Hepatocellular carcinoma in Pacific Islanders: comparison of Pacific Island-born vs. US-born

Aim: To describe demographic, clinical, and outcome differences in Pacific Island-born (PI-born) compared to US-born hepatocellular carcinoma (HCC) patients of Pacific Island ancestry within a clinical cohort in Hawaii. Methods: A prospectively collected database of 1608 patients diagnosed with HCC over a 30-year period (1993-2022) identified 252 patients of Pacific Islander ethnicity. Data collected: demographics, medical history, laboratory data, tumor characteristics, treatment, and survival. Patients were divided into two groups: PI-born and US-born. Categorical variables were analyzed using ANOVA and chi-square analysis. Odds ratios with 95% confidence intervals were calculated using univariate and multivariate logistic regression. Overall survival was evaluated using Kaplan-Meier analysis. Results: PI-born patients were younger (57.3 vs. 61.8 years, P = 0.002) and more likely to have hepatitis B (OR 14.10, 7.50-26.50) and underlying cirrhosis (OR 2.28, 1.17-4.45). In comparison, US-born patients had a significantly higher likelihood of Hepatitis C, nonalcoholic steatohepatitis/nonalcoholic fatty liver disease, history of non-HCC cancer, and positive smoking history compared to PI-born patients. PI-born patients were more likely to forego treatment (OR 3.22, 1.77-5.87) and be lost to follow-up (OR 9.21, 1.97-43.03). Both groups were equally likely to have the opportunity for curative surgical treatment (liver resection or transplant). US-born status was associated with higher mortality risk, while transplantation was associated with lower mortality risk. The PI-born cohort demonstrated higher overall survival at 3 and 5 years compared to US-born. Conclusion: HBV remains the primary risk factor for HCC in PI-born patients, whereas HCC in US-born patients is more associated with the adoption of a Westernized lifestyle.

Serum metabolite profiles are associated with the presence of advanced liver fibrosis in Chinese patients with chronic hepatitis B viral infection

BACKGROUND

Accurate and noninvasive diagnosis and staging of liver fibrosis are essential for effective clinical management of chronic liver disease (CLD). We aimed to identify serum metabolite markers that reliably predict the stage of fibrosis in CLD patients.

METHODS

We quantitatively profiled serum metabolites of participants in 2 independent cohorts. Based on the metabolomics data from cohort 1 (504 HBV associated liver fibrosis patients and 502 normal controls, NC), we selected a panel of 4 predictive metabolite markers. Consequently, we constructed 3 machine learning models with the 4 metabolite markers using random forest (RF), to differentiate CLD patients from normal controls (NC), to differentiate cirrhosis patients from fibrosis patients, and to differentiate advanced fibrosis from early fibrosis, respectively.

RESULTS

The panel of 4 metabolite markers consisted of taurocholate, tyrosine, valine, and linoelaidic acid. The RF models of the metabolite panel demonstrated the strongest stratification ability in cohort 1 to diagnose CLD patients from NC (area under the receiver operating characteristic curve (AUROC) = 0.997 and the precision-recall curve (AUPR) = 0.994), to differentiate fibrosis from cirrhosis (0.941, 0.870), and to stage liver fibrosis (0.918, 0.892). The diagnostic accuracy of the models was further validated in an independent cohort 2 consisting of 300 CLD patients with chronic HBV infection and 90 NC. The AUCs of the models were consistently higher than APRI, FIB-4, and AST/ALT ratio, with both greater sensitivity and specificity.

CONCLUSIONS

Our study showed that this 4-metabolite panel has potential usefulness in clinical assessments of CLD progression in patients with chronic hepatitis B virus infection.

Ursodeoxycholic acid accelerates bile acid enterohepatic circulation

BACKGROUND AND PURPOSE

Ursodeoxycholic acid (UDCA) is the first-line treatment for primary biliary cholangitis, but its effects on the enterohepatic circulation of bile acid (BA) have been under-investigated. Therefore, we studied the influence of UDCA on BA enterohepatic circulation in vivo and the mechanisms by which UDCA affects the BA kinetics.

