[Efficacy and safety of low-dose rasburicase for refractory chronic gouty arthritis]

Objective: To explore the efficacy and safety of low-dose rasburicase for refractory chronic gouty arthritis. Methods: A cohort study. The clinical data of patients with refractory chronic gouty arthritis who were treated with rasburicase at Sun Yat-sen Memorial Hospital, Sun Yat-sen University between January 2021 and July 2022 were retrospectively analyzed. Refractory chronic gouty arthritis was defined as serum uric acid (sUA)>360 μmol/L and urate volume>10 cm³ under dual-energy computed tomography after tolerable maximal oral urate-lowering therapy for at least 3 months. The administration of low-dose rasburicase was applied intravenously with total dosage ranging from 4.5 to 7.5 mg each dose, at 4-week intervals for a maximum of three doses. Efficacy was evaluated by the changes of sUA level, tophus and urate volume. Results: A total of 22 patients were included for analysis, with 95.4% (21/22) male, the mean age was (44±15) years, and the median duration of gout was 11 (6-15) years. The mean sUA at baseline was (667±112) μmol/L. The levels of sUA significantly decreased after each dose of rasburicase (P<0.001), and the median reduction of sUA after each dose of rasburicase was 568 (471-635), 187 (66-335) and 123 (49-207) μmol/L, respectively. At week 12, nine patients (40.9%) exhibited sUA<360 μmol/L and tophus disappeared in one patient. The urate volume significantly decreased at week 12 when compared with that before the first dose of rasburicase in all the patients [40 (16-172) cm³ vs 17 (7-134) cm³, P<0.001], with a median reduction rate of 41.6% (22.9%-58.5%). The everall safety of rasburicase was good, and no serious adverse reactions occurred. Conclusions: Low-dose rasburicase is well-tolerated and effective for decreasing the urate burden in patients with refractory chronic gouty arthritis. Further prospective randomized controlled trials are needed to validate these findings.

[The mechanism of circ_0023990/miR-873-5p/ANXA2 axis regulating radiosensitivity and development of thyroid carcinoma]

Objective: To explore the effect and possible mechanism of circ_0023990 on the radiosensitivity of thyroid cancer cells. Methods: qRT-PCR was used to detect the expression of circ_0023990 in the cancer tissues of 55 patients with thyroid cancer and thyroid cancer cell lines (TPC-1, KTC-1, FTC-133 and CAL-62), and the relationship between the expression of circ_0023990 in cancer tissues and the clinical characteristics of the patients were analyzed. Thyroid cancer cells TPC-1 and KTC-1 were divided into sh-circ_0023990 group, sh-NC group, sh-circ_0023990+anti-miR-873-5p group, sh-circ_0023990+anti-miR-NC group, miR-873-5p group, miR-NC group, miR-873-5p+pcDNA-ANXA2 group and miR-873-5p+pcDNA group, and then clone formation experiment was used to detect cell radiosensitivity. After each group of cells was irradiated with 4Gy radiation, the expression of γH2AX protein in the cells was detected by Western Blot. The dual luciferase reporter gene experiment verified the targeting relationship between circ_0023990 and miR-873-5p or miR-873-5p and ANXA2. Results: The expression of circ_0023990 in thyroid cancer tissues was higher than that in normal tissues (2.15±0.09 vs. 0.97±0.05, P<0.05), and its expression was closely related to tumor size, lymph node metastasis and TNM staging of patients with thyroid cancer (P<0.05). The expression of circ_0023990 in thyroid cancer cell lines (TPC-1, KTC-1, FTC-133 and CAL-62) were higher than that of normal thyroid cells HTori-3 (3.16±0.38, 2.63±0.28, 1.82±0.24, 1.71±0.22 vs. 1.00±0.10, all P<0.05). The survival scores of TPC-1 and KTC-1 cells in the sh-circ_0023990 group were significantly lower than those in the sh-NC group (P<0.05), and the sensitization ratios were 2.482, 1.643; The survival scores of TPC-1 and KTC-1 cells in the sh-circ_0023990+anti-miR-873-5p group were higher than those in the sh-circ_0023990+anti-miR-NC group (P<0.05), and the sensitization ratios were 0.305, 0.441, respectively. The survival scores of TPC-1 and KTC-1 cells in the miR-873-5p group were lower than those in the miR-NC group (P<0.05), and the sensitization ratios were 2.044, 1.653 respectively. The survival scores of TPC-1 and KTC-1 cells in the miR-873-5p+pcDNA-ANXA2 group was higher than that in the miR-873-5p+pcDNA group (P<0.05), and the sensitization ratios were 0.496, 0.686, respectively. The expression of γH2AX protein in TPC-1 and KTC-1 cells of the 4 Gy+sh-circ_0023990 group were higher than that in the 4 Gy+sh-NC group (2.68±0.27 vs. 1.87±0.25, 2.46±0.19 vs. 1.77±0.14; all P<0.05), but the expression of γH2AX protein in TPC-1 and KTC-1 cells of the 4 Gy+sh-circ_0023990+anti-miR-873-5p group were lower than that in the 4 Gy+sh-circ_0023990+anti-miR-NC group (1.13±0.09 vs. 1.69±0.09, 1.11±0.08 vs. 1.60±0.08; both P<0.05). The expression of γH2AX protein in TPC-1 and KTC-1 cells in the 4 Gy+miR-873-5p group were higher than that in the 4 Gy+miR-NC group (2.35±0.16 vs. 1.84±0.14, 2.26±0.12 vs. 1.77±0.13; both P<0.05), but the expression of γH2AX protein in TPC-1 and KTC-1 cells of the 4 Gy+miR-873-5p+pcDNA-ANXA2 group were lower than that in the 4 Gy+miR-873-5p+pcDNA group (1.96±0.12 vs. 2.41±0.12, 1.92±0.07 vs. 2.28±0.12; both P<0.05). circ_0023990 targeted the negative regulation of miR-873-5p, and ANXA2 was the target gene of miR-873-5p. Conclusion: circ_0023990 was highly expressed in thyroid cancer tissues and cell lines, and it may promote the radiotherapy resistance of thyroid cancer cells in vivo through regulating miR-873-5p/ANXA2 axis.

[Predictive value of anti-mutated citrullinated vimentin antibody on one-year radiographic progression in patients with rheumatoid arthritis]

Objective: To investigate the value of baseline anti-mutated citrullinated vimentin (MCV) antibody for predicting one-year radiographic progression in patients with rheumatoid arthritis (RA). Methods: Consecutive RA patients were recruited from November 2014 to July 2018 at Department of Rheumatology, Sun Yat-sen Memorial Hospital, Clinical data were collected including disease activity score in 28 joints with four variables including C-reactive protein (CRP).Serum anti-MCV antibody at baseline was detected by enzyme-linked immunosorbent assay. X ray assessment of both hands/wrists was performed and assessed according to the Sharp/van der Heijde modified score (mTSS) at baseline and the 12th month. Univariate and multivariate logistic regression analyses were used to identify the risk factors for one-year radiographic progression. Results: Among 220 RA patients recruited, the positive rate of anti-MCV antibody at baseline was 77.7%. Compared with those with negative anti-MCV antibody, RA patients with positive anti-MCV antibody had higher disease activity score in 28 joints with four variables induding CRP [3.8 (2.4, 5.0) vs. 3.1 (2.1, 4.0), P=0.007], more physical dysfunction (21.6% vs. 8.2%, P=0.033) and higher radiographic indicators including mTSS [11 (2, 27) vs. 4 (1, 10), P=0.003], joint space narrowing [JSN, 4 (0, 14) vs. 2 (0, 6), P=0.024] and joint erosion[JE, 5 (1, 18)vs. 3 (0, 5), P=0.003]. After one-year follow-up, sixty-six RA patients (30.0%) developed radiographic progression, the percentage of whom was significantly higher in positive anti-MCV group than that in negative anti-MCV group (33.9% vs.16.3%, P=0.018). Multivariate logistic regression analysis suggested that positive anti-MCV antibody at baseline was an independent risk factor for one-year radiographic progression (OR=2.341, 95%CI 1.002-5.469). Conclusion: Positive anti-MCV antibody at baseline predicts one-year radiographic progression in RA patients. In the future, anti-MCV antibody can be used not only as a supplementary laboratory marker, but also in disease activity assessment and prognosis prediction for RA.

