Doppler ultrasonographic indices in diagnosing nutcracker syndrome in children

To elucidate the Doppler ultrasonographic cut-off value of nutcracker syndrome causing hematuria in children, we analyzed Doppler spectral findings between 15 children with nutcracker syndrome and 15 age- and sex-matched normal control subjects. A follow-up Doppler ultrasound (US) was also performed in children with nutcracker syndrome when hematuria subsided completely after a median period of 1.7 years (range: 1.0–3.5 years) (relieved nutcracker syndrome). The peak velocity (PV) ratios of the left renal vein (LRV) were significantly higher in children with nutcracker syndrome than in those with relieved nutcracker syndrome (P < 0.0001) and normal children (P < 0.0001). The PV ratios of the LRV at the follow-up US were significantly higher than those in the control subjects (P = 0.019). None of the 15 normal children showed PV ratios of the LRV > 3.7, but five of the 15 children with relieved nutcracker syndrome without hematuria had PV ratios of 3.91–5.02. When we set the cut-off values for nutcracker syndrome at the mean ± 2 SD (mean: 2.95 ± 0.92, range: 1.60–5.02) of 30 controls (normal children and relieved nutcracker without hematuria), the calculated cut-off value was 4.8, and the sensitivity and specificity were 100% and 93%, respectively. Given its high sensitivity, renal Doppler US can be used as a useful initial non-invasive test in the diagnosis of nutcracker syndrome in children with hematuria.     

Transcranial Doppler for evaluation of idiopathic intracranial hypertension

OBJECTIVES: The value of transcranial Doppler (TCD) ultrasonography in assessing patients with Idiopathic Intracranial Hypertension (IIH) is uncertain. We sought to determine the contribution of TCD to their evaluation. MATERIALS AND METHODS: Twenty-three patients with suspected IIH underwent TCD. Mean blood flow (BFV), peak systolic (PSV) and end-diastolic (EDV) velocities, and pulsatility (PI) and resistance (RI) indexes were obtained in the middle cerebral (MCA) and vertebral (VA) arteries and compared (Student's t-test) between patients with confirmed IIH and controls. IIH patients and controls were comparable in terms of age, gender and weight. RESULTS: The mean +/- SD BFV(MCA), PSV(MCA), EDV(MCA) and PI(VA) in the 13 IIH patients were higher than in the ten controls (59 +/- 6.8, 94 +/- 28.5, 43 +/- 12.4, 0.86 +/- 0.16 and 50 +/- 8.6, 72 +/- 25.8, 32 +/- 11.5, 0.58 +/- 0.45 respectively, P < 0.05) but still within normal values. The mean +/- SD PI(MCA), RI(MCA) and RI(VA) values in the IIH patients and controls were similar. CONCLUSIONS: TCD parameters had no useful unique features for monitoring IIH patients.     

Morphometric analysis of the fiber populations of the rat sciatic nerve, its spinal roots, and its major branches

Correspondence between the nerve composition and the functional characteristics of its fiber populations is not always evident. To investigate such correspondence and to give a systematic picture of the morphology of the rat hind limb nerves, extensive morphometric study was performed on the sciatic nerve, its founding dorsal and ventral spinal roots, and its major branches. Nerve histology was examined in semithin sections via microscopic image analysis. Variation in the density of myelinated fibers, fiber interspace, and nerve cross-sectional area was studied in individual roots and nerves. In the dorsal roots, fiber numbers and cross-sectional areas were directly linearly proportional to the spinal root level number. Constituent fiber populations were identified using multicomponent lognormal models, and an optimal model for every nerve or root was selected by using an information theoretic approach. For the dorsal and ventral roots and the sciatic and peroneal nerves, optimal fiber population models consisted of three components, whereas, for the tibial and sural nerves, two components were optimal. Functional identities of the revealed fiber populations were established by using calculations of corresponding conduction velocities according to Arbuthnott et al. (J. Physiol. [1980] 308:125-157) and anatomical considerations. It is anticipated that morphological parameters established in this study would advance the development of neural prostheses in humans. The proximodistal correspondences among the fiber populations of different nerves were established by parametric statistical comparisons. The proposed approach provides a conceptual framework for understanding the comparative anatomy of the peripheral nerves and spinal roots and can be further applied in other species.     

