Comparison of actionable events detected in cancer genomes by whole-genome sequencing, in silico whole-exome and mutation panels

Background

Next-generation sequencing is used in cancer research to identify somatic and germline mutations, which can predict sensitivity or resistance to therapies, and may be a useful tool to reveal drug repurposing opportunities between tumour types. Multigene panels are used in clinical practice for detecting targetable mutations. However, the value of clinical whole-exome sequencing (WES) and whole-genome sequencing (WGS) for cancer care is less defined, specifically as the majority of variants found using these technologies are of uncertain significance.

Patients and methods

We used the Cancer Genome Interpreter and WGS in 726 tumours spanning 10 cancer types to identify drug repurposing opportunities. We compare the ability of WGS to detect actionable variants, tumour mutation burden (TMB) and microsatellite instability (MSI) by using in silico down-sampled data to mimic WES, a comprehensive sequencing panel and a hotspot mutation panel.

Results

We reveal drug repurposing opportunities as numerous biomarkers are shared across many solid tumour types. Comprehensive panels identify the majority of approved actionable mutations, with WGS detecting more candidate actionable mutations for biomarkers currently in clinical trials. Moreover, estimated values for TMB and MSI vary when calculated from WGS, WES and panel data, and are dependent on whether all mutations or only non-synonymous mutations were used. Our results suggest that TMB and MSI thresholds should not only be tumour-dependent, but also be sequencing platform-dependent.

Conclusions

There is a large opportunity to repurpose cancer drugs, and these data suggest that comprehensive sequencing is an invaluable source of information to guide clinical decisions by facilitating precision medicine and may provide a wealth of information for future studies. Furthermore, the sequencing and analysis approach used to estimate TMB may have clinical implications if a hard threshold is used to indicate which patients may respond to immunotherapy.

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Genome analysis revealed that treatment biomarkers are shared across solid tumours, highlighting repurposing opportunities.

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Comprehensive panels detect most known biomarkers; however, WGS detects more biomarkers for treatments in clinical trials.

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TMB is well correlated between sequencing methods, but absolute values vary and are dependent on mutation types considered.

E-cigarettes and health risks: more to the flavor than just the name

The growing interest in regulating flavored E-liquids must incorporate understanding of the "flavoring profile" of each E-liquid-which flavorings (flavoring chemicals) are present and at what concentrations not just focusing on the flavor on the label. We investigated the flavoring profile of 10 different flavored E-liquids. We assessed bronchial epithelial cell viability and apoptosis, phagocytosis of bacteria and apoptotic cells by macrophages after exposure to E-cigarette vapor extract (EVE). We validated our data in normal human bronchial epithelial cells (NHBE) and alveolar macrophages (AM) from healthy donors. We also assessed cytokine release and validated in the saliva from E-cigarette users. Increased necrosis/apoptosis (16.1-64.5% apoptosis) in 16HBE cells was flavor dependent, and NHBEs showed an increased susceptibility to flavors. In THP-1 differentiated macrophages phagocytosis was also flavor dependent, with AM also showing increased susceptibility to flavors. Further, Banana and Chocolate were shown to reduce surface expression of phagocytic target recognition receptors on alveolar macrophages. Banana and Chocolate increased IL-8 secretion by NHBE, whereas all 4 flavors reduced AM IL-1β secretion, which was also reduced in the saliva of E-cigarette users compared with healthy controls. Flavorant profiles of E-liquids varied from simple 2 compound mixtures to complex mixtures containing over a dozen flavorants. E-liquids with high benzene content, complex flavoring profiles, high chemical concentration had the greatest impacts. The Flavorant profile of E-liquids is key to disruption of the airway status quo by increasing bronchial epithelial cell apoptosis, causing alveolar macrophage phagocytic dysfunction, and altering airway cytokines.

Reducing Inappropriate Overutilization of the Massive Transfusion Protocol

Introduction/Objective

Massive transfusion protocols (MTPs) make it possible to deliver blood products to exsanguinating patients in an efficient, sustained, and immediate manner. However, overutilization of MTPs continues to remain a significant problem for hospital blood banks. The study aims to address the characteristics of possibly inappropriate MTP activations during the first phase (cooler) at a level 1 trauma academic medical center.

Methods

This was a retrospective review of 328 phase 1 MTPs out of 696 total MTPs performed during a two-year period (Jan 1, 2017 and Dec 31, 2018) and divided into three categories: trauma, non-trauma surgery, and medicine services. We assumed that a possibly inappropriate MTP for trauma cases would show an Assessment of Blood Component (ABC) score of 1 or less and physicians used clinical discretion. For possibly inappropriate MTP non- trauma surgical and medicine cases, we devised a new system where we looked at only whether the blood pressure was equal to or less than 90 mm Hg and/or the pulse was greater than or equal to 120 beats per minute. If there was a score of 0 where there were neither vital sign criteria, then the MTP was considered possibly inappropriate.

Results

For trauma service, there were 43/168 (25.6%) cases that had an ABC score of 0, 49/168 (29.2%) cases that had an ABC score of 1, 53/168 (31.5%) cases that had an ABC score of 2, 21/168 (12.5%) cases that had an ABC score of 3, and only 2/168 (1.2%) case that had an ABC score of 4. Non-trauma surgery service had 31/51 (60.8%) cases with a new score of 0, 20/51 (39.2%) cases with a new score of 1, and 0/51 (0%) cases with a new score of 2. Medicine services had 57/109 (52.3%) patients with a new score of 0, 47/109 (43.1%) patients with a new score of 1, and 5/109 (4.6%) patients with a new score of 2. Non-trauma surgery service had the greatest possibly inappropriate MTP activations [31/51 cases (60.8%)], followed by trauma [92/168 (54.8%) cases] and medicine [57/109 (52.3%) cases].

Conclusion

Our study shows greater overutilization with MTPs using clinical judgment than with using the ABC criteria. Non-trauma surgery service had the greatest number of possibly inappropriate MTP activations at our hospital without having a significantly abnormal pulse or blood pressure. While ABC criteria is already liberal for activating an MTP, physician discretion appears to be more liberal in activating a possibly inappropriate MTP.

