Cast immobilization duration for distal radius fractures, a systematic review.

PURPOSE: The optimal duration of immobilization for the conservative treatment of non- or minimally displaced and displaced distal radius fractures remains under debate. This research aims to review studies of these treatments to add evidence regarding the optimal immobilization period. METHODS: A comprehensive database search was conducted. Studies investigating and comparing short (< 3 weeks) versus long (> 3 weeks) immobilizations for the conservative treatment of distal radius fractures were included. The studies were evaluated for radiological and functional outcomes, including pain, grip strength, and range of motion. Two reviewers independently reviewed all studies and performed the data extraction. RESULTS: The initial database search identified 11.981 studies, of which 16 (involving 1.118 patients) were ultimately included. Patient-reported outcome measurements, grip strength, range of motion, and radiological outcomes were often better after shorter immobilization treatments. Radiological outcomes were better with longer immobilization in two studies and shorter immobilization in one study. Fourteen studies concluded that early mobilization is preferred, while the remaining two studies observed better outcomes with longer immobilization. The data were unsuitable for meta-analysis due to their heterogeneous nature. CONCLUSION: Shorter immobilization for conservatively treated distal radius fractures often yield equal or better outcomes than longer immobilizations. The immobilization for non- or minimally displaced distal radius fractures could therefore be shortened to 3 weeks or less. Displaced and reduced distal radius fractures cannot be immobilized shorter than 4 weeks due to the risk of complications. Future research with homogeneous groups could elucidate the optimal duration of immobilization.

The past, present and future of the conservative treatment of distal radius fractures.

The distal radius fracture is a common fracture with a prevalence of 17% on the emergency departments. The conservative treatment of distal radius fractures usually consists of three to six weeks of plaster immobilization. Several studies show that one week of plaster immobilization is safe for non- or minimally displaced distal radius fractures that do not need reduction. A shorter period of immobilization may lead to a better functional outcome, faster reintegration and participation in daily activities. Due to upcoming innovations such as three-dimensional printed splints for distal radius fractures, a patient specific splint can be produced which may offer more comfort. Furthermore, these three-dimensional printed splints are expected to be more environmental friendly in comparison with traditional plaster casts.

Can CT-based gap and step-off displacement predict outcome after nonoperative treatment of acetabular fractures?

Aims: The aim of this study was to investigate the association between fracture displacement and survivorship of the native hip joint without conversion to a total hip arthroplasty (THA), and to determine predictors for conversion to THA in patients treated nonoperatively for acetabular fractures. Methods: A multicentre cross-sectional study was performed in 170 patients who were treated nonoperatively for an acetabular fracture in three level 1 trauma centres. Using the post-injury diagnostic CT scan, the maximum gap and step-off values in the weightbearing dome were digitally measured by two trauma surgeons. Native hip survival was reported using Kaplan-Meier curves. Predictors for conversion to THA were determined using Cox regression analysis. Results: Of 170 patients, 22 (13%) subsequently received a THA. Native hip survival in patients with a step-off ≤ 2 mm, > 2 to 4 mm, or > 4 mm differed at five-year follow-up (respectively: 94% vs 70% vs 74%). Native hip survival in patients with a gap ≤ 2 mm, > 2 to 4 mm, or > 4 mm differed at five-year follow-up (respectively: 100% vs 84% vs 78%). Step-off displacement > 2 mm (> 2 to 4 mm hazard ratio (HR) 4.9, > 4 mm HR 5.6) and age > 60 years (HR 2.9) were independent predictors for conversion to THA at follow-up. Conclusion: Patients with minimally displaced acetabular fractures who opt for nonoperative fracture treatment may be informed that fracture displacement (e.g. gap and step-off) up to 2 mm, as measured on CT images, results in limited risk on conversion to THA. Step-off ≥ 2 mm and age > 60 years are predictors for conversion to THA and can be helpful in the shared decision-making process.

Entry Point Variation in the Osseous Fixation Pathway of the Anterior Column of the Pelvis-A Three-Dimensional Analysis.

