Characterization of heterozygous and homozygous mouse models with the most common hypertrophic cardiomyopathy mutation MYBPC3c.2373InsG in the Netherlands

Hypertrophic cardiomyopathy (HCM) is frequently caused by mutations in the cardiac myosin binding protein-C (cMyBP-C) encoding gene MYBPC3. In the Netherlands, approximately 25% of patients carry the MYBPC3c.2373InsG founder mutation. Most patients are heterozygous (MYBPC3+/InsG) and have highly variable phenotypic expression, whereas homozygous (MYBPC3InsG/InsG) patients have severe HCM at a young age. To improve understanding of disease progression and genotype-phenotype relationship based on the hallmarks of human HCM, we characterized mice with CRISPR/Cas9-induced heterozygous and homozygous mutations. At 18-28 weeks of age, we assessed the cardiac phenotype of Mybpc3+/InsG and Mybpc3InsG/InsG mice with echocardiography, and performed histological analyses. Cytoskeletal proteins and cardiomyocyte contractility of 3-4 week old and 18-28 week old Mybpc3c.2373InsG mice were compared to wild-type (WT) mice. Expectedly, knock-in of Mybpc3c.2373InsG resulted in the absence of cMyBP-C and our 18-28 week old homozygous Mybpc3c.2373InsG model developed cardiac hypertrophy and severe left ventricular systolic and diastolic dysfunction, whereas HCM was not evident in Mybpc3+/InsG mice. Mybpc3InsG/InsG cardiomyocytes also presented with slowed contraction-relaxation kinetics, to a greater extent in 18-28 week old mice, partially due to increased levels of detyrosinated tubulin and desmin, and reduced cardiac troponin I (cTnI) phosphorylation. Impaired cardiomyocyte contraction-relaxation kinetics were successfully normalized in 18-28 week old Mybpc3InsG/InsG cardiomyocytes by combining detyrosination inhibitor parthenolide and β-adrenergic receptor agonist isoproterenol. Both the 3-4 week old and 18-28 week old Mybpc3InsG/InsG models recapitulate HCM, with a severe phenotype present in the 18-28 week old model.

EGFR/IGF1R Signaling Modulates Relaxation in Hypertrophic Cardiomyopathy

BACKGROUND

Diastolic dysfunction is central to diseases such as heart failure with preserved ejection fraction and hypertrophic cardiomyopathy (HCM). However, therapies that improve cardiac relaxation are scarce, partly due to a limited understanding of modulators of cardiomyocyte relaxation. We hypothesized that cardiac relaxation is regulated by multiple unidentified proteins and that dysregulation of kinases contributes to impaired relaxation in patients with HCM.

METHODS

We optimized and increased the throughput of unloaded shortening measurements and screened a kinase inhibitor library in isolated adult cardiomyocytes from wild-type mice. One hundred fifty-seven kinase inhibitors were screened. To assess which kinases are dysregulated in patients with HCM and could contribute to impaired relaxation, we performed a tyrosine and global phosphoproteomics screen and integrative inferred kinase activity analysis using HCM patient myocardium. Identified hits from these 2 data sets were validated in cardiomyocytes from a homozygous MYBPC3c.2373insG HCM mouse model.

RESULTS

Screening of 157 kinase inhibitors in wild-type (N=33) cardiomyocytes (n=24 563) resulted in the identification of 17 positive inotropes and 21 positive lusitropes, almost all of them novel. The positive lusitropes formed 3 clusters: cell cycle, EGFR (epidermal growth factor receptor)/IGF1R (insulin-like growth factor 1 receptor), and a small Akt (α-serine/threonine protein kinase) signaling cluster. By performing phosphoproteomic profiling of HCM patient myocardium (N=24 HCM and N=8 donors), we demonstrated increased activation of 6 of 8 proteins from the EGFR/IGFR1 cluster in HCM. We validated compounds from this cluster in mouse HCM (N=12) cardiomyocytes (n=2023). Three compounds from this cluster were able to improve relaxation in HCM cardiomyocytes.

CONCLUSIONS

We showed the feasibility of screening for functional modulators of cardiomyocyte relaxation and contraction, parameters that we observed to be modulated by kinases involved in EGFR/IGF1R, Akt, cell cycle signaling, and FoxO (forkhead box class O) signaling, respectively. Integrating the screening data with phosphoproteomics analysis in HCM patient tissue indicated that inhibition of EGFR/IGF1R signaling is a promising target for treating impaired relaxation in HCM.

