A New Technique for Percutaneous Nephrolithotomy Using Retrograde Ureteroscopy and Laser Fiber to Achieve Percutaneous Nephrostomy Access: The Initial Case Report.

Background: Percutaneous nephrolithotomy (PCNL) serves as the gold standard minimally invasive procedure to remove large renal stones. The puncture is made from the skin to the chosen calix under fluoroscopic guidance, although this remains a challenging technique. We describe the initial case of retrograde holmium laser acquired nephrostomy access. Case Presentation: In this study, we present the case of a 48-year-old woman with right renal colic with imaging revealing a 2.6 cm staghorn stone. With institutional approval, we performed a new technique utilizing retrograde access with a flexible ureteroscope and a holmium laser fiber to achieve nephrostomy access for PCNL in the prone position. With the ureteroscope confirmed in the desired calix, the ureteroscope and laser fiber were aimed and fired toward the flank and thus creating a subcostal nephrostomy tract. PCNL was then carried out per standard of care lithotripsy techniques utilizing the holmium laser. Conclusion: In this initial case, percutaneous retrograde laser access allowed for desired caliceal nephrostomy access under direct vision.

Ureteroscopic holmium laser-assisted retrograde nephrostomy access: a novel approach to percutaneous stone removal.

INTRODUCTION AND OBJECTIVES: Percutaneous nephrolithotomy remains a challenging procedure primarily due to difficulties obtaining access. Indeed, few urologists obtain their own access due to difficulties using a fluoroscopic or ultrasonic based antegrade puncture technique. Herein we report the first experience using holmium laser energy to obtain access in a retrograde fashion. METHODS: After a pretreatment week of tamsulosin 0.4 mg/day (one center only) and following a documented sterile urine, a total of ten patients underwent retrograde holmium laser-assisted endoscopic-guided nephrostomy access in a prone split leg position. RESULTS: In nine of ten patients, ureteroscopic guided, holmium laser access via an upper pole posterior calyx was achieved. In one patient, the laser tract could not be safely dilated and antegrade endoscopic and fluoroscopic guided access was performed. The mean operative time was 202 min; the mean fluoroscopy time was 32 s (6/9 cases). The mean pre-operative stone volume was 14,420 mm3. CT imaging on post-operative day 1 revealed 6/6 patients had residual stone fragments with total mean volume of 250 mm3 (96% reduction); there were no residual fragments in three patients who were evaluated with non-CT radiographic imaging (KUB). There was a single complication requiring angioembolization due to a subcapsular hematoma with associated secondary tearing of an inter-polar vessel remote from the nephrostomy site. CONCLUSIONS: Holmium laser-assisted endoscopic-guided retrograde access in a prone split-leg position was successfully performed at two institutions. The accuracy of nephrostomy placement and lessening of fluoroscopy time are two potential benefits of this approach.

Yawning reduces facial temperature in the high-yawning subline of Sprague-Dawley rats.

BACKGROUND: Yawning is a stereotyped behavior that enhances blood flow to the skull, and the resulting counterflow has been hypothesized as a mechanism for brain cooling. Studies have shown that yawns are strongly associated with physiological and pathological conditions that increase brain temperature, and that they are followed by equivalent decreases in brain temperature. However, measured reductions in cranial or facial temperatures following yawning have yet to be reported, to our knowledge. To accomplish this, we used a subline of Sprague-Dawley rats that yawn at a much greater rate (20 yawns/h) than do outbred Sprague-Dawley rats (2 yawns/h). RESULTS: Using an infrared camera, we effectively evaluated thermal changes in the cornea and concha of these rats before, during, and after yawns. The maximum temperature in both regions significantly decreased 10 s following yawns (concha: -0.3 °C, cornea: -0.4 °C), with a return to basal temperatures after 20 s. CONCLUSIONS: This study is the first clear demonstration of yawning-induced thermal cooling on the surface of the face, providing convergent evidence that this behavior plays a functional role in thermoregulation. As other studies have demonstrated that yawning is capable of reducing cortical brain temperature, our current data support the idea that yawning functions as a thermoregulator, affecting all structures within the head.

A systems-level analysis of perfect adaptation in yeast osmoregulation.

