.05) and catalase were significantly (P<0.01) lower in sarcoptic infested dogs when compared with the healthy control group. Zinc and copper levels in dogs with sarcoptic mange were significantly (P<0.05) lower when compared with healthy control group with the levels lowest in severely infested group. Vitamin A and vitamin C levels were significantly (P<0.05) lower in sarcoptic infested dogs when compared to healthy control. From the present study, it was concluded that sarcoptic mange in dogs affects the liver and the infestation is associated with oxidant/anti-oxidant imbalance, significant alteration in trace elements and vitamins.

Infective endocarditis in the premature neonate

We describe a series of 11 high-risk neonates with infective endocarditis (IE) in this retrospective review. Previously IE has rarely been diagnosed in newborns and is usually fatal. The frequency was 4.3 cases per 100 patients. Five patients survived. Microorganisms included gram positives such as S. aureus and coagulase-negative Staphylococcus, gram negatives such as Klebsiella pneumoniae, Enterobacter cloacae, Enterococcus faecalis, Serratia marcescens, and Acinetobacter calcoaceticus. Echocardiographic location of the lesions showed four left sided, five right sided, and two bilateral. We conclude that IE may be more common than previously described. Prompt diagnosis and treatment led to survival in 45% of our patients. Prospective studies are needed to identify patients at risk and to establish the true incidence of IE in high-risk neonates.

Effect of beta-blockade on symptomatic dexamethasone-induced hypertrophic obstructive cardiomyopathy in premature infants: three case reports and literature review

OBJECTIVE

The objective of this study was to assess the efficacy of beta-blockade on clinically significant left ventricular outflow tract obstruction in premature infants treated with dexamethasone because of bronchopulmonary dysplasia.

STUDY DESIGN

Case reports are presented of three premature infants (mean gestational age 27 weeks) cared for in the intensive care nursery in whom clinically significant septal hypertrophy and left ventricular outflow tract obstruction developed during dexamethasone treatment for bronchopulmonary dysplasia. The infants were treated with oral propranolol. Serial physiologic and echocardiographic parameters were followed. Physiologic data were analyzed with an analysis of variance, with the Kruskal-Wallis test used for nonparametric data. A p value < 0.05 was considered statistically significant.

RESULTS

Oral administration of the beta-blocker propranolol resulted in clinical and echocardiographic improvement of the left ventricular outflow tract obstruction. One patient had a lower average heart rate and two patients had lower average mean blood pressure values during propranolol treatment, none of which was clinically significant. None of the patients had worsening of the respiratory status.

CONCLUSION

beta-blockade treatment was well tolerated and may be beneficial in relieving symptomatic steroid-induced left ventricular outflow tract obstruction in premature infants.

Transcatheter radiofrequency ablation for congenital junctional ectopic tachycardia in infancy

Congenital junctional ectopic tachycardia (JET) is a difficult to treat arrhythmia with a variably poor response to pharmacologic intervention. We report on the successful treatment of a 17-day-old infant with JET via transcatheter radiofrequency ablation of the arrhythmogenic focus resulting in resolution of the tachycardia and maintenance of normal atrioventricular nodal function. Transcatheter radiofrequency ablation techniques should be considered in infants with life-threatening arrhythmia recalcitrant to standard forms of drug therapy.

Infective endocarditis in infants and children

Due to changing characteristics of infective endocarditis in the past two decades, we, retrospectively analysed 28 cases of infective endocarditis in children of age less than 15 years at Sher-i-Kashmir Institute of Medical Sciences, Soura, Srinagar from December, 1983 to November, 1993. The incidence of disease was observed as 1.5 cases/1000 children admitted with a M:F ratio of 2:1. Three patients were of age less than 2 years (group I) as 25 were above 2 years of age (group II). The two groups had significant difference in portal of entry of infection, infective microorganisms, echocardiography and prognosis. Congenital heart disease was the commonest underlying cardiac lesion in 24 (85.71%) patients. Portal of entry of infection was apparent in 35.71% only; dental route being more frequent in group II. Streptococcus viridans (in 9 cases) followed by staphylococcus aureus (in 4 cases) were the two common organisms isolated. Patients were treated, for a period of 4-6 weeks with a over all mortality rate of 25%. Factors associated with poor prognosis were age < 2 years, staphylococcal infection ad negative blood cultures. Heart failure resistant to medical therapy was a leading cause of death.

