LAG-3 is expressed on a majority of tumor infiltrating lymphocytes in pediatric Hodgkin lymphoma

LAG-3, through interaction with a variety of ligands, regulates T cell function via inhibition of T cell proliferation and activation. It has been demonstrated to be overexpressed on tumor infiltrating lymphocytes (TILs) of a variety of cancers with associated poor outcomes. The purpose of this study is to characterize the expression pattern and clinical significance of LAG-3 in pediatric Hodgkin lymphoma (HL). Patient tumor samples from Children's Oncology Group clinical trial AHOD0031 with matched patient outcome data were analyzed for the expression of LAG-3 and PD-L1 using immunohistochemistry. 73/115 patients (63%) demonstrated positive LAG-3 staining. No demographic or survival outcome data were significantly associated with LAG-3 expression. Interestingly, patients with the lowest density of expression were found to have the worst EFS, and those with highest density of expression demonstrated the best EFS. There was a positive statistically significant relationship between presence of LAG-3 and PD-L1 expression. This project is innovative in its characterization of LAG-3 as an immune checkpoint target in pediatric HL.

Detection of graft fibrosis by vibration-controlled transient elastography in pediatric liver transplant recipients

Pediatric liver transplant recipients are at risk of developing graft fibrosis which can affect patient survival. VCTE is a non-invasive tool that measures LSM and has been shown to correlate with hepatic fibrosis. The aim of this study was to therefore evaluate the ability of LSM to predict fibrosis in pediatric liver transplant recipients with different graft types. We performed a cross-sectional study evaluating LSM of 28 pediatric liver transplant recipients who underwent a total of 20 liver biopsies within 1 month of LSM. LSM was compared to liver histology as well as graft type: WL or PL. The median LSM of all post-transplant patients was 5.6 kPa (range = 2.7-18.3). There was a statistically significant correlation between LSM and METAVIR fibrosis score (P = .001) and LAF score (P < .001). There was no difference in LSM between graft type (P = .088). The AUROC curve for LSM predicting any significant fibrosis (F ≥ 2) was 0.863. A cutoff value of 7.25 had a sensitivity of 71%, specificity of 100%, NPV of 87%, and PPV of 100% for significant fibrosis. LSM by VCTE is feasible in pediatric liver transplant recipients regardless of graft type. We found a significant correlation between LSM and hepatic fibrosis and established a cutoff value that may help determine which patients warrant further evaluation for graft fibrosis.

Abstract A17: HHLA2 is a new immune checkpoint expressed in pediatric Hodgkin lymphoma

Purpose: To identify new pharmacologically targetable immune checkpoints in pediatric Hodgkin lymphoma.

Background: The role of PD-1/PD-L1 axis in Hodgkin lymphoma (HL) has led to FDA approval for use of inhibitors of this pathway in chemotherapy-refractory HL. There are numerous additional B7/CD28 immune checkpoints that may similarly represent useful targets but have not yet been evaluated in HL. HHLA-2 is the newest member of the B7/CD28 family of immune checkpoint regulators that typically help tumor immune escape via inhibition T-cell activity and tumor killing. The prevalence of HHLA-2 has been demonstrated with expression on a wide range of adult cancers, with associated poor outcomes. HHLA-2 has yet to be evaluated in pediatric cancers, except for osteosarcoma where it was found to have increased expression and associated with worse five-year EFS. The purpose of this study is to characterize the expression pattern and clinical significance of HHLA-2 in pediatric HL using immunohistochemistry.

Methods: Patient tumor samples from prior Children’s Oncology Group clinical trials with matched patient outcome data containing over 300 patient samples were obtained. 95% confidence intervals were calculated based on a range of observed prevalence of immune checkpoint expression for this initial pilot cohort of 100 samples. Using immunohistochemistry, paraffin-embedded samples were tested for the expression of HHLA-2 and B7x. Samples were also stained for CD30 to better delineate Reed Sternberg cells (RS) from the remainder of the tumor microenvironment. Immune checkpoint staining was compared to known positive controls of A204 cell line for HHLA-2 and SKBR3 for B7x, and negative controls of 3T3 cells. Expression intensity was scored by a pediatric pathologist.

