[Clinical value of arterial stiffness assessment on risk prediction of vascular stiffness in the octogenarian elderly].

Objective: This study aimed to analyze clinical factors related to arterial stiffening and establish a risk prediction nomogram of arterial stiffening in the octogenarian(≥80 years). Methods: This study was a retrospective cross-sectional study, which enrolled the octogenarian elderly who underwent physical examination and secondary prevention intervention in the outpatient department of Chinese People's Liberation Army General Hospital from April 2022 to August 2022. Clinical data including demographics, biochemical indicators and medical history were collected. Brachial-ankle pulse wave velocity (baPWV) was detected during the clinical visit. Participants were divided into the control group (baPWV≤1 800 cm/s) and vascular sclerosis group (baPWV>1 800 cm/s). The risk factors of arterial stiffness were analyzed by univariate and logistic regression analysis, and the nomogram model was constructed by R programming language. The predictive effect of the nomogram model was evaluated by the receiver operating characteristic curve (ROC). Results: The median age of the 525 participants was 87.0 (82.0, 92.0) years, 504 (96.0%) were male, 82 in the control group, 443 in the vascular sclerosis group. The baPWV, age, systolic blood pressure, mean arterial pressure and diastolic blood pressure were significantly lower in the control group than those in the vascular sclerosis group (all P<0.05). Logistic regression analysis showed that high-density lipoprotein cholesterol, alanine aminotransferase and amylase were protective factors, and alkaline phosphatase and creatinine were risk factors of arterial stiffening (all P<0.05). The combined nomogram model scores including age, mean arterial pressure and the above five laboratory indicators indicated that mean arterial pressure and serum creatinine levels were strongly correlated with vascular sclerosis. The ROC curve suggested that the nomogram model had good prediction ability. Conclusions: Age, mean arterial pressure, high-density lipoprotein cholesterol, alanine aminotransferase, alkaline phosphatase, amylase and creatinine are independently determinants for increased vascular stiffness. The combined prediction model in this study can provide reference for individualized clinical risk prediction of vascular sclerosis in the octogenarian elderly.

Impact of a mild scrotal heating on sperm chromosomal abnormality, acrosin activity and seminal alpha-glucosidase in human fertile males.

The aim of this study was to observe sperm aneuploidy, DNA integrity, seminal alpha-glucosidase (NAG) and acrosin activity (AA) under testicular heat stress (SH). Spermatozoa were obtained from 30 healthy adult volunteers subjected to scrotal warming at 43°C for 30-40 min on two successive days per week for 3 months between February 2012 and September 2016. Aniline blue (AB), acridine orange (AO) staining, TUNEL assay and FISH analysis to evaluate sperm function, sperm DNA integrity and chromosomal abnormalities were carried on before, during and after SH. Sperm AA and NAG was measured by microplate reader. The mean parameters of sperm parameters, AA and NAG were significantly decreased. In contrast, the mean percentage of sperm DNA fragmentation and the proportion of aneuploidy of chromosomes 13, 18, 21, X and Y were significantly increased for spermatozoa collected during SH versus before SH (p < .01-.001). After stopping scrotal heating for 3 months, most parameters were completely restored to pre-SH levels. Sperm parameters, sperm DNA integrity, chromosomes, AA and NAG are affected by scrotal exposure to constant SH temperatures several degrees over normal physiological temperature, and after treatment, these parameters were reversibly restored to the level before SH in adult men.

Proteomic and gene expression analyses during bolting-related leaf color change in Brassica rapa.

Bolting and flowering are key processes during the growth and development of Chinese cabbage (Brassica rapa L. ssp pekinensis). Understanding the molecular mechanisms underlying bolting and flowering is of significance for improving production of the vegetable. A leaf-color change from bright green to gray-green has been observed following differentiation of the flowering stem and before bolting in the vegetable, and is considered to be a signal for bolting. Proteomics in meristem tissues of an inbred line (C30) were analyzed by two-dimensional electrophoresis during the transition period. We found that some proteins were specifically expressed while others were differentially expressed. Among these, 17 proteins were specifically expressed before the color change, 18 were specifically expressed after the color change, 21 were downregulated during the color change, and 29 were upregulated. Mass spectrometric analysis (MALDI-TOF-TOF/MS) was used to analyze 17 protein spots, and four proteins (subunit E1 of vacuolar-type H+ transporter ATPase, the large subunit of Rubicon, S-adenosylmethionine synthetase, and tubulin α-2) were identified. qPCR analysis was conducted to quantify the expression of genes encoding these proteins during the transitional period. The expression of BrVHA-E1, BrSAMS, BrrbcL, and BrTUA6 was significantly different before and after the leaf-color change, suggesting that these genes might be involved in regulating flower differentiation and bolting.

