Patterns of Failure After Prostate-Only Radiotherapy in High-Risk Prostate Cancer: Implications for Refining Pelvic Nodal Contouring Guidelines.

PURPOSE: To study prostate specific membrane antigen - positron emission tomography (Ga68PSMA-PETCT) based patterns of relapse at biochemical failure (BCF) after prostate-only radiotherapy (PORT) in high-risk (HR) prostate cancer and its implications on pelvic contouring recommendations. METHODS AND MATERIALS: Patients with clinico-radiological high-risk node-negative prostate cancer treated with curative PORT and androgen deprivation therapy (ADT), either within the POP-RT randomised trial or off trial, who underwent a Ga68PSMA-PETCT upon BCF were included. Patterns of regional and distant recurrence on Ga68PSMA-PETCT were studied. Pelvic nodal recurrences were mapped with reference to the superior border of pubic symphysis. Pelvic lymph nodal caudal border (PLNcb) recommendations in the published contouring guidelines (RTOGcb, GETUGcb, PIVOTALcb, NRGcb, GFRUcb) were evaluated. RESULTS: Of the total 262 patients screened, 68 eligible patients were included (POP-RT trial 35 patients; off-trial 33 patients). Median follow-up was 91 months (IQR, 72-117) and median time to BCF was 65 months (IQR, 49-83). Regional and distant recurrence was seen in 31 (46%) and 31 (46%) patients, respectively. Of the nodal recurrences, nearly half (46%, 14/31) had no distant metastases and 64% (20/31) had a failure in the common iliac nodal region. The lower-most nodal recurrence was 20 mm cranial to the top of pubic symphysis (RTOGcb, GETUGcb, GFRUcb) and 10 mm cranial to the PIVOTALcb. The PLNcb recommended by NRG guideline (NRGcb) had an inter-patient variability of 32 mm, ranging from 16 mm above to 16 mm below the top of pubic symphysis, and the lower most nodal recurrence ranged from 4 mm to 36 mm cranial to NRGcb. CONCLUSION: Pelvic failures accounted for a major proportion of recurrences after prostate-only radiotherapy, with the caudal most nodal recurrence being 20 mm cranial to the top of pubic symphysis. This could have implications in defining the caudal border of contouring recommendations.

Internal evaluation of risk stratification tool using serial procalcitonin and clinical risk factors in pediatric febrile neutropenia: The non-interventional, single institution experience prior to clinical implementation.

Risk stratification of pediatric febrile neutropenia (FN) is an established concept, yet clinical risk tools misclassify nearly 5% of clinical standard-risk episodes with severe outcomes. The internal evaluation of a clinical risk tool before implementation has not been well-described. In this noninterventional cohort study, we evaluated a study decision rules (SDR) tool; a clinical risk tool with serial procalcitonin. The study standard-risk (SSR) group met clinical standard-risk criteria with two serial procalcitonin <0.4 ng/mL. The study high-risk (SHR) group met clinical high-risk criteria or clinical standard-risk with a procalcitonin ≥0.4 ng/mL. Descriptive and bivariate statistics compared the groups and outcomes. Clinical criteria alone identified 39.1% (238/608) standard-risk episodes; 5.9% (14/238) had severe events. Prospectively using the SDR, the SHR group encompassed 76.6% (92/120) of episodes; severe events occurred in 20% (3/15) of standard-risk episodes included due to elevated procalcitonin ≥0.4 ng/mL. The SHR group had more blood stream infections [21.7% (20/92) vs. 0% (0/28); P = 0.007] and intensive care admissions [13% (12/92) vs. 3.6% (1/28); P = 0.158]. In conclusion, the SDR with serial procalcitonin aided in identifying severe events in clinical standard-risk episodes, but analysis was limited. Institutions may consider similar internal evaluation methodology before FN episode risk stratification.

Effects of vedolizumab on health-related quality of life in patients with ulcerative colitis: results from the randomised GEMINI 1 trial.

