Accelerating space radiation countermeasure development through drug repurposing.

The discovery of safe and effective radiation countermeasures (MCM) for long-duration spaceflight is challenging due to the complexity of the space radiation biology and high safety requirements. There are few if any clinically-validated molecular targets for this use case, and preclinical models have several known limitations. These challenges make the evaluation of existing FDA-approved drugs for this indication, or drug repurposing, an attractive strategy to accelerate space radiation countermeasure development. Drug repurposing offers several advantages over de novo drug discovery including established manufacturing methods, human clinical safety data, and well-understood dosing and pharmacokinetic considerations. There are limitations working with a fixed set of possible candidate compounds, but some properties of repurposed drugs can be tailored for well-defined new indications through reformulation and development of drug combinations. Drug repurposing is thus an attractive strategy for mitigating the high risks and costs of drug development and delivering new countermeasures to protect human from space radiation in long-term missions.

The potential of mesenchymal stem cells in the management of radiation enteropathy.

Although radiotherapy is effective in managing abdominal and pelvic malignant tumors, radiation enteropathy is still unavoidable. This disease severely affects the quality of life of cancer patients due to some refractory lesions, such as intestinal ischemia, mucositis, ulcer, necrosis or even perforation. Current drugs or prevailing therapies are committed to alleviating the symptoms induced by above lesions. But the efficacies achieved by these interventions are still not satisfactory, because the milieus for tissue regeneration are not distinctly improved. In recent years, regenerative therapy for radiation enteropathy by using mesenchymal stem cells is of public interests. Relevant results of preclinical and clinical studies suggest that this regenerative therapy will become an attractive tool in managing radiation enteropathy, because mesenchymal stem cells exhibit their pro-regenerative potentials for healing the injuries in both epithelium and endothelium, minimizing inflammation and protecting irradiated intestine against fibrogenesis through activating intrinsic repair actions. In spite of these encouraging results, whether mesenchymal stem cells promote tumor growth is still an issue of debate. On this basis, we will discuss the advances in anticancer therapy by using mesenchymal stem cells in this review after analyzing the pathogenesis of radiation enteropathy, introducing the advances in managing radiation enteropathy using regenerative therapy and exploring the putative actions by which mesenchymal stem cells repair intestinal injuries. At last, insights gained from the potential risks of mesenchymal stem cell-based therapy for radiation enteropathy patients may provide clinicians with an improved awareness in carrying out their studies.

Vesico-cutaneous fistula: a simple method for continent urinary diversion.

INTRODUCTION: Patients with lower urinary tract anomalies or neurogenic disorders often suffer from voiding difficulties. Clean intermittent catheterization (CIC) is effective for bladder drainage; however, this is often painful. Transurethral catheterization is also impossible in patients with urethral stricture. A Mitrofanoff conduit may solve some of these problems, but a few disadvantages have been reported, including: difficult surgical techniques and frequent operative complications. A vesicostomy is easy to perform but persistent urine leak over the abdomen and diaper rash can be annoying. A better way to achieve continent urinary diversion is indicated. METHOD: Between December 01 1998 and December 31 2013, six patients underwent a vesico-cutaneous fistula for CIC. The etiologies included urethral stricture (n=2) and neurogenic bladder (n=4). The fistula was created at the bladder dome with only the muscle layer of the bladder sutured to the skin. A Foley catheter was left in place for at least two weeks to prevent stoma stricture. After removing the Foley catheter, regular CIC from the fistula was performed every 2 h during the daytime with a Fr. 10-12 feeding tube, depending on the patient's age. Further stenting during the night in the first six months was necessary to prevent early closure of the fistula. Patients were followed with periodic renal ultrasonography, blood tests and urinalysis in the outpatient department. RESULTS: Follow-up ranged from 6 months to 16 years. All patients showed improvements in hydronephrosis. Decreased UTI frequency was seen in five patients. Renal function was normal in five patients, whilst the other suffered from chronic renal failure preoperatively. Only one patient had occasional mild urine leakage from the stoma at night, which was once in two weeks. No patient experienced painful or difficult catheterization and CIC becomes easy, even by young children. CONCLUSIONS: The vesico-cutaneous fistula is a simple, effective and tolerable method for CIC. It may be a substitute for or a transition to a Mitrofanoff conduit in some patients.

Outcomes after surgery in patients with previous stroke.