EXPERIMENTAL APPROACH

Mice were treated with UDCA and other BAs to observe changes in BA pool and BA transporters involved in enterohepatic circulation. Isotope dilution techniques and biochemical analyses were applied to study BA kinetics after oral administration of UDCA, and the mechanism involved.

KEY RESULTS

Oral administration of UDCA in mice reduced the overall BA pool and produced a unique BA profile with high-abundance conjugated UDCA species, including tauroursodeoxycholic acid (TUDCA) and GUDCA. We found increased expression of several main BA transporters in the ileum and liver. BA kinetic experiment showed that feeding UDCA shortened cycling time of BA and accelerated BA enterohepatic circulation. Additionally, we found evidence that the effect of UDCA administration on accelerating BA enterohepatic circulation was due to the inhibition of farnesoid X receptor (FXR) signalling in the ileum and FGF15/19 in the liver.

CONCLUSION AND IMPLICATIONS

Oral administration of UDCA produced a unique BA profile with high-abundance TUDCA and GUDCA and significantly accelerated BA enterohepatic circulation through the inhibition of intestinal FXR signalling and reduced level of FGF15/19, which in turn, induced the expression of BA transporters in the liver. These findings highlight a critical role for UDCA in maintaining the homeostasis of BA enterohepatic circulation in vivo.

Underlying liver disease and advanced stage liver cancer are associated with elevated neutrophil-lymphocyte ratio

Background/Aims

Inflammation-based scores, such as the neutrophil-to-lymphocyte ratio (NLR), have been associated with prognosis in hepatocellular carcinoma (HCC); but variable cut-off values and potential lack of specificity have limited the utility of NLR. This study evaluates NLR in a large cohort of HCC patients.

Methods

We retrospectively reviewed 789 HCC cases (1993–2017) for demographics, tumor characteristics, treatment, and survival. NLR was stratified into NLR ≥1.5 and NLR ≥3 and analyzed for correlation with American Joint Committee on Cancer (AJCC) and Barcelona Clinic Liver Cancer (BCLC) stages. In 235 patients who underwent liver resection, survival and recurrence were evaluated by NLR.

Results

In 789 HCC cases, mean NLR was increased with advanced AJCC and BCLC stages. Hepatitis C patients were less likely to have NLR ≥1.5 and ≥3. Non-alcoholic steatohepatitis patients were more likely to have NLR ≥3. Patients with tumor size >5 cm, rupture, or macrovascular invasion were more likely to have NLR ≥3. In patients treated with resection, NLR ≥3 predicted early recurrence (odds ratio [OR] 4.14, P<0.01) and overall recurrence (OR 4.05, P<0.01). Mean NLR was 4.30 in those with recurrence and 2.75 in those without recurrence. Patients with NLR ≥3 showed significantly worse survival compared to those with NLR <3 (P<0.01 by log-rank test).

Conclusions

Elevated NLR is associated with advanced cancer stage and aggressive tumor characteristics, such as large size, rupture, and invasion. NLR ≥3 was associated with early and overall recurrence after resection but varied with etiology. NLR may be a useful biomarker in predicting recurrence for HCC patients undergoing curative resection, but further studies are required to elucidate the effect of disease etiology.

Clinical prediction of HBV and HCV related hepatic fibrosis using machine learning

Clinical prediction of advanced hepatic fibrosis (HF) and cirrhosis has long been challenging due to the gold standard, liver biopsy, being an invasive approach with certain limitations. Less invasive blood test tandem with a cutting-edge machine learning algorithm shows promising diagnostic potential.

In this study, we constructed and compared machine learning methods with the FIB-4 score in a discovery dataset (n = 490) of hepatitis B virus (HBV) patients. Models were validated in an independent HBV dataset (n = 86). We further employed these models on two independent hepatitis C virus (HCV) datasets (n = 254 and 230) to examine their applicability.

