[The effects of stelleta ganglion resection on heart failure in response to pressure overload].

Objective: To observe the impact and difference of resection of left stellate ganglion (LSG) or right stellate ganglion (RSG) on rats with heart failure. Methods: Thirty male SD rats were divided into 3 groups (n=10 each) by random number table method: control group, LSG group, RSG group. All three groups underwent TAC surgery to establish a pressure-overloaded heart failure model. Then, LSG and RSG were bluntly separated and removed in rats assigned to the LSG group or RSG group by surgery, while rats in the control group underwent sham operation. The changes in blood pressure and heart rate before operation, 30 minutes and 10 weeks after operation were recorded; echocardiography was performed before operation and 10 weeks after operation to detect the thickness of the ventricular septum, left ventricle posterior wall diameter, left ventricular end diastolic diameter, left ventricular end diastolic volume, and calculate the left ventricular fractional shortening and left ventricular ejection fraction. HE staining and Masson staining were performed to observe the degree of myocardial hypertrophy and myocardial fibrosis, and to judge the ventricular remodeling. Results: The heart rates of the three groups of rats were (352.4±4.3), (320.3±4.0) and (297.9±5.9) beats/min, and the blood pressure was (142.8±2.3), (123.4±2.7) and (129.6±2.9) mmHg(1 mmHg=0.133 kPa) at thirty minutes after surgery; the heart rates of the three groups of rats were (352.9±4.0), (321.6±3.4) and (301±4.1) beats/min, and the blood pressure was (145.6±1.9), (124.8±1.7) and (130.4±4.4) mmHg at 10 weeks after surgery. The heart rate and blood pressure in the LSG group and RSG group at 30 min and 10 weeks after surgery were significantly lower than those in the control group; at 10 weeks after surgery, the heart rate in the RSG group was significantly lower than that in the LSG group (P both<0.001). After 10 weeks, rats in the control group developed severe left ventricular dilatation. Degree of left ventricular hypertrophy was significantly reduced in the LSG group and RSG group than in the control group, the thickness of the ventricular septum was (3.2±0.3), (2.5±0.1) and (2.5±0.1) mm; the left ventricular end-diastolic diameters were (7.5±0.3), (5.5±0.3) and (5.7±0.2) mm; the left ventricular end-diastolic volume was (9.5±0.3), (4.5±0.2) and (4.8±0.2) ml; the left ventricular fractional shortening was (21.6±1.3)%, (49.1±3.9)% and (47.4±1.5)%; and the left ventricular ejection fraction was (50.9±2.5)%, (81.9±2.1)% and (80.0±2.3)%, respectively in the control group, LSG group and RSG group. Compared with the control group, the left ventricular posterior wall diameter, left ventricular end-diastolic diameter and left ventricular end-diastolic volume were significantly lower and the left ventricular fractional shortening and left ventricular ejection fraction were significantly higher in the LSG group and RSG group (all P<0.001). 10 weeks after operation, the values of type Ⅰ collagen in the control group, LSG group, and RSG group were (0.354±0.013), (0.211±0.012) and (0.243±0.013), respectively. Ratio of type Ⅰ/Ⅲ collagen was (1.109±0.065), (0.737±0.055) and (0.839±0.075), respectively. Compared with the control group, the ratio of type Ⅰcollagen and ratio of type Ⅰ/Ⅲ collagen were significantly lower in the LSG group and RSG group (P<0.001). Conclusion: Both left and right stellate ganglion resection can similarly reduce ventricular remodeling caused by pressure overload and delay the progression of heart failure in tis TAC rat model.

[Clinical study of FibroTouch and six serological models for assessing the degree of liver fibrosis in patients with chronic hepatitis B].