Regulation of bolting and identification of the α-tubulin gene family in Brassica rapa L. ssp pekinensis.

Microtubules are important components of eukaryotic cells, and they play vital roles in cell morphogenesis, carrying of signaling molecules, transport of materials, and establishing the cell polarity. During bolting of biennial plants, cell division and elongation are involved, and cell elongation inevitably involves the microtubules arrangement and expression of related genes. So we deduce that it is of great significance to figure out the mechanism of bolting and flowering in which TUA genes are involved. In the present study, bioinformatic methods were used to predict and identify the α-tubulin gene family (BrTUAs) in Brassica rapa L. ssp pekinensis (Chinese cabbage) through the alignment of AtTUA gene sequence from Arabidopsis thaliana with the B. rapa genome database (http://brassicadb.org/brad/) using the basic local alignment search tool. The change in the structure and functions of BrTUAs during the process of evolution, cis-acting elements in the promoter sequences of BrTUAs, and the expression of the identified genes was also analyzed. Twelve members of the α-tubulin gene family were identified from Chinese cabbage. The gene length, intron, exon, and promoter regions were determined to have changed significantly during the genome evolution. Only five of the 12 members were encoded completely and were observed to differ in their spatial and temporal expression. The five BrTUA promoter sequences contained different numbers of cis-elements responsive to light and low-temperature response, cis-elements responsive among which hormonal responses were significantly different. We also report that the BrTUAs were involved in the regulation of the bolting in Chinese cabbage, and propose that this process could be controlled by regulating the expression of BrTUAs.

Genetic analysis of floral organ size in broccoli × cabbage via a mixed inheritance model of a major gene plus polygene.

Broccoli and cabbage are important vegetable crops that produce hybrid seeds after insect pollination; the size of floral organs is crucial for this process. To investigate the genetic characteristics of floral organ sizes (corolla width, petal length and width, and lengths of stamen, anther, style, and stigma) and to improve the flower size and breeding efficiency of broccoli, we used multi-generation analysis of a major gene plus polygene model. Six populations obtained from a broccoli inbred line 93219 (small floral organs) and cabbage inbred line 195 (large floral organs) were used for the analysis. Corolla and petal width and stamen and anther length were controlled by the additive-dominance-epistasis polygene model. The heritability of these traits in BC1, BC2, and F2 generations was high (72.80-93.76%). Petal and stigma length were governed by the two major genes of additive-dominance-epistasis effects plus additive-dominance polygene model; the major gene heritability in the F2 generation were 79.17 and 65.77%, respectively. Style length was controlled by one major gene of additive-dominance effects plus additive-dominance-epistasis polygene model; the major gene heritability in BC1, BC2, and F2 were 40.60, 10.35, and 38.44%, respectively; the polygene heritability varied from 41.85 to 68.44%. Our results provide important genetic information for breeding, which could guide improvement of flower-related traits and lay the foundation for quantitative trait loci mapping of the flower-size traits in Brassica.

[Effect of GTPase activating protein Git2 on metastasis in breast cancer].

