Development of disease-specific growth charts for Korean children with Beckwith-Wiedemann syndrome

Beckwith-Wiedemann syndrome (BWS) is an epigenetic overgrowth syndrome. Despite its distinctive growth pattern, the detailed growth trajectories of children with BWS remain largely unknown. We retrospectively analyzed 413 anthropometric measurements over an average of 4.4 years of follow-up in 51 children with BWS. We constructed sex-specific percentile curves for height, weight, and head circumference using a generalized additive model for location, scale, and shape. Males with BWS exhibited greater height at all ages evaluated, weight before the age of 10, and head circumference before the age of 9 than those of the general population. Females with BWS showed greater height before the age of 7, weight before the age of 4.5, and head circumference before the age of 7 than those of the general population. At the latest follow-up visit at a mean 8.4 years of age, bone age was significantly higher than chronological age. Compared to paternal uniparental disomy (pUPD), males with imprinting center region 2-loss of methylation (IC2-LOM) had higher standard deviation score (SDS) for height and weight, while females with IC2-LOM showed larger SDS for head circumference. These disease-specific growth charts can serve as valuable tools for clinical monitoring of children with BWS.

Efficacy and safety of long-term repeated use of rituximab in pediatric patients with nephrotic syndrome

BACKGROUND

We aimed to investigate the efficacy and safety of repeated use of rituximab (RTX) in pediatric patients with nephrotic syndrome (NS).

METHODS

Retrospective review of 50 patients with steroid-dependent NS (SDNS) who had received more than three cycles of RTX was conducted; each consisted of one to four infusions until B lymphocytes were depleted.

RESULTS

The median age of starting the first RTX cycle was 12.4 years (interquartile ranges (IQR) 10.2-14.6). During a median follow-up period of 6.3 (IQR 3.6-8.6) years, patients received a median of 5.0 RTX cycles (IQR 4.0-7.3). The number of relapses decreased from a median of 2.0 relapses per year (IQR 1.0-3.0) to 0.2 relapses per year (IQR 0.0-0.5) after long-term RTX treatments (P < 0.001). Longer relapse-free periods were associated with more than four RTX cycles, longer B-cell depletion, older age at each RTX treatment, and lower cholesterol levels. B lymphocytes recovered to 1% at a median of 5.9 months (95% confidence interval 5.7-6.1) after RTX administration. Factors related to a longer period of B-cell depletion included more than five RTX cycles, a higher dose of RTX, older age at treatment, and concurrent use of antimetabolites. During repeated RTX treatments, 8.0%, 6.0%, and 2.0% of patients developed hypogammaglobulinemia, severe infection, and severe neutropenia, respectively.

CONCLUSIONS

Long-term repeated use of RTX may be effective and safe in pediatric NS patients. Furthermore, the redosing of RTX could be chosen by considering predictive factors for relapse-free and B-cell depletion periods.

Effect of donor-recipient size mismatch on long-term graft survival in pediatric kidney transplantation: a multicenter cohort study

BACKGROUND

Donor-recipient size mismatching is commonly occurs in pediatric kidney transplantation (KT). However, its effect on graft survival remains unknown. This study aimed to determine the effect of donor-recipient size mismatch on the long-term survival rate of transplant kidneys in pediatric KT.

METHODS

A total of 241 pediatric patients who received KT were enrolled. The medical records of all patients were retrospectively reviewed, and the correlation between donor-recipient size mismatch and graft function and long-term graft outcome was analyzed according to donor-recipient size mismatch.

RESULTS

Recipients and donors' mean body weight at the time of KT were 34.31 ± 16.85 and 56.53 ± 16.73 kg, respectively. The mean follow-up duration was 96.49 ± 52.98 months. A significant positive correlation was observed between donor-recipient body weight ratio (DRBWR) or donor-recipient body surface area ratio (DRBSR) and graft function until 1 year after KT. However, this correlation could not be confirmed at the last follow-up. The results of long-term survival analysis using Fine and Gray's subdistribution hazard model showed no significant difference of the survival rate of the transplant kidney according to DRBWR or DRBSR.

CONCLUSION

Donor-recipient size mismatch in pediatric KT is not an important factor in determining the long-term prognosis of transplant kidneys.

Corrigendum: Long-term outcome of Bartter syndrome in 54 patients: a multicenter study in Korea

[This corrects the article DOI: 10.3389/fmed.2023.1099840.].

