Final analysis of phase II results with cemiplimab in metastatic basal cell carcinoma after hedgehog pathway inhibitors.

BACKGROUND: Metastatic basal cell carcinoma (mBCC) is a rare condition with no effective second-line treatment options. Cemiplimab is an immune checkpoint inhibitor that blocks the binding of programmed cell death-1 (PD-1) to its ligands, programmed death-ligand 1 (PD-L1) and programmed death-ligand 2 (PD-L2). Here, we present the final analysis of cemiplimab in patients with mBCC after first-line hedgehog pathway inhibitor (HHI) treatment (NCT03132636). PATIENTS AND METHODS: In this open-label, single-arm, phase II study, adults with mBCC and Eastern Cooperative Oncology Group performance status ≤1, post-HHI treatment, received cemiplimab 350 mg intravenously every 3 weeks for ≤93 weeks or until disease progression or unacceptable toxicity. The primary endpoint was objective response rate (ORR) by independent central review (ICR). Duration of response (DOR) was a key secondary endpoint. Other secondary endpoints were ORR per investigator assessment, progression-free survival (PFS), overall survival (OS), complete response rate, safety, and tolerability. RESULTS: Fifty-four patients were enrolled: 70% were male and the median age of patients was 64 [interquartile range (IQR) 57.0-73.0] years. The median duration of follow-up was 8 months (IQR 4-21 months). The ORR per ICR was 22% [95% confidence interval (CI) 12% to 36%], with 2 complete responses and 10 partial responses. Among responders, the median time to response per ICR was 3 months (IQR 2-7 months). The estimated median DOR per ICR was not reached [95% CI 10 months-not evaluable (NE)]. The disease control rate was 63% (95% CI 49% to 76%) per ICR and 70% (95% CI 56% to 82%) per investigator assessment. The median PFS per ICR was 10 months (95% CI 4-16 months); the median OS was 50 months (95% CI 28 months-NE). The most common treatment-emergent adverse events were fatigue [23 (43%)] and diarrhoea [20 (37%)]. There were no treatment-related deaths. CONCLUSIONS: Cemiplimab demonstrated clinically meaningful antitumour activity, including durable responses, and an acceptable safety profile in patients with mBCC who had disease progression on or intolerance to HHI therapy.

The appearance of dextranomer-hyaluronic acid copolymer implants on ultrasound may predict resolution of vesicoureteral reflux after injection therapy.

AIM: To investigate the correlation between implant appearance on ultrasound (US) and voiding cystourethrography (VCUG) results after dextranomer-hyaluronic acid copolymer (DxHA) injection in children with vesicoureteral reflux (VUR). MATERIALS AND METHODS: Consecutive cases of primary VUR treated by endoscopic subureteral injection of DxHA were retrospectively reviewed. All children had postoperative bladder US and VCUG with a mean interval of 34 days and 47 days after injection, respectively. VUR resolution at postoperative VCUG was considered as treatment success. Implant appearance on US was graded according to the retained volume and its location by visual inspection; it was then correlated with VCUG results using the Spearman correlation coefficient. RESULTS: A total of 36 children (56 ureters) were identified in which 38 ureters (68%) had a clearly visualized implant on postoperative US and 40 ureters (71%) showed VUR resolution. The sensitivity of implant visualization on US for predicting reflux resolution was 73% (29/40), specificity 44% (7/16), positive predictive value 76% (29/38), and negative predictive value 39% (7/18). The grade 1, grade 2, and grade 3 implant appearances showed VUR resolution in 88% (22/25), 54% (7/13), and 61% (11/18), and showed persistent VUR in 8% (2/25), 15% (2/13), and 28% (5/18), respectively (p = 0.032). CONCLUSION: The implant appearance on postoperative US showed good correlation with VCUG results in the early post-injection period. Large retained implants were associated with treatment success, while small or non-visualized implants were related to the persistent reflux.

Hepatic tumours in children with biliary atresia: single-centre experience in 13 cases and review of the literature.