In the discovery data, gradient boosting (GB) stably outperformed other methods as well as FIB-4 scores (p < .001) in the prediction of advanced HF and cirrhosis. In the HBV validation dataset, for classification between early and advanced HF, the area under receiver operating characteristic curves (AUROC) of GB model was 0.918, while FIB-4 was 0.841; for classification between non-cirrhosis and cirrhosis, GB showed AUROC of 0.871, while FIB-4 was 0.830. Additionally, GB-based prediction demonstrated good classification capacity on two HCV datasets while higher cutoffs for both GB and FIB-4 scores were required to achieve comparable specificity and sensitivity.

Using the same parameters as FIB-4, the GB-based prediction system demonstrated steady improvements relative to FIB-4 in HBV and HCV cohorts with different cutoff values required in different etiological groups. A user-friendly web tool, LiveBoost, makes our prediction models freely accessible for further clinical studies and applications.

Abstract 4708: Treatment-associated changes in whole-body metabolic tumor volume on 18F-fluorocholine PET/CT: potential prognostic value in castrate-resistant prostate cancer

Background: Fluorine-18 fluorocholine (FC) positron emission tomography/ computed tomography (PET/CT) is a promising molecular imaging technique for whole-body detection of prostate cancer that is under investigational status in the United States. This study explores the potential prognostic value of globally measuring metabolic tumor burden using FC PET/CT in castrate-resistant prostate cancer (CRPC).

Methods: Following written informed consent, 30 patients with CRPC were enrolled into clinicaltrials.gov registered trials of FC PET/CT (NCT00928252 and NCT00928174). Whole-body FC PET/CT scans were obtained before and during treatment. The average time interval to follow-up FC PET/CT was 67 days, with intervening treatments consisting of chemotherapy in 11 patients and second-line androgen manipulation in 19 patients. Kaplan Meier analysis was applied to evaluate interval changes in prostate specific antigen (PSA) level, net metabolically active tumor volume (net MATV, calculated using automated image segmentation), and maximum standardized uptake value of the most active tumor found on each scan (matSUVmax) as survival factors. Declines of &gt; 30% were prospectively evaluated as definitions of treatment response for these measures.

Results: Baseline net MATV (range 0.12 cc to 1543.9 cc, median 52.6 cc) correlated significantly with baseline PSA level (r = 0.65, p = 0.0001) and matSUVmax (r = 0.42, p = 0.02). Baseline PSA level did not correlate with baseline matSUVmax (r = 0.11, p = 0.55). Change in net MATV (range +1294.93 to -1233.86 cc, median -2.59 cc), reflecting changes in whole body tumor volume ranging from 181% increase to 100% decrease, correlated significantly with change in matSUVmax (r = 0.41, p = 0.02) but not change in PSA (r = 0.17 , r = 0.36). Median duration of follow-up in surviving patients was 23 months (range 6 - 38 months). Longer overall survival was associated with treatment response based on net MATV (log-rank p = 0.04), but not PSA (log-rank p = 0.16) or SUV (log-rank p = 0.19).

Conclusion: Whole-body quantification of the change in metabolically-active tumor volume using FC PET/CT may have therapeutic predictive value in CRPC.

Translational Significance:

Survival rates in CRPC may vary as a function of metastatic disease burden. FC PET/CT can globally depict the distribution of metastatic disease in CRPC and enables whole-body volumetric measurements of metastatic tumor activity. This preliminary study suggests that changes in overall tumor burden as depicted by this non-FDA approved PET tracer may have prognostic value in CRPC.

Citation Format: Sandi Kwee, John Lim, Kathleen Kromer-Baker, Kyle Miyazaki, Miles Sato, Dayna Lucuab-Fegurgur, Marc N. Coel. Treatment-associated changes in whole-body metabolic tumor volume on 18F-fluorocholine PET/CT: potential prognostic value in castrate-resistant prostate cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4708. doi:10.1158/1538-7445.AM2014-4708

Viral hepatitis markers in liver tissue in relation to serostatus in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) incidence is increasing in the United States. Hepatitis B virus (HBV) and hepatitis C virus (HCV) are major causes of HCC. Hepatitis infection in patients with HCC is generally diagnosed by serology, which is not always consistent with the presence of HBV and HCV in the liver. The relationship of liver viral status to serostatus in hepatocarcinogenesis is not fully understood.

