Hyperpolarized [1-13C]Pyruvate Magnetic Resonance Spectroscopic Imaging for Evaluation of Early Response to Tyrosine Kinase Inhibition Therapy in Gastric Cancer

PURPOSE

To evaluate the use of hyperpolarized [1-13C]pyruvate magnetic resonance spectroscopic imaging (HP-13C MRSI) for quantitative measurement of early changes in glycolytic metabolism and its ability to predict response to pan-tyrosine kinase inhibitor (Pan-TKI) therapy in gastric cancer (GCa).

PROCEDURES

Pan-TKI afatinib-sensitive NCI-N87 and resistant SNU16 human GCa cells were assessed for GLUT1, hexokinase-II (HKII), lactate dehydrogenase (LDHA), phosphorylated AKT (pAKT), and phosphorylated MAPK (pMAPK) at 0-72 h of treatment with 0.1 μM afatinib. Subcutaneous NCI-N87 tumor-bearing nude mice underwent [18F]FDG PET/MRI and HP-13C MRSI at baseline and 4 days after treatment with afatinib 10 mg/kg/day or vehicle (n = 10/group). Changes in PET and HP-13C MRSI metabolic parameters were compared between the two groups. Imaging findings were correlated with tumor growth and histopathology over 3 weeks of treatment.

RESULTS

In vitro analysis showed a continuous decrease in LDHA, pAKT, and pMAPK in NCI-N87 compared to SNU16 cells within 72 h of treatment with afatinib, without a significant change in GLUT1 and HKII in either cell type. [18F]FDG PET of NCI-N87 tumors showed no significant change in PET measures at baseline and day 4 of treatment in either treatment group (SUVmean day 4/day 0: 2.7 ± 0.42/2.34 ± 0.38, p = 0.57 in the treated group vs. 1.73 ± 0.66/2.24 ± 0.43, p = 0.4 in the control group). HP-13C MRSI demonstrated significantly decreased lactate-to-pyruvate ratio (L/P) in treated tumors (L/P day 4/day 0: 0.83 ± 0.30/1.10 ± 0.20, p = 0.012 vs. 0.94 ± 0.20/0.98 ± 0.30, p = 0.75, in the treated vs. control group, respectively). Response to afatinib was confirmed with decreased tumor size over 3 weeks (11.10 ± 16.50 vs. 293.00 ± 79.30 mm3, p < 0.001, treated group vs. control group, respectively) and histopathologic evaluation.

CONCLUSIONS

HP-13C MRSI is a more representative biomarker of early metabolic changes in response to pan-TKI in GCa than [18F]FDG PET and could be used for early prediction of response to targeted therapies.

PFKFB3-mediated Pro-glycolytic Shift in Hepatocellular Carcinoma Proliferation

BACKGROUND & AIMS

Metabolic reprogramming, in particular, glycolytic regulation, supports abnormal survival and growth of hepatocellular carcinoma (HCC) and could serve as a therapeutic target. In this study, we sought to identify glycolytic regulators in HCC that could be inhibited to prevent tumor progression and could also be monitored in vivo, with the goal of providing a theragnostic alternative to existing therapies.

METHODS

An orthotopic HCC rat model was used. Tumors were stimulated into a high-proliferation state by use of off-target liver ablation and were compared with lower-proliferating controls. We measured in vivo metabolic alteration in tumors before and after stimulation, and between stimulated tumors and control tumors using hyperpolarized 13C magnetic resonance imaging (MRI) (h13C MRI). We compared metabolic alterations detected by h13C MRI to metabolite levels from ex vivo mass spectrometry, mRNA levels of key glycolytic regulators, and histopathology.

RESULTS

Glycolytic lactate flux increased within HCC tumors 3 days after tumor stimulation, correlating positively with tumor proliferation as measured with Ki67. This was associated with a shift towards aerobic glycolysis and downregulation of the pentose phosphate pathway detected by mass spectrometry. MRI-measured lactate flux was most closely coupled with PFKFB3 expression and was suppressed with direct inhibition using PFK15.

CONCLUSIONS

Inhibition of PFKFB3 prevents glycolytic-mediated HCC proliferation, trackable by in vivo h13C MRI.

The Limit of Detection Matters: The Case for Benchmarking Severe Acute Respiratory Syndrome Coronavirus 2 Testing

BACKGROUND

Resolving the coronavirus disease 2019 (COVID-19) pandemic requires diagnostic testing to determine which individuals are infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The current gold standard is to perform reverse-transcription polymerase chain reaction (PCR) on nasopharyngeal samples. Best-in-class assays demonstrate a limit of detection (LoD) of approximately 100 copies of viral RNA per milliliter of transport media. However, LoDs of currently approved assays vary over 10,000-fold. Assays with higher LoDs will miss infected patients. However, the relative clinical sensitivity of these assays remains unknown.

METHODS

Here we model the clinical sensitivities of assays based on their LoD. Cycle threshold (Ct) values were obtained from 4700 first-time positive patients using the Abbott RealTime SARS-CoV-2 Emergency Use Authorization test. We derived viral loads from Ct based on PCR principles and empiric analysis. A sliding scale relationship for predicting clinical sensitivity was developed from analysis of viral load distribution relative to assay LoD.

RESULTS

Ct values were reliably repeatable over short time testing windows, providing support for use as a tool to estimate viral load. Viral load was found to be relatively evenly distributed across log10 bins of incremental viral load. Based on these data, each 10-fold increase in LoD is expected to lower assay sensitivity by approximately 13%.

CONCLUSIONS

The assay LoD meaningfully impacts clinical performance of SARS-CoV-2 tests. The highest LoDs on the market will miss a majority of infected patients. Assays should therefore be benchmarked against a universal standard to allow cross-comparison of SARS-CoV-2 detection methods.

Saliva is Comparable to Nasopharyngeal Swabs for Molecular Detection of SARS-CoV-2

The continued need for molecular testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the potential for self-collected saliva as an alternative to nasopharyngeal (NP) swabs for sample acquisition led us to compare saliva to NP swabs in an outpatient setting without restrictions to avoid food, drink, smoking, or tooth-brushing. A total of 385 pairs of NP and saliva specimens were obtained, the majority from individuals presenting for initial evaluation, and were tested on two high-sensitivity reverse transcriptase PCR (RT-PCR) platforms, the Abbott m2000 and Abbott Alinity m (both with limits of detection [LoD] of 100 copies of viral RNA/ml). Concordance between saliva and NP swabs was excellent overall (Cohen's κ = 0.93) for both initial and follow-up testing, for both platforms, and for specimens treated with guanidinium transport medium as preservative as well as for untreated saliva (κ = 0.88 to 0.95). Viral loads were on average 16× higher in NP specimens than saliva specimens, suggesting that only the relatively small fraction of outpatients (∼8% in this study) who present with very low viral loads (<1,600 copies/ml from NP swabs) would be missed by testing saliva instead of NP swabs when using sensitive testing platforms. Special attention was necessary to ensure leak-resistant specimen collection and transport. The advantages of self-collection of saliva, without behavioral restrictions, will likely outweigh a minor potential decrease in clinical sensitivity in individuals less likely to pose an infectious risk to others for many real-world scenarios, especially for initial testing. IMPORTANCE In general, the most accurate COVID-19 testing is hands-on and uncomfortable, requiring trained staff and a "brain-tickling" nasopharyngeal swab. Saliva would be much easier on both fronts, since patients could collect it themselves, and it is after all just spit. However, despite much interest, it remains unclear how well saliva performs in real-world settings when just using it in place of an NP swab without elaborate or cumbersome restrictions about not eating/drinking before testing, etc. Also, almost all studies of COVID-19 testing, whether of NP swabs, saliva, or otherwise, have been restricted to reporting results in the abstruse units of "CT values," which only mean something in the context of a specific assay and testing platform. Here, we compared saliva versus NP swabs in a real-world setting without restriction and report all results in natural units-the amount of virus being shed-showing that saliva is essentially just as good as NP swabs.