Bronchiolitis obliterans syndrome is associated with increased p-glycoprotein expression and loss of glucocorticoid receptor from steroid-resistant proinflammatory CD8+ T cells

Immunosuppressive therapy fails to suppress the production of proinflammatory cytokines, particularly by CD8+ T cells, in stable lung transplant recipients and those undergoing chronic rejection, suggesting that some patients may become relatively resistant to immunosuppressants such as glucocorticoids (GC). We have shown loss of GC receptor (GCR) from the CD8+ cells, and we hypothesized that the drug membrane efflux pump, p-glycoprotein-1 (Pgp), may also be involved in lymphocyte steroid resistance following lung transplant. Pgp/GCR expression and interferon (IFN)-γ/tumour necrosis factor (TNF)-α proinflammatory cytokine production was measured in blood lymphocytes from 15 stable lung transplant patients, 10 patients with bronchiolitis obliterans syndrome (BOS) and 10 healthy aged-matched controls (± prednisolone ± Pgp inhibitor, cyclosporin A ± GCR activator, Compound A) using flow cytometry. Both Pgp+ and Pgp- lymphocyte subsets from all subjects produced IFN-γ/TNF-α proinflammatory cytokines. Pgp expression was increased in CD8+ Pgp+ T cells and correlated with IFN-γ/TNF-α expression and BOS grade. Reduced GCR was observed in CD8+ Pgp- T, natural killer (NK) T-like and NK cells from stable patients compared with controls, and reduced further in CD8+ Pgp- T cells in BOS. The addition of 2·5 ng/ml cyclosporin A and 1 µM prednisolone inhibit IFN-γ/TNF-α production significantly by CD8+ Pgp+ T cells from BOS patients. The addition of 10 µM Compound A and 1 µM prednisolone inhibit IFN-γ/TNF-α production significantly by CD8+ Pgp- T cells from BOS patients. BOS is associated with increased Pgp expression and loss of GCR from steroid-resistant proinflammatory CD8+ T cells. Treatments that inhibit Pgp and up-regulate GCR in CD8+ T cells may improve graft survival.

Appearance of reassortant European avian-origin H1 influenza A viruses of swine in Vietnam

Three subtypes-H1N1, H1N2 and H3N2-of influenza A viruses of swine (IAVs-S) are currently endemic in swine worldwide, but there is considerable genotypic diversity among each subtype and limited geographical distribution. Through IAVs-S monitoring in Vietnam, two H1N2 influenza A viruses were isolated from healthy pigs in Ba Ria-Vung Tau Province, Southern Vietnam, on 2 December 2016. BLAST and phylogenetic analyses revealed that their HA and NA genes were derived from those of European avian-like H1N2 IAVs-S that contained avian-origin H1 and human-like N2 genes, and were particularly closely related to those of IAVs-S circulating in the Netherlands, Germany or Denmark. In addition, the internal genes of these Vietnamese isolates were derived from human A(H1N1)pdm09 viruses, suggesting that the Vietnamese H1N2 IAVs-S are reassortants between European H1N2 IAVs-S and human A(H1N1)pdm09v. The appearance of European avian-like H1N2 IAVs-S in Vietnam marks their first transmission outside Europe. Our results and statistical analyses of the number of live pigs imported into Vietnam suggest that the European avian-like H1N2 IAVs-S may have been introduced into Vietnam with their hosts through international trade. These findings highlight the importance of quarantining imported pigs to impede the introduction of new IAVs-S.

A majority rule approach for region-of-interest-guided streamline fiber tractography

Hand-drawn gray matter regions of interest (ROI) are often used to guide the estimation of white matter tractography, obtained from diffusion-weighted magnetic resonance imaging (DWI), in healthy and in patient populations. However, such ROIs are vulnerable to rater bias of the individual segmenting the ROIs, scan variability, and individual differences in neuroanatomy. In this report, a "majority rule" approach is introduced for ROI segmentation used to guide streamline tractography in white matter structures. DWI of one healthy participant was acquired in ten separate sessions using a 3 T scanner over the course of a month. Four raters identified ROIs within the left hemisphere [Cerebral Peduncle (CPED); Internal Capsule (IC); Hand Portion of the Motor Cortex, or Hand Bump, (HB)] using a group-established standard operating procedure for ROI definition to guide the estimation of streamline tracts within the corticospinal tract (CST). Each rater traced the ROIs twice for each scan session. The overlap of each rater's two ROIs was used to define a representative ROI for each rater. These ROIs were combined to create a "majority rules" ROI, in which the rule requires that each voxel is selected by at least three of four raters. Reproducibility for ROIs and CST segmentations were analyzed with the Dice Similarity Coefficient (DSC). Intra-rater reliability for each ROI was high (DSCs ≥ 0.83). Inter-rater reliability was moderate to adequate (DSC range 0.54-0.75; lowest for IC). Using intersected majority rules ROIs, the resulting CST showed improved overlap (DSC = 0.82) in the estimated streamline tracks for the ten sessions. Despite high intra-rater reliability, there was lower inter-rater reliability consistent with the expectation of rater bias. Employing the majority rules method improved reliability in the overlap of the CST.

An Integrative Analysis of Foot-and-Mouth Disease Virus Carriers in Vietnam Achieved Through Targeted Surveillance and Molecular Epidemiology

Foot-and-mouth disease (FMD) is a major constraint to transboundary trade in animal products, yet much of its natural ecology and epidemiology in endemic regions is still poorly understood. To address this gap, a multidisciplinary, molecular and conventional epidemiological approach was applied to an investigation of endemic FMD in Vietnam. Within the study space, it was found that 22.3% of sampled ruminants had previously been infected with FMD virus (FMDV), of which 10.8% were persistent, asymptomatic carriers (2.4% of the total population). Descriptive data collected from targeted surveillance and a farm questionnaire showed a significantly lower prevalence of FMDV infection for dairy farms. In contrast, farms of intermediate size and/or history of infection in 2010 were at increased risk of FMD exposure. At the individual animal level, buffalo had the highest exposure risk (over cattle), and there was spatial heterogeneity in exposure risk at the commune level. Conversely, carrier prevalence was higher for beef cattle, suggesting lower susceptibility of buffalo to persistent FMDV infection. To characterize virus strains currently circulating in Vietnam, partial FMDV genomic (VP1) sequences from carrier animals collected between 2012 and 2013 (N = 27) and from FMDV outbreaks between 2009 and 2013 (N = 79) were compared by phylogenetic analysis. Sequence analysis suggested that within the study period, there were two apparent novel introductions of serotype A viruses and that the dominant lineage of serotype O in Vietnam shifted from SEA/Mya-98 to ME-SA/PanAsia. FMDV strains shared close ancestors with FMDV from other South-East Asian countries indicating substantial transboundary movement of the predominant circulating strains. Close genetic relationships were observed between carrier and outbreak viruses, which may suggest that asymptomatic carriers of FMDV contribute to regional disease persistence. Multiple viral sequences obtained from carrier cattle over a 1-year period had considerable within-animal genetic variation, indicating within-host virus evolution.