Umbilical venous catheters: evaluation of radiographs to determine position and associated complications of malpositioned umbilical venous catheters

To evaluate the ability of radiography to detect malpositioned umbilical venous catheters in the left atrium and to determine the frequency of associated complications, we retrospectively compared radiographs and echocardiograms of 31 infants who had malpositioned catheters in the left atrium by echocardiography (cases) and 31 infants who had properly positioned catheters (controls). The case and control infants were of similar gestational age and birthweight (gestational age, 32 +/- 5 weeks; birthweight, 1672 +/- 899 g for cases; gestational age, 31 +/- 5 weeks; birthweight, 1666 +/- 958 g for controls). Malposition was defined as the catheter tip above the seventh thoracic vertebra by radiography. Radiography had sensitivity of 45%, specificity of 87%, positive predictive value of 77%, negative predictive value of 61%, accuracy of 66%, and prevalence of 50%. Thrombus formation in the heart was detected in 8 of 31 (26%) of cases and in 1 of 31 (3%) of controls (p = 0.03). The incidence of complications, such as necrotizing enterocolitis, culture-positive sepsis, total number of sepsis cases, thrombocytopenia, embolism to extremities, and hematuria were similar in both groups (difference not significant). These results suggest that radiography is unreliable in determining incorrect catheter placement. Catheters malpositioned in the left atrium were associated with thrombus formation. There was no significant increase in systemic complications in the infants with a malpositioned catheter.

Myocardial protection during ischemia by prior feeding with the creatine analog: cyclocreatine

The ability of 1-carboxymethyl-2-iminoimidazolidine (cyclocreatine), a synthetic creatine analog, to protect myocardium during global ischemia was assessed in isovolumic rat hearts using phosphorus-31 nuclear magnetic resonance spectroscopy. Wistar rats were fed a 1% cyclocreatine diet. After 2 weeks, cyclocreatine-fed (n = 8) and control (n = 7) rats were anesthetized, the heart was excised and retrograde perfusion was begun at 10 ml/min per g with 37 degrees C, phosphate-free buffer containing glucose and oxygen. Hemodynamic and spectroscopic data were obtained during baseline, ischemia and recovery periods (each 24 min). During ischemia, the heart of control rats developed a rigor-like increase in tonic pressure (ischemic contracture) not seen in the heart of cyclocreatine-fed rats (22 versus 1 mm Hg, p less than 0.01). This change was associated with significantly more adenosine triphosphate (ATP) at end-ischemia in the cyclocreatine group (1.6 versus 0.6 mumol/g, p less than 0.01) and delayed development of acidosis (p less than 0.001). With reperfusion, the heart of cyclocreatine-fed rats spontaneously defibrillated sooner than did the heart in control rats (178 versus 346 s, p less than 0.03). Diastolic pressure remained significantly elevated throughout recovery in control hearts compared with treated hearts (p less than 0.001). Prior feeding with cyclocreatine preserves myocardial adenosine triphosphate during ischemia, delays the development of acidosis and ischemic contracture and improves recovery of mechanical function on reperfusion.

Protective effect of the specific thromboxane receptor antagonist, BM-13505, in reperfusion injury following acute myocardial ischemia in cats

The ability of BM-13505, 4-[2-(4-chlorobenzenesulfonylamino) ethyl]-benzene acetic acid), a specific thromboxane/endoperoxide receptor antagonist, to protect the myocardium against ischemia and reperfusion injury, was assessed in an anesthetized cat model. Cats were rendered ischemic by left anterior descending (LAD) coronary artery ligation for 1 1/2 hours followed by reperfusion for 4 1/2 hours. BM-13505 or its vehicle (i.e., Na2CO3) was administered intravenously 30 minutes before reperfusion at a rate of 1 mg/kg followed by 1 mg/kg/hr. BM-13505 significantly (p less than 0.001) reduced the area of ischemic tissue as a percent of total left ventricular mass and total area at risk, without altering basic hemodynamics (i.e., arterial blood pressure, heart rate, or their product) and thereby not influencing myocardial oxygen demand. The mechanism of the protective effect of the thromboxane receptor antagonist appears to be cytoprotective but may involve the prevention of neutrophil-induced cellular damage.

Heart rate and coronary flow effects on the cardiac response to sympathetic stimulation

We studied the effects of changes in heart rate and coronary blood flow on the decay of the cardiac inotropic response to sympathetic stimulation in 10 anesthetized dogs. After we induced complete heart block, we paced the ventricles at rates of 90, 120 and 150.min-1. At each pacing frequency, we perfused the left main coronary artery with blood at a baseline flow and at a flow 85% above the baseline rate. At each combination of pacing frequency and flow, we stimulated the left ansa subclavia supramaximally at a frequency of 5 Hz for 2 min. To assess the rate of norepinephrine removal from the ventricular myocardium, we measured the 50% decay time of the left ventricular inotropic response [(dP/dt)max] immediately after cessation of sympathetic stimulation. We found that the inotropic response decayed faster (P = 0.03) when the coronary artery blood flow was high than when the flow was baseline. The effect of heart rate on the decay of the left ventricular inotropic response depended on the level of the coronary blood flow. When the blood flow was baseline, the inotropic response decayed more rapidly (P = 0.001) when the heart rate was 150.min-1 than when it was 90 or 120.min-1. However, when the flow was high, heart rate did not affect the response decay significantly. We conclude that the mechanical contraction of the ventricles facilitates the washout of norepinephrine from the cardiac interstitium and into the coronary circulation by virtue of a massaging action.

