An in vitro experimental study on the relationship between pulsatile tinnitus and the dehiscence/thinness of sigmoid sinus cortical plate

Pulsatile tinnitus (PT), characterized as pulse-synchronous, is generally objective. Sigmoid sinus (SS) venous sound is widely suggested to be a possible sound source of PT. The dehiscence and thinness of SS cortical plate (CP) was commonly reported as PT pathology in previous studies, but lack quantitative or biomechanical analysis. In this study, it was aimed to quantify the relationship between venous sound and CP dehiscence/thinness using in vitro experiment. The in vitro models of SS and CP were established based on 3D-printing, with the developed pulsatile venous flow in the SS model. The generated sound signal and the vibration response at the dehiscent/thinned area were analyzed. The sound signal generated in the normal-sized dehiscence model was pulse-synchronous within 100-–400 Hz, which had similar acoustic characteristics as the clinical PT sounds. It was concluded that the pulsatile venous sound is produced at TS-SS junction in case of CP dehiscence. The CP, even a thinned one can effectively diminish the venous sound and sound-generating pulsatile vibration at TS-SS junction. The CP dehiscence would induce pulse-synchronous and high pressure venous sound, as well as pulse-synchronous vibration above 20 Hz, regardless of the dehiscence size. On the contrary, the CP thinness would not induce obvious venous sound or pulsatile vibration above 20 Hz.     

A study on relationship between pulsatile tinnitus and temporal bone pneumatization grade

Pulsatile tinnitus (PT) is a common symptom in otology. In some cases, the venous flow in the sigmoid sinus (SS) is the source of PT. It is suggested that the venous sound is propagated into the tympanic cavity through the air pathway of temporal bone air cells (TBAC). The hyperpneumatization of TBAC was hypothesized as a direct pathology of PT through amplifying the venous sound, but there is no quantitative analysis. This study aims to quantify the relationship between the venous sound amplification and the pneumatization grade of TBAC. The acoustic numerical simulation and statistical analysis were performed based on the radiology data of 21 pulsatile tinnitus patients. The TBAC of these patients were classified into hypopneumatization, normal pneumatization and hyperpneumatization grades according to three standards. The in vitro acoustic experiment was done as the validation of simulation. It is indicated that the SS standard is effective for the clinical evaluation of venous sound amplification. The TBAC amplifies the venous sound due to the acoustic resonance at the first mode frequency, regardless of the pneumatization grades. The normal pneumatic TBAC exhibits the highest sound amplification effect on the venous sound amongst the three grades, contributing mostly to PT, but would not induce PT without any other causes.     

The endothelial microenvironment in the venous valvular sinus: thromboresistance trends and inter-individual variation

The valve sinuses of the deep venous system are frequent sites of venous thrombus initiation. We previously reported that, in comparison with the non-valvular lumenal endothelium, the valve sinus endothelium had decreased expression of von Willebrand factor (vWF) and increased expression of endothelial protein C receptor (EPCR) and thrombomodulin (TM), suggesting alteration in the procoagulant/anticoagulant balance. We hypothesized that increased stasis in the deeper recesses of the venous valves would be associated with a gradient of increased thromboresistance. Expression of EPCR, TM, and vWF was analyzed via quantitative confocal immunofluorescence in residual saphenous veins collected following coronary artery bypass procedures. In agreement with our hypothesis, endothelial expression of vWF in the valve sinus decreased from the uppermost to the deepest region of the valve sinus. In contrast to our hypothesis, EPCR expression decreased from the uppermost to the deepest region of the valve sinus (p < 0.001) and TM expression remained unchanged throughout the valve sinus. Comparison of the non-valvular lumenal endothelium with the valve sinus endothelium demonstrated significantly decreased vWF expression (p < 0.001) in the valvular sinus consistent with our previous report; however, we did not observe statistically significant differences in EPCR or TM expression in this comparison. In addition, remarkable inter-individual variation in expression of these three proteins was also observed. These findings suggest that the genesis of these observations is more complex than predicted by our initial hypothesis, likely due, at least in part, to the complex rheology of the valvular sinus microenvironment.     

