Expanding the Utilization of Rectal Spacer Hydrogel for Larger Prostate Glands (>80 cc): Feasibility and Dosimetric Outcomes

Purpose

The Hydrogel Spacer Prospective Randomized Pivotal Trial achieved mean rectoprostatic spacing of 12.6 mm resulting in lowering of rectal V70 from 12.4% (without spacer) to 3.3% (with spacer) in patients with glands up to 80 cm³. The value of this approach in patients with larger glands is inadequately established. This study assesses the feasibility and dosimetric outcomes of perirectal spacing in patients with prostate cancer with larger glands (>80 cm³).

Methods and Materials

Between January 2017 and December 2019, 33 patients with prostate glands >80 cm³ (mean 108.1 cm³; range, 81.1-186.6 cm³) were treated, 15 with glands >80 to 100 cm³ and 18 >100 cm³. Median follow-up was 10 months (range, 3-26). The median international prostate symptom score was 9 (range, 1-18). Hydrogel was placed under local anesthesia in all cases. Treatment modality included intensity modulated radiation therapy in 15 and proton therapy (PT) in 18 patients. Treatment targeted the prostate plus seminal vesicles in 21 patients and 12 also had elective nodal irradiation. Conventional fractionation (CF) to 78 Gy in 39 fractions was used in 16 and moderate hypofractionation (HF) to 70 Gy in 28 fractions in 17 patients.

Results

In the CF group, mean rectum (r) V75, 70, 60, 50 was 0.87%, 2.25%, 5.61%, and 10.5%, respectively. For glands >80 to 100 cm³ and >100 cm³, rV70 was 2.55% and 2%, respectively. In HF patients, mean rV65, 63, 60, and 50 was 1.67%, 2.3%, 3.4%, and 8.6%. For glands >80 to 100 cm³ and >100 cm³, rV63 was 2% and 2.56%, respectively. Overall, the mean midgland rectoprostatic hydrogel separation was 9.3 mm (range, 4.7-19.4 mm). All patients tolerated treatment well; no acute grade 2 or higher adverse gastrointestinal events were observed.

Conclusions

Hydrogel placement is feasible in prostate glands larger than 80 cm³ with favorable dosimetric outcomes.

A low-affinity Ca2+-dependent association of calmodulin with the Rab3A effector domain inversely correlates with insulin exocytosis

The stimulus-response coupling pathway for glucose-regulated insulin secretion has implicated a rise in cytosolic [Ca2+]i as a key factor to induce insulin exocytosis. However, it is unclear how elevated [Ca2+]i communicates with the pancreatic beta-cell's exocytotic apparatus. As Rab3A is a model protein involved in regulated exocytosis, we have focused on its role in regulating insulin exocytosis. By using a photoactivatable cross-linking synthetic peptide that mimics the effector domain of Rab3A and microsequence analysis, we found calmodulin to be a major Rab3A target effector protein in pancreatic beta-cells. Coimmunoprecipitation analysis from pancreatic islets confirmed a Rab3A-calmodulin interaction in vivo, and that it inversely correlated with insulin exocytosis. Calmodulin affected neither GTPase nor guanine nucleotide exchange activity of Rab3A. The calmodulin-Rab3A interaction was pH- and Ca2+-dependent, and it was preferential for GTP-bound Rab3A. However, Rab3A affinity for calmodulin was relatively low (Kd = 18-22 micromol/l at 10(-5) mol/l [Ca2+]) and competed by other calmodulin-binding proteins that had higher affinity (e.g., Ca2+/calmodulin-dependent protein kinase-2 [CaMK-2] [Kd = 300-400 nmol/l at 10(-5) mol/l [Ca2+]]). Moreover, the Ca2+ dependence of the calmodulin-Rab3A interaction (K0.5 = 15-18 micromol/l [Ca2+], maximal at 100 micromol/l [Ca2+]) was significantly lower compared with that of the calmodulin-CaMK-2 association (K0.5 = 40 micromol/l [Ca2+], maximal at 1 mmol/l [Ca2+]). The data suggested that a transient Rab3A-calmodulin interaction might represent a means of directing calmodulin to the cytoplasmic face of a beta-granule, where it can be subsequently transferred for activation of other beta-granule-associated calmodulin-binding proteins as local [Ca2+]i rises to promote insulin exocytosis.

[Results of ESWL treatment in children with urolithiasis: own experience]

Actually extracorporeal shock wave lithotripsy (ESWL) is the most frequent method in the treatment of urolithiasis in children. The aim of the study was to estimate the results of ESWL in children with urolithiasis. Between 1991 and 1999 y, in our Department 260 "reno-ureteral units" in 203 children were treated by lithotripsy. Totally of 518 ESWL procedures were performed. In general efficacy of ESWL was 88.08%, in children with single stone in kidney--97.80%., with multiple stones in kidneys--78.65%, in ureterolithiasis--71.88%. For complete recovery in patients mean 1.99 ESWL procedures were performed on 1 "reno-ureteral unit" on the average diameter of the stone/stones 13.3 mm.

