Autonomous robotic laparoscopic surgery for intestinal anastomosis

Autonomous robotic surgery has the potential to provide efficacy, safety, and consistency independent of individual surgeon's skill and experience. Autonomous anastomosis is a challenging soft-tissue surgery task because it requires intricate imaging, tissue tracking, and surgical planning techniques, as well as a precise execution via highly adaptable control strategies often in unstructured and deformable environments. In the laparoscopic setting, such surgeries are even more challenging because of the need for high maneuverability and repeatability under motion and vision constraints. Here we describe an enhanced autonomous strategy for laparoscopic soft tissue surgery and demonstrate robotic laparoscopic small bowel anastomosis in phantom and in vivo intestinal tissues. This enhanced autonomous strategy allows the operator to select among autonomously generated surgical plans and the robot executes a wide range of tasks independently. We then use our enhanced autonomous strategy to perform in vivo autonomous robotic laparoscopic surgery for intestinal anastomosis on porcine models over a 1-week survival period. We compared the anastomosis quality criteria-including needle placement corrections, suture spacing, suture bite size, completion time, lumen patency, and leak pressure-of the developed autonomous system, manual laparoscopic surgery, and robot-assisted surgery (RAS). Data from a phantom model indicate that our system outperforms expert surgeons' manual technique and RAS technique in terms of consistency and accuracy. This was also replicated in the in vivo model. These results demonstrate that surgical robots exhibiting high levels of autonomy have the potential to improve consistency, patient outcomes, and access to a standard surgical technique.

Long-term surveillance of liver histological changes in chronic hepatitis C patients completing pegylated interferon-α plus ribavirin therapy: an observational cohort study

Background:

For chronic hepatitis C (CHC) patients completing pegylated interferon (PegIFN)-α/ribavirin therapy, long-term liver histological changes remain largely unexplored.

Methods:

This observational cohort study included 85 CHC patients completing PegIFN-α/ribavirin therapy with liver biopsies performed at baseline and the end of surveillance (EOS). Median years between paired biopsies were 6.75 (interquartile range: 5.63–7.54).

Results:

In patients with baseline METAVIR fibrosis stages (F) <4 (able to undergo fibrosis progression; n = 77), cases achieving sustained virological response (SVR) (n = 52) had a significantly lower rate of fibrosis progression than non-SVR cases (n = 25) (3.8% versus 24.0%, p = 0.012). Among the entire cohort (n = 85), the rate of activity response [METAVIR activity grades (A) decreasing or maintaining at A0] in SVR cases (n = 59) was significantly higher than that in non-SVR cases (n = 26) (94.9% versus 65.4%, p = 0.001). For SVR cases among the entire cohort, independent predictors of fibrosis clearance included baseline F <2 [odds ratio (OR) = 7.877, p = 0.042] and aspartate transaminase (AST) levels declining by >70% at EOS compared with baseline (OR = 9.013, p = 0.038). For non-SVR cases among the entire cohort, baseline AST levels >80 U/l and glucose levels ⩽ 105 mg/dl independently predicted significant fibrosis (F2/F3/F4) at EOS (OR = 12.558, p = 0.049) and activity response (OR = 17.741, p = 0.047), respectively.

Conclusions:

Among CHC patients completing PegIFN-α/ribavirin therapy, SVR lowers the risk of liver histological progression but does not guarantee fibrosis clearance. For SVR cases, those with baseline F ⩾ 2 or without significantly declined follow-up AST levels should be specifically monitored. As for non-SVR cases, those with a higher baseline AST or glucose level should preferentially receive retreatment.

Prediction of non-responsiveness to pre-dialysis care program in patients with chronic kidney disease: a retrospective cohort analysis

The responsiveness of patients with chronic kidney disease (CKD) to nephrologists’ care is unpredictable. We defined the longitudinal stages (LSs) 1–5 of estimated glomerular filtration rate (eGFR) by group-based trajectory modeling for repeated eGFR measurements of 7135 patients with CKD aged 20–90 years from a 13-year pre-end-stage renal disease (ESRD) care registry. Patients were considered nonresponsive to the pre-dialysis care if they had a more advanced eGFR LS compared with the baseline. Conversely, those with improved or stable eGFR LS were considered responsive. The proportion of patients with CKD stage progression increased with the increase in the baseline CKD stage (stages 1–2: 29.2%; stage 4: 45.8%). The adjusted times to ESRD and all-cause mortality in patients with eGFR LS-5 were 92% (95% confidence interval [CI] 86–96%) and 57% (95% CI 48–65%) shorter, respectively, than in patients with eGFR LS-3A. Among patients with baseline CKD stages 3 and 4, the adjusted times to ESRD and all-cause death in the nonresponsive patients were 39% (95% CI 33–44%) and 20% (95% CI 14–26%) shorter, respectively, than in the responsive patients. Our proposed Renal Care Responsiveness Prediction (RCRP) model performed significantly better than the conventional Kidney Failure Risk Equation in discrimination, calibration, and net benefit according to decision curve analysis. Non-responsiveness to nephrologists’ care is associated with rapid progression to ESRD and all-cause mortality. The RCRP model improves early identification of responsiveness based on variables collected during enrollment in a pre-ESRD program. Urgent attention should be given to characterize the underlying heterogeneous responsiveness to pre-dialysis care.

Prognostic roles of diabetes mellitus and hypertension in advanced hepatocellular carcinoma treated with sorafenib

BACKGROUND & AIMS

It remains limited whether diabetes mellitus (DM) and hypertension (HTN) affect the prognosis of advanced hepatocellular carcinoma (HCC) treated with sorafenib. Our study attempted to elucidate the roles of DM/HTN and the effects of diabetes medications among advanced HCC patients receiving sorafenib.

METHODS

From August 2012 to February 2018, 733 advanced HCC patients receiving sorafenib were enrolled at China Medical University, Taichung, Taiwan. According to the presence/absence of DM or HTN, they were divided into four groups: control [DM(-)/HTN(-), n = 353], DM-only [DM(+)/HTN(-), n = 91], HTN-only [DM(-)/HTN(+), n = 184] and DM+HTN groups [DM(+)/HTN(+), n = 105]. Based on the types of diabetes medications, there were three groups among DM patients (the combined cohort of DM-only and DM+HTN groups), including metformin (n = 63), non-metformin oral hypoglycemic agent (OHA) (n = 104) and regular insulin (RI)/neutral protamine hagedorn (NPH) groups (n = 29). We then assessed the survival differences between these groups.

RESULTS

DM-only and DM+HTN groups significantly presented longer overall survival (OS) than control group (control vs. DM-only, 7.70 vs. 11.83 months, p = 0.003; control vs. DM+HTN, 7.70 vs. 11.43 months, p = 0.008). However, there was no significant OS difference between control and HTN-only group (7.70 vs. 8.80 months, p = 0.111). Besides, all groups of DM patients showed significantly longer OS than control group (control vs. metformin, 7.70 vs. 12.60 months, p = 0.011; control vs. non-metformin OHA, 7.70 vs. 10.80 months, p = 0.016; control vs. RI/NPH, 7.70 vs. 15.20 months, p = 0.026).

CONCLUSIONS

Rather than HTN, DM predicts better prognosis in advanced HCC treated with sorafenib. Besides, metformin, non-metformin OHA and RI/NPH are associated with longer survival among DM-related advanced HCC patients receiving sorafenib.

Association between angiotensin receptor blockers and suicide: nationwide population-based propensity score matching study

BACKGROUND

Angiotensin receptor blockers (ARBs) have been reported to ameliorate anxiety and mood disorders in animal models. Cohort links between ARB use and suicide risk in humans require clarification.

METHODS

Data were obtained from the National Health Insurance Research Database. Patients diagnosed as having hypertension according to the criteria of the International Classification of Diseases, Ninth Revision, Clinical Modification (401-405) from January 1, 2000 to December 31, 2012 were enrolled as the target population. We defined enrollees who had received ARB prescriptions for at least 28 days as ARB users. Those who had never taken ARB prior or during the study period were defined as ARB nonusers and were propensity score-matched with ARB users. The end outcome was confirmation of a suicide attempt.