Results: The initial tissue microarray contained 128 unique HL cases; only 121 tissue samples were evaluable as HL tissue. Samples from 52 patients demonstrated positive HHLA-2 staining (43%); however, there was no identifiable B7x staining. HHLA-2 staining ranged from weak to moderate, with 23% (12/52) of positive samples demonstrating moderate staining. RS staining was observed in 77% of samples (40/52), with the remaining samples containing positively staining lymphocytes.

Conclusion: This project is innovative in its characterization of HHLA-2 as a novel immune checkpoint target in pediatric HL. With these preliminary results we will validate these results with the remaining 200 patient samples and explore the relationship of expression with standard tumor characteristics, including stage and patient outcomes such as ESF and OS. These results can help discover new prognostic biomarkers and guide future treatment as therapeutic antibodies are currently being developed. We hope that the information from this project will be used to support new clinical trials for pediatric patients with Hodgkin lymphoma.

Citation Format: Scott Moerdler, Damini Chand, Michelle Ewart, XingXing Zang, Peter Cole. HHLA2 is a new immune checkpoint expressed in pediatric Hodgkin lymphoma [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr A17.

LAG-3 overexpression in pediatric Hodgkin lymphoma

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Background: The role of the PD-1/PD-L1 axis in Hodgkin Lymphoma (HL) has led to FDA approval for use of inhibitors in chemotherapy-refractory HL. Numerous additional immune checkpoints may be useful targets, but have not yet been evaluated in HL. LAG-3, a related checkpoint, has been demonstrated to be overexpressed on tumor infiltrating lymphocytes (TILs) of a variety of cancers with associated poor outcomes. LAG-3 is known to inhibit T cell proliferation and activation, representing a possible therapeutic pathway for anti-tumor immunity. However, LAG-3 has yet to be evaluated in pediatric cancers. The purpose of this study is to characterize the expression pattern and clinical significance of LAG-3 in pediatric HL using immunohistochemistry. Methods: Patient tumor samples from prior Children’s Oncology Group clinical trials (AHOD0031) with matched patient outcome data containing 200 patient samples were obtained. 95% confidence intervals were calculated based on a range of observed prevalence of immune checkpoint expression. Using immunohistochemistry, paraffin embedded samples were tested for the expression of LAG-3 and PD-L1. Samples were stained for CD30 to better delineate Reed Sternberg cells from the remainder of the tumor microenvironment. Immune checkpoint staining was compared to positive controls of normal tonsil tissue, and negative controls of 3T3 cells. Expression intensity was scored by a Pediatric Pathologist. Results: 115 unique HL patient cases with evaluable HL tissue and correlating clinical outcome data were analyzed. Samples from 73/115 patients (63%) demonstrated positive LAG-3 staining, defined as over 10% of TILs expressing LAG-3. No demographic data including gender, race/ethnicity, age, or stage were significantly associated with LAG-3 expression. While not statistically significant there was a numerical difference in event free survival (EFS) and patients with LAG-3 expression demonstrated worse EFS. In terms of degree of LAG-3 expression, patients with the lowest positive expression were found to have the worst EFS, and those with highest expression demonstrated the best EFS. 97% of patient cases were found to be PD-L1 positive. 71/73 (97%) of patients who expressed LAG3 were also PDL1+, and 71/106 (67%) of PDL1+ cases were also LAG3+. LAG-3 and PD-L1 were found to be independent (p = 0.09). Conclusions: This project is innovative in its characterization of LAG-3 as an immune checkpoint target in pediatric HL. We hope that the information from this project will be used to support new clinical trials for pediatric patients with Hodgkin lymphoma.

Multifocal primary neuroblastoma tumor heterogeneity in siblings with co-occurring PHOX2B and NF1 genetic aberrations