BACKGROUND: Health-related quality of life (HRQL) is often diminished in patients with ulcerative colitis. AIM: To evaluate the effects of vedolizumab on HRQL in patients with ulcerative colitis. METHODS: Using maintenance phase data from the GEMINI 1 study, an analysis of covariance model was used to calculate mean differences between the vedolizumab and placebo groups in changes from baseline to week 52 for 3 HRQL instruments: The Inflammatory Bowel Disease Questionnaire (IBDQ), 36-Item Short Form Health Survey (SF-36), and EQ-5D. Proportions of patients meeting minimal clinically important difference (MCID) thresholds for changes on these instruments were compared between treatment groups for the overall population and for clinically important subgroups. Concordance between clinical remission and remission defined using IBDQ scores was examined. RESULTS: Compared with placebo-treated patients, vedolizumab-treated patients had greater improvements (152-201%) in IBDQ, EQ-5D visual analogue scale (VAS), and EQ-5D utility scores. Greater proportions (6.9-19.9%) of vedolizumab-treated patients than placebo-treated patients met MCID thresholds for all the instruments. Vedolizumab-treated patients with lower baseline disease activity and those without prior tumour necrosis factor (TNF) antagonist failure had greater HRQL improvements. Among 127 patients with clinical remission based on complete Mayo Clinic scores, >80% also had IBDQ remission; >70% of the 150 patients with IBDQ remission demonstrated clinical remission. CONCLUSIONS: Vedolizumab therapy was associated with significant improvements in HRQL measures compared with placebo. Benefits were greater in patients with lower disease activity and no prior TNF antagonist failure.

Use of Whole Genome Sequencing and Patient Interviews To Link a Case of Sporadic Listeriosis to Consumption of Prepackaged Lettuce.

We report on a case of listeriosis in a patient who probably consumed a prepackaged romaine lettuce-containing product recalled for Listeria monocytogenes contamination. Although definitive epidemiological information demonstrating exposure to the specific recalled product was lacking, the patient reported consumption of a prepackaged romaine lettuce-containing product of either the recalled brand or a different brand. A multinational investigation found that patient and food isolates from the recalled product were indistinguishable by pulsed-field gel electrophoresis and were highly related by whole genome sequencing, differing by four alleles by whole genome multilocus sequence typing and by five high-quality single nucleotide polymorphisms, suggesting a common source. To our knowledge, this is the first time prepackaged lettuce has been identified as a likely source for listeriosis. This investigation highlights the power of whole genome sequencing, as well as the continued need for timely and thorough epidemiological exposure data to identify sources of foodborne infections.

Risk of developing colorectal cancer and benign colorectal neoplasm in patients with chronic constipation.

BACKGROUND: Chronic constipation (CC) is a highly prevalent health problem, potentially associated with increased risk of colorectal cancer (CRCancer). AIM: To investigate the association between CC, its severity, and CRCancer by estimating the relative risk of developing CRCancer and benign colorectal neoplasm (BCN) among severity-stratified patients with and without CC. METHODS: Chronic constipation patients from a large retrospective US claims database were matched 1:3 with CC-free controls by demographic characteristics. CRCancer and BCN prevalence were measured over 1 year. In pre-index CRCancer- and BCN-free patients, incidence rate ratios (IRRs) of new CRCancer and BCN were calculated. Multivariate regression models adjusted for comorbidities and family history. CC patients' disease severity was rated based on CC-related resource use. IRRs for new CRCancer and BCN were estimated for CC severity groups and controls. RESULTS: Chronic constipation (N = 28,854) and CC-free (N = 86,562) patients had mean age 61.9 years; 66.7% were female. One-year CRCancer prevalence was 2.7% and 1.7%, and BCN prevalence was 24.8% and 11.9% for CC and CC-free patients, respectively. Adjusted IRRs between CC and CC-free patients were 1.59 [95% confidence interval (CI): 1.43-1.78] and 2.60 [95% CI: 1.51-2.70] for CRCancer and BCN, respectively. Patients with severe and very severe CC had significantly greater incidence of CRCancer and BCN. At ≥ 2 and ≥ 5 years of observation, CRCancer and BCN incidence remained consistently and significantly higher for CC patients. CONCLUSIONS: Patients with chronic constipation are associated with significantly higher prevalence and incidence of colorectal cancer and benign colorectal neoplasm than matched chronic constipation-free patients. These risks increase with the severity of chronic constipation.