Real-Time Measurements of Calcium and Contractility Parameters in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) represent a powerful tool for studying mutation-mediated changes in cardiomyocyte function and defining the effects of stressors and drug interventions. In this study, it is demonstrated that this optics-based system is a powerful tool to assess the functional parameters of hiPSC-CMs in 2D. By using this platform, it is possible to perform paired measurements in a well-preserved temperature environment on different plate layouts. Moreover, this system provides researchers with instant data analysis. This paper describes a method for measuring the contractility of unmodified hiPSC-CMs. Contraction kinetics are measured at 37 °C based on pixel correlation changes relative to a reference frame taken at relaxation at a 250 Hz sampling frequency. Additionally, simultaneous measurements of intracellular calcium transients can be acquired by loading the cell with a calcium-sensitive fluorophore, such as Fura-2. Using a hyperswitch, ratiometric calcium measurements can be performed on a 50 µm diameter illumination spot, corresponding to the area of the contractility measurements.

Automatic detection of adult cardiomyocyte for high throughput measurements of calcium and contractility

Simultaneous calcium and contractility measurements on isolated adult cardiomyocytes have been the gold standard for the last decades to study cardiac (patho)physiology. However, the throughput of this system is low which limits the number of compounds that can be tested per animal. We developed instrumentation and software that can automatically find adult cardiomyocytes. Cells are detected based on the cell boundary using a Sobel-filter to find the edge information in the field of view. Separately, we detected motion by calculating the variance of intensity for each pixel in the frame through time. Additionally, it detects the best region for calcium and contractility measurements. A sensitivity of 0.66 ± 0.08 and a precision of 0.82 ± 0.03 was reached using our cell finding algorithm. The percentage of cells that were found and had good contractility measurements was 90 ± 10%. In addition, the average time between 2 cardiomyocyte calcium and contractility measurements decreased from 93.5 ± 80.2 to 15.6 ± 8.0 seconds using our software and microscope. This drastically increases throughput and provides a higher statistical reliability when performing adult cardiomyocyte functional experiments.

Muscle weakness in a S. pneumoniae sepsis mouse model

Background

The pathophysiology of intensive care unit-acquired weakness (ICU-AW), which affects peripheral nerves, limb muscles and respiratory muscles, is complex and incompletely understood. This illustrates the need for an ICU-AW animal model. However, a translatable and easily applicable ICU-AW animal model does not exist. The objective of this study was to investigate whether induction of a S. pneumoniae sepsis could serve as a model for ICU-AW.

Methods

A total of 24 C57BL/6J mice were infected intranasally with viable S. pneumoniae. Control mice (n=8) received intranasal saline and mice of the blank group (n=4) were not inoculated. Ceftriaxone was administered at 24 h (n=8) or at 48h after inoculation (n=8), or as soon as mice lost 10% of their body weight (n=8). The primary endpoint, in vivo grip strength, was measured daily. At the end of the experiment, at 120 h after inoculation, electrophysiological recordings were performed and diaphragm muscle was excised to determine ex vivo muscle fiber strength and myosin/action ratio.

Results

Grip strength over time was similar between experimental and control groups and electrophysiological recordings did not show signs of ICU-AW. Diaphragm fiber contractility measurements showed reduced strength in the group that received ceftriaxone at 48 h after S. pneumoniae inoculation.

Conclusions

Ex vivo diaphragm weakness, but no in vivo limb weakness was found in the S. pneumoniae mouse model in which severe illness was induced. This does not reflect the full clinical picture of ICU-AW as seen in humans and as such this model did not fulfill our predefined requirements. However, this model may be used to study inflammation induced diaphragmatic weakness.

Proteomics and microscopy tools for the study of antimicrobial resistance and germination mechanisms of bacterial spores

Bacterial spores are ubiquitous in nature and can withstand both chemical and physical stresses. Spores can survive food preservation processes and upon outgrowth cause food spoilage as well as safety risks. The heterogeneous germination and outgrowth behavior of isogenic spore populations exacerbates this risk. A major unknown factor of spores is likely to be the inherently heterogeneous spore protein composition. The proteomics methods discussed here help in broadening the knowledge about spore structure and identification of putative target proteins from spores of different spore formers. Approaches to synchronize Bacillus subtilis spore formation, and to analyze spore proteins as well as the physiology of spore germination and outgrowth are also discussed. Live-imaging and fluorescence microscopy techniques discussed here allow analysis, at single cell level, of the 'germinosome', the process of spore germination itself, spore outgrowth and the spore intracellular pH dynamics. For the latter, a recently published improved pHluorin (IpHluorin) under control of the ptsG promoter is applicable. While the data obtained from such tools offers novel insight in the mechanisms of bacterial spore awakening, it may also be used to probe candidate antimicrobial compounds for inhibitory effects on spore germination and strengthen microbial risk assessment.

Developmental trajectories of structural and pragmatic language skills in school-aged children with Williams syndrome

BACKGROUND

This study aimed to compare developmental courses of structural and pragmatic language skills in school-aged children with Williams syndrome (WS) and children with idiopathic intellectual disability (IID). Comparison of these language trajectories could highlight syndrome-specific developmental features.