RESULTS

After propensity score matching was conducted, 40,976 ARB users and 40,976 nonusers were selected as the matched cohorts. The overall incidence rate of suicide attempt was significantly lower in ARB users than in nonusers (0.51 vs. 1.07 per 10,000 person-years; adjusted hazard ratio = 0.48, 95% confidence interval = 0.26-0.87). A Kaplan-Meier survival analysis with a log-rank test revealed a lower cumulative incidence of suicide attempt in ARB users than in nonusers (p < 0.001 for the unmatched cohort; p = 0.01 for the matched cohort).

CONCLUSIONS

ARB use was not associated with an increased risk for suicide compared with non-ARB use.

Semi-autonomous Robotic Anastomoses of Vaginal Cuffs Using Marker Enhanced 3D Imaging and Path Planning

Autonomous robotic anastomosis has the potential to improve surgical outcomes by performing more consistent suture spacing and bite size compared to manual anastomosis. However, due to soft tissue's irregular shape and unpredictable deformation, performing autonomous robotic anastomosis without continuous tissue detection and three-dimensional path planning strategies remains a challenging task. In this paper, we present a novel three-dimensional path planning algorithm for Smart Tissue Autonomous Robot (STAR) to enable semi-autonomous robotic anastomosis on deformable tissue. The algorithm incorporates (i) continuous detection of 3D near infrared (NIR) markers manually placed on deformable tissue before the procedure, (ii) generating a uniform and consistent suture placement plan using 3D path planning methods based on the locations of the NIR markers, and (iii) updating the remaining suture plan after each completed stitch using a non-rigid registration technique to account for tissue deformation during anastomosis. We evaluate the path planning algorithm for accuracy and consistency by comparing the anastomosis of synthetic vaginal cuff tissue completed by STAR and a surgeon. Our test results indicate that STAR using the proposed method achieves 2.6 times better consistency in suture spacing and 2.4 times better consistency in suture bite sizes than the manual anastomosis.

Testicular tissue cryopreservation: 8 years of experience from a coordinated network of academic centers

STUDY QUESTION

Is it feasible to disseminate testicular tissue cryopreservation with a standardized protocol through a coordinated network of centers and provide centralized processing/freezing for centers that do not have those capabilities?

SUMMARY ANSWER

Centralized processing and freezing of testicular tissue from multiple sites is feasible and accelerates recruitment, providing the statistical power to make inferences that may inform fertility preservation practice.

WHAT IS KNOWN ALREADY

Several centers in the USA and abroad are preserving testicular biopsies for patients who cannot preserve sperm in anticipation that cell- or tissue-based therapies can be used in the future to generate sperm and offspring.

STUDY DESIGN, SIZE, DURATION

Testicular tissue samples from 189 patients were cryopreserved between January 2011 and November 2018. Medical diagnosis, previous chemotherapy exposure, tissue weight, and presence of germ cells were recorded.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Human testicular tissue samples were obtained from patients undergoing treatments likely to cause infertility. Twenty five percent of the patient's tissue was donated to research and 75% was stored for patient's future use. The tissue was weighed, and research tissue was fixed for histological analysis with Periodic acid-Schiff hematoxylin staining and/or immunofluorescence staining for DEAD-box helicase 4, and/or undifferentiated embryonic cell transcription factor 1.

MAIN RESULTS AND THE ROLE OF CHANCE

The average age of fertility preservation patients was 7.9 (SD = 5) years and ranged from 5 months to 34 years. The average amount of tissue collected was 411.3 (SD = 837.3) mg and ranged from 14.4 mg-6880.2 mg. Malignancies (n = 118) were the most common indication for testicular tissue freezing, followed by blood disorders (n = 45) and other conditions (n = 26). Thirty nine percent (n = 74) of patients had initiated their chemotherapy prior to undergoing testicular biopsy. Of the 189 patients recruited to date, 137 have been analyzed for the presence of germ cells and germ cells were confirmed in 132.

LIMITATIONS, REASONS FOR CAUTION

This is a descriptive study of testicular tissues obtained from patients who were at risk of infertility. The function of spermatogonia in those biopsies could not be tested by transplantation due limited sample size.

WIDER IMPLICATIONS OF THE FINDINGS

Patients and/or guardians are willing to pursue an experimental fertility preservation procedure when no alternatives are available. Our coordinated network of centers found that many patients request fertility preservation after initiating gonadotoxic therapies. This study demonstrates that undifferentiated stem and progenitor spermatogonia may be recovered from the testicular tissues of patients who are in the early stages of their treatment and have not yet received an ablative dose of therapy. The function of those spermatogonia was not tested.

STUDY FUNDING/COMPETING INTEREST(S)

Support for the research was from the Eunice Kennedy Shriver National Institute for Child Health and Human Development grants HD061289 and HD092084, the Scaife Foundation, the Richard King Mellon Foundation, the Departments of Ob/Gyn & Reproductive Sciences and Urology of the University of Pittsburgh Medical Center, United States-Israel Binational Science Foundation (BSF), and the Kahn Foundation. The authors declare that they do not have competing financial interests.

Autonomous Laparoscopic Robotic Suturing with a Novel Actuated Suturing Tool and 3D Endoscope

Compared to open surgical techniques, laparoscopic surgical methods aim to reduce the collateral tissue damage and hence decrease the patient recovery time. However, constraints imposed by the laparoscopic surgery, i.e. the operation of surgical tools in limited spaces, turn simple surgical tasks such as suturing into time-consuming and inconsistent tasks for surgeons. In this paper, we develop an autonomous laparoscopic robotic suturing system. More specific, we expand our smart tissue anastomosis robot (STAR) by developing i) a new 3D imaging endoscope, ii) a novel actuated laparoscopic suturing tool, and iii) a suture planning strategy for the autonomous suturing. We experimentally test the accuracy and consistency of our developed system and compare it to sutures performed manually by surgeons. Our test results on suture pads indicate that STAR can reach 2.9 times better consistency in suture spacing compared to manual method and also eliminate suture repositioning and adjustments. Moreover, the consistency of suture bite sizes obtained by STAR matches with those obtained by manual suturing.

Comparative effect of antipsychotics on risk of self-harm among patients with schizophrenia

OBJECTIVE

To investigate the association of different antipsychotic treatments with hospitalization due to self-harm among patients with schizophrenia.

METHOD

This retrospective cohort study was based on Taiwan's universal health insurance database. Patients aged 15-45 years with a newly diagnosed schizophrenic disorder in 2001-2012 were included. The study outcome was the first hospitalization due to self-harm or undetermined injury after the diagnosis of schizophrenic disorders. The exposure status of antipsychotics was modeled as a time-dependent variable. The analyses were stratified by antipsychotic dosage based on defined daily dose (DDD).

RESULTS

Among 70 380 patients with a follow-up of 500 355 person-years, 2272 self-harm hospitalization episodes were identified. Compared with none or former use, current use of several second-generation antipsychotics with a dose of one DDD or above, including amisulpride, aripiprazole, clozapine, risperidone, and sulpiride, was associated with decreased risk of self-harm hospitalization, with clozapine showing the strongest effect (adjusted rate ratio = 0.26, 95% confidence interval 0.15-0.47).

CONCLUSION

The protective effect on self-harm may vary across different antipsychotics. Further studies are needed to replicate the findings.

Anesthesia for patients with tracheal bronchus

Tracheal bronchus is a congenital anatomical variant of patients with accessory bronchus in the right upper lobe deriving directly from the supracarinal trachea. Pre-operative consultation with the anesthesiologist is important for patient safety and can avoid adverse effects induced by endotracheal intubation. In this report, we described a case of tracheal bronchus in which general anesthesia was performed for video-assisted thoracoscopic surgery. We discussed some of the issues surrounding to complications in tracheal bronchus.