BACKGROUND: Limited information is available on the association between a medical history of stroke and postoperative outcomes. This study investigated the outcomes following non-neurological surgery in patients with previous stroke. METHODS: Using Taiwan's National Health Insurance Research Database, a nationwide cohort study was conducted of patients who underwent non-neurological surgery between 2008 and 2010 with a medical history of stroke in the 24-month period before operation. Patients who had non-neurological surgeries without previous stroke were selected as controls by the propensity score-matched pair method. Thirty-day postoperative complications and in-hospital mortality were compared between the two groups. RESULTS: Some 1 426 795 adults underwent major inpatient non-neurological surgery, of whom 45 420 had a medical history of previous stroke. Patients with previous stroke who underwent surgery had an increased risk of postoperative pneumonia, septicaemia, acute renal failure, acute myocardial infarction, pulmonary embolism and 30-day in-hospital mortality (adjusted rate ratio (RR) 1·79, 95 per cent c.i. 1·61 to 1·99). Compared with controls, patients with previous stroke due to intracerebral haemorrhage (RR 3·41, 2·97 to 3·91), and those who were treated in intensive care (RR 2·55, 2·24 to 2·90) or underwent neurosurgery (RR 2·49, 2·12 to 2·92), had an increased 30-day in-hospital mortality rate. Postoperative mortality also increased with stroke-related co-morbidities, and with stroke 1-6 months before surgery (RR 3·31, 2·91 to 3·75). CONCLUSION: Patients with previous stroke had a higher risk of adverse postoperative outcomes; their 30-day in-hospital mortality rate was nearly twice that of patients without previous stroke.

Biological impact of low dose-rate simulated solar particle event radiation in vivo.

C57Bl6-lacZ animals were exposed to a range of low dose-rate simulated solar particle event (sSPE) radiation at the NASA-sponsored Research Laboratory (NSRL) at Brookhaven National Laboratory (BNL). Peripheral blood was harvested from animals from 1 to 12 days after total body irradiation (TBI) to quantify the level of circulating reticulocytes (RET) and micronucleated reticulocytes (MN-RET) as an early indicator of radiation-induced genotoxicity. Bone marrow lymphocytes and hippocampal tissues from each animal were collected at 12 days and up to two months, to evaluate dose-dependent late effects after sSPE exposure. Early hematopoietic changes show that the % RET was reduced up to 3 days in response to radiation exposure but recovered at 12 days postirradiation. The % MN-RET in peripheral blood was temporally regulated and dependant on the total accumulated dose. Total chromosome aberrations in lymphocytes increased linearly with dose within a week after radiation and remained significantly higher than the control values at 4 weeks after exposure. The level of aberrations in the irradiated animals returned to control levels by 8 weeks postirradiation. Measurements of chromosome 2 and 8 specific aberrations indicate that, consistent with conventional giemsa-staining methods, the level of aberrations is also not significantly higher than in control animals at 8 weeks postirradiation. The hippocampus was surveyed for differential transcriptional regulation of genes known to be associated with neurogenesis. Our results showed differential expression of neurotrophin and their associated receptor genes within 1 week after sSPE exposure. Progressive changes in the profile of expressed genes known to be involved in neurogenic signaling pathways were dependent on the sSPE dose. Our results to date suggest that radiation-induced changes in the hematopoietic system, i.e., chromosome aberrations in lymphocytes, are transient and do not persist past 4 weeks after radiation. On the other hand, alteration in the profile of genes known to be involved in neurotrophic functions in the hippocampal tissue appears to persist for up to 8 weeks after radiation exposure. Such temporal changes confirm that, although cytogenetic changes after a single dose of low-dose and low-dose-rate protons appear to be transient, the impact of this exposure is sufficient to lead to persistent dynamic changes in neuronal tissues long after the initial radiation exposure.

Coronary artery air embolism: a potentially fatal complication of CT-guided percutaneous lung biopsy.

CT-guided transthoracic lung biopsy is becoming a widely accepted procedure for the diagnosis of pulmonary lesions. The rate of severe complications following such a procedure has been reported. Of these complications, air embolism is the most likely to be fatal. We report a case of right coronary air embolism resulting in myocardial infarction after a CT-guided percutaneous needle biopsy of the lung. The patient died from underlying malignant disease 4 months later.

Pars plana vitrectomy in the management of paediatric uveitis: the Massachusetts Eye Research and Surgery Institution experience.