The marginal zone and marginal sinus in the spleen of the gerbil. A light and electron microscopy study

The spleen of the adult gerbil (M. unguiculatus) is characterized by the absence of venous sinuses and ellipsoid sheaths. The follicle (white pulp) is separated from the surrounding red pulp by a distinct marginal zone. The cell types in the marginal zone are common to both the follicle and red pulp. Separating the marginal zone from the follicle is a vascular channel of capillary dimension, the marginal sinus. A number of terminal segments of the arterial vessels within the follicle were observed to form a direct connection with the marginal sinus. Ultrastructurally, discontinuities were evident within the walls of the marginal sinus that would permit passage of both cellular and plasma components from the marginal sinus to either marginal zone or the follicle.     

Range of corixid sound signals in the biotope

ABSTRACT. The propagation of sound in the frequency band (2–12 kHz) used by the Corixidae was measured in two shallow natural ponds. At distances of more than 1 m from the shore the water was at least O.4 m deep. The first pond was eutrophic and contained no plants. The spread of sound into the open water obeyed approximately the geometric attenuation of the sound pressure level (SPL); a loss of 6dB for each doubling of the distance from the point sound source. Near the shore the attenuation was considerably greater, especially for low frequencies; for a 2 kHz signal the damping of the SPL was c. 40–50 dB/m.
The second pond had dense plant growth, and the sound attenuation depended strongly on the photosynthetic activity of the waterplants. Measurements in winter, with an overcast sky, revealed only a slight damping effect of the plants for a 10kHz test signal. During intense sunlight in summer, however, in addition to the geometric attenuation the damping effect of the plants over a distance of O.5 m was 50 dB for a 2 kHz signal and 80 dB for 10 kHz. This effect was due to gas bubbles produced during intense photosynthesis.
Song A of Corixa dentipes Thms. (Heteroptera) males elicits usually a response by male conspecifics. The threshold SPL for this response was measured to be c. 40 dB lower than the SPL at a distance of O.1 m from a stridulating animal. From the measurements of sound propagation it follows, therefore, that the effective range of Song A in the most favourable case is at least 10m, though in a pond overgrown with plants it can be less than O.4 m.     

Sacral adipofascial turn-over flap for the excisional defect of pilonidal sinus.

The aim of pilonidal sinus surgery includes complete resection of the lesion and filling of the resultant soft-tissue defect by some means; this has a major influence on whether a lesion will occur after surgical treatment. The creation of a sacral adipofascial turn-over flap for the excisional defect has been performed in seven cases of pilonidal sinus since November of 1992. During the postoperative follow-up period, which ranged from 10 months to 7 years 11 months (mean duration, 5 years 2 months), partial dehiscence of the wound as a result of fatlysis was observed and treated conservatively in one case; however, primary healing was obtained in the other cases. No recurrence was seen in any of the seven cases. This procedure is not indicated in patients in whom wide skin resection is required because of the excessive tension associated with skin closure in such cases. However, the method is convenient, less invasive, and reliable, and therefore considered to be useful in the treatment of pilonidal sinus.     

Coronary sinus of the heart in various anomalies of the conotruncus

Thirty-one hearts with anomalous conotruncus (common arterial trunk, hypoplasia of the aorta with transposition, atresia of the pulmonary trunk) have been studied. There are some peculiarities in anatomy and topography of the coronary sinus, concerning its sources, that is veins forming the venous sinus, position and interrelations with the venous sulcus and with the interatrial septum, size and form of the ostium and valve of the coronary sinus. The most amount of the anatomical peculiarities of the sinus are observed in the preparations, where the anomalous conotruncus is combined with absence of one or both cardiac septa.     

A curious case of impossible coronary sinus cannulation

A 40-year-old male, diagnosed to have WPW syndrome and symptomatic with recurrent palpitations, was taken up for radiofrequency ablation. There was difficulty in coronary sinus cannulation. Coronary venogram revealed coronary sinus atresia with persistent left superior vena cava, and collateral venous pathways draining into the right atrium. This case is discussed for the rare coronary venous anomaly, its embryology and the difficulties in the management during electrophysiological studies.     