Fractures of the superior pubic ramus can be treated with screw insertion into the osseous fixation pathway (OFP) of the anterior column (AC). The entry point determines whether the screw exits the OFP prematurely. This can be harmful when it enters the hip joint or damages soft tissues inside the lesser pelvis. The exact entry point varies between patients and can be difficult to ascertain on fluoroscopy during surgery. The aim of this study was to determine variation in the location of the entry point. A retrospective single center study was performed at a level 1 trauma center in the Netherlands. Nineteen adult patients were included with an undisplaced fracture of the superior pubic ramus on computer tomography (CT)-scan. Virtual three-dimensional (3D) models of the pelvises were created. Multiple screws were placed per AC and the models were superimposed. A total of 157 screws were placed, of which 109 did not exit the OFP prematurely. A universally reproducible entry point could not be identified. A typical crescent shaped region of entry points did exist and was located more laterally in females when compared to males. Three-dimensional virtual surgery planning can be helpful to identify the ideal entry points in each case.

Accuracy of Patient-Specific Drilling Guides in Acetabular Fracture Surgery: A Human Cadaver Study.

Due to the complex anatomical shape of the pelvis, screw placement can be challenging in acetabular fracture surgery. This study aims to assess the accuracy of screw placement using patient-specific surgical drilling guides applied to pre-contoured conventional implants in acetabular fracture surgery. CT scans were made of four human cadavers to create 3D models of each (unfractured) pelvis. Implants were pre-contoured on 3D printed pelvic models and optically scanned. Following virtual preoperative planning, surgical drilling guides were designed to fit on top of the implant and were 3D printed. The differences between the pre-planned and actual screw directions (degrees) and screw entry points (mm) were assessed from the pre- and postoperative CT-scans. The median difference between the planned and actual screw direction was 5.9° (IQR: 4-8°) for the in-plate screws and 7.6° (IQR: 6-10°) for the infra-acetabular and column screws. The median entry point differences were 3.6 (IQR: 2-5) mm for the in-plate screws and 2.6 (IQR: 2-3) mm for the infra-acetabular and column screws. No screws penetrated into the hip joint or caused soft tissue injuries. Three-dimensional preoperative planning in combination with surgical guides that envelope pre-contoured conventional implants result in accurate screw placement during acetabular fracture surgery.

What Are the Interobserver and Intraobserver Variability of Gap and Stepoff Measurements in Acetabular Fractures?

BACKGROUND: Gap and stepoff values in the treatment of acetabular fractures are correlated with clinical outcomes. However, the interobserver and intraobserver variability of gap and stepoff measurements for all imaging modalities in the preoperative, intraoperative, and postoperative phase of treatment is unknown. Recently, a standardized CT-based measurement method was introduced, which provided the opportunity to assess the level of variability. QUESTIONS/PURPOSES: (1) In patients with acetabular fractures, what is the interobserver variability in the measurement of the fracture gaps and articular stepoffs determined by each observer to be the maximum one in the weightbearing dome, as measured on pre- and postoperative pelvic radiographs, intraoperative fluoroscopy, and pre- and postoperative CT scans? (2) What is the intraobserver variability in these measurements? METHODS: Sixty patients with a complete subset of pre-, intra- and postoperative high-quality images (CT slices of < 2 mm), representing a variety of fracture types with small and large gaps and/or stepoffs, were included. A total of 196 patients with nonoperative treatment (n = 117), inadequate available imaging (n = 60), skeletal immaturity (n = 16), bilateral fractures (n = 2) or a primary THA (n = 1) were excluded. The maximum gap and stepoff values in the weightbearing dome were digitally measured on pelvic radiographs and CT images by five independent observers. Observers were free to decide which gap and/or stepoff they considered the maximum and then measure these before and after surgery. The observers were two trauma surgeons with more than 5 years of experience in pelvic surgery, two trauma surgeons with less than 5 years of experience in pelvic surgery, and one surgical resident. Additionally, the final intraoperative fluoroscopy images were assessed for the presence of a gap or stepoff in the weightbearing dome. All observers used the same standardized measurement technique and each observer measured the first five patients together with the responsible researcher. For 10 randomly selected patients, all measurements were repeated by all observers, at least 2 weeks after the initial measurements. The intraclass correlation coefficient (ICC) for pelvic radiographs and CT images and the kappa value for intraoperative fluoroscopy measurements were calculated to determine the inter- and intraobserver variability. Interobserver variability was defined as the difference in the measurements between observers. Intraobserver variability was defined as the difference in repeated measurements by the same observer. RESULTS: Preoperatively, the interobserver ICC was 0.4 (gap and stepoff) on radiographs and 0.4 (gap) and 0.3 (stepoff) on CT images. The observers agreed on the indication for surgery in 40% (gap) and 30% (stepoff) on pelvic radiographs. For CT scans the observers agreed in 95% (gap) and 70% (stepoff) of images. Postoperatively, the interobserver ICC was 0.4 (gap) and 0.2 (stepoff) on radiographs. The observers agreed on whether the reduction was acceptable or not in 60% (gap) and 40% (stepoff). On CT images the ICC was 0.3 (gap) and 0.4 (stepoff). The observers agreed on whether the reduction was acceptable in 35% (gap) and 38% (stepoff). The preoperative intraobserver ICC was 0.6 (gap and stepoff) on pelvic radiographs and 0.4 (gap) and 0.6 (stepoff) for CT scans. Postoperatively, the intraobserver ICC was 0.7 (gap) and 0.1 (stepoff) on pelvic radiographs. On CT the intraobserver ICC was 0.5 (gap) and 0.3 (stepoff). There was no agreement between the observers on the presence of a gap or stepoff on intraoperative fluoroscopy images (kappa -0.1 to 0.2). CONCLUSIONS: We found an insufficient interobserver and intraobserver agreement on measuring gaps and stepoffs for supporting clinical decisions in acetabular fracture surgery. If observers cannot agree on the size of the gap and stepoff, it will be challenging to decide when to perform surgery and study the results of acetabular fracture surgery. LEVEL OF EVIDENCE: Level III, diagnostic study.