Phase II clinical trial of pasireotide long-acting repeatable in patients with metastatic neuroendocrine tumors

Pasireotide long-acting repeatable (LAR) is a novel somatostatin analog (SSA) with avid binding affinity to somatostatin receptor subtypes 1, 2, 3 (SSTR1,2,3) and 5 (SSTR5). Results from preclinical studies indicate that pasireotide can inhibit neuroendocrine tumor (NET) growth more robustly than octreotide in vitro. This open-label, phase II study assessed the clinical activity of pasireotide in treatment-naïve patients with metastatic grade 1 or 2 NETs. Patients with metastatic pancreatic and extra-pancreatic NETs were treated with pasireotide LAR (60 mg every 4 weeks). Previous systemic therapy, including octreotide and lanreotide, was not permitted. Tumor assessments were performed every 3 months using Response Evaluation Criteria in Solid Tumors (RECIST) criteria. The primary endpoint was progression-free survival (PFS). The secondary endpoints included overall survival (OS), overall radiographic response rate (ORR), and safety. Twenty-nine patients were treated with pasireotide LAR (60 mg every 4 weeks) and 28 were evaluable for response. The median PFS was 11 months. The most favorable effect was observed in patients with low hepatic tumor burden, normal baseline chromogranin A, and high tumoral SSTR5 expression. Median OS has not been reached; the 30-month OS rate was 70%. The best radiographic response was partial response in one patient (4%), stable disease in 17 patients (60%), and progressive disease in ten patients (36%). Although grade 3/4 toxicities were rare, pasireotide LAR treatment was associated with a 79% rate of hyperglycemia including 14% grade 3 hyperglycemia. Although pasireotide appears to be an effective antiproliferative agent in the treatment of advanced NETs, the high incidence of hyperglycemia raises concerns regarding its suitability as a first-line systemic agent in unselected patients. SSTR5 expression is a potentially predictive biomarker for response.

Mapping cerebral blood flow changes during auditory-cued conditioned fear in the nontethered, nonrestrained rat

Conditioned fear (CF) is one of the most frequently used behavioral paradigms; however, little work has mapped changes in cerebral perfusion during CF in the rat-the species which has dominated CF research. Adult rats carrying an implanted minipump were exposed to a tone (controls, n = 8) or a tone conditioned in association with footshocks (CS group, n = 9). During reexposure to the tone 24 h later, animals were injected intravenously by remote activation with [14C]-iodoantipyrine using the pump. Significant group differences in regional CBF-related tissue radioactivity (CBF-TR) were determined by region-of-interest analysis of brain autoradiographs, as well as in the reconstructed, three-dimensional brain by statistical parametric mapping (SPM). CS animals demonstrated significantly greater, fear-enhanced increases in CBF-TR in auditory cortex than controls. The lateral amygdala was activated, whereas the basolateral/basomedial and central amygdala were deactivated. In the hippocampus and medial prefrontal cortex, CBF-TR increased significantly ventrally but not dorsally. Significant activations were noted in medial striatum and the thalamic midline and intralaminar nuclei. However, the ventrolateral/dorsolateral striatum and its afferents from motor and somatosensory cortex were deactivated, consistent with the behavioral immobility seen during CF. Significant activations were also noted in the lateral septum, periaqueductal gray, and deep mesencephalic nucleus/tegmental tract. Our results show that auditory stimuli endowed with aversive properties through conditioning result in significant redistribution of cerebral perfusion. SPM is a useful tool in the brain mapping of complex rodent behaviors, in particular the changes in activation patterns in limbic, thalamic, motor, and cortical circuits during CF.

Impact of endoscopic ultrasound combined with fine-needle aspiration biopsy in the management of esophageal cancer

BACKGROUND AND STUDY AIMS

Endoscopic ultrasound (EUS) in combination with fine-needle aspiration biopsy (FNA) is a highly accurate method for the preoperative staging of esophageal cancer. Its impact on medical decision-making and the cost of care is unknown. This prospective case series was undertaken in order to determine the impact of EUS in combination with FNA on patients' choice of therapy and on the cost of care.

PATIENTS AND METHODS

Sixty consecutive patients with esophageal cancer, referred for preoperative EUS staging in a large tertiary-care academic medical center, were enrolled. The accuracy of EUS, the impact of EUS-based staging on the patients' choice of therapy, and costs were studied.

RESULTS

The accuracy rates for EUS combined with FNA in tumor and lymph-node staging were 83 % and 89 %, respectively. Twenty-five patients (42 %) had EUS stage I and II and were candidates for curative surgery. Twenty-eight patients (47 %) had stage III, and seven (12 %) had stage IV. All patients with stage I had surgery, while all patients with stage IV had medical therapy. The majority (62 %) of patients with stage II had surgery, while only a minority (25 %) of patients with stage III had surgery. Thirty-six patients (60 %) underwent medical therapy. Patients' medical decisions in favor of surgical or medical therapy correlated strongly with the results of their EUS staging ( P = 0.005), but not with age, sex, or referring physicians (surgeons vs. nonsurgeons). EUS-guided therapy potentially decreased the cost of care by $ 740 424 ($ 12 340/patient) by reducing the number of thoracotomies.

CONCLUSIONS

Patients' decisions regarding therapy correlated with their overall tumor staging, suggesting that the information provided by EUS played a significant role in patients' decision-making. The use of EUS in combination with FNA reduces the cost of managing patients with esophageal cancer.

Cytologic diagnosis of gastrointestinal stromal tumors of the stomach by endoscopic ultrasound-guided fine-needle aspiration biopsy: cytomorphologic and immunohistochemical study of 12 cases

Gastrointestinal stromal tumor (GIST) is an uncommon tumor, which was usually diagnosed by endoscopic biopsy or surgical resection. This study evaluated the efficacy and accuracy of endoscopic ultrasound (EUS) -guided fine-needle aspiration (FNA) biopsy in the diagnosis of GIST and reported its cytomorphologic features. Twelve patients with gastric GIST were diagnosed through EUS-guided FNA. Immediate on-site evaluation and cytologic diagnoses were given in nine cases (75.0%) with an average of three passes. Cell blocks provided diagnostic material in three cases (25.0%). Spindle cells were present in the cytologic material in all cases. Two patients had subsequent surgical resections. Immunohistochemical (IHC) studies performed in cell blocks and two surgical specimens all supported the original diagnoses. In the two cases with surgical resections, IHC results in cell blocks were similar to that in the resected specimens. This study demonstrated that when combining smears and cell blocks, EUS-guided FNA is accurate and efficient in the diagnosis of GIST. IHC reactivity in cell blocks correlated with that of the main tumors.