OBJECTIVE: To investigate the effect of GTPase activating protein Git2 on metastasis in breast cancer. METHODS: Git2 gene over-expression was induced by Git2 cDNA, and Git2 gene knockdown was induced by Git2 ShRNA lentivirus in four breast cancer cell lines. Six-week old wide type female mice were also used in this study. The cells were tagged with luciferase and injected into wide type female mice by tail vein or 4(th) mammary fat pad, respectively, to establish a cancer metastasis model. In vivo real time imaging system and immunohistochemical staining were used to detect the cancer metastasis. RESULTS: The relative mRNA expression level of Git2 (normalized by GAPDH) in the 4T1, 4TO7, 168FARN and 67NR cells were 0.91±0.03, 0.125±0.06, 0.131±0.04 and 0.92±0.04, respectively. The expression of EMT marker E-cadherin was inhibited and N-cadherin and vimentin were enhanced when Git2 was over-expressed in 168FARN cells and 4TO7 cells expressing low level of Git2, whereas the expression of E-cadherin was increased and N-cadherin and vimentin were decreased when Git2 was knocked down in 67NR cells and 4T1 cells expressing high level of Git2. Furthermore, over-expression of Git2 promoted 4TO7 cells to progress from micro-metastasis to macro-metastasis. The down-regulation of Git2 pushed 67NR cells to intravasate into blood circulation and suppressed the metastatic ability of 4T1 cells. The number of bioluminescence photos of lung metastatic 4T1-Luc-KD cells was (0.4±0.05)×10(6,) compared with (3.0±0.04)×10(6) in the control 4T1-Luc cells, showing a significant difference (P<0.05). CONCLUSION: Our results indicate that Git2 is involved in breast cancer initiation and metastatic colonization.

Identification of sequence-related amplified polymorphism and insertion-deletion markers linked to the male fertility restorer gene of pol-like CMS06J45 in heading Chinese cabbage (Brassica rapa subsp pekinensis).

In order to map the restorer gene BrRfp of the polima (pol)-like cytoplasmic male sterility (CMS) 06J45 line in heading Chinese cabbage, an F2 segregating population with 258 individuals of CMS06J45 and the restorer line 01S325 were tested by sequence-related amplified polymorphism (SRAP) and insertion-deletion (InDel) technologies combined with the bulked segregant analysis method. As a result, two SRAP markers, me3em3.366 and pm88bg5.263, that were linked with the BrRfp gene were identified from 463 SRAP primer pairs. By cloning, sequencing, and basic local alignment search tool analysis, the two markers were targeted to the BGIScaffold000053 of Brassica rapa in the Brassica database. Using the BGIScaffold000053 sequence, four InDel primer pairs were designed and identified to be linked with the BrRfp gene in this population. Linkage analysis showed that these markers were distributed on both sides of the BrRfp gene, the linkage distances of two nearest markers InDel878.1125 and InDel920.713 were 0.82 and 0.46 cM, respectively, and the BrRfp gene was restricted to a 243-kb genomic region of B. rapa. These specific markers provided basic information for map-based cloning of the BrRfp gene and will be very valuable for the marker-assisted selection of a new restorer line in heading Chinese cabbage.

Clinical efficacy of modified sacral fixation under Leonardo da Vinci robot laparoscopy for pelvic organ prolapse.

OBJECTIVE: The aim of this study was to analyze the clinical efficacy of modified sacral fixation under Leonardo da Vinci robot laparoscopy for pelvic organ prolapse (POP). PATIENTS AND METHODS: Sixty POP patients admitted to our hospital from January 2020 to December 2021 were picked and divided into Group A (laparoscopic Y-mesh, n = 20), Group B (laparoscopic sacrovaginal fixation, n = 20), and Group C (da Vinci robotic sacral fixation, n = 20). These three groups were compared in terms of the perioperative indexes, such as operation time, intraoperative blood loss, postoperative indwelling catheter days, anal exhaust time, postoperative hospitalization days, etc. The occurrence of short-term and long-term complications in the three groups was compared. The changes of the following index values in the POP quantification system (POP -Q) staging before and 1 year after surgery were recorded and compared among the three groups. It mainly includes the midline of the anterior vaginal wall at 3 cm from the hymenal margin (Aa), the farthest point of the anterior vaginal vault from point Aa (Ba), the farthest point of the ectocervix (C), the location of the posterior vaginal vault or rectal uterine trap (D), the midline of the posterior vaginal wall at 3 cm from the hymenal margin (Ap), and the reflection of the posterior vaginal vault at the farthest point from the Ap point (Bp) values. The changes in Pelvic Floor Distress Inventory-Short Form 20 (PFDI-20) and Pelvic Organ Prolapse/Urinary Incontinence Sexual Questionnaire (PISQ-12) were recorded and compared before and 1 year after the operation. RESULTS: The patients in Group C had significantly lower intraoperative bleeding, postoperative indwelling catheter days, anal exhaust time, and postoperative hospitalization days compared with those in Group A and Group B (p < 0.05). There existed no statistical difference in the incidence of short-term and long-term complications between Group B and Group C (p > 0.05), but both were much lower than Group A (p < 0.05). The differences in POP-Q staging, PFDI-20 scale, and PISQ-12 scale were not statistically significant among the three groups before surgery (p > 0.05), and the POP-Q staging Aa, Ba, C, D, Ap, and Bp values, PFDI-20 scale, and PISQ-12 scale were strongly improved in three groups after the surgery (p < 0.05). However, the POP-Q staging, PFDI-20 scale, and PISQ-12 scale among the three groups had no obvious difference after the surgery (p > 0.05). CONCLUSIONS: The efficacy of modified sacral fixation under Leonardo da Vinci robot laparoscopy for POP was comparable to that of laparoscopic Y-mesh treatment and laparoscopic sacral vaginal fixation. However, da Vinci's robotic sacral fixation had the advantages of less intraoperative bleeding and faster postoperative recovery, which helped patients recover quickly and improved their quality of life.