Neuroblastoma, the most common extracranial solid tumor of childhood, can present in multiple primary sites, but the extent of genetic heterogeneity among tumor foci, as well as the presence or absence of common oncogenic drivers, remains unknown. Although PHOX2B genetic aberrations can cause familial neuroblastoma, they demonstrate incomplete penetrance with respect to neuroblastoma pathogenesis, suggesting that additional undescribed oncogenic drivers are necessary for tumor development. We performed comprehensive molecular characterization of neuroblastoma tumors from two siblings affected by familial multifocal neuroblastoma, including whole exome sequencing and single-nucleotide polymorphism (SNP) arrays of tumor and matched blood samples. Data were processed and analyzed using established bioinformatics algorithms to evaluate for germline and somatic mutations and copy number variations (CNVs). We confirmed the presence of a PHOX2B deletion and NF1 mutation across all tumor samples and the germline genome. Matched tumor-blood whole exome sequencing also identified 365 genes that contained nonsilent coding mutations across all tumor samples, with no recurrent mutations across all tumors. SNP arrays also showed significant heterogeneity with respect to CNVs. The only common CNV across all tumors was 17q gain, with differing chromosomal coordinates across samples but a common region of overlap distal to 17q21.31, suggesting this adverse prognostic biomarker may offer insight about additional drivers for multifocal neuroblastoma in patients with germline PHOX2B or NF1 aberrations. Molecular characterization of all tumors from patients with multifocal primary neuroblastoma has potential to yield novel insights on neuroblastoma pathogenesis.

Novel mutations in NOTCH2 gene in infants with neonatal cholestasis

One cause of neonatal cholestasis (NC) is paucity of intrahepatic bile ducts which can be associated with Alagille syndrome or non- syndromic. Alagille syndrome is caused by autosomal dominant mutations in the Notch signaling pathway ligand Jagged1 in 94% of patients and mutations in the NOTCH2 receptor in <1% of patients. This is a retrospective case series studying infants with neonatal cholestasis found to have variants of unknown significance (VOUS) in NOTCH2. Sorting intolerant from tolerant (SIFT) and polymorphism phenotyping (PolyPhen) were utilized to predict a damaging effect. Five infants with NC without other features of Alagille syndrome were found to have one copy of a VOUS in NOTCH2, predicted to be damaging by SIFT and PolyPhen. Our cases support the notion that NOTCH2 mutations may result in hypoplastic biliary system. Further characterization of these variants is important to assist with our clinical approach to NC.

627. Differences in C. difficile Toxin A Binding in Humans: Adults vs. Infants

Background

Children less than 1 year of age are commonly colonized with toxin-producing C. difficile, but appear to be immune to the associated colitis. Animal studies suggest that young infants lack receptors for C. difficile toxin, though this has never been documented in humans.

Methods

Tissue from infants (<6 months) and adults > 21 years were studied. Toxin A binding was assessed using an indirect staining method, which included incubation with toxin A (List Labs) and detection with a rabbit polyclonal anti-sera (Lee Labs). A trained pediatric pathologist assessed the extent of staining in a blinded fashion. In other studies, toxin A was labeled with rhenium-188 and incubated with albumin-blocked tissue sections (four-infant and six-adult) for 1 hour. After washing, gamma counts were measured and the average percentage of retained radiolabeled toxin A calculated. Fisher exact tests and ANOVA were used for analyses. All studies were done in compliance with our institutional IRB.

Results

Six of 13 (46%) adult specimens were found to have reactivity on both the apical epithelial surface as well as crypt staining. Another six had reactivity localized only to the basal and lateral surface of the crypts. One specimen demonstrated no reactivity at all. For neonates (n = 15), no specimens were found to have reactivity localized to the apical epithelial surface, though four specimens had reactivity at the basal epithelial surface (P value for comparison of apical staining 0.0046) (see figure). Average percentage of retained counts for control (no tissue), infant and adult colon sections were, 0.318 ± 0.147, 0.305 ± 0.079 and 0.48 ± 0.114, respectively (P = 0.051).

Conclusion

Immunohistochemistry and radiolabelling studies indicate that neonatal colon section binds C. difficile toxin A less strongly and in a different distribution pattern (i.e., without apical staining) when compared with adult colon sections. These findings are consistent with previous animal studies and support the paradigm that a lack of toxin receptors in the infant colon contributes to immunity against C. difficile colitis. Additional studies are needed to define the presence of specific receptors and determine if a similar phenomenon applies to toxin B binding.

Disclosures

All authors: No reported disclosures.

Methods to improve the noninvasive diagnosis and assessment of disease severity in children with suspected nonalcoholic fatty liver disease (NAFLD): Study design

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is strongly associated with obesity and is the most common liver disease in the developed world. In children with suspected NAFLD, present guidelines suggest consideration of alternative diagnoses via extensive blood testing, though the yield of this work up is unknown. Furthermore, the gold standard diagnostic test for NAFLD remains liver biopsy, making the development of non-invasive tests critically important.

