Blocking S-adenosylmethionine synthesis in yeast allows selenomethionine incorporation and multiwavelength anomalous dispersion phasing

Saccharomyces cerevisiae is an ideal host from which to obtain high levels of posttranslationally modified eukaryotic proteins for x-ray crystallography. However, extensive replacement of methionine by selenomethionine for anomalous dispersion phasing has proven intractable in yeast. We report a general method to incorporate selenomethionine into proteins expressed in yeast based on manipulation of the appropriate metabolic pathways. sam1(-) sam2(-) mutants, in which the conversion of methionine to S-adenosylmethionine is blocked, exhibit reduced selenomethionine toxicity compared with wild-type yeast, increased production of protein during growth in selenomethionine, and efficient replacement of methionine by selenomethionine, based on quantitative mass spectrometry and x-ray crystallography. The structure of yeast tryptophanyl-tRNA synthetase was solved to 1.8 A by using multiwavelength anomalous dispersion phasing with protein that was expressed and purified from the sam1(-) sam2(-) strain grown in selenomethionine. Six of eight selenium residues were located in the structure.     

Laparoscopic partial nephrectomy with clamping of the renal parenchyma: initial experience

OBJECTIVES: Partial nephrectomy by laparoscopy offers patients conservative surgery and a mini-invasive approach; however, clamping of the renal pedicle and the induced warm ischaemia can damage the renal parenchyma. We present a technique of laparoscopic partial nephrectomy with haemostasis obtained by clamping of the renal parenchyma. METHODS: The procedure was performed by an intraperitoneal or a retroperitoneal approach. After a working space is created by pneumodissection, Gerota's fascia is incised and the kidney convexity is dissected. An endoscopic Satinsky clamp is inserted percutaneously through a 1-cm incision. The renal parenchyma is clamped and the tumour is excised in a bloodless field. The cut renal parenchyma is coated with biologic glue. RESULTS: Five patients with elective indications were operated. Mean age was 67.8 yr and mean tumour diameter 3.06 cm. One lesion was located at the upper pole and four at the lower pole. Mean preoperative serum creatinine level was 10.9 mg/l. Postoperative serum creatinine level was unchanged. Mean operative time was 238 min. There was no conversion. Mean blood loss was 250 ml; no transfusions were necessary. The collecting duct system was repaired in one patient. No complication was noticed. Resection margins were tumour free in all cases. Final pathologic examination revealed clear cell carcinoma in three cases and angiomyolipoma and oncocytoma in one case each. CONCLUSION: Laparoscopic partial nephrectomy with clamping of the renal parenchyma can be performed in selected patients with peripherally placed tumours. The procedure avoids warm ischaemia of the normal parenchyma while allowing the surgeon to operate in an almost bloodless field. This initial experience in five patients should be validated in a larger series.     

Tumour Necrosis Is an Indicator of Aggressive Biology in Patients with Urothelial Carcinoma of the Upper Urinary Tract

Background

Prognostic factors after radical nephroureterectomy (RNU) for upper tract urothelial carcinoma (UTUC) are inconclusive, because most data in the literature have been obtained from small series.

Objective

To assess the association of tumour necrosis with cancer recurrence and survival in a large international series of patients treated with RNU.

Design, setting, and participants

Data were collected from 1425 patients treated with RNU at 13 centres and combined into a relational database. Pathologic slides were re-reviewed by genitourinary pathologists according to strict criteria. Extensive tumour necrosis was scored as >10% of the tumour area.

Intervention

Patients underwent either open or laparoscopic RNU. Lymph node dissection was performed in the presence of enlarged nodes.

Measurements

Recurrence was defined as tumour relapse in the operative field, lymph node (LN) metastasis, and/or distant metastases. Bladder recurrences were not considered. Associations of extensive tumour necrosis with recurrence-free survival and cancer-specific survival were evaluated by univariate and multivariate analyses.

Results and limitations

Extensive tumour necrosis was observed in 364 patients (25.5%) and was associated with advanced tumour stage, high tumour grade, sessile architecture, lymphovascular invasion (LVI), concomitant carcinoma in situ, and LN metastasis (p < 0.0001 each). Extensive tumour necrosis was independently associated with disease recurrence and survival (p = 0.037 and p = 0.046, respectively) after adjusting for the effects of pathologic stage, grade, LVI, and LN status. The addition of extensive tumour necrosis to a base model comprising standard pathologic predictors marginally improved its predictive accuracy for both cancer-specific recurrence (1.5%) and survival (1.4%).

Conclusions

Extensive tumour necrosis is an independent predictor of clinical outcomes in patients who undergo RNU for UTUC. Assessment of tumour necrosis may help to identify patients who could benefit from multimodal therapy after RNU in the future. Evaluation of extensive tumour necrosis should be part of standard pathologic reporting.     

Treatment with sunitinib enabled complete resection of massive lymphadenopathy not previously amenable to excision in a patient with renal cell carcinoma

We present a case of previously unresectable lymphadenopathy in a patient with renal cell carcinoma treated with sunitinib. Complete resection of a 15-cm left renal cell carcinoma was initially impossible due to massive retroperitoneal disease and encasement of the great vessels and mesenteric vessels. Residual retroperitoneal disease from a radical nephrectomy was treated with the oral, multitargeted receptor tyrosine kinase inhibitor, sunitinib. Tumour shrinkage following five cycles of treatment allowed uncomplicated complete resection of the lymphadenopathy. Follow-up after 6 mo showed no evidence of disease recurrence.     

Langerhans cell histiocytosis revealed by painful hip: A case report

Langerhans cell histiocytosis is a rare disease in childhood. It has a very polymorphous clinical expression, ranging from a single bony disease to a multisystemic disease involving vital organs. Prognosis has been improved by use of chemotherapy. We report a 2-year-old girl with multifocal Langerhans cell histiocytosis of bone and skin, revealed by a pain of the left hip and a limp trailing from 2 months. The diagnosis has been established by histological exam. The patient received chemotherapy and steroids. Outcome was favourable over 6-month follow-up. Trailing limp should evoke diagnosis of Langerhans cell histiocytosis. Skin biopsy should be preferred to a bone biopsy because of its safety.