Nasal Swab Performance by Collection Timing, Procedure, and Method of Transport for Patients with SARS-CoV-2

The urgent need for large-scale diagnostic testing for SARS-CoV-2 has prompted interest in sample collection methods of sufficient sensitivity to replace nasopharynx (NP) sampling. Nasal swab samples are an attractive alternative; however, previous studies have disagreed over how nasal sampling performs relative to NP sampling. Here, we compared nasal versus NP specimens collected by health care workers in a cohort of individuals clinically suspected of COVID-19 as well as SARS-CoV-2 reverse transcription (RT)-PCR-positive outpatients undergoing follow-up. We compared subjects being seen for initial evaluation versus follow-up, two different nasal swab collection protocols, and three different transport conditions, including traditional viral transport media (VTM) and dry swabs, on 307 total study participants. We compared categorical results and viral loads to those from standard NP swabs collected at the same time from the same patients. All testing was performed by RT-PCR on the Abbott SARS-CoV-2 RealTime emergency use authorization (EUA) (limit of detection [LoD], 100 copies viral genomic RNA/ml transport medium). We found low concordance overall, with Cohen's kappa (κ) of 0.49, with high concordance only for subjects with very high viral loads. We found medium concordance for testing at initial presentation (κ = 0.68) and very low concordance for follow-up testing (κ = 0.27). Finally, we show that previous reports of high concordance may have resulted from measurement using assays with sensitivity of ≥1,000 copies/ml. These findings suggest nasal-swab testing be used for situations in which viral load is expected to be high, as we demonstrate that nasal swab testing is likely to miss patients with low viral loads.

Visualizing the effects of lactate dehydrogenase (LDH) inhibition and LDH-A genetic ablation in breast and lung cancer with hyperpolarized pyruvate NMR

In many tumors, cancer cells take up large quantities of glucose and metabolize it into lactate, even in the presence of sufficient oxygen to support oxidative metabolism. It has been hypothesized that this malignant metabolic phenotype supports cancer growth and metastasis, and that reversal of this so-called "Warburg effect" may selectively harm cancer cells. Conversion of glucose to lactate can be reduced by ablation or inhibition of lactate dehydrogenase (LDH), the enzyme responsible for conversion of pyruvate to lactate at the endpoint of glycolysis. Recently developed inhibitors of LDH provide new opportunities to investigate the role of this metabolic pathway in cancer. Here we show that magnetic resonance spectroscopic imaging of hyperpolarized pyruvate and its metabolites in models of breast and lung cancer reveal that inhibition of LDH was readily visualized through reduction in label exchange between pyruvate and lactate, while genetic ablation of the LDH-A isoform alone had smaller effects. During the acute phase of LDH inhibition in breast cancer, no discernible bicarbonate signal was observed and small signals from alanine were unchanged.

Abstract 2807: Variations in glycolytic activity of HCC subtypes as monitored by in vivo h 13C MRI

Hepatocellular carcinoma (HCC) is the 4th leading cause of cancer-related death worldwide. Despite therapeutic advancements, a significant proportion of patients progress, highlighting the need to improve diagnostic approaches to monitor therapy. Radiofrequency ablation (RFA), an accepted locoregional therapy for early HCC, can stimulate more aggressive tumor biology within under-treated or distant tumors. Increased glycolytic activity is a hallmark feature of cancer, but variations in metabolism and its link to tumor aggression can impact the sensitivity of HCC to therapies affecting these pathways. Tumor metabolic phenotypes can be characterized by hyperpolarized 13C MRI (h13C MRI), which can also be used to assess treatment response. In this study, we used orthotopic rat HCC models with two different cell lines N1S1 and MCA-RH7777, and analyzed their mRNA expression of glycolysis-related genes and in vivo glycolytic activity with h13C MRI. We then partially-treated tumors with radiofrequency ablation (RFA) and used h13C MRI to measure in vivo tumor metabolism before and 3 days after RFA to compare them to histologic and phenotypical measures of disease progression.

N1S1 tumors grew only as single lesions, while MCA-RH7777 rapidly produced intra-hepatic and distal metastases. Glycolysis-related genes including HK2, HK3, PFKFB3, and MCT4 were highly expressed in N1S1, but not in MCA-RH7777, while GPT1 was highly expressed in MCA-RH7777 but not in N1S1. In vivo h13C MRI demonstrated significantly increased 13C lactate flux in N1S1 tumor compared to the background normal liver, while 13C lactate flux in MCA-RH7777 rat model did not, consistent with mRNA expression patterns.

Tumor 13C lactate flux was significantly increased and 13C alanine flux was significantly decreased following partial RFA treatment to N1S1 tumors when compared to untreated tumors, which was associated with an increase in tumor Ki67 expression. However, no change was seen on h13C MRI between the RFA and control arms in MCA-RH7777 tumors, even though growth and total tumor burden progressed significantly more following RFA. In contrast to N1S1, there was also no difference between 13C lactate flux and 13C alanine flux within MCA-RH7777 tumors and the neighboring normal hepatic parenchyma, suggesting that glycolytic activity in these tumors did not drive RFA-stimulated progression. Targeting of glycolytic pathways as a potential therapy for HCC may therefore be limited to certain subtypes, and h13C MRI may be used to select for sensitivity.

Citation Format: Qianhui Dou, Aaron K. Grant, Cody Callahan, Muneeb Ahmed, Leo L. Tsai. Variations in glycolytic activity of HCC subtypes as monitored by in vivo h 13C MRI [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2807.

The Limit of Detection Matters: The Case for Benchmarking Severe Acute Respiratory Syndrome Coronavirus 2 Testing

Background

Resolving the coronavirus disease 2019 (COVID-19) pandemic requires diagnostic testing to determine which individuals are infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The current gold standard is to perform reverse-transcription polymerase chain reaction (PCR) on nasopharyngeal samples. Best-in-class assays demonstrate a limit of detection (LoD) of approximately 100 copies of viral RNA per milliliter of transport media. However, LoDs of currently approved assays vary over 10,000-fold. Assays with higher LoDs will miss infected patients. However, the relative clinical sensitivity of these assays remains unknown.

