Pediatric robotic-assisted laparoscopic ureterocalycostomy: Salient tips and technical modifications for optimal repair.

Introduction: Ureterocalycostomy is a necessary option for renal salvage in cases where conventional reconstructions have failed or as a primary option in anatomic situations such as intrarenal pelvis, malrotated, or horseshoe kidney. The primary principle of this procedure is to allow for dependent drainage. Ureterocalycostomy is often difficult due to extensive scar tissue and may be complicated by bleeding in the setting of a normal functioning lower pole cortex, compared to thin renal cortex and poor renal function as seen in end-spectrum of the obstruction. Identification of a dependent calyx and hemostasis can be difficult when there is a normal cortical thickness. Though the vascular control of hilum is an option, we suggest some simple tips to avoid this step and optimize surgical results. We present our experience and salient technical tips with pediatric robotic-assisted laparoscopic ureterocalycostomy and provide a step-by-step video. Methods: Four patients underwent robotic-assisted laparoscopic ureterocalycostomy between the years 2012 and 2016 by a single surgeon. Perioperative outcomes measured included operative time, hospital stay, pain relief, degree of hydronephrosis on postoperative ultrasound at 3 months, and renal scintigraphy as needed. We describe the operative procedure and provide tips on identifying a dependent lower pole calyx with flexible nephroscopy and needle puncture, the use of harmonic scalpel for incision of the lower pole cortex, and anastomosis by pre-placement of interrupted sutures as the urothelium of the renal calyces is thin and friable. Results: Patients ranged in age between 11 months and 14 years old. Three of four patients had one prior pyeloplasty, and one patient had two prior pyeloplasties. Mean operative time (incision to closure) was 208 minutes. No Clavien-Dindo 30-day complications were encountered and no patients required blood transfusion. Anatomic success was reported in all patients with a mean follow-up of 4.46 years; however, one patient ultimately required nephrectomy despite patent anastomosis, which would not drain due to a capacious pelvis. Conclusions: Robotic-assisted laparoscopic ureterocalycostomy is feasible in re-operative cases with extensive scaring and in patients with normal lower pole renal cortex. We offer tips to allow for safe and proficient performance of this procedure.

Intra- and Extra-articular Features of Temporomandibular Joint Ankylosis in the Cat (Felis catus).

Temporomandibular joint (TMJ) ankylosis is an uncommon clinical entity in human and veterinary medicine. However, the condition is severely debilitating and is life-limiting if not treated. This study sought to characterize the intra- and extra-articular features of naturally occurring TMJ ankylosis in cats. TMJs from client-owned cats (n = 5) that underwent bilateral TMJ gap arthroplasty were examined and compared with TMJs from healthy, age-matched feline cadavers (n = 2) by cone-beam computed tomography (CBCT), micro-computed tomography (µCT) and histologically. Features of bilateral intra- and extra-articular ankylosis compounded by degenerative joint lesions were identified radiographically and histologically in all affected cats. Features of TMJ 'true' ankylosis included variable intracapsular fibro-osseous bridging, degeneration of the disc and the articular surfaces, narrowing of the joint space and flattening of the condylar process of the mandible. Extra-articular features of TMJ ankylosis included periarticular bone formation and fibro-osseous bridging between the mandible, zygomatic arch and coronoid process. In addition, subchondral bone loss or sclerosis, irregular and altered joint contours and irregularly increased density of the medullary bone characterized the degenerative changes of the osseous components of the TMJ. Complex radiological and histological features of both ankylosis and pseudoankylosis were identified that clinically manifested in complete inability to open the mouth.

Bubbles in noodle dough: Characterization by X-ray microtomography.

Bubbles, found in a huge variety of food products, are known to afford desirable quality attributes, especially those related to texture, mouthfeel and taste. However, the presence of bubbles and their effects on wheat flour noodles is an aspect that has been, until now, largely overlooked, despite the positive and negative connotations of bubbly inclusions on Asian noodle quality. X-rays from a synchrotron source (Biomedical Imaging and Therapy facility at the Canadian Light Source) were used to rapidly and non-destructively acquire tomographic images of noodle dough. Appropriate image analysis protocols were used to determine the bubble size distribution, the orientation of bubbles, and their position within the dough sheet. The effect of processing (one or multiple lamination steps) on bubble properties in the dough that was subsequently sheeted (gradual elongation and reduction in thickness) was investigated. Bubble size distributions, well captured by lognormal distribution function, showed that the lamination process induced bubble entrapment and reduction in bubble size. Bubbles were found to be flat, elongated and oriented in the sheeting direction, this effect being less for doughs laminated ten times (90° rotations between lamination steps). Interestingly, a gradient in concentration of bubbles within the dough sheet was found from the noodle core to the sheet edges. Aging effects were also apparent. This first non-destructive study of bubbles in wheat-flour noodle dough provides a more complete knowledge of the dough sheet's internal structure, and how it originates via processing, and this has repercussions on the overall quality of Asian noodles.