METHOD

Twelve monolingual Dutch-speaking children with WS aged 5.10 to 13.3 years were assessed by means of standardised structural language tests measuring receptive and expressive vocabulary and sentence comprehension and production. Pragmatic language was evaluated by means of an expressive referential communication task and a retelling test. All of these language abilities were re-evaluated with the same measures after a period of 18 to 24 months. Performance was compared to 12 children with IID pairwise matched for chronological age (CA) and non-verbal fluid reasoning (Gf) at Time 1. Non-verbal mental age (NVMA) was taken into account when delineating developmental trajectories.

RESULTS

Children with WS outperformed children with IID on expressive vocabulary development. In contrast, sentence comprehension was significantly poorer than in children with IID at the second time point. Increased variability and rather poor performance on pragmatic language tasks were demonstrated in the WS group. Irrelevant and off-topic extraneous information transfer continued to be a syndrome-specific characteristic of children with WS.

CONCLUSION

The data provide new insights into diverging developmental trajectories across language domains. Expressive structural language skills tend to progress more rapidly than receptive language skills in children with WS causing more distinctive language profiles over time. Some children with WS seem to benefit from the growth in expressive structural language abilities to enhance their expressive pragmatic language skills, while in some others these abilities remain challenging. This study highlights the need for continued follow-up of language challenges in WS and for a dynamic and individualised interventional approach.

Reduced force of diaphragm muscle fibers in patients with chronic thromboembolic pulmonary hypertension

Patients with pulmonary hypertension (PH) suffer from inspiratory muscle weakness. However, the pathophysiology of inspiratory muscle dysfunction in PH is unknown. We hypothesized that weakness of the diaphragm, the main inspiratory muscle, is an important contributor to inspiratory muscle dysfunction in PH patients. Our objective was to combine ex vivo diaphragm muscle fiber contractility measurements with measures of in vivo inspiratory muscle function in chronic thromboembolic pulmonary hypertension (CTEPH) patients. To assess diaphragm muscle contractility, function was studied in vivo by maximum inspiratory pressure (MIP) and ex vivo in diaphragm biopsies of the same CTEPH patients (N = 13) obtained during pulmonary endarterectomy. Patients undergoing elective lung surgery served as controls (N = 15). Muscle fiber cross-sectional area (CSA) was determined in cryosections and contractility in permeabilized muscle fibers. Diaphragm muscle fiber CSA was not significantly different between control and CTEPH patients in both slow-twitch and fast-twitch fibers. Maximal force-generating capacity was significantly lower in slow-twitch muscle fibers of CTEPH patients, whereas no difference was observed in fast-twitch muscle fibers. The maximal force of diaphragm muscle fibers correlated significantly with MIP. The calcium sensitivity of force generation was significantly reduced in fast-twitch muscle fibers of CTEPH patients, resulting in a ∼40% reduction of submaximal force generation. The fast skeletal troponin activator CK-2066260 (5 μM) restored submaximal force generation to levels exceeding those observed in control subjects. In conclusion, diaphragm muscle fiber contractility is hampered in CTEPH patients and contributes to the reduced function of the inspiratory muscles in CTEPH patients.

Intravenous iron therapy in patients with idiopathic pulmonary arterial hypertension and iron deficiency

In patients with idiopathic pulmonary arterial hypertension (iPAH), iron deficiency is common and has been associated with reduced exercise capacity and worse survival. Previous studies have shown beneficial effects of intravenous iron administration. In this study, we investigated the use of intravenous iron therapy in iron-deficient iPAH patients in terms of safety and effects on exercise capacity, and we studied whether altered exercise capacity resulted from changes in right ventricular (RV) function and skeletal muscle oxygen handling. Fifteen patients with iPAH and iron deficiency were included. Patients underwent a 6-minute walk test, cardiopulmonary exercise tests, cardiac magnetic resonance imaging, and a quadriceps muscle biopsy and completed a quality-of-life questionnaire before and 12 weeks after receiving a high dose of intravenous iron. The primary end point, 6-minute walk distance, was not significantly changed after 12 weeks (409 ± 110 m before vs. 428 ± 94 m after; P = 0.07). Secondary end points showed that intravenous iron administration was well tolerated and increased body iron stores in all patients. In addition, exercise endurance time (P < 0.001) and aerobic capacity (P < 0.001) increased significantly after iron therapy. This coincided with improved oxygen handling in quadriceps muscle cells, although cardiac function at rest and maximal [Formula: see text] were unchanged. Furthermore, iron treatment was associated with improved quality of life (P < 0.05). In conclusion, intravenous iron therapy in iron-deficient iPAH patients improves exercise endurance capacity. This could not be explained by improved RV function; however, increased quadriceps muscle oxygen handling may play a role. (

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT01288651).

Diaphragm muscle fiber weakness and ubiquitin-proteasome activation in critically ill patients

RATIONALE

The clinical significance of diaphragm weakness in critically ill patients is evident: it prolongs ventilator dependency, and increases morbidity and duration of hospital stay. To date, the nature of diaphragm weakness and its underlying pathophysiologic mechanisms are poorly understood.