Methods

Here we model the clinical sensitivities of assays based on their LoD. Cycle threshold (Ct) values were obtained from 4700 first-time positive patients using the Abbott RealTime SARS-CoV-2 Emergency Use Authorization test. We derived viral loads from Ct based on PCR principles and empiric analysis. A sliding scale relationship for predicting clinical sensitivity was developed from analysis of viral load distribution relative to assay LoD.

Results

Ct values were reliably repeatable over short time testing windows, providing support for use as a tool to estimate viral load. Viral load was found to be relatively evenly distributed across log₁₀ bins of incremental viral load. Based on these data, each 10-fold increase in LoD is expected to lower assay sensitivity by approximately 13%.

Conclusions

The assay LoD meaningfully impacts clinical performance of SARS-CoV-2 tests. The highest LoDs on the market will miss a majority of infected patients. Assays should therefore be benchmarked against a universal standard to allow cross-comparison of SARS-CoV-2 detection methods.

Abstract 2785: 13C-MRI detects increased lactate flux in HCC following hepatic thermal A\ablation and correlates with PFKFB3 Expression

Thermal ablation (TA) is an accepted therapy for early HCC and hepatic metastases from colorectal and breast cancers. However, suboptimal TA is a risk factor for early HCC recurrence and has been associated with a reduction in overall survival. This effect has been attributed to hypoxic response in periablative tissue mediated by HIF-1. Malignant transformation leads to increased anaerobic glycolysis even under normoxic conditions. This process is detectable by hyperpolarized 13C MRI (h13C MRI), which enables real-time high-resolution imaging of the conversion from pyruvate to lactate and may be used as a potential predictor for therapeutic response in HCC. We have identified two potential metabolic regulators and therapeutic targets with a direct link to lactate flux which may be monitored with h13C MRI. PFKFB3 has been identified as a crucial metabolic factor in several cancer types, encoding for inducible 6-phosphofructo-2-kinase and enhancing production of F2,6P2, consequently activating PK1 and glycolysis. Expression levels of PFKFB3 have been found to be higher in malignancies than in normal tissues, attributed to loss of glycolytic control and accelerating neoplastic activity. Hexokinase 3 (HK3), a key catalyst in the first committed steps in glucose metabolism, is also a key promoter involved in epithelial-mesenchymal transition. When we exposed an HCC rat cell line, N1S1, to heat stress, simulating the marginal zone of TA therapy, 20%-90% of cells survived at 40°C-50°C and there was no survival by 55°C. 5-8 days following this treatment, cell proliferation and mRNA expression of glycolysis-related genes were analyzed. Cellular proliferation rate was significantly higher in the heat-treated groups. mRNA expression of PFKFB3 was increased after thermal treatment, while HK3 expression was significantly decreased. We then developed an in vivo orthotopic rat model of a solitary N1S1 HCC and used h13C MRI to measure in vivo tumor lactate flux in response to radiofrequency ablation (RFA), a type of thermal ablation, of adjacent normal hepatic tissue, simulating local treatment of a distant lesion. h13C MRI demonstrated significantly increased tumor 13C lactate flux in the RFA arm relative to the control group (change in lactate-to-pyruvate ratio of 0.236±0.278 vs -0.035±0.107, p=0.0465, n=6), while background liver lactate flux was unchanged. We found that this correlated with mRNA expression of PFKFB3 and HK3, which was statistically significantly greater within tumors from the RFA group compared to control tumors (PFKFB3, 1.052±0.091 vs 0.655±0.294, p=0.0004, n=6; HK3, 0.751±0.130 vs 0.501±0.163, p=0.0036, n=6). The PFKFB3 expression patterns were concordant between in vitro and in vivo experiments. Our data shows that PFKFB3 may be an attractive treatment target for HCC, and h13C MRI may be a noninvasive technique well-suited to monitor treatment response.

Citation Format: Qianhui Dou, Aaron K. Grant, Cody Callahan, David Mwin, Muneeb Ahmed, Leo L. Tsai. 13C-MRI detects increased lactate flux in HCC following hepatic thermal A\ablation and correlates with PFKFB3 Expression [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2785.

Nasal-Swab Testing Misses Patients with Low SARS-CoV-2 Viral Loads

The urgent need for large-scale diagnostic testing for SARS-CoV-2 has prompted pursuit of sample-collection methods of sufficient sensitivity to replace sampling of the nasopharynx (NP). Among these alternatives is collection of nasal-swab samples, which can be performed by the patient, avoiding the need for healthcare personnel and personal protective equipment. Previous studies have reached opposing conclusions regarding whether nasal sampling is concordant or discordant with NP. To resolve this disagreement, we compared nasal and NP specimens collected by healthcare workers in a cohort consisting of individuals clinically suspected of COVID-19 and outpatients known to be SARS-CoV-2 RT-PCR positive undergoing follow-up. We investigated three different transport conditions, including traditional viral transport media (VTM) and dry swabs, for each of two different nasal-swab collection protocols on a total of 308 study participants, and compared categorical results and Ct values to those from standard NP swabs collected at the same time from the same patients. All testing was performed by RT-PCR on the Abbott SARS-CoV-2 RealTime EUA (limit of detection [LoD], 100 copies viral genomic RNA/mL transport medium). We found high concordance (Cohen's kappa >0.8) only for patients with viral loads above 1,000 copies/mL. Those with viral loads below 1,000 copies/mL, the majority in our cohort, exhibited low concordance (Cohen's kappa = 0.49); most of these would have been missed by nasal testing alone. Previous reports of high concordance may have resulted from use of assays with higher LoD (≥1,000 copies/mL). These findings counsel caution in use of nasal testing in healthcare settings and contact-tracing efforts, as opposed to screening of asymptomatic, low-prevalence, low-risk populations. Nasal testing is an adjunct, not a replacement, for NP.

SARS-CoV2 Testing: The Limit of Detection Matters

Resolving the COVID-19 pandemic requires diagnostic testing to determine which individuals are infected and which are not. The current gold standard is to perform RT-PCR on nasopharyngeal samples. Best-in-class assays demonstrate a limit of detection (LoD) of ~100 copies of viral RNA per milliliter of transport media. However, LoDs of currently approved assays vary over 10,000-fold. Assays with higher LoDs will miss more infected patients, resulting in more false negatives. However, the false-negative rate for a given LoD remains unknown. Here we address this question using over 27,500 test results for patients from across our healthcare network tested using the Abbott RealTime SARS-CoV-2 EUA. These results suggest that each 10-fold increase in LoD is expected to increase the false negative rate by 13%, missing an additional one in eight infected patients. The highest LoDs on the market will miss a majority of infected patients, with false negative rates as high as 70%. These results suggest that choice of assay has meaningful clinical and epidemiological consequences. The limit of detection matters.