Polygenic risk for schizophrenia and neurocognitive performance in patients with schizophrenia

Both neurocognitive deficits and schizophrenia are highly heritable. Genetic overlap between neurocognitive deficits and schizophrenia has been observed in both the general population and in the clinical samples. This study aimed to examine if the polygenic architecture of susceptibility to schizophrenia modified neurocognitive performance in schizophrenia patients. Schizophrenia polygenic risk scores (PRSs) were first derived from the Psychiatric Genomics Consortium (PGC) on schizophrenia, and then the scores were calculated in our independent sample of 1130 schizophrenia trios, who had PsychChip data and were part of the Schizophrenia Families from Taiwan project. Pseudocontrols generated from the nontransmitted parental alleles of the parents in these trios were compared with alleles in schizophrenia patients in assessing the replicability of PGC-derived susceptibility variants. Schizophrenia PRS at the P-value threshold (PT) of 0.1 explained 0.2% in the variance of disease status in this Han-Taiwanese samples, and the score itself had a P-value 0.05 for the association test with the disorder. Each patient underwent neurocognitive evaluation on sustained attention using the continuous performance test and executive function using the Wisconsin Card Sorting Test. We applied a structural equation model to construct the neurocognitive latent variable estimated from multiple measured indices in these 2 tests, and then tested the association between the PRS and the neurocognitive latent variable. Higher schizophrenia PRS generated at the PT of 0.1 was significantly associated with poorer neurocognitive performance with explained variance 0.5%. Our findings indicated that schizophrenia susceptibility variants modify the neurocognitive performance in schizophrenia patients.

Chronic obstructive pulmonary disease and anxiety disorders: a nationwide population-based study in Taiwan

OBJECTIVE

Few studies have investigated the relationship between chronic obstructive pulmonary disease (COPD) and anxiety disorder outcomes. We sought to investigate the association in a large national sample.

METHODS

Cases were identified from Taiwan's National Health Insurance Research Database who were aged 15 years and above, with a new primary diagnosis of COPD (International Classification of Diseases, Ninth Revision codes: 491, 492, 494 and 496) between 2000 and 2007. The 29,951 cases identified were compared to 29,951 controls matched on sex, age, urban/rural residence and socioeconomic status based on insurance premium. Both groups were followed until the end of 2008 for instances of anxiety disorders. Competing risk-adjusted Cox regression analyses were applied, adjusting for matching variables, Charlson comorbidity index, hospital admission days and daily dose of prednisone.

RESULTS

Of the 59,902 subjects, 3951 were found to have anxiety disorders during a mean (SD) follow-up period of 5.5 (2.5) years. COPD, female, urban residence, lower dose of prednisone use, depressive disorders and higher outpatient visits were independent predictors of incident anxiety disorder.

CONCLUSIONS

COPD was associated with increased risk of an anxiety disorder diagnosis, independent of a number of potential confounding factors.

Risk of bipolar disorder in patients with COPD: a population-based cohort study

BAKCGROUND

Few studies have investigated the relationship between chronic obstructive pulmonary disease (COPD) and bipolar outcomes in the world. We sought to investigate the association between COPD and risk of bipolar disorder in a large national sample.

METHODS

The insured aged 15 years or more with a new primary diagnosis of COPD (ICD-9: 491, 492, 494 and 496) between 2000 and 2007 were identified from Taiwan's National Health Insurance Research Database. We included individuals with an inpatient diagnosis of COPD and/or at least 1 year of two diagnoses of COPD in outpatient services. These 35,558 cases were compared to 35,558 sex-, age-, residence- and insurance premium-matched controls. We followed both groups until the end of 2008 for incidence of bipolar disorder, defined as ICD-9 codes 296.0-296.16, 296.4-296.81 and 296.89. Competing risk-adjusted Cox regression analyses were applied with adjusting for sex, age, residence, insurance premium, prednisone use, Charlson comorbidity index, diabetes, hypertension, hyperlipidemia, cardiovascular diseases, hospital admission days, outpatients' visits and mortality.

RESULTS

Of the total 71,116 subjects, 202 were newly diagnosed with bipolar disorder during the study period. The mean follow-up time was 6.0 (SD=2.2) years. COPD, younger age, lower economic status, lower dose of prednisone use, higher hospital admission days and higher outpatient visits were independent predictors of bipolar disorder.

CONCLUSIONS

COPD was associated with increased risk of bipolar disorder independent of a number of potential confounding factors in this study.

Aberrant expression of microRNAs as biomarker for schizophrenia: from acute state to partial remission, and from peripheral blood to cortical tissue

Based on our previous finding of a seven-miRNA (hsa-miR-34a, miR-449a, miR-564, miR-432, miR-548d, miR-572 and miR-652) signature as a potential biomarker for schizophrenia, this study aimed to examine if hospitalization could affect expressions of these miRNAs. We compared their expression levels between acute state and partial remission state in people with schizophrenia (n=48) using quantitative PCR method. Further, to examine whether the blood and brain show similar expression patterns, the expressions of two miRNAs (hsa-miR-34a and hsa-miR-548d) were examined in the postmortem brain tissue of people with schizophrenia (n=25) and controls (n=27). The expression level of the seven miRNAs did not alter after ~2 months of hospitalization with significant improvement in clinical symptoms, suggesting the miRNAs could be traits rather than state-dependent markers. The aberrant expression seen in the blood of hsa-miR-34a and hsa-miR-548d were not present in the brain samples, but this does not discount the possibility that the peripheral miRNAs could be clinically useful biomarkers for schizophrenia. Unexpectedly, we found an age-dependent increase in hsa-miR-34a expressions in human cortical (Brodmann area 46 (BA46)) but not subcortical region (caudate putamen). The correlation between hsa-miR-34a expression level in BA46 and age was much stronger in the controls than in the cases, and the corresponding correlation in the blood was only seen in the cases. The association between the miRNA dysregulations, the disease predisposition and aging warrants further investigation. Taken together, this study provides further insight on the candidate peripheral miRNAs as stable biomarkers for the diagnostics of schizophrenia.

A Novel Suspended Hydrogel Membrane Platform for Cell Culture

Current cell-culture is largely performed on synthetic two-dimensional (2D) petri dishes or permeable supports such as Boyden chambers, mostly because of their ease of use and established protocols. It is generally accepted that modern cell biology research requires new physiologically relevant three-dimensional (3D) cell culture platform to mimic in vivo cell responses. To that end, we report the design and development of a suspended hydrogel membrane (ShyM) platform using gelatin methacrylate (GelMA) hydrogel. ShyM thickness (0.25–1 mm) and mechanical properties (10–70 kPa) can be varied by controlling the size of the supporting grid and concentration of GelMA prepolymer, respectively. GelMA ShyMs, with dual media exposure, were found to be compatible with both the cell-seeding and the cell-encapsulation approach as tested using murine 10T1/2 cells and demonstrated higher cellular spreading and proliferation as compared to flat GelMA unsuspended control. The utility of ShyM was also demonstrated using a case-study of invasion of cancer cells. ShyMs, similar to Boyden chambers, are compatible with standard well-plates designs and can be printed using commonly available 3D printers. In the future, ShyM can be potentially extended to variety of photosensitive hydrogels and cell types, to develop new in vitro assays to investigate complex cell–cell and cell–extracellular matrix (ECM) interactions.

Immune responses to Schistosoma haematobium infection

Urogenital schistosomiasis is one of the greatest single infectious sources of human morbidity and mortality known. Through a complex cycle of infection, migration and eventual maturation and mating, S. haematobium (the aetiological agent of urogenital schistosomiasis) deposits highly immunogenic eggs within the bladder and other pelvic organs, activating a wide range of immune programs that determine both infection outcome as well as downstream immunopathology. In this review, we discuss the experimental and observational bases for our current understanding of these immune programs, focusing specifically on how the balance of type 1 and type 2 responses governs subsequent immunopathology and clinical outcome.

Paliperidone-associated motor tics

OBJECTIVES

Paliperidone-associated motor tics.

METHOD

Case report.

RESULTS

We report a 30-year-old man with schizophrenia who developed motor tics (eye blinking) after treatment of paliperidone up to 15 mg daily.

