VP Group Research Articles

Biomechanical Comparison of Fixed-Angle Volar Plate Versus Fixed-Angle Volar Plate Plus Fragment-Specific Fixation in a Cadaveric Distal Radius Fracture Model

To test the hypothesis that combining orthogonal fragment-specific fixation with volar fixed-angle fixation provides markedly higher interfragment stability and construct strength compared with volar fixed-angle fixation alone. Eight matched pairs of fresh cadaveric hand and forearm specimens were potted upright in cement. Flexor and extensor tendons were isolated at insertion sites and sutured into a looped bundle for loading in flexion and extension, respectively (up to 61 N). Osteotomies to simulate an AO type C2, 3-part fracture pattern were created with a saw. One randomized specimen from each pair received a locking volar plate and a radial pin plate (VP+PP), and the other received a locking volar plate only (VP). The relative angular displacements between the radial, ulnar, and proximal fragments were obtained with a motion analysis system. After stability tests, specimens were compressed to failure in a wrist-extended position on a material testing machine. Paired t tests were used to compare the interfragment displacement, construct stiffness, and strength between the 2 groups. Comparing fragment displacement in the VP+PP and VP groups showed that with flexion-extension and radial-ulnar deviation, distal fragment displacement was reduced to a statistically significant degree. The VP+PP group also showed higher failure strength and construct rigidity than the VP group. In a simulated cadaveric model of the distal radius intra-articular fracture, the combined technique of fragment-specific plating with volar fixed-angle fixation alone provides superior biomechanical strength and stability over the volar fixed-angle fixation alone.

Comparative hemodynamic effects of vasopressin and norepinephrine after milrinone-induced hypotension in off-pump coronary artery bypass surgical patients

Phosphodiesterase inhibitor is essential to the pharmacologic management of decompensated heart failure because it increases contractility and decreases afterload of right ventricle. It also improves hemodynamics and increases blood flow of the grafted internal mammary arteries and middle cerebral arteries during coronary artery bypass surgery. However, it induces vasodilation and necessitates the use of vasoconstrictors, such as norepinephrine. We hypothesized that vasopressin could recover hypotension induced by milrinone with less effect on pulmonary vascular resistance (PVR) compared to norepinephrine. Fifty patients, undergoing coronary artery bypass graft (CABG) surgery, were assigned randomly in a double-blind manner to receive either vasopressin or norepinephrine. After baseline hemodynamic measurements, a loading dose of milrinone 50 microg/kg was infused slowly for 20 min followed by continuous infusion of 0.5 microg/(kg min). Immediately after the loading dose of milrinone, hemodynamic variables were measured, and vasopressin (VP group) or norepinephrine (NE groups) was infused. After being titrated until the mean arterial pressure was increased by 20%, hemodynamic variables were measured again. Milrinone infusion reduced both systemic vascular resistance (SVR, 1218+/-299 dynes/cm5 vs 838+/-209 dynes/cm5, 1345+/-299 dynes/cm5 vs 1011+/-195 dynes/cm5) and PVR (95+/-34 dynes/cm5 vs 72+/-30 dynes/cm5, 119+/-85 dynes/cm5 vs 87+/-33 dynes/cm5) in the VP and NE groups, respectively. Vasopressin and norepinephrine infusion increased both SVR (838+/-209 dynes/cm5 vs 1100+/-244 dynes/cm5, 1011+/-195 dynes/cm5 vs 1446+/-681 dynes/cm5, respectively) and PVR (72+/-30 dynes/cm5 vs 84+/-18 dynes/cm5, 87+/-33 dynes/cm5 vs 139+/-97 dynes/cm5, respectively). The PRV/SVR ratio was decreased after vasopressin infusion (0.10+/-0.03 vs 0.08+/-0.03), while no changes were found after norepinephrine infusion (0.09+/-0.02 vs 0.09+/-0.02). In the patients undergoing CABG surgery, both norepinephrine and low dose vasopressin were effective in restoring milrinone-induced decrease of SVR. However, only low-dose vasopressin decreased the PVR/SVR ratio that was increased by milrinone. Considering the importance of maintaining systemic perfusion pressure as well as reducing right heart afterload, milrinone-vasopressin may provide better hemodynamics than milrinone-norephinephrine during the management of right heart failure.

Classification of ultrasonographic images of small hepatocellular carcinoma using galactose-based contrast agent: relation between image patterns and histologic features.

