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Dartos reflex: a sympathetically mediated scrotal reflex.

The dartos muscle is a sympathetically innervated dermal muscle layer within the scrotum, distinct from the somatically innervated cremasteric muscle. We electrophysiologically demonstrate the presence of a dartos reflex (DR), which can be used to evaluate the thoracolumbar sympathetic and genitofemoral nerve pathways. In 20 healthy men, we evoked the DR by cutaneous stimulation of the thigh and recorded the resultant scrotal skin contraction. We recorded hand, foot, and perineal sympathetic skin responses (SSRs) as controls. The DR was reliable and reproducible, as were the SSRs. The mean left DR latency was 4.8 s (SD, 2.7 s) and right DR latency was 5.4 s (SD, 3 .4), both of which were longer than the mean hand, foot, and perineal SSRs (P < 0.05). An intact reflex arc reflects the integrity of the afferent and efferent branches of the genitofemoral nerve (T12-L2). The DR test can also be used to assess scrotal autonomic innervation. Abnormalities of dartos innervation may impact testis thermoregulation and spermatogenesis.

Adult↗

A simply constructed system for mean blood flow measurement.

Blood flow measuring equipment and cardiac bypass pumps must be calibrated against a direct measurement of flow using timed collection. Single vessel timed collection systems have problems associated with their use. Repeated determinations of flow cannot be made rapidly, and frothing and fluid surface instability in the collecting vessel render the timing of a measured volume flow difficult and inaccurate. Collecting vessels which fill from the bottom may exert a changing back pressure on the source of flow. A semi-automated timed collection system is presented which overcomes these disadvantages. It has been used successfully to calibrate electromagnetic flowmeters and heart bypass pumps with 1% reproducibility or better. The system has also been used to measure coronary sinus flow directly in canine right heart bypass preparations.

Animals↗

Development of a clinical instrument to measure heel pad indentation.

OBJECTIVE: To provide an accurate, reliable, non-invasive, portable instrument to measure heel pad indentation in a clinical setting. DESIGN: A novel instrument was applied to assess heel pad indentation. BACKGROUND: For the lack of quantitative biomechanical tools for in vivo assessment, palpation is used to evaluate heel pad stiffness subjectively in everyday clinical practice. Furthermore, previous studies have evaluated heel pad stiffness using non-portable instrumentation. METHODS: Cylindrical probe was attached to an electronic force gauge unit that passed through a Perspex plate for placement on heel pad. Displacement of the plate was connected to a linear variable differential transformer. A laptop PC allowed for portability and storage of data. An exponential curve described the force-displacement data. Ten healthy subjects (mean 21. 7; SD, 1.7 years) were assessed on ten separate occasions. The procedure was standardised for subject position and placement. RESULTS: Accuracy and reliability of each device component was established. An intraclass correlation (2,1) of 0.90 and 0.88 demonstrated curve coefficients b1 and b0 respectively. A paired t-test demonstrated no significant difference between the left and right foot coefficients. CONCLUSION: The results demonstrated that each system component could be measured accurately and reliable. Reproducible results were obtained over separate occasions. The study has described a method to analyse the force-displacement curve. RelevanceThe development of a hand-held device may help the clinician to assess heel pad stiffness in the clinical setting. Heel pad stiffness may be associated in the development of plantar heel pain in athletes.

Adolescent↗

Thoracoscopic epicardial radiofrequency ablation for vagal atrial fibrillation in dogs.

Epicardial radiofrequency catheter ablation of the atria in the open-chest dog has been shown to reduce inducibility of atrial fibrillation. Video-assisted endoscopic techniques decrease the operative trauma in adult thoracic surgery. We report our results of video-assisted thoracoscopic radiofrequency catheter ablation of the atria for the prevention of atrial fibrillation induction in canines. In 12 consecutive anesthetized dogs, induction of sustained atrial fibrillation was reproducibly obtained by burst pacing and cervical vagal stimulation. In six dogs, biatrial ablation was performed through right and left minithoracotomies and guided by video-assisted endoscopic techniques. The remaining six dogs underwent a video-guided left atrial procedure. Long continuous and transmural lesions were produced using epicardial temperature controlled radiofrequency energy delivery according to a simplified maze approach. Transmural lesions were demonstrated at the end of the study by examination of the heart. Sustained atrial fibrillation was still inducible after the right atrial ablation but sustained atrial fibrillation could not be induced following left atrial ablation. In acute canine studies: (1) epicardial radiofrequency catheter ablation of the atria is feasible using video-assisted endoscopic techniques; (2) ablation extended or confined to the left atrium appears to be effective in preventing the inducibility of sustained vagal atrial fibrillation; and (3) ablation of the right atrium alone had no antiarrhythmic effect.