OBJECTIVES

Our objectives are: 1) to determine the accuracy of elastography and multiple serum biomarkers - each assessed individually and as algorithms (including those previously tested in adults) - for the diagnosis of nonalcoholic steatohepatitis (NASH) and early fibrosis in children and (2) to examine the utility of extensive testing for rare alternative diagnoses in overweight or obese children with elevated alanine aminotransferase (ALT) suspected to have NAFLD.

DESIGN

This is an ongoing, cross-sectional study in children 2-18 years of age with up to 2 years of prospective follow up. Eligible patients are asymptomatic, overweight or obese, and have an ALT ≥35 U/L upon enrollment. Two forms of elastography are obtained serially along with anthropometric data and routine laboratory tests. Elastography and serum biomarkers are also performed immediately prior to any clinically-indicated biopsy.

METHODS

Between April 2015 and April 2018, 193 children have been enrolled in this ongoing study and 71 have undergone liver biopsy. Here we carefully report the rationale, methodology, and preliminary data for this study.

Abstract 1938: Exportin-1 (XPO1) is a novel therapeutic biomarker for patients with neuroblastoma

Background: Half of patients with high-risk neuroblastoma succumb to disease, yet these patients with inferior outcome cannot be identified at diagnosis despite contemporary risk stratification that integrates MYCN copy number status, tumor histology, and patient age. We have shown that overexpression of Exportin-1 (XPO1) is associated with poor survival in neuroblastoma, affirming what has been identified across a range of malignancies. Selinexor (KPT-330, Karyopharm Therapeutics), an XPO1 inhibitor in early phase clinical trials, inhibits the nuclear to cytoplasmic translocation of tumor suppressor and growth regulatory proteins implicated in oncogenesis. We hypothesized that protein expression level of XPO1 in neuroblastoma cell lines predict the effective response of treatment with selinexor.

Methods: We used a panel of early passage patient derived neuroblastoma cell lines including IMR5, NLF, KELLY, NB-EBC1, and SKNSH that are representative of the spectrum and genetic diversity of human disease. Cell lines were treated with varying concentrations of selinexor. RNA and whole cell protein extract as well as nuclear and cytoplasmic fractionated protein was obtained from untreated and treated conditions. Treated and untreated cells were also pelleted, and, along with patient tumor samples, formalin-fixed and paraffin-embedded for microscopic and immunohistochemical (IHC) evaluation.

Results: Compared to noncancerous cell lines, neuroblastoma cell lines have high protein and mRNA expression of XPO1; higher expression correlates with greater sensitivity to selinexor. Selinexor treatment reduced XPO1 protein and increased XPO1 mRNA expression, and it lead to nuclear retention of XPO1 cargo such as p53 and survivin. Comparison of microscopic features and protein staining intensity of patient samples with known XPO1 expression is ongoing.

Conclusions: This study provides rationale for XPO1 protein abundance as a potential biomarker of therapeutic response to the drug selinexor. By using patient derived neuroblastoma cell lines, we are able to evaluate the response of selinexor and XPO1 expression in the context of this enigmatic disease. These data suggest that initial drug response to selinexor can be predicted early in the course of disease and more investigation of the high expression of XPO1 seen in patients with poor outcome will provide strategies for combinatorial treatment approaches.

Citation Format: Basia Galinski, Marcus Luxemburg, Michelle Ewart, Yosef Landesman, Daniel Weiser. Exportin-1 (XPO1) is a novel therapeutic biomarker for patients with neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1938. doi:10.1158/1538-7445.AM2017-1938

Infantile Digital Fibroma: A Rare Fibromatosis

Infantile digital fibroma is a rare benign lesion that usually occurs during the first 2 years of life. It can be multiple, but it is usually a single lesion. If it grows large enough it can cause joint deformities or interfere with everyday activities. Microscopically, the neoplastic cells usually have inclusion bodies that are best highlighted with a Masson trichrome stain but can often be seen on hematoxylin-eosin staining. Treatment for this entity is usually watchful waiting because of its ability to spontaneously regress, but excision is recommended if the lesion is symptomatic. More recently, fluorouracil or injectable steroids have shown great promise in inducing regression without the complications that accompany surgery.

Abstract 2221: HHLA2, a novel member of the B7 family of inhibitory ligands, is highly expressed in osteosarcoma

Purpose: Over the past four decades there have been minimal improvements in outcomes for patients with osteosarcoma (OS). New targets and novel therapies are needed to improve outcomes for these patients. In this study, we sought to evaluate the prevalence and prognostic utility of the immune checkpoint inhibitor HHLA2 in OS.