Objective: To evaluate the using value of FibroTouch and six serological models in detecting the degree of liver fibrosis in patients with chronic hepatitis B, in an attempt to provide reference for accurate diagnosis. Methods: Two hundred and fifty-eight cases with chronic hepatitis B admitted to Xixi Hospital of Hangzhou from September 1, 2015 to September 1, 2017 were selected. All patients underwent liver histopathological examination and FibroTouch measurement to determine liver stiffness (LSM). Serum biochemical parameters were detected and the scoring values of six serological models were calculated. SAS 9.4 statistical software was used for statistical analysis, and the correlation between FibroTouch and the six serological models was analyzed by Spearman correlation. The diagnostic value of FibroTouch and six serological models was analyzed by receiver operating characteristic curve (ROC) based on liver histopathological findings. Results: The median LSM of 258 cases with chronic hepatitis B was 9.4 (6.5-13.8) kPa. In the six serological models, the median value of aspartate transaminase to platelet ratio index (APRI), FIB-4 index, S-index, Forn's index, PRPindex, and FIB-5 were 0.42 (0.28-0.62), 1.27 (0.78-2.03), 0.11 (0.07-0.20), 6.95 (5.89-8.51), 0.000 8 (0.000 6-0.000 9),and 38.59 (36.28-40.97). FibroTouch had positive correlation with APRI, FIB-4, S-index, Forn's index, PRP, fibrosis stage (r= 0.73,P< 0.001) and inflammation grade, and had negative correlation with FIB-5, and both had statistical significance. The area under curve (AUC) of FT-LSM at S≥2, S≥3, S = 4 were 0.89, 0.90 and 0.85, respectively, which was significantly higher than serological models (P< 0.001). The AUC of S-index model at S≥2, S≥3, S = 4 were higher than other five serological models. Conclusion: The diagnostic performance of FibroTouch is significantly better than serological model. S-index model has the best diagnostic performance in the six serological models, and the combination of S-index and FT-LSM may better diagnose the grading of liver fibrosis, and thus can be applied and promoted in clinic.

[Effect of α7nAChR mediated cholinergic anti-inflammatory pathway on inhibition of atrial fibrillation by low-level vagus nerve stimulation].

Objective: To investigate the effect of α7nAChR mediated cholinergic anti-inflammatory pathway on inhibition of atrial fibrillation by low-level vagus nerve stimulation(LL-VNS). Methods: Eighteen beagles were randomized into control group (n=6), LL-VNS group (n=6) and methyllycaconitine (MLA) + LL-VNS group (n=6). All the beagles were subjected to rapid atrial pacing at 800 beats/min for 6 hours.And the effective refractory period (ERP) of atriums and pulmonary veins and induced atrial fibrillation (AF) were measured hourly during non-pacing.After cessation of pacing for 3 hours, the beagles in control group were injected with saline into four ganglionated plexis (GPs), the beagles in LL-VNS group were given LL-VNS and saline injected into four GPs, and the beagles in MLA+ LL-VNS group were injected with MLA into four GPs combined with LL-VNS.And the levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and acetylcholine (ACh) in the plasma at baseline condition, 3 h and 6 h were measured.At the end of this experiment, atrial tissues were collected to examine the levels of TNF-α, IL-6, ACh, NF-κBp65 and STAT3 proteins. Results: During the right atrium pacing for the first 3 hours, the ERPs were gradually decreased while AF inducibility were gradually increased in all groups. At the end of this experiment, compared with the control group and MLA+ LL-VNS group, the ERPs in LL-VNS group were increased, and the induced times and duration of AF were significantly decreased. The levels of TNF-α and IL-6 in plasma were all significantly decreased in LL-VNS group and MLA+ LL-VNS group when compared with the control group(pg/ml) [IL-6: (101±6) vs (119±7), P<0.05; (102±5) vs (119±7), P<0.05; TNF-α: (17.8±1.7) vs (22.1±2.0), P<0.05; (17.9±2.2) vs (22.1±2.0), P<0.05]. And the levels of ACh were higher than in the control group(µg/ml)[(151±13) vs (123±10), P<0.05; (145±5) vs (123±10), P<0.05]. After cessation of pacing for 6 hours, compared with the control groupand MLA+ LL-VNS group, the tissue levels of TNF-α and IL-6 were significantly decreased in LL-VNS group (P<0.05). The concentrations of NF-κBp65 proteins in atrial tissues were lower in the LL-VNS group (P<0.05), and the levels of STAT3 proteins in those tissues were higher in the LL-VNS group than in thein the two other groups (P<0.05). Conclusion: LL-VNS could inhibit the atrial electrical remodeling and atrial fibrillation induction; cholinergic anti-inflammatory pathway mediated by α7nAChR may be the important mechanism in vagal nerve regulated AF.