[Visual impairment following a suicide attempt with a crossbow]. / 'Ziende blind' na een suïcidepoging met kruisboog.

BACKGROUND: Bálint's syndrome is characterized by the triad of ocular apraxia, dorsal simultanagnosia and optic ataxia. It most commonly occurs following bilateral parieto-occipital brain injury, for which several aetiologies have been described. CASE DESCRIPTION: We present a case of a 39-year-old male with penetrating brain injury following a suicide attempt with a crossbow. A CT scan of the head revealed the intracranial position of the arrow, piercing the parietal and occipital cortex from the left-parietal direction with the tip on the right parietal bone. After surgical removal of the arrow, visuospatial symptoms persisted that were consistent with Bálint's syndrome. The characteristic symptoms, patho-anatomy and treatment of this syndrome are discussed in this article. CONCLUSION: The patient in this case had visual impairment following a suicide attempt with a crossbow. On the basis of neurological and neuropsychological assessments, the triad of ocular apraxia, dorsal simultanagnosia and optic ataxia was observed, characteristic of Bálint's syndrome.

Measuring the electrophysiological effects of direct electrical stimulation after awake brain surgery.

OBJECTIVE: Direct electrical stimulation (DES) at 60 Hz is used to perform real-time functional mapping of the brain, and guide tumour resection during awake neurosurgery. Nonetheless, the electrophysiological effects of DES remain largely unknown, both locally and remotely. APPROACH: In this study, we lowered the DES frequency to 1-10 Hz and we used a differential recording mode of electro-corticographic (ECoG) signals to improve the focality with a simple algorithm to remove the artefacts due to the response of the acquisition chain. MAIN RESULTS: Doing so, we were able to observe different components in the evoked potentials triggered by simulating the cortex or the subcortical white matter pathways near the recording electrodes and by stimulating the cortex remotely from the recording site. More particularly, P0 and N1 components were repeatedly observed on raw ECoG signals without the need to average the data. SIGNIFICANCE: This new methodology is important to probe the electrophysiological states and the connectivity of the brain in vivo and in real time, namely to perform electrophysiological brain mapping on human patients operated in the neurosurgical room and to better understand the electrophysiological spreading of DES.

Postoperative Pain After Laparoscopic Repair of Primary Umbilical Hernia: Titanium Tacks Versus Absorbable Tacks: A Prospective Comparative Cohort Analysis of 80 Patients With a Long-term Follow-up.

We investigated if a novel fixation device with absorbable tacks (Securestrap) causes less early and chronic postoperative pain after laparoscopic repair with a double-crown mesh fixation of ventral abdominal wall hernia when compared with the standard fixation device with nonabsorbable titanium tacks (Protack). The primary outcome measure was early postoperative pain at 2, 6, and 12 weeks postoperatively. The secondary outcome measure was chronic postoperative pain measured ≥18 months after surgery. Pain levels were assessed using a visual analog scale ranging from 0 (no pain) to 100 mm (excruciating pain). Early postoperative pain was significantly lower in group 2 (absorbable tacks) at 6 (2 vs. 5; P=0.008) and 12 weeks (1 vs. 2; P=0.008) but not at follow-up (6 vs. 11; P=0.21). Given the very low visual analog scale scores in both groups, the clinical significance of these finding remains open to discussion.