Flow patterns in the jugular veins of pulsatile tinnitus patients

Pulsatile Tinnitus (PT) is a pulse-synchronous sound heard in the absence of an external source. PT is often related to abnormal flow in vascular structures near the cochlea. One vascular territory implicated in PT is the internal jugular vein (IJV). Using computational fluid dynamics (CFD) based on patient-specific Magnetic Resonance Imaging (MRI), we investigated the flow within the IJV of seven subjects, four symptomatic and three asymptomatic of PT. We found that there were two extreme anatomic types classified by the shape and position of the jugular bulbs: elevated and rounded. PT patients had elevated jugular bulbs that led to a distinctive helical flow pattern within the proximal internal jugular vein. Asymptomatic subjects generally had rounded jugular bulbs that neatly redirected flow from the sigmoid sinus directly into the jugular vein. These two flow patterns were quantified by calculating the length-averaged streamline curvature of the flow within the proximal jugular vein: 130.3±8.1 m⁻¹ for geometries with rounded bulbs, 260.7±29.4 m⁻¹ for those with elevated bulbs (P<0.005). Our results suggest that variations in the jugular bulb geometry lead to distinct flow patterns that are linked to PT, but further investigation is needed to determine if the vortex pattern is causal to sound generation.     

A new single work bout test to estimate critical power and anaerobic work capacity

The purpose of this study was to develop a 3-minute, all-out test protocol using the Monark cycle ergometer for estimating the critical power (CP) and anaerobic work capacity (AWC) with the resistance based on body weight. Twelve moderately trained adults (mean age ± SD = 23.2 ± 3.5 years) performed an incremental cycle ergometer test to exhaustion. The CP and AWC were estimated from the original work limit (W(lim)) vs. time limit (T(lim)) relationship (CP(PT)) and a 3-minute all-out test (CP(3min)) against a fixed resistance and compared with the CP and AWC estimated from the new 3-minute tests on the Monark cycle ergometer (CP(3.5%) and CP(4.5%)). The resistance values for the CP(3.5%) and CP(4.5%) tests were set at 3.5 and 4.5% of the subject's body weight (kilograms). The results indicated that there were no significant differences (p > 0.05) among mean CP values for CP(PT) (178 ± 47 W), CP(3.5%) (173 ± 40 W), and CP(4.5%) (186 ± 44 W). The mean CP(3min) (193 ± 54 W), however, was significantly greater than CP(PT) and CP(3.5%). There were no significant differences in AWC for the CP(PT) (13,412 ± 6,247 J), CP(3min) (10,895 ± 2,923 J), and CP(4.5%) (9,842 ± 4,394 J). The AWC values for the CP(PT) and CP(3min), however, were significantly greater than CP(3.5%) (8,357 ± 2,946 J). The results of this study indicated that CP and AWC could be estimated from a single 3-minute work bout test on the Monark cycle ergometer with the resistance set at 4.5% of the body weight. A single work bout test with the resistance based on the individual's body weight provides a practical and accessible method to estimate CP and AWC.     

生长抑素通过中缝大核发挥镇痛和增强电针镇痛的作用

本工作以钾离子透入引起大鼠甩尾为痛指标,观察了中缝大核微量注射生长抑素、生长抑素的耗竭剂半胱胺和抗生长抑素血清对大鼠痛阈和电针镇痛效应的影响。中缝大核微量注射生长抑素可提高大鼠的痛阈,并使电针镇痛的效应加强。用半胱胺耗竭或用抗生长抑素血清中和中缝大核中的生长抑素,均可使大鼠的痛阈降低,并减弱电针镇痛的效应。这表明生长抑素可能通过中缝大核发挥镇痛和增强电针镇痛的作用。     

Sympathetic restraint of respiratory sinus arrhythmia: implications for vagal-cardiac tone assessment in humans

