On the Connection Between Geometry and Statically Determined Membrane Stresses in the Human Cornea.

Under the action of the intraocular pressure (IOP), the human cornea is stressed and deforms acquiring a quasi-spherical configuration. If the stressed configuration is known, and the cornea is regarded as a membrane, disregarding flexural behaviors with an equilibrium analysis only is possible to estimate the distribution of the average stress across the thickness. In the cornea, the action of the intraocular pressure is supported by collagen fibrils, immersed into an elastin-proteoglycan matrix, and organized in a very precise architecture to provide the necessary confinement and transparency to the light. With the goal of understanding the static consequences of shape modifications due to pathological dilatation (ectasia), we present a simplified stress analysis of the human cornea modeled as a membrane. A numerical investigation over 40 patient-specific corneas (20 normal and 20 ectatic) is carried out to establish a relationship between the physiological geometry and the distribution of the membrane stresses, and to assess the possibility to obtain information on the stress state based on topographic images only. Comparative analyses reveal that, with respect to normal corneas, in ectatic corneas the pattern of the principal stress lines is modified markedly showing a deviation from the hypothetical dominant orientation of the collagen fibrils. The rotation of the principal stress with respect to the fibril orientation can be thought as responsible of the transmission of a large amount of shear stresses onto the elastin-proteoglycan matrix. The anomalous loading of the matrix could be correlated to the evolution of time-dependent shape modifications leading to ectasia.

Multicentre registry of brain-injured patients with disorder of consciousness: rationale and preliminary data.

Diagnostic accuracy and reliable estimation of clinical evolution are challenging issues in the management of patients with disorders of consciousness (DoC). Longitudinal systematic investigations conducted in large cohorts of patients with DoC could make it possible to identify reliable diagnostic and prognostic markers. On the basis of this consideration, we devised a multicentre prospective registry for patients with DoC admitted to ten intensive rehabilitation units. The registry collects homogeneous and detailed data on patients' demographic and clinical features, neurophysiological and neuroimaging findings, and medical and surgical complications. Here we present the rationale and the design of the registry and the preliminary results obtained in 53 patients with DoC (vegetative state or minimally conscious state) enrolled during the first seven months of the study. Data at 6-month post-injury follow-up were available for 46 of them. This registry could be an important tool for collecting high-quality data through the application of rigorous methods, and it could be used in the routine management of patients with DoC admitted to rehabilitation settings.

A new simplified methodology for studying the coupled fluid-structure interaction in a weakened basilar artery.

In this paper, we study the fluid-structure interaction in a weakened basilar artery. The aim is to study how the wall shear stress changes in space and time because of the weakening, because spatial and temporal changes are thought to be possible causes of aneurysm and vascular deseases. The arterial wall, in its natural configuration, is modeled as a hyperelastic cylinder, inhomogeneous along its axis, in order to simulate the axis-symmetric weakening. The fluid is studied exploiting a recent approach for quasi-one-dimensional flows in slowly varying ducts, which allows to write the averaged equations of mass and energy balance on the basis of the velocity profile in a straight duct. The unknowns are the wall pressure, the average velocity, and the wall radial displacement. The problem is solved in two parts: first, the stationary non-linear coupled problem is solved, and an intermediate configuration is obtained. Then, we study the variation of the basic unknowns about the intermediate configuration, considering time dependence over the cardiac cycles. The results suggest that, with a 10% reduction of the main elastic modulus, the shear stress in the weakened zone changes its sign and doubles the maximum stress value detected in the healthy zone. Copyright © 2015 John Wiley & Sons, Ltd.

Prevalence of occupational voice disorders in teachers.

