Asynchronous Forward Bounding for Distributed COPs

A new search algorithm for solving distributed constraint optimization problems (DisCOPs) is presented. Agents assign variables sequentially and compute bounds on partial assignments asynchronously. The asynchronous bounds computation is based on the propagation of partial assignments. The asynchronous forward-bounding algorithm (AFB) is a distributed optimization search algorithm that keeps one consistent partial assignment at all times. The algorithm is described in detail and its correctness proven. Experimental evaluation shows that AFB outperforms synchronous branch and bound by many orders of magnitude, and produces a phase transition as the tightness of the problem increases. This is an analogous effect to the phase transition that has been observed when local consistency maintenance is applied to MaxCSPs. The AFB algorithm is further enhanced by the addition of a backjumping mechanism, resulting in the AFB-BJ algorithm. Distributed backjumping is based on accumulated information on bounds of all values and on processing concurrently a queue of candidate goals for the next move back. The AFB-BJ algorithm is compared experimentally to other DisCOP algorithms (ADOPT, DPOP, OptAPO) and is shown to be a very efficient algorithm for DisCOPs.

Challenges in the diagnosis and management of Nocardia infections in lung transplant recipients

BACKGROUND

Nocardia infection occurs in 2.1-3.5% of lung transplant recipients, and may involve cavitary nodular pulmonary lesions, soft tissue infection, or other sites of dissemination. Nocardiosis can pose challenging clinical problems in the areas of diagnosis and treatment. Diagnostic delays may occur, and adverse reactions to therapy are common. This study reviews clinical and epidemiological aspects of nocardiosis in lung transplant recipients, with special attention to pitfalls in management. Clinicians should be alert for these possibilities in order to institute prompt therapy and to achieve successful outcomes.

METHODS

A retrospective cohort study was conducted of 577 lung transplant recipients from January 1991 to May 2007. Demographics, reason for transplant, recent rejection, time from transplantation, site of infection, hypogammaglobulinemia, and/or neutropenia shortly before onset, Pneumocystis jiroveci prophylaxis, Nocardia species, radiographic findings, extrapulmonary lesions, nature and duration of treatment, adverse reactions, and outcomes were recorded.

RESULT

Nocardia infection occurred in 1.9% (11/577). Mean onset was 14.3 months after transplant (range 1.5-39 months). N. asteroides was isolated in 55% (6/11). Emphysema was the most common reason for transplant (7/11, 64%). Six patients were receiving trimethoprim-sulfamethoxazole (TMP-SMX) prophylaxis at the time of diagnosis. Three patients had immune globulin G levels <400 mg/dL and 2 were neutropenic in the 3 months preceding diagnosis. Diagnosis was made by bronchoalveolar lavage (55%), skin abscess culture (18%), open lung biopsy (9%), pleural fluid (9%), and sputum culture (9%). Definitive diagnosis required a median of 9 days and a mean of 13.6 days (range 3-35 days) from the time of diagnostic sampling. Soft tissue lesions occurred in 3 and central nervous system involvement in 1 patient. Adverse reactions to therapy occurred in 9/10 (90%) of patients for whom information was available. Nocardia-related mortality occurred in 2/11 patients (18%).

CONCLUSIONS

Nocardiosis occurred in 1.9% of lung transplant recipients and was associated with a mean of nearly 2 weeks to diagnosis and frequent adverse effects on therapy. TMP-SMX prophylaxis on a thrice weekly basis did not prevent all episodes of nocardiosis. Despite utilization of protocol bronchoscopies with cultures for Nocardia, this organism remains a source of clinical complexity in the lung transplant population.

Safety and side effects of immediate instillation of apaziquone following transurethral resection in patients with nonmuscle invasive bladder cancer

PURPOSE

We studied the safety, tolerability and pharmacokinetics of a single immediate post-transurethral resection intravesical instillation of apaziquone for patients with nonmuscle invasive bladder cancer.

MATERIALS AND METHODS

Patients with cTa-T1, G1-G2 urothelial cell carcinoma of the bladder underwent transurethral resection of bladder tumor(s) followed by a single intravesical instillation of apaziquone 4 mg/40 ml for 1 hour within 6 hours of transurethral bladder tumor resection. Adverse events and safety parameters were assessed on days 8 and 15 after transurethral bladder tumor resection. Blood samples were drawn before and during the instillation for pharmacokinetic analyses. The first 10 patients with pTa-T1, G1-G2 nonmuscle invasive bladder cancer were also evaluated by cystoscopy 3 months after treatment to determine mucosal healing.

RESULTS

Of 20 patients receiving apaziquone 13 (65%) reported 35 adverse events, mostly grade 1 to 2. Eight patients (40%) reported 13 adverse events related to treatment, in particular dysuria, hematuria, bladder spasm, abdominal pain, asthenia and postoperative urinary retention. Three grade 3 and 1 grade 4 event(s) occurred, but these were considered unrelated to treatment. No other significant clinical changes were observed. Apaziquone and the active metabolite EO5a were not detected with pharmacokinetic analyses at any point of time. After 3 months no evidence of impaired mucosal healing was observed.

CONCLUSIONS

A single immediate post-transurethral bladder tumor resection instillation of apaziquone was well tolerated with an expected good safety profile. Apaziquone and its metabolite EO5a were not detected systemically with pharmacokinetic analyses. These results have lead to further study of a single immediate instillation of apaziquone.