Clinicians and experimentalists routinely estimate vagal-cardiac nerve traffic from respiratory sinus arrhythmia. However, evidence suggests that sympathetic mechanisms may also modulate respiratory sinus arrhythmia. Our study examined modulation of respiratory sinus arrhythmia by sympathetic outflow. We measured R-R interval spectral power in 10 volunteers that breathed sequentially at 13 frequencies, from 15 to 3 breaths/min, before and after beta-adrenergic blockade. We fitted changes of respiratory frequency R-R interval spectral power with a damped oscillator model: frequency-dependent oscillations with a resonant frequency, generated by driving forces and modified by damping influences. beta-Adrenergic blockade enhanced respiratory sinus arrhythmia at all frequencies (at some, fourfold). The damped oscillator model fit experimental data well (39 of 40 ramps; r = 0.86 +/- 0.02). beta-Adrenergic blockade increased respiratory sinus arrhythmia by amplifying respiration-related driving forces (P < 0.05), without altering resonant frequency or damping influences. Both spectral power data and the damped oscillator model indicate that cardiac sympathetic outflow markedly reduces heart period oscillations at all frequencies. This challenges the notion that respiratory sinus arrhythmia is mediated simply by vagal-cardiac nerve activity. These results have important implications for clinical and experimental estimation of human vagal cardiac tone.     

Microcirculatory pathways in normal human spleen, demonstrated by scanning electron microscopy of corrosion casts

Confusion regarding microcirculatory pathways in normal human spleen has arisen due to extrapolation from pathological material and from other mammalian spleens, not to mention difficulties in tracing intricate three-dimensional routes from the study of thin sections or cut surfaces of tissue. We examined microcirculatory pathways in normal human spleens freshly obtained from organ transplant donors. A modified corrosion casting procedure was used to obtain an open view of vessels and their connections. Our results demonstrate: 1) "arteriolar-capillary bundles" within lymphatic nodules and extensive branching of arterioles in the marginal zone (MZ); 2) the marginal sinus around lymphatic nodules; 3) the peri-marginal cavernous sinus (PMCS) outside the MZ or immediately adjacent to the nodule itself; the PMCS receives flow via ellipsoid sheaths and MZ, or directly from arterial capillaries, and drains into venous sinuses; 4) fast pathways for flow into venous sinuses via ellipsoid sheaths; 5) arterial capillary terminations in the reticular meshwork of the red pulp or MZ ("open" circulation); direct connections to venous sinuses also occur ("closed" circulation), although rarely; and 6) numerous open-ended venous sinuses in the MZ, allowing a large proportion of the splenic inflow to bypass the red cell filtration sites in the reticular meshwork and at venous sinus walls.     

Self-selected resistance training intensity in healthy women: the influence of a personal trainer

The purpose of the present investigation was to examine the influence of resistance training with a personal trainer versus unsupervised resistance training on the self-selected intensities used by women during resistance exercise. Forty-six resistance-trained women (age = 26.6 +/- 6.4 years; body mass = 64.2 +/- 10.9 kg) who either trained individually (n = 27; No PT) or with a personal trainer (n = 19; PT) were carefully instructed to select a weight they used in their own resistance training workouts that enabled the completion of 10 repetitions for the chest press (CP), leg press (LP), seated row (SR), and leg extension (LE) exercises. Each participant was subsequently tested for one repetition-maximum (1RM) strength on each exercise, and the self-selected intensity was calculated based on a percent of each 1RM value. For self-selected relative intensity, the PT group selected significantly greater intensities for LP (50% vs. 41%), CP (57.4% vs. 48%), and SR (56% vs. 42%) whereas a trend (p = 0.10) was observed for LE (43% vs. 38%) compared with No PT. Overall, the average self-selected intensity for all exercises was approximately 51.4% in PT group and approximately 42.3% in the No PT group. 1RM values for LP, LE, and SR were greater in the PT than No PT group. Ratings of perceived exertion values were significantly greater in the PT compared with the No PT group for CP, LE, and SR but not LP. These results indicate that resistance training under the supervision of a personal trainer leads to greater initial 1RM strength values, self-selection of greater workout intensities, and greater ratings of perceived exertion values during resistance exercise.     