CONCLUSION

Tic-like symptoms, from simple eye blinking to complex Tourette-like syndrome, may occur during paliperidone treatment, especially with high dose.

Synthesis and evaluation of acyl-chain- and galactose-6''-modified analogues of α-GalCer for NKT cell activation

α-GalCer is an immunostimulating glycolipid that binds to CD1d molecules and activates invariant natural killer T (iNKT) cells. Here we report a scaled-up synthesis of α-GalCer analogues with modifications in the acyl side chain and/or at the galactose 6''-position, together with their evaluation in vitro and in vivo. Analogues containing 11-phenylundecanoyl acyl side chains with aromatic substitutions (14, 16-21) and Gal-6''-phenylacetamide-substituted α-GalCer analogues bearing p-nitro- (32), p-tert-butyl (34), or o-, m-, or p-methyl groups (40-42) displayed higher IFN-γ/IL-4 secretion ratios than α-GalCer in vitro. In mice, compound 16, with an 11-(3,4-difluorophenyl)undecanoyl acyl chain, induced significant proliferation of NK and DC cells, which should be beneficial in killing tumors and priming the immune response. These new glycolipids might prove useful as adjuvants or anticancer agents.

Integrin-linked kinase is involved in TNF-alpha-induced inducible nitric-oxide synthase expression in myoblasts

Tumor necrosis factor-alpha (TNF-alpha) is a pleiotropic cytokine produced by activated macrophages. Nitric oxide (NO) is a highly reactive nitrogen radical implicated in inflammatory responses. We investigated the signaling pathway involved in inducible nitric oxide synthase (iNOS) expression and NO production stimulated by TNF-alpha in cultured myoblasts. TNF-alpha stimulation caused iNOS expression and NO production in myoblasts (G7 cells). TNF-alpha-mediated iNOS expression was attenuated by integrin-linked kinase (ILK) inhibitor (KP392) and siRNA. Pretreatment with Akt inhibitor, mammalian target of rapamycin (mTOR) inhibitor (rapamycin), NF-kappaB inhibitor (PDTC), and IkappaB protease inhibitor (TPCK) also inhibited the potentiating action of TNF-alpha. Stimulation of cells with TNF-alpha increased ILK kinase activity. TNF-alpha also increased the Akt and mTOR phosphorylation. TNF-alpha mediated an increase of NF-kappaB-specific DNA-protein complex formation, p65 translocation into nucleus, NF-kappaB-luciferase activity was inhibited by KP392, Akt inhibitor, and rapamycin. Our results suggest that TNF-alpha increased iNOS expression and NO production in myoblasts via the ILK/Akt/mTOR and NF-kappaB signaling pathway.

Genetic variants in COMT and neurocognitive impairment in families of patients with schizophrenia

This study examined the relations of genetic variants in catechol-O-methyltransferase (COMT) gene, including rs737865 in intron 1, rs4680 in exon 4 (Val158Met) and downstream rs165599, to schizophrenia and its related neurocognitive functions in families of patients with schizophrenia. Totally, 680 individuals from 166 simplex (166 affected members and 354 nonpsychotic first-degree relatives) and 46 multiplex families (85 affected members and 75 nonpsychotic first-degree relatives) were interviewed using Diagnostic Interview for Genetic Studies, administered Wisconsin Card Sorting Test (WCST) and Continuous Performance Test (CPT), and drawn for venous blood. Both categorical (dichotomizing families on affected members' neurocognitive performance) and quantitative approaches toward the WCST and CPT performance scores were employed using the family-based association test and the variance components framework, respectively. Both false discovery rate and permutations were used to adjust for multiple testing. The genotypes of rs4680 were associated with both the WCST and CPT performance scores in these families, but not with schizophrenia per se in either whole sample or subgroup analyses. Meanwhile, the other two single nucleotide polymorphisms were differentially associated with the two tasks. For WCST indexes, regardless of subgroup analyses or quantitative approach, only rs737865 exhibited moderate associations. For CPT indexes, rs737865 exhibited association for the subgroup with deficit on CPT reaction time, whereas rs165599 exhibited association for the subgroup with deficit on CPT d' as well as quantitative undegraded d'. Our results indicate that the genetic variants in COMT might be involved in modulation of neurocognitive functions and hence conferring increased risk to schizophrenia.

More evidence supports the association of PPP3CC with schizophrenia

Calcineurin is a calcium/calmodulin-dependent protein phosphatase composed of two subunits, a regulatory subunit of calcineurin B (CNB) and a catalytic subunit of calcineurin A (CNA). PPP3CC is the gamma isoform of CNA located at the chromosome 8p21.3 region. To evaluate the association between PPP3CC and schizophrenia in the Taiwanese population, 10 single nucleotide polymorphism (SNP) markers across the gene were genotyped by the method of MALDI-TOF in 218 schizophrenia families with at least two affected siblings. One SNP (rs2272080) located around the exon 1 untranslated region was nominally associated with schizophrenia (P=0.024) and significantly associated with the expression of PPP3CC in lymphoblast cell line; the TT and TG genotype had significantly higher relative expression levels than the GG genotype (P=0.0012 and 0.015, respectively). In further endophenotype stratification, the single locus of rs2272080 and the haplotypes of both two-SNP haplotype (rs7833266-rs2272080) and seven-SNP haplotype (rs2461491-rs2469758-rs2461489-rs2469770-rs2449340-rs1482337-rs2252471) showed significant associations with the subgroup of schizophrenia with deficits of the sustained attention as tested by the continuous performance test (CPT, P<0.05) and the executive functioning as tested by the Wisconsin Card Sorting Test (WCST, P<0.05). The results suggest that PPP3CC gene may be a true susceptibility gene for schizophrenia.

The effects of exercise training on walking function and perception of health status in elderly patients with peripheral arterial occlusive disease

OBJECTIVE

To determine the effects of 12-week exercise programme on ambulatory function, free-living daily physical activity and health-related quality of life in disabled older patients with intermittent claudication.

DESIGN

Prospective, randomized controlled trial.

SETTING

University Medical Center and Veterans Affairs Medical Center, Taipei, Taiwan.

SUBJECTS

Thirty-two of 64 patients with Fontaine stage II peripheral arterial occlusive disease (PAOD) were randomized to exercise training and 32 to usual care control. Five patients from the exercise group and six patients from the control group dropped out, leaving 27 and 26 patients, respectively, completing the study in each group.

INTERVENTIONS

Twelve weeks of treadmill exercise training.

MAIN OUTCOME MEASURES

Treadmill walking time to onset of claudication pain and to maximal claudication pain, 6-min walk distance, self-reported ambulatory ability and perceived health-related quality of life (QOL).

RESULTS

Compliance of exercise programme was 83% of the possible sessions. Exercise training increased treadmill walking time to onset of claudication pain by 88% (P < 0.001), time to maximal pain by 70% (P < 0.001), and 6-min walk distance by 21% (P < 0.001).

SUBJECTS

Perception of health-related QOL improved from 12% to 178% in the exercise group. These improvements were significantly better than the changes in the control group (P < 0.05).

CONCLUSIONS

Significant improvements in claudication following 12-week exercise training in elderly PAOD patients were observed. Increase in treadmill walking time to maximal claudication pain in these patients translated into the improvement of perceived physical health, which enabled the patients to become more functionally independent.

Role of right middle pulmonary vein in patients with paroxysmal atrial fibrillation

INTRODUCTION

Elimination of the ectopic foci from pulmonary veins (PVs) has proved to be a curative therapy for focal atrial fibrillation (AF). However, information about the importance of the right middle PV (RMPV) in initiation of AF and radiofrequency ablation of AF is limited.