Long-term outcome of Bartter syndrome in 54 patients: A multicenter study in Korea

Introduction

Bartter syndrome (BS) is a rare salt-wasting tubulopathy caused by mutations in genes encoding sodium, potassium, or chloride transporters of the thick ascending limb of the loop of Henle and/or the distal convoluted tubule of the kidney. BS is characterized by polyuria, failure to thrive, hypokalemia, metabolic alkalosis, hyperreninemia, and hyperaldosteronism. Potassium and/or sodium supplements, potassium-sparing diuretics, and nonsteroidal anti-inflammatory drugs can be used to treat BS. While its symptoms and initial management are relatively well known, long-term outcomes and treatments are scarce.

Methods

We retrospectively reviewed 54 Korean patients who were clinically or genetically diagnosed with BS from seven centers in Korea.

Results

All patients included in this study were clinically or genetically diagnosed with BS at a median age of 5 (range, 0–271) months, and their median follow-up was 8 (range, 0.5–27) years. Genetic diagnosis of BS was confirmed in 39 patients: 4 had SLC12A1 gene mutations, 1 had KCNJ1 gene mutations, 33 had CLCNKB gene mutations, and 1 had BSND mutation. Potassium chloride supplements and potassium-sparing diuretics were administered in 94% and 68% of patients, respectively. The mean dosage of potassium chloride supplements was 5.0 and 2.1 mEq/day/kg for patients younger and older than 18 years, respectively. Nephrocalcinosis was a common finding of BS, and it also improved with age in some patients. At the last follow-up of 8 years after the initial diagnosis, 41% had short stature (height less than 3rd percentile) and impaired kidney function was observed in six patients [chronic kidney disease (CKD) G3, n = 4; CKD G5, n = 2].

Conclusion

BS patients require a large amount of potassium supplementation along with potassium-sparing agents throughout their lives, but tend to improve with age. Despite management, a significant portion of this population exhibited growth impairment, while 11% developed CKD G3–G5.

Bartter Syndrome: Perspectives of a Pediatric Nephrologist

Bartter syndrome (BS) is one of the most well-known hereditary tubular disorders, characterized by hypokalemic, hypochloremic metabolic alkalosis, and polyuria/polydipsia. This disease usually presents before or during infancy, and adult nephrologists often inherit the patients from pediatric nephrologists since this is a life-long condition. Here, a few case scenarios will be presented to recount how they first got diagnosed and how their clinical courses were during childhood until adulthood, in addition to a brief review of the disease and its treatment.

Case report: Genetic defects in laminin α5 cause infantile steroid-resistant nephrotic syndrome

Single gene pathogenic mutations have been implicated in up to 30% of pediatric steroid-resistant nephrotic syndrome (SRNS) cases, mostly in infantile patients. Among them is LAMA5, which has been recently discovered and encodes the laminin α5 chain. The laminin α5β2γ1 heterotrimer is an essential component of the glomerular basement membrane and is necessary for embryogenesis and immune modulation. Biallelic LAMA5 variants have been identified in one adult and ten pediatric nephrotic syndromes (NS) patients with variable phenotypes. Biallelic truncating mutations in this gene have recently been proven to cause SRNS. Here, we present another case of infantile SRNS related to novel compound heterozygous variations of LAMA5 (c.3434G > A, p.Cys1145Tyr and c.6883C > T, p.Gln2295*), the first reported case with one missense and one nonsense allele. A 10-month-old female patient presented with eyelid edema and massive proteinuria without any extrarenal symptoms or family history. The patient was diagnosed with SRNS. Renal biopsy revealed focal segmental glomerulosclerosis with widely effaced epithelial foot processes and a "moth-eaten" appearance. She progressed to end stage kidney disease (ESKD), requiring dialysis at 31 months of age, and underwent a deceased-donor kidney transplant at 6 years of age. Four months after transplantation, she developed Ebstein-Barr Virus (EBV) infection related to post-transplantation lymphoproliferative disorder (PTLD). After chemotherapy, the patient remained healthy with adequate renal function without disease recurrence for the past 7 years. We also identified previous cases of biallelic LAMA5 variants associated with the nephrotic phenotype and analyzed the available clinical and genetic information. All reported patients had an onset of NS ranging from 3 months to 8 years, with no other syndromic features. Response to therapy and renal outcomes varied greatly; most patients exhibited steroid resistance, five progressed to ESKD, and two received kidney transplantation (KT). There was one report of PTLD. Our patient's phenotype was markedly more severe than those with biallelic missense variants and somewhat less severe than those with two truncating variants. LAMA5 defects may also play a role in PTLD, though no conclusions can be made with such limited cases. LAMA5 should be considered a candidate gene for SRNS and should be actively tested in cases with no other genetic diagnosis.