METHODS

HBV and HCV were evaluated in formalin-fixed, paraffin-embedded liver tissue specimens in a retrospective study of 61 U.S. HCC cases of known serologic status. HBV DNA and HCV RNA were detected by PCR, reverse transcription PCR (RT-PCR), and pyrosequencing, and HBsAg and HBcAg were evaluated by immunohistochemistry.

RESULTS

Viral markers were detected in the liver tissue of 25 of 61 (41%) HCC cases. Tissue viral and serologic status were discordant in 27 (44%) cases, including those with apparent "occult" infection. Specifically, HBV DNA was detected in tissue of 4 of 39 (10%) serum HBsAg (-) cases, including 1 anti-HCV(+) case; and HCV RNA was detected in tissue of 3 of 42 (7%) anti-HCV seronegative cases, including two with serologic evidence of HBV.

CONCLUSIONS

Viral hepatitis, including HBV-HCV coinfection, may be unrecognized in up to 17% of patients with HCC when based on serology alone. Further research is needed to understand the clinical significance of viral makers in liver tissue of patients with HCC in the absence of serologic indices.

IMPACT

The contribution of HBV and HCV to the increasing incidence of HCC in the United States may be underestimated.

Elucidating the landscape of aberrant DNA methylation in hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is one of the most common cancers and frequently presents with an advanced disease at diagnosis. There is only limited knowledge of genome-scale methylation changes in HCC.

Methods and Findings

We performed genome-wide methylation profiling in a total of 47 samples including 27 HCC and 20 adjacent normal liver tissues using the Illumina HumanMethylation450 BeadChip. We focused on differential methylation patterns in the promoter CpG islands as well as in various less studied genomic regions such as those surrounding the CpG islands, i.e. shores and shelves. Of the 485,577 loci studied, significant differential methylation (DM) was observed between HCC and adjacent normal tissues at 62,692 loci or 13% (p<1.03e-07). Of them, 61,058 loci (97%) were hypomethylated and most of these loci were located in the intergenic regions (43%) or gene bodies (33%). Our analysis also identified 10,775 differentially methylated (DM) loci (17% out of 62,692 loci) located in or surrounding the gene promoters, 4% of which reside in known Differentially Methylated Regions (DMRs) including reprogramming specific DMRs and cancer specific DMRs, while the rest (10,315) involving 4,106 genes could be potential new HCC DMR loci. Interestingly, the promoter-related DM loci occurred twice as frequently in the shores than in the actual CpG islands. We further characterized 982 DM loci in the promoter CpG islands to evaluate their potential biological function and found that the methylation changes could have effect on the signaling networks of Cellular development, Gene expression and Cell death (p = 1.0e-38), with BMP4, CDKN2A, GSTP1, and NFATC1 on the top of the gene list.

Conclusion

Substantial changes of DNA methylation at a genome-wide level were observed in HCC. Understanding epigenetic changes in HCC will help to elucidate the pathogenesis and may eventually lead to identification of molecular markers for liver cancer diagnosis, treatment and prognosis.