[Preparation of chaperone-antigen peptide vaccine derived from human gastric cancer stem cells and its immune function].

Objective: To explore the method of extracting chaperone antigen peptide complexes from gastric cancer stem cells and its immune function. Methods: Gastric cancer stem cells and gastric cancer cells were screened by low temperature ultrasonic lysis. After salting out and dialysis, the lysate supernatant was processed with SDS-PAGE to analyze the expression of chaperone antigen peptide complexes, and then was separated and purified with CNBr-activated SepharoseTM 4B. Reverse high pressure liquid chromatography (HPLC), SDS-PAGE and Western blotting were used to analyze the purity and nature of the acquired albumen. Lymphocyte proliferation assay and lymphocytotoxicity assay were used to ditermine the immunological activity of the chaperone-antigen peptide complexes. Results: The chaperone antigen peptide complexes of gastric cancer stem cells were prepared and identified successfully, of which the main components were the antigen peptides of HSP60, HSP70, HSP90 and HSP110. 0.75 µg and 1.00 µg HSP70-antigen peptide and 1.00 µg HSP90-antigen peptide activated lymphocytes significantly. Their A(490) values were 0.26±0.03, 0.45±0.05 and 0.32±0.04, respectively, while the corresponding doses of HSP60-antigen peptide and HSP110-antigen peptide did not activate lymphocytes. The killing rates of 1.00 µg HSP70-antigen peptide and 1.00 µg HSP70 were (45.0±2.0)% and (16.0±2.0)%, respectively, showing a significant difference (P=0.012). Similarly, the killing rates of 1.00 µg HSP90-antigen peptide and 1.00 µg HSP90 were (36.0±5.0)% and (13.0±4.0)%, respectively, also showing a significant difference (P=0.048). Conclusions: The amount of chaperone antigen peptide complexes in gastric cancer cells is extremely low, but it is obviously increased in gastric cancer stem cells. After purification, the chaperone antigen peptide complexes with high purity can be prepared. The extracted chaperone antigen peptide complexes have stronger immunogenicity, and can be used to make tumor vaccine in vitro, which may have a good application value in the targeted therapy of gastric cancer.

Reduction of galectin-3 expression reduces pituitary tumor cell progression.

We investigated the role of galectin 3 in the development and progression of pituitary tumors. We used RNA interference to depress Gal-3 gene expression; MTT and flow cytometry were applied to detect changes in cell proliferation and apoptosis levels in pituitary tumor cells. Expression of apoptosis-associated genes, Bcl-2 and Baxk was analyzed by Western blot. Inhibition of Gal-3 gene expression by RNA interference decreased GH3 cell proliferation and increased cell apoptosis; the expression levels of Gal-3 protein significantly decreased, along with those of Bcl-2, although Bax levels did not change. We conclude that Gal-3 has an important role in pituitary tumor cell proliferation and progression; and it may be useful as a target for the treatment of aggressive pituitary tumors.

Dietary inclusion level and time effects of taurine on broiler performance, meat quality, oxidative status and muscle taurine content.