[Targeted therapy of pyogenic sterile arthritis, pyoderma gangrenosum, and acne syndrome (PAPA): a case report and literature review]

Objective: To analyze the clinical course and targeted therapy of pyogenic sterile arthritis, pyoderma gangrenosum, and acne (PAPA) syndrome. Methods: The clinical history of a 6-year-old boy with PAPA syndrome, who was admitted to Hong Kong University Shenzhen Hospital in September 2017, was reviewed. His genetic diagnosis was confirmed by whole exome sequencing. The response to targeted therapy was evaluated by comparing the inflammatory markers (erythrocyte sedimentation rate (ESR) and C reactive protein (CRP) and serum cytokines (interleukin (IL)-1, IL-6 and tumor necrosis factor-α (TNF-α)) before and after biological agents treatment. For literature review, "PAPA syndrome" and"PSTPIP1 gene"were used as keywords to retrieve papers published from January 1997 to December 2019 from Pubmed, Wanfang and CNKI database. Results: The patient was a 6-year-old boy, admitted to the hospital due to recurrent joint swelling and pain for more than 4 years. Before treatment, the CRP (256 mg/L), ESR (105 mm/1 h) and cytokines including serum TNF-α (7.43 ng/L), IL-1 (<5 ng/L), IL-6 (301 ng/L) were significantly elevated. Culture of the joint effusion was negative, but the IL-6 level was above 1 000 ng/L. MRI showed osteomyelitis at the lower end of the right femur. Gene detection found a heterozygous variation of PSTPIP1 gene (c.748G>A, p.E250K). Arthralgia once alleviated after the initiation of tocilizumab and infliximab, but recurred after 1 year of treatment. Thereafter, the anti-IL-1 receptor antagonist (Anakinra) was commenced, followed by a significant improvement of the arthralgia, and a complete remission during the follow-up. Besides, the level of CRP, ESR, serum TNF-α, IL-1 and IL-6 were all decreased to normal on the last followed up in December 2019. Literature review found 29 articles and 87 patients in total. The initial symptoms included those of arthritis (n=58), pyoderma gangrenosum (n=33), and acne (n=24). Among all the cases, 13 genotypes were confirmed, and 47 variations involved amino acid p.E250. Steroid and/or biological agents were used in most patients. Conclusions: PAPA syndrome should be suspected in children with recurrent pyogenic sterile arthritis, and an early diagnosis could be achieved by genetic test. Targeted treatment with biological agent may control the symptoms effectively. Biological agents can control symptoms of this disorder effectively.

Antimicrobial resistance and virulence genes of Streptococcus isolated from dairy cows with mastitis in China

Streptococcus is a major mastitis-causing pathogen in dairy cows. To investigate the prevalence, antimicrobial resistance and virulence gene of Streptococcus in mastitic milk, a total of 735 mastitic raw milk samples from dairy cows in 11 provinces of China were collected and tested. Antimicrobial resistance of Streptococcus isolates was determined by disc diffusion against 8 classes 29 antimicrobial agents, and Streptococcus resistant genes and virulence genes were determined by PCR and agarose gel electrophoresis. A total of 64 (8.71%) isolates of Streptococcus were isolated and identified using biochemical profiling, including 22 isolates of Streptococcus agalactiae, 13 isolates of Streptococcus dysgalactiae, and 29 isolates of Streptococcus uberis. Out of 64 resistant Streptococcus isolates, all isolates (100%) were resistant to 3 or more antimicrobials. The most frequency (n = 18, 28.12%) of the isolates were multi-resistant to 5-7 antimicrobials and the highest multi-resistant number was 29 (n = 1, 1.56%). Streptococcus isolates had the highest resistance rate to tetracycline (98.44%) and oxacillin (98.44%), followed by penicillin G (96.88%) and doxycycline (96.88%), and the lowest resistance was observed with respect to ciprofloxacin (1.56%). A total of 16 antimicrobials resistance genes with 25 combination patterns were detected in the isolates. The gene combination of Sul1/Sul2/Sul3 + gyrA/parC + cat1/cat2 was the most common pattern (12.5%). The correlation between resistant phenotypes and resistance genes in Streptococcs was 35.87%. A total of 7 virulence genes were detected and 59 (92.19%) isolates harbored at least one gene. Twenty-four classes of gene patterns were found in the isolates and the patterns of bca (9.38%) and cfb (9.38%) were the most prevalent form. In conclusion, the issue of drug resistance of Streptococcus is still a great concern in cattle health in China.

[Influence of high-fat diet in paternal C57BL/6 mice on liver fat deposition in offspring]

Objective: To investigate the influence of high-fat diet (HFD) in paternal C57BL/6 mice on HFD-induced liver fat deposition in male offspring, as well as transgenerational inheritance caused by paternal HFD and related mechanisms. Methods: A total of 20 male C57BL/6 mice aged 3 weeks (F0) were randomly divided into normal control group (C, 10 mice) and HFD group (HF, 10 mice). After 12 weeks of HFD intervention, the male mice in the HFD group mated with female ones treated with normal diet and pups were obtained. Male pups (F1) were selected as study subjects. According to the intervention for F0 mice, male F1 mice were divided into control male offspring group (CM, 8 mice) and HFD male offspring group (HFM, 9 mice). All these mice were given normal diet after weaning until 4 weeks old, followed by HFD for 4 weeks. The body length and body weight were measured and recorded every week. Oil red O staining was used to observe fat deposition in the liver. Western blot and real-time PCR were used to measure the expression of related proteins and genes involved in the de novo synthesis and aerobic oxidation of fatty acid, mitochondriogenesis, and autophagy. Results: After 4 weeks of HFD intervention, the HFM group had a significantly higher body weight than the CM group (P < 0.05); the oil red O staining showed that compared with the CM group, the HFM had a significant increase in liver fat deposition and a significantly higher integral absorbance value in the oil red O staining-positive area (384 360±57 600 vs 236 754±12 607, P < 0.01). For related factors involved in the de novo synthesis of fatty acid in the liver, compared with the CM group, the HFM group had significant increases in the expression of sterol regulatory element-binding protein-1 and fatty acid synthase (P < 0.05); for related factors involved in the mitochondrial biosynthesis in the liver, the HFM group had significant reductions in the relative expression of peroxisome proliferator-activated receptor-γ coactivator-1α, nuclear respiratory factor 1, and mitochondrial transcription factor A compared with the CM group (P < 0.05). For autophagy-related factors in the liver in the F1 mice, compared with the CM group, the HFM group had a significant reduction in microtubule-associated protein I light chain 3 (LC3-II/I) (P < 0.05) and a significant increase in P62 (P < 0.05), suggesting a reduced autophagy function in the liver. Conclusion: HFD intervention for paternal C57BL/6 mice can increase HFD-induced liver fat deposition in male offspring, which may be related to the increased de novo synthesis of fatty acid and reduced mitochondriogenesis and autophagy function in the liver.