Abstract 4998: Genome-wide methylation profiling in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common cancers and frequently presents with an advanced disease. Although it has been shown that a variety of epigenetic alterations can cause molecular heterogeneity of liver tumors, these studies have focused on specific genes, especially oncogenes and tumor suppressor genes. There is limited knowledge of the genome-wide methylation status in liver tumors and how this may potentially contribute to carcinogenesis and prognosis. We conducted genome-wide methylation profiling in a set of liver tumors. A pilot study was first performed on DNA from paired fresh frozen tumor and adjacent normal tissues from 5 patients. Genome-wide methylation profiles were created using Infinium Human Methylation 450K BeadChips. GenomeStudio was used to normalize data and to identify differentially methylated (DM) genes in tumor vs. normal tissue with False Discovery Rate (FDR) adjustment. Biological functions of the DM genes were assigned using the Ingenuity Pathway Analysis (IPA). Of the 485,577 CpG loci studied, significant DM loci were observed between normal and tumor tissues at 4% (17,612 CpGs) with an adjusted p-value &lt; 0.001. Interestingly, 92% (15,712 CpGs) of the observed DNA methylation changes corresponded to general hypomethylation in tumor tissues, which was focused on promoter regions (741 out of 1,450 CpGs, 51%) and especially in promoter CpG islands (n=553, 74%). Conversely, hypomethylated CpGs were mostly observed in gene body and intergenic regions (12,343 out of 15,712 CpGs, 78%). Since the CpG islands in promoter regions can directly regulate gene expression levels, 428 genes including 12 miRNAs co-located with the significant DM CpGs (553 hypermethylated and 102 hypomethylated CpGs) in promoter region CpG islands were characterized for their biological function and potential role in liver cancer. IPA analysis showed Tissue and Cellular Development (p=1.0e-41), Cellular Growth and Proliferation (p=1.0e-14), and Gene Expression and Cell cycle (p=1.0e-12) as top networks. In particular, a top canonical pathway indicated 24 genes associated with the G-protein Coupled Receptor Signaling (p=3.12e-4) which is a key factor in transactivation of the commonly altered EGFR pathway in HCC development. Moreover, Nutritional Disease, with genes related to obesity (12 genes), weight loss (6 genes) and weight gain (4 genes) was observed as a top biological functional category (p&lt;0.05). In addition, HCC related genes including TP73, HOXA9, TRIL, RASL10A and IGF2BP1 were differentially methylated between tumors and normals. In summary, we are performing genome-wide profiling of differentially methylated genes in HCC using DNA from tumor and normal tissue samples contributed to our biorepository. We expect to confirm the pathways preliminarily identified as being involved in liver carcinogenesis by obtaining methylation profiles from a larger set of patients with liver tumors.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4998. doi:1538-7445.AM2012-4998

Measurement of circulating cell-free DNA in relation to 18F-fluorocholine PET/CT imaging in chemotherapy-treated advanced prostate cancer

Purpose: To examine the effects of chemotherapy on circulating cell‐free DNA (cfDNA) composition in relation to investigational whole‐body measurement of tumor activity by fluorine‐18 fluorocholine (FCH) positron emission tomography/computed tomography (PET/CT) in hormone‐refractory prostate cancer (HRPC).

Methods: Serial FCH PET/CT scans were performed in eight patients with HRPC receiving docetaxel‐based chemotherapy. Corresponding serial cfDNA samples were characterized by microfluidic electrophoresis, quantified by real‐time PCR, and compared with PET/CT results. Promoter methylation of two prostate cancer‐associated genes, GSTP1 and RARB2, was assessed by methylation‐specific PCR of bisulfite‐converted cfDNA.

Results: Plasma cfDNA concentrations increased significantly from 13.3 ng/mL at baseline to 46.8 ng/mL and 50.9 ng/mL after one and three treatment cycles, respectively (p= 0.001). GSTP1 and/or RARB2 promoter methylation was identified in all pretreatment samples. The appearance of large (200 bp–10.4 kb) cfDNA fragments was noted in posttreatment samples along with loss of methylation at GSTP1 and/or RARB2. Tumor activity on PET/CT correlated with cfDNA concentration (r=−0.50, p= 0.01). Patients meeting criteria for PET tumor response had significantly lower pretreatment cfDNA levels than those who did not (8.0 vs. 16.4 ng/mL, p= 0.03).

Conclusions: Chemotherapy is associated with significant changes in plasma cfDNA content and FCH PET/CT‐detected tumor activity. These interrelated measures are potential candidate markers of therapeutic response in HRPC. Clin Trans Sci 2012; Volume #: 1–6

Healthcare disparities in Asians and Pacific Islanders with hepatocellular cancer

BACKGROUND

Hawaii has the highest incidence of hepatocellular cancer (HCC) in the United States and the largest proportion of Asians and Pacific Islanders. HCC studies generally combine these groups into 1 ethnicity, and we sought to examine differences between Asian and Pacific Islander subpopulations.