Two experiments were conducted to investigate the effect of taurine on growth performance, meat quality, oxidative status and muscle taurine content in broilers. In Experiment 1, 50 one-day-old male Cobb chicks were given a diet supplemented with 0, 0.125, 0.50, 2.00 or 8.00 g/kg taurine from 1 to 42 d of age. In Experiment 2, 80 22-d-old male Cobb chicks were given a diet supplemented with 4.00 g/kg taurine for 0, 1, 2 or 3 weeks. Taurine contents of thigh and breast muscle increased linearly with increasing dietary taurine. Taurine supplementation for 1, 2 and 3 weeks significantly increased the taurine content of breast muscle. The taurine contents of liver and thigh meat were significantly increased by taurine supplementation for 3 weeks. The taurine contents of thigh and breast meat from broilers given a diet supplemented with 4 g/kg taurine for 3 weeks increased to 1.89 times the concentrations of the control group. There were no detrimental effects on growth performance, breast or thigh muscle yield, pH value or drip-water loss, and taurine supplementation did not affect the serum carbonyl content. Serum malondialdehyde concentration was significantly decreased by taurine supplementation for 1, 2 or 3 weeks.

Realization of a crosstalk-avoided quantum network node using dual-type qubits of the same ion species.

Generating ion-photon entanglement is a crucial step for scalable trapped-ion quantum networks. To avoid the crosstalk on memory qubits carrying quantum information, it is common to use a different ion species for ion-photon entanglement generation such that the scattered photons are far off-resonant for the memory qubits. However, such a dual-species scheme can be subject to inefficient sympathetic cooling due to the mass mismatch of the ions. Here we demonstrate a trapped-ion quantum network node in the dual-type qubit scheme where two types of qubits are encoded in the S and F hyperfine structure levels of 171Yb+ ions. We generate ion photon entanglement for the S-qubit in a typical timescale of hundreds of milliseconds, and verify its small crosstalk on a nearby F-qubit with coherence time above seconds. Our work demonstrates an enabling function of the dual-type qubit scheme for scalable quantum networks.

First Report of Root-Knot Nematode Meloidogyne arenaria Infesting Roots of Anubias barteri in Guangdong, China.

Anubias spp. are very popular aquatic plants that are native to Africa. Anubias barteri is a broadleaf Anubias and is a popular choice for aquariums because of its robust size. In China, broadleaf Anubias is usually planted in sand, with sponges around the rhizome, in small plastic baskets in aquatic plant nurseries. In December 2010, a survey of phytoparasitic nematodes was conducted in the nurseries in Guangzhou, Guangdong Province. Many second-stage juveniles of a Meloidogyne sp. were detected from the roots of A. barteri, but no root galls were found. To identify these juveniles, molecular identification was performed with PCR. The DNA sequence between CO II and l-rRNA of the mitochondrial gene of single juveniles was amplified with universal primers of Meloidogyne, #C2F3 (5'-GGTCAATGTTCAGAAATTTGTGG-3') and #1108 (5'-TACCTTTGACCAATCACGCT-3') (3). The amplified fragments were approximately 1.1 kb long and could not be digested with restrictive enzyme HinfI. The specific fragments were then sequenced. The blast search result revealed that the DNA sequence (GenBank Accession No. JQ446377) had 99 to 100% identity with submitted sequences of Meloidogyne arenaria (GenBank Accession Nos. EU364879, GQ266686, and AY635610). The other extracted juveniles were inoculated into sterile, potted, water spinach (Ipomoea aquatica) in the greenhouse to obtain more nematodes. After 40 days, root galls and female egg masses were clearly observed, and biochemical, molecular, and morphological identifications were conducted. Isoenzyme phenotype (esterase and malate dehydrogenase (MDH) patterns) and the perineal pattern of several gravid females were the same as M. arenaria (1,2), and PCR amplification of single juveniles produced identical fragments as previously found. Single egg masses were collected and juveniles were hatched out and inoculated onto 10 nematode-free plants of A. barteri in a greenhouse. After 40 days, roots of A. barteri exhibited inconspicuous small galls, and the same identification procedures were conducted as mentioned previously. Isoenzyme phenotypes, perineal patterns of adult females, and amplified fragments of single juveniles were identical to those of M. arenaria. M. arenaria is one of the most important root-knot nematodes and causes great losses in many crops around the world (2). To our knowledge, this is the first record of M. arenaria parasitizing aquatic plants of broadleaf Anubias in China and elsewhere, and A. barteri is a new host of M. arenaria. The economic importance of this nematode to A. barteri production is currently unknown. However, because A. barteri is a commercial aquatic plant, more attention should be given by producers to prevent this nematode from becoming an important pathogen. In addition, this finding is very helpful for relevant plant nematode quarantine work. References: (1) P. R. Esbenshade and A. C. Triantaphyllou. J. Nematol. 17:1, 1985. (2) R. N. Perry et al. Root-Knot Nematodes. CABI. Wallingford, UK, 2009. (3) T. O. Powers and T. S. Harris. J. Nematol. 25:1, 1993.