INTRODUCTION: In Italy the number of teachers among private and public schools is around one million. Voice disorders are thought to be one of the major occupational hazards of school teaching; in fact the teachers often use their voice with high-intensity, in noisy classes, for a long time and without suitable breaks. The aim of the study was to assess the prevalence of voice problems in teachers of Naples district, identifying risk factors for developing voice pathology. METHODS: In this study we evaluated 504 teachers (322 F-182 M) with an age ranging between 24 and 62 years, randomly choiced in 28 schools of the district of Naples submitted to a questionnaire to determine the prevalence of voice disorders. In our study we have also introduced a comparison group of not-teachers workers of 402 subjects (244 F-158 M); they were in the same age range as the teacher sample (range: 22-65 years). The control group was also submitted to a questionnaire regarding sociodemographic characteristics, smoking and alcohol use, a self-report of voice problems, voice symptoms, frequency of acute and chronic voice problems, absenteeism due to voice problems. RESULTS: The prevalence of reporting a current voice problem was significantly greater in teachers compared with not-teachers (8.7% vs 2.9%), as the prevalence of voice disorders during their lifetime too (51.4% vs 25.9%), chi2 = 86.672, p < 0.001. Women, compared with men had a higher lifetime prevalence of voice disorders. An other important data evidenced, is that 116 workers of the teachers group (23.01%) have been forced, during their professional activity, to miss job for problems related to voice; only 22 subjects of control group (5.47%) instead, missed job for voice troubles. DISCUSSION AND CONCLUSIONS: This study confirms that teachers have a higher rate of self-reported voice problems than subjects working in other occupations. Teachers, compared with not-teachers, were significantly more likely to have experienced multiple voice symptoms including hoarseness, discomfort while using their voice, difficulty projecting their voice and tiring or change in voice quality after short use. Large proportion of these problems may be preventable and prevention programs need to be developed and evaluated. Italian teachers do not receive any preventive voice training; that, in combination with poor hygienic work conditions, could increase health problems. Thus, voice training of teachers and teacher college students in some cases should be considered as a useful tool to prevent voice disorders.

The first case of osteoma in the false vocal fold.

OBJECTIVES: This article reports the first evidence of a larynx osteoma of the false vocal fold. STUDY DESIGN: Case report and literature review. METHODS: Case report and review of previously published cases of larynx osteomas. RESULTS: A 79-year-old patient was referred to our institution for dysphagia and hoarseness. Fibrolaryngoscopy showed a regular surface tumefaction of the false fold and the left ventricle, with preserved cordal motility. Patient underwent direct laryngoscopy with CO(2) laser excision of the lesion. Pathologic examination of the lesion (1.6cmx1cm) showed features consistent with an osteoma. Complete regression of symptoms was observed after surgery, with no lesions found on routine 1-year follow-up. CONCLUSIONS: Osteomas are benign, slow growing tumors of the craniofacial bone area, very rarely located in the larynx. Although the etiology is unknown, accepted theories point to embryologic, post-traumatic and infectious causes. Surgical excision is indicated only in symptomatic cases. This case report is the fourth evidence of laryngeal osteoma and, to our knowledge, the first finding of a false vocal fold osteoma.

Epidemiological study on vocal disorders in paediatric age.

Few studies analyzed the diffusion of vocal alterations especially in childhood. Aim of our study was to quantify the numbers of subjects, in paediatric age, in which dysphonia was diagnosed in our department of Phoniatrics, during a period of 5 years, (January 2002-December 2006), and also to evaluate the influence of some potential risk factors. In the considered period it emerged that the diagnosis of dysphonia was made in 312 children (17.2% of the patients affected from dysphonia), aged between 2 and 16-years-old, with a major prevalence amongst males (57%) than females (43%). On the contrary in the adult population the prevalence was: 23% in males and 77% in females. In paediatric population, the most affected range of age is the one between 8 and 14, in both male and female gender (59.6%). In 82.4% of the cases there were vocal fold lesions. The 90.3% of children with vocal fold alterations presented lesions secondary to vocal abuse and misuse and classifiable as functional dysphonia. The proportion of functional dysphonia in our sample was 92%. The 65% of children belonged to large families with more than two children, and the 30% had a family history of dysphonia (brothers, parents). The study of the behavioural characteristics has shown aggressive and hyperactive attitudes in 83% of the cases. Since in the ethiopathogenesis of the childhood dysphonia the tendency to vocal abuse has a predominant role, it would be useful to encourage the diffusion of programmes of information to show the risks linked to this abuse in children, in order to prevent the development of dysphonia in paediatric age.

Diagnostic accuracy of chemical-shift MR imaging to differentiate between adrenal adenomas and non adenoma adrenal lesions.