First Measurement of the Total Neutron Cross Section on Argon between 100 and 800 MeV

We report the first measurement of the neutron cross section on argon in the energy range of 100-800 MeV. The measurement was obtained with a 4.3-h exposure of the Mini-CAPTAIN detector to the WNR/LANSCE beam at LANL. The total cross section is measured from the attenuation coefficient of the neutron flux as it traverses the liquid argon volume. A set of 2631 candidate interactions is divided in bins of the neutron kinetic energy calculated from time-of-flight measurements. These interactions are reconstructed with custom-made algorithms specifically designed for the data in a time projection chamber the size of the Mini-CAPTAIN detector. The energy averaged cross section is 0.91±0.10(stat)±0.09(syst)  b. A comparison of the measured cross section is made to the GEANT4 and FLUKA event generator packages, where the energy averaged cross sections in this range are 0.60 and 0.68 b, respectively.

[Aging Brain Care Program from Indianapolis: Transferability to the German healthcare system]

BACKGROUND

New and innovative concepts of care management have been developed to improve the health of older adults with dementia and depression.

AIM

This article describes the American aging brain care (ABC) program and the possible transfer to the German healthcare system is discussed.

MATERIAL AND METHODS

The ABC medical home model in Indianapolis incorporates a specialized geriatric healthcare center which is affiliated to the Eskenazi Hospital as well as a program involving home-based domestic visits by healthcare personnel to affected people. The diagnoses are made in the geriatric center where therapy and treatment are also planned. These stages are carried out in a multiprofessional team, which identifies the individual needs of the patients and relatives and discusses these in family conferences as well as in close consultation with the primary care center of the hospital. The care, diagnosis and therapy are coordinated using a self-developed software for the program and via predetermined pathways and procedural instructions on the approach in the healthcare center and in the domestic visit program.

RESULTS AND CONCLUSION

From the perspective of the authors the core elements of the program include not only the use of a home-based care model but also the selection and training of a new type of front-line care provider. Models like the program presented here show great promise for meeting the demands of a rapidly expanding population of vulnerable older adults.

Qualitative needs assessment: healthcare experiences of underserved populations in Montgomery County, Virginia, USA

INTRODUCTION

Portions of Montgomery County, Virginia, are designated a Medically Underserved Area with a large portion of this population experiencing limited access to healthcare services. In September 2008, the Federal Bureau of Primary Care awarded the authors a planning grant to assess community need in Montgomery County and to develop a strategic plan to establish a Federally Qualified Health Center (FQHC) to best meet these needs. An FQHC is a federally funded clinic mandated to provide medical, dental and mental health services to underserved communities. As part of the planning process, the decision was made to include qualitative data to better understand the needs of underserved residents in the community. Descriptive studies of target populations can provide further insight into community priorities for effective health improvement and planning. The objective of the study was to investigate and describe the perceptions, beliefs and practices that impact healthcare utilization among underserved populations in Montgomery County, Virginia. This study was conducted as part of a comprehensive community assessment to determine the feasibility of developing a FQHC.

METHODS

Community focus groups were conducted with target populations which were representative of the community. A thematic analysis of the transcribed field notes and group interviews was conducted. Qualitative data analysis was performed using the Analysis Software for Word-Based Records (AnSWR) developed by the Centers for Disease Control.

RESULTS

Three important categories of beliefs which may impact healthcare utilization emerged from the discussions: (1) cultural health perceptions; (2) perceived barriers to care; and (3) coping strategies. Participants expressed a right to access quality care, preferred to spend money on basic living expenses rather than healthcare services; frequently neglected seeking care for adults while rarely neglecting to seek care for their children; valued but infrequently utilized preventative care; and had a lack of confidence in the care that was provided. Perceived barriers to healthcare services reported by participants included a lack of access to affordable care; complexities of health insurance and payer status; limited hours of clinic operation; lack of transportation and geographic distance; and the complexity of navigating the healthcare system. Finally, participants reported using various coping strategies to overcome barriers to accessing healthcare services. These strategies included delaying treatment and self-care; seeking financial and transportation assistance; and using community resources to navigate the system.

CONCLUSION

Establishing care that is culturally relevant, targets perceived barriers and incorporates and enhances coping strategies is needed to increase accessibility and utilization of preventative and comprehensive healthcare services. The findings from this study will assist in creating a strategic plan for a FQHC that capitalizes on community strengths while addressing the challenges and complex needs of the community.

Relatedness and social organization of coypus in the Argentinean pampas

Behavioural and trapping studies of the social organization of coypus have suggested the occurrence of kin groups and a polygynous mating system. We used 16 microsatellite markers to analyse parentage and relatedness relationships in two populations (Jáuregui and Villa Ruiz) in the Argentinean Pampas. At Jáuregui, a dominant male monopolized most paternities, leading to a high variance in reproductive success between males and a high level of polygyny. At Villa Ruiz, variance in reproductive success was low among resident males and males were the fathers of zero to four offspring each. For females, no significant differences were found. Two different social groups in each study site were used to assess genetic relatedness within and between groups. These groups were neighbouring at Jáuregui but not at Villa Ruiz. At Villa Ruiz, coypus were significantly more related within than between groups, suggesting that behavioural groups were also genetic ones, and adult females were more related within than between groups, as should be expected for kin groups. This relationship was not found at Jáuregui. Our results provide support to previous studies based on behavioural and trapping data, which indicate that coypus form social groups and have a polygynous mating system. However, we found differences in social organization between the two populations. This is the first study to determine parentage and/or relatedness in coypus.

A novel trinucleotide repeat expansion at chromosome 3q26.2 identified by a CAG/CTG repeat expansion detection array

CAG/CTG repeat expansions cause at least 12 different neurological disorders, and additional disorders of this type probably exist. Using the repeat expansion detection (RED) assay, we identified an expanded CAG/CTG repeat in a 50-year-old woman with an autosomal dominant syndrome with prominent progressive sensory neuropathy. The expansion could not be accounted for by any of the CAG/CTG repeats known to undergo expansion. To identify the locus of the expansion, we created a PCR array to assess the repeat length of all repeats of eight or more CAG or CTG triplets in the human genome. The expansion was localized to a repeat contained in an intron of a Genscan-predicted gene, 185 nt downstream of a predicted exon that is conserved through mouse. The closest experimentally verified gene in the region (TNIK, encoding a serine/threonine kinase) occurs approximately 63 Kb downstream from the repeat. The length of the expansion in the proband is 98 triplets. This repeat is not expanded in the proband's cousin (the only other affected family member for whom DNA is currently available) and no expansions were detected in a set of 230 patients with movement disorders of unknown cause. An expanded allele containing 58 triplets was detected in a single control individual, and no other expansions were detected in a set of 255 controls. The normal repeat length ranges from 5 to 30 triplets, with 8 triplets the most common allele. Our results suggest that this new repeat expansion is probably not the direct cause of the phenotype in the proband. Whether the repeat contributes to the patient's phenotype, or is associated with another phenotype, remains to be determined.