OBJECTIVES

We hypothesized that diaphragm muscle fibers of mechanically ventilated critically ill patients display atrophy and contractile weakness, and that the ubiquitin-proteasome pathway is activated in the diaphragm.

METHODS

We obtained diaphragm muscle biopsies from 22 critically ill patients who received mechanical ventilation before surgery and compared these with biopsies obtained from patients during thoracic surgery for resection of a suspected early lung malignancy (control subjects). In a proof-of-concept study in a muscle-specific ring finger protein-1 (MuRF-1) knockout mouse model, we evaluated the role of the ubiquitin-proteasome pathway in the development of contractile weakness during mechanical ventilation.

MEASUREMENTS AND MAIN RESULTS

Both slow- and fast-twitch diaphragm muscle fibers of critically ill patients had approximately 25% smaller cross-sectional area, and had contractile force reduced by half or more. Markers of the ubiquitin-proteasome pathway were significantly up-regulated in the diaphragm of critically ill patients. Finally, MuRF-1 knockout mice were protected against the development of diaphragm contractile weakness during mechanical ventilation.

CONCLUSIONS

These findings show that diaphragm muscle fibers of critically ill patients display atrophy and severe contractile weakness, and in the diaphragm of critically ill patients the ubiquitin-proteasome pathway is activated. This study provides rationale for the development of treatment strategies that target the contractility of diaphragm fibers to facilitate weaning.

The striated muscles in pulmonary arterial hypertension: adaptations beyond the right ventricle

Pulmonary arterial hypertension (PAH) is a fatal lung disease characterised by progressive remodelling of the small pulmonary vessels. The daily-life activities of patients with PAH are severely limited by exertional fatigue and dyspnoea. Typically, these symptoms have been explained by right heart failure. However, an increasing number of studies reveal that the impact of the PAH reaches further than the pulmonary circulation. Striated muscles other than the right ventricle are affected in PAH, such as the left ventricle, the diaphragm and peripheral skeletal muscles. Alterations in these striated muscles are associated with exercise intolerance and reduced quality of life. In this Back to Basics article on striated muscle function in PAH, we provide insight into the pathophysiological mechanisms causing muscle dysfunction in PAH and discuss potential new therapeutic strategies to restore muscle dysfunction.

Contractile dysfunction of left ventricular cardiomyocytes in patients with pulmonary arterial hypertension

BACKGROUND

After lung transplantation, increased left ventricular (LV) filling can lead to LV failure, increasing the risk of post-operative complications and mortality. LV dysfunction in pulmonary arterial hypertension (PAH) is characterized by a reduced LV ejection fraction and impaired diastolic function.

OBJECTIVES

The pathophysiology of LV dysfunction in PAH is incompletely understood. This study sought to assess the contribution of atrophy and contractility of cardiomyocytes to LV dysfunction in PAH patients.

METHODS

LV function was assessed by cardiac magnetic resonance imaging. In addition, LV biopsies were obtained in 9 PAH patients and 10 donors. The cross-sectional area (CSA) and force-generating capacity of isolated single cardiomyocytes was investigated.

RESULTS

Magnetic resonance imaging analysis revealed a significant reduction in LV ejection fraction in PAH patients, indicating a reduction in LV contractility. The CSA of LV cardiomyocytes of PAH patients was significantly reduced (~30%), indicating LV cardiomyocyte atrophy. The maximal force-generating capacity, normalized to cardiomyocyte CSA, was significantly reduced (~25%). Also, a reduction in the number of available myosin-based cross-bridges was found to cause the contractile weakness of cardiomyocytes. This finding was supported by protein analyses, which showed an ~30% reduction in the myosin/actin ratio in cardiomyocytes from PAH patients. Finally, the phosphorylation level of sarcomeric proteins was reduced in PAH patients, which was accompanied by increased calcium sensitivity of force generation.

CONCLUSIONS

The contractile function and the CSA of LV cardiomyocytes is substantially reduced in PAH patients. We propose that these changes contribute to the reduced in vivo contractility of the LV in PAH patients.

Diaphragm weakness in pulmonary arterial hypertension: role of sarcomeric dysfunction

We previously demonstrated that diaphragm muscle weakness is present in experimental pulmonary arterial hypertension (PH). However, the nature of this diaphragm weakness is still unknown. Therefore, the aim of this study was to investigate whether changes at the sarcomeric level contribute to diaphragm weakness in PH. For this purpose, in control rats and rats with monocrotaline-induced PH, contractile performance and myosin heavy chain content of demembranated single diaphragm fibers were determined. We observed a reduced maximal tension of 20% (P < 0.05), whereas tension cost was preserved in type 2X and 2B diaphragm fibers in PH compared with control. The reduced maximal tension was associated with a reduction of force generated per half-sarcomeric myosin heavy chain content. Additionally, reduced Ca(2+) sensitivity of force generation was found in type 2X fibers compared with control, which could exacerbate diaphragm muscle weakness at submaximal activation. No changes in maximal tension and Ca(2+) sensitivity of force generation were observed in fibers from the nonrespiratory extensor digitorum longus muscle. Together, these findings indicate that diaphragm weakness in PH is at least partly caused by sarcomeric dysfunction, which appears to be specific for the diaphragm.