Optimal application of compressive palatal stents following mesiodens removal in pediatric patients: A Randomized Controlled Trial

Background

There is no scientific evidence supporting the choice of a palatal stent in patients who underwent removal of an impacted supernumerary tooth. We aimed to investigate the effects of palatal stents in patients who underwent supernumerary tooth removal through a palatal approach and to suggest the optimal stent thickness and material.

Material and Methods

We recruited 144 patients who underwent extraction of a supernumerary tooth between the maxillary anterior teeth. Subjects were assigned to a control group (CG) or one of four compressive palatal stent groups (CPSGs) classified by the thickness and material of the thermoplastic acrylic stent used. Palatal gingival swelling and objective indices (healing, oral hygiene, gingival, and plaque) were evaluated before surgery and on postoperative days (PODs) 3, 7, and 14; pain/discomfort and the Child Oral Health Impact Profile (COHIP) were assessed as subjective indices of the effects of the stent.

Results

The CPSGs showed faster healing than did the CG on PODs 7 (P<0.001) and 14 (P=0.043); swelling was measured by 1.64±0.88 mm and 4.52±0.39 mm, respectively. Although swelling was least in the 4-mm hard group (0.92±0.33 mm), the difference compared with that in the 2-mm hard group (1.01±0.18 mm) was not significant (P=0.077). The CPSGs showed better COHIP (P<0.001-0.036) and pain scores (P<0.001) than did the CG on PODs 1-3.

Conclusions

Compressive palatal stents reduce discomfort by decreasing pain and alleviating swelling. Although a stent is effective regardless of its thickness and material, 2-mm hard stents maximized such positive effects with minimal discomfort.

Key words:Supernumerary tooth, tooth Extraction, postoperative care, oral Health, pediatric dentistry.

Genetic and clinical heterogeneity in Korean patients with Rubinstein-Taybi syndrome

Background

Rubinstein–Taybi syndrome (RSTS) is a rare congenital malformation syndrome with clinical characteristics such as hypertrichosis, high arched eyebrows, large beaked nose, and broad thumbs and halluces. RSTS patients showed intellectual disability and health problems such as short stature, ophthalmologic abnormalities, congenital heart defects, genitourinary defects, and variable types of tumors. Although mutations in CREBBP and EP300 genes are associated with RSTS features, genetic causation is still unknown in 30% of patients.

Methods

We present clinical and molecular genetic characteristics of 25 unrelated Korean patients clinically diagnosed with RSTS. Sanger sequencing analysis and multiplex ligation‐dependent probe amplification for CREBBP in 25 patients and exome sequencing of CREBBP‐negative cases were performed in nine patients successively.

Results

Causative variants were identified in 20 (80%) patients: 16 (64%) in CREBBP and 4 (16%) in EP300. All the identified variants predict protein truncation (11 frameshift, 2 nonsense, 1 splicing‐site, and 6 large intragenic deletions); there are no repeatedly identified sequence variants. Four of the CREBBP and all four EP300 variants are novel. Intellectual disability was noted in 24/25 patients (96%); no difference was found between CREBBP and EP300 groups. One patient with a CREBBP variant (4%) had malignant tumor.

Conclusions

To date, this is the largest cohort of patients with RSTS including EP300‐related patients in Korea. Future large‐scale studies to find genetic mutation of molecularly unsolved patients and long‐term prospective studies are required to validate our results.