Historical records of trace metals in core sediments from the Lianyungang coastal sea, Jiangsu, China

We analyzed element concentrations in cores from the Lianyungang coastal sea to determine depositional trends and geochemical sources of metals. Enrichment factors (EFs) and pollution load index (PLI) were used to assess the enrichment and pollution of metals. Profiles of vertical distributions of the elements reflected different depositional environments in 3 cores. Cores A and C deposited sediments with rich terrestrial elements by rivers, corresponding to mixed-up patterns in the sediment. Meanwhile, core B was mainly deposited in a less undisturbed depositional environment. Correlations and principal component analysis indicated that sediments were influenced by natural and anthropogenic impacts. According to the EFs, most metals showed no significant enrichment and pollution in the core sediments. Lastly, PLI values (<1) of sediments indicated that the Lianyungang coastal sea was a lowly polluted area despite PLI value of metals in average sediment was lower than that in surface sediment.

Pollution in the urban soils of Lianyungang, China, evaluated using a pollution index, mobility of heavy metals, and enzymatic activities

Soil samples from 16 urban sites in Lianyungang, China were collected and analyzed. A pollution index was used to assess the potential ecological risk of heavy metals and a sequential extraction procedure was used to evaluate the relative distribution of Cu, Zn, Pb, Cd, Cr, and As in exchangeable, carbonate, Fe/Mn oxide, organic/sulfide, and residual fractions. The mobility of heavy metals and urease (URE) activity, alkaline phosphatase (ALP) activity, and invertase (INV) activity of soils was determined. The results showed that the average concentrations of Cu, Zn, Pb, Cd, Cr, and As in Lianyungang soils were much higher than those in the coastal city soil background values of Jiangsu and China. Among the five studied regions (utilities, commercial, industrial, tourism, and roadside), the industrial region had the highest metal concentrations demonstrating that land use had a significant impact on the accumulation of heavy metals in Lianyungang soils. Compared to the other metals, Cd showed the highest ecological risk. According to chemical partitioning, Cu was associated with the organic/sulfides and Pb and Zn were mainly in the carbonate and the Fe/Mn oxide phase. The greatest amounts of Cd were found in exchangeable and carbonate fractions, while Cr and As were mainly in the residual fraction. Cd had the highest mobility of all metals, and the order of mobility (highest to lowest) of heavy metals in Lianyungang soils was Cd > Zn > Pb > Cu > As > Cr. Soil urease activity, alkaline phosphatase activity, and invertase activity varied considerably in different pollution degree sites. Soil enzyme activities had the lowest levels in roadside and industrial regions. Across all the soil data in the five regions, the total Cu, Zn, Pb, Cd, Cr, and As level was negatively correlated with urease activity, alkaline phosphatase activity, and invertase activity, but the relationship was not significant. In the industrial region, alkaline phosphatase activity had significant negative correlations with total Cu, Pb, Cr, Zn, Cd, and heavy metal fractions. This showed that alkaline phosphatase activity was sensitive to heavy metals in heavily contaminated regions, whereas urease and invertase were less affected. The combination of the various methods may offer a powerful analytical technique in the study of heavy metal pollution in street soil.

Relative contributions of testosterone deficiency and metabolism syndrome at the risk of reduced quality of life: A cross-sectional study among Chinese mid-aged and elderly men

Testosterone deficiency and metabolism syndrome (MetS) are universal among ageing males, and they have been suggested responsible for poorer quality of life (QoL). We aimed to evaluate the relative contributions of reproductive hormones and components of MetS at the risk of reduced QoL among Chinese mid-aged and elderly men. A cross-sectional study recruited 2,364 males aged 40-79 years, and 2,165 was included for analysis eventually. The Chinese version of ageing male symptoms scale, 36-item Short Form and Beck Depression Inventory were applied to assess QoL. Bivariate correlation analysis and multiple linear regression analysis were used to assess the relative contributions of reproductive hormones and components of MetS at the risk of reduced QoL. Testosterone deficiency and MetS contributed to poorer QoL, of which higher fasting blood glucose made the primary contribution, lower total testosterone mainly contributed to poorer physical functioning.

Potential confounding factors in measurement of specific cell-free seminal mRNAs and microRNAs derived from human reproductive organs

Cell-free seminal RNA (cfs-RNA) is mixed transcripts derived from male reproductive organs, and is potential biomarker for the research and diagnosis of male reproductive-related diseases. However, some clinical factors, including age, asymptomatic Ureaplasma urealyticum (UU) infection, scrotal heat stress, abstinence period, and the storage condition of semen samples, may interfere with sperm parameters and the measurement of seminal biomarkers. Accordingly, this study was designed to evaluate the effect of above clinical factors on the measurement of cfs-RNA, aiming to lay a foundation for its research use and potential clinical application. Semen samples were collected according to the selected clinical factors. Cell-free seminal plasma was obtained by centrifugation and total RNA was extracted with TRIzol LS. Selective male reproductive organ-specific cfs-mRNAs and cfs-miRNAs were quantified by quantitative real-time PCR. The concentration and total amount of cfs-mRNAs and cfs-miRNAs in one ejaculate were calculated and compared. ACTB, DDX4 (testis-specific), WFDC9 (epididymis-specific), and miR-514a-3p (testis-specific) significantly increased after scrotal heat stress. SEMG1 (seminal vesicle-specific) showed declining tendency with the prolonged abstinence period. Age, asymptomatic UU infection, and the storage condition showed no significant impact on the measurement of cfs-RNA. These results indicate that scrotal heat stress significantly interfere with the selected cfs-RNA derived from the testis and epididymis, and abstinence period may affect the yield of cfs-mRNA from seminal vesicle, while other clinical factors has no significant impact on the measurement. Thus, heat exposure and abstinence period should be considered for the cfs-RNA measurement in its research or clinical application.

Importance of CD44 on umbilical cord mesenchymal stem cells for expansion of hematopoietic cells

Human umbilical cord mesenchymal stem cells (hUCMSCs) have important functions on the expansion of hematopoietic stem cells (HSCs) through providing the essential microenvironment for hematopoiesis. In order to test whether CD44 on hUCMSCs could have a key function for the ability of hUCMSCs to expand human HSCs, the soluble anti&mdash;CD44 antibody was added to the co&mdash;cultures of hUCMSCs and cord blood (CB) CD34+ cells, which blocked the ability of hUCMSCs to expand CB CD34+ cells significantly. Long&mdash;term culture initiating cell (LTC&mdash;IC) assay revealed that the ability of multipotent differentiation of CB CD34+ cells co&mdash;cultured with CD44 knockdown hUCMSCs could only retain lasting at most for 5 weeks in vitro. In vivo assay, based on non&mdash;obese diabetic/severe combined immunodeficient disease (NOD/SCID) mice, revealed that the hematopoietic reconstitution potential of CB CD34+ cells co&mdash;cultured with CD44 knockdown hUCMSCs is significantly reduced. The hematopoietic supporting ability of hUCMSCs in vivo and in vitro is reduced upon the knockdown of CD44. CD44 has important functions on the ability of hUCMSCs to expand human HSCs in the cell&mdash; extrinsic control.