Laparoscopic renal surgery in children

A total of 17 laparoscopic renal procedures was performed in children, including nephrectomy (10), nephroureterectomy (4), partial nephrectomy (2) and giant renal cyst excision (1). Patient age ranged from 4 months to 11 years (average age 34 months). The average operating time was 2 hours and 15 minutes, ranging from 1 hour 50 minutes to 2 hours 45 minutes. The usual period of hospitalization was 23 hours, with the longest being 36 hours for 2 patients. No complications ensued. Despite the decreased working space in children, laparoscopic renal surgery offers compelling advantages, including short hospitalization, less perioperative and postoperative pain, improved cosmesis, earlier return to normal unrestricted activities and early return to work for the parents. Methods to accomplish renal laparoscopic surgery safely in children are detailed.

Laparoscopic vesicoureteroplasty in children: initial case reports

OBJECTIVE

To determine the feasibility of performing laparoscopic vesicoureteroplasty in children.

METHODS

Two pediatric patients, a two-year-old boy and a five-year-old girl, underwent laparoscopic vesicoureteroplasty for vesicoureteral reflux. Operating time was two hours fifteen minutes and three hours fifteen minutes, respectively.

RESULTS

The reflux was successfully corrected without morbidity, and they required only short hospitalization (23 hours) and exhibited decreased peri- and post-operative pain as well as improved cosmesis.

CONCLUSIONS

These cases represent the first implementation of this technique in humans. We stress that this is a preliminary report and suggest that this technique deserves further study.

Laparoscopic seromyotomy (auto-augmentation) for non-neurogenic neurogenic bladder in a child: initial case report

An eight-year-old boy with lifelong urinary incontinence secondary to non-neurogenic neurogenic bladder underwent successful laparoscopic seromyotomy (auto-augmentation) with resultant cure of his incontinence. The ability to perform this laparoscopically with its seventy-minute operating time, decreased hospital stay, and improved cosmesis militates for its consideration before a standard augmentation is performed.

Percutaneous endoscopic implantation of Automatic Implantable Cardioverter/Defibrillator (AICD): an animal study of a new nonthoracotomy technique

The Automatic Implantable Cardioverter/Defibrillator (AICD) prevents death due to malignant ventricular arrhythmias but requires thoracotomy for the implantation of the preferred two-patch lead system. The purpose of this study was to develop and test a new percutaneous endoscopic method of the AICD lead implantation without the need for open chest surgery. A high resolution video endoscopy system and currently available endoscopic instrumentation were used to develop pleural-pericardial dissection technique in 7 pigs and to endoscopically implant custom-made AICD patches in 20 pigs. An examining 10 mm rigid endoscope inserted in the 6th intercostal space in the anterior axillary line provided direct visual control for endoscopic dissection of the parietal pleura from the pericardium, delivery, and implantation of the AICD patches. This was successfully carried out through two trocars (10 and 11 mm) inserted into the pleural-pericardial space via the subxyphoid approach in 18 of 20 pigs. Effective patch positioning was confirmed by attaining a defibrillation threshold of 20J or less in 13 pigs. Of those, three required lead polarity reversal, and three others required lead repositioning to lower defibrillation thresholds to 20J or less. In three pigs, defibrillation thresholds of 30J or higher were required. Defibrillation was unsuccessful in two pigs due to patch malfunction. The authors conclude that percutaneous endoscopy is a feasible method of AICD lead implantation.

Laparoscopic choledochoscopy: an effective approach to the common duct

With increasing acceptance of routine cholangiography during laparoscopic cholecystectomy (for confirmation of anatomy) there has been increased identification of common duct calculi. A technique of laparoscopic transcystic common duct stone extraction is described and early clinical results are presented. Successful stone extraction was accomplished in 39 out of 41 consecutive attempts by one surgical team. Two cases required choledochotomy. There were four complications including hyperamylasemia (2), minor wound infection (1), and incidental pneumothorax (1). Recommendations regarding safety and indications are presented. Initial evaluation suggests laparoscopic transcystic stone extraction is safe and effective.

Laparoscopic cholecystectomy: instrumentation and technique

Laparoscopic cholecystectomy is rapidly evolving as a therapeutic modality for the treatment of gallstone disease. The technical details of this procedure and the method by which the gallbladder is dissected and removed are critical to the safe, effective execution of the procedure. Our technique has been developed through extensive practice in porcine models and through experience with more than 250 patients. To perform laparoscopic cholecystectomy we employ a high-resolution video endoscopy system, two high-resolution color monitors, a high-flow CO2 insufflator, a 300 W Xenon light source, electrocautery and/or lasers, and an endoscopic suction-irrigation system. This equipment permits the surgeon to obtain a clear field of view within the abdomen. With these tools, appropriately designed for laparoscopic surgery, including a laparoscope, graspers, dissectors, cholangiography equipment, scissors, and clip appliers, the surgeon can remove the gallbladder without opening the abdomen. The procedure requires the induction of a CO2 pneumoperitoneum, insertion of four trocars, and placement of a grasping retractor to set the operative field. An additional retractor placed on Hartmann's pouch provides countertraction for dissection of the hilum. Careful dissection around the cystic duct and cystic artery with a combination of electrocautery and blunt dissection allows the surgeon to skeletonize the cystic duct and artery. After intraoperative cholangiography confirms the anatomy, the cystic artery and cystic duct are clipped and divided. Electrocautery or laser techniques can be used to perform retrograde dissection of the gallbladder from the liver bed and insure hemostasis. The gallbladder is detached and removed intact through the large trocars. This basic technique can be applied in a wide variety of patients with cholelithiasis. The surgeon proficient in this technique may apply it to a broad range of patients with gallbladder disease.