Animals↗

Morphological observations on the pathogenetic process of transposition of the great arteries induced by retinoic acid in mice.

BACKGROUND: The pathogenesis of complete transposition of the great arteries (TGA) is still controversial because useful animal models have not been established. We previously reported that all-trans retinoic acid induced complete TGA at a high proportion in mice. The aim of the present study was to clarify the morphogenesis of the cardiac outflow tract in the retinoic acid-treated embryos destined to develop TGA. METHODS AND RESULTS: We first examined the morphology of TGA in mouse fetuses treated with retinoic acid to establish an animal model of TGA (experiment 1) and then examined the retinoic acid-treated embryonic hearts by means of ink injection and histology (experiment 2). All mouse fetuses and embryos showed visceroatrial situs solitus and d-ventricular loop. In experiment 1, among 45 embryos treated with retinoic acid 70 mg/kg at day 8.5 of gestation, 35 (78%) had TGA and 3 (6.7%) had a double-outlet right ventricle with a subpulmonary ventricular septal defect. In experiment 2, all hearts already exhibited d-loop at gestation day 8.5. At gestation day 9.5, conus swellings, composed of acellular cardiac jelly, where hypoplastic, and the conotruncal cavity was nonspiral or tubular. At gestation day 11.0, aberrant conus swellings located anteroposteriorly to give a straight orientation to the conotruncal cavity. At gestation day 12.0, side-by-side great arteries were transposed in that the aorta arose from the right ventricle and the pulmonary artery arose above the interventricular foramen. CONCLUSIONS: These results suggest that a reproducible animal model of TGA can be produced in mice by treatment with retinoic acid; that there was no loop anomaly, such as an A-loop or L-loop, in our model; and that hypoplasia of the conus swellings appears to be the primary event leading to TGA.

Animals↗

Historic trials: Montreal Tramways v. Leveillé (1933) 4 DLR 338.

This trial concerned an injury in a newborn child which was allegedly caused by an accident involving the mother during her pregnancy. The trial is widely accepted as a turning-point in law related to fetal injury, conferring the right of a child to claim compensation at birth for injuries inflicted during pregnancy. This material is reproduced with the permission of the publisher, Canada Law Book Inc., 240 Edward Street, Aurora, Ontario L4G 3S9, Canada.

Accidents, Traffic↗

Evaluation and comparison of sources of variability in the measurement of corneal thickness with ultrasonic and optical pachymeters.

Two studies were carried out to determine and compare the effects of several sources of variation on the measurement of corneal thickness using the standard optical pachymeter and three ultrasonic pachymeters. Sources of variation included: intra- and inter-session variation, inter-observer variation, left/right eye variation, and variations due to alternate settings of ultrasonic sound frequencies. It was found that the optical pachymeter had a) two to three times as much intra-session variation as that of the ultrasound pachymeters, b) significant inter-observer variation (P = 0.015), and c) significant differences between left and right eye thickness determinations (P less than 0.005). On the other hand, ultrasonic pachymeters demonstrated a) high reproducibility, b) no inter-observer variation, and c) no left/right eye variation. These results have implications for the use of pachymetry in measuring corneal thickness for radial keratotomy and other refractive surgery.

Cornea↗

Intraoperative monitoring of the motor pathway using transtracheal stimulation of the cervical spine in dogs.

Although SEP monitoring of the spinal cord has been a well established method recently, not an ultimate, perfectly developed technique for monitoring of the motor system is known so far, particularly, because of the disturbing effect of narcotic drugs and relaxants on the motor evoked potentials. In this study the upper part of the spinal cord was stimulated in 14 anesthetized and relaxed dogs with a cathode attached to the intratracheal tube and an anode fixed to the cervical spinous processes. Single and serial stimuli were applied. Recordings were obtained from the exposed right femoral nerve and quadriceps muscle. Averaging was necessary when using serial stimulations. Responses were consequent and reproducible during regular anesthesia. The origin of the different responses in the spinal cord is discussed. The method seems to be appropriate for intraoperative monitoring of the thoracolumbar spine.

Anesthesia, General↗

Learning modifies subsequent induction of long-term potentiation-like and long-term depression-like plasticity in human motor cortex.