Impact of strain engineering on nanoscale strained InGaAs MOSFET devices.

The strain distributions in the In(0.53)Ga(0.47)As channel regions of the In(0.4)Ga(0.6)As source/drain (S/D) with various lengths and widths were studied via 3D process simulations. The resulting mobility improvement was analyzed. The tensile strain along the transport direction was found to dominate the mobility improvement. The strain along the vertical direction perpendicular to the gate oxide was found to affect the mobility the least, while the strain along the width direction was slightly degraded. The impact of the channel width and length on the performance improvement, such as on the mobility gain, was analyzed via TCAD simulations. The novelty of this paper stems from its study of the impact of the channel width and length on the performance of InGaAs NMOSFETs, such as on their mobility gain, and from its exploration of physical insights for scaling the future III-V MOS devices.

Impact of the nanorod structure on the tandem thin-film solar cell.

The novel thin-film solar cell was investigated with a nanorod structure that could solve the conflict between light absorption and carrier transport in the amorphous silicon (a-Si)/amorphous silicon-germanium (a-SiGe) tandem thin-film solar cell. This structure has an n-type a-Si nanorod array on the substrate, and an a-SiOx p-layer and an a-SiGe i-layer are sequentially grown along the surface of each n-type a-Si nanorod, for the bottom cell. After the above bottom-cell process, a similar process is used to fabricate an amorphous Si p-i-n top cell on the bottom cell. Under sunlight illumination, the light is absorbed along the vertical direction of the nanorod, but as the carrier transport is along the horizontal direction, the nanorod may absorb most of the sunlight. In the meantime, the solar cell is still thin enough for the effective transport of photogenerated carriers.

Thyroid hormone predisposes rabbits to atrial arrhythmias by shortening monophasic action period and effective refractory period: results from an in vivo study.

BACKGROUND: Atrial arrhythmias are common complications of hyperthyroidism, but the underlying mechanisms remain to be further clarified. Thus, in this study, we try to investigate the effects of thyroid hormone on atrial electrophysiology by using a hyperthyroidism model in vivo. MATERIALS AND METHODS: Twenty-four New Zealand white rabbits were randomized into Thyroxine group (no.=12) and Control group (no.=12). In Thyroxine group, Levo-thyroxine (L-T(4)) solution (1 mg/kg x d(-1)) was injected daily into the peritoneum for 2 weeks. In Control group, the same amount of saline was injected. On day 15, 8 rabbits in each group were chosen randomly to receive electrophysiological experiment in vivo, in which electrophysiological parameters and atrial arrhythmias induced by electrical stimulation were recorded and serum thyroid hormone levels were examined. The others were killed so as to exam the L-type calcium current of atrium. RESULTS: Atrial monophasic action potential at 90 repolarization (AMAP(90)) and effective refractory period (AERP) were significantly shorter in Thyroxine group than in Control group (AMAP(90): 103.21+/-1.94 vs 122.14+/-6.13, p<0.01; AERP: 82.69+/-0.99 vs 102.46+/-2.32, p<0.01). There are significant differences in the incidence of atrial arrhythmias between the two groups. The mean peak of L-type calcium current (I(Ca,L)) densities (pA/pF) at -10mV was significantly higher in Thyroxine group than in Control group (-8.59+/-0.68 vs -6.54+/-0.49, no.=8, p<0.001). CONCLUSIONS: In our hyperthyroidism model, thyroid hormone predisposed rabbits to atrial arrhythmias by shortening AMAP and AERP, which might be associated with increased I(Ca,L) current densities in atrium.