PURPOSE: The objective of this study was to evaluate the diagnostic accuracy of chemical-shift (CS) magnetic resonance (MR) imaging in the differential diagnosis of adenoma and nonadenoma adrenal masses. MATERIALS AND METHODS: We enrolled 36 patients (9 men, 27 women, mean age 51.3+14.4 years) with unilateral (n=31) or bilateral (n=5) adrenal masses incidentally discovered during imaging examinations [ultrasound (US), computed tomography (CT)] performed for other indications. A total of 41 adrenal lesions were evaluated (mean diameter 3.0+2.2 cm). Histology (n=19), biopsy (n=3) or clinical-imaging follow-up (n=19) demonstrated 29 adenomas, five pheochromocytomas, three cysts and four carcinomas. MR imaging was performed using the following breath-hold sequences: T1-fast field echo (FFE) [repetition time (TR)/echo time (TE)=236/4.6 ms], T2-turbo spin echo-single shot (TSE-SSh) (TR/TE=831/80 ms), T1-DUAL-FFE (TR=236, double TE=4.6/2.3 ms in phase and out of phase) and T1-FFE after gadolinium-DTPA (Gd). Axial and coronal imaging planes were used, with a slice thickness of 3-5 mm. MR images were qualitatively assessed for signal intensity of the adrenal mass relative to the liver on T1, T2, CS and T1-Gd scans; diagnostic criteria for adenomas were isointensity or hypointensity on both T1 and T2 scans, out-of-phase CS signal loss and mild transient enhancement after Gd. RESULTS: Analysis of T1-T2 signal intensity showed diagnostic accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 80%, 72%, 100%, 100% and 60%, respectively. In contrast, analysis of CS and T1-Gd signal intensity showed diagnostic accuracy, sensitivity, specificity, PPV and NPV for both sequences of 93%, 90% (p<0.05 vs. T1-T2 analysis), 100%, 100% and 80% (p<0.05 vs. T1-T2 analysis), respectively. CONCLUSIONS: CS MR imaging significantly improves characterization of adrenal masses compared with conventional T1-T2-weighted images, providing accuracy similar to that of the T1 sequence after Gd. Therefore, the CS sequence is strongly recommended for MR study of adrenal masses, and its use might obviate the need for Gd administration.

Anisotropic constitutive equations and experimental tensile behavior of brain tissue.

The present study deals with the experimental analysis and mechanical modeling of tensile behavior of brain soft tissue. A transversely isotropic hyperelastic model recently proposed by Meaney (2003) is adopted and mathematically studied under uniaxial loading conditions. Material parameter estimates are obtained through tensile tests on porcine brain materials accounting for regional and directional differences. Attention is focused on the short-term response. An extrapolation of tensile test data to the compression range is performed theoretically, to study the effect of the heterogeneity in the tensile/compressive response on the material parameters. Experimental and numerical results highlight the sensitivity of the adopted model to the test direction.

Shape of the canine diaphragm.

In an earlier study (Angelillo M, Boriek AM, Rodarte JR, and Wilson TA. J Appl Physiol 83: 1486-1491, 1997), we proposed a mathematical theory for the structure and shape of the diaphragm. Muscle bundles were assumed to lie on lines that are simultaneously geodesics and lines of principal curvature of the diaphragm surface, and the class of surfaces that are formed by line elements that are both geodesics and lines of principal curvature was described. Here we present data on the shape of the canine diaphragm that were obtained by the radiopaque marker technique, and we describe a surface that fits the data and satisfies the requirements of the theory. The costal and crural diaphragms are fit by cyclides with radii of 3.7 and 2.3 cm, respectively. In addition, the theory is extended to include the description of a joint between cyclides, and the observed properties of the joint between the costal and crural diaphragms at the dorsal end of the costal diaphragm match those required by the theory.

Muscle kinematics for minimal work of breathing.

A mathematical model was analyzed to obtain a quantitative and testable representation of the long-standing hypothesis that the respiratory muscles drive the chest wall along the trajectory for which the work of breathing is minimal. The respiratory system was modeled as a linear elastic system that can be expanded either by pressure applied at the airway opening (passive inflation) or by active forces in respiratory muscles (active inflation). The work of active expansion was calculated, and the distribution of muscle forces that produces a given lung expansion with minimal work was computed. The calculated expression for muscle force is complicated, but the corresponding kinematics of muscle shortening is simple: active inspiratory muscles shorten more during active inflation than during passive inflation, and the ratio of active to passive shortening is the same for all active muscles. In addition, the ratio of the minimal work done by respiratory muscles during active inflation to work required for passive inflation is the same as the ratio of active to passive muscle shortening. The minimal-work hypothesis was tested by measurement of the passive and active shortening of the internal intercostal muscles in the parasternal region of two interspaces in five supine anesthetized dogs. Fractional changes in muscle length were measured by sonomicrometry during passive inflation, during quiet breathing, and during forceful inspiratory efforts against a closed airway. Active muscle shortening during quiet breathing was, on average, 70% greater than passive shortening, but it was only weakly correlated with passive shortening. Active shortening inferred from the data for more forceful inspiratory efforts was approximately 40% greater than passive shortening and was highly correlated with passive shortening. These data support the hypothesis that, during forceful inspiratory efforts, muscle activation is coordinated so as to expand the chest wall with minimal work.