Simulation of coronary circulation with special regard to the venous bed and coronary sinus occlusion

The vascular beds of the left circumflex and the left anterior descending coronary arteries are modelled by means of coupled differential equations that consider an arterial, a capillary and a venous section. In a stepwise procedure, experimental data from normal coronary perfusion and coronary sinus occlusion are used to assess the model parameters. For venous distensibility, a non-linear form of pressure-volume relationship proved vital to reproduce the characteristics of the rise in venous pressure after the onset of coronary sinus occlusion. Numerical integration was carried out for normal perfusion and for coronary sinus occlusion, yielding time courses of flows, volumes and pressures within large coronary arteries, capillaries and coronary veins. Coronary sinus occlusion reduces total mean flow by 18% and divides intramyocardial flow between the capillaries and the veins into a forward component of 3.03 mls⁻¹ and a backward component of − 1.54 mls⁻¹. This result represents a prediction for a haemodynamic quantity which is therapeutically important but inacessible to measurement. Varying degrees of systolic myocardial squeezing are studied to display the impact of myocardial contractility and vessel collapse on the mean values and phasic components of intra-myocardial flows.     

Case-control study of risk of cerebral sinus thrombosis in oral contraceptive users who are carriers of hereditary prothrombotic conditions

Objective: To investigate whether users of oral contraceptives who are carriers of a hereditary prothrombotic condition (factor V Leiden mutation, protein C, S, or antithrombin deficiency) have an increased risk of cerebral sinus thrombosis. Design: Comparison of a prospective series of cases of cerebral sinus thrombosis with population data. Setting: Neurological teaching hospitals from different regions in the Netherlands (cases) and a representative sample of the non-institutionalised Dutch population (controls). Subjects: 40 women aged 18-54 years with cerebral sinus thrombosis (cases) and 2248 women aged 18-49 years (controls). Main outcome measure: Current use of oral contraceptives at the time of the thrombosis (cases) or at the time of the questionnaire (controls). Prevalences of a hereditary prothrombotic condition in patients and in the population with odds ratios. Results: 34 of 40 (85%) women with cerebral sinus thrombosis used oral contraceptives, versus 1007 of 2248 (45%) of the control women; the age adjusted odds ratio was 13 (95% confidence interval 5 to 37). Seven of 36 patients (19%) had a prothrombotic deficiency, versus 7% expected in the population; this corresponds to a threefold to fourfold increase in risk. In women who used oral contraceptives and also carried a prothrombotic defect, the odds ratio for cerebral sinus thrombosis was about 30 relative to women who had neither risk factor. Conclusion: The use of oral contraceptives and being a carrier of a hereditary prothrombotic condition increase the risk of and interact in a multiplicative way in the development of cerebral sinus thrombosis.

Key messages

• The use of oral contraceptives is associated with an increased risk of cerebral venous sinus thrombosis
• This risk of cerebral venous sinus thrombosis in women who use oral contraceptives is larger if there is an additional hereditary prothombotic factor (protein C, S, or antithrombin deficiency, factor V Leiden mutation)
• The association between oral contraceptives, thrombophilia, and deep vein thrombosis is also valid for cerebral sinus thrombosis
• Women do not need to stop using oral contraceptives as the absolute risk of cerebral sinus thrombosis is very small

     

Chemical characterization and in vitro crude protein degradability of thin stillage derived from barley- and wheat-based ethanol production

A study was conducted to characterize the different carbohydrate and protein fractions of wheat- and barley-based thin stillage samples. In vitro crude protein degradability of wheat- and barley-based thin stillage was estimated relative to soyabean (SBM) and canola (CM) meal using a protease enzyme assay. Results of the carbohydrate analysis showed that wheat thin stillage had similar neutral (NDF, average 328.5 g kg⁻¹) and lower (P < 0.05) acid detergent fibre (ADF) than barley-based thin stillage. Relative to barley-based thin stillage, wheat thin stillage had higher (P < 0.05) crude protein (CP) and soluble CP content. However, the amount of CP associated with NDF and ADF was higher (P < 0.05) in barley-based thin stillage than in wheat thin stillage. Fractionation of true protein showed that most of the CP (average 707 g kg⁻¹ of CP) was present in the slowly degradable true protein fraction and was similar in both byproducts. Glutamic acid was the main amino acid in thin stillage and was higher (P < 0.05) in wheat than in barley-based thin stillage. However, barley-based thin stillage had higher (P < 0.05) levels of lysine, methionine, arginine, threonine, leucine and isoleucine than wheat thin stillage. Results of the in vitro trial indicated that effective degradability of CP (g kg⁻¹ of CP) followed the order (P < 0.05): SBM (665.0) > wheat thin stillage (614.0) > CM (531.0) > barley-based thin stillage (493.0). It was concluded that barley-based thin stillage had different chemical characteristics than wheat thin stillage. The reduced CP degradability of barley-based thin stillage relative to wheat thin stillage was attributed to a lower CP and a higher acid detergent in soluble CP level.     