The effects of deformation, ischemia, and reperfusion on the development of muscle damage during prolonged loading

Deep tissue injury (DTI) is a severe form of pressure ulcer where tissue damage starts in deep tissues underneath intact skin. In the present study, the contributions of deformation, ischemia, and reperfusion to skeletal muscle damage development were examined in a rat model during a 6-h period. Magnetic resonance imaging (MRI) was used to study perfusion (contrast-enhanced MRI) and tissue integrity (T2-weighted MRI). The levels of tissue deformation were estimated using finite element models. Complete ischemia caused a gradual homogeneous increase in T2 (∼20% during the 6-h period). The effect of reperfusion on T2 was highly variable, depending on the anatomical location. In experiments involving deformation, inevitably associated with partial ischemia, a variable T2 increase (17–66% during the 6-h period) was observed reflecting the significant variation in deformation (with two-dimensional strain energies of 0.60–1.51 J/mm) and ischemia (50.8–99.8% of the leg) between experiments. These results imply that deformation, ischemia, and reperfusion all contribute to the damage process during prolonged loading, although their importance varies with time. The critical deformation threshold and period of ischemia that cause muscle damage will certainly vary between individuals. These variations are related to intrinsic factors, such as pathological state, which partly explain the individual susceptibility to the development of DTI and highlight the need for regular assessments of individual subjects.

Ischemia-reperfusion injury in rat skeletal muscle assessed with T2-weighted and dynamic contrast-enhanced MRI

Pressure ulcers are localized areas of soft tissue breakdown due to mechanical loading. Susceptible individuals are subjected to pressure relief strategies to prevent long loading periods. Therefore, ischemia-reperfusion injury may play an important role in the etiology of pressure ulcers. To investigate the inter-relation between postischemic perfusion and changes in skeletal muscle integrity, the hindlimbs of Brown Norway rats were subjected to 4-h ischemia followed by 2-h reperfusion. Dynamic contrast-enhanced MRI was used to examine perfusion, and changes in skeletal muscle integrity were monitored with T2-weighted MRI. The dynamic contrast-enhanced MRI data showed a heterogeneous postischemic profile in the hindlimb, consisting of areas with increased contrast enhancement (14-76% of the hindlimb) and regions with no-reflow (5-77%). For T2, a gradual increase in the complete leg was observed during the 4-h ischemic period (from 34 to 41 msec). During the reperfusion phase, a heterogeneous distribution of T2 was observed. Areas with increased contrast enhancement were associated with a decrease in T2 (to 38 msec) toward preischemic levels, whereas no-reflow areas exhibited a further increase in T2 (to 42 msec). These results show that reperfusion after prolonged ischemia may not be complete, thereby continuing the ischemic condition and aggravating tissue damage.

Evaluation of quality of life in people with aphasia using a Dutch version of the SAQOL-39

PURPOSE

To examine the quality of life (QoL) of people with aphasia and to study the influence of variables such as age, time post onset and (degree of) social support on the QoL of aphasic persons.

METHOD

We compared the scores of an aphasic population (N = 43) with those of a healthy control group (N = 43) and of a group of patients with brain lesions without neurogenic communication disorders (N = 43) on a Dutch version of the Stroke and Aphasia Quality of Life-scale (SAQoL-39) and on a social support questionnaire. In half of the aphasic group, the SAQoL-39 was re-administered 8 months after the first testing.

RESULTS

People with aphasia obtained significantly lower scores for QoL measures compared with both other groups. Especially, communicative and psychosocial factors seem to influence these results. Older people with aphasia scored lower than younger persons and women tend to evaluate their QoL somewhat more negatively than men. Persons who had aphasia for more than 6 months tended to have higher QoL-scores compared with those who had become aphasic more recently. After 8 months, the retested group scored significantly higher on communication and on psychosocial functioning than on first testing.

CONCLUSIONS

Gathering information on QoL after suffering from stroke and from aphasia can lead to a better understanding of the problems involved. The clinical use of instruments such as the SAQoL-39 can probably contribute to a more patient oriented rehabilitation, whereby the focus not only lie in improving linguistic skills but also on reducing the impairments and the handicaps that accompany aphasia and thus on increasing QoL.