An unexpectedly high incidence of Epstein-Barr virus lymphoproliferative disease after CD34+ selected autologous peripheral blood stem cell transplant in neuroblastoma

The risk of Epstein–Barr virus lymphoproliferative disease (EBV-LPD) increases with the use of highly immunosuppressive therapies. Allogeneic BMT, especially supported by T-cell-depleted stem cell products, is a risk factor for EBV-LPD. Although the risk of EBV-LPD after autologous transplantation is low, case reports of this complication in the autologous setting exist. We report a higher incidence than previously described of EBV-LPD in children undergoing sequential high-dose chemotherapy supported with CD34 selected peripheral blood stem cells (CD34+ PBSC). The median time to LPD after tandem transplant was 3 months (range 1–5 months). Five patients out of 156 (3.5%) developed EBV-LPD while enrolled on two trials of tandem autologous SCT in high-risk pediatric malignancies. Both studies employed five cycles of induction therapy, followed by tandem autologous PBSC transplants. In all, 108 out of 156 patients received CD34+ PBSC; 48 received unselected PBSC. All patients contracting LPD were from the CD34 selected group. Treatment of EBV-LPD included rituximab in four out of five patients, IVIg in two out of five patients, and gancyclovir in two out of five patients. EBV-LPD resolved in four out of five patients. We conclude that the combination of tandem SCT and CD34 selection may have increased immunosuppression in these patients to a point where there is an elevated risk of EBV-LPD.

Novel CAG/CTG repeat expansion mutations do not contribute to the genetic risk for most cases of bipolar disorder or schizophrenia

The possible presence of anticipation in bipolar affective disorder and schizophrenia has led to the hypothesis that repeat expansion mutations could contribute to the genetic etiology of these diseases. Using the repeat expansion detection (RED) assay, we have systematically examined genomic DNA from 100 unrelated probands with schizophrenia and 68 unrelated probands with bipolar affective disorder for the presence of CAG/CTG repeat expansions. Our results show that 28% of the probands with schizophrenia and 30% of probands with bipolar disorder have a CAG/CTG repeat in the expanded range, but that each expansion could be explained by one of three nonpathogenic repeat expansions known to exist in the general population. We conclude that novel CAG/CTG repeat expansions are not a common genetic risk factor for bipolar disorder or schizophrenia.

A disorder similar to Huntington's disease is associated with a novel CAG repeat expansion

Huntington's disease (HD) is an autosomal dominant disorder characterized by abnormalities of movement, cognition, and emotion and selective atrophy of the striatum and cerebral cortex. While the etiology of HD is known to be a CAG trinucleotide repeat expansion, the pathways by which this mutation causes HD pathology remain unclear. We now report a large pedigree with an autosomal dominant disorder that is clinically similar to HD and that arises from a different CAG expansion mutation. The disorder is characterized by onset in the fourth decade, involuntary movements and abnormalities of voluntary movement, psychiatric symptoms, weight loss, dementia, and a relentless course with death about 20 years after disease onset. Brain magnetic resonance imaging scans and an autopsy revealed marked striatal atrophy and moderate cortical atrophy, with striatal neurodegeneration in a dorsal to ventral gradient and occasional intranuclear inclusions. All tested affected individuals, and no tested unaffecteds, have a CAG trinucleotide repeat expansion of 50 to 60 triplets, as determined by the repeat expansion detection assay. Tests for the HD expansion, for all other known CAG expansion mutations, and for linkage to chromosomes 20p and 4p were negative, indicating that this mutation is novel. Cloning the causative CAG expansion mutation for this new disease, which we have termed Huntington's disease-like 2, may yield valuable insight into the pathogenesis of HD and related disorders.

A repeat expansion in the gene encoding junctophilin-3 is associated with Huntington disease-like 2

We recently described a disorder termed Huntington disease-like 2 (HDL2) that completely segregates with an unidentified CAG/CTG expansion in a large pedigree (W). We now report the cloning of this expansion and its localization to a variably spliced exon of JPH3 (encoding junctophilin-3), a gene involved in the formation of junctional membrane structures.

A disorder similar to Huntington's disease is associated with a novel CAG repeat expansion

Huntington's disease (HD) is an autosomal dominant disorder characterized by abnormalities of movement, cognition, and emotion and selective atrophy of the striatum and cerebral cortex. While the etiology of HD is known to be a CAG trinucleotide repeat expansion, the pathways by which this mutation causes HD pathology remain unclear. We now report a large pedigree with an autosomal dominant disorder that is clinically similar to HD and that arises from a different CAG expansion mutation. The disorder is characterized by onset in the fourth decade, involuntary movements and abnormalities of voluntary movement, psychiatric symptoms, weight loss, dementia, and a relentless course with death about 20 years after disease onset. Brain magnetic resonance imaging scans and an autopsy revealed marked striatal atrophy and moderate cortical atrophy, with striatal neurodegeneration in a dorsal to ventral gradient and occasional intranuclear inclusions. All tested affected individuals, and no tested unaffecteds, have a CAG trinucleotide repeat expansion of 50 to 60 triplets, as determined by the repeat expansion detection assay. Tests for the HD expansion, for all other known CAG expansion mutations, and for linkage to chromosomes 20p and 4p were negative, indicating that this mutation is novel. Cloning the causative CAG expansion mutation for this new disease, which we have termed Huntington's disease-like 2, may yield valuable insight into the pathogenesis of HD and related disorders.

Purification and characterization of the tRNA-processing enzyme RNase BN

RNase BN, a tRNA-processing enzyme previously shown to be required for the 3'-maturation of certain bacteriophage T4-encoded tRNAs, was overexpressed and purified to near homogeneity from Escherichia coli. The purified enzyme, which is free of nucleic acid, is an alpha(2)-dimer with a molecular mass of approximately 65 kDa. RNase BN displays a number of unusual catalytic properties compared with the other exoribonucleases of E. coli. The enzyme is most active at pH 6.5 in the presence of Co(2+) and high concentrations of monovalent salts. It is highly specific for tRNA substrates containing an incorrect residue within the universal 3'-CCA sequence. Thus, tRNA-CU and tRNA-CA are effective substrates, whereas intact tRNA-CCA, elongated tRNA-CCA-Cn, phosphodiesterase-treated tRNA, and the closely related tRNA-CC are essentially inactive as substrates. RNA or DNA oligonucleotides also are not substrates. These data indicate that RNase BN has an extremely narrow substrate specificity. However, since tRNA molecules with incorrect residues within the -CCA sequence are not normally produced in E. coli, the role of RNase BN in uninfected cells remains to be determined.

Safety and efficacy of attempted vaginal birth after cesarean beyond the estimated date of delivery

OBJECTIVE

To provide data regarding safety and efficacy for women attempting a trial of labor following earlier cesarean birth who have reached their due date.

STUDY DESIGN

A computerized data base was analyzed to identify women who were at or beyond 40 weeks of gestation between January 1, 1995, and March 31, 1996. Ninety women attempted vaginal birth after cesarean (VBAC) during the study period; 90 controls were matched for age, race and parity. Delivery route and complications were outcome variables identified.

RESULTS

The rate of successful VBAC was 65.6% as compared to the 94.4% vaginal delivery rate among women who had not had a prior cesarean (P < .0001). Among women attempting VBAC, 62% of those who had no prior vaginal births successfully delivered vaginally, while 82% of women with one prior vaginal birth delivered vaginally (P < .0001). Women of greater parity were more successful at a trial of labor. Infectious morbidity was more common among women attempting VBAC than among those with no prior cesarean.