IL-8 -251T/A polymorphism is associated with susceptibility to acute pancreatitis

We conducted a case-control study to clarify the asso-ciations between inflammatory cytokine, including interleukin (IL)-1b, IL-6, IL-8, and IL-10, polymorphisms and risk of acute pancreatitis. Genotyping analyses of IL-1β+3954 C/T (rs1143634), IL-1β-511 C/T (rs16944), IL-6 -174 G/C (rs1800795), IL-6 -634 C/G (rs1800796), IL-8 -251T/A (rs4073), IL-10 -1082A/G (rs1800896), and IL-10 -819C/T (rs1800871) were conducted using polymerase chain reaction-restriction fragment length of polymorphism. Unconditional logistic regression analysis was utilized to assess the potential association be-tween genotype frequencies and risk of acute pancreatitis. Multivari-ate regression analyses showed that subjects carrying the IL-8 -251 AA genotype had a significantly increased risk of acute pancreatitis, with an adjusted odds ratio (95% confidence interval) of 1.55 (1.02-2.36). However, we found no significant association between IL-1β +3954 C/T, IL-1β -511 C/T, IL-6 -174 G/C, IL-6 -174 G/C, IL-6 -634 C/G, IL-10 -1082A/G, or IL-10 -819C/T polymorphisms and risk of acute pancreatitis. We found that the IL-8 -251T/A polymorphism was associated with a higher susceptibility to acute pancreatitis in a Chinese population.

Effects of heat stress on survival of Frankliniella occidentalis (Thysanoptera: Thripidae) and Thrips tabaci (Thysanoptera: Thripidae)

Temperature is known to play a crucial role in the population dynamics of insects. Insects have evolved different mechanisms to resist unfavorable extreme temperatures. In recent years, western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), and onion thrips, Thrips tabaci (Lindeman) (Thysanoptera: Thripidae), have caused significant damage to vegetable crops. Because of global warming and expanding areas of vegetable cultivation, a study of the effects of heat stress on these thrips species is warranted. We exposed the various developmental stages of western flower thrips and onion thrips to temperatures of 41, 43, or 45 degrees C for 2, 6, 12, 24, or 36 h to determine the effects of heat stress on survival. Our results showed that the heat resistance of nonadult western flower thrips was greater than that of the nonadult onion thrips, and that the natural heat resistant ability was the primary factor in heat resistance in western flower thrips. In contrast, the heat resistance of adult onion thrips was greater than that of the adult western flower thrips, which was primarily the result of the ability of searching suitable microenvironment that enabled the onion thrips to mitigate the effects of high temperatures more efficiently than the western flower thrips. Our analysis of the differences in heat resistance between western flower thrips and onion thrips provides important information for the development of thermal treatments for controlling western flower thrips and onion thrips.

Development and characterization of SSR markers from Pinus massoniana and their transferability to P. elliottii, P. caribaea and P. yunnanensis

Pinus massoniana (Masson's pine) is a widespread tree species in central and southern China and northern Vietnam; it is valued for rosin and paper production. Despite the significant economic value of Masson's pine, little work has been done on its molecular genetics. We developed 318 SSR primers from genome sequences of P. massoniana, and we identified 10 polymorphic markers. The number of alleles in the population of P. massoniana that we examined ranged from two to four, and the Shannon diversity index ranged from 0.150 to 1.133. Cross-species transferability of the 318 SSRs was also analyzed in the slash pine (Pinus elliottii), the Caribbean pine (Pinus caribaea) and the Yunnan pine (Pinus yunnanensis); 15, 10, and 10 primer pairs generated polymorphic amplification, respectively. These sets of polymorphic SSR markers will be useful for population genetics studies of P. massoniana, for genetic identification of interspecific hybridization, and for phylogeographic studies of Pinus spp.

Hypoxia-inducible factor 1α cDNA cloning and its mRNA and protein tissue specific expression in domestic yak (Bos grunniens) from Qinghai-Tibetan plateau

Adaptation to hypoxia is regulated by hypoxia-inducible factor 1 (HIF-1), a heterodimeric transcription factor consisting of an oxygen-regulated alpha-subunit and a constitutively expressed beta-subunit. How animals living on Qinghai-Tibetan plateau adapt to the extreme hypoxia environment is known indistinctly. In this study, the Qinghai yak, which has been living at 3000-5000 m altitude for at least two millions of years, was selected as the model of high hypoxia-tolerant adaptation species. The HIF-1alpha ORFs (open reading frames) encoding for two isoforms of HIF-1alpha have been cloned from the brain of the domestic yak. Its expression of HIF-1alpha was analyzed at both mRNA and protein levels in various tissues. Both its HIF-1alpha mRNA and protein are tissue specific expression. Its HIF-1alpha protein's high expression in the brain, lung, and kidney showed us that HIF-1alpha protein may play an important role in the adaptation to hypoxia environment.

Leptin cDNA cloning and its mRNA expression in plateau pikas (Ochotona curzoniae) from different altitudes on Qinghai-Tibet Plateau

Leptin, an adipocyte-derived hormone, plays an important role in body energy homeostasis. Plateau pika (Ochotona curzoniae), an endemic and keystone species living only at 3000-5000 m above sea level on Qinghai-Tibet Plateau, is a typically high hypoxia and low temperature tolerant mammal with high resting metabolic rate (RMR), non-shivering thermogenesis (NST), and high ratio of oxygen utilization to cope with harsh plateau environment. To explore the molecular mechanism of ecological acclimation in plateau pika, we first cloned pika leptin cDNA and compared its mRNA expression in different altitudes (3200 and 3900 m) using real-time RT-PCR (Taqman probe) technology. The full-length pika leptin cDNA was 3015 with 504 bp open-reading frame encoding the precursor peptide of 167 amino acids including 21 residues of signal peptide. Pika leptin was 70-72% homologous to that of other species and was of similarly structural characteristics with other species. The pika-specific genetic diversity in leptin sequence occurred at twenty sites. With the increase in altitude, there were larger fat store and high level of ob gene expression in plateau pika. Our results indicated that leptin is sensitive to cold and hypoxia plateau environment and may play one of important roles in pika's ecological adaptation to harsh plateau environment.