The Temporomandibular Joint of the Domestic Dog (Canis lupus familiaris) in Health and Disease.

This study aimed to characterize the histological, biomechanical and biochemical properties of the temporomandibular joint (TMJ) of the domestic dog in health and disease. In addition, we sought to identify structure-function relationships and to characterize TMJ degenerative lesions that may be found naturally in this species. TMJs (n = 20) from fresh cadaver heads (n = 10) of domestic dogs were examined macroscopically and microscopically and by cone-beam computed tomography. The TMJ discs were evaluated for their mechanical and biochemical properties. If TMJ arthritic changes were found, pathological characteristics were described and compared with healthy joints. Five (50%) dogs demonstrated macroscopically normal fibrocartilaginous articular surfaces and fibrous discs and five (50%) dogs exhibited degenerative changes that were observed either in the articular surfaces or the discs. In the articulating surfaces, these changes included erosions, conformational changes and osteophytes. In the discs, degenerative changes were represented by full-thickness perforations. Histologically, pathological specimens demonstrated fibrillations with or without erosions, subchondral bone defects and subchondral bone sclerosis. Significant anisotropy in the TMJ discs was evident on histology and tensile mechanical testing. Specifically, the discs were significantly stiffer and stronger in the rostrocaudal direction compared with the mediolateral direction. No significant differences were detected in compressive properties of different disc regions. Biochemical analyses showed high collagen content and low glycosaminoglycan (GAG) content. No significant differences in biochemical composition, apart from GAG, were detected among the disc regions. GAG concentration was significantly higher in the central region as compared with the caudal (posterior) region. The TMJ of the domestic dog exhibits similarities, but also differences, compared with other mammals with regards to structure-function relationships. The TMJ articular surfaces and the disc exhibit degenerative changes as seen in other species, including perforation of the disc as seen in man. The degenerative changes had greater effects on the mechanical properties compared with the biochemical properties of the TMJ components. Translational motion of the TMJ does occur in dogs, but is limited.

Mesiodistal root angulation using panoramic and cone beam CT.

OBJECTIVE: To determine if the panoramic projection can accurately determine mesiodistal root angulations. MATERIALS AND METHODS: A plaster study model of the dentition of each of five patients was prepared. A radiographic stent containing radiopaque markers was fabricated for each of the models. Panoramic and cone beam computed tomography (CBCT) scans were taken on each patient with the radiographic stent seated on the dentition. Root angulations for each of the radiographic images were measured and compared. RESULTS: Root angulation was measured by three independent individuals and good reliability between measurements was demonstrated. Compared to plaster model measurements (the gold standard), the CBCT scan produced very accurate measurements of root angulation. Compared to CBCT images, panoramic projections did not provide reliable data on root angulation. CONCLUSION: Panoramic images did not accurately represent the mesiodistal root angulations on clinical patients.

Contractile properties of cat skeletal muscle after repetitive stimulation.

The isometric and force-velocity properties of the fast-twitch flexor digitorum longus (FDL) and slow-twitch soleus muscles were investigated immediately after and during recovery from a fatiguing stimulus regime (40 Hz for 330 ms every second for 180 s) in the anesthetized cat. The amplitude of the isometric twitch of FDL was unaffected but in soleus it remained depressed for much of the recovery period. Immediately after stimulation the twitch time to peak of FDL increased to 140% of the control (prefatigue) value and then reverted to control values. The maximum isometric tetanic tension (Po) developed by FDL was reduced to 67% of control values immediately after the stimulus regime, whereas soleus declined to 93% of control. Recovery of maximum force development was achieved after 45 min in FDL and after 15 min in soleus. The maximum speed of shortening of FDL was reduced to 63% of control values immediately after fatigue; despite some recovery within the first 30 min, it remained depressed during the remainder of the recovery period (up to 300 min). Maximum speed of shortening was unaltered in soleus. The a/Po value transiently increased to 176% of control values in FDL immediately after the fatigue regime but promptly returned to control values. Force-velocity properties of soleus were not affected by the stimulus regime. It is concluded that in FDL changes in the maximum speed of shortening and maximum isometric tension as a result of the stimulus regime are attributable to changes in the intrinsic behavior of cross-bridges and the metabolic status of the fibers, particularly in the fast-twitch fatigue-resistant fibers.

