Pediatric gastroesophageal reflux and laryngopharyngeal reflux

Pediatric gastroesophageal reflux (GER) and laryngopharyngeal reflux (LPR) have gained better recognition over the past few years. GER and LPR usually present as regurgitation, emesis, epigastric pain, failure to thrive, esophagitis, or stricture. Many patients suffer respiratory disorders associated with reflux. Classification of reflux, pathophysiology, manifestations of reflux, diagnosis, and management of the disease are discussed in this article.

Airway abnormalities in patients with Arnold-Chiari malformation

OBJECTIVES

The goal was to determine the incidence and types of airway abnormalities in patients with Arnold-Chiari malformation (ACM).

METHODS

The study was a retrospective chart review of 24 patients with ACM who were evaluated and treated between November 1991 and August 1997.

RESULTS

Eighteen (75%) and 6 (25%) of the 24 patients had types I and II ACM, respectively. Three (12.5% of 24 patients) of the type II ACM patients had vocal cord impairment: 1 bilateral paralysis, 1 bilateral paresis, and 1 unilateral paralysis. None of the type I ACM patients had vocal cord impairment. Tracheotomy was necessary in 3 of the 24 patients and all in patients with type II ACM. Central sleep apnea was found in 5 of 6 type II ACM patients, but not in any of the type I ACM patients.

CONCLUSIONS

Vocal cord impairment and sleep apnea were found in 12. 5% and 21%, respectively, of this ACM population. When type II ACM patients were considered separately, the incidences of vocal cord impairment and sleep apnea were 50% and 83%, respectively. Type II ACM patients tend to have a higher incidence of airway abnormalities and other neurologic dysfunctions. Flexible fiberoptic laryngoscopy is recommended in the airway evaluation of ACM patients. Early recognition, diagnosis, and management of these abnormalities may be lifesaving.

Glycoprotein Ibalpha can mediate endothelial cell migration on von Willebrand factor-containing substrata

We have previously shown that, in addition to the vitronectin receptor (VNR, alpha(v)beta(3)), the GP Ib complex can participate in endothelial cell (EC) attachment to von Willebrand Factor (vWF) (D. A. Beacham, M. S. Cruz, and R. I. Handin, 1995, Thromb. Haemostas. 73, 309-317; D. A. Beacham, L.-P. Tran, and S. S. Shapiro, 1997, Blood 89, 4071-4077). In this study we have investigated the functional roles of these vWF receptors in the migration of untreated and TNFalpha-treated EC on vWF, a mixture of vWF and type I collagen, and on vitronectin (VN). In agreement with previous studies (D. I. Leavesley, M. A. Schwartz, M. Rosenfeld, and D. A. Cheresh, 1993, J. Cell Biol. 121, 163-170), the migration of untreated and TNFalpha-treated EC on VN was dependent entirely on the VNR. Migration of untreated EC on vWF was inhibited 10-15% by recombinant vWF-A1, the GP Ibalpha-binding domain on vWF which abrogates the platelet GP Ibalpha-vWF interaction. In contrast, migration of TNFalpha-treated EC on vWF was inhibited 50-60% by vWF-A1 or the anti-GP Ibalpha mAb AS-7 but only 20% by the anti-VNR mAb LM609. On a mixed vWF-collagen substratum, vWF-A1 inhibited untreated EC migration by 45%, and TNFalpha-treated EC migration by 75%. The possible role of EC proliferation was eliminated, since hydroxyurea completely inhibited EC proliferation without reducing migration significantly. The anti-GP Ibalpha mAb Ib1 inhibited EC migration by 50%, but reduced proliferation by only 15%. Taken together, our data demonstrate that EC migration on vWF-containing substrata involves the GP Ib complex as well as the VNR and raises the possibility that the VNR and GP Ib act cooperatively in supporting EC migration.

Cytokine treatment of endothelial cells increases glycoprotein Ib alpha-dependent adhesion to von Willebrand factor