Phenotypic and Genetic Characteristics of Five Korean Patients with Costello Syndrome

Costello syndrome (CS) is a rare genetic disorder characterized by distinctive facial appearance, cardiopulmonary complications, severe growth retardation, skin and skeletal defects, developmental delay, and tumor predisposition. CS is caused by heterozygous de novo mutations in the proto-oncogene HRAS, which is a component of the RAS/mitogen-activated protein kinase pathway. Herein, we reviewed the phenotypic and genetic features of 5 Korean patients who were genetically diagnosed with CS. Atrial tachycardia and polyhydramnios, which are important prenatal features for CS, were observed in 4 and 5 patients, respectively. The distinctive coarse facial appearances of the patients and presence of deep palmoplantar creases supported the clinical diagnosis of CS, which was confirmed by HRAS sequence analysis. Extremely poor postnatal growth was observed in all 5 patients. Further, all patients exhibited cardiac abnormalities; left ventricular hypertrophy and hypertrophic cardiomyopathy were observed in 3 patients. All 5 patients suffered from airway problems; 3 of them required intubation right after birth, and 2 of them received tracheostomy. One patient with a p.Gly12Ser mutation was diagnosed with retroperitoneal rhabdomyosarcoma alveolar type at the age of 5 years. Consistent with previous reports, both patients with p.Gly12Cys mutations died within the first year of life due to cardiopulmonary failure. Our study summarizes the characteristics of these 5 Korean patients with CS and, along with previous studies, provides clues for genotype-phenotype correlation in patients with CS.

Hypoxia improves hair inductivity of dermal papilla cells via nuclear NADPH oxidase 4-mediated reactive oxygen species generation'

BACKGROUND

Dermal papilla cells (DPCs) play a key role in hair regeneration and morphogenesis. Therefore, tremendous efforts have been made to promote DPC hair inductivity.

OBJECTIVES

The aim of this study was to investigate the mitogenic and hair inductive effects of hypoxia on DPCs and examine the underlying mechanism of hypoxia-induced stimulation of DPCs.

METHODS

DPCs' hair inductivity was examined under normoxia (20% O₂ ) and hypoxia (2% O₂ ).

RESULTS

Hypoxia significantly increased the proliferation and delayed senescence of DPCs via Akt phosphorylation and downstream pathways. Hypoxia upregulated growth factor secretion of DPCs through the mitogen-activated protein kinase pathway. Hypoxia-preconditioned DPCs induced the telogen-to-anagen transition in C₃ H mice, and also enhanced hair neogenesis in a hair reconstitution assay. Injected green fluorescent protein-labelled DPCs migrated to the outer root sheath of the hair follicle, and hypoxia-preconditioning increased survival and migration of DPCs in vivo. Conditioned medium obtained from hypoxia increased the hair length of mouse vibrissa follicles via upregulation of alkaline phosphatase, vascular endothelial growth factor, and glial cell line-derived neurotrophic factor. We examined the mechanism of this hypoxia-induced stimulation, and found that reactive oxygen species (ROS) play a key role. For example, inhibition of ROS generation by N-acetylcysteine or diphenyleneiodonium treatment attenuated DPCs' hypoxia-induced stimulation, but treatment with ROS donors induced mitogenic effects and anagen transition. NADPH oxidase 4 is highly expressed in the DPC nuclear region, and NOX4 knockout by CRISPR-Cas9 attenuated the hypoxia-induced stimulation of DPCs.

CONCLUSIONS

Our results suggest that DPC culture under hypoxia has great advantages over normoxia, and is a novel solution for producing DPCs for cell therapy. What's already known about this topic? Dermal papilla cells (DPCs) play a key role in hair regeneration and morphogenesis, but they are difficult to isolate and expand for use in cell therapy. Tremendous efforts have been made to increase proliferation of DPCs and promote their hair formation ability. What does this study add? Hypoxia (2% O₂ ) culture of DPCs increases proliferation, delays senescence and enhances hair inductivity of DPCs. Reactive oxygen species play a key role in hypoxia-induced stimulation of DPC. What is the translational message? Preconditioning DPCs under hypoxia improves their hair regenerative potential, and is a novel solution for producing DPCs for cell therapy to treat hair loss.

Creating virtual 3-dimensional models for teaching pre-clinical tooth preparation: Students' usages and perceptions

PURPOSE

This research aimed to evaluate the students' usage and perceptions of using smartphones in their general dental education and learning tooth preparation with the individually designed virtual 3D instructional models in the pre-clinical removable partial denture course.