Spontaneous, electrically, and cesium chloride induced arrhythmia and afterdepolarizations in the rapidly paced dog heart

Despite frequent arrhythmia and sudden death in heart failure, attempts to study arrhythmia mechanisms in patients are difficult. The dog heart, paced for several weeks at a fast rate to induce heart failure is prone to arrhythmia. The aim of this study was to determine the activation patterns of spontaneous and electrically induced arrhythmia and the susceptibility of the failing dog heart to arrhythmia and early afterdepolarization (EAD) induced triggered activity elicited by exogenous administration of cesium chloride (CsCl). The hearts of 56 mongrel dogs were paced at 240 beats/min for 3-5 weeks (heart failure group). Twenty-one similarly operated, but not paced dogs served as the control group. At baseline, all dogs were healthy as assessed electrophysiologically and hemodynamically. Spontaneous (bradycardia, tachycardia, and arrhythmic deaths) and electrically induced arrhythmia was frequent in dogs with heart failure. Also, the minimal dose of CsCl that produced ventricular tachycardia was significantly lower in the heart failure than the control dogs (1.02 +/- 0.02 vs 1.21 +/- 0.07 mMol/kg, P < 0.05). Epicardial mapping during spontaneous and electrically induced arrhythmia in the heart failure dogs showed initiation patterns with focal origin, often from multiple sites. This pattern was consistent with the patterns observed with CsCl induced ventricular tachycardia. In in vitro microelectrode studies, CsCl superfusion (2.5-5 mMol/L) induced triggered activity due to EADs within 30 minutes, in seven of the eight Purkinje fibers from four heart failure dogs. EADs were also found in ventricular myocytes of papillary muscle from two heart failure dogs. In contrast, 5 mMol/L CsCl induced EADs in only one of eight Purkinje fibers from the hearts of four control dogs and no papillary myocytes even with continuous superfusion for up to 60 minutes (P < 0.01). These results demonstrate that pacing induced heart failure in the dog has an increased tendency to develop ventricular tachycardia and triggered activity unmasked by CsCl.

Nucleophilic substitution at the imidoyl carbon atom: intermediate mechanistic and reactivity behavior between carbonyl and vinyl carbon substitution

Gas-phase nucleophilic substitution reactions at the imidoyl carbon have been investigated using chloride exchanges, Cl- + RY=CHCl right harpoon over left harpoon RY=CHCl + Cl- with Y = N and R = F, H or CH3, at the MP2, B3LYP and G2(+) levels using the MP2/6-311+G geometries. The results are compared with those for the vinyl (Y = CH) and carbonyl (Y = O) carbon substitution. The mechanism and reactivity of substitution at the imidoyl carbon are intermediate between those of carbonyl (SNpi) and vinyl carbon (SNsigma) substitution, which is directly related to the electronegativity of Y, CH < N < O. The prediction of competitive SNsigma with SNpi path for the imidoyl chloride is consistent with the S(N)1-like mechanism proposed for reactions in solution. The important factors in favor of an in-plane concerted SN2 (SNsigma) over an out-of-plane pi-attack (SNpi) path are (i) lower proximate sigma-sigma* charge-transfer energies (DeltaECT), (ii) stronger electrostatic stabilization (DeltaENCT), and (iii) larger lobe size on C(alpha) for the sigma*- than pi*-LUMO despite the higher sigma* than pi* level. The electron correlation energy effects at the MP2 level are overestimated for the relatively delocalized structure (S(N)pi TS) but are underestimated for the localized structure (SNsigma TS) so that the MP2 energies lead to a wrong prediction of preferred reaction path for the vinyl chloride. The DFT at the B3LYP level predicts correct reaction pathways but overestimates the electron correlation effects.

Role of Arg163 in the N-glycosidase activity of neo-trichosanthin

Three mutant crystals of neo-trichosanthin (n-TCS), R163K, R163H and R163Q, were obtained by the hanging drop vapor diffusion method. Structure determination indicated that there are no significant differences between the mutants and n-TCS except in the active pocket. All of them were also soaked in sodium citrate buffer (pH 4. 5) containing 20% KCl and 10 mg/ml AMP. Structure determination suggests that in the active pocket of the crystals of R163K and R163H, parallel to the aromatic ring of Tyr70, each mutant possesses an adenine. The relationship between structure and function is discussed. Biochemical analysis reveals that the mutants R163K and R163H have N-glycosidase activity, while R163Q does not. This suggests that R163 is a crucial residue for the enzyme activity of n-TCS, and its role is providing proton.

Role of TYR70 in the N-glycosidase activity of neo-trichosanthin

Trichosanthin (TCS) is a type I ribosome-inactivating protein (RIP) which possesses rRNA N-glycosidase activity. TCS has long been used as an abortifacient in China. In recent years, its immunomodulatory, anti-tumor and anti-HIV properties have attracted more and more attention. An isoform of trichosanthin, neo-trichosanthin (n-TCS), has been cloned and expressed as recombinant protein. The biochemical studies revealed that n-TCS has virtually the same rRNA N-glycosidase activity as TCS. The crystal structure of n-TCS is similar to TCS. The crystal of Y70A n-TCS, the mutant of recombinant n-TCS, was soaked in sodium citrate buffer (pH 5.5) containing 25% KCl and AMP (10 mg/ml) prior to data collection. After structure determination and refinement, no electron density corresponding to adenine can be detected around the active pocket. Furthermore, the reaction products of Y70A n-TCS and AMP incubated at various reaction times were analyzed using HPLC. No adenine can be detected. These results suggest that Tyr70 is crucial to n-TCS for its substrate recognition, binding and perhaps N-glycosidase activity.

High voltage shock induced cellular electrophysiological effects: transient refractoriness and bimodal changes in action potential duration

The cellular electrophysiological effects of defibrillation shocks on the myocardium during ventricular fibrillation are not clear. The present study investigated the effects of high voltage shocks on membrane potentials of isolated guinea pig and pig papillary muscles during rapid activations simulating ventricular fibrillation. High voltage shocks induced an action potential with a prolonged duration, followed by a transient refractory state. Subsequent action potentials following this refractory state had shortened durations. The duration of the transient refractory state varied in proportion to shock intensity and stimulation rate, whether the shock was biphasic or monophasic. Shock induced prolonged depolarization was not a consistent finding and mainly observed with slow stimulation rates. In conclusion, high voltage shocks induce bimodal changes of the action potential duration associated with a transient refractory state during rapid activation. The rate dependency of this refractory state suggests that the duration of the shock induced refractory state may be longer in the fibrillating than the normal beating heart, and may contribute to successful defibrillation.

Effect of isoproterenol on accessory pathways without overt retrograde conduction

INTRODUCTION

Absence of overt retrograde accessory pathway conduction may be related to low resting sympathetic tone in patients with apparent unidirectional anterogradely conducting accessory pathways (UACAP).

METHODS AND RESULTS

To test this hypothesis, we studied the effect of isoproterenol on accessory pathway function and tachycardia induction in 18 patients (12 men and 6 women, ages 34 +/- 16 years [mean +/- SD]) with UACAP. After baseline study in the drug-free state, electrphysiologic testing was repeated during infusion of isoproterenol (0.5 to 1.5 micrograms/min, titrated to increase heart rate by 20%). Isoproterenol shortened the anterograde effective refractory period (398 +/- 117 vs 305 +/- 63 msec; P < 0.01; basic drive cycle length 600 msec) of the accessory pathway. However, retrograde accessory pathway conduction and atrioventricular reentrant tachycardia were exposed in only 3 (17%) patients by isoproterenol infusion. All 3 patients with retrograde accessory pathway revealed after isoproterenol had clinically documented tachycardia (supraventricular tachycardia in 2, atrial fibrillation in 1) during exercise, while none of the patients with persistent absence of retrograde accessory pathway conduction had this symptom.