Real-world assessment of therapy changes, suboptimal treatment and associated costs in patients with ulcerative colitis or Crohn's disease.

BACKGROUND: Treatments for Crohn's disease (CD) and ulcerative colitis (UC) are not uniformly effective, thus necessitating dose changes, switching, and augmentation and carry adverse event risk, often requiring discontinuation, which reduces treatment benefits. AIM: To assess continuity of and changes to initial CD and UC treatments, as well as costs associated with specific parameters defining suboptimal therapy. METHODS: Commercial US insurance claims (2006-2010) were retrospectively analysed. CD and UC patients receiving monotherapy with 5-aminosalicylates (5-ASAs), corticosteroids (CS), immunomodulators (IM) or biologics were included. Continuity of and changes to initial (index) therapy and associated costs (2011 US$) were assessed over 12 months following therapy initiation. Suboptimal therapy included discontinuation or switch (except for CS), dose escalation, augmentation, inadequate loading (biologics only), prolonged CS use (>3 months), surgery or hospitalisation. RESULTS: The study included 13,005 CD and 19,878 UC patients. Augmentation was a common index therapy change (~20% of 5-ASA initiators, ~40% of CS initiators, ≥40% of IM initiators and 26-55% of biologic initiators) in both CD and UC patients. Approximately 50% of CD and UC 5-ASA initiators discontinued/interrupted treatment. Approximately 80% of CD and UC patients had ≥1 suboptimal therapy marker. Mean all-cause total costs per CD patient were significantly higher in those with vs. without suboptimal therapy ($18,736 vs. $10,878; P < 0.001); in UC, the disparity was smaller ($12,679 vs. $9653; P < 0.001). CONCLUSIONS: Frequent dose and treatment changes were observed in all classes of initial UC and CD treatments. The economic impact of suboptimal therapy among UC and CD patients is substantial.

Multiple-aetiology enteric infections involving non-O157 Shiga toxin-producing Escherichia coli--FoodNet, 2001-2010.

We describe multiple-aetiology infections involving non-O157 Shiga toxin-producing Escherichia coli (STEC) identified through laboratory-based surveillance in nine FoodNet sites from 2001 to 2010. A multiple-aetiology infection (MEI) was defined as isolation of non-O157 STEC and laboratory evidence of any of the other nine pathogens under surveillance or isolation of >1 non-O157 STEC serogroup from the same person within a 7-day period. We compared exposures of patients with MEI during 2001-2010 with those of patients with single-aetiology non-O157 STEC infections (SEI) during 2008-2009 and with those of the FoodNet population from a survey conducted during 2006-2007. In total, 1870 non-O157 STEC infections were reported; 68 (3.6%) were MEI; 60 included pathogens other than non-O157 STEC; and eight involved >1 serogroup of non-O157 STEC. Of the 68 MEI, 21 (31%) were part of six outbreaks. STEC O111 was isolated in 44% of all MEI. Of patients with MEI, 50% had contact with farm animals compared with 29% (P < 0.01) of persons with SEI; this difference was driven by infections involving STEC O111. More patients with non-outbreak-associated MEI reported drinking well water (62%) than respondents in a population survey (19%) (P < 0.01). Drinking well water and having contact with animals may be important exposures for MEI, especially those involving STEC O111.

Outbreaks of non-O157 Shiga toxin-producing Escherichia coli infection: USA.