EUS in the detection of ascites and EUS-guided paracentesis

BACKGROUND

The utility of EUS was evaluated for detection of ascites and EUS-guided FNA of ascites in patients undergoing EUS for diagnosis and staging of GI malignancies.

METHODS

A series (from March 1994 to October 1997) of 571 consecutive patients who underwent upper EUS for various indications was retrospectively reviewed. Follow-up clinical information was obtained from referring physicians, subsequent CT, and telephone interviews.

RESULTS

Eighty-five patients (15% of series) were found to have ascites by EUS. Six did not have CT before EUS. Pre-EUS CT identified ascites in only 14 (18%) of the 79 patients who had pre-EUS CT. Of the patients in whom CT was negative for abdominal fluid (n = 65) and who had clinical follow-up, 13 of 58 (22%) subsequently had ascites develop that were detected by CT or physical examination. Overall, 31 of the 85 patients underwent EUS-guided FNA paracentesis; the mean volume obtained was 7.9 mL (range 1-40 mL). In 5 patients, malignant ascites was diagnosed by EUS-guided FNA; in these patients surgery was avoided.

CONCLUSIONS

EUS is more sensitive than CT in detecting small amounts of ascites. A significant number (22%) of patients who had ascites by EUS subsequently had ascites develop that was detectable by CT or physical examination. EUS-guided paracentesis appears to be safe and effective and can identify malignant ascites.

Identification of novel HLA-A2-restricted human immunodeficiency virus type 1-specific cytotoxic T-lymphocyte epitopes predicted by the HLA-A2 supertype peptide-binding motif

Virus-specific cytotoxic T-lymphocyte (CTL) responses are critical in the control of human immunodeficiency virus type 1 (HIV-1) infection and will play an important part in therapeutic and prophylactic HIV-1 vaccines. The identification of virus-specific epitopes that are efficiently recognized by CTL is the first step in the development of future vaccines. Here we describe the immunological characterization of a number of novel HIV-1-specific, HLA-A2-restricted CTL epitopes that share a high degree of conservation within HIV-1 and a strong binding to different alleles of the HLA-A2 superfamily. These novel epitopes include the first reported CTL epitope in the Vpr protein. Two of the novel epitopes were immunodominant among the HLA-A2-restricted CTL responses of individuals with acute and chronic HIV-1 infection. The novel CTL epitopes identified here should be included in future vaccines designed to induce HIV-1-specific CTL responses restricted by the HLA-A2 superfamily and will be important to assess in immunogenicity studies in infected persons and in uninfected recipients of candidate HIV-1 vaccines.

CD1d on myeloid dendritic cells stimulates cytokine secretion from and cytolytic activity of V alpha 24J alpha Q T cells: a feedback mechanism for immune regulation

The precise immunologic functions of CD1d-restricted, CD161+ AV24AJ18 (Valpha24JalphaQ) T cells are not well defined, although production of IL-4 has been suggested as important for priming Th2 responses. However, activation of human Valpha24JalphaQ T cell clones by anti-CD3 resulted in the secretion of multiple cytokines notably important for the recruitment and differentiation of myeloid dendritic cells. Specific activation of Valpha24JalphaQ T cells was CD1d restricted. Expression of CD1d was found on monocyte-derived dendritic cells in vitro, and immunohistochemical staining directly revealed CD1d preferentially expressed on dendritic cells in the paracortical T cell zones of lymph nodes. Moreover, myeloid dendritic cells both activated Valpha24JalphaQ T cells and were susceptible to lysis by these same regulatory T cells. Because myeloid dendritic cells are a major source of IL-12 and control Th1 cell differentiation, their elimination by lysis is a mechanism for limiting the generation of Th1 cells and thus regulating Th1/Th2 responses.

Impaired CTL recognition of cells latently infected with Kaposi's sarcoma-associated herpes virus

Kaposi's sarcoma-associated herpes virus (KSHV) is a recently identified human gamma2-herpesvirus associated with Kaposi's sarcoma, primary effusion lymphoma, and Castleman's disease. We reasoned that CTL responses may provide host defense against this virus, and consequently, KSHV may have evolved strategies to evade the CTL-mediated immune surveillance. In this study six B cell lines latently infected with KSHV were found to express reduced levels of HLA class I surface molecules compared with B cell lines transformed by the related gamma-herpesvirus EBV. KSHV-infected cells also required higher concentrations of soluble peptides to induce efficient CTL-mediated lysis than control cell lines and were unable to process and/or present intracellularly expressed Ag. Incubation of the KSHV-infected cell lines with high concentrations of soluble HLA class I binding peptides did not restore the deficient HLA class I surface expression. To assess the underlying mechanisms of these phenomena, TAP-1 and TAP-2 gene expression was analyzed. While no attenuation in TAP-2 expression was observed, TAP-1 expression was significantly reduced in all KSHV cell lines compared with that in controls. These results indicate that KSHV can modulate HLA class I-restricted Ag presentation to CTL, which may allow latently infected cells to escape CTL recognition and persist in the infected host.

Inhibition of human immunodeficiency virus type 1 replication in primary CD4(+) T lymphocytes, monocytes, and dendritic cells by cytotoxic T lymphocytes

We demonstrate that human immunodeficiency virus type 1 (HIV-1)-specific CD8(+) cytotoxic T lymphocytes (CTL) suppress HIV-1 replication in primary lymphocytes, monocytes, and dendritic cells individually. Viral inhibition is significantly diminished in lymphocyte-dendritic cell clusters, suggesting that these clusters in vivo could be sites where viral replication is more difficult to control by CTL.

Phase I clinical trial of allogeneic mixed lymphocyte culture (cytoimplant) delivered by endoscopic ultrasound-guided fine-needle injection in patients with advanced pancreatic carcinoma

BACKGROUND

To the authors' knowledge, there are no other published clinical studies that have employed either systemic or local biologic response modifiers in the treatment of patients with pancreatic carcinoma. The purpose of this study was to determine the feasibility and safety of allogeneic mixed lymphocyte culture (cytoimplant) delivered by endoscopic ultrasound (EUS)-guided fine-needle injection (FNI) in patients with advanced pancreatic carcinoma.

METHODS

Eight patients with unresectable adenocarcinoma of the pancreas were enrolled: 4 patients in Stage II, 3 in Stage III, and 1 in Stage IV. Cytoimplants were delivered locally into the tumor using a novel EUS-guided FNI technique. Escalating doses of 3, 6, or 9 billion cells were implanted into the pancreatic tumor by a single EUS-guided FNI. Toxicity (modified National Cancer Institute criteria) was assessed at Day 1, Week 1, and Months 1 and 3. Clinical endpoints included Karnofsky performance status (KPS), CA 19-9, tumor response (computed tomography and/or EUS), and survival with follow-up examinations and imaging tests on months 3, 6, 9, 12, and 24.