The aim of this study was to establish the relation between observed ultrasonographic (US) images produced with a galactose-based contrast agent and histologic characteristics of small hepatocellular carcinomas (HCCs). A total of 64 nodules in 64 patients, 22 well differentiated and 42 moderately differentiated with a histologically proven HCC, smaller than 3.0 cm in diameter and who had undergone hepatectomy were consecutively examined by contrast-enhanced US using a galactose-based contrast agent. Perfusion images were acquired by intermittent high-intensity, harmonic power Doppler sonography using a high pulse-repetition frequency and high-pass filter setting. Perfusion images of the arterial and late phases were classified into several patterns and compared with the histologic findings obtained from resected specimens. Most of the well- and moderately differentiated resected HCCs showed hyperechoic change during the arterial phase. However, 13 (59%) of the well-differentiated HCCs showed isoechoic change and 27 (64%) of the moderately differentiated HCCs showed hypoechoic change during the late phase. The difference is statistically significant (P < 0.0001). In a comparison of microscopic portal invasion (vp) of HCCs using enhanced US patterns, both vp(-) and vp(+) groups showed a high incidence of the hypervascular pattern during the arterial phase; in contrast, during the late phase 11 (73%) of 15 vp(+) nodules showed hypoechoic change with spotty signals. This difference is statistically significant (P < 0.0001) when compared with a high incidence (52%) of signal defect in the vp(-) group. The existence of well-differentiated components associated with the periphery of moderately differentiated HCCs also correlated closely with patterns during the late phase (P < 0.01). Late-phase contrast-enhanced US images of small HCCs with a galactose-based contrast agent are useful for predicting specific histologic characteristics.

The anatomy of a management buy-out

The business known today as the Virtalis Group of companies was originally set up in the late 1980s as the UK&apos;s National Advanced Robotics Research Centre in Salford, supported by the University, the DTI and a range of industrial shareholders. After a successful period of developing both hardware and software products, including the world&apos;s first tactile feedback glove systems for VR and telepresence applications, the Robotics Centre became commercial, launching VR Solutions Limited. In 1997, VR Solutions merged with Virtual Presence Limited (&apos;VP&apos;), a London-based hardware supplier, a significant move as it combined the technical excellence of the software development and consultancy teams with the necessary hardware to deliver complete solutions. Seen as one of the foremost interactive visualisation organisations in the world, the Group was purchased by the Nasdaq quoted Muse Inc. in order that further growth could be adequately funded. All went well initially, but US cash-flow difficulties led to a continual drain on the resources in the UK. Chapter 11 administration for the VP Group led to insolvency following almost inevitably. Recognising the value inherent within the people and the products and services, and noting the market&apos;s poor appetite for investment, particularly in the IT and technology sector, the only way forward was to carry out the buy-out, protecting people&apos;s jobs and keeping all the intellectual property together. This paper describes the buy-out process and the challenges involved.

Change of barometric pressure influences low back pain in patients with vacuum phenomenon within lumbar intervertebral disc.

The present study investigates whether changes in barometric pressure influence low back pain in patients with vacuum phenomenon within lumbar intervertebral discs. Twenty-four patients with low back pain were examined: 12 with vacuum phenomenon within the intervertebral discs (VP [+] group) and 12 without the vacuum phenomenon (VP [-] group). All patients consented to an evaluation of low back pain in a hyperbaric oxygen chamber. In the VP (+) group, low back pain became more severe in one patient when atmospheric pressure was elevated, and in eight patients when atmospheric pressure was decreased. In the VP (-) group, two patients experienced more severe low back pain when atmospheric pressure was decreased. Our study demonstrated that low back pain might be aggravated by atmosphere depression in patients with lumbar disease associated with the vacuum phenomenon.

A controlled study of vigabatrin and visual abnormalities

AIMSTo assess the visual function in epileptic patients who have received vigabatrin; to compare this with the visual function in similar epileptic patients who have never received vigabatrin; to investigate...

Training for Attentional Control in Novice Car Drivers: A Simulator Study

Novice drivers aged 18 to 25 are overrepresented in road accidents. This is partly due to an underdeveloped ability to control their attention. A driving simulator was used to enhance the attentional control skill of novice drivers, using Gopher's “variable priority” (VP) training technique. Three groups of novice drivers with varying on-road experience participated. Half the subjects in each group received VP training; the other half served as controls. All performed two tasks concurrently in the simulator, over 20 training trials. The VP group was instructed over trials to systematically vary the relative amount of attention given to each task. Control subjects were instructed to simply perform the two tasks as well as possible. After training, VP subjects performed significantly better than controls in a transfer of training drive in the simulator involving three sub-tasks, and this was particularly the case for those with greater driving experience. A follow-up experiment replicated and extended these findings.

VALIDITY OF TWO FIELD TESTS AS PREDICTORS OF AEROBIC CAPACITY IN COMPETITIVE ATHLETES.