CONCLUSION

The patient and her family can be reassured that passing her due date does not alter the efficacy or safety of a trial of labor. No change in counseling is warranted simply due to the completion of 40 weeks' gestation.

Unstable expansion of the CAG trinucleotide repeat in MAB21L1: report of a second pedigree and effect on protein expression

MAB21L1, originally termed CAGR1, is the human homologue of the C. elegans cell fate determining gene mab21. MAB21L1, mapped to 13q13, contains a highly polymorphic 5' untranslated CAG repeat that normally ranges from six to 31 triplets in length. A pedigree has been previously reported in which the repeat length is expanded to 45-50 triplets and is transmitted unstably between generations; the expansion did not correlate to a clinical phenotype but did exhibit somatic mosaicism. We now report a second pedigree with an expanded and unstably transmitted MAB21L1 CAG repeat of similar length. The expansion is not clearly associated with a clinical phenotype, though the complexity of the pedigree renders any conclusion concerning phenotype-genotype relationships speculative. The expansion did not result in decreased expression of MAB21L1 protein. The length, C-G rich composition, somatic mosaicism, and unstable transmission of the expanded CAG repeat in MAB21L1 resemble the premutations observed in other genes, such as FMR1 and MDPK, in which longer expanded repeats are associated with a clinical phenotype. This raises the possibility that longer expansions in the MAB21L1 repeat may also be associated with a clinical phenotype.

Contrast magnetic resonance imaging in the assessment of myocardial viability in patients with stable coronary artery disease and left ventricular dysfunction

BACKGROUND

The utility of contrast MRI for assessing myocardial viability in stable coronary artery disease (CAD) with left ventricular dysfunction is uncertain. We therefore performed cine and contrast MRI in 24 stable patients with CAD and regional contractile abnormalities and compared MRI findings with rest-redistribution 201Tl imaging and dobutamine echocardiography.

METHODS AND RESULTS

Delayed MRI contrast enhancement patterns were examined from 3 to 15 minutes after injection of 0.1 mmol/kg IV gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA). Comparable MRI and 201Tl basal and midventricular short-axis images were subdivided into 6 segments. Segments judged nonviable by quantitative and qualitative assessment of 201Tl scans showed persistent, systematically greater MRI contrast signal intensity than segments judged viable (P</=0.002). Delayed contrast hyperenhancement also occurred in segments judged nonviable by dobutamine echocardiography (P</=0.03). The presence or absence of hyperenhancement correlated most closely with nonviability and viability, respectively, in segments that were akinetic or dyskinetic under resting conditions (83% concordance with 201Tl in both cases). In segments with resting hypokinesis, 58% of segments showing hyperenhancement were judged viable by 201Tl and may have represented an admixture of scar tissue and viable myocardium.

CONCLUSIONS

Delayed (by 3 to 15 minutes) hyperenhancement of Gd-DTPA contrast-enhanced MRI images occurs frequently in dysfunctional areas of the left ventricle in patients with stable CAD. Hyperenhancement is associated with nonviability by rest-redistribution 201Tl scintigraphy and dobutamine echocardiography, particularly in regions exhibiting resting akinesis/dyskinesis. The absence of hyperenhancement correlates with radionuclide and echocardiographic determinations of viability, regardless of resting contractile function.

Complications of the ketogenic diet

PURPOSE

The ketogenic diet has been successfully used in treatment of pediatric epilepsy for >70 years. Few serious complications caused by the diet have been reported. We report complications that have been experienced by children receiving the ketogenic diet.

METHODS

In a 22-month period, we treated 52 children with the classic ketogenic diet and monitored them in a prospective manner.

RESULTS

Five children (10%) experienced serious adverse events (AE) after initiation of the diet. Four patients (80%) were treated with valproate (VPA) in addition to the diet, as compared with 25 (53%) of the other 47 children. Two patients developed severe hypoproteinemia within 4 weeks of initiation of the diet, and 1 of them also developed lipemia and hemolytic anemia. A third child developed Fanconi's renal tubular acidosis within 1 month of diet initiation. Two other children manifested marked increases in liver function tests, 1 during the initiation phase and the other 13 months later.

CONCLUSIONS

Clinicians who wish to use the ketogenic diet must be aware of the potential of serious AE and possible interactions of the diet with VPA.

Histopathological reactions of the blue shark, Prionace glauca, to postlarvae of Hepatoxylon trichiuri (Cestoda: Trypanorhyncha: Hepatoxylidae) in relationship to scolex morphology

Postlarvae of the cestode Hepatoxylon trichiuri (Holten, 1802) were found attached to the surface of viscera of Prionace glauca (Linnaeus, 1758) taken from Atlantic coastal waters off the south coast of Massachusetts, USA. Gross anatomy of the attachment site shows a quadripartite rim surrounding a deep pit with holes corresponding to the penetration site of each tentacle. Hyperplasia of the liver capsule into outgrowths at the attachment site conform to the attachment of the bothridia. The cuboidal epithelium of the liver capsule became columnar forming papillary outgrowths, with a dense fibrotic reaction beneath the attachment site and infiltration by leukocytes and pigment containing granulocytic cells. Blood sinusoids beneath the attachment site are greatly enlarged. Postlarvae attached to the surface of the epigonal organs of three blue sharks were not accompanied by reactions. SEM examination of the scolex of H. trichiuri postlarvae revealed fused pairs of bothridia within infolded muscular lateral rims, porose tegument devoid of microtriches and a bilateral plane of symmetry in the tentacular armature.

Strategies for nutritional intervention in patients with renal failure

This review article discusses the evidence documenting the interrelationship between nutritional status and clinical outcome of the renal patient population. The limitations of accurately assessing the nutritional status of this patient group with commonly used indices are detailed. An overview of the history of nutrition supplementation as an intervention for the malnourished renal patient reveals that the efficacy of both enteral and parenteral methods has not been adequately explored to draw any firm conclusions. Based on available data, recommendations for providing nutrition care for the malnourished patient are provided. Therapeutics that are currently under investigation as future interventions for malnutrition are identified.

Contrast-enhanced magnetization transfer MR of the brain: importance of precontrast images

PURPOSE

To determine the importance of obtaining precontrast T1-weighted magnetization transfer (MT) MR images for better interpretation contrast-enhanced T1-weighted MT images.

METHODS

One hundred fifty-five patients referred for MR imaging of the brain were examined prospectively with noncontrast T1-weighted imaging, noncontrast T1-weighted imaging with MT, contrast-enhanced T1-weighted imaging, and contrast-enhanced T1-weighted imaging with MT. In the patients who had abnormally increased signal intensity on postcontrast images (with or without MT), the four imaging sequences were evaluated with regard to number of lesions and lesional signal intensity. For each of the sequences, two experienced neuroradiologists subjectively graded the lesions on a scale of 1 to 4 (4 being the most conspicuous) with regard to abnormally increased signal intensity.

RESULTS

Twenty-two of the 155 patients had increased signal intensity on one or more of the postcontrast sequences. Eight of these 22 patients had increased signal intensity of one or more lesions on images without MT. All these lesions were seen better on images obtained with MT. An additional six of the 22 patients had increased signal intensity of one or more lesions on images obtained with MT that was not detected on images obtained without MT. Eight of the 22 patients had no high signal intensity on noncontrast images with or without MT. One of the eight had increased number and conspicuity of lesions on postcontrast MT images.