RESULTS

There were no bone marrow, hemorrhagic, infectious, renal, cardiac, or pulmonary toxicities. There were 3 transient Grade 3 gastrointestinal toxicities, and 3 patients had transient episodes of hyperbilirubinemia that were reversed by replacement of biliary stents. Seven of 8 patients (86%) experienced low grade fever that responded to acetaminophen, and all fever was resolved within the first 4 weeks. There were no procedure-related complications. There were 2 partial responses and 1 minor response, with a median survival of 13.2 months.

CONCLUSIONS

A single injection of cytoimplant immunotherapy by EUS-guided FNI appears to be feasible and is not associated with substantial toxicity.

Phase I clinical trial of allogeneic mixed lymphocyte culture (cytoimplant) delivered by endoscopic ultrasound-guided fine-needle injection in patients with advanced pancreatic carcinoma

BACKGROUND

To the authors' knowledge, there are no other published clinical studies that have employed either systemic or local biologic response modifiers in the treatment of patients with pancreatic carcinoma. The purpose of this study was to determine the feasibility and safety of allogeneic mixed lymphocyte culture (cytoimplant) delivered by endoscopic ultrasound (EUS)-guided fine-needle injection (FNI) in patients with advanced pancreatic carcinoma.

METHODS

Eight patients with unresectable adenocarcinoma of the pancreas were enrolled: 4 patients in Stage II, 3 in Stage III, and 1 in Stage IV. Cytoimplants were delivered locally into the tumor using a novel EUS-guided FNI technique. Escalating doses of 3, 6, or 9 billion cells were implanted into the pancreatic tumor by a single EUS-guided FNI. Toxicity (modified National Cancer Institute criteria) was assessed at Day 1, Week 1, and Months 1 and 3. Clinical endpoints included Karnofsky performance status (KPS), CA 19-9, tumor response (computed tomography and/or EUS), and survival with follow-up examinations and imaging tests on months 3, 6, 9, 12, and 24.

RESULTS

There were no bone marrow, hemorrhagic, infectious, renal, cardiac, or pulmonary toxicities. There were 3 transient Grade 3 gastrointestinal toxicities, and 3 patients had transient episodes of hyperbilirubinemia that were reversed by replacement of biliary stents. Seven of 8 patients (86%) experienced low grade fever that responded to acetaminophen, and all fever was resolved within the first 4 weeks. There were no procedure-related complications. There were 2 partial responses and 1 minor response, with a median survival of 13.2 months.

CONCLUSIONS

A single injection of cytoimplant immunotherapy by EUS-guided FNI appears to be feasible and is not associated with substantial toxicity.

Phase I clinical trial of allogeneic mixed lymphocyte culture (cytoimplant) delivered by endoscopic ultrasound-guided fine-needle injection in patients with advanced pancreatic carcinoma

BACKGROUND

To the authors' knowledge, there are no other published clinical studies that have employed either systemic or local biologic response modifiers in the treatment of patients with pancreatic carcinoma. The purpose of this study was to determine the feasibility and safety of allogeneic mixed lymphocyte culture (cytoimplant) delivered by endoscopic ultrasound (EUS)-guided fine-needle injection (FNI) in patients with advanced pancreatic carcinoma.

METHODS

Eight patients with unresectable adenocarcinoma of the pancreas were enrolled: 4 patients in Stage II, 3 in Stage III, and 1 in Stage IV. Cytoimplants were delivered locally into the tumor using a novel EUS-guided FNI technique. Escalating doses of 3, 6, or 9 billion cells were implanted into the pancreatic tumor by a single EUS-guided FNI. Toxicity (modified National Cancer Institute criteria) was assessed at Day 1, Week 1, and Months 1 and 3. Clinical endpoints included Karnofsky performance status (KPS), CA 19-9, tumor response (computed tomography and/or EUS), and survival with follow-up examinations and imaging tests on months 3, 6, 9, 12, and 24.

RESULTS

There were no bone marrow, hemorrhagic, infectious, renal, cardiac, or pulmonary toxicities. There were 3 transient Grade 3 gastrointestinal toxicities, and 3 patients had transient episodes of hyperbilirubinemia that were reversed by replacement of biliary stents. Seven of 8 patients (86%) experienced low grade fever that responded to acetaminophen, and all fever was resolved within the first 4 weeks. There were no procedure-related complications. There were 2 partial responses and 1 minor response, with a median survival of 13.2 months.

CONCLUSIONS

A single injection of cytoimplant immunotherapy by EUS-guided FNI appears to be feasible and is not associated with substantial toxicity.

Phase I clinical trial of allogeneic mixed lymphocyte culture (cytoimplant) delivered by endoscopic ultrasound-guided fine-needle injection in patients with advanced pancreatic carcinoma

BACKGROUND

To the authors' knowledge, there are no other published clinical studies that have employed either systemic or local biologic response modifiers in the treatment of patients with pancreatic carcinoma. The purpose of this study was to determine the feasibility and safety of allogeneic mixed lymphocyte culture (cytoimplant) delivered by endoscopic ultrasound (EUS)-guided fine-needle injection (FNI) in patients with advanced pancreatic carcinoma.

METHODS

Eight patients with unresectable adenocarcinoma of the pancreas were enrolled: 4 patients in Stage II, 3 in Stage III, and 1 in Stage IV. Cytoimplants were delivered locally into the tumor using a novel EUS-guided FNI technique. Escalating doses of 3, 6, or 9 billion cells were implanted into the pancreatic tumor by a single EUS-guided FNI. Toxicity (modified National Cancer Institute criteria) was assessed at Day 1, Week 1, and Months 1 and 3. Clinical endpoints included Karnofsky performance status (KPS), CA 19-9, tumor response (computed tomography and/or EUS), and survival with follow-up examinations and imaging tests on months 3, 6, 9, 12, and 24.

RESULTS

There were no bone marrow, hemorrhagic, infectious, renal, cardiac, or pulmonary toxicities. There were 3 transient Grade 3 gastrointestinal toxicities, and 3 patients had transient episodes of hyperbilirubinemia that were reversed by replacement of biliary stents. Seven of 8 patients (86%) experienced low grade fever that responded to acetaminophen, and all fever was resolved within the first 4 weeks. There were no procedure-related complications. There were 2 partial responses and 1 minor response, with a median survival of 13.2 months.

CONCLUSIONS

A single injection of cytoimplant immunotherapy by EUS-guided FNI appears to be feasible and is not associated with substantial toxicity.