METHODS

Demographic, clinical, and treatment data for 617 patients with HCC (420 Asians, 114 whites, and 83 Pacific Islanders) were reviewed. Main outcome measures included HCC screening and liver transplantation.

RESULTS

Asian and Pacific Islander subgroups had significantly more immigrants, and age was different between groups. Compared with whites, Pacific Islanders and Filipinos had less HCC screening and liver transplantation procedures, fewer met Milan criteria, and a smaller proportion of those with Milan criteria actually underwent transplantation.

CONCLUSIONS

There were significant differences in risk factors, clinical presentation, treatment, and access to care among Asian, Pacific Islander, and white patients with HCC. Future HCC studies may benefit from differentiating subgroups within Asian and Pacific Islander populations to better focus these efforts.

Cushing’s syndrome caused by an ACTH-producing large cell neuroendocrine carcinoma of the gallbladder

Malignancies of the gallbladder, including neuroendocrine tumors, are uncommon, mostly found incidentally after cholecystectomy and are frequently asymptomatic in the early stages, but highly fatal. Limited data is available on adrenocorticotropic hormone (ACTH)-producing neuroendocrine tumors specifically originating from the gallbladder. We report the clinical and radiographic findings, which included positron emission tomography and computed tomography, of a patient with a gallbladder mass who presented with Cushing’s syndrome. Subsequently, a diagnosis of ACTH-producing large cell neuroendocrine carcinoma of the gallbladder was made. Despite being rare and having a poor prognosis, hormone-producing neuroendocrine tumors should be part of the differential diagnosis in the approach of patients with Cushing’s syndrome.

The effects of radiofrequency fields on cell proliferation are non-thermal

The number of reports on the effects induced by radiofrequency (RF) electromagnetic fields and microwave (MW) radiation in various cellular systems is still increasing. Until now no satisfactory mechanism has been proposed to explain the biological effects of these fields. One of the current theories is that heat generation by RF/MW is the cause, in spite of the fact that a great number of studies under isothermal conditions have reported significant cellular changes after exposure to RF/MW. Therefore, this study was undertaken to investigate which effect MW radiation from these fields in combination with a significant change of temperature could have on cell proliferation. The experiments were performed on the same cell line, and with the same exposure system as in a previous work [S. Kwee, P. Raskmark, Changes in cell proliferation due to environmental non-ionizing radiation: 2. Microwave radiation, Bioelectrochem. Bioenerg., 44 (1998), pp. 251-255]. The field was generated by signal simulation of the Global System for Mobile communications (GSM) of 960 MHz. Cell cultures, growing in microtiter plates, were exposed in a specially constructed chamber, a Transverse Electromagnetic (TEM) cell. The Specific Absorption Rate (SAR) value for each cell well was calculated for this exposure system. However, in this study the cells were exposed to the field at a higher or lower temperature than the temperature in the field-free incubator i.e., the temperature in the TEM cell was either 39 or 35 +/- 0.1 degrees C. The corresponding sham experiments were performed under exactly the same experimental conditions. The results showed that there was a significant change in cell proliferation in the exposed cells in comparison to the non-exposed (control) cells at both temperatures. On the other hand, no significant change in proliferation rate was found in the sham-exposed cells at both temperatures. This shows that biological effects due to RF/MW cannot be attributed only to a change of temperature. Since the RF/MW induced changes were of the same order of magnitude at both temperatures and also comparable to our previous results under isothermal conditions at 37 degrees C, cellular stress caused by electromagnetic fields could initiate the changes in cell cycle reaction rates. It is widely accepted that certain classes of heat-shock proteins are involved in these stress reactions.