MATERIALS AND METHODS

Second-year dental students were asked to voluntarily participate in a survey to investigate their demographic information, general usages of smartphones, perception of smartphones usage in dental education (construct 1) and perception of individually designed virtual 3D instructional models (construct 2). Students' responses of general usages of the smartphones were compared with their demographic and educational backgrounds using nonparametric Kruskal-Wallis test (for age) and Fisher's exact test (for sex, race and educational background). The sums of scores of the construct 1 and construct 2 were tested for associations with student's demographic and educational backgrounds using the Pearson product-moment correlation (for age), t test (for sex and educational background) or one-way ANOVA F test (for race) (α = .05).

RESULTS

A 75% response rate (N = 90) was achieved in this study, and all 90 participants owned smartphones. Students' responses to general usages of the smartphones were not significantly influenced by their demographic background. For the construct 1, more than 73% of participants responded either agree or strongly agree to the usage of smartphones in general dental education and pre-clinical setting; however, only 49% of participants responded the same way in the clinical setting. For the construct 2, 48 of 90 participants viewed the 3D models, and more than 73% of these 48 participants responded either agree or strongly agree to the usage of the 3D models in the pre-clinical course. Student's demographic background did not have significant influence on the sums of scores of the construct 1 and construct 2.

CONCLUSIONS

Within the limitations of this study, high usages and ownerships of smartphones were found amongst the students surveyed. The individually designed virtual 3D instructional models as supplemental teaching materials in the pre-clinical course were perceived positively by the students.

Abstract LB-308: Combination of CTx-0294945 a highly selective inhibitor of focal adhesion kinase with bevacizumab in pre-clinical models of breast cancer

Background: Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase that provides a critical hub for signalling from at least four different classes of cellular sensing mechanisms including growth factor receptors, GPCRs, integrins and mechanical stress forces. By temporal and spatial integration of signals from these sources, FAK plays a central role in cell migration, invasion and proliferation; processes vital for tumorigenesis. The significance of FAK to the function of signal transduction pathways provides a strong rationale for the combination of FAK inhibitors with other targeted agents to achieve improved efficacy against a range of cancers. Others have demonstrated the importance of FAK in angiogenesis and therefore combining a FAKi with anti-VEGF agents is attractive as it employs two complementary mechanisms of suppressing the formation of tumor vasculature. Here we present results from the co-administration of CTx-0294945, a highly selective FAKi, and bevacizumab (bev) in an orthotopic model of human breast cancer. Methods and Results: CTx-0294945 is an orally bioavailable small molecule ATP competitive inhibitor of focal adhesion kinase (FAK KD=0.21 nM). It exhibits high selectivity against a diverse panel of 125 kinases including the closely related Pyk2. CTx-0294945 inhibits autophosphorylation of 397Y-FAK in MDA-MB-231 cells with an IC50 = 7 nM and exhibits low general cellular toxicity (IC50 = 2.7 µM, MDA-MB-231 cells). CTx-0294945 is suitable for oral administration (%F=58 and t1/2=5.1 h at 20 mg/Kg in rat) and does not inhibit (IC50 &gt;20 µM) any of the cytochrome p450 isoforms tested to date. To assess the co-administration of CTx-0294945 with bev, mice were injected orthotopically with MDA-MB-231 cells (106). After 14 days, when tumors were palpable, mice were randomized into 4 groups and dosing commenced. The groups were treated with CTx-0294945 (80 mg/kg QD, PO), bev (12.5 mg/Kg IP, x2/week), CTx-0294945 (80 mg/Kg QD, PO) and bev (12.5 mg/Kg IP, x2/week) or vehicle. Tumor growth was monitored and on day 28 animals in the vehicle and CTx-0294945 arms were culled when the size of the tumors reached ethical end point (1000 mm3). Tumor growth in the bev only and the CTx-0294945 + bev arms was significantly inhibited (75% and 88% TGI respectively). At this time the treatment regimes for both cohorts were stopped and tumor growth allowed to progress. After an additional 14 days the experiment was terminated when the bev treatment group reached ethical end point; however the average size of the tumors in the CTx-0294945 + bev cohort was still was only 562 mm3. Conclusions: Our data suggest the potential utility of combining a selective FAK inhibitor with bevacizumab to prevent tumour progression and enhance the durability of response.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-308. doi:1538-7445.AM2012-LB-308

Phase II cisplatin, irinotecan, cetuximab and concurrent radiation therapy followed by surgery for locally advanced esophageal cancer