Inverting enantioselectivity by directed evolution of hydantoinase for improved production of L-methionine

Using directed evolution, we have improved the hydantoinase process for production of L-methionine (L-met) in Escherichia coli. This was accomplished by inverting the enantioselectivity and increasing the total activity of a key enzyme in a whole-cell catalyst. The selectivity of all known hydantoinases for D-5-(2-methylthioethyl)hydantoin (D-MTEH) over the L-enantiomer leads to the accumulation of intermediates and reduced productivity for the L-amino acid. We used random mutagenesis, saturation mutagenesis, and screening to convert the D-selective hydantoinase from Arthrobacter sp. DSM 9771 into an L-selective enzyme and increased its total activity fivefold. Whole E. coli cells expressing the evolved L-hydantoinase, an L-N-carbamoylase, and a hydantoin racemase produced 91 mM L-met from 100 mM D,L-MTEH in less than 2 h. The improved hydantoinase increased productivity fivefold for >90% conversion of the substrate. The accumulation of the unwanted intermediate D-carbamoyl-methionine was reduced fourfold compared to cells with the wild-type pathway. Highly D-selective hydantoinase mutants were also discovered. Enantioselective enzymes rapidly optimized by directed evolution and introduced into multienzyme pathways may lead to improved whole-cell catalysts for efficient production of chiral compounds.

A pharmacokinetic and pharmacodynamic study of artesunate for vivax malaria

To investigate the pharmacokinetic and pharmacodynamic properties of artesunate (ARTS) and its active metabolite dihydroartemisinin (DHA) in Plasmodium vivax infections, 12 male Vietnamese adults with slide-positive vivax malaria received either intravenous ARTS (120 mg; group 1) or oral ARTS (100 mg; group 2) with the alternative preparation given 8 hr later in a randomized, open, cross-over study. Following intravenous injection, ARTS had a peak plasma drug concentration (Cmax) of 35.6 microM (13.7 mg/L), an elimination half-life (t1/2) of 2.2 min, a clearance (CL) of 3.0 L/hr/kg, and a volume of distribution (V) of 0.16 L/kg. Dihydroartemisinin had a Cmax of 7.7 microM (2.2 mg/L), a tmax of 8 min, a t1/2 of 37 min, an apparent CL of 1.1 L/hr/kg, and an apparent V of 0.9 L/kg. Following oral ARTS, the mean relative bioavailability of DHA was 85%, the Cmax was 3.0 microM (0.85 mg/L), the tmax was 75 min, and t1/2 was 40 min. The mean time to 50% reduction in the parasite count (PCT50) and median fever clearance time were 3 hr and 16 hr, respectively. Following intravenous ARTS (group 1), the PCT50 for total parasites, rings, trophozoites, and gametocytes was 3.3 hr, 3.2 hr, 4.0 hr, and 3.6 hr, respectively. This study confirms that ARTS is effective against P. vivax, with rapid clearance of sexual and asexual forms of the parasite. Artesunate is a suitable initial treatment for vivax malaria, or when the plasmodial species cannot be reliably identified.

A polymerase chain reaction assay for the detection of Leptospira spp. in bovine semen

A rapid and specific method for the detection of pathogenic Leptospira spp. in bovine semen using the polymerase chain reaction (PCR) is described. The primers used were derived from an EcoR1/BamH1 fragment that hybridized strongly to chromosomal DNA from the hardjobovis serovar. Three different extraction methods were evaluated in this study: phenol-chloroform extraction method, proteinase K (PK) in 1% SDS, followed by phenol-chloroform, and phenol-chloroform followed by 1% cetyltrimethylammonium bromide (CTAB). A PCR product of approximately 500 base pairs (bp) in length was obtained when DNA from pure Leptospira culture was used as a template for PCR, regardless of the DNA extraction method used. The product was consistent with that predicted from the gene sequence. However, in semen seeded in vitro, as well as in semen from infected bulls, a PCR product was obtained only when the leptospiral DNA was extracted from the specimen using the CTAB method. In contrast, other methods used for DNA extraction did not generate suitable templates for the PCR procedure. This is the first PCR protocol developed to detect Leptospira in bovine semen. The PCR protocol provided a direct and unequivocal demonstration that Leptospira can be detected in semen of infected animals. The CTAB method was also used successfully in detecting Leptospira in the urine of infected animals. The PCR procedure was shown to be more sensitive than either the fluorescent antibody test (FAT) or culture for detecting the organism in urine.

Anatomic distribution of metastases in the vertebral body and modes of hematogenous spread

STUDY DESIGN

A retrospective review of the magnetic resonance spine examinations of 49 patients with metastatic bone disease to the spine was performed.

OBJECTIVES

To determine whether the pattern of metastatic distribution in the spine correlates with the type of primary tumor and theoretical mode of hematogenous spread by arterial or venous routes.

SUMMARY OF BACKGROUND DATA

In 1940, Batson theorized a venous plexus route by which tumors spread to the spine from pelvic tumors such as prostatic carcinoma. It this theory is true, the venous vascular anatomy of the spine would result in metastases being deposited in the central or posterior vertebral body, whereas arterial deposits would occur near the end-plates.

METHODS

Each vertebral body was divided into 27 equal cells in the magnetic resonance images; the central and posterior cells in the midsagittal view were defined as central, and the other cells were defined as peripheral. The primary tumor was assigned to either the arterial or venous group based on Batson's proposed mode of spread. The average number of lesions per involved vertebral body in the central and peripheral regions was calculated.

RESULTS

There was no statistically significant correlation between tumors with proposed arterial/venous routes of metastasis and central/peripheral location of metastatic deposits.

CONCLUSION

The mechanism by which tumors spread to the vertebral body may not be via a pure arterial or venous route. Other mechanisms such as tissue specificity, cascade system, and closed loop circulation system may be involved.