METHOD AND RESULTS

Forty-three patients (34 men and 9 women; age 65+/-12 years) with drug-refractory paroxysmal AF underwent electrophysiologic study and catheter ablation for treatment of AF. Three-dimensional magnetic resonance angiography (MRA) of the PVs and left atrium (LA) was performed to determine the anatomic patterns of RMPV. Diameter of PV ostium was measured at the junction of the LA and each PV. MRA findings showed the following: (1) 36 (84%) of 43 patients had a discrete RMPV; (2) there are three drainage patterns of RMPV, including joining the proximal part (<1 cm from the ostium) of the right superior PV (RSPV), joining the right inferior PV (RIPV), and a separate RMPV ostium in the LA wall; and (3) the ostial diameter of RMPV was significantly smaller than RSPV and RIPV (P < 0.01). Electrophysiologic studies demonstrated that five AF foci arose from RMPV. The coupling interval between the ectopic beat of AF and sinus beat was longer in RMPV than RSPV (262+/-45 msec vs 212+/-47 msec; P = 0.043). All AFs from RMPV were ablated successfully. PV stenosis or AF recurrence from RMPV was not found during follow-up of 10+/-4 months.

CONCLUSION

RMPV was detected by MRA in >80% of paroxysmal AF patients. Ectopy from RMPV can initiate AF, and radiofrequency ablation of RMPV foci is feasible and safe.

Mechanisms of transition between double paroxysmal supraventricular tachycardias

INTRODUCTION

Coexistence of double tachycardias in one patient has been infrequently reported. Furthermore, the mechanisms of transition between double paroxysmal supraventricular tachycardias have not been well studied.

METHODS AND RESULTS

Thirty-five patients with two paroxysmal supraventricular tachycardias were studied. Group IA consisted of 3 patients with spontaneous transition between AV reciprocating tachycardia (AVRT) and AV nodal reentrant tachycardia (AVNRT). Group IB consisted of 13 patients without spontaneous transition between AVRT and AVNRT. Group IIA consisted of 5 patients with spontaneous transition between AVNRT and atrial tachycardia (AT). Group IIB consisted of 14 patients without spontaneous transition between AVNRT and AT. The absolute values of differences between the two tachycardia cycle lengths were significantly smaller in patients with than in those without transition between the two tachycardias (25+/-8 msec vs 90+/-46 msec, P < 0.05, IA vs IB; 21+/-25 msec vs 99+/-57 msec, P < 0.01, IIA vs IIB). The cutoff point of 25 msec had 80% positive predictive value for transition between the two tachycardias. Transition between two tachycardias occurred due to a spontaneous premature atrial complex (30%), conduction block at one limb of tachycardia (20%), or tachycardia-induced tachycardia (50%). Absence of transition between two tachycardias might be explained by the absence of a spontaneous premature atrial complex, longer cycle length of the first tachycardia, larger difference between two tachycardia cycle lengths, or induction of each tachycardia under different situations.

CONCLUSION

Double supraventricular tachycardias with similar tachycardia cycle lengths are vulnerable to transition between different tachycardias.

Effects of cavotricuspid isthmus ablation on atrioventricular node electrophysiology in patients with typical atrial flutter

BACKGROUND

The atrial musculature in the cavotricuspid isthmus is a part of posterior inputs to the AV node. In patients with typical atrial flutter, effects of radiofrequency ablation of this isthmus on AV node conduction are still unknown.

METHODS AND RESULTS

This study included 16 patients with clinically documented typical atrial flutter. Group 1 had 8 patients without and group 2 had 8 patients with dual AV nodal pathway physiology. Electrical pacing from the interatrial septum and low right atrium was performed to evaluate antegrade AV node function before and after ablation of the cavotricuspid isthmus. In group 1, the AV node conduction properties were similar before and after ablation. In group 2, the AV node Wenckebach cycle length and maximal AH interval during low right atrium (356+/-58 versus 399+/-49 ms, P=0.008; 303+/-57 versus 376+/-50 ms, P=0.008) and interatrial septum (365+/-62 versus 393+/-59 ms, P=0.008; 324+/-52 versus 390+/-60 ms, P=0.008) pacing were significantly longer after ablation. Elimination of the slow pathway after ablation was noted in 2 patients, including 1 with AV nodal reentrant echo beats.

CONCLUSIONS

Radiofrequency ablation of the cavotricuspid isthmus was effective in eliminating typical atrial flutter without injury of antegrade fast AV node conduction. The atrial musculature in the cavotricuspid isthmus significantly contributed to the slow AV node conduction.

Acquired pulmonary vein stenosis after radiofrequency catheter ablation of paroxysmal atrial fibrillation

INTRODUCTION

Elimination of the initiating focus within the pulmonary vein (PV) using radiofrequency (RF) catheter ablation is a new treatment modality for treatment of drug-refractory atrial fibrillation. However, information on the long-term safety of RF ablation within the PV is limited.

METHODS AND RESULTS

In 102 patients with drug-refractory atrial fibrillation and at least one initiating focus from the PV, series transesophageal echocardiography was performed to monitor the effect of RF ablation on the PV. There were 66 foci in the right upper PV and 65 foci in the left upper PV. Within 3 days of ablation, 26 of the ablated right upper PVs (39%) had increased peak Doppler flow velocity (mean 130+/-28 cm/sec, range 106 to 220), and 15 of the ablated left upper PVs (23%) had increased peak Doppler flow velocity (mean 140+/-39 cm/sec, range 105 to 219). Seven patients had increased peak Doppler flow velocity in both upper PVs. No factor (including age, sex, site of ablation, number of RF pulses, pulse duration, and temperature) could predict PV stenosis after RF ablation. Three patients with stenosis of both upper PVs experienced mild dyspnea on exertion, but only one had mild increase of pulmonary pressure. There was no significant change of peak and mean flow velocity and of PV diameter in sequential follow-up studies up to 16 (209+/-94 days) months.

CONCLUSION

Focal PV stenosis is observed frequently after RF catheter ablation applied within the vein, but usually is without clinical significance. However, ablation within multiple PVs might cause pulmonary hypertension and should be considered a limiting factor in this procedure.

The in vitro inhibitory effect of flavonoid astilbin on 3-hydroxy-3-methylglutaryl coenzyme A reductase on Vero cells

BACKGROUND

Epidemiological studies have shown that hypercholesterolemia is a major risk factor for coronary heart disease. In clinical trials of lipid lowering therapy, 3-hydroxy-3-methylglutaryl Coenzyme A (HMG-CoA) reductase inhibitor has been shown to decrease cardiac events and mortality. Flavonoids are polyphenolic natural antioxidants existing in vegetables, fruits and beverages such as tea and wine. Previous studies have shown that some antioxidants had hypocholesterolemic effect, and flavonoid intake was associated with the decrease of mortality from coronary artery disease. The aim of this study was to evaluate the inhibitory effect of flavonoids on HMG-CoA reductase.

METHODS

The methods for analysis of specific inhibitors of mevalonate biosynthesis have been well-established, using Vero cells, a cell line obtained from kidneys of African green monkeys. Flavonoids isolated from different traditional Chinese herbs were dissolved in DMSO and incubated with Vero cells with or without the addition of 1 mM mevalonate or 5 mM sodium acetate in order to observe cell growth for 24 h.

RESULTS

Concentrations of 1 mM mevalonate or 5 mM sodium acetate were added into culture medium in order to observe the effect on cell growth. Different concentrations of pravastatin to inhibit cell growth were used as a positive control. About 40 flavonoid compounds were used for study, only one compound, astilbin (belonging to the flavonol group), showed significant inhibition of Vero cell growth.

CONCLUSIONS

This study shows that one flavonoid compound, isolated from traditional medicinal herbs, may be an effective HMG-CoA reductase inhibitor which might be developed into a new hypocholesterolemic agent.

TT virus infection in screened Taiwanese blood donors

OBJECTIVE

TT virus (TTV) is a newly discovered human DNA virus of uncertain clinical significance. The aim of this study was to determine the prevalence of TTV infection among blood donors in Taiwan.

METHODS

Viral DNA was studied in 224 healthy blood donors and 118 deferred donors. DNA was extracted from plasma and amplified by seminested polymerase chain reaction with reported primer sets from a conserved region of the TTV genome.

RESULTS

The prevalence of TTV DNA in the deferred donors was 24.6%, significantly higher than in the healthy donors (11.9%). TTV was also more prevalent in those with hepatitis B surface antigen than in those without it (p = 0.002).