Natural killer cells suppress full cycle HCV infection of human hepatocytes.

The role of natural killer (NK) cells in controlling hepatitis C virus (HCV) infection and replication has not been fully delineated. We examined NK cell-mediated noncytolytic effect on full cycle HCV infection of human hepatocytes. Human hepatocytes (Huh7.5.1 cells) co-cultured with NK cells or treated with supernatants (SN) from NK cells cultures had significantly lower levels of HCV RNA and protein than control cells. This NK cell-mediated anti-HCV activity could be largely abolished by antibody to interferon-gamma (IFN-gamma). The investigation of the mechanisms for NK cell-mediated anti-HCV activity showed that NK SN-treated hepatocytes expressed higher levels of IFN-alpha/beta than the control cells. NK SN also enhanced IFN regulatory factor-3 and 7 expression in the hepatocytes. In addition, NK SN enhanced the expression of signal transducer and activator of transcription 1 and 2, the nuclear factors that are essential for the activation of IFN-mediated antiviral pathways. These data provide direct evidence at cellular and molecular levels that NK cells have a key role in suppressing HCV infection of and replication in human hepatocytes.

Relationship between brain activity and voiding patterns in healthy preterm neonates.

INTRODUCTION: It remains controversial as to whether the brain affects voiding control in preterm newborns. Constant bladder volume has previously been thought to induce bladder voiding in neonates, with no influence from the brain. Lately, there has been distinct evidence for an existing connection between the central nervous system and bladder voiding in preterm infants, as the voiding reflex arouses neonatal children. Video electroencephalography (EEG) is useful for recording bioelectrical activity of the cerebral cortex and exploring its relationship with voiding patterns in preterm neonates. OBJECTIVE: The objective was to investigate the relationship between voiding patterns and brain activity in healthy preterm neonates by using video-EEG. STUDY DESIGN: Forty-seven healthy preterm neonates (16 females) with a mean postconceptional age (PCA) of 34.1 ± 1.8 weeks were divided according to PCA into three groups: Group I (31-33 weeks, n = 13); Group II (33-35 weeks, n = 14); and Group III (35-37 weeks, n = 20). Video-EEG data from eight cortical regions were recorded from 08:00-12:00, along with 4-hour free voiding patterns and status at voiding (awake/sleep). RESULTS: In Group I, the voiding frequency (VF) was significantly higher and the voiding volume (VV) was significantly lower than in the other groups. There were no significant differences in bladder capacity (BC), bladder capacity/birth weight (BC/BW), postvoiding residual/bladder capacity (PVR/BC), or urinary flow rate (UFR) among the three groups. The Fp1-T3 and Fp2-T4 lead amplitudes significantly differed in Group I and Group II at 5 s before (pre-5), during, and after voiding (post-5). The Fp2-C4 total and theta band lead amplitudes significantly differed across all urination states among the groups. There were no significant differences in electroencephalography frequency among the groups in any urination state. DISCUSSION: There were no significant differences in BC, BC/BW, PVR/BC, or UFR among the three groups, indicating slow bladder function development in preterm neonates. In this study, the EEG amplitude changed in certain pairs of electrodes. These changes might indicate the degree of bladder sensor maturation along with an increasing PCA. This study further suggests that the brain changes in preterm neonates during quiet sleep voiding prominently occur in the right prefrontal cortex and central region. CONCLUSIONS: In preterm neonates, bladder voiding during quiet sleep was accompanied by cortical arousal that might have emanated from a lower center.

Loss of expression of death-inducing signaling complex (DISC) components in lung cancer cell lines and the influence of MYC amplification.