CONCLUSIONS

We conclude that absence of overt retrograde conduction over accessory pathways may be related to low resting sympathetic tone in some individuals. Restoration of retrograde conduction with isoproterenol is unusual and most likely to be observed in patients with clinically documented paroxysmal supraventricular tachycardia related to exercise.

Ventriculoatrial conduction in patients with implantable cardioverter defibrillators: implications for tachycardia discrimination by dual chamber sensing

Incorporation of atrial electrograms in the tachycardia detection algorithm may improve tachyarrhythmia discrimination by ICDs but retrograde ventriculoatrial (VA) conduction over the AV node during ventricular tachyarrhythmia may be problematic. The present study analyzed VA conduction characteristics in 66 ICD patients who had evaluation of the VA conduction system by electrophysiological studies before implant. VA conduction was demonstrated in patients during ventricular decremental stimulation. Forty patients had inducible sustained monomorphic VT. The minimum cycle length maintaining 1:1 VA conduction during ventricular stimulation was longer than the cycle of VT in every patient (496 +/- 100 msec vs 320 +/- 81 msec; P < 0.01). Occasional VA conduction during VT was observed in five patients and one patient had 2:1 VA conduction during induced VT. No patient had 1:1 VA conduction during VT. We conclude that brisk VA conduction is uncommon and 1:1 VA conduction during VT is rare ICD recipients. VA conduction is unlikely to complicate the incorporation of atrial electrograms into tachyarrhythmia detection algorithms.

Limb-salvage for osteosarcoma

Limb-salvage surgery plays an important role in the treatment of osteosarcoma. Among 104 patients with osteosarcoma we managed from 1974 to 1993, 60 were treated with limb-salvage procedure. 44 patients with IIB tumor received adjuvant chemotherapy, and the five-year survival rate was 46.69%. The local recurrence rate of these 60 patients was 15%, the infection rate 11.7%, and the prosthetic mechanical complication was 13.3%. Our results suggest that limb-salvage procedures are not only possible but also can provide patients with better function.

The value of electrophysiologic testing in patients resuscitated from documented ventricular fibrillation

INTRODUCTION

Electrophysiologic testing is performed in patients resuscitated from ventricular fibrillation (VF) on the assumption that sustained monomorphic ventricular tachycardia (VT) may be a precursor to VF, with the former amenable to assessment by serial drug testing.

METHODS AND RESULTS

We assessed the usefulness of this strategy by analyzing clinical and electrophysiologic data of 42 survivors (29 men and 13 women; mean age 54 +/- 14 years) of VF without a reversible cause. All patients had VF documented on ECG and required defibrillation. Underlying heart diseases included coronary disease in 28, dilated cardiomyopathy in 3, arrhythmogenic right ventricular dysplasia in 1, and no apparent structural heart disease in 10 patients. Only 2 (4.7%) patients had a prior history of documented VT. The electrophysiologic study was performed 7 to 30 days after VF. Programmed stimulation at the right ventricular apex using at least two drive cycle lengths and up to three extrastimuli induced sustained monomorphic VT in 4 (9.5%), sustained polymorphic VT in 3 (7.1%), nonsustained monomorphic VT in 1 (2.3%), nonsustained polymorphic VT in 5 (11.9%), and VF in 13 (30.9%) patients. Two patients with documented prior VT and coronary disease had sustained VT induced during the electrophysiologic study. On the other hand, sustained monomorphic VT was induced in 53 of the 59 (90%) patients (45 men and 14 women; mean age 57 +/- 16 years) with clinically documented VT concurrently studied using the same stimulation protocol.

CONCLUSION

We conclude that reproducible induction of sustained monomorphic VT in survivors of documented VF is uncommon. It may be more cost effective to proceed directly to treatment with implantable cardioverter defibrillators in these patients.

Fatigue phenomenon in accessory pathways

Fatigue phenomenon is transient failure of conduction following a period of repetitive excitation. Fatigue in accessory pathways is uncommon, and its electrophysiologic characteristics and clinical implications are unknown. Among the 215 patients who underwent electrophysiology studies from July 1992 to December 1993, 4 (2%) were found to exhibit fatigue over accessory pathways. The accessory pathway was posteroseptal in three patients and right free wall in one patient. The mean anterograde effective refractory period of the accessory pathway was 295 +/- 26 msec (range 270 to 330, basic drive cycle length 600 msec). Three patients had neither retrograde accessory pathway conduction nor inducible tachycardia even with infusion of isoproterenol. The fatigue phenomenon was observed after both atrial and ventricular stimulation in three patients and only after ventricular stimulation in one patient. Fatigue was dependent on duration more than rate of stimulation. We conclude that pathways exhibiting fatigue have a low margin of safety for conduction and are unlikely to be clinically problematic.

Effect of shock timing on efficacy and safety of internal cardioversion for ventricular tachycardia

OBJECTIVES

We examined the effect of shock timing within the QRS complex on cardioversion efficacy in a randomized crossover test of shocks delivered at two timing intervals relative to QRS onset.

BACKGROUND

The local ventricular electrogram is used in implantable cardioverter-defibrillators to synchronize cardioversion shocks to terminate ventricular tachycardia. However, the timing of the local electrogram relative to global ventricular depolarization is variable, depending on the site of ventricular tachycardia origin.

METHODS

Transvenous defibrillation leads were positioned in the right ventricular apex (cathode), coronary sinus and superior vena cava (anodes) of patients with sustained monomorphic ventricular tachycardia. After repeat ventricular tachycardia induction, sequential shocks with energy settings of 0.5 to 22 J were delivered simultaneously with QRS onset (QRS + 0 shock) or 100 ms after QRS onset (QRS + 100 shock). QRS onset was determined from the surface electrocardiogram. Cardioversion threshold, defined as the lowest shock energy for successful ventricular tachycardia termination, was measured for these two timings.

RESULTS

Fifteen patients (13 men, 2 women; mean [+/- SD] age 60.5 +/- 7.7 years) completed testing. Cardioversion threshold was significantly lower with QRS + 100 shocks than QRS + 0 shocks (3.1 +/- 3.5 vs. 10.5 +/- 7.4 J, p < 0.01). Thirteen patients (87%) experienced ventricular tachycardia acceleration with QRS + 0 shocks, but only three patients (20%) had ventricular tachycardia acceleration using QRS + 100 shocks (p < 0.01). Of the 32 failed QRS + 0 shocks, 25 (78%) caused ventricular tachycardia acceleration, whereas only 5 (36%) of the 14 failed QRS + 100 shocks caused ventricular tachycardia acceleration (p < 0.05). Cardioversion threshold was not correlated with ventricular tachycardia cycle length, QRS duration, left ventricular ejection fraction or left ventricular diastolic volume (p = NS).

CONCLUSIONS

Internal cardioversion shocks delivered late in the QRS complex during ventricular tachycardia are more effective and have a lower risk of ventricular tachycardia acceleration than those delivered near QRS onset.

Effect of adenosine or adenosine triphosphate on antidromic tachycardia

OBJECTIVES

This study was designed to determine the effect of adenosine or adenosine triphosphate (ATP) on antidromic tachycardia.

BACKGROUND

Adenosine and adenosine triphosphate are useful for differential diagnosis of wide QRS tachycardia. It has been believed that tachycardia termination caused by these agents is due to the preferential depressive effect on the atrioventricular (AV) node, whereas their effect on accessory pathways is minimal.