Non-O157 Shiga toxin-producing Escherichia coli (STEC) infections are increasingly detected, but sources are not well established. We summarize outbreaks to 2010 in the USA. Single-aetiology outbreaks were defined as ⩾2 epidemiologically linked culture-confirmed non-O157 STEC infections; multiple-aetiology outbreaks also had laboratory evidence of ⩾2 infections caused by another enteric pathogen. Twenty-six states reported 46 outbreaks with 1727 illnesses and 144 hospitalizations. Of 38 single-aetiology outbreaks, 66% were caused by STEC O111 (n = 14) or O26 (n = 11), and 84% were transmitted through food (n = 17) or person-to-person spread (n = 15); food vehicles included dairy products, produce, and meats; childcare centres were the most common setting for person-to-person spread. Of single-aetiology outbreaks, a greater percentage of persons infected by Shiga toxin 2-positive strains had haemolytic uraemic syndrome compared with persons infected by Shiga toxin 1-only positive strains (7% vs. 0·8%). Compared with single-aetiology outbreaks, multiple-aetiology outbreaks were more frequently transmitted through water or animal contact.

Outbreak of Salmonella enterica serotype I 4,5,12:i:- infections: the challenges of hypothesis generation and microwave cooking.

We investigated an outbreak of 396 Salmonella enterica serotype I 4,5,12:i:- infections to determine the source. After 7 weeks of extensive hypothesis-generation interviews, no refined hypothesis was formed. Nevertheless, a case-control study was initiated. Subsequently, an iterative hypothesis-generation approach used by a single interviewing team identified brand A not-ready-to-eat frozen pot pies as a likely vehicle. The case-control study, modified to assess this new hypothesis, along with product testing indicated that the turkey variety of pot pies was responsible. Review of product labels identified inconsistent language regarding preparation, and the cooking instructions included undefined microwave wattage categories. Surveys found that most patients did not follow the product's cooking instructions and did not know their oven's wattage. The manufacturer voluntarily recalled pot pies and improved the product's cooking instructions. This investigation highlights the value of careful hypothesis-generation and the risks posed by frozen not-ready-to-eat microwavable foods.

Distinguishing the impact of dexlansoprazole on heartburn vs. regurgitation in patients with gastro-oesophageal reflux disease.

BACKGROUND: Gastro-oesophageal reflux disease (GERD) is characterised by symptomatic heartburn and regurgitation. Treatment with proton pump inhibitors (PPI) effectively decreases heartburn symptoms, but their effects on symptomatic regurgitation are less clear. AIM: To determine the impact of PPI therapy on heartburn and regurgitation severity in patients with either non-erosive GERD (NERD) or erosive oesophagitis (EE). METHODS: Endoscopically-confirmed NERD patients received dexlansoprazole 30 or 60 mg or placebo in a randomised, blinded, 4-week study. Endoscopically-confirmed EE patients received dexlansoprazole 60 mg or lansoprazole 30 mg in two 8-week, randomised, blinded healing studies. The Patient Assessment of Upper Gastrointestinal Symptom Severity questionnaire, which includes a heartburn/regurgitation subscale, was administered to assess symptom severity at baseline, and at weeks 2 and 4 of the NERD study and at weeks 4 and 8 during the EE trials. We defined separate subscales for heartburn and regurgitation for this post-hoc analysis. Among patients with both symptoms at baseline, improvements in individual heartburn and regurgitation subscales along with the original combined heartburn/regurgitation subscale were determined. RESULTS: In the NERD and EE studies, 661 and 1909 patients, respectively, had both heartburn and regurgitation at baseline. NERD patients receiving dexlansoprazole 30 and 60 mg experienced significantly greater improvements in symptom severity for both heartburn and regurgitation compared with placebo. EE patients receiving dexlansoprazole 60 mg had significantly greater improvements in heartburn/regurgitation and heartburn-only subscales at week 4 compared with those receiving lansoprazole. CONCLUSIONS: Dexlansoprazole appears to be effective in improving both heartburn and regurgitation, and this improvement is maintained for the duration of treatment.

The effects of increasing body mass index on heartburn severity, frequency and response to treatment with dexlansoprazole or lansoprazole.