SISL (ScreeningsInstrument Schisis Leuven): assessment of cleft palate speech, resonance and myofunction

This paper presents an assessment protocol for the evaluation and description of speech, resonance and myofunctional characteristics commonly associated with cleft palate and/or velopharyngeal dysfunction. The protocol is partly based on the GOS.SP.ASS'98 and adapted to Flemish. It focuses on the relevant aspects of cleft type speech necessary to facilitate assessment, adequate diagnosis and management planning in a multi-disciplinary setting of cleft team care.

A potential link between oral status and hearing impairment: preliminary observations

Some previous studies suggest an association between tooth loss and hearing loss. The aim of this study is to assess the relation between oral status and hearing acuity. Forty-eight patients (mean age: 64.7 years) were allocated to four groups: one was wearing complete dentures in both jaws, another had shortened dental arches, a third had full dental arches in both jaws and the last lacked any occlusal stops (i.e. no occlusal vertical dimension, because of the absence of teeth or occlusal pairs). Audiological testing was performed in a noise-free chamber. Air and bone conduction were checked at different frequencies and the air-bone gap was determined. After correction for age and gender, a difference in air and bone conduction because of the oral status was found for low and for high frequencies while no significant differences were (P < 0.05) found for the air-bone gap. The number of teeth, number of occluding tooth pairs and presence or lack of occlusal vertical dimension, was significantly related to the gradient of hearing loss (P < 0.05). The discrepancy in hearing loss between complete denture wearers and patients without any occlusal vertical dimension, strengthens the hypothesis that it is the lack of the latter that is associated with hearing loss. At what level hearing loss occurs, needs further investigation.

The influence of oral implant-supported prostheses on articulation and myofunction

The aim of the present research was to assess articulation and myofunction in patients wearing fixed or removable prostheses supported by oral implants. 164 edentulous patients with implant supported prostheses were divided in four subgroups, dependent on their dental status, and compared to control groups of forty five subjects having a natural dentition. More than fifteen articulatory and myofunctional parameters were evaluated. The results showed that subjects with prostheses on implants tend to have more articulation problems than controls. Especially patients with a complete fixed prosthesis on implants in the upper jaw seemed to experience problems pronouncing /s/ and /z/. There also seemed to be influences of age and hearing factors.

The effect of vagal nerve stimulation on voice

OBJECTIVE

Vagal nerve stimulation therapy through implanted vagal nerve stimulators is an accepted therapy for refractory seizure disorders. One significant side effect of vagal nerve stimulation is voice change. This study evaluates the impact that these voice changes have on patients' lives, and the physiological effects that vagal nerve stimulation has on the larynx.

METHODS

Patients were selected from the pool of patients at Rush-Presbyterian-St. Luke's Medical Center who underwent implantation of vagal nerve stimulator devices. Three methods were used to evaluate the impact the devices had on patients and on their vocal cords. First, a questionnaire was sent to the patients to ascertain the degree of vocal and social impairment that occurs as a result of the implant. Second, videostroboscopy was used to analyze the effect that vagal nerve stimulation had on the larynx. Third, computerized voice analysis objectively analyzed the patients' voices both during and in between vagal nerve stimulations.

RESULTS

Although patients noted significant voice changes during stimulation of the implant, the impairment is well tolerated and less debilitating than the underlying seizure disorder. Hyperstimulation of the affected vocal cord was observed during vagal stimulation with paramedian positioning, vocal fold tensing, and loss of mucosal wave. Increase in jitter and shimmer was consistent.

CONCLUSION

Vagal nerve implantation devices create significant but well-tolerated vocal side effects. Investigation of these devices increases our understanding of laryngeal physiology and may give insight into future laryngeal pacing. Preimplantation laryngeal examination should be performed routinely to rule out laryngeal pathology that could lead to significant complications.

Evaluation of speech in patients rehabilitated with various oral implant-supported prostheses

In the present study, speech function was assessed in edentulous patients wearing fixed or removable dental prostheses supported or not by oral implants. A total of 138 patients participated in the present research. The experimental group (n=113) was divided in 4 subgroups. Subgroup FD/FFPi comprised 22 patients with a maxillary full denture (=FD) and a mandibular fixed full prosthesis on implants (=FFPi). Subgroup FFPi/ND consisted of 27 patients with a maxillary fixed full prosthesis on implants and a natural dentition (=ND) in the mandible. Subgroup FD/ODi included 49 patients wearing a maxillary full denture and a mandibular overdenture on 2 implants (=ODi). Subgroup FFPi/FFPi comprised 15 patients having a fixed full prosthesis on implants in both jaws. The outcome of the logopedic screening of the experimental group was compared with that of a control group of subjects having a natural dentition (ND/ND; n=25). A standard clinical procedure for evaluation of speech was carried out by a speech pathologist. Besides, specific oral and prosthetic parameters were scored in all patients. It was established that one or more pronunciation difficulties occurred in 84% of the patients of the experimental group. This was significantly more than in the control group, where half the number of subjects had some speech deficiencies. No clear influence of specific oral and prosthetic parameters could be identified. From the present results, it could be concluded that in patients rehabilitated with oral implant-supported prostheses speech disorder is more frequently observed than in subjects with a natural dentition.