Wound ballistics of the pig mandibular angle: A preliminary finite element analysis and experimental study

To study wound ballistics of the mandibular angle, a combined hexahedral-tetrahedral finite element (FE) model of the pig mandible was developed to simulate ballistic impact. An experimental study was carried out by measuring impact load parameters from 14 fresh pig mandibles that were shot at the mandibular angle by a standard 7.62 mm M43 bullet. FE analysis was executed through the LS-DYNA code under impact loads similar to those obtained from the experimental study. The resulting residual velocity, the transferred energy from the bullet to the mandible, and the surface area of the entrance wound had no statistical differences between the FE simulation and the experimental study. However, the mean surface area of the exit wounds in the experimental study was significantly larger than that in the simulation. According to the FE analysis, the stress concentrated zones were mainly located at the region of impact, condylar neck, coronoid process and mandibular body. The simulation results also indicated that trabecular bone had less stress concentration and a lower speed of stress propagation compared with cortical bone. The FE model is appropriate and conforms to the basic principles of wound ballistics. This modeling system will be helpful for further investigations of the biomechanical mechanisms of wound ballistics.     

Transmembrane topology of human glucose 6-phosphate transporter.

Glycogen storage disease type 1b is caused by a deficiency in a glucose 6-phosphate transporter (G6PT) that translocates glucose 6-phosphate from the cytoplasm to the endoplasmic reticulum lumen where the active site of glucose 6-phosphatase is situated. Using amino- and carboxyl-terminal tagged G6PT, we demonstrate that proteolytic digestion of intact microsomes resulted in the cleavage of both tags, indicating that both termini of G6PT face the cytoplasm. This is consistent with ten and twelve transmembrane domain models for G6PT predicted by hydropathy analyses. A region of G6PT corresponding to amino acid residues 50-71, which constitute a transmembrane segment in the twelve-domain model, are situated in a 51-residue luminal loop in the ten-domain model. To determine which of these two models is correct, we generated two G6PT mutants, T53N and S55N, that created a potential Asn-linked glycosylation site at residues 53-55 (N53SS) or 55-57 (N55QS), respectively. N53SS or N55QS would be glycosylated only if it is situated in a luminal loop larger than 33 residues as predicted by the ten-domain model. Whereas wild-type G6PT is not a glycoprotein, both T53N and S55N mutants are glycosylated, strongly supporting the ten-helical model for G6PT.     

Genetic Na channelopathies and sinus node dysfunction

Voltage-gated Na⁺ channels are transmembrane proteins that produce the fast inward Na⁺ current responsible for the depolarization phase of the cardiac action potential. They play fundamental roles in the initiation, propagation, and maintenance of normal cardiac rhythm. Inherited mutations in SCN5A, the gene encoding the pore-forming α-subunit of the cardiac-type Na⁺ channel, result in a spectrum of disease entities termed Na⁺ channelopathies. These include multiple arrhythmic syndromes, such as the long QT syndrome type 3 (LQT3), Brugada syndrome (BrS), an inherited cardiac conduction defect (CCD), sudden infant death syndrome (SIDS) and sick sinus syndrome (SSS). To date, mutational analyses have revealed more than 200 distinct mutations in SCN5A, of which at least 20 mutations are associated with sinus node dysfunction including SSS. This review summarizes recent findings bearing upon: (i) the functional role of distinct voltage-gated Na⁺ currents in sino-atrial node pacemaker function; (ii) genetic Na⁺ channelopathy and its relationship to sinus node dysfunction.