A RAC-GEF network critical for early intestinal tumourigenesis.

RAC1 activity is critical for intestinal homeostasis, and is required for hyperproliferation driven by loss of the tumour suppressor gene Apc in the murine intestine. To avoid the impact of direct targeting upon homeostasis, we reasoned that indirect targeting of RAC1 via RAC-GEFs might be effective. Transcriptional profiling of Apc deficient intestinal tissue identified Vav3 and Tiam1 as key targets. Deletion of these indicated that while TIAM1 deficiency could suppress Apc-driven hyperproliferation, it had no impact upon tumourigenesis, while VAV3 deficiency had no effect. Intriguingly, deletion of either gene resulted in upregulation of Vav2, with subsequent targeting of all three (Vav2-/- Vav3-/- Tiam1-/-), profoundly suppressing hyperproliferation, tumourigenesis and RAC1 activity, without impacting normal homeostasis. Critically, the observed RAC-GEF dependency was negated by oncogenic KRAS mutation. Together, these data demonstrate that while targeting RAC-GEF molecules may have therapeutic impact at early stages, this benefit may be lost in late stage disease.

Wnt ligands influence tumour initiation by controlling the number of intestinal stem cells.

Many epithelial stem cell populations follow a pattern of stochastic stem cell divisions called 'neutral drift'. It is hypothesised that neutral competition between stem cells protects against the acquisition of deleterious mutations. Here we use a Porcupine inhibitor to reduce Wnt secretion at a dose where intestinal homoeostasis is maintained despite a reduction of Lgr5+ stem cells. Functionally, there is a marked acceleration in monoclonal conversion, so that crypts become rapidly derived from a single stem cell. Stem cells located further from the base are lost and the pool of competing stem cells is reduced. We tested whether this loss of stem cell competition would modify tumorigenesis. Reduction of Wnt ligand secretion accelerates fixation of Apc-deficient cells within the crypt leading to accelerated tumorigenesis. Therefore, ligand-based Wnt signalling influences the number of stem cells, fixation speed of Apc mutations and the speed and likelihood of adenoma formation.

Effects of posture on gastric emptying and satiety ratings after a nutritive liquid and solid meal.

To study the effects of posture and meal structure on gastric emptying and satiety, nine women ingested tomato soup and then immediately or 20 min later an egg sandwich, when seated and when supine. The lag time was not different, but the half-emptying time of the sandwich was 32% longer (P < 0.01) and the emptying rate after the lag phase was 39% slower (P < 0.01) when the subjects were supine than when they were seated. The half-emptying time of the soup was 50% longer (P < 0.01) when the subjects were supine and ingested the soup immediately before the sandwich than in the other three conditions. Postprandial hunger ratings recovered more slowly (P < 0.01) when the subjects ingested the soup 20 min before the sandwich than when they ingested the soup immediately before the sandwich. These results suggest that posture did not affect the intragastric distribution of the sandwich but affected propulsion of the meal into the intestine and that postprandial satiety was enhanced by the cumulative effect over time of a 20-min "head start" in stimulation of intestinal receptors by emptying of the soup.

Use of diuretic renogram in evaluation of patients before and after endopyelotomy.

OBJECTIVES: Endopyelotomy is a widely accepted alternative in the treatment of ureteropelvic junction (UPJ) obstruction, with success rates between 63% and 88%. However, various methods have been used to evaluate patients with UPJ obstruction, making it difficult to compare results. Diuretic renography has the potential to unify the evaluation if performed in standard ways. In this report, we present a standardized protocol for diuretic renography. METHODS: Nineteen endopyelotomies were performed by one surgeon (E.B.K.) at our institution. The 16 patients were evaluated with technetium 99m MAG-3 diuretic renography. The presence or absence of obstruction was classified according to the differential renal function, time activity curves, and Tmax to T 1/2max time. Three patients had a postoperative Whitaker's test. RESULTS: Eight patients had pre- and postoperative diuretic renograms at our institution. This group was stratified by their differential renal function. Among 4 patients with differential renal function greater than 35%, 3 of 4 showed progressive improvement in renal function postoperatively, 4 of 4 had a Tmax to T 1/2max time less than 10 minutes, and 3 of 4 ha d unobstructed time activity curves. Five patients had postoperative renograms only. Of these 5 patients, 4 had differential renal function greater than 35% and 3 of 5 had normal-appearing curves and normal Tmax to T 1/2max time. Three patients required a second endopyelotomy and 2 of these underwent a dismembered pyeloplasty. CONCLUSIONS: Standardized diuretic renography should be used as an objective test for the evaluation of patients with UPJ obstruction. The successful outcome of an endopyelotomy depends on the preoperative renal function of the involved kidney. Whitaker's test may be used for equivocal cases.

Contribution of gastric and postgastric feedback to satiation and satiety in women.