Experimental Design: HHLA2 expression was evaluated in two cohorts of OS patients using a tumor microarray (TMA) (n = 62) and whole slides (n = 48). HHLA2 expression was assessed in primary tumor specimens and metastatic disease, and correlated with the presence of tumor infiltrating lymphocytes (TILs), and event free survival.

Results: HHLA2 was expressed in 68% of OS tumors in the TMA and in 54% in the second cohort. HHLA2 was expressed in almost all metastatic disease specimens and was more prevalent than in primary specimens without known metastases (93% vs 53%, p = 0.02). TILs were present in 75% of all osteosarcoma specimens. Patients whose tumors were ≥25% or ≥50% HHLA2 positive had significantly worse five-year event-free-survival (33% vs 64%, p = 0.03 and 14% vs 59%, p = 0.02).

Conclusions: HHLA2 is expressed in the majority of OS tumors, is associated with metastatic disease, and is associated with poorer survival. Further studies are needed assessing the effect of HHLA2 expression on the function of the immune microenvironment, as well as assessing the feasibility and utility of targeting HHLA2 in OS.

Citation Format: Pratistha Koirala, Michael Roth, Jonathan Gill, Jordan Chinai, Michelle Ewart, Sajida Piperdi, David Geller, Bang Hoang, Yekaterina Fatakhova, Maya Ghorpade, Xingxing Zang, Richard Gorlick. HHLA2, a novel member of the B7 family of inhibitory ligands, is highly expressed in osteosarcoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2221.

Yield of diagnostic tests in obese children with an elevated alanine aminotransferase

AIM

Nonalcoholic fatty liver disease (NAFLD) is associated with obesity and affects roughly 10% of children. However, NAFLD is often diagnosed by exclusion - that is, obese children with an elevated alanine aminotransferase (ALT) are screened for other liver diseases in the absence of a biopsy. This testing is nonstandardized, and professional society recommendations differ. This study examines the yield of testing for disorders other than NAFLD in this patient population.

METHODS

A retrospective study was performed in 120 obese, asymptomatic, noncholestatic children with an ALT ≥40 U/L and additional diagnostic testing.

RESULTS

No patients were found to have Wilson's, hepatitis A, hepatitis B, hepatitis C, cytomegalovirus, alpha-1 antitrypsin deficiency, autoimmune hepatitis, celiac disease or Epstein-Barr virus. Only one patient (1/120) was identified with definite disease other than NAFLD, which was muscular dystrophy. The positive predictive value of a screening test was 5%, and the specificity was 97%. Of 70 children with an abdominal ultrasound, no significant abnormalities were identified.

CONCLUSION

Extensive testing in asymptomatic, noncholestatic, obese children with an elevated ALT may be of limited diagnostic value and false-positive tests are likely. Large, prospective studies are needed to help focus the work up in this patient population.

Expression of p63 in papillary thyroid carcinoma and in Hashimoto’s thyroiditis: a pathobiologic link?

p63 proteins are p53 homologs that are postulated to regulate squamous stem cell commitment. An immunohistochemical survey of p63 expression in normal thyroid and in reactive, neoplastic, and inflammatory thyroid disorders was performed. Sections from routinely fixed and processed archival thyroidectomy specimens were pretreated with citric acid, pH 6.0, for antigen retrieval, then incubated overnight with anti-p63 monoclonal antibody 4A4. Slides were stained using a streptavidin-biotin kit and diaminobenzidine as a chromagen, and then were counterstained with hematoxylin. The results showed that p63 expression was negative in normal thyroid tissue, nodular goiters, and oncocytic follicular adenomas. Positivity was rare and weak in follicular adenomas. p63-positive foci were commonly found in Hashimoto's thyroiditis (1 or more foci in 78.8% of cases), but rare in Graves' disease. Twenty-seven of 33 papillary thyroid carcinomas (81.8%) displayed p63-positive foci. Staining was uncommon in follicular carcinomas and rare in medullary carcinomas. One case of insular carcinoma was p63-positive. All squamoid structures were p63-positive; p63-positive structures morphologically consistent with solid cell nests were also identified. Based on the results of this study, we conclude that p63 is commonly expressed in papillary thyroid carcinoma and in Hashimoto's thyroiditis. Given the debated association of papillary thyroid carcinoma with Hashimoto's thyroiditis, it is possible that p63 expression may be a potential pathobiologic link between the two disorders. The finding of p63 in benign squamoid nests supports a possible interrelationship between these structures and both Hashimoto's thyroiditis and papillary carcinoma. The high percentage of papillary carcinomas with p63-positive foci appears to distinguish papillary carcinoma from other neoplasms originating in the thyroid.