CONCLUSION

In comparing normal with deferred Taiwanese blood donors, hepatitis B virus infection is linked to a higher prevalence of TTV infection.

Electrophysiologic characteristics in initiation of paroxysmal atrial fibrillation from a focal area

OBJECTIVES

We investigated the electrophysiologic characteristics in the initiation of paroxysmal atrial fibrillation (PAF) from a focal area.

BACKGROUND

The electrophysiologic characteristics in the initiation of PAF are still not clear.

METHODS

The study group consisted of 77 patients (M/F = 65/12, age 66 +/- 12 years) with frequent episodes of PAF; we analyzed: 1) 15 cycle lengths of electrical activity before the onset of atrial fibrillation (AF); 2) coupling interval (CI) of the first ectopic beat just before the initiation of AF; and 3) the prematurity of an ectopic beat (prematurity index [PI] = CI/mean of preceding 15 cycle lengths).

RESULTS

A total of 111 episodes of sustained AF were identified. Two patterns of AF initiation were observed: group I (59/111, 53%) included the episodes preceded by cycle length oscillation, and group II (52/111, 47%) included the episodes initiated by a single ectopic beat with preceding cycle length relatively constant. The PI of group I episodes was significantly greater than that of group II (0.41 +/- 0.12 vs. 0.34 +/- 0.10, p < 0.01). The CI (267 +/- 54 ms vs. 217 +/- 55 ms, p < 0.05), AF1 (194 +/- 36 ms vs. 153 +/- 37 ms, p < 0.05) and PI (0.49 +/- 0.13 vs. 0.37 +/- 0.11, p < 0.01) of the AF episodes from the superior vena cava (SVC) were significantly longer and greater than those of AF episodes from pulmonary veins (PVs).

CONCLUSIONS

In patients with PAF originating from PVs or the SVC, two major initiating patterns were found. Moreover, the electrophysiologic characteristics in the initiation of AF originating from the SVC were also different from those of AF initiating from the PVs.

Metabolite and light regulation of metabolism in plants: lessons from the study of a single biochemical pathway

We are using molecular, biochemical, and genetic approaches to study the structural and regulatory genes controlling the assimilation of inorganic nitrogen into the amino acids glutamine, glutamate, aspartate and asparagine. These amino acids serve as the principal nitrogen-transport amino acids in most crop and higher plants including Arabidopsis thaliana. We have begun to investigate the regulatory mechanisms controlling nitrogen assimilation into these amino acids in plants using molecular and genetic approaches in Arabidopsis. The synthesis of the amide amino acids glutamine and asparagine is subject to tight regulation in response to environmental factors such as light and to metabolic factors such as sucrose and amino acids. For instance, light induces the expression of glutamine synthetase (GLN2) and represses expression of asparagine synthetase (ASN1) genes. This reciprocal regulation of GLN2 and ASN1 genes by light is reflected at the level of transcription and at the level of glutamine and asparagine biosynthesis. Moreover, we have shown that the regulation of these genes is also reciprocally controlled by both organic nitrogen and carbon metabolites. We have recently used a reverse genetic approach to study putative components of such metabolic sensing mechanisms in plants that may be conserved in evolution. These components include an Arabidopsis homolog for a glutamate receptor gene originally found in animal systems and a plant PII gene, which is a homolog of a component of the bacterial Ntr system. Based on our observations on the biology of both structural and regulatory genes of the nitrogen assimilatory pathway, we have developed a model for metabolic control of the genes involved in the nitrogen assimilatory pathway in plants.

Mechanism of spontaneous transition from typical atrial flutter to atrial fibrillation: role of ectopic atrial fibrillation foci

Paroxysmal AF has been known to be initiated by ectopic beats, especially in the pulmonary veins (PVs), and radiofrequency catheter ablation could cure it. We considered that the spontaneous transition from typical atrial flutter to AF also could be initiated by ectopic beats. Twenty patients (18 men, mean age 66 +/- 14 years) with episodes of spontaneous transition from typical atrial flutter to AF were included in this study. They underwent detailed mapping of both atria. All the patients had spontaneous AF initiated by ectopic beats, and all of them had typical atrial flutter and spontaneous transition from typical atrial flutter (12 patients with counterclockwise atrial flutter and 8 patients with clockwise atrial flutter) to AF. The transition was initiated by ectopic beats from the PVs (17 foci, 85%), crista terminalis (2 foci, 10%), and superior vena cava (1 focus, 5%). After successful ablation of AF foci, typical atrial flutter was induced again, but no spontaneous transition was found after at least 10 minutes of observation. We concluded that paroxysmal AF and spontaneous transition from typical atrial flutter to AF were initiated by ectopic beats, and successful catheter ablation of the ectopic foci can eliminate paroxysmal AF and spontaneous transition from typical atrial flutter to AF.

T-cell subsets mediate graft-versus-myeloid leukemia responses via different cytotoxic mechanisms

Analysis of the cytotoxic effector mechanisms by which T-cell subsets mediate graft-versus-leukemia (GVL) activity is complicated by systems that use unfractionated T cells and leukemias that express alloantigens in addition to tumor-specific antigens. In this study, we used MMB1.10, a myeloid leukemia of C57Bl/6 (B6) origin, to examine the cytolytic pathways employed by syngeneic GVL-mediating, and therefore tumor antigen-specific, T-cell subsets. Wright-Giemsa staining and flow cytometric analysis indicated that MMB1.10 cells exhibited the morphology and markers most consistent with a monocytic-myeloid origin. Although reverse transcription-polymerase chain reaction analysis revealed that MMB1.10 cells expressed tumor necrosis factor (TNF) receptor types I and H, in vitro assays suggested that these cells were resistant to TNF-alpha-mediated cytotoxicity. For study of in vivo GVL responses, mice were challenged with MMBl.10 cells, lethally irradiated, and administered anti-Thy-1-treated (T-cell-depleted) bone marrow (ATBM) either alone or in combination with T-cell subsets from MMB1.10-presensitized mice. In regard to CD4+ donor T cells, 4 x 10(6) MMB1.10-presensitized wild-type (wt) cells exhibited increased GVL responses and survival values relative to tumor-challenged recipients of ATBM only. CD4 T cells from either perforin-deficient (pfp0) or Fas ligand (FasL)-deficient (gld) mice exhibited a lower level of GVL activity but did not produce any long-term survivors. Recipients of 5 x 10(6) wt B6 CD8+ T cells had significantly improved survival relative to tumor-challenged mice that received ATBM only. The same dose of gld CD8+ T cells exhibited a reduced but significant level of GVL activity, whereas cells from mice that were perforin-deficient or cytotoxicity doubly deficient (cdd) (ie, lacking perforin and FasL) exhibited no discernable GVL activity. Doubling the gld CD8+ T-cell dose to 10(7) cells resulted in further improved survival of recipients. We conclude that GVL effects mediated by CD4+ T cells can depend on either perforin- or FasL-mediated mechanisms, whereas the CD8+ T-cell subset is heavily dependent on perforin-mediated cytotoxicity.

Differentiating the ligament of Marshall from the pulmonary vein musculature potentials in patients with paroxysmal atrial fibrillation: electrophysiological characteristics and results of radiofrequency ablation

It was reported that paroxysmal atrial fibrillation (PAF) can be initiated by ectopic atrial beats originating from the pulmonary vein (PV) or left atrial tract (LAT) within the ligament of Marshall (LOM). The aim of this study was to differentiate the LAT from the PV potentials, and to investigate the results of radiofrequency ablation guided by these potentials. Ten patients (age 60 +/- 12 years) with PAF who had a recording of double potentials (DPs) in or around the left PV were included. Group I had five patients with the second deflection of DPs (D2) due to activation of the LAT, and Group II had five patients with D2 due to activation of the PV musculature. There were no significant difference in the isoelectric interval between DPs, the activation time, and amplitude of D2 between Groups I and II. During distal coronary sinus (CS) pacing, the CS ostium (CSO) to D2 interval was shorter compared with that during sinus rhythm in Group I (39 +/- 19 vs 71 +/- 25 ms, P = 0.04), but was longer in Group II (96 +/- 16 vs 44 +/- 19 ms, P = 0.04). During ectopic activation, three patients in Group I, but no Group II patients, had transformation of recorded DPs into triple potentials. Radiofrequency ablation guided by the earliest activation of the LAT potential was performed with transient suppression of PAF, but ablation guided by the earliest activation of the PV potentials had a high success rate in eliminating PAF. In conclusion, differentiating the LAT from the PV potentials for initiation of PAF is feasible by an electrophysiological approach, and may be important for radiofrequency ablation of PAF.