Positron emission tomography study of voluntary saccadic eye movements and spatial working memory

1. The purpose of this study is to define the cortical regions that subserve voluntary saccadic eye movements and spatial working memory in humans. 2. Regional cerebral blood flow (rCBF) during performance of oculomotor tasks was measured with [15O]-H2O positron emission tomography (PET). Eleven well-trained, healthy young adults performed the following tasks: visual fixation, visually guided saccades, antisaccades (a task in which subjects made saccades away from rather than toward peripheral targets), and either an oculomotor delayed response (ODR, a task requiring memory-guided saccades after a delay period) or a conditional antisaccade task (a task in which the color of the peripheral target determined whether a saccade toward or away from the target was required). An additional six subjects performed a sequential hand movement task to compare localization of hand-related motor cortex and the frontal eye fields (FEFs) and of the hand- and eye-movement-related regions of the supplementary motor area (SMA). 3. Friston's statistical parametric mapping (SPM) method was used to identify significant changes in rCBF associated with task performance. Because SPM does not take advantage of the anatomic information available in magnetic resonance (MR) scans, each subject's PET scan was registered to that individual's MR scan, after which all PET and MR studies were transformed to conform to a standard reference MR image set. Subtraction images were visually inspected while overlayed on the reference MR scan to which PET images had been aligned, in order to confirm anatomic localization of significant rCBF changes. 4. Compared with visual fixation, performing visually guided saccades led to a significant bilateral activation in FEF, cerebellum, striate cortex, and posterior temporal cortex. Right posterior thalamus activation was also observed. 5. The visually guided saccade task served as the comparison task for the ODR, antisaccade, and conditional antisaccade tasks for identification of task-related changes in rCBF beyond those associated with saccade execution. Performance on the ODR task was associated with a bilateral increase of rCBF in FEFs, SMA, dorsolateral prefrontal cortex (DLPFC), and posterior parietal cortex. The cortical regions of increased regional blood flow during the ODR task also showed increased rCBF during the antisaccade task; however, FEF and SMA activations were significant only in the right hemisphere. These findings closely parallel those of single-cell recording studies with behaving monkeys in indicating that FEF, DLPFC, SMA, and posterior parietal cortex perform computational activity for voluntary purposive saccades. 6. Comparison of PET scans obtained during performance of eye movement and hand movement tasks indicated that peak activations in FEF were located approximately 2 cm lateral and 1 cm anterior to those of hand-related motor cortex. The oculomotor area of SMA, the supplementary eye field (SEF), was located approximately 7-8 mm anterior and superior to the hand-related area of SMA. 7. During performance of antisaccade and ODR tasks, rCBF was significantly lower in ventromedial prefrontal cortex (PFC), along the rectus gyrus, and in ventral anterior cingulate cortex than during the visually guided saccade and fixation tasks. During the antisaccade task, the ventral region of lower rCBF involved medial structures including left ventral striatum and bilateral medial temporal-limbic cortex. During the ODR task, the ventral aspect of the region of lower rCBF extended laterally, rather than medially, to include the temporal poles. The lower blood flow observed in ventromedial PFC during both the antisaccade and ODR tasks, relative to the visually guided saccade and fixation tasks, suggests that modulation of output from ventromedial PFC to limbic cortex and the striatum may play a role in the voluntary control of saccadic eye movements, possibly in the suppression of responses that would interrupt

Comprehensive, human cellular protein databases and their implication for the study of genome organization and function

Comprehensive, computerized databases of cellular protein information derived from the analysis of two-dimensional gels, together with recently developed techniques to microsequence proteins offer a new dimension to the study of genome organization and function. In particular, human protein databases provide an ideal framework in which to focus the human genome sequencing effort.