We have previously reported that the key apoptosis related gene caspase 8 (CASP8) is frequently silenced in small cell lung cancer (SCLC) tumors and cell lines usually, but not always, by aberrant promoter methylation. Because CASP8 is a key component of the death-inducing signaling complex (DISC) when specific death receptors (including DR4, DR5, FAS) are activated by their specific ligands (TRAIL/FASL), we examined expression of the components of the DISC complex in lung cancer cell lines. MYC family members are frequently amplified (MYC+ve) in SCLC, and MYC is a potent inducer of apoptosis. We examined 34 SCLC lines (12 of which were MYC+ve) and 22 NSCLC lines. CASP8 gene expression was frequently lost (79%) at message and protein levels in SCLC but not in non-SCLC (NSCLC). MYC amplification was present in 45% of SCLC cell lines, which had lost CASP8 expression, but not in any of the CASP8 positive lines. The frequency of CASP8 loss was significantly higher in MYC+ve SCLC compared to MYC-ve SCLC or in NSCLC. Analyses of other DISC components showed significantly higher rates of loss of expression of CASP10, DR5, FAS and FASL in SCLC compared to NSCLC. The loss of expression of proapoptotic DISC components was significantly higher in MYC+ve SCLC cell lines and these lines were completely resistant to TRAIL. Expression of CASP10 (a caspase closely related to CASP8) was frequently absent at the protein level in both SCLC and NSCLC lines. Expression of c-FLIP (proteolytically inactive homolog of CASP8) was inversely related to expression of CASP8. Our major conclusions are: (a) The death receptor pathway is differently inactivated at multiple levels in lung cancer cell lines; and (b) MYC amplification in SCLC is associated with inactivation of most components of the DISC complex, with resistance to TRAIL and with expression of c-FLIP. These findings may have considerable clinical and therapeutic implications.

Aberrant methylation of the adenomatous polyposis coli (APC) gene promoter 1A in breast and lung carcinomas.

The adenomatous polyposis coli (APC) gene is a tumor suppressor gene associated with both familial and sporadic cancer. Despite high rates of allelic loss in lung and breast cancers, point mutations of the APC gene are infrequent in these cancer types. Aberrant methylation of the APC promoter 1A occurs in some colorectal and gastric malignancies, and we investigated whether the same mechanism occurs in lung and breast cancers. The methylation status of the APC gene promoter 1A was analyzed in 77 breast, 50 small cell (SCLC), and 106 non-small cell (NSCLC) lung cancer tumors and cell lines and in 68 nonmalignant tissues by methylation-specific PCR. Expression of the APC promoter 1A transcript was examined in a subset of cell lines by reverse transcription-PCR, and loss of heterozygosity at the gene locus was analyzed by the use of 12 microsatellite and polymorphic markers. Statistical tests were two-sided. Promoter 1A was methylated in 34 of 77 breast cancer tumors and cell lines (44%), in 56 of 106 NSCLC tumors and cell lines (53%), in 13 of 50 SCLC cell lines (26%), and in 3 of 68 nonmalignant samples (4%). Most cell lines tested contained the unmethylated or methylated form exclusively. In 27 cell lines tested, there was complete concordance between promoter methylation and silencing of its transcript. Demethylation with 5-aza-2'-deoxycytidine treatment restored transcript 1A expression in all eight methylated cell lines tested. Loss of heterozygosity at the APC locus was observed in 85% of SCLCs, 83% of NSCLCs, and 63% of breast cancer cell lines. The frequency of methylation in breast cancers increased with tumor stage and size. In summary, aberrant methylation of the 1A promoter of the APC gene and loss of its specific transcript is frequently present in breast and NSCLC cancers and cell lines and, to a lesser extent, in SCLC cell lines. Our findings may be of biological and clinical importance.

Daily embolism and refilling of xylem vessels in the roots of field-grown maize.