AIM: To establish the risks of developing of hepatic tumours and to investigate their clinical and imaging findings in children with biliary atresia (BA) after Kasai portoenterostomy (Kasai). MATERIALS AND METHODS: Among 157 children who had undergone Kasai for BA over an 18 year period, patients who had newly developed hepatic tumours were identified. Patient demographics, clinical features, and imaging findings were retrospectively reviewed. RESULTS: Three male and 10 female patients (mean age 3.9 years) all (8%, of 157) had single hepatic tumours, which were confirmed in 10 explanted and three non-explanted livers. Ten (77%) were benign and three (23%) were malignant. Of the benign hepatic tumours, focal nodular hyperplasia (FNH; n = 6) was the most common, followed by regenerative nodules (n = 3) and adenoma (n = 1). All FNH appeared in young children <1 year of age and showed a subcapsular location, bulging contour, and lack of central scar. Malignant tumours included two hepatocellular carcinomas and one cholangiocarcinoma. CONCLUSION: Hepatic tumours developed in approximately 8% of children with BA after Kasai. Although benign tumours, including FNHs and regenerative nodules, were more common than malignant tumours, screening with alpha-foetoprotein (AFP) levels and regular imaging studies are the mainstay of malignant tumour detection.

Serial ultrasound findings associated with early liver transplantation after Kasai portoenterostomy in biliary atresia.

AIM: To investigate the ultrasound findings associated with early liver transplantation (LT) after Kasai portoenterostomy (Kasai) in children with biliary atresia (BA). MATERIALS AND METHODS: Children with BA (n = 30) who underwent Kasai were classified into early LT group (n = 17, LT within 1 year after Kasai) and Kasai alone group (n = 13, alive with their native livers). Serial ultrasound (baseline and follow-up before LT or post-Kasai 1 year) images were reviewed to investigate significant ultrasound findings related to early LT using both univariate and multivariate models. Images were reviewed focusing on the hepatic artery diameter, portal vein diameter, and signs of portal hypertension. RESULTS: The hepatic artery diameters in the early LT group were significantly larger than those in the Kasai alone group both at baseline (p = 0.007) and follow-up ultrasound (p < 0.001). The portal vein diameters on follow-up ultrasound were smaller in the early LT group than the Kasai alone group (p < 0.001). On multivariate analysis, baseline hepatic artery diameter (hazard ratio, 20.4; 95% confidence interval, 3.7-110.6; p < 0.001) and the presence of splenomegaly at follow-up ultrasound (17.7; 2.6-121.8; p = 0.004) were significant predictors associated with early LT. The optimal cut-off value of the baseline hepatic artery diameter was 1.9 mm (82% sensitivity and 77% specificity). CONCLUSION: Enlarged hepatic artery at baseline ultrasound and the presence of splenomegaly at follow-up ultrasound were associated with early LT after Kasai in children with BA.

Aberrant cervical thymus: imaging and clinical findings in 13 children.

AIM: To investigate the imaging and clinical findings of aberrant cervical thymus, especially validating the usefulness of ultrasound (US). MATERIALS AND METHODS: The imaging and clinical findings of 13 children with aberrant cervical thymus were reviewed. Imaging studies were investigated for the location, size, composition, and shape with special emphasis on US characteristics. Medical records were reviewed for patient demographics, clinical presentations, and management. RESULTS: There were 10 male and three female patients (age range 1 month to 12 years; mean 3 years). Nine children (69%) were younger than 1 year. The most common presenting symptom or sign was palpable, cervical, non-tender mass or swelling. The most common site was the submandibular area. The mean of the maximal diameter was 3.5 cm (range 1.5-10 cm). The composition was solid (n=12) and solid and cystic (n=1). All lesions showed well-defined, angular margins with moulding over adjacent structures. On US, the echogenicity of the solid portion was identical to that of the mediastinal thymus in all cases, demonstrating the characteristic internal echo pattern. CONCLUSION: Although rare, aberrant cervical thymus usually occurs as a well-defined, solid mass most frequently at the submandibular area in infants and young children. US is indicated as the initial imaging mode for assessment and may be the only technique required.

H1N1 influenza infection in children: Frequency, pattern, and outcome of chest radiographic abnormalities.