Intraperitoneal onlay mesh reinforcement of the abdominal wall: a new surgical option for treatment of anterior cutaneous nerve entrapment syndrome-a retrospective cohort analysis of 30 consecutive patients.

BACKGROUND: The aim of the study was to introduce a new surgical treatment for anterior cutaneous nerve entrapment syndrome, a frequently unrecognised disorder in the general population responsible for chronic abdominal wall pain with limited treatment options to date. We hypothesised that intraperitoneal onlay mesh reinforcement could dissipate excessive increases in intra-abdominal pressure and prevent entrapment of the neurovascular bundle. METHODS: Retrospective cohort analysis was performed between September 2002 and March 2014. All consecutive patients diagnosed with anterior cutaneous nerve entrapment syndrome refractory to conservative treatment (n = 30) underwent laparoscopic intraperitoneal onlay mesh reinforcement of the painful area in the abdominal wall. Planned follow-up took place at 2, 6 and 12 weeks after surgery and at time of analysis (March 2015). Primary outcome was patients' satisfaction after treatment at short and long term (last follow-up) using a verbal rating score as measurement (1 = I am very satisfied; I never experience pain, 2 = I am satisfied; I occasionally experience some pain, 3 = I have improved but experience pain on a regular basis, 4 = I have had no result on this treatment, 5 = my pain is worse after treatment). Scores 1 and 2 were classified as success, and scores 4 and 5 as failure of the treatment. RESULTS: Thirty patients underwent laparoscopic intraperitoneal onlay mesh reinforcement. None were lost to follow-up (mean 54 ± 44 months, range 12-122, median 38). Short- and long-term success rates were 90 and 71 %, respectfully. CONCLUSIONS: Intraperitoneal onlay mesh reinforcement of the abdominal wall seems to be a promising option for the treatment of intractable anterior cutaneous nerve entrapment syndrome.

[A woman with a seat belt sign after a car accident]. / Een vrouw met een gordelafdruk na een ongeval.

A 48-year-old woman presented with a cervicothoracic seat belt sign after a car accident as a front seat passenger. The CT scan showed right common carotid artery dissection with a pseudoaneurysm, a right clavicle fracture, sternal fracture, multiple rib fractures left and a laceration of the spleen. She did not develop any neurologic deficits.

Laparoscopic repair of primary and incisional ventral hernias: the differences must be acknowledged: a prospective cohort analysis of 1,088 consecutive patients.

BACKGROUND: Interpretation of the outcome after laparoscopic repair (LR) of ventral hernias presented in the literature often is based on pooled data of primary ventral hernias (PVH) and incisional ventral hernias (IVH). This prospective cohort study was performed to investigate whether this pooling of data is justified. METHODS: The data of 1,088 consecutive patients who underwent LR of PVH or IVH were prospectively collected and reviewed for baseline characteristics, operative findings, and postoperative complications classified as Clavien grade 3 or higher. RESULTS: The PVH group consisted of 662 patients, and the IVH group comprised 426 patients. The mean Association of American Anesthesiologists classification was higher in IVH group (1.92 vs 1.68; P ≤ 0.001), as was rate of conversion to open surgery (7 vs 0.5 %; P < 0.001). The IVH group required more adhesiolysis (76 vs 0.9 %; P < 0.001), a longer procedure (73 vs 42 min; P < 0.001), and a longer hospital stay (4.53 vs 2.43 days; P < 0.001). The recurrence rate was higher in the IVH group (5.81 vs 1.37 %; P < 0.001), as was total complication rate (18.69 vs 4.55 %; P < 0.001). CONCLUSIONS: This study showed significant differences in baseline characteristics and operative findings between patients undergoing PVH repair and those undergoing IVH repair. Continued pooling of data on LR of IVH and PVH combined, commonly found in the current literature, seems incorrect.

Inhibiting NOS blocks microvascular recruitment and blunts muscle glucose uptake in response to insulin.