Theory of diaphragm structure and shape.

The muscle bundles of the diaphragm form a curved sheet that extends from the chest wall to the central tendon. Each muscle bundle exerts a force in the direction of its curvature; the magnitude of this force is proportional to the curvature of the bundle. The contribution of this force to transdiaphragmatic pressure is maximal if the direction of bundle curvature is orthogonal to the surface and the curvature is maximal. That is, the contribution of muscle tension to transdiaphragmatic pressure is maximal if the muscle bundles lie along lines that are both geodesics and lines of maximal principal curvature of the surface. A theory of diaphragm shape is developed from the assumption that all muscle bundles have these optimal properties. The class of surfaces that are formed of line elements that are both geodescis and lines of principal curvature is described. This class is restricted. The lines that form the surface must lie in planes, and all lines must have the same shape. In addition, the orientation of the lines is restricted. An example of this class that is similar to the shape of the canine diaphragm is described, and the stress distribution in this example is analyzed.

Experimental autoallergic sialadenitis in the LEW rat. I. Parameters of disease induction.

Experimental autoallergic sialadenitis (EAS) is an autoimmune mononuclear cell infiltration of the submandibular salivary gland that results in tissue destruction and glandular dysfunction. A previous report has described an animal model of induced EAS in LEW rats following sensitization with allogeneic WF submandibular gland (SMG). The present study extends this observation to an EAS disease model induced following sensitization of LEW rats with syngeneic LEW SMG. Furthermore, we describe the characterization of the mononuclear cells in the glandular infiltrates, evaluate the production of autoantibodies, and establish the parameters important for reproducible induction of EAS. Our results demonstrate that EAS can be induced in a completely syngeneic system and the histopathology of disease induction in the syngeneic and allogeneic model systems is similar. Helper/inducer (CD4+) and suppressor/cytotoxic (CD8+) T-cell subsets are the dominant cell types in the salivary mononuclear cell infiltrate. An anti-duct autoantibody was found in the serum of virtually all LEW rats with EAS. Although closely associated with disease development, the presence of this antibody was not a prerequisite for development of histopathologic disease. Induction of disease in both the syngeneic and allogeneic models of EAS is dependent upon administration of Bordetella pertussis at the time of sensitization. Finally, the histopathology of the cellular infiltrates in both the allogeneic and syngeneic models of EAS resemble those observed in the salivary tissues of Sjögren's patients. While there are several differences between EAS in the LEW rat and the full expression of Sjögren's syndrome, EAS may serve as a model to study the salivary gland component of this complex human disease.

Experimental autoallergic sialadenitis in the LEW rat. III. Role of CD4+ T cells in EAS induction.

Experimental autoallergic sialadenitis (EAS) in the LEW rat is an induced autoimmune disease of the salivary tissues. EAS is characterized by a lymphocytic infiltration that consists of both CD4+ (helper/inducer T-cell subset) and CD8+ (cytotoxic/suppressor T-cell subset) T cells and results in the immune-mediated destruction of the exocrine salivary glands. To investigate the role that each of the T-cell subsets may have in the pathogenesis of EAS, LEW rats sensitized with WF SMG homogenate were injected with monoclonal antibodies to deplete or inactivate, in vivo, the CD4, CD5 (OX19; pan T lymphocyte), CD8, or RT6 (70% of peripheral T cells) T-cell populations. Treatment with the OX8 (CD8), OX19 (CD5), or W3/25 (CD4) only partially reduced in vivo the respective splenic or lymph node T-cell subsets when analyzed on Day 14, while treatment with DS4.23 (anti-RT6) resulted in greater than 95% depletion of RT6+ spleen and lymph node T cells. EAS incidence and severity was significantly reduced in the W3/25 (CD4) treatment group (11% incidence rate; histologic score 1.0) as compared to medium-injected controls (88% incidence rate; histologic score 2.9). Although the incidence and severity of EAS in the OX19 (71%; histologic score 1.7), OX8 (55%; histologic score 1.7), and RT6 (67%; histologic score 1.6) treatment groups appeared decreased, the reduction was not statistically significant. These results provide evidence that CD4+ T cells have an important role in EAS induction and demonstrate that in vivo treatment with anti-CD4 can ameliorate and/or prevent EAS in the LEW rat.