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Background: Weekly irinotecan, cisplatin, and concurrent radiation therapy is a well-tolerated, active regimen in locally advanced esophageal cancer. (Ilson. JCO 2003) Cetuximab, an EGFR inhibitor, is a potent radiation sensitizer in head and neck cancer. (Bonner. Proc ASCO 2004) Methods: In this phase II trial, patients (pts) with T2–4N0–1M0–1A esophageal adenocarcinoma (A) or squamous cell carcinoma (S) receive 5040 cGy/28 fractions of radiation therapy (RT) and concurrent weekly cisplatin 30mg/m2 plus irinotecan 65 mg/m2 on weeks 1, 2, 4, and 5, followed by surgery 4–8 weeks after completion of RT. Additionally, pts receive weekly infusions of cetuximab 250 mg during RT, up to one week before surgery, and for 6 months following surgery. Results: Seventeen pts have been entered: male: female = 14:3, median age 54, ECOG PS 0:1 = 6:11, A:S = 17:0, stage IIA:IIB:III:IVA = 6:1:8:2, tumor location-esophagus-mid:lower:gastroesophageal junction = 1:4:12, >10% weight loss-yes:no = 8:9. Of 17 pts entered, 15 pts have proceeded to surgery, 1 pt died from Aspergillus infection resulting in respiratory failure and sepsis, and 1 pt is pending surgery. Of the 15 pts who underwent surgery, 2 (13%) had a complete pathologic response; pathologic stage for other pts: 0 = 1, I = 3, IIA = 3, IIB = 1, III = 4, IV = 1. Grade III/IV toxicity (17 pts) was: diarrhea 9 pts, neutropenia 9 pts, febrile neutropenia 5 pts, anorexia 5 pts, vomiting 4 pts, fatigue 3 pts, mucositis 1 pt. Chemotherapy dose attenuation was required for diarrhea in 5 pts, for neutropenia in 4 pts, and for folliculitis in 1 pt. One patient was removed from study during week 6 for prolonged diarrhea/ dehydration. Due to the 2-step design of the trial, accrual is on hold pending a 3rd required pathologic CR in the first 17 patients. Conclusions: Compared to other trials of irinotecan, cisplatin, radiation therapy, and surgery in similar groups of esophageal cancer patients, early results for this combination with cetuximab suggest a lower complete response rate and higher overall toxicity. Additional data will be available at ASCO. Supported by Bristol-Myers Squibb.

No significant financial relationships to disclose.

Studies of site selective hydrogen atom abstractions by Cl atoms from isobutane and propane by laser flash photolysis/IR diode laser spectroscopy

The kinetics of chlorine atom abstractions from normal and selectively deuterated propane and isobutane have been measured at room temperature and 195 K using a laser flash photolysis system, and following the course of the reaction via IR diode laser absorption measurements of HCl product. In conjunction with the kinetic measurements, a comparison of the HCl signal heights from pairs of measurements on normal and selectively deuterated systems has allowed the determination of the branching fractions of the reactions at the primary, secondary (propane) and tertiary (isobutane) positions. The kinetic data (all in units of cm(3) molecule(-1) s(-1)) for the reaction of Cl atoms with propane ((1.22 +/- 0.02) x10(-10), 195 K; (1.22 +/- 0.03) x10(-10) 298 K) and isobutane ((1.52 +/- 0.02) x10(-10), 195 K; (1.25 +/- 0.04) x10(-10), 298 K) are generally in good agreement with literature data. No data are available for comparison with our measurements for the reactions of Cl atoms with CH(3)CD(2)CH(3) ((1.02 +/- 0.03) x10(-10), 195 K; (1.09 +/- 0.02) x10(-10), 298 K) or (CH(3))(3)CD ((1.32 +/- 0.03) x10(-10), 195 K; (1.12 +/- 0.04) x10(-10), 298 K). Rate coefficients at 195 K for the reactions of Cl atoms with ethane ((5.04 +/- 0.08) x10(-11) and n-butane ((2.19 +/- 0.03) x10(-10)) were also measured. The branching fractions for abstraction at the primary position increased with temperature for both propane ((40 +/- 3)% at 195 K to (48 +/- 3)% at 298 K) and isobutane ((49 +/- 4)% at 195 K to (62 +/- 5)% at 298 K). The direct measurements from this study are in good agreement with most calculations based on structure activity relationships.