Increased heart rate accelerates norepinephrine washout from normal myocardium

We determined whether a change in heart rate affected the decay of the ventricular inotropic response to sympathetic stimulation in an experimental group and in a control group of anesthetized dogs. We induced complete heart block in each animal and paced the ventricles at rates of 90, 120, and 150 min-1 during two observation periods. In the experimental group, desipramine hydrochloride was given during the second period to block the neuronal uptake mechanism. The control animals did not receive desipramine during either period. The time required for the ventricular inotropic response to decay by 50% after cessation of a 2-min train of sympathetic stimulation was used as an index of the rate of norepinephrine washout from the myocardial interstitium. As we increased the pacing rate over the range of 90-150 min-1 in the experimental group, the mean decay half times (+/- SE) decreased by 36 +/- 4% (P less than 0.001) before desipramine and by 26 +/- 6% (P less than 0.001) in the presence of desipramine. These decrements in the decay half times were not significantly different from each other. The mean decay half times decreased by 36 +/- 4% (P less than 0.001) in the control dogs; the effects did not change appreciably from the first to the second observation period. We conclude that an increase in pacing frequency facilitates the washout of norepinephrine from the ventricular myocardium; this facilitation is equally pronounced regardless of whether the neuronal uptake mechanism is intact or suppressed.

Left ventricular systolic circular index: an echocardiographic measure of transseptal pressure ratio

An echocardiographic index of left ventricular (LV) short axis circularity can be defined by the equation: left ventricular systolic circularity index (LVSCI) = 4 pi(LV area) X 100/(LV perimeter). This index was measured from two-dimensional echocardiograms in 98 children (ages 1 day to 19 years) with congenital heart disease, and results were compared to right ventricular/left ventricular peak systolic pressure ratios (RVP/LVP) determined at cardiac catheterization. LVSCI was also computed in 50 children without cardiovascular or pulmonary disease to define the normal range. A short axis image of the left ventricle at the level of the papillary muscles was obtained from the left parasternal position. Area and perimeter were determined by computer planimetry of the LV endocardium at end systole. LVSCI was measured from three consecutive beats and averaged. In the normal group all values of LVSCI exceeded 93% (mean 96%). In the group with congenital heart disease RVP/LVP correlated exponentially with LVSCI: RVP/LVP = e2.6-0.04 LVSCI; with r = 0.88, SEE = 0.39, and p less than 0.001. If patients with suprasystemic right ventricular pressures (RVP/LVP greater than 1.2) are excluded, there is a linear correlation between RVP/LVP and LVSCI: RVP/LVP = 2.3-0.021 LVSCI; with r = 0.80, SEE = 0.14, and p less than 0.001. LVSCI could distinguish between patients with normal, mildly elevated, moderately elevated, and severely elevated RVP/LVP. We conclude that LVSCI is a readily determined parameter that is independent of age or body size and predicts RVP/LVP in children with congenital heart disease.

Mass spectrometer monitoring of expired carbon dioxide in critically ill neonates

Seventy-five paired comparisons of expired carbon dioxide tension (PECO2) and PaCO2 were obtained to evaluate the clinical usefulness of a mass spectrometer for monitoring PECO2 in critically ill neonates and to explore the factors that influence the PaCO2-PECO2 gradient. Nine neonates with a mean birth weight of 2.18 kg and a mean gestational age of 34 wk were studied during continuous positive-pressure ventilation. When PaCO2 was between 26 and 50 torr, this variable was linearly related to PECO2 by the equation: PaCO2 = 23.42 + .50 PECO2, r = +0.69 (p less than .001). Mean daily gradients for severe pulmonary disease (n = 9; mean 10.5 +/- 4.4 [SD] torr) were significantly (p less than .01) higher than those for moderate disease (n = 10; mean 3.9 +/- 3.1 torr); however, 61.3% of the gradients were no greater than 10 torr. Expiratory times no greater than 1.0 sec were associated with significantly (p less than .001) higher gradients (n = 33; mean 12.2 +/- 3.8 torr) than those over 1.0 sec (n = 42; mean 5.4 +/- 4.9 torr). This was, in part, due to the response time of the mass spectrometer system (0.68 sec to 63% of a step change in CO2). The continuous monitoring of PECO2 was especially helpful in the care of two neonates. We hypothesize that a decrease in the response time would improve the correlation between PaCO2 and PECO2 and thereby enhance the usefulness of this device as a trend monitor.