Rapid detection of bovine herpesvirus 1 in the semen of infected bulls by a nested polymerase chain reaction assay

A nested polymerase chain reaction (PCR) assay was developed for the detection of bovine herpesvirus 1 (BHV-1) in bovine semen and compared with the virus isolation method. When extended semen, commonly used in the bovine artificial insemination industry, was inoculated with BHV-1, the PCR assay detected BHV-1 DNA in semen inoculated at 0.25-2.5 TCID50 per 0.5 mL. In contrast, the lower limit of detection for virus isolation was 250 TCID50 of BHV-1 inoculated in 0.5 mL of extended semen. These methods were also used to detect BHV-1 in the semen of four bulls which were experimentally infected with BHV-1. All infected bulls demonstrated balanitis at 3 d post-inoculation (DPI) and severe balanoposthitis at 4 DPI. BHV-1 was detected in raw semen by virus isolation and PCR at 2 DPI, before balanitis was evident. For virus isolation, the last day that BHV-1 was detected during primary infection was 7 DPI for two bulls and 9 and 11 DPI for the other two bulls. In contrast, PCR detected BHV-1 in the bulls' semen until 14 or 18 DPI. For individual animals, PCR detected BHV-1 during primary infection for at least 1-10 d longer than virus isolation. Reactivation of BHV-1 from latency without the presence of visible lesions was promoted twice by two series of 5 d dexamethasone injections. For the first series of dexamethasone treatments, a positive virus isolation result was obtained on the 5th d of treatment for only one bull. In contrast, two bulls demonstrated evidence of viral reactivation on this day by PCR. All bulls shed BHV-1 in semen on d 4 after dexamethasone treatment, as evidenced by positive virus isolation and PCR results. One bull was still PCR positive 13 d later. For the second series of dexamethasone treatments, a small amount of virus was isolated from semen collected on d 3 or 4 after treatment for two bulls but not from the other two bulls. In contrast, semen samples from all bulls were PCR positive for either or both of these 2 d. In total, from 80 semen samples, 45 were PCR positive and 26 were virus isolation positive. Thus, the PCR assay detected BHV-1 shedding in bulls earlier, more often, and for a longer duration, than did the virus isolation method.

MR of optic papilla protrusion in patients with high intracranial pressure

PURPOSE

To evaluate the signal characteristics of the optic papilla (optic nerve head) on routine cranial MR images in patients with clinical evidence of optic papilla elevation caused by high intracranial pressure, and to compare these findings with findings in healthy adult volunteers.

METHODS

We reviewed retropectively the MR imaging examinations of 15 patients who were referred with objectively decreased visual acuity and funduscopic findings of optic papilla elevation. T1-weighted and T2-weighted axial MR images were obtained by using conventional spinecho acquisitions on 1.5-T MR imagers. In addition, the MR imaging studies in 10 healthy adult volunteers without visual impairment were reviewed as controls.

RESULTS

In 10 (67%) of the 15 patients, visual elevation of the optic papilla was shown by MR imaging. In all 15 patients, the MR signal intensity of the optic papilla was hypointense relative to the vitreous of the globe on T2-weighted images. In the healthy volunteer group, the optic papillae were all similarly hypointense relative to the vitreous of the globe on T2-weighted images; however, these optic papillae were flat.

CONCLUSION

Clinical examination and MR imaging may show elevation of the optic papilla in patients with high intracranial pressure. When chronic, optic papilla elevation has been shown to correlate well with severe loss of vision. Actual edema of the optic papilla seems to play little role in the physical elevation observed clinically in the chronic stages of this pathologic process.

Arsenic-copper interaction in the kidney of the rat: influence of arsenic metabolites

The present study was an attempt to investigate whether the renal accumulation of Cu observed in the kidneys of rats and guinea-pigs exposed to arsenite (As-III) was an effect of arsenite alone or also shared by its metabolites--arsenate (As-V), dimethylarsinic acid and monomethylarsonic acid. The four arsenic compounds were administered subcutaneously and separately to rats for 12 days in increasing doses. Kidney, liver and blood were taken and analysed for As, Cu and other trace elements by atomic emission spectrometry. Results indicate that administration of As-V leads to renal Cu accumulation similar to that observed on administration of As-III and that the accumulation in both cases is dependent on the dose of arsenic, although higher doses of As-V were required to achieve renal Cu levels comparable to that of As-III. A constant molar As:Cu ratio independent of arsenic dose was obtained in the kidney. Dimethylarsinic acid did not affect renal Cu levels at all. Administration of monomethylarsonic acid led to a slight increase in renal Cu levels which did not increase further in spite of increased doses of monomethylarsonic acid. It is concluded from these studies that neither the metabolic transformation of inorganic arsenic to its methylated products nor its metabolites (dimethylarsinic acid and monomethylarsonic acid) caused the observed renal Cu accumulation, rather, the inorganic form of As, either in the trivalent or pentavalent form is responsible.

Influence of inorganic and organic arsenicals on intestinal transfer of nutrients

The effects of organic (oxophenylarsine, PhAsO 2.5-50 mumol/l) and inorganic arsenicals (As2O3 2.5-250 mumol/l; As2O5 2.5-2500 mumol/l) on intestinal transfer of water, sodium, glucose and leucine was investigated in vitro using isolated jejunal segments of male Sprague Dawley rats. All three arsenicals decreased in a dose-dependent manner the transfer of water, sodium, glucose and leucine. At the highest concentrations investigated the amount absorbed was reduced to some 10-20% of the respective control values. For both glucose and leucine the concentration ratio between absorbate and perfusate was about 3.5-4 in controls. It decreased to about 2 for leucine and to near unity for glucose. As assessed from the concentration ratio between intestinal tissue and perfusate the arsenic compounds inhibited the uptake of glucose and leucine into the tissue. There was a marked difference with respect to the potency of arsenicals, PhAsO being about 10 times more potent than As2O3 which in turn was about 5 times more potent than As2O5.

Cation-exchange liquid chromatography of choline and acetylcholine on free shielded silanols of silica-based reversed-phase stationary phases

Free anionic functions present on the surface of reversed-phase packing materials were used for the selective cation-exchange preconcentration and separation of the neurotransmitters choline and acetylcholine from a biological matrix. The cation-exchange behaviour of different reversed-phase packing materials in the neat aqueous mobile phase, the properties of an end-capped column, the dependence of capacity factors and peak shape on the concentration of counter ions, ionic strength, pH and the addition of acetonitrile and optimum conditions for enzymatic conversion of solutes to hydrogen peroxide were studied. The studied reversed-phase columns exhibit better pH stability and longer lifetimes than normal silica-based cation exchangers. Acetylcholine is an effective and sensitive test sample for the measurement of adsorption on silica support. A large sample volume was injected onto a precolumn inserted instead of an injection valve and after injection the solutes were focused and separated on an analytical column with a mobile phase containing tetramethylammonium perchlorate as the counter ion.