AIM: To describe the frequency, pattern, and outcome of chest radiographic abnormalities in children with H1N1 influenza infection. MATERIALS AND METHODS: Three hundred and fourteen paediatric patients with confirmed H1N1 influenza infection who underwent chest radiography at presentation at a single institution during the outbreak in 2009 were retrospectively reviewed. Abnormal chest radiographic findings related to acute infection were analysed in terms of frequency, pattern, and distribution. Medical records and follow-up radiographs were also reviewed to assess clinical features and outcomes. RESULTS: Chest lesions suggesting acute infection were identified in 49 (16%) patients (mean age 8.2 years, range approximately 1.8-18.5 years). The most common finding was prominent peribronchial marking (71%), followed by air-space opacity (51%) with or without volume decrease, generalized hyperinflation (24%), and pleural effusion (20%). Other minor findings included pneumomediastinum (n=2) and a nodule (n=1). Distributions were bilateral (55%) or unilateral (45%) with frequent involvement of lower (78%), and middle (59%) lung zones. Thirty-nine patients (80%) were hospitalized and six (12%) required mechanical ventilation, followed by recovery. Thirty-one out of the 33 patients that underwent follow-up radiography showed marked resolution of all radiographic abnormalities. CONCLUSION: The frequency of a chest radiographic abnormality was found to be low in children with H1N1 influenza infection. Although typical radiographic findings of a viral lower respiratory infection were more common, unilateral involvement and air-space opacity were common, often with pleural effusion. Furthermore, pulmonary lesions showed near complete resolution on follow-up radiographs in the majority of patients.

Atypical teratoid/rhabdoid tumors of the central nervous system: imaging and clinical findings in 16 children.

AIM: To investigate the imaging and clinical findings of central nervous system (CNS) atypical teratoid/rhabdoid tumours (AT/RTs) in children. MATERIALS AND METHODS: The computed tomography (CT) and magnetic resonance imaging (MRI) findings and clinical records of 16 children with CNS AT/RTs were retrospectively reviewed. Tumour location, size, composition, enhancement pattern, peritumoural oedema, signal intensity (SI) on MRI and CT attenuation were evaluated. RESULTS: A total of 17 lesions from 16 patients (median age 2.3 years, age range 0.7-15 years) were included in the evaluation. Tumour location was infratentorial for 11 lesions and supratentorial for six lesions. The mean diameter of the largest dimension for a tumour was 4 cm. The tumour was mainly solid in 65% of cases, and solid and cystic or cystic and solid in 35% of cases. The solid component of the tumours had a homogeneous iso SI (n=15) on T2-weighted MRI images and iso SI (n=14) on T1-weighted images. Moderate to strong enhancement of the solid component was noted in most cases. In spite of a large tumour size, peritumoural oedema was minimal or mild except in four cases. Rapid growth of the tumour was demonstrated in three cases. Seven patients died from tumour progression, with a mean survival time of 8.4 months (range 2-12 months). CONCLUSION: Although the AT/RTs had non-specific imaging findings, the tumours tended to be large in size, have iso SI on T1 and T2-weighted MR images with prominent enhancement, and relatively mild peritumoural oedema. Rapid growth of the tumour was seen during the follow-up period.

Heterogeneity in the processing defect of SLC26A4 mutants.

BACKGROUND: Mutations in the SLC26A4 gene are responsible for Pendred syndrome and non-syndromic hearing loss (DFNB4). This study analysed non-synonymous SLC26A4 mutations newly identified in East Asians, as well as three common mutations in Caucasians, to characterise their molecular pathogenic mechanisms and to explore the possibility of rescuing their processing defects. METHODS: A total of 11 non-synonymous disease associated mutations were generated and their effects on protein processing and on ion transporting activities were examined. RESULTS: Most of the mutations caused retention of the SLC26A4 gene product (pendrin) in the intracellular region, while wild-type pendrin reached the plasma membrane. Accordingly, these mutations abolished complex glycosylation and Cl(-)/HCO(3)(-) exchange activities of pendrin. However, significant heterogeneity in the processing of mutant pendrin molecules was observed. Each mutant protein exhibited a different cellular localisation, a different degree of N-glycosylation, and a different degree of sensitivity to the treatments that rescue processing defects. For example, H723R-pendrin, the most common mutation in East Asians, was mostly expressed in endoplasmic reticulum (ER), and its defects in protein processing and ion transporting activities were restored considerably by low temperature incubation. On the other hand, L236P-pendrin, the most common mutation in Caucasians, was mainly in the centrosomal region and was temperature insensitive. CONCLUSION: These results indicate that the processing of pendrin mutant protein is determined by mutant specific mechanisms, and that a mutant specific method would be required to rescue the conformational defects of each folding mutant.