METHODS

We studied the effect of adenosine or ATP on the termination pattern of antidromic tachycardia in 17 patients (10 men, 7 women; mean age [+/- SD] 32 +/- 11 years) with one or more accessory pathways. Adenosine (6 to 12 mg [n = 10]) or ATP (8 to 20 mg [n = 7]) was injected rapidly through a central venous line and followed by 10 ml of saline flush after induction of sustained antidromic tachycardia.

RESULTS

Tachycardia was terminated in < 2 min in 14 patients (82%) after the injection and remained unchanged in 3 (18%). Tachycardia termination was due to conduction block in the accessory pathway (anterograde limb) in seven patients (50%) and in the AV node (retrograde limb) in another seven. Adenosine or ATP caused accessory pathway block in seven (88%) of the eight patients lacking retrograde accessory pathway conduction and in none of the nine patients having retrograde accessory pathway conduction (p < 0.01). All five patients with an atriofascicular accessory pathway and unidirectional anterograde conduction had tachycardia termination due to anterograde accessory pathway block after injection of adenosine or ATP.

CONCLUSIONS

1) Adenosine or ATP effectively terminates antidromic tachycardia; 2) the termination is related to block in either the accessory pathway or the AV node; 3) accessory pathway block occurs in patients with a unidirectional, anterogradely conducting accessory pathway, especially an atriofascicular accessory pathway.

Nonreentrant supraventricular tachycardia due to simultaneous conduction over fast and slow AV node pathways: successful treatment with radiofrequency ablation

A 55-year-old woman with frequent problematic supraventricular tachycardia is presented. The tachycardia was irregular with predominantly normal QRS morphology and was refractory to multiple antiarrhythmic drugs. At electrophysiology study, the tachycardia was inducible with atrial or ventricular extrastimuli and dual pathways were observed. In contrast to the situation usually seen with dual atrioventricular node physiology, the slow pathway had a longer effective refractory period than the fast pathway and reentrant tachycardia was not induced. Simultaneous conduction over the fast and slow pathways during sinus rhythm was shown to be the mechanism for clinical tachycardia. The tachycardia was successfully treated using radiofrequency ablation of the slow pathway.

[Fast neutron treatment of osteosarcoma]

Twelve patients with advanced osteosarcoma were treated with fast neutron at the Neutron Therapy Facility, the Hight-Energy Physics Institute, Chinese Academy of Science. Of the 12 patients, 5 were operated after radiotherapy. Three of them received fast neutron alone, and the other 2 with added 60Co. The doses ranged from 660 NcGy to 2 168 NcGy. Pain was relieved and the tumor size decreased in all the treated patients. Only one case was found histologically free of viable tumor cells. Skin reaction was serious and the knee joint function was impaired in all patients.

Radiofrequency catheter ablation of accessory pathways during entrainment of AV reentrant tachycardia

Radiofrequency ablation of accessory pathways must sometimes be done during orthodromic atrioventricular reentrant tachycardia when manifest anterograde accessory pathway conduction is absent or retrograde fusion obscures accessory pathway location during ventricular pacing. Unfortunately, abrupt heart rate slowing upon radiofrequency induced termination of atrioventricular reentrant tachycardia often causes catheter dislodgment. We report our experience in circumventing this problem during radiofrequency ablation by using entrainment of atrioventricular reentrant tachycardia. The latter maintains retrograde activation pattern over the accessory pathway while preventing abrupt ventricular rate change. Eight patients (4 men and 4 women, mean age 37.3 +/- 17.9) with eleven left-sided accessory pathways were included. Ablation during entrainment was used as the first approach in three patients with concealed accessory pathways and one patient with a bidirectional accessory pathway. In another four patients, ablation during entrainment was used after technical difficulties in ablating during tachycardia. Only 1-3 radiofrequency applications were required to eliminate the accessory pathway using the entrainment technique. The catheter remained stable when accessory pathway conduction was interrupted by radiofrequency current. In conclusion, entrainment of atrioventricular reentrant tachycardia during radiofrequency application is useful for maintaining catheter position for accessory pathway ablation during atrioventricular reentrant tachycardia.

Elimination of slow pathway conduction: an accurate indicator of clinical success after radiofrequency atrioventricular node modification

OBJECTIVES

The purpose of this study was to determine the optimal end point of radiofrequency atrioventricular (AV) node modification using anatomically guided slow pathway approaches in patients with AV node reentrant tachycardia.

BACKGROUND

The optimal end point for AV node modification using radiofrequency energy is uncertain, although elimination of inducible AV node reentrant tachycardia has been used.

METHODS

We followed up 51 consecutive patients (40 women, 11 men, mean age +/- SD 41 +/- 16 years) with symptomatic AV node reentrant tachycardia for 12 +/- 6 months (range 4 to 24) after radiofrequency AV node modification using an anatomically guided slow pathway approach. Inducible AV node reentrant tachycardia was eliminated in all patients, whereas residual slow pathway conduction persisted in 12 patients (24%) after ablation. One study was complicated by complete AV block and two patients were lost to follow-up (one with and one without residual slow pathway conduction).

RESULTS

Clinical recurrence of AV node reentrant tachycardia was documented in seven patients (14%) 3 days to 3 months (median 1 month) after ablation. The recurrence rate was significantly higher in patients with than in those without residual slow pathway conduction (6 [55%] of 11 vs. 1 [3%] of 37, p < 0.01). The recurrence rate was not different between patients with only residual slow pathway conduction and those with residual slow pathway conduction and inducible single echo cycles (three [60%] of five in both groups, p = NS). The number of radiofrequency energy applications was not significantly different between those without and those with recurrence (20 +/- 17 vs. 16 +/- 9, p = NS). Junctional tachycardia during application of radiofrequency energy tended to be more frequently observed in those with a successful outcome (77% vs. 57%, p > 0.05). Of the 22 patients who underwent modification before 1992, residual slow pathway conduction was present in 9 (41%) of 22 patients. Atrioventricular node reentrant tachycardia recurred in five (56%) of these nine patients. A greater effort made in 1992 to eliminate slow pathway conduction in 29 patients resulted in residual slow pathway conduction in only 3 (11%) with recurrence in 2 (4%).

CONCLUSIONS

Complete elimination of slow pathway conduction is feasible in the majority of patients. Elimination of slow pathway conduction is highly predictive of long-term success after AV node modification using an anatomically guided approach.

[Detection of RB gene in osteosarcoma by PCR]

We have established a stable PCR system and studied the structural anomalies of RB gene by it in osteosarcoma, previous studies have proved that 13-17 exons of RB gene are the deletion hotpoints. We designed a pair of perimers, RB1, RB2 stretching across 14-16 exons and studied 10 cases of osteosarcoma. No structural anomaly was found in the leucocyte. Two cases (20%) showed no PCR product. This result demonstrates for the first time the deletion of RB gene is present in Chinese osteosarcoma patients.