Two parallel preload studies were conducted to determine the relative contributions of inhibitory feedback from the stomach and intestine to satiation (meal termination) and postprandial satiety. In the Gastric Emptying Study, five normal-weight women each ingested an egg sandwich (307 kcal) (1) immediately after a tomato soup preload (120 kcal), (2) 20 min after a tomato soup preload, and (3) with no preload. There was 125 g more of soup in the stomach when subjects began ingesting the sandwich immediately compared to 20 min after the soup, and the emptying of the sandwich was delayed when it was ingested immediately but not 20 min after the soup. The lag times for emptying of the sandwich were 76.5 (69.1-82.4), 47.2 (20.1-67.7), and 42.4 (17.8-65.1) min for the three conditions, respectively, p < 0.05. In the Food Intake Study, 16 normal-weight women ate significantly less (p < 0.01) in test meals offered immediately (978+/-246 kcal) and 20 min (1027+/-298 kcal) after the soup preload than in a test meal with no preload (1151+/-279 kcal). Despite the different amounts of soup in the stomach, subjects' test-meal intake in the two preload conditions was not significantly different. Subjects' fullness ratings following the preloads and the test meals were not different among the treatment conditions. The results suggest that feedback from neither the gastric nor the postgastric compartment is primary in determining meal size and postprandial satiety. Instead, signals from gastric and postgastric sources are combined to determine meal size and postprandial satiety.

Selective tumor irradiation by infusional brachytherapy in nonresectable pancreatic cancer: a phase I study.

PURPOSE: Selective high-dose radiation of solid tumors has been a goal of radiation oncology. The physiological barriers of solid tumors (high interstitial tumor pressure, reduced tumor vascularity, and poor perfusion) have been major barriers in achieving significant tumor dose of systemically infused radioconjugates. Direct tumor infusional brachytherapy overcomes these barriers and leads to selective high tumor doses. METHODS AND MATERIALS: The development of interstitial tumor infusion of macroaggregated albumin (MAA) followed by colloidal chromic phosphate 32P has overcome solid tumor obstacles in 47 patients with nonresectable pancreatic cancer in a Phase I dose escalation study. The colloidal 32P infusion was followed by external radiation and five fluorouracil. RESULTS: Of the 28 patients with cancer limited to the pancreas, 15 of 16 patients retained 86-100% (mean 96%) of the infused colloidal 32P isotope. While the other 12 patients had partial shunting to the liver, shunting to the liver was due to high interstitial resistance with tumor dose deposition of 17-88% (mean 52 %). Of the 19 patients with metastatic pancreas cancer, colloidal 32P tumor deposition ranged from 22 to 100% of the infused dose (mean 79%). The less than optimal tumor deposition led to our increasing the MAA from 600,000 to 1.5-2.5 million particles. Interstitial dexamethasone 2 mg and later 4 mg was infused first and prevented liver shunting by somehow reducing tumor resistance. The median survival in 28 Phase I patients with nonresectable pancreas cancer without metastasis, was 12 months. No significant toxicity occurred when treatment was limited to two infusions with as much as 30 mCi each. The maximum tumor dose was 17,000 Gy (1.700,000 cGy). In 19 nonresectable pancreatic cancer patients with metastasis, a 6.9 months median survival was observed. CONCLUSIONS: Infusional brachytherapy is an outpatient procedure that delivers high-dose radiation selectively to pancreatic cancer. Results of the Phase I study in nonresectable pancreas cancer has led to a national multiinstitutional Phase II trial.

Preliminary experience of infusional brachytherapy using colloidal 32P.

In the past, we have clinically evaluated radiolabelled antibodies in Hodgkin's disease and hepatocellular cancer. Increased tumour pressure, reduced vascularity and poor diffusion has limited significant radiolabelled antibody tumour dose deposition. Using intratumoural infusion of macroaggregated albumin to blockade exiting vasculature followed by colloidal chromic 32Phosphorous, we have been able to achieve 75% to 100% tumour dose deposition by interstitial tumour infusion under computerised tomographic guidance. Phase I studies in a variety of solid tumours indicate extremely high doses may be achieved without toxicity (i.e. non-resectable pancreas 900,000 cGy to 1.7 million cGy) with tumour control and remission. This is a review of those studies and how the technique was applied.

Quantitative bremsstrahlung single photon emission computed tomographic imaging: use for volume, activity, and absorbed dose calculations.