A quantitative analysis of heterogeneities and hallmarks in acute myelogenous leukaemia.

Acute myelogenous leukaemia (AML) is associated with risk factors that are largely unknown and with a heterogeneous response to treatment. Here, we provide a comprehensive quantitative understanding of AML proteomic heterogeneities and hallmarks by using the AML Proteome Atlas, a proteomics database that we have newly derived from MetaGalaxy analyses, for the proteomic profiling of 205 patients with AML and 111 leukaemia cell lines. The analysis of the dataset revealed 154 functional patterns based on common molecular pathways, 11 constellations of correlated functional patterns and 13 signatures that stratify the outcomes of patients. We find limited overlap between proteomics data and both cytogenetics and genetic mutations. Moreover, leukaemia cell lines show limited proteomic similarities with cells from patients with AML, suggesting that a deeper focus on patient-derived samples is needed to gain disease-relevant insights. The AML Proteome Atlas provides a knowledge base for proteomic patterns in AML, a guide to leukaemia cell line selection, and a broadly applicable computational approach for quantifying the heterogeneities of protein expression and proteomic hallmarks in AML.

Loss of asymmetry in D2 receptors of putamen in unaffected family members at increased genetic risk for schizophrenia.

OBJECTIVE: Dopamine dysregulation has been implicated in the pathophysiology of schizophrenia. The present study was performed to examine whether unaffected relatives at high genetic risk of schizophrenia have dopamine dysregulation in comparison with healthy controls. METHOD: Eleven unaffected relatives from families with two or more first- or second-degree relatives with schizophrenia (n = 9) or with a monozygotic schizophrenic twin (n = 2) and 11 age- and sex-matched controls were examined using positron emission tomography (PET) with [(11)C] raclopride. Subjects also underwent extensive neuropsychological testing. RESULTS: Subjects with high genetic risk showed a loss of asymmetry of D(2) receptors in the putamen in comparison with healthy controls. In addition, they showed significantly poorer performance on neuropsychological tests than controls. CONCLUSION: Our results suggest that dopamine dysregulation and neuropsychological dysfunction may be present in subjects at high genetic risk of schizophrenia. However, further studies are required to confirm these findings.

Modeling of brain D2 receptor occupancy-plasma concentration relationships with a novel antipsychotic, YKP1358, using serial PET scans in healthy volunteers.

YKP1358 is a novel serotonin (5-HT(2A)) and dopamine (D(2)) antagonist that, in preclinical studies, fits the general profile of an atypical antipsychotic. We conducted a D(2) receptor occupancy study with YKP1358 in healthy volunteers using positron emission tomography (PET) to measure the D(2) receptor occupancy of YKP1358 and to characterize its relationship to plasma drug concentrations. A single oral dose, parallel group, dose-escalation (100, 200, and 250 mg) study was performed in 10 healthy male volunteers with the PET radiotracer [(11)C]raclopride. The D(2) receptor occupancy of striatum was measured pre-dose, and at 2, 5, and 10 h after YKP1358 administration. Serial blood samples were taken for measurement of plasma YKP1358 concentrations. D(2) receptor occupancy by YKP1358 increased to 53-83% at 2 h, and then decreased afterwards, ranging from 40-64% at 5 h to 20-51% at 10 h. The YKP1358 dose-plasma concentration relationship exhibited extensive variability, but there was a good relationship between plasma concentrations and D(2) receptor occupancy that was well predicted by a sigmoid E(max) model using nonlinear mixed effects modeling. To our knowledge, this is the first study in which the relationship between plasma concentration and the biomarker of D(2) receptor occupancy was modeled using nonlinear mixed effects modeling. It is anticipated that these results will be useful in estimating for subsequent studies the initial doses of YKP1358 required to achieve a therapeutically effective range of D(2) receptor occupancy.

Increased induction of Ca2+-mediated differentiation by gamma ray is mediated by endogenous activation of the protein kinase C signaling pathways in mouse epidermal cells.