Usefulness of reversed display of soft-copy abdominal radiographs for urinary calculi detection

PURPOSE

To determine the usefulness of reversed display of soft-copy abdominal radiographs for urinary calculi detection.

MATERIAL AND METHODS

Sixty radiographs with a single urinary calculus less than 5 mm in the long diameter (15 in the kidney; 15 in the proximal ureter; 15 in the mid-ureter, 15 in the distal ureter) and 15 radiographs without calculi were evaluated. Four readers blinded to the presence or absence of urinary calculi on each radiograph reviewed the radiographs in the conventional display, reversed display, and combination of conventional and reversed displays at 1-week intervals. All images were evaluated in random order and the presence or absence of urinary calculi was interpreted using the confidence score from 1 to 5.

RESULTS

Multireader analysis for calculi in all locations showed a greater area under the receiver operating curve for combination of the two displays (0.764) than for the conventional display alone (0.655) (P=0.031). In the single-reader analysis for calculi in all locations, the third reader showed a greater area under the receiver operating curve for the reversed display (0.784) than for the conventional display (0.622) (P=0.027). Multireader analysis of the calculi in the kidney showed a greater area under the receiver operating curve for combination of the two displays (0.824) than for the conventional display alone (0.703) (P=0.043).

CONCLUSION

The reversed display of soft-copy abdominal radiographs may be useful for urinary calculi detection.

RecA-double stranded DNA complexes studied by atomic force microscopy

RecA-double stranded (ds) DNA complexes have been studied by atomic force microscopy (AFM). When the complexes were prepared in the presence of ATP gamma S, fully covered RecA-dsDNA filaments were observed by AFM. When the concentration of RecA proteins was lower, various lengths of filaments were found. The variation of the observed structures may directly reflect the real distribution of the intermediate complexes in the reaction mixture, as the mixture was simply deposited on a mica surface for AFM observation without special fixation or staining. The use of a carbon nanotube (CNT) AFM tip enabled high resolution to reveal the periodicity of RecA-dsDNA filaments. Our observations demonstrated the potential of the AFM method for the structural studies of the RecA-dsDNA complexes, especially their intermediate states.

A method of calculating a lung clinical target volume DVH for IMRT with intrafractional motion

The motion of lung tumors from respiration has been reported in the literature to be as large as 1-2 cm. This motion requires an additional margin between the Clinical Target Volume (CTV) and the Planning Target Volume (PTV). In Intensity Modulated Radiotherapy (IMRT), while such a margin is necessary, the margin may not be sufficient to avoid unintended high and low dose regions to the interior on moving CTV. Gated treatment has been proposed to improve normal tissues sparing as well as to ensure accurate dose coverage of the tumor volume. The following questions have not been addressed in the literature: (a) what is the dose error to a target volume without a gated IMRT treatment? (b) What is an acceptable gating window for such a treatment. In this study, we address these questions by proposing a novel technique for calculating the three-dimensional (3-D) dose error that would result if a lung IMRT plan were delivered without a gated linac beam. The method is also generalized for gated treatment with an arbitrary triggering window. IMRT plans for three patients with lung tumors were studied. The treatment plans were generated with HELIOS for delivery with 6 MV on a CL2100 Varian linear accelerator with a 26 pair MLC. A CTV to PTV margin of 1 cm was used. An IMRT planning system searches for an optimized fluence map phi(x,y) for each port, which is then converted into a dynamic MLC file (DMLC). The DMLC file contains information about MLC subfield shapes and the fractional Monitor Units (MUs) to be delivered for each subfield. With a lung tumor, a CTV that executes a quasiperiodic motion z(t) does not receive phi(x,y), but rather an Effective Incident Fluence EIF(x,y). We numerically evaluate the EIF(x,y) from a given DMLC file by a coordinate transformation to the Target's Eye View (TEV). In the TEV coordinate system, the CTV itself is stationary, and the MLC is seen to execute a motion -z(t) that is superimposed on the DMLC motion. The resulting EIF(x,y) is input back into the dose calculation engine to estimate the 3-D dose to a moving CTV. In this study, we model respiratory motion as a sinusoidal function with an amplitude of 10 mm in the superior-inferior direction, a period of 5 s, and an initial phase of zero.