Force-velocity properties of fatigue-resistant units in cat fast-twitch muscle after fatigue.

The isometric and force-velocity properties of an identified and uniform population of fast-twitch, fatigue-resistant (FR) fibers within the flexor digitorum longus (FDL) muscle were investigated before, immediately after, and during recovery from a fatiguing repetitive isometric stimulus regime (40 Hz for 330 ms every s for 180 s) in the anesthetized cat. It was necessary to determine the smallest fraction of muscle that had the same force-velocity properties as the whole muscle. This was approximately 15% for FDL; if the fraction was less, the maximum speed of shortening was depressed and the a/Po value increased. Motor units were enlarged by partial denervation of the muscle, causing the intact motoneurons to sprout and incorporate more muscle fibers; FR units showed the greatest increase. Immediately after the fatigue regime, maximum isometric tetanic tension declined to 67% but subsequently recovered to 90% of the control value by the end of the 60-min recovery period. Maximum speed of shortening dropped to 71% of the control but after 30 min had recovered and did not differ significantly from control values. It is concluded that the capacity for recovery from fatigue is greater for FR units than for a whole muscle, which also contains fast-fatiguable units, and that the mechanisms involved in the recovery of the maximum isometric tension and maximum speed of shortening are independently regulated.

Comparison of two noninvasive techniques for estimating cardiac output during exercise.

This study presents the comparison of two different noninvasive techniques for the estimation of cardiac output (Q). The two techniques used were transthoracic impedance plethysmography (Z) and the indirect Fick CO2 rebreathing (RB) method. Paired estimates of Q were made on 60 different male subjects at rest and during graded increments of work on a cycle ergometer. The mean resting Q as measured by the Z technique (COZ) was 7.46 +/- 0.35 and 5.96 +/- 0.43 l/min using the RB (CORB) technique. At 200 W the mean COZ was 18.67 +/- 0.72 l/min and the CORB was 23.73 +/- 0.84 l/min. Both the techniques were linearly correlated (R) with O2 consumption; i.e., RZ = 0.752, RRB = 0.855. The difference between these two R values is statistically significant (P less than 0.001). A linear relationship was found between the Z and RB techniques at all work loads (R = 0.75). This study suggests that both techniques are equally as reliable over a large range of work loads, with the Z technique being the simplest and most efficient to implement. It was also found that lung volume had no effect on the calculated COZ.

A three-dimensional investigation of temporomandibular joint loading.

A mathematical model of the muscle groups applied to the human mandible is developed to study the forces developed on the condyles during maximum unilateral occlusion. The results show that the reaction forces are in approximately a 2:1 ratio with the balancing side condyle carrying the greater load. Furthermore, the direction in which these condylar reactions occur is presented.

Isolation of hypoxanthine phosphoribosyltransferase-defective mutants in Chinese hamster V79 cells by tritium suicide.

Tritium suicide was shown to be a highly efficient method for isolating mutants defective in hypoxanthine incorporation in the Chinese hamster lung cell line V79. The tritium suicide procedure consisted of 3 kill cycles. Survivors of one kill cycle were used for the next kill cycle. The kill cycles involved incorporation of [3H]hypoxanthine for 5 or 10 min, followed by storage of 3H-labelled cells at -70 degrees C for 4-10 days. 12 clones that survived the 3rd kill cycle were tested for incorporation of [3H]hypoxanthine and all were found to be defective. At lest 6 of the clones have defective hypoxanthine phosphoribosyltransferase (HPRT) activity. One mutant, H19, chosen for further characterization, had HPRT with a 13-fold elevation in apparent Km for phosphoribosylpyrophosphate (PRPP). Thin-layer chromatography of cell extracts showed that this mutant was incapable of converting intracellular hypoxanthine to IMP or to other purine metabolites. In addition, H19 as resistant to 6-thioguanine.