PURPOSE: The aim of this study was to determine whether gamma-rays can affect Ca2+-induced differentiation in normal and neoplastic mouse epidermal cells. METHODS AND MATERIALS: After gamma-ray irradiation, primary and v-rasHa transformed mouse keratinocytes were cultured for 48 h in 0.12 mM Ca2+-containing media, and cellular translocation from cytosolic to particulated fraction of each PKC isozyme and expressions of differentiation markers were examined. RESULTS: Morphological difference was seen at 48 h after irradiation in both Ca2+-shifted normal and v-rasHa transformed cells; v-rasHa cells were more resistant to the radiation than normal cells. Radiation potentiated granular cell-differentiation marker expressions (filaggrin, loricrin, and SPR-1) in both normal and v-rasHa transformed cells. In the case of spinous cell markers, the expression of keratins K1 and K10, which are usually blocked in v-rasHa cells was increased after irradiation. However, there was no change of K8 expression level, which can be seen only after v-rasHa transfection. Cellular fractionation and immunoblot analysis with antibodies against PKCalpha, delta, epsilon, eta, and xi revealed that PKCalpha was responsible for the differentiation marker expression. CONCLUSIONS: These findings suggest that PKCalpha is an important component of the signaling pathway regulating radiation-induced differentiation in both normal and neoplastic epidermal cells.

Enhancement of radiation-induced hepatic microsomal epoxide hydrolase gene expression by oltipraz in rats.

The effects of radiation exposure in conjunction with oltipraz, a chemopreventive agent, on the expression of the gene encoding hepatic microsomal epoxide hydrolase (mEH) were examined in rats. Rats exposed to a single dose of 3 Gy gamma rays exhibited timerelated changes in the hepatic mEH mRNA level. Whereas the mEH mRNA level was transiently decreased at 3 and 8 h after irradiation, the mRNA levels were increased 3- to 4-fold at 15 to 48 h postirradiation, returning to the level in untreated animals at 72 h. Treatment of rats with oltipraz resulted in 1- to 19-fold increases in hepatic mEH mRNA levels 24 h post-treatment at doses of 5-200 mg/kg. Although treatment with oltipraz at a dose of 30 mg/kg affected the mEH mRNA level minimally (i.e. approximately 2-fold), 3 Gy whole-body irradiation along with oltipraz treatment resulted in a 9-fold increase in the mEH mRNA level at 24 h post-treatment. Treatment of animals with both oltipraz and 3 Gy gamma radiation for 3 consecutive days resulted in a 7-fold increase in mEH mRNA, showing that the increases in mEH mRNA were enhanced by the combination treatment. In rats irradiated with 3 Gy for 5 consecutive days, however, the mEH mRNA level failed to increase due to cell injury. Studies were further designed to assess the effects of 0.5 Gy ionizing radiation and concomitant oltipraz treatment. RNA blot analysis showed that mEH mRNA levels failed to be significantly altered at 3, 8, 15, 24 and 48 h after a single dose of 0.5 Gy. Nonetheless, exposure of animals to 0.5 Gy daily for 3 to 5 consecutive days caused a 3-fold elevation in the hepatic mEH mRNA level. Furthermore, treatment of animals with both oltipraz (30 mg/kg/day) and 0.5 Gy of gamma rays resulted in an enhanced elevation in the mEH mRNA level at 24 h post-treatment compared to the individual treatment, resulting in a 7-fold relative increase. The enhanced expression of hepatic mEH mRNA by 0.5 Gy gamma radiation and oltipraz was also observed after treatment for 3 to 5 days (8- to 6-fold relative increases). Western immunoblot analyses showed that hepatic microsomes produced from the rats treated with 0.5 Gy daily for 3 to 5 days resulted in a approximately 2-fold induction of hepatic mEH and that rats exposed to radiation in combination with oltipraz showed 3-fold increases in the liver mEH protein. Thus the relative increase in mEH mRNA levels was consistent with the expression of the protein. These results demonstrate that ionizing radiation causes alterations in hepatic mEH gene expression with the induction of the protein and that the mEH gene expression is enhanced by oltipraz treatment.

Inducible heat-shock protein 70 is involved in the radioadaptive response.