Volume and emptying of the gallbladder in patients with cystic fibrosis.

As in cystic fibrosis (CF), gallbladder (GB) hypokinesia might play a role in the high incidence of either cholelithiasis or atrophic and hypoplastic GBs. We studied the contractility of the GB by ultrasonography (US) in 57 CF patients and in 25 age- and sex-matched healthy controls. We evaluated the status of the GB, the GB volume after an overnight fasting and 30 min after the ingestion of a standardized milk meal, the GB contractility (the percentage of reduction, (%R) of the GB volume after a meal), the presence of gallstones, and finally, the span of the liver. In addition, liver function test results were evaluated in the CF group. We concluded that the mean values of GB contractility in CF patients do not differ from those of healthy controls, the most hypokinetic GBs (%R less than 40%) being observed, however, only in the CF group. Gallstones occur in CF patients with a greater frequency than seen in the normal population, even in early childhood. The CF patients' GB mean volumes in fasting conditions are significantly greater than in healthy controls (13.5 +/- 2 versus 8.5 +/- 1.5 cc, p less than 0.0001).

Absence of RT6+ T cells in diabetes-prone biobreeding/Worcester rats is due to genetic and cell developmental defects.

Diabetes-prone BB/Wor (DP) rats lack the RT6+ peripheral T cell subset whereas diabetes-resistant BB/Wor rats have normal numbers of RT6+ T cells. Lymphocyte transfusion experiments and in vivo depletion studies have demonstrated that RT6+ T cells have an important regulatory role in the pathogenesis of insulin-dependent diabetes mellitus in BB/Wor rats. In the present study, the results of genetic complementation studies indicate that the DP rat contains an intact RT6 gene, but fails to express the RT6.1 alloantigen in the functional absence of an accessory factor (provided by RT6+ cells). At the cellular level, irradiation chimeras demonstrate that the absence of RT6+ T cells in DP rats is due to an intrinsic defect that results in abnormal development and/or differentiation of prothymocytes into RT6+ T cells. The inability of DP prothymocytes to generate RT6+ T cells is not due to serum autoantibodies, lack of accessory cells, or to the presence of inhibitory cells. Inasmuch as DP bone marrow can transfer the susceptibility for diabetes to irradiated recipients, our present results suggest that an important predisposing factor for insulin-dependent diabetes mellitus in DP rats is the inability of DP prothymocytes to generate RT6+ T cells.

Ultrasound diagnosis of Achilles tendon pathology in runners.

The great upsurge in popularity of running activities has increased the number of athletes presenting with pathology of the Achilles tendon. A clinical and ultrasonic study was performed on 47 middle and long distance runners referred to the Authors with such problems. The results of this study can be grouped as follows: 1. paratendonitis: enlargement of the antero-posterior diameter of the tendon, and hyperechogenicity of Kager's triangle; 2. tendonitis (with or without paratendonitis): thickening of the tendon, with the presence of degenerative nodules; 3. enthesopathy: thickening of the distal part of the tendon, enlargement of the hypoechogenic area behind the tendon itself and microcalcification.

Depletion of RT6.1+ T lymphocytes induces diabetes in resistant biobreeding/Worcester (BB/W) rats.

To investigate the role of RT6+ T cells in the pathogenesis of diabetes in BB/W rats, we treated animals from the diabetes-resistant (DR) subline with anti-RT6.1 lymphocytotoxic mAb. This depleted greater than 95% of peripheral RT6+ T cells but did not substantially reduce levels of circulating T cells or the in vitro response of spleen cells to mitogen. Treatment of 30-d-old DR BB/W rats in this way: induced insulitis and diabetes, rendered nondiabetic RT6-depleted DR rats susceptible to the adoptive transfer of diabetes by spleen cells from acutely diabetic BB/W rats, and yielded DR spleen cell populations capable of the adoptive transfer of diabetes to diabetes-prone (DP) or DR recipients. Treatment of DR rats beginning at 60 d of age failed to produce these effects. These results suggest that both susceptibility and resistance to diabetes in the BB/W rat are in part regulated by the RT6+ T cell subset and provide evidence for the importance of regulatory T lymphocytes in the pathogenesis of autoimmunity and diabetes in BB/W rats.