PURPOSE: To perform bremsstrahlung single photon emission computed tomographic (SPECT) imaging using 32P chronic phosphate for volume and activity quantitation to calculate absorbed dose estimates. METHODS AND MATERIALS: Seven cancer patients enrolled in clinical Phase I therapeutic protocols were injected with 2.5 million particles of macroaggregated albumin, followed by colloidal 32P chromic phosphate by direct interstitial injection into the tumor-bearing region under computed tomographic (CT) guidance. SPECT images were obtained in these patients. The patient body contour was defined through the use of two externally placed Compton backscatter 99mTc sources. A computer algorithm was written to facilitate region-of-interest volume and activity determination on the reconstructed SPECT slices based on a fixed threshold method. Three sequential SPECT studies were acquired in two of these patients, to determine the accuracy of activity quantitation for bremsstrahlung SPECT studies using Chang's postprocessing method of attenuation compensation with a computer-generated body contour based on the Compton backscatter sources, and an experimentally measured effective linear attenuation coefficient for 32P. The serial data in these two patients were used to calculate absorbed dose estimates. RESULTS: The 99mTc backscatter sources enabled the patient body outline to be clearly visualized in all the transaxial reconstructed slices and did not contribute significant counts to the patient 32P counts. The calculated activities from the SPECT studies were within 7.8% of the administered 32P activity. The two calculated patient absorbed doses were 4.2 x 10(3) Gy and 5.9 x 10(3) Gy for injected activities of 736 MBq and 920 MBq, respectively. CONCLUSION: We conclude that accurate quantitative bremsstrahlung SPECT imaging, for the case of high contrast well-localized activity distributions, with a commercially available postprocessing attenuation correction algorithm, can be performed in a clinical setting. Entirely SPECT-based measurements can be used to generate absorbed dose estimates.

A new method for delivering radioactive cytotoxic agents in solid cancers.

PURPOSE: Therapeutic agents such as monoclonal antibodies, radiopharmaceuticals, and radioactive growth factors are limited in effectiveness due to the inability to deposit significant quantities of the agents and for limited periods of time in solid cancer. A new technique based on knowledge of the pathophysiology of solid tumors allows for significant concentration of these agents to accumulate and for a prolonged period of time, thus allowing interaction with the tumor for potentially increased effectiveness. METHODS AND MATERIALS: Three agents have been studied: 131I antiferritin monoclonal antibody, colloidal 32P chromic phosphate, and 131I transferrin. The time required for maximal tumor uptake was determined in vitro in tissue culture and was 10 min, 25 min, and 40 min, respectively. The new method of in vivo tumor infusion consisted of a direct intratumoral injection of macroaggregated albumin (MAA) 10,000 particles, followed by the radioactive agents under study. Tumors were infused in vivo using the new technique and compared to intratumoral infused controls. In the instance of radiolabeled antiferritin antibody, intraperitoneal administration and intratumoral infusion were compared to the new technique. In the other two instances, intratumoral infusion was compared to the new method. RESULTS: In all instances the direct vascular blockade caused by MAA led to greater deposition of the agent under study for at least 24 h. These results were clinically applied with MAA followed by 32P colloidal chromic phosphate and were consistent with the experimental findings. CONCLUSION: A new technique is described that may be carried out in the experimental laboratory and clinic by direct tumor infusion of macroaggregated albumin (MAA), followed by other radioactive agents that will remain localized in solid cancers and will allow for high tumor dose deposition for potentially increased therapeutic efficacy.

Tc-99m-HMPAO leukocyte scintigraphy for the diagnosis of osteomyelitis in diabetic foot infections.

The diagnosis of osteomyelitis in the presence of soft tissue infection and neuropathic bone changes is often difficult in the diabetic foot. Previous attempts at scintigraphic diagnosis included Tc-99m methylene diphosphonate, Gallium-67 citrate and Indium-111 autologous leukocytes (WBCs). A new agent recently available, Technetium-99m-HMPAO labeled white blood cells, shows promise as a scintigraphic agent superior to other agents for this purpose. The authors discuss this agent and present a case report as a preliminary study.

Use of indium-111-labeled white blood cells in the diagnosis of diabetic foot infections.

The diagnosis of bone infection in the patient with nonvirgin bone is a diagnostic dilemma. This is especially true in the diabetic patient with a soft tissue infection and an underlying osteoarthropathy. The authors present a retrospective study using the new scintigraphic technique of indium-111-labeled white blood cells as a method of attempting to solve this diagnostic dilemma.

Comprehensive scrotal flow and scan technique for detection of varicoceles.

We describe a noninvasive modified radionuclide technique, the "comprehensive scrotal flow and scan," for the detection of varicoceles. The procedure utilizes in-vivo-labeled pyrophosphate red blood cells and 99mTc-pertechnetate as a blood pool scanning agent. The procedure includes an immediate flow study along with early and delayed static images, both in the upright and supine position. These studies were examined by visual inspection and by computer analysis. Data were obtained from 50 patients and 8 control subjects. The technique demonstrated a 91.1 per cent sensitivity when compared to physical examination and an 84.6 per cent sensitivity when compared to venography from patients with subclinical or poorly palpable varicoceles.

Scintigraphic detection of prosthetic joint and soft tissue sepsis secondary to tuberculosis.

In a 40-year-old Hispanic woman with pain and swelling in the left knee with a prosthesis, the combination of Ga-67 citrate and Tc-99m methylene diphosphonate (MDP) scans was used to indicate that there was a septic prosthetic joint. At surgery, the joint was infected and a foreign body was found. Cultures positive for tuberculosis were found also. The presence of an incongruent Ga-67 and Tc-99m (MDP) scan pattern suggests infection of the prosthetic joint, as in the following case.