Park, S-H., Lee, S-J., Chung, H-Y., Kim, T-H., Cho, C-K., Yoo, S-Y. and Lee, Y-S. Inducible Heat-Shock Protein 70 Is Involved in the Radioadaptive Response. The thermoresistant (TR) clone of radiation-induced fibrosarcoma (RIF) cells showed an adaptive response, i.e. a reduced effect, after exposure to a higher challenging dose (4 Gy) when the priming dose (1 cGy) was given 4 or 7 h earlier, but RIF cells did not. Since inducible Hsp70 expression was different in cells of these two cell lines, the role of inducible Hsp70 in the adaptive response was examined. When inducible Hsp70 was transfected into RIF cells, the adaptive response was acquired. Transfection of inducible Hsp70 to NIH 3T3 mouse embryo cells also conferred radioresistance to the cells as assayed by clonogenic survival, [(3)H]thymidine incorporation, and an ELISA cell death detection kit. An increased tendency for the induction of an adaptive response was also observed. Interestingly, basal levels of Ca(2+)-dependent and independent Pkc activities were increased by transfection with inducible Hsp70 compared to those of control vector cells. Irradiation with gamma rays induced activation of Pkc within minutes in control vector cells, while transfection with inducible Hsp70 did not. Cellular redistribution to particulate fractions of Pkca, d and z after exposure gamma rays also was not detected. Furthermore, radioresistance by transfection with inducible Hsp70, as tested by clonogenic survival, disappeared after pretreatment with Pkc inhibitors, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H7), prolonged treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA), and GF109203X. Taken together, these data suggest that radioresistance inducible by Hsp70 is associated with an elevated level of Pkc activity.

Hsp25-induced radioresistance is associated with reduction of death by apoptosis: involvement of Bcl2 and the cell cycle.

We previously demonstrated the protective effect of the small heat-shock protein against oxidative damage induced by tumor necrosis factor alpha. Here we have extended our studies of the possible role of Hsp25 in ionizing radiation-induced damage. For these studies, we transfected murine fibroblast L929 cells with the Hsp25 gene and selected three stably transfected clones. Hsp25 overexpression conferred radioresistance as detected by clonogenic survival and induction of apoptosis. Interestingly, the Hsp25-transfected cells showed an increase in the level of the anti-apoptosis molecule Bcl2. We also observed alterations of cell growth in the Hsp25-transfected cells. The cell cycle time of Hsp25-transfected cells was 3-4 h slower than that of vector-transfected control cells. Flow cytometry analysis of synchronized cells at late G(1) phase by mimosine treatment also showed the growth delay in Hsp25-overexpressing cells. In addition, reduced cyclin D1, cyclin A and Cdc2 levels and increased levels of Cdkn1a (also known as p21(Waf)) were observed in Hsp25-transfected cells, which probably caused the reduction in cell growth. In addition, synchronization by mimosine treatment only partially altered radioresistance in the Hsp25-transfected cells. Taken together, these data suggest that Hsp25-induced radioresistance is associated with growth delay as well as induction of Bcl2.

Protective effects of potato extracts and 16,16-dimethyl prostaglandin E2 on the induction of hepatic foci by cotreatment of gamma radiation and diethylnitrosamine.

We investigated the effect of potato extracts and 16,16-dimethyl prostaglandin E2 (DiPGE2) on the induction of glutathione S-transferase P-positive (GST-P+) altered hepatic foci in newborn Sprague-Dawley rats given single treatment with 60Co gamma irradiation and diethylnitrosamine (DEN) alone or in sequential combination. Intraperitoneal injection of 0.15 mumol/g body weight of DEN 1 hour after gamma radiation significantly increased the frequencies of GST-P+ hepatic foci compared to DEN or gamma radiation alone and DEN injection 1 hour before irradiation (p < 0.001). Potato extract was given at a dose of 2 mg/ml in drinking water for 3 weeks and DiPGE2 given at a dose of 10 micrograms/mouse 30 minutes before irradiation. Potato extracts and DiPGE2 decreased significantly the number (p < 0.001), area (p < 0.001) and Dmax (p < 0.05) of GST-P+ hepatic foci compared to the corresponding control. These results suggest that potato extracts and DiPGE2 have radio-protective potential and further studies for underlying mechanisms will be necessary.

Measurement of apoptotic fragments in growing hair follicles following gamma-ray irradiation in mice.