A double-blind placebo-controlled study of the effectiveness and tolerability of oral stevioside in human hypertension

AIMS

Stevioside is a natural plant glycoside isolated from the plant Stevia rebaudiana which has been commercialized as a sweetener in Japan for more than 20 years. Previous animal studies have shown that stevioside has an antihypertensive effect. This study was to designed to evaluate the effect of stevioside in human hypertension.

METHODS

A multicentre, randomized, double-blind, placebo-controlled study was undertaken. This study group consisted of 106 Chinese hypertensive subjects with diastolic blood pressure between 95 and 110 mmHg and ages ranging from 28 to 75 years with 60 subjects (men 34, women 26; mean +/- s.d., 54.1+/-3.8 years) allocated to active treatment and 46 (men 19, women 27; mean +/- s.d., 53.7+/-4.1 years) to placebo treatment. Each subject was given capsules containing stevioside (250 mg) or placebo thrice daily and followed-up at monthly intervals for 1 year.

RESULTS

After 3 months, the systolic and diastolic blood pressure of the stevioside group decreased significantly (systolic: 166.0+/-9.4-152.6+/-6.8 mmHg; diastolic: 104.7 +/- 5.2-90.3+/-3.6 mmHg, P<0.05), and the effect persisted during the whole year. Blood biochemistry parameters including lipid and glucose showed no significant changes. No significant adverse effect was observed and quality of life assessment showed no deterioration.

CONCLUSIONS

This study shows that oral stevioside is a well tolerated and effective modality that may be considered as an alternative or supplementary therapy for patients with hypertension.

Effect of phenylephrine on focal atrial fibrillation originating in the pulmonary veins and superior vena cava

OBJECTIVES

This study was aimed at evaluating the effects of phenylephrine infusion on the occurrence of focal atrial fibrillation (AF).

BACKGROUND

Paroxysmal AF can be initiated by ectopic atrial beats originating in the pulmonary vein (PV) or superior vena cava (SVC). The effect of change in autonomic tone on this focal AF is unknown.

METHODS

This study included 12 patients with frequent bursts of AF documented by 24-h Holter monitoring. The number and coupling interval of spontaneous ectopic activity and bursts of AF were evaluated for 1 min before and after phenylephrine (2 to 3 microg/kg) injection.

RESULTS

After detailed mapping, four patients had a focus located in the left superior PV, six in the right superior PV and two in the SVC. In 10 patients with AF foci originating in the PVs, the frequency of ectopic activity (19.5 +/- 27.4 vs. 11.4 +/- 22.9 beats/min, p = 0.059) was reduced as well as AF bursts (14 +/- 3 vs. 1.8 +/- 2.7 bursts/min, p = 0.005) before versus after phenylephrine injection; the minimal coupling interval of ectopic activity and AF bursts became longer compared with baseline. The maximal percent increase in sinus cycle length after phenylephrine injection was significantly greater in patients with complete suppression of AF compared with those with partial suppression (43 +/- 19 vs. 14 +/- 5%, p = 0.01). However, no significant effect of phenylephrine on AF originating in the SVC was found.

CONCLUSIONS

Change in autonomic tone induced by phenylephrine injection was effective in suppressing focal AF originating in the PVs but not in the SVC.

Pulmonary vein electrogram characteristics in patients with focal sources of paroxysmal atrial fibrillation

INTRODUCTION

The major source of ectopic beats initiating paroxysmal atrial fibrillation (AF) is from pulmonary veins (PVs). However, the electrogram characteristics of PVs are not well defined.

METHODS AND RESULTS

Group I consisted of 129 patients with paroxysmal AF. Group II consisted of 10 patients with a concealed left-sided free-wall accessory pathway. All group I patients had spontaneous AF initiated by ectopic beats, including 169 ectopic foci originating from the PVs. We analyzed PV electrograms from the 169 ectopic foci during sinus beats and ectopic beats. During AF initiation, most (70%) ectopic beats showed PV spike potential followed by atrial potential; 16% of ectopic beats showed PV fragmented potential followed by atrial potential; and 14% showed fusion potentials. The coupling interval between the sinus beat and the ectopic beat was significantly shorter in the inferior PVs than in the superior PVs (171 +/- 48 msec vs 222 +/- 63 msec, P = 0.001) and was significantly shorter in the distal foci than in the ostial foci of PVs (206 +/- 52 msec vs 230 +/- 56 msec, P = 0.01). The incidence of conduction block in the PVs during AF initiation was significantly higher in the inferior PVs than in the superior PVs (12/24 vs 37/145, P = 0.03) and was significantly higher in the distal foci than in the ostial foci of PVs (43/121 vs 6/48, P = 0.04). The maximal amplitude of PV potential was significantly larger in the left PVs than in the right PVs, and the maximal duration of PV potential was significantly longer in the superior PVs than in the inferior PVs during sinus beats in both group I and II patients.

CONCLUSION

PV electrogram characteristics were different among the four PVs. Detailed mapping and careful interpretation are the most important steps in ablation of paroxysmal AF originating from PVs.

Differential use of FasL- and perforin-mediated cytolytic mechanisms by T-cell subsets involved in graft-versus-myeloid leukemia responses

In graft-versus-leukemia (GVL) responses, the cellular subsets and effector mechanisms responsible for cytotoxicity against leukemic cells in vivo remain poorly characterized. A murine model of syngeneic GVL that features CD4(+) and CD8(+) T-cell responses against the MMB3.19 myeloid leukemia cell line has been previously described. MMB3.19 expresses high levels of functional Fas and tumor necrosis factor (TNF) receptors that do not transduce proapoptotic signals. Through the use of perforin- and Fas ligand (FasL)-deficient mice, it was demonstrated that CD4(+) T cells mediate anti-MMB3.19 effects in vivo primarily through the use of FasL and secondarily through perforin mechanisms. Conversely, CD8(+) T cells induce GVL effects primarily through the use of perforin and minimally through FasL mechanisms. Although the in vivo observations of CD8(+) T cells were reflective of their in vitro cytotoxic T lymphocyte (CTL) activity, for CD4(+) T cells, in vitro responses were dominated by the perforin pathway. In addition, the diminished capacity of T cells from perforin- and FasL-deficient mice to lyse MMB3.19 target cells appeared directly related to their deficient cytotoxic functions rather than to defects in activation because these cells were fully capable of mounting proliferative responses to the tumor cells. These findings demonstrate that GVL responses of T-cell subsets can involve preferential use of different cytotoxic mechanisms. In particular, these findings identify a role for both FasL-employing CD4(+) CTLs and the more novel perforin-utilizing CD4(+) T-cell subset in responses against a myeloid leukemia.

Initiation of atrial fibrillation by ectopic beats originating from the superior vena cava: electrophysiological characteristics and results of radiofrequency ablation

BACKGROUND

The superior vena cava (SVC) has cardiac musculature extending from the right atrium. However, no previous study in humans has given details regarding the ectopic foci that initiate paroxysmal atrial fibrillation (PAF), which may originate from the SVC.