PURPOSE: To assess the effectiveness and safety of pars plana vitrectomy (PPV) in the management of chronic paediatric uveitis. METHODS: We reviewed records of patients 16 years old or younger who underwent PPV due to persistent uveitis. Data including inflammatory status, ocular findings, visual acuity, dosage and duration of various medical therapies, surgical techniques and complications were collected. RESULTS: Twenty-eight eyes of 20 patients were included in the study. The diagnoses of uveitis included pars planitis in 15 eyes (54%), idiopathic panuveitis in 8 eyes (29%), and juvenile idiopathic arthritis-associated iridocyclitis in five eyes (18%). Six eyes presented with associated retinal vasculitis. The mean age at the time of PPV was 11.2 years. The mean follow-up after surgery was 13.5 months. All 28 eyes had active uveitis with or without medical therapy at the time of PPV. At last follow-up, uveitis control was achieved with or without adjuvant medical therapy in 27 eyes (96%). These included five of the six eyes with persistent retinal vasculitis. Two eyes that had 20-G PPV developed intra-operative retinal tears. Four eyes with pre-operative clear lenses developed cataract within the first 6 months after PPV. CONCLUSIONS: PPV is effective and safe in the management of chronic paediatric uveitis and its complications. It was able to reduce the amount of systemic medications required to control inflammation in this study. Patients with uveitis complicated by retinal vasculitis, however, are more likely to require long-term medical therapy to achieve inflammatory control.

A method for the non-invasive assessment of chest wall growth in pectus excavatum patients.

INTRODUCTION: Various scales and measurement methods including X-rays and computed tomography (CT) have been used to quantify the degree of deformity in pectus excavatum. This study describes a non-invasive method for recording the deviation of the anterior chest wall (ACW) in pectus excavatum (PE) patients. Data obtained using this non-invasive method were compared with CT data. MATERIALS AND METHODS: Twenty-one patients treated at our institutions between June 2008 and February 2009 were enrolled in this study. All patients underwent CT and thermal plastic strip measurement. A thermal plastic strip was positioned and taped to the supine patient's ACW at the skin level from the posterior axillary line, over the depressed sternum, to the contralateral posterior axillary line and used to create a casting of the ACW. RESULTS: The funnel index (FI) was defined as the width of the ACW divided by its height; the concave index (CI) was defined as the breadth of the depressed area of the funnel chest divided by its depth. Pearson's correlation coefficient was used to compare the FI and CI obtained with the thermal plastic strip method and with CT; measurements obtained with both methods were found to correlate well (FI: r (2)=0.965; CI: r (2)=0.947). CONCLUSIONS: The thermal plastic strip measurement method provides a two-dimensional record of the shape of the anterior chest wall. The measurement can be repeated, does not involve the patient being exposed to radiation, and offers a good longitudinal assessment of chest wall growth in PE patients.

Pars plana vitrectomy for diabetic fibrovascular proliferation with and without internal limiting membrane peeling.

OBJECTIVE: To evaluate the anatomical and functional results of internal limiting membrane (ILM) peeling during pars plana vitrectomy for fibrovascular proliferation (FVP) in diabetic retinopathy. METHODS: The study was a prospective comparative case series in design. Patients undergoing pars plana vitrectomy for mild to moderate diabetic FVP were divided into either Group 1: vitrectomy only, or Group 2: further ILM peeling in the macular area. Best-corrected visual acuity, fundus examination, and optical coherence tomography (OCT) were conducted at 3 and 6 months postoperatively. RESULTS: There were 26 eyes of 25 patients in Group 1 (non-ILM peeling) and 23 eyes of 22 patients in Group 2 (ILM peeling). At 6 months postoperatively, OCT-identifiable epiretinal membrane (ERM) was found in 10 of 26 eyes (38.5%) in Group 1and 0 of 23 eyes in Group 2 (P=0.001) and six eyes (23.1%) in Group 1 developed biomicroscopic ERM, whereas no patients in Group 2 had ERM (P=0.02) at 6 months. OCT identifiable ERM correlated significantly with central macular thickness (r=-0.58, P<0.001), the presence of intraretinal cystic space (r=0.60, P<0.001), and fovea depression reappearance (r=0.36, P=0.008). Factors associated with poor visual outcome were macular detachment (P<0.001) and non-ILM peeling (P=0.004). CONCLUSIONS: This pilot study suggests that ILM peeling during vitrectomy for diabetic fibrovascular proliferative membranes may minimize postoperative ERM formation and improve visual prognosis.

Particle radiation alters expression of matrix metalloproteases resulting in ECM remodeling in human lens cells.