A highly sensitive automated complex running wheel test to detect latent motor deficits in the mouse MPTP model of Parkinson's disease

The subchronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridin (MPTP) paradigm is one of the most widely used in vivo models of Parkinson's disease (PD). However, particularly in the mouse model it has remained difficult to reliably detect behavioural correlates for PD. In the present study we apply a novel murine motor test, the motor skill sequence (MOSS) based on computerized recording of voluntary running wheel activity, and found latent motor skill deficits in the subchronic MPTP mouse model. Mice are first subjected to a 2-week training phase. The animals then receive either MPTP injections according to the standard subchronic MPTP paradigm (30 mg/kg) or vehicle injections for 5 consecutive days. Running performance transiently fell during the injection phase but returned to baseline within few days. The animals were then exposed to complex wheels with irregularly spaced crossbars demanding high central motor coordination abilities. Though both groups showed clear improvement of running performance in the learning phase on the complex wheel, MPTP animals displayed clear central motor deficits on the complex wheels, as indicated by a reduced maximum speed and running distance, despite unchanged running motivation. Our results demonstrate latent motor deficits in MPTP-treated mice, which can be unmasked by MOSS. MOSS is thus capable of detecting and quantifying central motor deficits in this widely used model of PD with high sensitivity. The automated full time data collection of several different running parameters makes it also a suitable test for efficient in vivo screening of potential therapeutic compounds in this model for PD.     

New echocardiographic applications for assessing global left ventricular diastolic function

A number of promising and highly technological echocardiographic imaging tools have recently been introduced to assess left ventricular diastolic function (i.e., the capacity of the ventricle to relax and fill). They permit quantification of distinct features of intraventricular blood flow velocity and pressure fields and myocardial tissue velocities. However, accurate interpretation of the new images and clinical indices is still cumbersome, as basic knowledge about intraventricular hemodynamics and ventricular wall mechanics is often insufficient. This review article provides a comprehensive and original overview of the hemodynamical and mechanical events that occur during diastole and discusses how this new information can be used in the clinical and research setting to evaluate diastolic function in the healthy and the diseased heart. It furthermore aims to explain the underpinnings of the techniques in such a way that the underlying biomechanical concepts (fluid dynamics and wall mechanics) become less obscure to cardiologists and echocardiographers and such that the biomedical engineers are given some insights into the avalanche of diastolic performance indices that currently exist.     

Evaluation of lens hardness in cataract surgery using high-frequency ultrasonic parameters in vitro

Ultrasonic parameters of sound velocity and frequency-dependent attenuation ranging from 25 to 45 MHz were measured for the purpose of evaluating the hardness of lenses in cataract surgery (phacoemulsification). Measurements were performed with a 35-MHz ultrasonic transducer on porcine lenses in which artificially cataracts were induced. The hardness of the cataractous lens was also evaluated by mechanical measurement of its elastic properties. The results indicated that the ultrasonic attenuation coefficients in normal porcine lenses were approximately 4.49 +/- 0.05 (mean +/- SD) and 6.32 +/- 0.04 dB/mm at 30 and 40 MHz, respectively. The development progression of the cataracts resulted in the attenuation coefficient increasing linearly to 7.36 +/- 0.25 and 11.1 +/- 0.92 dB/mm, respectively, corresponding to an increase of Young's modulus from 2.6 to 101.2 kPa. The sound velocity concomitantly increased from 1639.8 +/- 4.2 to 1735.6 +/- 10.4 m/s. Evaluation of the relationship between the phacoemulsification energy level and ultrasonic parameters in vitro by surgeons revealed that both the attenuation coefficient and sound velocity were linearly correlated with the phacoemulsification energy (r = 0.941 and 0.915, respectively). These results showed that measuring high-frequency ultrasonic parameters provides surgeons with good capability and reproducibility for selecting the optimal energy level for phacoemulsification.     

Glucose, insulin, diabetes and mechanisms of arterial dysfunction

1. This commentary reviews and discusses the association between increased arterial stiffness and indices of glucose and insulin metabolism and diabetes mellitus (DM). 2. Diabetes mellitus is associated with increased cardiovascular events, is an established major independent risk factor for cardiovascular disease and is included in current risk assessment algorithms. Based on Framingham risk assessment, the incremental risk due to DM, at a given level of baseline risk in non-diabetics, is approximately equivalent to 10 years and, at any given level of other major risk factors, DM increases risk three- to fourfold. 3. Increased aortic stiffness has been shown to be an independent risk factor for both cardiovascular and overall mortality in high-risk groups and recently in the general population. Both DM1 and DM2 are associated with accelerated stiffening of the elastic arteries, over and above that associated with normal ageing, and DM can be considered as imparting added biological age and, thus, added cardiovascular risk. 4. Aortic stiffness provides a plausible mechanism relating diabetes to increase cardiovascular disease. 5. A proportion of the increased risk of cardiovascular events in DM is a sequel of stiff arteries. Direct measures of arterial stiffness, such as aortic pulse wave velocity, are likely to be better candidates than pulse wave analysis for refining interventions to improve outcomes in diabetes.     