Polymorphisms in human histamine receptor H4 gene are associated with atopic dermatitis.

BACKGROUND: Atopic dermatitis (AD) is a chronic skin disease affecting more than 15% of children and 2% of adults. A strong connection between genetic factors and AD has been described for a long time. Histamine receptor H4 (HRH4) has been shown to be related to different kinds of allergic and autoimmune disorders. However, an association between HRH4 and AD has not yet been reported. OBJECTIVES: To examine a possible association between HRH4 and AD. METHODS: Genomic DNA from 301 patients with AD and 313 healthy controls was extracted and three exons of HRH4 were sequenced. RESULTS: We found three new single nucleotide polymorphisms (SNPs) in HRH4 which were significantly associated with AD: ss142022671 [odds ratio (OR) 1.87, 95% confidence interval (CI) 1.24-2.81; P = 0.002], ss142022677 (OR 4.40, 95% CI 2.42-8.00; P = 1.5 x 10(-7)) and ss142022679 (OR 4.26, 95% CI 2.38-7.61; P = 1.3 x 10(-7)). The SNPs ss142022677 and ss142022679 were found to be in strong linkage disequilibrium (D' = 0.98; r(2) = 0.92). Two-SNP haplotype analysis (ss142022677 and ss142022679) showed that the major AA haplotype was protective against AD (OR 0.22, 95% CI 0.12-0.40; P = 3.1 x 10(-8)) and the minor TT haplotype was significantly associated with AD (OR 4.13, 95% CI 2.27-7.54; P = 6.6 x 10(-7)). In addition, in a three-SNP haplotype analysis (ss142022671, ss142022677 and ss142022679), the major TAA haplotype was protective against AD (OR 0.46, 95% CI 0.31-0.69; P = 0.0001), while the complementary ATT haplotype was found to be significantly associated with AD (OR 3.81, 95% CI 2.03-7.14; P = 8.3 x 10(-6)). CONCLUSIONS: Polymorphisms of ss142022671, ss142022677 and ss142022679 in HRH4 are associated with AD.

Molecular and functional analysis of the poly-ß-hydroxybutyrate biosynthesis operon of Pseudomonas sp BJ-1.

The operon comprising the genes for poly-ß-hydroxybutyrate (PHB) biosynthesis in Pseudomonas sp BJ-1 was cloned and sequenced. Sequence analysis of 8991 bp revealed that the regions contain two related operons. The first operon contains the three genes phbA, phbB and phbC, and the other contains the two genes flp1 and flp2. The deduced amino acid sequences of PHBA and PHBB showed high identity with other bacterial PHB genes. Transcription of the three genes of the first operon is controlled by a single hypothetical promoter region, whereas the other two flp genes are controlled by two hypothetical promoter regions. Analysis of expressed protein at different times showed that PHBA protein levels increased from 0 to 4 h; PHBB and PHBC showed similar kinetics. Detection of enzyme activity showed three proteins with bioactivity and biological function in the synthesis of PHB intermediates.