Embolisms in the vessels of maize axile roots of different types were observed directly after rapid freezing of intact, functioning roots in the field, by cryo-scanning electron microscopy. Quantification of the degree of embolization in each root was made by counting empty and full vessels of both the late and early metaxylem (LMX & EMX), and expressed as percent embolized vessels of the LMX, and %EMX poles containing embolized vessels. Contents of the connecting xylem (CX) at branch root junctions, and of xylem in branch roots were observed also, but not systematically quantified. Records of % embolized vessels were made from dawn to dusk on summer days in Ottawa under moderate irradiance, and in Canberra under high irradiance. Measurements in Canberra were supported by estimates of irradiance, of stomatal conductance, and of chamber balance pressure of bagged and unbagged leaves. Soon after sunrise embolisms appeared in all types of vessel, at balance pressures c. 300-400 kPa, and increased rapidly with increasing irradiance. During the middle of the day % embolized vessels reached a maximum (LMX ≈70% in Ottawa, and ≈80% in Canberra). At all times the EMX vessels were less embolized. The midday maximum was brief in Ottawa, and % embolized vessels fell to a low value during the afternoon. In Canberra the maximum was prolonged into late afternoon. By dusk nearly all vessels were once again filled with sap. The balance pressures measured during vessel refilling in Canberra ranged from 500 kPa to 1200 kPa. At all times of the day sap was seen entering some embolized vessels. Almost all were refilling by mid- to late-afternoon. Such refilling was especially frequent at junctions of branch roots with the axile roots. X-ray microanalysis of the sap entering the vessels, and of the liquid filling or partly filling vessels, showed the concentration of mineral solutes present in the sap was below the threshold of detection (≈12 mM). These results are discussed in relation to current opinions about embolisms and vessel refilling.

Location and quantification of phosphorus and other elements in fully hydrated, soil-grown arbuscular mycorrhizas: a cryo-analytical scanning electron microscopy study.

• Concentrations of phosphorus (P), potassium (K), magnesium (Mg) and calcium (Ca) were determined in situ in fully hydrated arbuscular mycorrhizas by cryo-analytical scanning electron microscopy. The field- and glasshouse-grown plants (subterranean and white clovers, field pea and leek) were colonized by indigenous mycorrhizal fungi. • The [P] in intraradical hyphae was generally 60-170 mM, although up to 600 mM was recorded, and formed strong linear relationships with [K], up to 350 mM, and [Mg], up to 175 mM. Little Ca was detected. The turgid branches of young arbuscules contained 30-50 mM P, up to 100 mM K and little Mg. Collapsing arbuscule branches and clumped arbuscules had greatly elevated Ca (30-250 mM), but otherwise differed little from young arbuscule branches in elemental concentration. • The [P] was low or undetectable in 86% of uncolonized cortical cell vacuoles, but was generally elevated in vacuoles surrounding an arbuscule and in the liquid surrounding hyphae in intercellular spaces. • Our results suggest that both young arbuscules and intercellular hyphae are sites for P-transfer, that Mg2+ and K+ are probably balancing cations for P anions in hyphae, and that host cells may limit arbuscule lifespan through deposition of material rich in Ca.

Planing frozen hydrated plant specimens for SEM observation and EDX microanalysis.

A procedure is described for forming a flat face on a frozen piece of plant tissue, which may then be observed fully-hydrated or lightly etched, and coated or uncoated with a metal film, in scanning electron microscopy (SEM). The frozen sample was planed with a glass knife at -80 degrees C in a cryo-ultramicrotome. The sections were discarded, and the planed block face placed on the cold stage in the microscope column, either for observation uncoated at low kV, or for light etching (-90 degrees C) to reveal the cell outlines. If a higher accelerating voltage was needed, the face was given an evaporative coating of Al in the cryo-preparation chamber and returned to the column. The advantages of the planed face over the usual fracture face are illustrated: imaging at a chosen rather than a chance position; clearer cellular and subcellular detail; preservation of hydrated gels like mucilage and swollen cell walls; the possibility of making serial parallel sections through the same piece of tissue; opportunities for accurate morphometric analyses on the planed face; capacity to produce longitudinal sections; preservation of very delicate structures that are destroyed by fixation and drying. A major advantage of the Al-coated planed face is the increased accuracy of energy-dispersive X-ray (EDX) microanalyses on a smooth rather than a rough surface. Tests are included which show that neither the light etching employed, nor successive planing, interferes with the analyses of elements in the frozen face.