Alimentary absorption of gentamicin in preterm infants

Fifty-two preterm neonates receiving oral gentamicin from birth, as prophylaxis against necrotizing enterocolitis (NEC), had serum gentamicin levels measured on the second day of life (52 infants) and on the seventh to tenth days (43 infants). The serum gentamicin concentrations on the second day were 0.5 microgram/ml or less in 21 percent, 0.6 to 1.0 microgram/ml in 15 percent, 1.1 to 2 micrograms/ml in 34 percent, 2.1 to 5 micrograms/ml in 25 percent, and 5 to 7.1 micrograms/ml in 4 percent of the infants. Paired serum gentamicin levels were significantly lower (p less than 0.001) on the seventh to tenth day as compared to the second day. We conclude that preterm infants in the first few days of life absorb orally administered gentamicin. Concomitant use of systemic gentamicin under such circumstances may potentially lead to toxic serum gentamicin concentration.

The importance of the FSH/LH ratio in ovarian stimulation therapy regime for in vitro fertilization

In a retrospective study batches of hMG with different FSH/LH ratios, as well as pure FSH were used in two different stimulation protocols (Clomiphene/hMG and hMG only). The aim of this paper was to study the effect and importance of the different FSH/LH ratios if any, in ovarian stimulation during the follicular phase on the success of IVF. The results of our preliminary study indicate that as far as ovarian stimulation with Clomiphene/hMG is concerned, there seems to be no significant beneficial effect on IVF success of using pure FSH or gonadotropin preparations with higher FSH/LH ratios. With gonadotropin only for ovarian stimulation however, the use of high FSH/LH ratio seems to significantly increase the pregnancy rate.

Fatal adenoviral (type 7) respiratory disease in neonates

Two cases of fatal neonatal adenoviral type 7 respiratory disease are described. The clinical, laboratory, x-ray, and pathological features of these two neonates and those reported in the literature are highlighted. Suggestions are made regarding how to diagnose this disease early so that the patients can be isolated and further spread of the disease prevented.

Effect of theophylline on neurotransmitters in preterm infants with apnea

Urinary excretion of various catecholamine metabolites (4-hydroxy-3-methoxymandelic acid, homovanillic acid, 3-methoxy-4-hydroxphenylglycol) was studied in preterm infants with idiopathic apnea treated with theophylline. Relief of apnea in these infants was not associated with significant increase in the urinary excretion of various metabolites. We suggest that theophylline does not seem to relieve apnea of prematurity by the stimulation of peripheral catecholamine systems.

Cerebrospinal fluid concentration of biogenic amine metabolites in idiopathic apnea of prematurity

The concentration of homovanillic acid and 3-methoxy-4-hydroxyphenylglycol (MHPG), the major metabolites of dopamine and norepinephrine, respectively, were studied in the cerebrospinal fluid (CSF) of 34 newborn infants. No significant difference was found in the levels of MHPG and homovanillic acid between preterm and term infants. Apneic preterm infants had significantly higher levels of MHPG than nonapneic prematures. Theophylline did not change the levels of these metabolites in CSF. There was a progressive rise of MHPG levels in CSF in preterm infants as their postnatal age increased. We suggest that idiopathic apnea of prematurity is not associated with depletion of catecholamine stores in the central nervous system. Theophylline does not seem to relieve apnea by stimulation of the central adrenergic system.

Study of neurotransmitters in premature infants with or without apnea of prematurity

Twelve-hour urinary excretion of 4-hydroxy-3-methoxymandelic acid (VMA), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) was studied in 20 premature infants, 8 without apnea and 12 with apnea. All infants were studied at 1-3 days of postnatal age (before apnea). Nonapneic infants were restudied at 10-15 days of postnatal age. Apneic infants were also restudied 24 h after apnea. Apnea was not associated with decreased urinary excretion of VMA and MHPG. Only HVA, when expressed as microgram/kg body weight, was significantly lower after the onset of apnea. This difference disappeared when HVA was expressed as microgram/mg creatinine. We suggest that apnea of prematurity may not be related to the immaturity of catecholamine pathways.

The pattern of eosinophilia in premature infants. A prospective study in premature infants using the absolute eosinophil count

The incidence and severity of eosinophilia was prospectively studied in 45 premature infants, who were divided into three groups according to their gestational age. The incidence and severity of eosinophilia was higher in small preterm infants. A significantly higher number of infants with eosinophilia received total parenteral nutrition, endotracheal intubation, or blood transfusions. The duration of total parenteral nutrition or endotracheal intubation and the number of blood transfusions were also significantly higher in infants with eosinophilia. Eosinophilia in premature infants is not associated with neutropenia.