Negative feedback can serve many different cellular functions, including noise reduction in transcriptional networks and the creation of circadian oscillations. However, only one special type of negative feedback ("integral feedback") ensures perfect adaptation, where steady-state output is independent of steady-state input. Here we quantitatively measure single-cell dynamics in the Saccharomyces cerevisiae hyperosmotic shock network, which regulates membrane turgor pressure. Importantly, we find that the nuclear enrichment of the MAP kinase Hog1 perfectly adapts to changes in external osmolarity, a feature robust to signaling fidelity and operating with very low noise. By monitoring multiple system quantities (e.g., cell volume, Hog1, glycerol) and using varied input waveforms (e.g., steps and ramps), we assess in a minimally invasive manner the network location of the mechanism responsible for perfect adaptation. We conclude that the system contains only one effective integrating mechanism, which requires Hog1 kinase activity and regulates glycerol synthesis but not leakage.

Enhanced identification and exploitation of time scales for model reduction in stochastic chemical kinetics.

Widely different time scales are common in systems of chemical reactions and can be exploited to obtain reduced models applicable to the time scales of interest. These reduced models enable more efficient computation and simplify analysis. A classic example is the irreversible enzymatic reaction, for which separation of time scales in a deterministic mass action kinetics model results in approximate rate laws for the slow dynamics, such as that of Michaelis-Menten. Recently, several methods have been developed for separation of slow and fast time scales in chemical master equation (CME) descriptions of stochastic chemical kinetics, yielding separate reduced CMEs for the slow variables and the fast variables. The paper begins by systematizing the preliminary step of identifying slow and fast variables in a chemical system from a specification of the slow and fast reactions in the system. The authors then present an enhanced time-scale-separation method that can extend the validity and improve the accuracy of existing methods by better accounting for slow reactions when equilibrating the fast subsystem. The resulting method is particularly accurate in systems such as enzymatic and protein interaction networks, where the rates of the slow reactions that modify the slow variables are not a function of the slow variables. The authors apply their methodology to the case of an irreversible enzymatic reaction and show that the resulting improvements in accuracy and validity are analogous to those obtained in the deterministic case by using the total quasi-steady-state approximation rather than the classical Michaelis-Menten. The other main contribution of this paper is to show how mass fluctuation kinetics models, which give approximate evolution equations for the means, variances, and covariances of the concentrations in a chemical system, can feed into time-scale-separation methods at a variety of stages.

Mass fluctuation kinetics: capturing stochastic effects in systems of chemical reactions through coupled mean-variance computations.

The intrinsic stochastic effects in chemical reactions, and particularly in biochemical networks, may result in behaviors significantly different from those predicted by deterministic mass action kinetics (MAK). Analyzing stochastic effects, however, is often computationally taxing and complex. The authors describe here the derivation and application of what they term the mass fluctuation kinetics (MFK), a set of deterministic equations to track the means, variances, and covariances of the concentrations of the chemical species in the system. These equations are obtained by approximating the dynamics of the first and second moments of the chemical master equation. Apart from needing knowledge of the system volume, the MFK description requires only the same information used to specify the MAK model, and is not significantly harder to write down or apply. When the effects of fluctuations are negligible, the MFK description typically reduces to MAK. The MFK equations are capable of describing the average behavior of the network substantially better than MAK, because they incorporate the effects of fluctuations on the evolution of the means. They also account for the effects of the means on the evolution of the variances and covariances, to produce quite accurate uncertainty bands around the average behavior. The MFK computations, although approximate, are significantly faster than Monte Carlo methods for computing first and second moments in systems of chemical reactions. They may therefore be used, perhaps along with a few Monte Carlo simulations of sample state trajectories, to efficiently provide a detailed picture of the behavior of a chemical system.

Comparison of basic elements of human performance scores between urologists with various extents of experience.