Arrhythmogenic effects of catecholamines are decreased in heart failure induced by rapid pacing in dogs

Increased circulating catecholamines are considered to be arrhythmogenic in heart failure. It is unclear whether increased circulating catecholamines contribute directly to ventricular arrhythmias or are only markers of the severity of heart failure. The present study determined the sensitivity of the failing heart to the arrhythmogenic effect of exogenous norepinephrine in a rapid pacing-induced model of heart failure in dogs (240 beats for 4 wk, n = 14). A similarly operated, non-paced group served as controls (n = 9). Cardiac sensitivity to the arrhythmogenic effect of catecholamines was determined by measuring the minimal dose of exogenous norepinephrine that induced ventricular tachycardia (arrhythmogenic threshold dose, ATD). ATD significantly increased after development of heart failure in heart-failure group (1.62 +/- 0.32 microgram/kg at baseline vs. 16.65 +/- 3.48 micrograms/kg at restudy, P < 0.01), whereas no significant change was noted in the control group (1.08 +/- 0.36 microgram/kg at baseline vs. 2.53 +/- 0.36 micrograms/kg at restudy, P > 0.10). Action potential duration was unchanged by superfusion with 10(-7) M isoproterenol in both ventricular muscles (230.2 +/- 6.1 vs. 229.7 +/- 5.3 ms, P = NS) and Purkinje fibers (273.2 +/- 6.5 vs. 283.8 +/- 4.2 ms, P = NS) from the failing hearts, although isoproterenol induced a shortening in the control group (204.8 +/- 0.9 vs. 181.3 +/- 1.6 ms in ventricular muscles, P < 0.01; 313.8 +/- 6.5 vs. 279.5 +/- 5.7 ms in Purkinje fibers, P < 0.01). We conclude that the failing heart has a decreased sensitivity to the arrhythmogenic effect of catecholamines.

Defibrillation shocks produce different effects on Purkinje fibers and ventricular muscle: implications for successful defibrillation, refibrillation and postshock arrhythmia

OBJECTIVES

To understand the mechanisms of postdefibrillation arrhythmias and failed defibrillation, we studied the cellular effects of high voltage shocks on different cardiomyocytes in the dog.

BACKGROUND

The causes of postdefibrillation arrhythmias and unsuccessful defibrillation are not clear.

METHODS

High voltage shocks with voltage differentials of 9.3 to 97.6 V/cm were delivered to isolated canine papillary muscles with attached Purkinje fibers. Transmembrane potentials were recorded simultaneously from the Purkinje fiber and the ventricular muscle using standard microelectrode techniques.

RESULTS

After delivery of high voltage shocks, significant depolarization and rapid firing were observed in Purkinje fibers. The maximal rate of the rapid firing in the Purkinje fibers correlated with shock intensity (r = 0.69, p < 0.05). In contrast, in ventricular muscle, only slight depolarization and a transient refractory state were observed after the shock. The incidence of the refractory state was correlated with both the shock intensity and the rate of the rapid firing in the Purkinje fiber (r = 0.89 and 0.74, p < 0.01 and 0.05, respectively). Propranolol at a concentration sufficient for complete beta-blockade (1 mg/liter) did not change the tissue response to shocks but suppressed or abolished the shock-induced rapid firing of Purkinje fibers at a higher concentration (3 mg/liter). Blockade of the slow calcium channel with verapamil (400 micrograms/dl) did not alter the responsiveness of the preparation to shocks.

CONCLUSION

These results indicate that high voltage shocks induce different responses in Purkinje fibers and ventricular muscle. The shock-induced rapid firing in the Purkinje fiber may contribute to postshock arrhythmias and possibly refibrillation in some cases. The shock-induced transient refractory state in the ventricular muscle may prevent the ventricle from responding to the rapid firing and thus may decrease the incidence of postshock arrhythmias.

Association between HLA antigens and families with psoriasis vulgaris

This paper typed HLA-A, B, C and DR antigens in patients with psoriasis vulgaris and healthy persons in 12 families. The phenotype frequencies of HLA-A1, B13, B17, Cw4 and Cw6 in the patients were higher than those in the controls. The analysis of haplotype segregation showed that HLA haplotypes in families with more psoriatic cases were marked deviation from random distribution. One or two HLA haplotypes sharing among affected siblings occurred more frequently than expected. The result of Lods score for six families showed that there was a close linkage between the gene of psoriasis vulgaris and HLA antigens. The gene of psoriasis was coincided with the recessive hereditary mode.

Electrophysiologic substrate associated with pacing-induced heart failure in dogs: potential value of programmed stimulation in predicting sudden death

To investigate the possible mechanisms of sudden death and the potential role of electrophysiologic testing in congestive heart failure, this study evaluated the electrophysiologic substrate in a model of heart failure induced by rapid pacing. Seventeen mongrel dogs underwent cardiac pacing at 220 to 240 beats/min for 5 weeks (paced group) and 11 other dogs served as a sham-operated control group. Rapid pacing of the right ventricle produced clinical and hemodynamic features of congestive heart failure. Dogs in the paced group had prolonged cardiac conduction time as reflected by longer epicardial activation time (36.1 +/- 2.4 vs. 30.8 +/- 0.8 ms, p less than 0.05). The ventricular effective refractory period was significantly prolonged after the development of heart failure (141 +/- 4 vs. 177 +/- 5 ms, p less than 0.01, at a basic pacing cycle length of 300 ms), whereas no significant change was found in the control group (140 +/- 4 vs. 145 +/- 4 ms, p = NS). The prolongation of the ventricular effective refractory period correlated with an increase in left ventricular end-diastolic pressure (r = 0.55, p less than 0.001) and the ventricular effective refractory period correlated inversely with cardiac index (r = -0.49, p less than 0.025). The rest membrane potential of ventricular muscle was less negative in the paced group compared with the control group (-80.7 +/- 2.2 vs. -85.6 +/- 2.2 mV, p less than 0.05). Intracellularly recorded action potential duration of ventricular muscle was longer in the paced than in the control group (236 +/- 9.8 vs. 198.9 +/- 2.6 ms, p less than 0.01), action potential duration at 90% repolarization).(ABSTRACT TRUNCATED AT 250 WORDS)

Defibrillation shocks increase myocardial pacing threshold: an intracellular microelectrode study

Defibrillation is known to cause inability to pace the heart acutely, but the mechanism is unknown. This study used microelectrode techniques to directly evaluate the effect of defibrillation shocks on the pacing threshold and membrane potentials from superfused guinea pig papillary muscles. Failure of pacing stimuli to induce action potentials (pacing failure) followed shocks of 50-200 V/cm, with pacing failure duration correlated with shock intensity. Increasing pacing strength from one to three times diastolic threshold decreased the incidence and duration of pacing failure. Decreased extracellular calcium concentration and verapamil added to the superfusate increased the duration of pacing failure. Membrane potential depolarization occurred after shock, but pacing failure did not correlate with depolarization magnitude. We conclude that defibrillation shocks directly cause shock intensity-dependent increase of myocardial pacing threshold. The pacing threshold of the myocardium can be increased after defibrillation shock independent of hypoxia or shock-induced depolarization and may involve membrane changes in calcium handling.

DNA fragments of Bombyx mori nuclear polyhedrosis virus containing the promoters active in prokaryotes

Using a promoter probe plasmid in E. coli called pHE5, eight different HindIII and one SalI DNA fragments of Bombyx mori nuclear polyhedrosis virus, directing the expression of the tetracycline resistance gene, have been cloned and isolated. The tetracycline resistance levels of the strains containing the recombinant plasmids were measured. Among them, the highest level of the resistance to tetracycline was 30 micrograms/ml. Part of the nucleotide sequence of a DNA fragment was determined. A sequence similar to the E. coli promoter was found.