Learning may alter rapidly the output organization of adult motor cortex. It is a long-held hypothesis that modification of synaptic strength along cortical horizontal connections through long-term potentiation (LTP) and long-term depression (LTD) forms one important mechanism for learning-induced cortical plasticity. Strong evidence in favor of this hypothesis was provided for rat primary motor cortex (M1) by showing that motor learning reduced subsequent LTP but increased LTD. Whether a similar relationship exists in humans is unknown. Here, we induced LTP-like and LTD-like plasticity in the intact human M1 by an established paired associative stimulation (PAS) protocol. PAS consisted of 200 pairs of electrical stimulation of the right median nerve, followed by focal transcranial magnetic stimulation of the hand area of the left M1 at an interval equaling the individual N20 latency of the median nerve somatosensory-evoked cortical potential (PAS(N20)) or N20-5 msec (PAS(N20-5)). PAS(N20) induced reproducibly a LTP-like long-lasting (>30 min) increase in motor-evoked potentials from the left M1 to a thumb abductor muscle of the right hand, whereas PAS(N20-5) induced a LTD-like decrease. Repeated fastest possible thumb abduction movements resulted in learning, defined by an increase in maximum peak acceleration of the practiced movements, and prevented subsequent PAS(N20)-induced LTP-like plasticity but enhanced subsequent PAS(N20-5)-induced LTD-like plasticity. The same number of repeated slow thumb abduction movements did not result in learning and had no effects on PAS-induced plasticity. Findings support the view that learning in human M1 occurs through LTP-like mechanisms.

Adult↗

Isovolumetric relaxation time of the right ventricle assessed by tissue Doppler imaging.

OBJECTIVES: The isovolumetric relaxation time of the right ventricle (RV-IVRT) can be assessed using a method based on ECG and pulsed wave Doppler (PW). Recently pulsed wave Doppler tissue imaging (PW-DTI) has been introduced in the assessment. DESIGN: RV-IVRT obtained by the two methods was compared in 20 consecutive patients as was the time from the R wave on the ECG to the onset of tricuspid flow (R-T), to the closure of the pulmonic valve (R-P), to the onset of early diastolic motion of the tricuspid annulus tissue (R-E) and to the end of the systolic motion (R-S). RESULTS: RV-IVRT obtained by the PW method was significantly (p < 0.001) shorter than RV-IVRT obtained by PW-DTI. R-S had significantly (p < 0.001) shorter duration than R-P, while there was no significant difference between R-E and R-T. CONCLUSIONS: The methods are not measuring the same interval. Only the PW method measures RV-IVRT according to the usual definition. Different reference values have to be used if the methods are used in the assessment of RV diastolic function.

Echocardiography, Doppler, Pulsed↗

Sequence of echocardiographic changes during development of right ventricular failure in rat.

BACKGROUND: The temporal relations between the onset of echocardiographic changes and clinical diagnosis of right ventricular (RV) failure are unresolved. We have characterized such relations in a rat monocrotaline (MCT) model of RV failure. METHODS: Eight-week-old male Wistar rats were injected with MCT (60 mg/kg) or vehicle and underwent serial echocardiography. RV free-wall thickness (RVWT), pulmonary artery acceleration time normalized to cycle length (PAAT/CL), RV end-diastolic diameter (RVEDD), and tricuspid annular plane systolic excursion (TAPSE) were measured. RESULTS: Significant differences in echocardiographic parameters between MCT-treated and control rats were found as early as 14 days before RV failure for RVWT, 10 days for PAAT/CL, and 7 days for RVEDD and TAPSE. The time intervals between the onset of changes in RVWT, PAAT/CL, RVEDD, and TAPSE and diagnosis of RV failure were 11.3 +/- 0.8, 10.9 +/- 0.7, 6.5 +/- 0.5, and 5.4 +/- 0.7 days, respectively. The sequence of echocardiographic changes was consistent in all animals during development of RV failure. CONCLUSIONS: Pulmonary hypertension (assessed by PAAT/CL) and RV free-wall thickening (characterized by RVWT) precede RV dilation and RV systolic dysfunction (measured by RVEDD and TAPSE, respectively). Echocardiographic analysis permits accurate determination of the stage of disease development in MCT-induced RV failure.

Animals↗

An abnormal right ventricular apical angle is indicative of global right ventricular impairment.