Transoral fusion with internal fixation in a displaced hangman's fracture

STUDY DESIGN

A case is reported in which late displacement of a "hangman's fracture" was managed by transoral C2-C3 fusion by using bicortical iliac crest graft and a titanium cervical locking plate.

OBJECTIVES

To review the management of unstable fractures of the axis and to study other reports of transoral instrumentation of the cervical spine.

SUMMARY OF BACKGROUND DATA

Undisplaced fractures of the axis are considered to be stable injuries. Although late displacement is unusual, it can lead to fracture nonunion with persisting instability and spinal cord dysfunction. In this situation, an anterior fusion of the second and third cervical vertebrae is preferred to a posterior fusion from the atlas to the third cervical vertebra, which would abolish lateral rotation between C1 and C2.

METHODS

The literature on hangman's fractures was reviewed. Clinical and radiographic details of a case of C2 instability were recorded, and the particular problems posed by late displacement were considered.

RESULTS

There are no other reports of transoral instrumentation of the cervical spine. A sound fusion of C2-C3 was obtained without infection or other complications. Good neck movement returned by 6 months after surgery.

CONCLUSION

Undisplaced fractures of the axis are not always stable. The transoral route allows good access for stabilization of displaced hangman's fractures. In special circumstances, a locking plate may prove useful in securing the bone graft. The cervical spine locking plate can be inserted transorally with no complications and by using standard instrumentation.

High photorefractive sensitivity at 860 nm in reduced rhodium-doped KNbO(3)

We show that high-temperature reduction in a CO-CO(2) atmosphere increases the photorefractive sensitivity of KNbO(3):Rh at 860nm by 4 orders of magnitude compared with that of the as-grown crystal. The effective trap density is increased by a factor of 3, and the photoconductivity by a factor of 30, and the photorefractive response at a grating spacing of 0.15 mu;m is accelerated by a factor of 400. The grating buildup time at a grating spacing of 0.7 microm and an intensity of 1Wcm(-2) is 0.5 s, a value comparable with that of as-grown KNbO(3):Fe at visible wavelengths. The optical and photorefractive parameters of Rh-doped KNbO(3) subjected to reduction treatment are characterized for wavelengths of 0.48-1.064 microm .

Respiratory compliance during sedation, anesthesia, and paralysis in infants and young children

Although total respiratory compliance (Crs) has been shown to fall in adults on induction of halothane anesthesia, no successful paired studies have been reported in children. The multiple occlusion technique was used to measure Crs in 17 infants and young children during sedated sleep (CrsS) and shortly after, following induction of halothane anesthesia (CrsA). Crs fell in all but one infant after induction of anesthesia, with a mean fall of 34.7% (range 0-58%). This was accompanied by a reduction in tidal volume and increase in frequency in every case. In 7 of the 17 children, who were to be paralyzed for surgical purposes, Crs was also measured in this anesthetized-paralyzed state. When tidal volume administered during manual ventilation was similar to that observed during measurement of CrsA, Crs during this low-volume ventilation was similar to CrsA. When tidal volume was increased and Crs remeasured, there was a significant increase in every case, with the high-volume Crs within 10% of CrsS in all but one child, in whom there was a 31.4% increase with respect to CrsS. Changes in tidal volume accounted for approximately 50% of the variability in each state. These results demonstrate a highly significant fall in Crs in infants and young children after induction of halothane anesthesia. In addition it appears that this reduction in Crs can be reversed by paralyzing the child and manually ventilating with tidal volumes approximating those seen during sedation.

Perioperative complications following the use of vancomycin in children: a report of two cases

We describe two patients in whom rapid administration of vancomycin caused severe hypotension. Possible mechanisms for this effect are discussed, with reference to the role of the anaesthetist as administrator of drugs prescribed by others. Recommendations are made on safe administration of vancomycin with respect to rate of infusion and possible interactions.