CONCLUSIONS

A significant number of patients had increased signal intensity on noncontrast T1-weighted images with MT that was not seen on noncontrast T1-weighted images without MT. This high signal intensity was also visible on postcontrast MT images, and would have been mistaken for pathologic enhancement if noncontrast MT images had not been available for comparison.

cDNAs with long CAG trinucleotide repeats from human brain

Twelve diseases, most with neuropsychiatric features, arise from trinucleotide repeat expansion mutations. Expansion mutations may also cause a number of other disorders, including several additional forms of spinocerebellar ataxia, bipolar affective disorder, schizophrenia, and autism. To obtain candiate genes for these disorders, cDNA libraries from adult and fetal human brain were screened at high stringency for clones containing CAG repeats. Nineteen cDNAs were isolated and mapped to chromosomes 1, 2, 4, 6, 7, 8, 9, 12, 16, 19, 20, and X. The clones contain between 4 and 17 consecutive CAG, CTG, TCG, or GCA triplets. Clone H44 encodes 40 consecutive glutamines, more than any other entry in the nonredundant GenBank protein database and well within the range that causes neuronal degeneration in several of the glutamine expansion diseases. Eight cDNAs encode 15 or more consecutive glutamine residues, suggesting that the gene products may function as transcription factors, with a potential role in the regulation of neurodevelopment or neuroplasticity. In particular, the conceptual translation of clone CTG3a contains 18 consecutive glutamines and is 45% identical to the C-terminal 306 residues of the mouse numb gene product. These genes are therefore candidates for diseases featuring anticipation, neurodegeneration, or abnormalities of neurodevelopment.

Identification and characterization of the Escherichia coli rbn gene encoding the tRNA processing enzyme RNase BN

The gene encoding RNase BN was localized to 88 min on the Escherichia coli chromosome by a novel suppressor assay and conjugational and transductional analysis. Assay of subclones derived from lambda phage 543 of the Kohara library, which encompasses this region of the chromosome, for elevated RNase BN activity identified o290, a previously reported open reading frame, as the gene encoding RNase BN. Interruption of this gene with a Kan(r) cassette and introduction into the chromosome eliminated cellular RNase BN activity but had no effect on cell growth. On the basis of these data, we suggest that o290 be renamed rbn. Potential homologs of rbn in other organisms also were identified.

Medical care of illegal migrants intercepted on the high sea (Operation Prompt Return)

In July 1995, Operation Prompt Return was mounted to set up a facility on Wake Island in the mid-Pacific to process 158 illegal emigrants and return them to China. The deployed medical team screened and examined the travelers and the ship's crew. Initial major problems consisted of skin rashes, dental diseases, and signs of physical abuse. Subsequently, urogenital complaints, musculoskeletal pain, and newer cases of scabies were evaluated and treated. Problems relating to planning and provision of medical care to migrants were discussed and solutions were suggested.

Location of the central sulcus via cortical thickness of the precentral and postcentral gyri on MR

PURPOSE

To determine whether relative cortical thickness measurements of the precentral and postcentral gyri can be used to differentiate the central sulcus from adjacent cortical sulci.

METHODS

Turbo inversion-recovery MR imaging of the entire brain was done with scans parallel to the anterior commissure-posterior commissure line. Cortical thickness was measured in each hemisphere with a jeweler's eyepiece with 0.1-mm gradations. Three measurements were obtained perpendicular to the central, precentral, and superior frontal sulci, as determined by means of established anatomic methods. The ratios of cortical thickness on both sides of the central, precentral, and superior frontal sulci were calculated and compared.

RESULTS

The mean ratio of precentral/postcentral gyri was 1.64 for the right hemisphere and 1.53 for the left hemisphere. The mean cortical thickness ratios were as follows: 1.01 for the right hemisphere and 3.01 for the left hemisphere across the precentral sulcus, and 1.03 for the right hemisphere and 0.99 for the left hemisphere across the superior frontal sulcus.

CONCLUSION

Cortical thickness measurements across the central sulcus provide a method for locating the primary motor (precentral gyri) and primary somatosensory (postcentral gyri) cortices. The higher mean cortical thickness ratio across the central sulcus corresponds with known cytoarchitectonic relationships.

Management and prognosis of life-threatening bleeding during warfarin therapy. National Consortium of Anticoagulation Clinics

BACKGROUND

The incidence of explicity defined life-threatening bleeding during warfarin sodium therapy is largely unknown, as are the prognosis for and treatment of patients who have such bleeding. In addition, the location of the source of the life-threatening bleeding and the risk factors associated with life-threatening bleeding are not well-defined.

OBJECTIVES

To determine the incidence of explicitly defined life-threatening bleeding during warfarin therapy, to identify the site of bleeding, to determine the risk factors for life-threatening bleeding, and to determine the risk of subsequent bleeding among patients receiving warfarin therapy.

METHODS

A cross-sectional prevalence study was conducted and data were combined with those obtained during prospective observation of a dynamic cohort of patients followed up in 2 university-affiliated and 3 Veterans Administration anticoagulation clinics.

RESULTS

For this study, 1999 patients were followed up for 3865 patient-years; 32 patients (11 women, 21 men, mean age of 60 years) met criteria for life-threatening bleeding, an incidence of 0.83 events/100 patient-years (95% confidence interval, 0.54-1.12). The most common indication for warfarin was to prevent thromboembolism because the patient had a mechanical heart valve (17/32 patients, 53%). The gastrointestinal tract was the definite or likely site of bleeding in 21 (66%) of the 32 patients. The prothrombin time ratio was longer than 2.0 or the international normalized ratio was longer than 4.5 in 16 (55%) of the 29 patients in whom a coagulation time was measured. Fourteen (44%) of the 32 patients had a history of peptic ulcer disease or gastrointestinal bleeding. Warfarin was restarted in 26 (81%) of the 32 patients. Twenty-five of 26 patients were followed up for a median of 30 months (range, 5-143 months); 14 (56%) of the 25 patients had a subsequent bleeding event, with 8 (57%) of the 14 having 1 or more additional life-threatening bleeding events (1 fatal) after a median of 11.5 months (range, 0.5-22 months).

CONCLUSIONS

We conclude that in this cohort: (1) the incidence of life-threatening bleeding was rare, (2) the gastrointestinal tract was the site of bleeding in two thirds of the patients who experienced life-threatening bleeding, (3) most patients who experienced life-threatening bleeding had multiple risk factors for bleeding, including excessive anticoagulation, and (4) the risk of subsequent bleeding was extremely high among the patients who continued to receive warfarin therapy.

Management and prognosis of life-threatening bleeding during warfarin therapy. National Consortium of Anticoagulation Clinics

BACKGROUND

The incidence of explicity defined life-threatening bleeding during warfarin sodium therapy is largely unknown, as are the prognosis for and treatment of patients who have such bleeding. In addition, the location of the source of the life-threatening bleeding and the risk factors associated with life-threatening bleeding are not well-defined.