Relatively low doses of space radiation have been correlated with an increased incidence and earlier appearance of cataracts in space travelers. The lens is a radiosensitive organ of the body with a very obvious late end point of radiation damage--cataract. However, many molecular changes occur in the lens soon after radiation exposure and long before the appearance of an opacification. The goal of our research is to elucidate early mechanisms associated with particle radiation-induced cataractogenesis, with the ultimate goal of developing countermeasures. Normal, cultured non-immortalized human lens cells were grown on matrix-coated plastic tissue culture vessels and irradiated with particle beams at Lawrence Berkeley National Lab (LBNL) or at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Lab. Samples were harvested at different times after radiation exposure. Using a focused genetic approach, total RNA and protein extracts from control and irradiated samples were processed and probed for the expression of genes associated with extracellular matrix (ECM) proteases. Matrix metalloproteinases (MMPs) have previously been studied in adult postmortem human lenses, in post-cataract intraocular lens (IOL) surgery capsular bags and with immortalized human lens cell cultures. Significant differences exist in the expression pattern with these various model systems. We have evidence for the cell stage-specific expression of MMP family of genes during lens fiber differentiation, and for radiation-induced alterations in the misregulation of MMP expression. Our data indicate that radiation exposure may lead to differences in the expression of radiation stress responses, which may impact selective ECM remodeling and cell differentiation.

Evaluation of the impact of shielding materials in radiation protection in transgenic animals.

We are using a plasmid-based transgenic mouse mutation model system to evaluate the effectiveness of aluminum or low-density polyethylene (LDPE) shielding after 250 MeV/u protons or 1 GeV/u iron ion irradiation. Transgenic mice, with multiple copies of the plasmid pUR288 lacZ transgene integrated into the genome of every cell of the animal, were either irradiated or sham-treated. Multiple endpoints, including early cytogenetic damage in erythrocytes at 48 h after exposure, chromosome aberrations in bone marrow lymphocytes, and lacZ mutant frequencies (MF) in brain and spleen tissues were measured in the same animals. The frequency of total circulating reticulocytes (fRET) dropped precipitously at 48 h after 2 Gy of proton irradiation. The average level of micronucleated reticulocytes (fMN-RET) was fivefold higher in the irradiated samples relative to the controls at the same time point. There was an increase in total chromosome aberrations in bone marrow lymphocytes at 8 weeks after proton irradiation but this increase was not statistically significant relative to the controls. Evaluation of the lacZ MF in the brain and spleen tissues showed that proton irradiation induced a twofold increase in MF in each tissue. Similar samples were collected from animals that were shielded from the proton beam by aluminum. Compared to the unshielded treatment group, we noted no difference in fRET, fMN-RET, chromosome aberrations in lymphocytes and lacZ MF in brain and spleen tissues obtained from these animals. In a separate study, animals were exposed to high-energy iron ions with or without 10 or 15 cm LDPE. Using the same approach, we noted a precipitous drop in fRET, and an elevation in fMN-RET within 48 h after 1 Gy of iron ions. Total chromosome aberrations in bone marrow lymphocytes were slightly elevated but not significant at 8 weeks after iron ion exposure. Shielding animals with 10 or 15 cm of polyethylene appeared to have no effect on the level of RET, MN-RET or chromosome aberrations in these animals. LacZ MF in brain and spleen tissues increased 1.5-2-fold above control levels after 1 Gy iron ions at 8 weeks after treatment. On the other hand, MF in tissues harvested from shielded animals appeared to be lower than their unshielded litermates, suggesting the polyethylene shielding was effective in reducing the iron-induced genomic damage in tissues. Although shielding may be effective, in some cases, in reducing the physical dose of particle radiation, our cytogenetic results showed that the biological impact of the particle beam remain unchanged. On the other hand, reduction in transgene MF in tissues from LDPE-shielded animals but not in the aluminum-shielded animals strongly suggests that careful consideration of the biological endpoints used is necessary in the evaluation of the efficacy of the selected shielding material.

MR findings of penile lymphoma.

Penile lymphoma is extremely rare and secondary involvement of the penis by lymphoma may be due to retrograde spread or to direct extension from neighbouring organ. The appearance of penile lymphoma varies and can be mistaken for other soft tissue tumours. We report on a case with malignant lymphoma of the penis. MRI findings revealed soft-tissue mass of homogeneous isointensity around the middle to distal part of penis on T(1) weighted imaging and T(2) weighted imaging. It was well encapsulated, minimally enhanced and distinct from corpus cavernosum and corpus spongiosum.