METHODS AND RESULTS

A total of 130 patients with frequent attacks of PAF initiated by ectopic beats were included. Eight patients (6%) had spontaneous AF initiated by a burst of rapid ectopic beats from the SVC (located 19+/-7 mm above the junction of the SVC and right atrium), which was confirmed by multiplane angiographic and intracardiac echocardiographic visualization and was marked by a sharp SVC potential preceding atrial activity. During initial repetitive discharges, the group with SVC ectopy had a higher incidence of intravenous conduction block than the group with pulmonary vein ectopy (75% versus 37%; P=0.03). The activation time of the earliest intracardiac ectopic activities relative to ectopic P wave onset was significantly shorter in the SVC ectopy than the pulmonary vein ectopy group (37+/-15 versus 84+/-32 ms; P<0. 001). After 5+/-3 applications of radiofrequency energy, AF was eliminated. SVC angiography after ablation revealed a local indentation of the venous wall in one patient. Two patients manifested coexisting sinus rhythm and a "focal" fibrillating activity confined inside the SVC after radiofrequency ablation. During a follow-up period of 9+/-3 months, all 8 patients were free of antiarrhythmic drugs, without tachycardia recurrence or symptoms of SVC obstruction.

CONCLUSIONS

Ectopic beats initiating PAF can originate from the SVC. A radiofrequency current delivered to eliminate these ectopies is a highly effective and safe way to prevent PAF.

Atrial tachycardias originating from the atrial septum: electrophysiologic characteristics and radiofrequency ablation

INTRODUCTION

The characteristics of atrial tachycardia (AT) have varied widely among different reports. The anatomic locations of ATs may bias the results. We propose that septal ATs and free-wall ATs have different characteristics.

METHODS AND RESULTS

One hundred forty-one patients with AT underwent electropharmacologic study, endocardial mapping, and radiofrequency ablation. Forty-nine (34.7%) patients had septal AT originating from the anteroseptal, mid-septal, and posteroseptal areas. Tachycardia cycle length was similar between septal AT and free-wall AT (367 +/- 46 msec vs 366 +/- 58 msec, P > 0.05). More patients with septal AT required isoproterenol to facilitate induction (44.9% vs 31.5%, P <.0.05). Septal AT was more sensitive to adenosine than free-wall AT (84.4% vs 67.8%, P < 0.05). Only posteroseptal AT showed a positive P wave in lead V1 and negative P wave in all the inferior leads (II, III, aVF). Radiofrequency catheter ablation had a comparable success rate for septal AT and free-wall AT (96% vs 95%) without impairment of AV conduction. During follow-up of 49 +/- 13 months (range 17 to 85), the recurrence rate was similar for septal AT and free-wall AT (3.2% vs 4.6%, P = 0.08).

CONCLUSION

Septal AT has electrophysiologic characteristics that are distinct from those of free-wall AT. Catheter ablation of the septal AT is safe and effective.

Predicting the arrhythmogenic foci of atrial fibrillation before atrial transseptal procedure: implication for catheter ablation

INTRODUCTION

Use of endocardial atrial activation sequences from recording catheters in the right atrium, His bundle, and coronary sinus to predict the location of initiating foci of atrial fibrillation (AF) before an atrial transseptal procedure has not been reported. The purpose of the present study was to develop an algorithm using endocardial atrial activation sequences to predict the location of initiating foci of AF before transseptal procedure.

METHODS AND RESULTS

Seventy-five patients (60 men and 15 women, age 68 +/- 12 years) with frequent episodes of paroxysmal AF were referred for radiofrequency ablation. By retrospective analysis, characteristics of the endocardial atrial activation sequences of right atrial, His-bundle, and coronary sinus catheters from the initial 37 patients were correlated with the location of initiating foci of AF, which were confirmed by successful ablation. The endocardial atrial activation sequences of the other 38 patients were evaluated prospectively to predict the location of initiating foci of AF before transseptal procedure using the algorithm derived from the retrospective analysis. Accuracy of the value <0 msec (obtained by subtracting the time interval between high right atrium and His-bundle atrial activation during atrial premature beats from that obtained during sinus rhythm) for discriminating the superior vena cava or upper portion of the crista terminalis from the pulmonary vein (PV) foci was 100%. When the interval between atrial activation of ostial and distal pairs of the coronary sinus catheter of the atrial premature beats was <0 msec, the accuracy for discriminating left PV foci from right PV foci was 92% in the 24 foci from the left PVs and 100% in the 19 foci from the right PVs.

CONCLUSION

Endocardial atrial activation sequences from right atrial, His-bundle, and coronary sinus catheters can accurately predict the location of initiating foci of AF before transseptal procedure. This may facilitate mapping and radiofrequency ablation of paroxysmal AF.

Radiofrequency catheter ablation of atrial fibrillation initiated by spontaneous ectopic beats

Several reports have demonstrated that most paroxysmal atrial fibrillation is initiated by ectopic beats from a focal area, and radiofrequency catheter ablation can effectively cure atrial fibrillation. Although most of the ectopic beats originate from the orifices of the pulmonary veins or from the myocardial sleeves in the pulmonary veins, ectopic beats can also originate from superior vena cava, crista terminalis, coronary sinus, ligament of Marshall, or left atrial posterior free wall. Owing to the potential risk and complexity of catheter ablation, the ideal candidates should have frequent episodes and drug refractory paroxysmal atrial fibrillation.

Dependence of electrogram duration in right posteroseptal atrium and atrium-pulmonary vein junction on pacing site: mechanism and implications regarding atrioventricular nodal reentrant tachycardia and paroxysmal atrial fibrillation

INTRODUCTION

The fractionated atrial electrogram, a signal helpful in identifying the target site for radiofrequency catheter ablation of the slow AV nodal pathway, is considered to arise from nonuniform anisotropic electrical activity. However, the effects of pacing sites and radiofrequency ablation on these electrograms are not clear. Similarly, the nature of the fractionated atrial electrogram in the atrium-pulmonary vein junction has yet to be determined.

METHODS AND RESULTS

Two experiments were performed in this study. Experiment 1 evaluated the fractionated atrial electrogram at target sites before and after slow AV nodal pathway ablation during sinus rhythm or during pacing from different sites. Group 1A consisted of 16 patients with dual AV nodal pathway physiology and AV nodal reentrant tachycardia who underwent successful ablation without residual slow AV nodal pathway. Group 1B consisted of 7 patients who underwent successful elimination of AV nodal reentry but with residual dual AV nodal pathway physiology. Group 1C consisted of 6 patients who still had AV nodal reentrant tachycardia after two applications of radiofrequency energy. In group 1D, there were 16 patients with dual AV nodal pathway physiology, but without inducible AV nodal reentrant tachycardia. In group 1E, there were 15 patients without dual AV nodal pathway physiology. Experiment 2 investigated the fractionated atrial electrogram in the ostium of the left and right superior pulmonary veins in 18 patients with paroxysmal atrial fibrillation (2A) and in 8 patients without paroxysmal atrial fibrillation (2B). Before radiofrequency ablation, electrogram duration in the right posteroseptal atrium during pacing from the middle coronary sinus or the right posterolateral atrium was shorter than that during pacing from the high right atrium (HRA) in all group 1 patients. After the successful elimination of the slow AV nodal pathway conduction in group 1A, atrial electrogram duration during HRA pacing was shorter than that before ablation. In experiment 2 patients, electrogram duration during pacing from the proximal or distal coronary sinus was shorter than that during pacing from HRA or sinus rhythm.

CONCLUSION

These findings suggest that the fractionated atrial electrograms in the right posteroseptal atrium and ostium of left or right superior pulmonary veins are potentially consistent with nonuniform anisotropic propagation. Alternations of electrogram characteristics after successful radiofrequency ablation of the slow AV nodal pathway may arise from the changes of nonuniform anisotropic activity in the right posteroseptal atrium.

Ventricular tachycardia in a patient with primary hyperparathyroidism

We present a case of primary hyperparathyroidism with hypercalcemia in a patient who had spontaneous attacks of ventricular tachycardia. Right ventricular burst pacing reproducibly induced ventricular tachycardia in the electrophysiological laboratory after intravenous administration of calcium-gluconate, and verapamil could terminate the tachycardia. After resection of the parathyroid adenoma, the calcium level was restored to normal, and ventricular tachycardia did not occur again during the follow-up period.