A modeling analysis of rest-stress and stress-rest injection sequences in performing thallium-201 myocardial perfusion scintigraphy

A new thallium-201 stress testing protocol is proposed in which rest images are obtained prior to stress images. The advantages of the new protocol are that it saves time and requires no special diet or activity restriction between imaging sets. A potential problem from reversing the standard imaging sequence is decreased sensitivity to stress perfusion defects owing to background counts from the rest image. Using a cardiac phantom, 74 sets of stress and rest images were simulated under the new protocol and the standard stress-redistribution-reinjection protocol. Seven observers were asked to classify the images as normal or abnormal and to distinguish ischemic from fixed defects. Differences in observer performances between the two protocols were compared. With the new protocol, observers had sensitivities of 75%-90% and specificities of 100% in identifying a perfusion defect on the stress study. Accuracy was improved if the image counts from the rest study contributed less than 40% of the final counts of the stress study. Detection of ischemic and fixed defects was as good as or better than with standard protocols. Based on the phantom model, rest followed immediately by stress imaging sequence is an advantageous alternative for thallium-201 stress testing. Clinical trials are necessary to further evaluate this new protocol.

The use of robots and computers in the organisation of studies on the circadian variation of beta 2-adrenoceptor sites in peripheral mononuclear leucocytes

We have developed a partially automated method for the performance of equilibrium radioligand binding studies which is applied by our group in investigations on circadian variations and stimulation studies on beta 2-adrenoceptor sites in human peripheral mononuclear leucocytes (pMNL). Using a Tecan Robotic Sample Processor, binding assays with 12 concentrations of 125iodocyanopindolol (1-150 pmol/l, total binding in triplicates, unspecific binding in the presence of 10(-5) mol/l timolol in duplicates) are prepared automatically with all titer tubes per experiment arranged in a microtiterplate-sized rack. After incubation in a waterbath for 2hr at 37 degrees C, the whole rack is centrifuged at 5000g and transferred back to the lab robot. Bound radioactivity is separated from the unbound ligand by removing the supernatant by the machine. The radioactive counts are evaluated using personal computers. The lab robot enhances reproducibility of experimental results and frees lab workers from time-consuming pipetting jobs. Radioactive exposure is minimized to the time preparing the radioligand working solution and transferring the sample tubes from the robot to the waterbath, to the centrifuge and back to the robot. The variability of our software allows easy adaptation to other binding studies with intact cells.

Inhibitors of sterol synthesis. Metabolism of 5 alpha-cholest-8(14)-en-3 beta-ol-15-one after intravenous administration to bile duct-cannulated rats

The metabolism of 5 alpha-cholest-8(14)-en-3 beta-ol-15-one has been studied after intravenous administration to bile duct-cannulated rats. Very rapid and substantial conversion of the 15-ketosterol to polar biliary metabolites was observed in both male and female rats. For example, upon intravenous injection of [4-14C]5 alpha-cholest-8(14)-en-3 beta-ol-15-one to male bile duct-cannulated rats, approximately 86% of the administered 14C was recovered in bile in the first 38 h. Of the total amount of 14C recovered in bile in 38 h, approximately 50% was excreted in bile in the first 70 min and approximately 90% was excreted within 8 h after the injection of the 15-ketosterol. A substantial fraction of the polar biliary metabolites was shown to undergo enterohepatic circulation. Of the radioactivity derived from the labeled 15-ketosterol which was not recovered in bile or other excreta at 48 h after the intravenous administration of the 15-ketosterol, most (approximately 79%) was recovered in the form of cholesterol and cholesteryl esters of blood and the various tissues. The very substantial and rapid biliary excretion of polar metabolites of the 15-ketosterol (or of cholesterol derived from the 15-ketosterol), coupled with inhibition of the intestinal absorption of cholesterol by the 15-ketosterol, may contribute to the overall hypocholesterolemic action of the 15-ketosterol which has been observed in rodents and in nonhuman primates by providing a metabolic pathway(s) wherein a substantial fraction of the absorbed 15-ketosterol is rapidly removed from the body by biliary excretion in the form of polar metabolites.

Polymorphous ventricular tachycardia: clinical characterization, therapy, and the QT interval

Forty-five consecutive patients with polymorphous ventricular tachycardia (PVT) were studied. The arrhythmia proved to be of a drug-related cause in 27 and due to an electrolyte disorder in four patients. Coexistent cardiac diseases without metabolic or drug-related abnormalities included ischemic heart disease in three, cardiomyopathy in three, and mitral valve prolapse in two. PVT was exercise-induced in four and associated with bradyarrhythmias in two. A prolonged QT or corrected QT interval was inconsistently related to the occurrence of PVT. In patients in whom PVT was induced by certain type I drugs, other type I antiarrhythmic drugs were usually either ineffective or resulted in aggravation of arrhythmia. For the group as a whole, treatment with lidocaine resulted in inconsistent beneficial effects, while cardiac pacing was almost universally effective for those with drug-induced PVT, regardless of the length of the QT interval. Long-term amiodarone therapy proved safe and effective for 12 of the 24 patients with drug-induced PVT who required long-term therapy for their original arrhythmia. We conclude that identification of PVT is the key clinical issue and that the QT interval is not necessarily the prime abnormality nor the variable to be considered in predicting success of therapy. Temporary cardiac pacing appears to be very effective in the short-term management of these patients. Use of type I antiarrhythmic agents in patients with drug-induced PVT generally resulted in aggravation of arrhythmia. In contrast, long-term amiodarone therapy for control of the original arrhythmia appears to be a promising approach for those with PVT associated with type I agents.

Mechanisms of the reductive denitration of pentachloronitrobenzene (PCNB) and the reductive dechlorination of hexachlorobenzene (HCB)

The reductive denitration of PCNB and the reductive dechlorination of HCB are complex, and begin with reaction of both fungicides with glutathione, with elimination of the nitro group and/or of chlorine, respectively. The glutathione conjugates are further metabolized by cleavage of the glycine and glutamate residues to give cysteine conjugates or N-acetylcysteine conjugates by acetylation in mammals. The cysteine derivatives are further metabolized by cleavage of the C-S bond to produce thiophenols, which after reductive desulphuration form pentachlorobenzene, or minor chlorinated benzenes, respectively.

Biotransformation of derivatives of the fungicides pentachloronitrobenzene and hexachlorobenzene in mammals

Biotransformation of N-acetyl-S-(2,3,5,6-tetrachlorophenyl)cysteine and N-acetyl-S-(pentachlorophenyl)cysteine-S-oxide, of the metabolites of both PCNB and HCB, namely N-acetyl-S-(pentachlorophenyl)cysteine, pentachlorothiophenol, pentachlorothioanisole, 4-methylthio-tetrachlorothiophenol and tetrachloro-1,4-bis(methylthio)benzene, and of the PCNB metabolites, S,S'-(tetrachloro-p-phenylene)dicysteine, and the isomeric tetrachlorothiophenols, has been studied in rabbits, rats and mice, as well as in vitro. Biotransformation products such as thiophenols, thioanisoles, chlorinated benzenes, phenols and anisoles have been identified by g.l.c.