BACKGROUND AND PURPOSE: An objective evaluation of innate ability and its ability to predict potential success as a surgical trainee is an appealing concept for the selection process of residency applications. The objective of this study was to evaluate whether basic elements of performance (BEP) could discriminate among resident applicants and urologists with various extents of surgical experience. SUBJECTS AND METHODS: One hundred forty-five participants were divided into four study groups: group A, 57 urology residency applicants to the 2002 and 2003 interview process; group B, 8 post-internship urology residents; group C, 19 urologists tested with BEP within 10 years of graduation from their residency training program; and group D, 61 urologists who had graduated from their residency training program more than 10 years prior to testing. The BEP measures consisted of 13 basic performance resources (BPR) including visual-information processing speed, visual-spatial immediate-recall capacity, and neuromotor channel capacity. RESULTS: The four study groups differed significantly in their mean age: group A=27.6 years, group B=29.1 years, group C=37.1 years, and group D=48.9 years (P<0.0005). There was essentially no significant difference between the groups with regard to immediate-recall memory, reaction time simple, or reaction time complicated. The younger participants (groups A and B) were faster than the older surgeons (groups C and D) (P<0.02). However, the older surgeons (groups C and D) were significantly more accurate than the younger groups (A and B) (P<0.0005). The only sex differences noted were in hand-grip strength and shoulder-strength scores, which were all higher in the men. CONCLUSIONS: There generally appears to be a lack of direct correlation between innate abilities and surgical experience. Urology resident applicants with no surgical experience and urology residents with limited surgical experience are faster but less accurate in innate skills testing than experienced practicing urologists.

Short-term impact of a robot-assisted laparoscopic prostatectomy 'mini-residency' experience on postgraduate urologists' practice patterns.

INTRODUCTION: To assist practising urologists acquire and incorporate robot-assisted laparoscopic prostatectomy (RALP) into their practice, a 5 day mini-residency (M-R) programme with a mentor, preceptor and potential proctor experience was established at the University of California, Irvine, Yamanouchi Center for Urological Education. The follow-up results from the initial 21 RALP M-R participants are presented. METHODS: Between September 2003 and September 2004, 21 urologists from six states and four countries underwent a RALP M-R. Each participant underwent 1:2 teacher:attendee instruction over a 5 day period, which included inanimate model skills training, animal/cadaver laboratory skills training and operating room observation experience. Participants were also offered a proctoring experience at their hospital if they so desired. A questionnaire survey was mailed 1-14 months (mean 7.2 months) following completion of the mini-residency and these results were tabulated and reviewed. RESULTS: A 100% response rate was achieved from the mailed questionnaires. The mean M-R participant age was 43 years (range 33-55 years). One-third of the M-R participants were practising in an academic environment. Most of the participants (55%) had no fellowship training. Of those with fellowship training (45%), three (15%) were in laparoscopy and three (15%) were in oncology; 25% of the participants were in large (>6 physicians), 25% in small (2-6 physicians) and 15% in solo practices; 70% of the participants were located in an urban setting. The majority of the participants (80%) had laparoscopic experience during residency training and had performed 20-60 laparoscopic cases prior to attending the M-R programme. Within 7.2 months after M-R (range 1-14 months), 95% of the participants were practising robot-assisted laparoscopic prostatectomy and 25% of the RALP M-R participants had also performed robotic-assisted laparoscopic pyeloplasty. Of the M-R participants, 38% availed themselves of the preceptor/proctor component of the programme; among these, 100% reported that they were performing RALP vs. only 92% of the MR participants who did not have a proctor experience. The 5 day length of the M-R was considered to be of satisfactory duration by 90% of the participants, while 1 participant considered it too brief and 1 considered it too long. All but one of the participants rated the M-R as a very or extremely valuable experience. All the M-R participants indicated that they would recommend this training programme to a colleague. CONCLUSIONS: A 5 day intensive RALP M-R course seems to encourage postgraduate urologists, already familiar with laparoscopy, to successfully incorporate robotic surgery into their practice. The take rate, or the percentage of participants performing robotic-assisted surgery within 14 months after M-R, was 95%. Continued follow-up will ultimately determine the long-term effectiveness of this 1 week intensive training programme for postgraduate urologists.

What happens to hemostatic agents in contact with urine? An in vitro study.