We examined the effects of inhibiting nitric oxide synthase with Nomega-nitro-l-arginine-methyl ester (l-NAME) on total hindlimb blood flow, muscle microvascular recruitment, and hindlimb glucose uptake during euglycemic hyperinsulinemia in vivo in the rat. We used two independent methods to measure microvascular perfusion. In one group of animals, microvascular recruitment was measured using the metabolism of exogenously infused 1-methylxanthine (1-MX), and in a second group contrast-enhanced ultrasound (CEU) was used. Limb glucose uptake was measured by arterial-venous concentration differences after 2 h of insulin infusion. Saline alone did not alter femoral artery flow, glucose uptake, or 1-MX metabolism. Insulin (10 mU.min-1.kg-1) significantly increased hindlimb total blood flow (0.69 +/- 0.02 to 1.22 +/- 0.11 ml/min, P < 0.05), glucose uptake (0.27 +/- 0.05 to 0.95 +/- 0.08 micromol/min, P < 0.05), 1-MX uptake (5.0 +/- 0.5 to 8.5 +/- 1.0 nmol/min, P < 0.05), and skeletal muscle microvascular volume measured by CEU (10.0 +/- 1.6 to 15.0 +/- 1.2 video intensity units, P < 0.05). Addition of l-NAME to insulin completely blocked the effect of insulin on both total limb flow and microvascular recruitment (measured using either 1-MX or CEU) and blunted glucose uptake by 40% (P < 0.05). We conclude that insulin specifically recruits flow to the microvasculture in skeletal muscle via a nitric oxide-dependent pathway and that this may be important to insulin's overall action to regulate glucose disposal.

Skeletal muscle microvascular recruitment by physiological hyperinsulinemia precedes increases in total blood flow.

Supraphysiological doses of insulin enhance total limb blood flow and recruit capillaries in skeletal muscle. Whether these processes change in response to physiological hyperinsulinemia is uncertain. To examine this, we infused either saline (n = 6) or insulin (euglycemic clamp, 3.0 mU x min(-1) x kg(-1), n = 9) into anesthetized rats for 120 min. Femoral artery flow was monitored continuously using a Doppler flow probe, and muscle microvascular recruitment was assessed by metabolism of infused 1-methylxanthine (1-MX) and by contrast-enhanced ultrasound (CEU). Insulin infusion raised plasma insulin concentrations by approximately 10-fold. Compared with saline, physiological hyperinsulinemia increased femoral artery flow (1.02 +/- 0.10 vs. 0.68 +/- 0.09 ml/min; P < 0.05), microvascular recruitment (measured by 1-MX metabolism [6.6 +/- 0.5 vs. 4.5 +/- 0.48 nmol/min; P < 0.05] as well as by CEU [167.0 +/- 39.8 vs. 28.2 +/- 13.8%; P < 0.01]), and microvascular flow velocity (beta, 0.14 +/- 0.02 vs. 0.09 +/- 0.02 s(-1)). Subsequently, we studied the time dependency of insulin's vascular action in a second group (n = 5) of animals. Using CEU, microvascular volume was measured at 0, 30, and 90 min of insulin infusion. Insulin augmented microvascular perfusion within 30 min (52.8 +/- 14.8%), and this persisted at 90 min (64.6 +/- 9.9%). Microvascular recruitment occurred without changes to femoral artery flow or beta. We conclude that insulin increases tissue perfusion by recruiting microvascular beds, and at physiological concentrations this precedes increases in total muscle blood flow by 60-90 min.

Size-dependent effects of microspheres on vasoconstrictor-mediated change in oxygen uptake by perfused rat hindlimb.