Prognostic significance of Bcl-2 and p53 expression in advanced laryngeal squamous cell carcinoma

BACKGROUND

Proteins regulating the cell cycle and cell death are frequently abnormally expressed in cancer. Several of these, particularly p53 and Bcl-2, have been widely suggested as possible prognostic markers in diverse human malignancies. Their role in predicting outcome in squamous cell carcinomas of the head and neck is unclear and may depend on the location, stage, and treatment of the tumor.

METHODS

To assess this question specifically for advanced squamous cell carcinoma of the larynx, we studied 69 patients with stage III or IV tumors, all but 6 of whom were treated with surgery plus postoperative irradiation by a single physician. We studied the patients retrospectively to test the association between expression of Bcl-2 and p53, as assessed by immunohistochemistry, with treatment outcome and survival.

RESULTS

Twenty of the 69 patients died from their tumor (poor outcome); the rest were alive and tumor free at the last follow-up or died of unrelated causes without clinical tumor recurrence (good outcome). Fourteen tumors had detectable Bcl-2 expression, including 8 scored as overexpressors. Thirty-nine tumors overexpressed p53. Expression of neither Bcl-2 nor p53 was associated with outcome, overall survival, or disease-free survival. Only tumor stage was significantly associated with outcome and disease-free survival.

CONCLUSION

These data indicate that assessing expression of p53 or Bcl-2 is unlikely to be prognostically useful for surgically treated advanced laryngeal carcinoma.

Neuropeptides, nitric oxide synthase and GAP-43 in B4-binding and RT97 immunoreactive primary sensory neurons: normal distribution pattern and changes after peripheral nerve transection and aging

We have here sought to cross-correlate the expression of immunoreactivities for several neuropeptides, nitric oxide synthase (NOS) and the growth associated protein GAP-43 in subpopulations of dorsal root ganglion (DRG) neurons tagged by the selective markers isolectin B4 and the neurofilament antibody RT97, selective for, respectively, subpopulations of small and large DRG neurons. By use of double- and triple-labeling immunohistochemistry, non-manipulated and sciatic nerve transected young adult rats as well as aged (30-months-old) rats were examined using a confocal microscope equipped with enhanced spectral separation. In young adult rats, the DRG neuron profiles could be divided into three subpopulations (B4 binding (B4+) approximately 50%; RT97-immunoreactive (RT97+) approximately 35%; B4-/RT97- approximately 15%). Calcitonin gene-related peptide (CGRP) is expressed in all three subpopulations. Galanin message-associated peptide (GMAP) colocalize with CGRP (100%) but is not expressed in RT97+ profiles. NOS is present in the RT97- subpopulations and frequently colocalize with CGRP (92%). GAP-43 is expressed in all three DRG subpopulations and colocalize with CGRP (88%), GMAP (38%) and/or NOS (22%). Only very small differences were seen among the young adult rats, implicating that the size of respective subpopulation as well as the expression pattern for neuropeptides, NOS and GAP-43 are fairly stable. Sciatic nerve transection reduced B4-binding but not RT97-like immunoreactivity. Distinct changes in the expression of neuropeptides, NOS and GAP-43 were evident in the DRG subpopulations and, furthermore, the regulatory changes were very similar among the lesioned animals. The relative size of the DRG subpopulations was unaffected by aging, while the expression of neuropeptides was altered showing similarities with the changes induced by axotomy in young adult rats.

Improved nerve regeneration with neutralization of transforming growth factor-beta1

OBJECTIVES

Recovery of injured peripheral nerves depends on a balance between Schwann cell regeneration and scar formation. Transforming growth factor-beta1 (TGF-beta1) has been implicated as a humoral stimulus in scar formation. The neutralization of TGF-beta1 has been beneficial in the reduction of fibrosis. This study was to identify the presence of TGF-beta1 in regenerating peripheral nerve and to measure motor nerve regeneration by the neutralization of TGF-beta1 in neural wounds.

STUDY DESIGN

A randomized study of rat sciatic nerve regeneration.

METHOD

Sciatic nerve axotomy was performed, followed by serial immunohistochemical staining by anti-TGF-beta1 at 12 to 216 hours (n = 5). Two groups (n = 10) with sciatic axotomy and epineural repair were treated with a 7-day perineural administration of neutralizing antibody of TGF-beta1 or saline carrier via subcutaneous silicone infusion port. A control group (n = 10) without axotomy with anti-TGF-beta1 administration was established. At 12 weeks the compound muscle action potential amplitude (CMAP) and the muscle twitch strength generated by the gastrocnemiussoleus muscle complex were measured.