BACKGROUND AND PURPOSE: As the indications for topical hemostatic agents increase in urology, the question arises: what happens to these agents when they enter the urinary collecting system? To answer this question, we performed a series of in-vitro experiments mixing three hemostatic agents with normal and sanguineous urine. MATERIALS AND METHODS: Four commercially available topical hemostatic products: oxidized regenerated cellulose (Surgicel; Ethicon, Somerville, NJ), fibrin sealant (Tisseel VH Kit; Baxter Health Care Corporation, Irvine, CA), gelatin matrix hemostatic sealant (FloSeal; Baxter Health Care), and polyethylene glycol (CoSeal; Cohesion Technologies, Palo Alto, CA) were studied. Human urine (10 mL) was added to samples of each substance; this was done in triplicate. The 12 sample tubes were then capped and placed on a tube shaker at slow speed and 37 degrees C. Observations regarding consistency of the material were made at 6, 12, 24, 48, 72, 96, and 120 hours (5 days). Gelatin matrix hemostatic sealant was further tested in urine with various amounts of blood or blood clot; observations were again recorded out to 5 days. RESULTS: Surgicel maintained its solid form when it initially came in contact with urine, but over a period of 5 days, it transformed into a mucoid substance with visible free-floating fibers. It did not dissolve completely in urine within 5 days. Gelatin matrix was immediately transformed by urine into a fine colloidal suspension that did not change over the 5 days of the study. Fibrin glue, after mixing of the two components (fibrinogen and thrombin) directly in the urine, and polyethylene glycol immediately formed a solid clot at the bottom of the test tube on contact with the urine. When the mixture of fibrin sealant was allowed to form for 15 minutes and then added to urine, it again maintained a solid form. After 72 hours, the fibrin glue became a semisolid gelatinous plug. On analysis at 5 days, the fibrin sealant clot had transformed into a cohesive mucoid gel, and the polyethylene glycol clot had not changed. The gelatin matrix hemostatic sealant, when in contact with blood or blood clot, appeared to either become part of a clot or to remain in a colloidal suspension. At 5 days, all clots had dissolved to fine particulate suspensions, and the gelatin matrix appeared as a fine suspension. CONCLUSION: Fibrin glue and oxidized regenerated cellulose maintain a solid form when initially placed in direct contact with urine and then assume a semisolid gelatinous state, which is still present at 5 days. Polyethylene glycol forms a solid clot initially and does not change after 5 days. Only hemostatic gelatin matrix remained as a fine particulate suspension in both normal and sanguineous urine. The implications of these findings with regard to sealing the renal parenchyma or small violations of the collecting system after percutaneous or laparoscopic surgery await in-vivo testing.

Initial impact of a dedicated postgraduate laparoscopic mini-residency on clinical practice patterns.

BACKGROUND AND PURPOSE: Laparoscopic surgical techniques are difficult to master, especially for surgeons who did not receive this type of training during their residencies. We have established a 5-day mentor-preceptor- proctor-guided postgraduate "mini-residency" (M-R) experience in minimally invasive surgery. The initial results from the first 16 participants in the laparoscopic M-R modules are presented. PARTICIPANTS AND METHODS: On the first and the last day of the M-R, all participants underwent surgical skills testing using an open-surgery, standard laparoscopic, and robot-assisted laparoscopic format. A written examination was also administered on the last day. The influence of M-R on the participants' practice pattern was then assessed by a follow-up questionnaire survey 1 to 7 months after their attendance. RESULTS: Data from the first 16 participants were analyzed. Of note, the score was significantly improved for only one of the four tested laparoscopic skills (i.e., threading a suture through loops). Nonetheless, on the follow-up survey, of the 15 respondents, two laparoscopically naïve participants had performed laparoscopic nephrectomy, and of the eight participants who had prior renal-ablative laparoscopic experience, four had performed advanced reconstructive laparoscopic cases. CONCLUSIONS: A 5-day dedicated postgraduate M-R in laparoscopy appears to be helpful for urologists wishing to incorporate this surgical approach into their practices. The "take rate" among participants is initially at the 40% level, similar to what has been previously reported after a 1 to 2-day hands-on didactic laparoscopy course.

Fibrin glue-oxidized cellulose sandwich for laparoscopic wedge resection of small renal lesions.