Effects of iron ions, protons and X rays on human lens cell differentiation.

We have investigated molecular changes in cultured differentiating human lens epithelial cells exposed to high-energy accelerated iron-ion beams as well as to protons and X rays. In this paper, we present results on the effects of radiation on gene families that include or are related to DNA damage, cell cycle regulators, cell adhesion molecules, and cell cytoskeletal function. A limited microarray survey with a panel of cell cycle-regulated genes illustrates that irradiation with protons altered the gene expression pattern of human lens epithelial cells. A focus of our work is CDKN1A (p21(CIP1/WAF1)), a protein that we demonstrate here has a role in several pathways functionally related to LET-responsive radiation damage. We quantitatively assessed RNA and protein expression in a time course before and after single 4-Gy radiation doses and demonstrated that transcription and translation of CDKN1A are both temporally regulated after exposure. Furthermore, we show qualitative differences in the distribution of CDKN1A immunofluorescence signals after exposure to X rays, protons or iron ions, suggesting that LET effects likely play a role in the misregulation of gene function in these cells. A model of molecular and cellular events is proposed to account for precataractous changes in the human lens after exposure to low- or high-LET radiations.

Human Gas7 isoforms homologous to mouse transcripts differentially induce neurite outgrowth.

Gas7, a growth-arrest-specific protein, is expressed preferentially in the brain and is required for neurite outgrowth in cultured cerebellar and peripheral murine neurons. Gas7 interacts with F-actin and colocalizes with the terminal part of actin microfilament in cells in which membrane outgrowth is present. Gas7 isoforms were discovered in murine brain by alternative splicing. This work reports the identification of two human Gas7 cDNA: hGas7-a with 2,427 nucleotides, which encodes 330 amino acids, and hGas7-b with 2,610 nucleotides, which encodes 412 amino acids according to predicted open-reading-frames. The predicted hGas7-b protein is 97% homologous to murine homologues, whereas the hGas7-a is homologous to the mouse Gas7-cb form that is expressed preferentially in cerebellum. Alignment analysis of the Gas7 protein sequences revealed a high homology to that in humans: 99% for the monkey, 97% in murine, and around 75% for the puffer fish and chicken. The hGas7-b protein comprises a WW domain, which often associates with other domains that are typically present in proteins in signal transduction processes, and an FCH domain, which participates in rearranging the cytoskeleton. The hGas7-a comprises only the FCH domain. Analysis of the human Gas7 sequences using the DNA database revealed that the two forms resulted from the canonical alternative splicing of a Gas7 genomic sequence. The abundance of both hGas7 mRNA levels, determined by quantitative PCR in tissues including brain, breast cancer, placenta, and head-neck cancer, revealed that the level of hGas7-a was 14 times that of hGas7-b in these tissues. Transfection of cells with hGas7-a or hGas7-b cDNA yielded the predicted 38-kDa or 50-kDa protein, respectively. The ectopic expression of hGas7 caused neurite-like cell processes in both mouse Neuro-2a and human SH-SY5Y neuroblastoma cells. Interestingly, the hGas7-a preferentially elicited the small lamellipodia, whereas the hGas7-b elicited the small filopodia phenotype. These findings reveal the evolutionary conservation of the structure and function of Gas7. They also suggest that the FCH domain in Gas7 may participate in the development of lamellipodia, and the WW domain may participate in the fine-tuning of the filopodia.

Identification of rat Gas7 isoforms differentially expressed in brain and regulated following kainate-induced neuronal injury.

The growth arrest-specific gene 7 (Gas7) is expressed primarily in the brain and is necessary for the formation of neurite in cultured cerebellar preneurons. The endogenous rat Gas7 (rGas7) is transiently elevated before nerve growth factor-promoted neurite outgrowths emerge in cultured PC12 cells. We report three Gas7 isoforms (a, b, and c) in rat tissues. Peptide microsequencing identified two Gas7 forms, rGas7-a (38 kDa) and rGas7-b (47 kDa). rGas7-c can be predicted from a transcription variant by alternative splicing. Although two open reading frames were predicted, a cloned rGas7 cDNA encoded mostly rGas7-a in mammalian cells. The overexpression of the rGas7 cDNA in PC12 cells sufficed to promote small lamellipodia- and filopodia-like cell processes that resemble the initial stages of neurite formation. Three rGas7 isoforms were differentially expressed in all of the brain subregions. Only rGas7-a was detected in rat cerebellum, as in mouse cerebellum. Kainate injury did not affect the level of rGas7-b, but the level of isoform c was substantially suppressed in the hippocampus. Immunohistochemistry reveals that Gas7 was expressed primarily in the pyramidal neurons of the hippocampus and was quickly attenuated before recovery in the CA3 area after kainate was administered. These results suggest that differential expression and unique regulation of Gas7 isoforms in brain subregions may be important in specialized brain functions. Conservation of Gas7 isoforms by alternative splicing in mammals is also considered.