[A form of premorbid condition of urolithiasis and urinary stone composition in children with urolithiasis]

In diagnosis, monitoring and prophylaxis of urolithiasis it is important to use simple, non-invasive tests. The aim of the study was to define the value of crystallizing ratios in urine in correlation with chemical stone composition in presumptive diagnosis and monitoring patients with urolithiasis. The study involved 102 children. An analysis of chemical stone composition was carried out in 62 cases. A correlation between values of crystallizing ratios in the urine, indicating the kind of preurolithiasis state and chemical stone composition has been found.

[Etiology of nephrolithiasis in children: own observation]

Recurrent formation of renal calculi may be prevented by selective medical therapy designed to correct underlying metabolic disturbances in urine biochemistry. The aim of the study was to estimate potential risk factors of urolithiasis in 102 children before ESWL treatment. Metabolic disturbances followed by anatomical malformations of urinary tract, recurrent urinary tract infections caused by urease-induced microorganisms are the most frequent risk factors. In single cases possible risk factors were: immobilization and chronic corticosteroid therapy.

[Beta-2 microglobulinuria in children with vesico-ureteral reflux and recurrent urinary tract infections]

Recurrent urinary tract infections in children with vesico-ureteral reflux are the one of risk factors in the process of reflux nephropathy. One of markers of early kidney parenchyma damage is beta 2-microglobulin. The aim of the study was to evaluate the value of beta 2-microglobulin excretion in urine and its serum levels in children with vesico-ureteral reflux and recurrent urinary tract infections. It was found that abnormal urinary excretion of beta 2-microglobulin and its serum levels of proceeded post-inflammatory changes in kidney parenchyma observed in imaging examinations of urinary tract and impared parameters of renal function in biochemical analyses.

Morphological brain damage, functional disorders and the possibilities of their treatment in children with infantile cerebral palsy

Twenty-four children with infantile cerebral palsy (6 girls and 18 boys aged 3-17 years), surgically treated in the years 1993-1997, were involved in the study. Neurological-orthopaedic examinations and computer tomography (CT) of the head allowed precise diagnosis and understanding of its pathology. The group consisted of 10 patients with hemiplegia, 10 with diplegia and 4 with severe quadriplegia. In 18 children changes in the brain were largely dependent on the clinical type of paresis. In hemiparesis, unilateral changes, such as cerebral cortex atrophy with enlarged ventricles, were predominant. Diplegia cases frequently showed periventricular damage to the white matter. Brain tomography in severe quadriplegia did not always correspond to the clinical condition. CT examinations revealed no abnormalities in the brain in 6 out of 24 cases. Since the results of rehabilitation were not satisfactory, 29 surgical procedures were performed in the presented group of patients, with improved the course of therapeutic rehabilitation or nursing care in all the children.

Rab3A effector domain peptides induce insulin exocytosis via a specific interaction with a cytosolic protein doublet

A key protein involved in the regulated exocytotic mechanism in neuroendocrine cells is the GTP-binding protein, Rab3A. Rab3A is thought to mediate exocytosis by an interaction of its effector domain with a putative effector protein. We demonstrate here that Rab3A effector domain peptides specifically stimulated insulin exocytosis in electroporated insulin-secreting cells (K0.5 activation, 6-8 microM) in a Ca(2+)-independent manner, although in the presence of Ca2+ insulin exocytosis was further potentiated. By using a 125I-radiolabeled photoactivated cross-linking Rab3A effector domain peptide, we identified a cytosolic protein doublet (REEP-1 and REEP-2), which specifically interacted with the Rab3A effector domain. Competitive inhibition studies revealed this protein-protein interaction to be at a concentration equivalent to that required for Rab3A effector domain peptides to trigger insulin exocytosis (Ki, 6-8 microM). Furthermore, under basal secretory conditions REEP-1 and -2 were membrane-associated, but upon stimulation of exocytosis they were released into a cytosolic fraction. Our results suggest that REEP-1 and -2 are part of the regulated exocytotic machinery, and their dissociation upon stimulation of hormone release (likely from a protein complex) may be essential to the mechanism that triggers regulated exocytosis in pancreatic beta-cells.

The glucose tolerance, insulin response and pancreatic exocrine function in patients after acute pancreatitis

In 25 patients having a history of acute pancreatitis (AP) in anamnesis one year ago and in 12 control subjects the insulin response to oral glucose was investigated and in some cases the exocrine function of pancreas was evaluated. The disturbances in glucose tolerance occurred in about 30% of the patients and were associated with impairment of insulin response and deterioration of exocrine pancreatic function. The double cortisone and glucose load did not influence the glucose tolerance in the patients. In persons investigated during AP and one year later only slight improvement of insulin response was noted. The results support the significance of follow-up studies of carbohydrate tolerance and insulin response in patients after AP for the evaluation of the diabetic risk in such cases.