Dosimetric effect of set-up error in accelerator-based boron neutron capture therapy for head and neck cancer

The dosimetric effect of set-up error in boron neutron capture therapy (BNCT) for head and neck cancer remains unclear. In this study, we analyzed the tendency of dose error by treatment location when simulating the set-up error of patients. We also determined the tolerance level of the set-up error in BNCT for head and neck cancer. As a method, the distal direction was shifted with an interval of 2.5 mm, from 0.0 mm to +20.0 mm and compared with the dose at the reference position. Similarly, the horizontal direction and vertical direction were shifted, with an interval of 5.0 mm, from −20.0 mm to +20.0 mm. In addition, cases with 3.0 mm and 5.0 mm simultaneous shifts in all directions were analyzed as the worst-case scenario. The dose metrics of the minimum dose of the tumor and the maximum dose of the mucosa were evaluated. From unidirectional set-up error analysis, in most cases, the set-up errors with dose errors within ±5% were Δdistal < +2.5 mm, Δhorizontal < ±5.0 mm and Δvertical < ±5.0 mm. In the simulation of 3.0 mm shifts in all directions, the errors in the minimum tumor dose and maximum mucosal dose were −3.6% ±1.4% (range, −5.4% to −0.6%) and 2% ±1.4% (range, 0.4% to 4.5%), respectively. From these results, if the set-up error was within ±3.0 mm in each direction, the dose errors of the tumor and mucosa could be suppressed within approximately ±5%, which is suggested as a tolerance level.     

Determining a methodology of dosimetric quality assurance for commercially available accelerator-based boron neutron capture therapy system

The irradiation field of boron neutron capture therapy (BNCT) consists of multiple dose components including thermal, epithermal and fast neutron, and gamma. The objective of this work was to establish a methodology of dosimetric quality assurance (QA), using the most standard and reliable measurement methods, and to determine tolerance level for each QA measurement for a commercially available accelerator-based BNCT system. In order to establish a system of dosimetric QA suitable for BNCT, the following steps were taken. First, standard measurement points based on tissue-administered doses in BNCT for brain tumors were defined, and clinical tolerances of dosimetric QA measurements were derived from the contribution to total tissue relative biological effectiveness factor-weighted dose for each dose component. Next, a QA program was proposed based on TG-142 and TG-198, and confirmed that it could be assessed whether constancy of each dose component was assured within the limits of tolerances or not by measurements of the proposed QA program. Finally, the validity of the BNCT QA program as an evaluation system was confirmed in a demonstration experiment for long-term measurement over 1 year. These results offer an easy, reliable QA method that is clinically applicable with dosimetric validity for the mixed irradiation field of accelerator-based BNCT.     

Prevention of surgical adhesions with gelatine sealing sheet in a canine adhesion model

Open in a separate window OBJECTIVESAlthough reoperation has been increasingly performed in cardiovascular surgery in recent years, preventing surgical adhesions remains an unsolved complication. Therefore, this study aimed to investigate whether gelatine sealing sheets are more effective than fibrin sealing sheets in preventing surgical adhesions.METHODSBilateral femoral arteries of 20 beagle dogs under general anaesthesia were pricked with syringe needles, and gelatine and fibrin sealing sheets were applied on the bleeding points to make canine adhesion models. The femoral artery was harvested after 4 and 12 weeks to evaluate adhesion formations. The adhesive grade was quantified by scoring the area and strength of adhesion tissues. Histological staining was performed to examine the structural features of surgical adhesions.RESULTSSignificantly fewer macroscopic adhesions were observed with gelatine sealing sheets than those with fibrin sealing sheets at 4 and 12 weeks postoperatively. Microscopically, CD3+ T lymphocytes at 4 and 12 weeks postoperatively in gelatine sealing sheets were significantly lower than those in fibrin sealing sheets. Microvessel density determined by CD34 at 4 and 12 weeks postoperatively in gelatine sealing sheets was also significantly lower than those in fibrin sealing sheets.CONCLUSIONSThe gelatine sealing sheets are more effective than the fibrin sealing sheets in preventing surgical adhesions. These findings suggest that the gelatine sealing sheet may help prevent adhesions and thus be a therapeutically effective biomaterial in vascular surgery.     

Genetically Diverse Highly Pathogenic Avian Influenza A(H5N1/H5N8) Viruses among Wild Waterfowl and Domestic Poultry,Japan, 2021

Genetic analyses of highly pathogenic avian influenza H5 subtype viruses isolated from the Izumi Plain, Japan, revealed cocirculation of 2 genetic groups of clade 2.3.4.4b viruses among migratory waterfowl. Our findings demonstrate that both continuous surveillance and timely information sharing of avian influenza viruses are valuable for rapid risk assessment.     

Transplantation of bone marrow stromal cell-derived Schwann cells promotes axonal regeneration and functional recovery after complete transection of adult rat spinal cord

The aim of this study was to evaluate whether transplantation of Schwann cells derived from bone marrow stromal cells (BMSC-SCs) promotes axonal regeneration and functional recovery in completely transected spinal cord in adult rats. Bone marrow stromal cells (BMSCs) were induced to differentiate into Schwann cells in vitro. A 4-mm segment of rat spinal cord was removed completely at the T7 level. An ultra-filtration membrane tube, filled with a mixture of Matrigel (MG) and BMSC-SCs (BMSC-SC group) or Matrigel alone (MG group), was grafted into the gap. In the BMSC-SC group, the number of neurofilament- and tyrosine hydroxylase-immunoreactive nerve fibers was significantly higher compared to the MG group, although 5-hydroxytryptamine- or calcitonin gene-related peptide-immunoreactive fibers were rarely detectable in both groups. In the BMSC-SC group, significant recovery of the hindlimb function was recognized, which was abolished by retransection of the graft 6 weeks after transplantation. These results demonstrate that transplantation of BMSC-SCs promotes axonal regeneration of lesioned spinal cord, resulting in recovery of hindlimb function in rats. Transplantation of BMSC-SCs is a potentially useful treatment for spinal cord injury.     