There are two vascular flow routes in skeletal muscle that can be accessed by different vasoconstrictors acting at selective sites in the vascular tree. Thus, angiotensin II (AII) and serotonin (5-HT), which stimulate and inhibit metabolism, do so by directing flow to nutritive and nonnutritive routes, respectively. In the present study the association between vascular flow route recruitment and metabolism was assessed by embolism with microspheres of different sizes. Latex microspheres (MS) of four sizes, 5.4 (MS5), 11.8 (MS12), 23.4 (MS23), and 93.6 microm (MS94), were injected during AII- or 5-HT-mediated constriction or under basal conditions and the effects on hindlimb oxygen uptake (VO2), perfusion pressure, and venous flow rate were determined. MS5 or MS12 partially reversed 5-HT-mediated inhibition of VO2 by 39 and 55%, respectively (P < 0.05), fully reversed AII-mediated stimulation of VO2 (P < 0.05), stimulated basal VO2 (P < 0.05), and increased pressure while only marginally (<10%) decreasing venous flow. MS23 or MS94 dose-dependently increased pressure and inhibited VO2, during basal or 5HT- and AII-mediated constriction, while only marginally decreasing venous flow. In conclusion, microspheres of less than 12 microm when injected into the constant flow perfused rat hindlimb can alter metabolism by altering flow distribution between nutritive and nonnutritive routes. Larger MS (> or =24 microm) are nondiscriminating possibly because they exceed the size of vessels in which branch points to the two vascular routes are located. Overall the findings provide further evidence for two microvascular routes in muscle, one nutritive and the other nonnutritive.

Spatial distribution of nutritive and nonnutritive vascular routes in perfused rat hindlimb muscle using microspheres.

Skeletal muscle appears to have two vascular flow routes, nutritive and nonnutritive, where the balance of flow is controlled by vasoconstrictors. In the present study, spatial distributions of the two flow routes in muscles of the perfused rat hindlimb were attempted using fluorescent microspheres (15 microm in diameter). Microspheres were injected during steady-state perfusion with norepinephrine (proposed recruiter of nutritive flow), serotonin (proposed recruiter of nonnutritive flow), or vehicle. The three-dimensional location of individual microspheres in representative muscles was determined using a Fluorescent Imaging CryoMicrotome. Norepinephrine and serotonin each increased perfusion pressure (P < 0.05) but stimulated and inhibited oxygen consumption (P < 0.05), respectively. The distribution of microspheres lodged in muscle was independent of the agent used. Spatial perfusion indices for norepinephrine, serotonin, and vehicle did not differ from each other. Similarly, there was no difference in these indices for a theoretical distribution where microspheres were deliberately positioned in muscle bundle capillaries or interfibrillar connective tissue vessels. We conclude that the nutritive and nonnutritive flow routes are distributed throughout muscle sections consistent with their locations in muscle bundle capillaries and interfibrillar connective tissue, respectively.

Functional and desensitizing effects of the novel synthetic vanilloid-like agent 12-phenylacetate 13-acetate 20-homovanillate (PPAHV) in the perfused rat hindlimb.

1. In the present study, the effects of the novel vanilloid agonist, 12-phenylacetate 13-acetate 20-homovanillate (PPAHV), on oxygen consumption (VO(2)) and vascular resistance (perfusion pressure, PP) were investigated in the constant flow, perfused rat hindlimb. The acute desensitizing properties of this novel synthetic agent were also examined. 2. Maximum stimulation of VO(2) was produced by 0.2 microM PPAHV (delta VO(2), 0.83+/-0.06 micromol g(-1) h(-1)) and was accompanied by mild vasoconstriction (increase in PP; 8.0+/-1.1 mmHg). The highest concentration of PPAHV tested (2 microM) caused inhibition of VO(2) (delta VO(2), -2.73+/-0.51 micromol g(-1) h(-1)) and strong vasoconstriction (delta PP, 42.0+/-1.2 mmHg). 3. Capsazepine (10 microM) caused a parallel shift to the right of both VO(2) and PP concentration-response curves for PPAHV (pK(b)=5.00), indicative of competitive binding to vanilloid receptors. 4. The stimulation of VO(2) produced by 0.2 microM PPAHV decreased, but was not completely abolished, after repeated infusion of PPAHV (change in VO(2), first infusion, 0.66+/-0.18 micromol g(-1) h(-1); sixth infusion, 0.29+/-0. 08 micromol g(-1) h(-1), P<0.05), an acute tachyphylactic response not previously seen with the repeated infusion of other vanilloid analogues. Conversely, the PP response to repeated PPAHV infusion increased (delta PP, first infusion, 5.8+/-0.7 mmHg; sixth infusion, 9.0+/-0.6 mmHg, P<0.05). 5. In conclusion, PPAHV produces vasoconstriction and a biphasic effect on VO(2) in the perfused rat hindlimb very similar to that induced by naturally occurring vanilloids. Both effects are blocked by the competitive antagonist capsazepine. Since, the metabolic response to low concentrations of PPAHV (stimulation of VO(2)) undergoes tachyphylaxis, the present data suggest that PPAHV desensitizes putative vanilloid receptors in the hindlimb.