The presence of right ventricular (RV) dysfunction is an adverse prognostic indicator but current echocardiographic methods have some limitations. RV apical angles in systole and diastole were correlated with known parameters of RV function in patients without pulmonary hypertension (Group 1) and in patients with pulmonary hypertension (Group 2). RV apical angles were significantly smaller in both systole (22 +/- 7 degrees) and diastole (33 +/- 6 degrees) in Group 1 patients when compared to Group 2 (54 +/- 18 degrees, p < 0.0001 and 59 +/- 17 degrees, p < 0.0001, respectively). RV apical angles, both in systole and diastole, were strongly correlated with RV end-systolic area (R = 0.89, p < 0.0001) and end-diastolic area (R = 0.81, p < 0.0001), respectively. Similarly, the apical systolic and diastolic angle correlated well with decreased tricuspid annular plane systolic excursion (TAPSE, R = -0.76 and R = -0.73, p < 0.001) as well as with decreased RV fractional area change (R = -0.81 and R = -0.77, p < 0.001). Therefore, we conclude that this new measurement of RV apical angle is simple and useful to quantify RV apical structural and functional abnormalities that are well correlated with global RV impairment in patients with chronic pulmonary hypertension.

Adult↗

Oral-facial-digital type I protein is required for primary cilia formation and left-right axis specification.

The oral-facial-digital type I (OFD1) syndrome (OMIM 311200) is a human developmental disorder; affected individuals have craniofacial and digital abnormalities and, in 15% of cases, polycystic kidney. The disease is inherited as an X-linked dominant male-lethal trait. Using a Cre-loxP system, we generated knockout animals lacking Ofd1 and reproduced the main features of the disease, albeit with increased severity, possibly owing to differences of X inactivation patterns between human and mouse. We found failure of left-right axis specification in mutant male embryos, and ultrastructural analysis showed a lack of cilia in the embryonic node. Formation of cilia was defective in cystic kidneys from heterozygous females, implicating ciliogenesis as a mechanism underlying cyst development. In addition, we found impaired patterning of the neural tube and altered expression of the 5' Hoxa and Hoxd genes in the limb buds of mice lacking Ofd1, suggesting that Ofd1 could have a role beyond primary cilium organization and assembly.

Animals↗

Far-field potentials as a method of monitoring acute and chronic spinal cord injury.

Far-field potentials (FFPs) were studied in monkeys to determine the utility of such responses in evaluating acute and chronic spinal cord injury. Monkeys (Macaca fascicularis) were anesthetized with 70% N2O 30% O2, immobilized with pancuronium bromide, and maintained on a respirator. Spinal cord transections were made at level T3-T4 and included bilateral dorsal columns or anterolateral columns, right or left hemisection, or central cord lesions. Percutaneous stimulation of both posterior tibial nerves was performed at a frequency of 3 Hz using 3-4 mA for 0.3 msec duration. Potentials were recorded from chronically implanted epidural electrodes (right ear reference) through a 300-3,000 Hz band pass filter. Each far-field potential represents the average of 256 individual responses recorded for a duration of 25 msec before and after cord lesion for up to 8 weeks. Seven reproducible components in the far-field potential could be identified. Following dorsal column transection all components were reduced in amplitude. After anterolateral column transection only latencies were altered. Right or left hemisections caused both attenuation of component amplitudes and latency alteration. Central cord lesions resulted in no detectable amplitude or latency disturbances. Control records likewise showed no changes. No major alterations, following day 1 posttransection, were observed, attesting to the relative stability of far-field potentials over long periods of time. Far-field potentials therefore may be useful in monitoring spinal cord injury.

Animals↗

[Quantification of right ventricular function in congenital heart disease: correlation of 3D echocardiography and MRI as complementary methods].

PURPOSE: In congenital heart disease, the exact determination of the right ventricular function is of high importance for therapeutic and especially surgical planning. The aim of this study was to correlate the parameters of the right ventricular function in MRI and 3D echocardiography to determine the agreement of both modalities. MATERIALS AND METHODS: In 18 patients suffering from congenital heart disease, 3D echocardiography was performed using a Philips Sonos 7500 system. In MRI short axis slices with a 4-mm distance were acquired using an SSFP sequence on a Siemens Sonata or Symphony System. Volumetry for both modalities was performed on an external workstation (Tomtec) using the EchoView software. RESULTS: Enddiastolic and endsystolic volumes showed a highly significant correlation with coefficients of 0.996 and 0.990, respectively. In echocardiography there was a systematic slight underestimation of enddiastolic volumes and overestimation of endsystolic volumes. The Wilcoxon test did not show significant differences between the volumes and ejection fractions assessed by both modalities. CONCLUSION: There is an excellent correlation in the quantification of right ventricular volumes in MRI and 3D echocardiography, which allows a comparison of acquired volumes in clinical follow-up.