RESULTS

TGF-beta1 was qualitatively present with maximal concentration by 72 to 144 hours. CMAP amplitude in the anti-TGF-beta1/axotomy group was 49.6% of the control and the axotomy/saline group was 31% of the control. Muscle twitch strength was 74% and 46.5%, respectively. These differences were statistically significant, P = .05.

CONCLUSIONS

The presence of TGF-beta1 at regenerating nerve sites was confirmed. The benefit of neutralization of transforming growth factor on CMAP and muscle twitch strength was shown. These results suggest improved regeneration at nerve injury sites with neutralization of TGF-beta1.

[Use of tissue expanders on the scalp]

Tissue expanders have emerged recently as a new option for the treatment of alopecia. The method consists in expanding the scalp beyond the defective area. In this way, some disadvantages like the alterations in the donor area and low density of hair follicles, that may result from other techniques, are avoided. We present our experience with tissue expanders in the treatment of 32 patients with alopecia. The extent of these areas varied from 30 to 150 cm2, and the causes were: burn sequels in 12 patients; trauma sequels in ten; tumoral resections in ten; giant nevus pilosus in four and baldness (male standard) in two patients. The resection of the area with alopecia and the replacement by normal adjacent tissue was possible without any complications in all cases. However some disadvantages were observed. They included the necessity for a second surgical procedure because of marked deformity of the cephalic segment.

On-line sorting of human chromosomes by centromeric index, and identification of sorted populations by GTG-banding and fluorescent in situ hybridization

Using slit-scan flow cytometry, the shape of human metaphase chromosomes, as expressed in their centromeric index (CI), and the DNA content of the chromosomes have been used as parameters in bivariate flow karyotyping. The resolution of the DNA vs CI flow karyogram of the larger chromosomes up to chromosome 13 is much higher than the resolution obtained in the DNA-based monovariate flow karyogram. Chromosome length appears to be an important factor in the resolution of the DNA vs CI-based flow karyogram. A method has been developed to obtain chromosomes in suspension that are long enough for adequate analysis. Several chromosomes that cannot be distinguished or are difficult to discriminate in the DNA-based karyogram can now be distinguished as individual peaks, e.g., chromosomes 1 and 2. The peak of chromosomes 9-12 can be separated into two peaks formed by chromosomes 9 and 11, and 10 and 12, respectively. The advantage of the system applied in this study is that the DNA vs CI analysis is performed on-line, allowing chromosomes to be sorted on the bases of their CI. Pulse shapes of the selected chromosomes can be recorded simultaneously with the transmission of the sorting command. The purity of the sorted fraction can be estimated from the off-line inspection of these pulse shapes. Fractions of chromosome 1 have been sorted out on the basis of the CI information, centrifuged on slides, fixed and subsequently banded with trypsin and Giemsa or hybridized with the chromosome 1 specific probe, pUC 1.77. The observed purity under the selected conditions ranges from 80%-99% and is in accordance with the estimates of the purities made on the basis of the simultaneously recorded pulse shapes. Fixation of the chromosome suspension prior to flow cytometric analysis and sorting appears to be essential for the preservation of their morphology and has no adverse influence on the resolution of Giemsa banding or on the quality of in situ hybridization.

Marked heterogeneity of aromatase activity in human malignant melanoma tissue

The prognosis from human malignant melanoma varies according to sex and to multiple histologic, biologic and cell kinetic parameters. Thus melanomas exhibit a major degree of heterogeneity in their biologic properties and further characterization of their biochemical heterogeneity should yield important information. The present study sought to demonstrate the activity of a biochemical marker of estrogen synthesis, the aromatase enzyme, in melanoma tissue and to determine its range of activity. Initially, we validated a highly sensitive radiometric assay for aromatase by comparing it with a direct product isolation method. We detected production of 417 pmol/g protein/h of estrone and 37.3 pmol/g protein/h of estradiol by direct product isolation in a human melanoma and 398 pmol estrone/g protein/h by the radiometric assay. The activity present was blocked by similar amounts of the aromatase inhibitor, aminoglutethimide, as were necessary to block placental, breast cancer, and rat brain aromatase activity. We then assayed aromatase radiometrically in 19 human melanomas and found measurable activity ranging from 9 to 398 pmol estrone/g protein/h in 15 tissues. No relationship with the patient's age or sex was demonstrated. The activity exceeded by 2-fold that previously detected in 49/61 human breast cancers. This study identified a marker enzyme in melanoma tissue which varied by 40-fold among human tumors. Correlation of aromatase activity with prognosis and response to various types of therapy is now necessary to establish the biologic relevance of this finding.

Growth of cavernous hemangioma with puberty

There is a clinical impression among physicians that puberty may prompt growth of hemangiomas. We observed significant growth of a large cavernous hemangioma in a patient at the onset of puberty despite absent estrogen and progesterone receptors in the hemangioma tissue.