Nutritive and non-nutritive blood flow: rest and exercise.

There is growing evidence to support the notion of two vascular routes within, or closely associated with skeletal muscle. One route is in intimate contact with muscle cells (hence is known as 'nutritive') and the other functions as a vascular shunt (and has had the interesting misnomer of 'non-nutritive'). Recent findings suggest that the 'non-nutritive' route may, in part, be those vessels in closely associated (interlacing?) connective tissue that nourishes attached fat cells, and may form the basis of 'marbling' of muscle in obesity. In addition, embolism studies using various size microspheres indicate that the 'non-nutritive' vessels are likely to be capillaries fed by terminal arterioles that branch from the same transverse arterioles as those supplying terminal arterioles of the muscle capillaries (i.e. two vascular systems operating in parallel). The proportion of flow distributed between the two routes is tightly regulated and controls muscle metabolism and contraction by regulating hormone and substrate delivery as well as product removal. Because a high proportion of nutritive flow may elevate the set point for basal metabolism, a low proportion of nutritive flow in muscle at rest confers an evolutionary advantage, particularly when food is scarce. In addition, the proportion of flow that is carried by the non-nutritive routes at rest affords a flow reserve that can be switched to the nutritive route to amplify nutrient supply during exercise. Alternatively the non-nutritive route may allow flow to escape when active muscle contraction compresses its nutritive capillaries. Thus rhythmic oscillation of blood flow between the non-nutritive and nutritive networks may aid the muscle pump.

Increased metabolism of infused 1-methylxanthine by working muscle.

Exogenous substrates for capillary endothelial enzymes have potential as markers for changes in capillary recruitment (albeit nutritive flow). The metabolism of infused 1-methylxanthine (1-MX) to 1-methylurate (1-MU) by capillary endothelial xanthine oxidase of the constant-flow perfused rat hindlimb was shown previously to decrease with oxygen uptake (VO2) when nutritive flow was decreased. In the present study, the metabolism of 1-MX was investigated under conditions when VO2 and nutritive flow are known to increase during muscle contraction. The constant-flow red blood cell-perfused rat hindlimb at 37 degrees C was used with sciatic nerve stimulation, and perfusate samples from whole hindlimb and working muscles taken for analysis of oxygen, lactate, 1-MX and 1-MU. Flow to muscle was assessed separately using fluorescent microspheres and was found to increase 2.3-fold to the working muscles while flow to the non-working leg muscles decreased to compensate. The activity of xanthine oxidase of whole muscle extracts was not altered by contraction. Samples from the vein draining the working muscles, and microsphere measurements of flow, indicated increased VO2 (5.5-fold to 249.2 +/- 43.1 micromol h-1 g-1, P < 0.001), and 1-MX conversion (2.5-fold to 1.87 +/- 0.25 micromol h-1 g-1, P < 0.01) (SEM are shown). It is concluded that as 1-MX metabolism parallels VO2, this substrate may be a useful indicator of changes in capillary (nutritive) surface area in muscle.

Factorial validity of the Bulimia Test-Revised in adolescent boys and girls.

The present study examined the psychometric properties and principal components structure of the Bulimia Test Revised (BULIT-R; [Thelen, M.H., Farmer, J., Wonderlich, S. & Smith, M. (1991). A revision of the Bulimia Test: the BULIT-R. Psychological Assessment, 3, 119-124.]) using a sample of early adolescent males and females. Three hundred and six girls (mean age = 13.66; S.D. = 1.12) and 297 boys (mean age = 13.89: S.D. = 1.13) from grades 7-10 completed the BULIT-R as part of a larger study investigating disordered eating in early adolescence. In comparison to the 5 factors identified in adult female samples, the factor analysis identified four similar factors for adolescent boys and girls: bingeing, control, normative weight loss (dieting and exercise) and extreme weight loss behaviors (vomiting, diuretics and laxatives). The findings highlight similarities between boys and girls and differences in the factorial nature of the BULIT-R for adult and adolescent samples. The BULIT-R also demonstrated good reliability with adolescent samples and adequate concurrent validity with the DFT, DEBQ and binge eating as defined by the DSM-IV criteria. The emergence of bingeing and control as two distinct factors is an important distinction that needs to be considered when attempting to provide accurate incidence rates of binge eating and bulimic symptomatology in adolescents.