Computerized, comprehensive databases of cellular and secreted proteins from normal human embryonic lung MRC-5 fibroblasts: identification of transformation and/or proliferation sensitive proteins

Databases of protein information from human embryonal lung fibroblasts (MRC-5) have been established using computer analyzed two-dimensional gel electrophoresis. One thousand four hundred and eighty-two cellular proteins (1060 with isoelectric focusing and 422 with nonequilibrium pH gradient electrophoresis, in the first dimension) ranging in molecular mass between 8 and 234 kDa were separated and numbered. Information entered in the database (in most cases for major proteins) includes: protein name, HeLa protein catalog number, mouse protein catalog number, proteins matched in transformed human epithelial amnion cells (AMA) and peripheral blood mononuclear cells (PBMC), transformation and/or proliferation sensitive proteins, synthesis in quiescent cells, cell cycle regulated proteins, mitochondrial and heat shock proteins, cytoskeletal proteins and proteins whose synthesis is affected by interferons. Additional information entered for a few transformation-sensitive proteins that have been selected for future studies includes levels of synthesis and amounts in fetal human tissues. A total of four hundred and seventy-six [35S]methionine labeled polypeptides (258 isoelectric focusing; 218, nonequilibrium pH gradient electrophoresis) secreted by MRC-5 fibroblasts were separated and recorded (J. E. Celis et al., Leukemia 1987, 1, 707-717). Information entered in this database includes molecular weight and transformation sensitive proteins. These databases, as well as those of epithelial and lymphoid cell proteins (J. E. Celis et al., Leukemia 1988, 9, 561-601), represent the initial stages of a systematic effort to establish comprehensive databases of human protein information. In the long run, these databases are expected to offer a useful framework in which to focus the human genome sequencing effort.

Towards establishing comprehensive databases of cellular proteins from transformed human epithelial amnion cells (AMA) and normal peripheral blood mononuclear cells

Databases of protein information derived from the analysis of two-dimensional gels have been established from transformed human amnion cells (AMA) and peripheral blood mononuclear cells (PBMCs). A total of 1781 [35S]methionine-labeled AMA proteins (1274 IEF, 537 NEPHGE) and a total of 1311 proteins from PBMC (948 IEF, 363 NEPHGE) were resolved and recorded using computerized (PDQ-SCAN and PDQUEST softwares) two-dimensional gel electrophoresis. AMA and PBMC proteins (total, 454: 301 IEF, 153 NEPHGE) were matched both manually and by the computer. Information entered in the AMA database (in most cases for some major proteins) includes: molecular weight, protein name, HeLa protein catalogue number, mouse protein catalogue number, nuclear proteins, phosphorylated proteins, distribution of proteins in Triton X-100 supernatants and cytoskeletons, proliferation- and transformation-sensitive proteins, cell cycle-specific proteins, mitochondrial proteins, proteins matched in normal human embryonal lung MRC-5 fibroblasts and PBMC cells, heat shock proteins, proteins affected by interferons, cytoskeletal proteins, and the presence of antibody against protein in human sera. Additional information has been entered for the cell cycle-regulated and DNA replication protein cyclin (PCNA). Information entered in the PBMC database includes molecular weight and potential markers for sorted populations of lymphocyte subtypes. For those proteins that have been matched to AMA proteins, information contained in some entries may be transferred from the AMA database.

Mode of interaction of polyoxyethyleneglycol detergents with membrane proteins

Binding of dodecyloctaethyleneglycol monoether (C12E3) and purified Triton X-100 to various integral membrane proteins was studied by chromatographic procedures. Binding capacity decreased in the following order: bovine rhodopsin greater than photochemical reaction center greater than sarcoplasmic reticulum Ca2+-ATPase. The detergents were bound in different amounts to the proteins and less than corresponding to the aggregation number of the pure micelles. Appreciable binding of C12E8 to Ca2+-ATPase was observed far below the critical micelle concentration, consistent with interaction of the membrane protein with non-micellar detergent. Model calculations indicate that the detergents cannot combine with the membrane proteins, forming an oblate ring similar to that of pure detergent micelles, such as has been previously proposed for e.g. cytochrome b5 [Robinson and Tanford (1975) Biochemistry, 14, 365-378]. Other arrangements (prolate and monolayer rings), in which all detergent molecules are in contact with the protein, are considered as alternatives for covering the hydrophobic surface of the membrane protein with a continuous layer of detergent.