The usefulness of apoptotic fragments assay for investigating radiation response of hair follicles was examined. Frequency was defined as the ratio of the total number of apoptotic fragments to the number of hair follicles per section examined. The curve of dose-effect relationship for the data of apoptotic fragments was obtained by fitting the linear-quadratic model y= a+bD+cD2. When plotting on a linear scale against radiation dose, the line of best fit was y= 0.549 +/- 1.775) + 3.578 +/- 1.236)D + (-0.124 +/- 0.139)D2. The dose-response curves were linear-quadratic and a significant relationship was found between the frequency of apoptotic fragments and dose. The morphological findings of the irradiated groups were typical apoptotic fragments in the matrix region of hair follicles, but the spontaneous occurrence of apoptotic fragments was not observed. Since the apoptotic fragments was not observed. Since the apoptotic fragment assay is simple and reproducible in the whole body irradiation range of 0.5 to 8 Gy, it may be a good tool for evaluating the dose response of low dose radiation in vivo and provide a potentially valuable biological dosimeter for dose distribution determinations following accidental exposure.

Frequency of micronuclei in lymphocytes following gamma and fast-neutron irradiations.

The dose response of the number of micronuclei in cytokinesis-blocked (CB) lymphocytes after in vitro irradiation with y-rays and neutrons in the 5 dose range was studied in a heterogeneous population of 4 donors. One thousand binucleated cells were systematically scored for micronuclei. Measurements performed after irradiation showed a dose-related increase in micronuclei (MN) frequency in each of the donors studied. The dose-response curves were analyzed by a linear-quadratic model; frequencies per 1000 CB cells were (0.31 +/- 0.049)D + (0.0022 +/- 0.0002)D2 + (13.19 +/- 1.854) (r2 = 1.000, x2 = 0.7074, p = 0.95) following y-irradiation, and (0.99 +/- 0.528)D + (0.0093 +/- 0.0047)D2 + (13.31 +/- 7.309) (r2 = 0.996, x2 = 7.6834, p = 0.11) following neutron irradiation (D is irradiation dose in cGy). The relative biological effectiveness (RBE) of neutrons compared with y-rays was estimated by best fitting linear-quadratic model. In the micronuclei frequency between 0.05 and 0.8 per cell, the RBE of neutrons was 2.37 +/- 0.17. Since the MN assay is simple and rapid, it may be a good tool for evaluating the y-ray and neutron response.

Influence of ionizing radiation on induction of apoptotic cell death and cellular redistribution of protein kinase C isozymes in mouse epidermal cells differing in carcinogenesis stages.

Although protein kinase C (PKC) plays an important role in cellular response to radiation, little is known about the specific role of each isoform in the radiation induced cellular response. In this study, the induction of apoptosis and subcellular distribution of PKC isoforms after gamma-ray irradiation were examined in three kinds of mouse epidermal cells with different stages of carcinogenesis (normal mouse keratinocytes, PK: v-rasHa transfected mouse keratinocytes, ras-PK; and neoplastic cells from mouse skin papilloma, 308 cells). The induction of apoptosis was different in normal and neoplastic cells; in normal cells after 16 Gy of radiation, apoptosis was 2-10 times higher than that in ras-PK or 308 cells, and was rapidly induced; other cells died more slowly, depending on the stage of carcinogenesis. The responses of each PKC, especially rapid translocation of PKCdelta and no response of PKCepsilon by radiation in normal cells may influence the induction of apoptosis by radiation.

Protein biosynthesis in low dose ionizing radiation-adapted human melanoma cells.

Adaptive responses induced by low dose gamma-ray irradiation in human melanoma cells were examined using a clonogenic assay. Survival fractions were significantly increased in cells irradiated with low dose gamma-rays then 4 hrs later with high dose gamma-ray as compared to cells irradiated only with high dose gamma-rays. When low dose irradiation was given 20 hrs prior to high dose irradiation, however, no adaptive response was induced. Changes in protein biosynthesis in human melanoma cells were observed under the same conditions. Significant changes in protein biosynthesis occurred in the nuclear and membrane proteins of cells first irradiated with a low dose then a high dose of gamma-rays after 4 hrs. No such changes were found in cells irradiated with low dose gamma-rays 20 hrs prior to high dose irradiation, consistent with the results of the clonogenic assay. Our findings suggest that prior treatment with low dose gamma-rays induces an adaptive response that has a significant effect on the induction of the nuclear and membrane protein biosynthesis caused by high dose gamma-ray irradiation of human melanoma cells.