Expression of parathyroid hormone/parathyroid hormone-related peptide receptor 1 in normal and diseased bladder detrusor muscles: a clinico-pathological study

Background

To investigate the expression of parathyroid hormone (PTH)/PTH-related peptide (PTHrP) receptor 1 (PTH1R) in clinical specimens of normal and diseased bladders. PTHrP is a unique stretch-induced endogenous detrusor relaxant that functions via PTH1R. We hypothesized that suppression of this axis could be involved in the pathogenesis of bladder disease.

Methods

PTH1R expression in clinical samples was examined by immunohistochemistry. Normal kidney tissue from a patient with renal cancer and bladder specimens from patients undergoing ureteral reimplantation for vesicoureteral reflux or partial cystectomy for urachal cyst were examined as normal control organs. These were compared with 13 diseased bladder specimens from patients undergoing bladder augmentation. The augmentation patients ranged from 8 to 31 years old (median 15 years), including 9 males and 4 females. Seven patients had spinal disorders, 3 had posterior urethral valves and 3 non-neurogenic neurogenic bladders (Hinman syndrome).

Results

Renal tubules, detrusor muscle and blood vessels in normal control bladders stained positive for PTH1R. According to preoperative urodynamic studies of augmentation patients, the median percent bladder capacity compared with the age-standard was 43.6% (range 1.5–86.6%), median intravesical pressure at maximal capacity was 30 cmH₂O (range 10–107 cmH₂O), and median compliance was 3.93 ml/cmH₂O (range 0.05–30.3 ml/cmH₂O). Detrusor overactivity was observed in five cases (38.5%). All augmented bladders showed negative stainings in PTH1R expression in the detrusor tissue, but positive staining of blood vessels in majority of the cases.

Conclusions

Downregulation of PTH1R may be involved in the pathogenesis of human end-stage bladder disease requiring augmentation.     

Living With Stillborn Babies as Family Members: Japanese Women Who Experienced Intrauterine Fetal Death After 28 Weeks Gestation

My purpose in this qualitative research was to describe the meaning of fetal death in the lives of Japanese women in a local community by interviewing women who experienced intrauterine fetal death (IUFD) after 28 weeks of gestation in chronological order from the time they were told of the fetal death to the present day. The study included 17 women who had experienced fetal death and who raised the dead child through “the development process of becoming a parent” and “the grieving process after the loss of a child,” comprising a year-long grieving process.     

Experience of coronary artery bypass grafting on the beating heart with right heart bypass; 3 cases of octogenarian

Right heart bypass (RHB) yields more stable hemodynamics by increasing left ventricular preload and collapse right ventricular chamber during the displacement of the heart on beating heart coronary artery bypass grafting (CABG). Recently beating heart CABG gaining popularity, and the indications for CABG have increasingly expanded to elderly person. Using RHB while exposing posterior branches by displacing the beating heart, we have attempted to make total revascularization in beating heart CABG. We performed beating heart CABG with RHB in 3 cases of octogenarian. All patients had left main trunk lesion and needed revascularization of posterior vessels. Introduction of RHB enabled us to approach to posterior target vessels in better exposure and under greater hemodynamic stability. All three patients had no complications postoperatively. Strictly speaking CABG with RHB is not off-pump CABG, but RHB system does not include either artificial lung or manipulation of the aorta. Therefore we think it is very effective support system which enables multiple coronary revascularization for elderly person.     

Mucinous cystic tumors of the pancreas

Purpose: This study was conducted to clarify the clinicopathologic characteristics relevant to the specific diagnosis of mucinous cystic tumors of the pancreas. Methods: We retrospectively reviewed the clinical features and histopathologic findings of five patients who underwent curative resection for mucinous cystic tumors of the pancreas at our hospital between 1975 and 2000. Results: All five patients were women, ranging in age from 36 to 69 years, and the tumors were located in the pancreatic body and tail. Histopathologically, three tumors were mucinous cystadenomas and two were mucinous cystadenocarcinomas. All five tumors had ovarian-type stroma, and stromal luteinization was found in the three adenomas. These tumors were classified into two groups according to whether the epithelial lining was endocervical or intestinal. All tumors were spherical and multilocular with a fibrous pseudocapsule. On T1-weighted magnetic resonance images, mucinous cystadenomas with watery mucin showed low signal intensity, but mucinous cystadenocarcinomas with gelatinous mucin or hemorrhagic contents demonstrated high signal intensity. Conclusions: Signal intensity on T1-weighted magnetic resonance images provides highly useful diagnostic information on mucinous cystic tumors of the pancreas. Furthermore, tumors may be classified into two groups according to the type of epithelial lining. Received: December 19, 2001 / Accepted: May 7, 2002 Reprint requests to: T. Hara