BACKGROUND: Higher body mass index (BMI) is a recognised risk factor for gastro-oesophageal reflux disease (GERD). Data regarding the impact of BMI on proton pump inhibitor (PPI) therapy are conflicting. AIM: To assess the impact of BMI on baseline heartburn symptom severity and frequency and response to PPI therapy in patients with non-erosive GERD (NERD) or erosive oesophagitis (EO). METHODS: In post hoc analyses of phase 3 trial data, 621 NERD and 2692 EO patients were stratified by BMI (<25, 25 to <30 and ≥30 kg/m(2) ). NERD patients received either dexlansoprazole MR 30 mg or placebo daily for 4 weeks. EO patients received either dexlansoprazole MR 60 mg or lansoprazole 30 mg for 8 weeks. Symptom frequency and severity were assessed at baseline and subsequently by daily diary. RESULTS: In both the NERD and EO cohorts, baseline heartburn severity increased with increasing BMI. The impact of PPI therapy on the reduction in heartburn symptom frequency and severity in both NERD and EO patients was similar across BMI categories. EO healing rates in patients treated with dexlansoprazole but not lansoprazole were higher in obese patients compared with those with a BMI <30 kg/m(2) . Differences between the PPIs were small. CONCLUSIONS: The PPIs evaluated in this study reduced the frequency and severity of 24-h heartburn regardless of baseline BMI. In addition, because patients with higher BMI have more severe symptoms at baseline, they may experience greater therapeutic gain with dexlansoprazole (NERD and erosive oesophagitis) and possibly lansoprazole (erosive oesophagitis) treatment.

Real-time modelling used for outbreak management during a cholera epidemic, Haiti, 2010-2011.

The emergence of epidemic cholera in post-earthquake Haiti portended a public health disaster of uncertain magnitude. In order to coordinate relief efforts in an environment with limited healthcare infrastructure and stretched resources, timely and realistic projections of the extent of the cholera outbreak were crucial. Projections were shared with Government and partner organizations beginning 5 days after the first reported case and were updated using progressively more advanced methods as more surveillance data became available. The first projection estimated that 105 000 cholera cases would occur in the first year. Subsequent projections using different methods estimated up to 652 000 cases and 163 000-247 000 hospitalizations during the first year. Current surveillance data show these projections to have provided reasonable approximations of the observed epidemic. Providing the real-time projections allowed Haitian ministries and external aid organizations to better plan and implement response measures during the evolving epidemic.

Serum circulating immune complexes as prognostic indicators in premalignant and malignant lesions of oral cavity during and following radiotherapy.

AIM: The aim of the study has been to quantitatively estimate and compare the circulating immune complexes (CIC) in pre-malignant and malignant lesions of oral cavity and to serially monitor the CIC levels in oral squamous cell carcinoma (SCC) during / following radiotherapy as to assess the status of the disease and to understand the prognostic significance. MATERIALS AND METHODS: The present study was carried out on 90 individuals divided into three groups and CIC was estimated by spectrophotometric method using polyethylene glycol (PEG) precipitation method. The mean CIC level was determined in each group and was correlated with the degree of differentiation and degree of dysplasia in malignant and pre-malignant group respectively. The effect of radiotherapy on the level of CIC was studied after 2400 rad and after one week of 4500 - 5000 rad. RESULTS: It was observed that the mean CIC level in the control group was significantly lower (59.56 ± 8.11) when compared with the pre-malignant group (75.93 ± 12.89) and malignant group (92.66 ± 13.96). Among the pre-malignant group, leukoplakia had the highest mean CIC level followed by lichen planus and oral submucous fibrosis (OSMF), suggesting its greater malignant potential. No correlation could be established between degree of differentiation and degree of dysplasia with the CIC levels in malignant and premalignant groups respectively. There was a definite decrease in the mean CIC levels in patients undergoing radiotherapy. CONCLUSION: The pretreatment value of CIC can be used as a prognostic indicator. A high CIC level would probably indicate a poor prognosis.

