The muscular compliance of the auditory tube: a model-based survey

OBJECTIVES: The role of the paratubal muscles, especially the medial pterygoid muscle, still is unclear. The aim of this study was to define the function of the medial pterygoid muscle concerning the muscular compliance of the auditory tube. METHODS: High-resolution cross-sectional T1 magnetic resonance imaging data of one of the authors' paratubal structures were used, a new functional 3-D model of the auditory tube and its related structures visualized by the Hamburg VOXEL-MAN digital image system. RESULTS: Functional 3-D reconstructions of the paratubal structures reveal that the medial pterygoid muscle is acting as a movable hypomochlion of the tensor veli palatini muscle. Contraction of the medial pterygoid muscle increases and relaxation decreases the force of the tensor veli palatini muscle on the distal part of the auditory tube. Hence, the opening pressure of the auditory tube is moderated by the action of the medial pterygoid muscle. CONCLUSION: The influence of the medial pterygoid muscle on the opening pressure of the auditory tube may have an impact on the diagnosis and therapy in patients with patent auditory tube as well as the middle ear pathology in patients with cleft palate.     

Prevalence and specificity of antigastric autoantibodies in adolescents infected with Helicobacter pylori

OBJECTIVES: Antigastric autoantibodies (AGA) can be detected in as many as 50% of adults infected with Helicobacter pylori. We investigated H pylori -associated antigastric autoimmunity in children and adolescents. STUDY DESIGN: Patients with dyspepsia (n = 78; mean age 10.9 years, range 2-21 years, SE 0.46 years) underwent gastroscopy. H pylori infection was determined by serologic and histologic features and breath tests. AGA were detected by immunohistochemistry and were characterized by immunoprecipitation with the gastric hydrogen ion, potassium ion, adenosine triphosphatase (H(+),K(+)-ATPase). In absorption assays, antibodies against H pylori were removed to determine the role of molecular mimicry. RESULTS: AGA were detected in 9 (18%) of the 51 infected patients and in 1 (4 %) of the 27 noninfected patients (P =.08; nonsignificant) and could not be absorbed to H pylori. Children with AGA were significantly older (P =.01). AGA in H pylori gastritis reacted against the gastric H(+),K(+)-ATPase in 3 (33%) of the 9 patients. CONCLUSIONS: The age of the patient or the duration of gastritis seem to be relevant factors for the formation of antigastric autoimmunity. The gastric H(+),K(+)-ATPase represents an autoantigen as early as childhood. No evidence for a role of molecular mimicry between H pylori and the host at this young age could be found.     

Frataxin promotes antioxidant defense in a thiol-dependent manner resulting in diminished malignant transformation in vitro

Friedreich ataxia is an inherited disorder caused by decreased expression of frataxin protein. Increasing evidence suggests that this protein might detoxify reactive oxygen species (ROS) by an unknown mechanism. Here we demonstrate that transgenic overexpression of human frataxin increases cellular antioxidant defense via activation of glutathione peroxidase and elevation of reduced thiols, thereby reducing the incidence of malignant transformation induced by ROS, as observed by soft agar assays and tumour formation in nude mice. These findings expand the understanding of antioxidant properties of frataxin, and tentatively suggest a role in the early induction of cancer.     

Normative values and determinants of physical capacity in individuals with spinal cord injury

We reanalyzed data from five studies with similar or identical methodology performed by our laboratory to define normative values and determinants of physical capacity in individuals with tetraplegia and paraplegia. Each study consisted of a graded wheelchair exercise test to determine peak oxygen uptake and maximal power output and could additionally include a wheelchair sprint test to determine short-term (anaerobic) power output and/or an isometric strength test. The combined subject population included 166 individuals (20 women), varying considerably for age, body mass, lesion level, time since injury, and activity level. Ranges in physical capacity parameters were extensive and normative values for individuals with tetraplegia and paraplegia were established. These physical capacity norms could be used for evaluation of fitness status and training or therapeutic interventions. Multiple regression procedures indicated that 48-80% of the variance in physical capacity could be explained by lesion level and completeness, activity level, gender, age, body mass, and time since injury. Although physical capacity is largely determined by factors that cannot be altered, such as lesion level, age, and gender, changeable factors such as activity level and body mass play an additional role.     

Hemispheric lateralization effects of rhythm implementation during syllable repetitions: an fMRI study

Rhythm in terms of the modulation of syllable durations represents an information-bearing feature of verbal utterances contributing both to the meaning of a sentence (linguistic prosody) as well as a speaker's emotional expression (affective prosody). In order to delineate the neural structures subserving rhythmic shaping of speech production, functional magnetic resonance imaging (fMRI) was performed during (a) isochronous syllable repetitions and (b) production of syllable triplets with lengthening either of the initial or final unit. A cognitive subtraction approach (rhythmic versus isochronous iterations) revealed activation of right-sided perisylvian areas (superior temporal gyrus, Broca analogue and adjacent premotor cortex) as well as contralateral subcortical structures (putamen and thalamus). Presumably, these responses reflect a right-hemisphere rehearsal mechanism of rhythmic patterns and left-hemisphere monitoring of verbal output.     

Deletion of leucine 61 in glucose-6-phosphate dehydrogenase leads to chronic nonspherocytic anemia,granulocyte dysfunction,and increased susceptibility to infections

In this study the blood cells of 4 male patients from 2 unrelated families with chronic nonspherocytic anemia and recurrent bacterial infections were investigated. The activity of glucose-6- phosphate dehydrogenase (G6PD) in the red blood cells and in the granulocytes of these patients was below detection level. Moreover, their granulocytes displayed a decreased respiratory burst upon activation. Sequencing of genomic DNA revealed a novel 3-base pair (TCT) deletion in the G6PD gene, predicting the deletion of a leucine at position 61. The mutant G6PD protein was undetectable by Western blotting in the red blood cells and granulocytes of these patients. In phytohemagglutinin-stimulated lymphocytes the G6PD protein was present, but the amount of G6PD protein was strongly diminished in the patients' cells. Purified mutant protein from an Escherichia coli expression system showed decreased heat stability and decreased specific activity. Furthermore, we found that the messenger RNA of G6PD(180-182delTCT) is unstable, which may contribute to the severe G6PD deficiency observed in these patients. We propose the name "G6PD Amsterdam" for this new variant.