1367 The purpose of this study was to compare the efficiency of Yo-Yo Endurance Test (YY) and 12-minute run (Cooper test) (CT) to determine the maximal oxygen uptake (VO2 max.) in elite athletes. We tested 31 competitive sport participants (CSP): 11 male (MH) and 12 female (FH) elite grass hockey players, and 8 male (VP) volley players of International level from the Argentine National Team. It included anthropometric measurements (somatotype), Anaerobic Threshold (Conconi Test)(A.T.), and YY and CT as predictors of aerobic capacity. All this athletes were developing regular training three times a week for the last eight months. Data showed the following results: TableTableStatistical analysis (t-test) showed: no significant difference in VO2 max. determinded with CT and YY in VP group (p=0.473); FH group(p=0.079) and low significant in MH group (p=0.048) (95% confidence interval). We conclude that YO-YO Endurance test not only give an accurately prediction of VO2 max., in competitive sport participants, but also is very useful because it lets determine the different speeds of each stage, specially A.T. level, and is an effective method for regulating exercise intensity for training sessions.

Venous dysfunction and the change of blood viscosity during head-up tilt.

The precise stimulus that induces vasovagal syncope is still unclear. We have previously demonstrated that the peripheral distribution of blood volume (venous pooling) is a strong predictor of tilt induced vasovagal reaction. We hypothesized that an increase in venous pooling during tilt accentuates the measured increase in blood viscosity. This hypothesis is based on the previously demonstrated increase in venous pressure and subsequent increase in transcapillary fluid transudation during tilt. The increased blood viscosity, in turn, increases vascular shear rate, which may alter the vasoconstrictive and other cardiovascular responses to decreased preload. We measured blood viscosity (supine and tilt) in 56 patients with a history of orthostatic intolerance (37 with venous pooling [VP] and 19 without venous pooling [non-VP]). VP and non-VP were separated into subgroups based on blood pressure and heart rate response to tilt. There was a positive correlation between blood viscosity and plasma aldosterone in the supine. In the group as a whole, neither supine blood viscosity nor its increase during tilt differed between VP and non-VP. However, the tilt induced increase of blood viscosity was significant only in patients with tilt provoked tachycardia plus normal blood pressure response in VP group. We suggest that the increase of blood viscosity in this group led to the normal blood pressure response. The positive correlation between supine blood viscosity and supine plasma aldosterone indicates that the normal blood pressure response in this group possibly was via stimulation of the renin-angiotensin-aldosterone system.

Signs and symptoms of temporomandibular disorders in adolescent violin players.

Signs and symptoms of temporomandibular disorders (TMDs) and the frequency of radiologically observed abnormalities in the condyles of temporomandibular joints (TMJs) of adolescent violin players (VP group) were investigated in a group of 31 music students and in their age- and sex-matched controls (C group). All subjects underwent a routine clinical stomatognathic examination, a standardized interview, and radiography of the condyles. The VP group reported a higher frequency of the subjective symptoms: pain in the TMJ when chewing, a feeling of stiffness in the TMJ, and clenching of the teeth. Clinically, the VP group showed a greater range of maximal protrusion and of maximal laterotrusion to the right, and a greater frequency of deviation to the right on opening. They also showed more palpatory tenderness in the masticatory muscles and pain in the TMJ on maximal opening. The number of playing years and the number of weekly playing hours correlated with several signs and symptoms of TMDs. In terms of radiologic findings in the condyles of the TMJs there was no difference between the groups. It is concluded that intense violin playing may have a predisposing role in the etiology of TMDs in adolescence.

Signs and symptoms of temporomandibular disorders and radiologically observed abnormalities in the condyles of the temporomandibular joints of professional violin and viola players.

The frequency of temporomandibular disorders (TMDs) and radiologically observed abnormalities in the condyles of the temporomandibular joints (TMJs) of professional violin and viola players was investigated in 26 orchestra violinists/violists (VP group) and in their sex-, age-, and dentition-matched controls (C group). A routine clinical stomatognathic examination, a standardized interview, and radiography of the condyles were carried out for all subjects. The VP group showed a higher frequency of subjective symptoms and clinical signs of TMD, such as palpatory tenderness of masticatory muscles, TMJ clicking, painful mandibular movements, and deviation on opening or closing. There was no difference between the groups in terms of radiologic findings in the condyles. Weekly playing hours correlated positively with some signs of TMD. It is concluded that professional violin or viola playing might be a predisposing factor for TMD.

Hyperdipsia produced by severing ventral septal fiber systems

The septum of male hooded rats (N = 59) was completely isolated from the rest of the brain (ISS) or was partially isolated by severing dorsal (DP), ventral (VP), anterior (AP), or posterior (PP) fiber tracts using a knife-cut technique. Daily water intakes and intakes following hypertonic NaCl and polyethylene glycol (PG) injections were measured. The septum totally degenerated for the ISS group and these rats had normal or hypodipsic daily intakes, likewise for intakes following NaCl and PG. Rats of the VP group sustained little septal damage, yet these cuts yielded the highest percentage (55 percent) of hyperdipsic daily drinkers of any group. The daily hyperdipsic rats drank normally in response to NaCl and PG, demonstrating a dissociation between daily drinking and drinking in response to specific thirst stimuli. The results indicate the importance of ventral fiber systems in the production of Septal Hyperdipsia, and support the notion that the septum has multiple effects upon water regulation.