Epidemiology of a large restaurant-associated outbreak of Shiga toxin-producing Escherichia coli O111:NM.

In August 2008, a large outbreak of Shiga toxin-producing Escherichia coli (STEC) O111:NM infections associated with a buffet-style restaurant in rural Oklahoma was identified. A case-control study of restaurant patrons and a retrospective cohort study of catered event attendees were conducted coupled with an environmental investigation to determine the outbreak's source and mode of transmission. Of 1823 persons interviewed, 341 (18·7%) met the outbreak case definition; 70 (20·5%) were hospitalized, 25 (7·3%) developed haemolytic uraemic syndrome, and one died. Multiple food items were significantly associated with illness by both bivariate and multivariate analyses, but none stood out as a predominant transmission vehicle. All water, food, and restaurant surface swabs, and stool cultures from nine ill employees were negative for the presence of Shiga toxin and E. coli O111:NM although epidemiological evidence suggested the outbreak resulted from cross-contamination of restaurant food from food preparation equipment or surfaces, or from an unidentified infected food handler.

Prevalence and relationship of human papilloma virus type 16 and type 18 with oral squamous cell carcinoma and oral leukoplakia in fresh scrappings: a PCR study.

INTRODUCTION: It has been always an area of diffuse clarity when you study malignancy and its pathogenesis. Recently, it has invited lot of interest among the researchers about the possibility of role of viruses in the initiation of carcinogenesis. Recent advances in the field of molecular biology and biotechnology have solved some problems with regard to pathogenesis. Human papilloma virus (HPV) and its role in the initiation of malignancy in the cervix is proven almost beyond doubt. OBJECTIVES: The present study is aimed at the role of two types of HPV 16 and 18 in the initiation of oral premalignant and squamous cell carcinoma. The study also aims at using polymerase chain reaction (PCR) in finding out the prevalence of these types diagnosed histologically as oral leukoplakia and oral squamous cell carcinoma and prevalence of its association with the habit of tobacco use. MATERIALS AND METHODS: In the present study, 45 patients having histopathologically confirmed oral squamous cell carcinoma in the age range of 32-85 years were selected along with 20 histopathologically confirmed oral leukoplakia in the age range 22-66 years. All the samples were subjected to polymerase chain reaction. The PCR reaction was carried out in PTC 200 thermo-cycler [MJ Research Inc, Watertown, MA, USA]. RESULTS: The site prevalence and co-infection rate of these two types of viruses are being analyzed using very simple non-invasive scrapings obtained from fresh scrapings and found to be really high. It was also observed that 73.3% (33/45) of the oral squamous cell carcinoma patients were positive for oral HPV type 16 while 71.1% (32/45) were positive for HPV type 18 infection and 57.7% (26/45) were found to have both HPV type 16 and HPV type 18 infections. CONCLUSIONS: HPV type 16, 18, and co-infection of both types showed high prevalence in oral squamous cell carcinoma.The prevalence of HPV type 18 was found to be higher than HPV type 16 and co-infection in oral leukoplakia. It was observed that the tongue and palate lesions in the oral squamous cell carcinoma patients showed high prevalence of HPV type 16, type 18, and co-infection compared with other sites.

The development and validation of a Nocturnal Gastro-oesophageal Reflux Disease Symptom Severity and Impact Questionnaire for adults.