Effects of a divided high loading dose of caffeine on circulatory variables in preterm infants

BACKGROUND: A single high loading dose of 25 mg/kg caffeine has been shown to be effective for the prevention of apnoea, but may result in considerable reductions in blood flow velocity (BFV) in cerebral and intestinal arteries. OBJECTIVE: To assess the effects of two loading doses of 12.5 mg/kg caffeine given four hours apart on BFV in cerebral and intestinal arteries, left ventricular output (LVO), and plasma caffeine concentrations in preterm infants. DESIGN: Sixteen preterm neonates of <34 weeks gestation were investigated one hour after the first oral dose and one, two, and 20 hours after the second dose by Doppler sonography. RESULTS: The mean (SD) plasma caffeine concentrations were 31 (7) and 29 (7) mg/l at two and 20 hours respectively after the second dose. One hour after the first dose, none of the circulatory variables had changed significantly. One hour after the second caffeine dose, mean BFV in the internal carotid artery and anterior cerebral artery showed significant reductions of 17% and 19% (p = 0.01 and p = 0.003 respectively). BFV in the coeliac artery and superior mesenteric artery, LVO, PCO2, and respiratory rate had not changed significantly. Total vascular resistance, calculated as the ratio of mean blood pressure to LVO, had increased significantly one and two hours after the second dose (p = 0.049 and p = 0.023 respectively). CONCLUSION: A divided high loading dose of 25 mg/kg caffeine given four hours apart had decreased BFV in cerebral arteries after the second dose, whereas BFV in intestinal arteries and LVO were not affected.     

Hemodynamic effects of subclavian steal phenomenon on contralateral vertebral artery

PURPOSE: Increased blood flow velocity in the contralateral vertebral artery (VA) is a common finding in subclavian steal syndrome, but its clinical relevance is not known. The aim of this study was to investigate whether the degree of velocity increase in the contralateral VA correlated with the severity of the steal. METHODS: In a retrospective study of 62 patients with subclavian steal phenomenon and 62 sex- and age-matched controls, we analyzed the peak systolic velocity (PSV), end diastolic velocity (EDV), mean velocity (MV), resistance index (RI), and pulsatility index (PI) of the Doppler spectrum of the VA contralateral to the subclavian steal phenomenon. Clinical information including sex, age, comorbidities and Doppler data were recorded from the sonography registration form. RESULTS: In patients with subclavian steal syndrome, Doppler spectral analysis showed a complete reversal of flow in the VA in 29 patients (group A) and an alternating flow in 33 patients (group B). The PSV, MV, RI, and PI of the contralateral VA of patients from both groups were higher than in controls (p < 0.01 for both comparisons). The PSV, EDV, and MV in the contralateral VA were higher in patients with reversed flow compared with those with alternating flow (p < 0.05). Comparisons of clinical symptoms and comorbidities between the two groups did not yield significant findings. CONCLUSIONS: The degree of flow velocity increase in the contralateral VA artery correlates well with the severity of subclavian steal phenomenon.     

Ultrasonometric evaluation of bone healing: Experimental study using a model of diaphyseal transverse osteotomy of sheep tibiae

Noninvasive ionizing-radiation-free methods of evaluation, such as ultrasonometry, are desirable in any medical situation. An in vitro ultrasonometric study was undertaken to evaluate the bone healing process of sheep tibiae submitted to a diaphyseal transverse osteotomy at different times after the procedure. Fifteen sheep weighing an average of 37 kg had surgery for a transverse mid-diaphyseal osteotomy of the right tibia; they were divided postoperatively into three groups of five for periods of observation at 30, 45 and 60 days. The intact left tibiae of the 15 animals were used for control. The healing process was monitored with conventional radiographs taken at two-week intervals, and the animals were killed at the end of the period of observation of each group. Both surgical and intact tibiae were removed, their diameters were measured and they were submitted to measurement of underwater ultrasound propagation velocities (USPV) at the osteotomy sites in both the sagittal and frontal planes. The diameters of the surgical tibiae decreased with time in both planes (from 26.9 mm to 22.0 mm and to 20.9 mm in the sagittal plane, and from 29.3 mm to 23.9 mm and to 23 mm in the frontal plane), with significant differences between the periods of observation (p < or = 0.018 and p < or = 0.003 between 30 and 45 days and 30 and 60 days, respectively, for the sagittal plane and p < or = 0.006 and p < or = 0.003 between 30 and 45 days and 30 and 60 days, respectively, for the frontal plane) and between surgical and intact tibiae at all time points (p < or = 0.0005 for each comparison). USPV increased with time from 2290 m/s to 2399 m/s and to 2382 m/s in the sagittal plane, and from 2376 m/s to 2472 m/s and to 2466 m/s in the frontal plane, accounting for an approximate 5% difference between 30 and 60 days Differences between the surgical and intact tibiae were significant at all time points (p < or = 0.0005 for both sagittal and frontal planes) but not between periods for either plane. There was a strong negative correlation between diameter and USPV (Pearson's correlation coefficient of -0.8998 for the sagittal plane and -0.9192 for the frontal plane). It was concluded that ultrasonometric evaluation of the bone healing process is feasible, yielding precise and reliable results, with a potential for clinical application.