Endothelial cells (EC) possess at least two membrane receptors for von Willebrand factor (vWF), the vitronectin receptor (VNR, alpha(v)beta3), which recognizes an Arg-Gly-Asp (RGD) sequence in the C-terminus of vWF, and glycoprotein Ib alpha (GP Ib alpha), which interacts with a region in the N-terminal A1 domain of vWF. In the absence of added cytokines, EC attachment to a vWF substratum is mediated largely through the alpha(v)beta3, with a smaller contribution by GP Ib alpha. In the present study, we have examined the effect of cytokines on the receptor specificity of EC attachment to wild-type vWF (WT-vWF) and to vWF, which had been mutated in the C-terminal RGDS sequence (RADS-vWF). Exposure of human umbilical vein EC (HUVEC) to tumor necrosis factor-alpha (TNF-alpha) or to TNF-alpha in combination with interferon-gamma (IFN-gamma), but not to interleukin-1beta (IL-1), increased attachment to RADS-vWF by about twofold. The TNF-alpha-induced increase in EC attachment was accompanied by an increase in cell surface GP Ib alpha expression; GP Ib alpha surface expression was not increased by IL-1. Attachment of untreated HUVEC to WT-vWF could be inhibited 60% to 70% by a monoclonal antibody (MoAb) (LM609) to the VNR and 30% to 40% by the A1 fragment of vWF (containing the GP Ib alpha binding domain). The pattern of inhibition of attachment to WT-vWF was largely unchanged after TNF-alpha treatment of HUVEC. In contrast, the attachment to WT-vWF of HUVEC, treated with TNF-alpha +IFN-gamma was completely inhibited by vWF-A1 and inhibited only 35% by the anti-VNR antibody LM609. Two MoAbs to GP Ib alpha produced similar, but incomplete, inhibition. Pretreatment of HUVEC with the combination of TNF-alpha + IFN-gamma produced a dramatic decrease in VNR expression, confirming previous findings of Defilippi et al. These results suggest that in the presence of the inflammatory cytokines TNF-alpha + IFN-gamma, the endothelial GP Ib complex is a major determinant of HUVEC adhesion to surface-bound vWF.

Benign lesions of the external auditory canal

Benign mass lesions of the external auditory canal, such as exostoses and osteomas, are common findings on physical examination but most often do not require treatment. The differential diagnosis of lesions in the external auditory canal, however, should not be limited to those benign processes discussed here, but should also include infectious, dermatologic, congenital, and malignant processes.

Familial multiple glomus tumors: report of a pedigree and literature review

Glomus tumors are uncommon, benign soft tissue tumors that can occur in a familial or sporadic pattern. Only 15 pedigrees have been reported to date. We report a family with three generations developing multiple glomus tumors of the skin. Although controversy exists over pattern of inheritance, review of the published pedigrees plus this additional one suggests an autosomal dominant inheritance with incomplete penetrance and variable expressivity.

Regional distribution of M1, M2 and non-M1, non-M2 subtypes of muscarinic binding sites in rat brain

The distribution of subtypes of the muscarinic receptor in homogenates of the rat brain was investigated by measuring the competitive inhibition of the binding [3H]N-methylscopolamine by pirenzepine and AF-DX 116 (11[[2-[(diethylamino)methyl]-1-piperidinyl]acetyl]-5, 11-dihydro-6H-pyrido[2,3-b][1,4]benzodiazepine-6-one). In most brain regions, the competitive binding curves for AF-DX 116 and pirenzepine were consistent with a two-site model. The dissociation constant of pirenzepine for its high-affinity site (M1 receptor) was approximately 10(-8) M, whereas the dissociation constant of AF-DX 116 for its high affinity site (M2 receptor) was approximately 10(-7) M. In many regions, particularly those in the forebrain, the sum of the densities of the M1 and M2 binding sites was substantially less than 100% of the total sites, indicating the existence of a third population of sites lacking high affinity for both pirenzepine and AF-DX 116. We have designated these latter sites as non-M1, non-M2 muscarinic receptors. In general, the densities of the M1 and non-M1, non-M2 binding sites were highest in cerebral cortex, corpus striatum and hippocampus, intermediate in thalamus and hypothalamus, and lowest in midbrain, medulla-pons and cerebellum, whereas the M2 binding site had a relatively low, uniform density throughout the brain. The binding capacity of [3H]N-methylquinuclidinyl benzilate was estimated to be 20 to 30% lower than that of [3H]quinuclidinyl benzilate in various regions of the forebrain, but not in more caudal regions of the brain where the two radioligands had approximately the same binding capacities. Treatment of homogenates of the cerebral cortex with benzilylcholine mustard caused a selective loss of the majority of the [3H]N-methylscopolamine binding sites but spared 25% of the sites labeled by [3H]quinuclidinyl benzilate The results of pirenzepine/[3H]quinuclinyl benzilate competitive binding experiments on cerebral cortex treated with benzilylcholine mustard showed that the residual binding sites for [3H] quinuclidinyl benzilate were enriched in M1 muscarinic receptors.