Synaptotagmin modulation of fusion pore kinetics in regulated exocytosis of dense-core vesicles.

In the exocytosis of neurotransmitter, fusion pore opening represents the first instant of fluid contact between the vesicle lumen and extracellular space. The existence of the fusion pore has been established by electrical measurements, but its molecular composition is unknown. The possibility that synaptotagmin regulates fusion pores was investigated with amperometry to monitor exocytosis of single dense-core vesicles. Overexpression of synaptotagmin I prolonged the time from fusion pore opening to dilation, whereas synaptotagmin IV shortened this time. Both synaptotagmin isoforms reduced norepinephrine flux through open fusion pores. Thus, synaptotagmin interacts with fusion pores, possibly by associating with a core complex of membrane proteins and/or lipid.

Oxidized low-density lipoprotein downregulates endothelial basic fibroblast growth factor through a pertussis toxin-sensitive G-protein pathway: mediator role of platelet-activating factor-like phospholipids.

BACKGROUND: Oxidized LDL (oxLDL) inhibits angiogenesis in part by downregulating endothelial basic fibroblast growth factor (bFGF). To determine the mechanism of the downregulation, we investigated the signal transduction pathway involving potential phospholipid mediators. METHODS AND RESULTS: Cultured bovine aortic endothelial cells were incubated with PBS (lipoprotein-free control), LDL, or copper oxLDL under serum-free conditions. At 24 hours, oxLDL (50 microg/mL) decreased bFGF mRNA (Northern blot), bFGF protein (Western blot and ELISA), and concomitant DNA synthesis, all by 40% to 50% compared with PBS. LDL had no effect. Pretreating the cells with 100 ng/mL pertussis toxin (PTX) for 18 hours before oxLDL exposure almost completely blocked the inhibitory effects of oxLDL. In contrast, inhibiting other major cellular signal transduction pathways with PD-98059 (mitogen-activated protein kinase kinase inhibitor), HA-1004 (inhibitor of cGMP- and cAMP-dependent protein kinase), or Ro-31-8220 (protein kinase C inhibitor) or chelating intracellular Ca(2+) with BAPTA-AM failed to attenuate any of the oxLDL effects assayed. Addition to the cultures of WEB 2086, a specific antagonist of the PTX-sensitive G protein-coupled platelet-activating factor (PAF) receptor, blocked the action of oxLDL. Whereas PAF dispersed in the culture medium failed to produce oxLDL-like effects, degradation of PAF and PAF-like phospholipids accumulated in oxLDL with a recombinant human PAF acetylhydrolase eliminated the inhibitory effects of oxLDL on bFGF expression and DNA synthesis. CONCLUSIONS: OxLDL suppresses endothelial bFGF expression and DNA synthesis through a PTX-sensitive heterotrimeric G-protein pathway involving mediator phospholipids similar, but not identical, to PAF.

Characterization of serum and urinary chromogranin A by size exclusion chromatography: impact on calibrator selection and urinary assay.

Serum chromogranin A (CgA) is a useful marker for neuroendocrine tumors and is detectable in carcinomas at advanced stages. Elevated serum CgA is also an indicator of poor prognosis in prostate cancer and is useful for predicting the failure of hormonal therapy for prostate cancer patients. We found that CgA molecules with three different sizes could be detected in normal human serum. However, only the largest CgA molecule appears in patients with liver disease. Serum taken from cancer patients is composed predominantly of the middle-sized molecule, whereas the smallest CgA molecule was elevated in serum drawn from renal patients. Moreover, only the smallest CgA molecule was found in urine. We believe that the largest CgA molecule is metabolized by the liver, whereas the smallest CgA molecule is removed from the blood circulation via the kidney. Because the medium-sized CgA is the dominant molecule in both the cell medium of the tumor cell line SK-N-AS and sera from patients with malignant diseases, CgA from the cell medium was selected as the calibrator for the CgA ELISA assay. Our findings also suggest that it would not be possible to measure the urinary CgA to reflect the serum CgA concentration in order to detect pheochromocytoma among patients with hypertension.