PURPOSE: We present our experience with standard laparoscopic wedge resection of small renal tumors using a fibrin glue-oxidized cellulose sandwich for hemostasis. MATERIALS AND METHODS: From May 2002 to December 2003, 15 patients underwent laparoscopic wedge resection for a total of 15 nonhilar renal masses. Renal hilar clamping was performed in 1 patient and no sutures were placed. We used ultrasonic shears and an argon beam coagulator to resect and then coagulate the tumor bed. Tisseel (Baxter Corp., Deerfield, Illinois) was applied to the resection bed, followed by a layer of oxidized, regenerated cellulose (Surgicel, Ethicon, Somerville, New Jersey) and a final layer of Tisseel. RESULTS: Mean preoperative tumor size was 2.2 x 2.2 x 2.1 cm. Lesions were subdivided based on the percent of the lesion that extended beyond the renal parenchymal border on computerized tomography as exophytic-greater than 60% in 6 cases, endophytic-less than 40% in 4 and mesophytic-40% to 60% in 5. Mean operative time was 3.8 hours (range 3 to 5). Mean blood loss was 108 ml (range 20 to 300). No patient required blood transfusion. There was no significant difference in blood loss or change in creatinine among the endophytic, exophytic and mesophytic groups (150, 121 and 93 ml, and 0.03, 0.07 and 0.04 mg/dl, respectively). Margin status was negative in all cases (mean thickness 3.2 mm). Average hospital stay and time to the resumption of oral intake were 2.7 and 1.4 days, respectively. CONCLUSIONS: Small exophytic or mesophytic renal lesions can be safely excised laparoscopically without vessel clamping. Excellent hemostasis was achieved in each case with the newer hemostatic agents.

Comparison of guide wires in urology. Which, when and why?

PURPOSE: We compared and contrasted various guide wires with regard to their physical properties as they apply to their use for the access or coaxial passage of other catheters. MATERIALS AND METHODS: Certain 0.035-inch diameter guide wires were tested with regard to tip bending force, shaft bending force, pull force and tip puncture force, namely the Roadrunner PC and polytetrafluoroethylene (PTFE) wire guide (Cook Urological, Spencer, Indiana), Glidewire, Bentson type 15 cm flexible tip PTFE coated guide wire and Amplatz super stiff Urowire XF (Boston Scientific Microvasive, Miami, Florida), Bentson guide wire and Amplatz guide wire (Applied Medical, Rancho Santa Margarita, California) and the PTFE coated Bard guide wire (Bard Urological Division, Covington, Georgia). RESULTS: Regarding guide wires used for access, the Boston Scientific PTFE guide wire with a 15 cm flexible tip required the least amount of force to deflect the tip. Of the 3 cm flexible tip guide wires the Applied Bentson guide wire had the most flexible tip and the Bard guide wire had the stiffest flexible tip. The Boston Scientific Glidewire required the least amount of force to pull from a tortuous pathway and this guide wire also required the greatest force (4 times as much force as the other guide wires) to puncture the aluminum foil (p < 0.001), indicating the safety of its tip. Regarding axial rigidity for the coaxial passage of other catheters over a guide wire, the Boston Scientific Amplatz super stiff guide wire was significantly more resistant to bending than all of the other guide wires that we tested (p < 0.05). CONCLUSIONS: Brand name guide wires designed for the same purpose appear to differ markedly with regard to flexibility, lubricity and shaft stiffness. In general, floppy tip and nitinol based guide wires appear to be best used for access with an emphasis on tip flexibility and a low friction coating, while the stiffer shaft guide wires are selected for coaxial passage of catheters, stents and sheaths.

La controversia por la cultura en el DSM-IV / Cultural controversy in DSM-IV

El interés de este artículo es examinar el propósito explícito del DSM-IV de convertirse en una clasificación nosológica universal de las enfermedades mentales. Tal meta incluye un postulado sobre la aplicabüidad transcultural empírica del manual y un postulado sobre la existencia de "síndromes culturales psiquiátricos" (Culture-Bound Syndromes). Ambos son discutidos en el texto/ así como la polémica generada con relación a la extensión y la profundidad de los cambios que en relación con la cultura se introdujeron en el DSM-IV. El artículo se centra en un principio en la categoría de esquizofrenia y otros trastornos psicótícos. Luego se revisa el asunto de fondo de esta cuestión: la discusión sobre la índole de la enfermedad mental. Como conclusión se ofrece la idea de que el debate entre la posición biomédica y la posición de la construcción cultural y social de la enfermedad mental dista de estar zanjado