BACKGROUND: Current questionnaires for assessing gastro-oesophageal reflux disease (GERD) symptoms are limited in their ability to capture nocturnal symptoms. AIM: To develop and validate an instrument, the Nocturnal Gastro-oesophageal Reflux Disease Symptom Severity and Impact Questionnaire (N-GSSIQ), to assess severity and impact of nocturnal GERD symptoms. METHODS: Two focus groups and 16 cognitive debriefing interviews were conducted among GERD patients to identify key issues about nocturnal symptoms. A draft instrument was tested in 196 patients at 11 clinics in the US to evaluate psychometric properties. Exploratory factor and item response theory analyses were conducted to finalize items and subscales. Internal consistency reliability, reproducibility and construct validity were examined. RESULTS: Mean age was 45 (s.d. = 13.8) years; 76% were female and 68% were Caucasian. Patient-rated severity was mild-moderate for 69% of participants; 48% reported symptoms on two to three nights the past week. The final questionnaire includes 20 items and three subscales: Nocturnal GERD Symptoms, Morning Impact of Nocturnal GERD and Concern about Nocturnal GERD. The subscales demonstrated internal consistency reliability (Cronbach's alpha 0.84-0.94) and were significantly correlated with similar measures and disease severity (0.41-0.81; P < 0.0001). CONCLUSION: The results support the reliability and validity of the N-GSSIQ as a measure of severity, morning impact and concern about nocturnal GERD.

Rituximab (Rituxan).

Rituximab is a monoclonal antibody that was first approved by the FDA as an antineoplastic agent designed to treat B-cell malignancies. This article will review the mechanism of action and clinical role of this anti-B-cell agent.

Estimation of serum leptin in oral squamous cell carcinoma.

BACKGROUND: Cachexia contributes significantly to mortality in cancer patients; role of cytokines in inducing cachexia is an emerging view. Leptin, a homologous protein of cytokine family, is found to be decreased in serum with cachexia. The purpose of this study was to compare serum leptin levels of oral squamous cell carcinoma patients with that of control group and correlate it with body mass index. METHOD: Serum samples of 31 oral squamous cell carcinoma patients and that of 28 healthy individuals were subjected to evaluation of serum leptin levels (ng/ml) using enzyme-linked immunosorbent assay. RESULTS: A significant reduction in leptin level of oral squamous cell carcinoma patients was observed. Definite correlation between body mass index and serum leptin and also between serum leptin levels of various histopathological variants of oral squamous cell carcinoma was observed. CONCLUSION: The results of this study suggest that evaluation of serum leptin level can provide status of cachexia in oral squamous cell carcinoma patients.

Localization of a human reduced folate carrier protein in the mitochondrial as well as the cell membrane of leukemia cells.

IgG polyclonal antiserum was generated in New Zealand White rabbits immunized with a 16-mer peptide consisting of a specific amino acid sequence at residues corresponding to the sixth to seventh predicted transmembrane domain of the human reduced folate carrier (RFC). Using Western immunoblotting to examine the cytosolic and membrane fractions of the human CCRF-CEM T-cell lymphoblastic leukemia cell line, polyclonal antihuman RFC antiserum recognized two bands in the cytosolic fraction (approximately 60 kDa and approximately 70 kDa) on 10% polyacrylamide gels. In the membrane fraction, an approximately 60-kDa protein was identified. Comparative studies of a panel of human tumor cell lines including the HT1080 fibrosarcoma, 8805 malignant fibrous histiocytoma, and the MCF breast cancer cell lines revealed similar findings. Likewise, a recombinant approximately 60-kDa membrane protein was identified after expression of baculovirus-infected Sf9 insect cells containing cDNA of the human RFC. In the CEM-7A cell line, a variant of the CCRF-CEM cell line that overexpresses the RFC, 21-fold overexpression of the approximately 60-kDa membrane protein (RFC) was shown by Western analysis. To characterize further the cellular distribution of the human RFC, immunohistochemical analyses were performed in CCRF-CEM T-cell lymphoblastic leukemia cells. Predominantly membrane localization of the antibody reacting sites was detected; however, a cytoplasmic component was noted as well. By confocal microscopy and by immunogold electron microscopy, the cytoplasmic expression was found to be largely of mitochondrial origin. These findings were corroborated by Western immunoblotting of mitochondrial membrane isolates from the CCRF-CEM cell line, which demonstrate an approximately 60-kDa protein. The localization of the human RFC to the mitochondrial membrane is a novel finding, and it suggests a role for the mitochondrial membrane in the transport of folates.