OBJECTIVES

To determine the incidence of explicitly defined life-threatening bleeding during warfarin therapy, to identify the site of bleeding, to determine the risk factors for life-threatening bleeding, and to determine the risk of subsequent bleeding among patients receiving warfarin therapy.

METHODS

A cross-sectional prevalence study was conducted and data were combined with those obtained during prospective observation of a dynamic cohort of patients followed up in 2 university-affiliated and 3 Veterans Administration anticoagulation clinics.

RESULTS

For this study, 1999 patients were followed up for 3865 patient-years; 32 patients (11 women, 21 men, mean age of 60 years) met criteria for life-threatening bleeding, an incidence of 0.83 events/100 patient-years (95% confidence interval, 0.54-1.12). The most common indication for warfarin was to prevent thromboembolism because the patient had a mechanical heart valve (17/32 patients, 53%). The gastrointestinal tract was the definite or likely site of bleeding in 21 (66%) of the 32 patients. The prothrombin time ratio was longer than 2.0 or the international normalized ratio was longer than 4.5 in 16 (55%) of the 29 patients in whom a coagulation time was measured. Fourteen (44%) of the 32 patients had a history of peptic ulcer disease or gastrointestinal bleeding. Warfarin was restarted in 26 (81%) of the 32 patients. Twenty-five of 26 patients were followed up for a median of 30 months (range, 5-143 months); 14 (56%) of the 25 patients had a subsequent bleeding event, with 8 (57%) of the 14 having 1 or more additional life-threatening bleeding events (1 fatal) after a median of 11.5 months (range, 0.5-22 months).

CONCLUSIONS

We conclude that in this cohort: (1) the incidence of life-threatening bleeding was rare, (2) the gastrointestinal tract was the site of bleeding in two thirds of the patients who experienced life-threatening bleeding, (3) most patients who experienced life-threatening bleeding had multiple risk factors for bleeding, including excessive anticoagulation, and (4) the risk of subsequent bleeding was extremely high among the patients who continued to receive warfarin therapy.

cDNA cloning of a human homologue of the Caenorhabditis elegans cell fate-determining gene mab-21: expression, chromosomal localization and analysis of a highly polymorphic (CAG)n trinucleotide repeat

The two most consistent features of the diseases caused by trinucleotide repeat expansion-neuropsychiatric symptoms and the phenomenon of genetic anticipation-may be present in forms of dementia, hereditary ataxia, Parkinsonism, bipolar affective disorder, schizophrenia and autism. To identify candidate genes for these disorders, we have screened human brain cDNA libraries for the presence of gene fragments containing polymorphic trinucleotide repeats. Here we report the cDNA cloning of CAGR1, originally detected in a retinal cDNA library. The 2743 bp cDNA contains a 1077 bp open reading frame encoding 359 amino acids. This amino acid sequence is homologous (56% amino acid identify and 81% amino acid conservation) to the Caenorhabditis elegans cell fate-determining protein mab-21. CAGR1 is expressed in several human tissues, most prominently in the cerebellum, as a message of approximately 3.0 kb. The gene was mapped to 13q13, just telomeric to D13S220. A 5'-untranslated CAG trinucleotide repeat is highly polymorphic, with repeat length ranging from six to 31 triplets and a heterozygosity of 87-88% in 684 chromosomes from several human populations. One allele from an individual with an atypical movement disorder and bipolar affective disorder type II contains 46 triplets, 15 triplets longer than any other allele detected. Though insufficient data are available to link the long repeat to this clinical phenotype, an expansion mutation of the CAGR1 repeat can be considered a candidate for the etiology of disorders with anticipation or developmental abnormalities, and particularly any such disorders linked to chromosome 13.

Anticipation and instability of IT-15 (CAG)n repeats in parent-offspring pairs with Huntington disease

Huntington disease (HD) is an autosomal dominant degenerative disorder caused by an expanded and unstable trinucleotide repeat (CAG)n in a gene (IT-15) on chromosome 4. HD exhibits genetic anticipation--earlier onset in successive generations within a pedigree. From a population-based clinical sample, we ascertained parent-offspring pairs with expanded alleles, to examine the intergenerational behavior of the trinucleotide repeat and its relationship to anticipation. We find that the change in repeat length with paternal transmission is significantly correlated with the change in age at onset between the father and offspring. When expanded triplet repeats of affected parents are separated by median repeat length, we find that the longer paternal and maternal repeats are both more unstable on transmission. However, unlike in paternal transmission, in which longer expanded repeats display greater net expansion than do shorter expanded repeats, in maternal transmission there is no mean change in repeat length for either longer or shorter expanded repeats. We also confirmed the inverse relationship between repeat length and age at onset, the higher frequency of juvenile-onset cases arising from paternal transmission, anticipation as a phenomenon of paternal transmission, and greater expansion of the trinucleotide repeat with paternal transmission. Stepwise multiple regression indicates that, in addition to repeat length of offspring, age at onset of affected parent and sex of affected parent contribute significantly to the variance in age at onset of the offspring. Thus, in addition to triplet repeat length, other factors, which could act as environmental factors, genetic factors, or both, contribute to age at onset. Our data establish that further expansion of paternal repeats within the affected range provides a biological basis of anticipation in HD.

Cocaine exposure during pregnancy: improving assessment with radioimmunoassay of maternal hair

OBJECTIVE

To compare radioimmunoassay of postpartum maternal hair samples with a structured maternal interview for the detection of cocaine use during pregnancy.

METHODS

Radioimmunoassay of hair samples obtained postpartum was compared with self-report of cocaine use obtained by confidential, structured interviews of 405 postpartum women.

RESULTS

Cocaine or benzoylecgonine was detected in the hair samples of 129 of the 148 women (87%) who reported using cocaine at least once during pregnancy. Thirty-six of 257 women (14%) who reported that they had used no cocaine during pregnancy had positive hair tests. Positive hair assay with negative self-report was significantly more common among women who were unmarried (P = .001), African-American (P < .001), and multiparous (P = .035).

CONCLUSIONS

Hair analysis is a valuable complement to maternal self-report by interview. The methods used together provide a useful clinical and research technique yielding a comprehensive estimate of gestational cocaine exposure. Either method alone may result in misclassification of gestational cocaine exposure.

Drake Chemical Workers' Health Registry: coping with community tension over toxic exposures

BACKGROUND

Programs to communicate health risk information and to protect the health of groups exposed to toxic substances need to tailor interventions to the political, economic, and cultural situation of the at-risk group. In particular, such programs must often cope with exceptional community tension and conflict over these exposures.

METHODS

This article uses interviews and written materials to document and describe the state of affairs that led up to community tension over an occupational exposure to a bladder carcinogen. The article describes the planning and design of a program to provide medical surveillance to workers, which also alleviated community concern.

RESULTS

The Drake Chemical Workers' Health Registry coped successfully with community conflict and obtained a high participation rate.

CONCLUSIONS

General recommendations include the following: avoid identification with extraneous agendas; know the community and maintain communication; and match the intervention to the evolution of the community conflict.