Adolescent↗

Right ventricular injury in young swine: effects of catecholamines on right ventricular function and pulmonary vascular mechanics.

Acute right ventricular (RV) injury is commonly encountered in infants and children after cardiac surgery. Empiric medical therapy for these patients results from a paucity of data on which to base medical management and the absence of animal models that allow rigorous laboratory testing. Specifically, exogenous catecholamines have unclear effects on the injured right ventricle and pulmonary vasculature in the young. Ten anesthetized piglets (9-12 kg) were instrumented with epicardial transducers, micromanometers, and a pulmonary artery flow probe. RV injury was induced with a cryoablation probe. Dopamine at 10 microg/kg/min, dobutamine at 10 microg/kg/min, and epinephrine (EP) at 0.1 microg/kg/min were infused in a random order. RV contractility was evaluated using preload recruitable stroke work. Diastolic function was described by the end-diastolic pressure-volume relation, peak negative derivative of the pressure waveform, and peak filling rate. In addition to routine hemodynamic measurements, Fourier transformation of the pressure and flow waveforms allowed calculation of input resistance, characteristic impedance, RV total hydraulic power, and transpulmonary vascular efficiency. Cryoablation led to a stable reproducible injury, decreased preload recruitable stroke work, and impaired diastolic function as measured by all three indices. Infusion of each catecholamine improved preload recruitable stroke work and peak negative derivative of the pressure waveform. Dobutamine and EP both decreased indices of pulmonary vascular impedance, whereas EP was the only inotrope that significantly improved transpulmonary vascular efficiency. Although all three inotropes improved systolic and diastolic RV function, only EP decreased input resistance, decreased pulmonary vascular resistance, and increased transpulmonary vascular efficiency.

Animals↗

Anaglyphic three-dimensional stereoscopic printing: revival of an old method for anatomical and surgical teaching and reporting.

The authors describe how to use the three-dimensional (3D) anaglyphic method to produce stereoscopic prints for anatomical and surgical teaching and reports preparation by using currently available nonprofessional photographic and computer methods. As with any other method of producing stereoscopic images, the anaglyphic procedure is based on the superimposition of two slightly different images of the object to be reproduced, one seen more from a left-sided point of view and the other seen more from a right-sided point of view. The pictures are obtained using a single camera, which following the first shot can be slid along a special bar for the second shot, or by using two cameras affixed to a surgical microscope. After the images have been distinguished from each other by applying different complementary color dyes, the images are scanned and superimposed on each other with the aid of nonprofessional imaging-manipulation software used on a standard personal computer (PC), and are printed using a standard printer. To be seen stereoscopically, glasses with colored lenses, normally one red and one blue, have to be used. Stereoscopic 3D anaglyphic prints can be produced using standard photographic and PC equipment; after some training, the prints can be easily reproduced without significant cost and are particularly helpful to disclose the 3D character of anatomical structures.

Anatomy↗

Management of a patient with calcium pyrophosphate deposition disease and meniscal tear of the knee: a case report.

OBJECTIVE: To describe the chiropractic management of a patient suffering from a right lateral meniscus tear concurrent with calcium pyrophosphate dihydrate (CPPD) deposition disease. CLINICAL FEATURES: A 51-yr-old bus driver suffered from right knee pain (7 on a 1-10 pain scale). The onset of the pain was gradual and increased during braking and accelerating. Palpatory tenderness was noted at the right lateral knee joint line and the inferior lateral margin of the patella. Active resistive range of motion (ROM) in the knee during extension was painful throughout the full ROM, whereas passive ROM was restricted in flexion at 110 degrees. A positive McMurray's test reproduced pain at the knee. Radiographic analysis revealed CPPD deposition disease, and magnetic resonance imaging revealed a probable "parrot's beak" tear in the posterior horn of the right lateral meniscus. INTERVENTION AND OUTCOME: The patient was treated conservatively. He was instructed not to put weight on the knee and not to return to work for 5 days. Initial treatments involved the use of ice and interferential electrical stimulation along with glucosamine sulfate supplements. Bicycling, weight lifting for general fitness and general knee strengthening exercises were prescribed. Approximately 5 months after initial treatment, the patient was lost to follow-up; 12 months later, he returned for treatment because of a recurrence. Physical examination at that time revealed knee pain rated at 3/10 but there was no pain upon palpation, McMurray's test was negative and right knee ROM was full without pain. CONCLUSION: A patient suffering from CPPD can be managed by conservative means. The pathophysiology, clinical features and management considerations in the treatment of the patient's condition(s) are also discussed.

Chiropractic↗