Surface plasmon-enhanced micro-cylinder mode in photonic quasi-crystal.

Two-dimensional micro-cylinder patterns of dodecagonal photonic quasi-crystal (12-PQC) and tetragonal photonic crystal (2-PC) were fabricated on the top surface of a GaN light-emitting diode (LED). The patterns were evaporated with a 10-nm-thick Ag film. Spatially resolved surface emission was recorded and analysed by scanning near-field optical microscopy. Electromagnetic energy was confined and enhanced at the top surface when the surface plasmon (SP) resonated. The enhancement factor for 12-PQC was 1.9 times that of 2-PC, 8.6 times that of non-patterned LED in the near field and 6.7 times in the far field, respectively. Finite-difference time-domain simulations are consistent with the experimental data. The results show that with a patterned structure on the top surface of an LED, the light emission can be greatly enhanced due to SP resonance.

Suppression of vascular endothelial growth factor (VEGF) expression by targeting the Bcr-Abl oncogene and protein tyrosine kinase activity in Bcr-Abl-positive leukaemia cells.

Studies have shown that vascular endothelial growth factor (VEGF), a major and potent inducer of angiogenesis, is directly triggered by the disease-related oncogene Bcr-Abl in Bcr-Abl-positive cells. In this study, inhibition of Bcr-Abl tyrosine kinase activity by imatinib significantly decreased VEGF expression in Bcr-Abl-positive K562 cells in vitro. Imatinib treatment in vivo of nude mice xenografted with K562 cells resulted in a significant reduction in tumour size and microvessel density compared with untreated tumours. In addition, interfering with Bcr-Abl oncogene expression with small interfering RNAs (siRNAs) not only induced a specific reduction of Bcr-Abl mRNA and protein expression, but also efficiently inhibited the expression of VEGF in K562 cells. Combined treatment with imatinib and Bcr-Abl-targeting siRNAs resulted in an enhanced effect on VEGF suppression in K562 cells. The combined application of Bcr-Abl-targeting siRNAs and imatinib may provide a potent novel therapeutic approach for chronic myeloid leukaemia.

Probiotic administration of lactobacillus rhamnosus GR-1 attenuates atherosclerotic plaque formation in ApoE-/- mice fed with a high-fat diet.

OBJECTIVE: To investigate the effect of Lactobacillus rhamnosus GR-1 on atherosclerotic progression in apolipoprotein-E knockout (ApoE-/-) mice fed with a high-fat diet and the underlying mechanisms of its action. MATERIALS AND METHODS: Eight-week-old ApoE-/- mice were treated with Lactobacillus rhamnosus GR-1 daily for 12 weeks. ApoE-/- mice in the vehicle group and wild type (WT) mice were treated with normal saline. Serum lipid levels, histopathological analysis of the aorta, oxidative and inflammatory indexes and activation of the nuclear factor-kappa B (NF-κB) signaling pathway were examined. RESULTS: Compared to ApoE-/- mice in the vehicle group, no changes in body weight or serum lipid levels were found in ApoE-/- mice treated with Lactobacillus rhamnosus GR-1. However, the administration of GR-1 slowed down the development of atherosclerosis and reduced plaque formation. Additionally, GR-1 attenuated the development of oxidative stress and chronic inflammation in a dose-dependent manner in ApoE-/- mice fed a high-fat diet. Furthermore, in ApoE-/- mice treated with GR-1, GR-1 was demonstrated to have a role in inhibiting the translocation of NF-κB p65 from the cytoplasm to the nucleus and suppressing the degradation of IκB-α. CONCLUSIONS: We showed that the administration of GR-1 decreased atherosclerotic lesion size in ApoE-/- mice by reducing oxidative stress and inflammation. Additionally, the NF-κB signaling pathway might mediate these effects.

A rare oesophageal inflammatory myofibroblastic tumour treated by endoscopy.

An inflammatory myofibroblastic tumour is a mesenchymal neoplasm that mostly involves the lung and rarely involves the oesophagus. Surgery has been most commonly used for the treatment of oesophageal inflammatory myofibroblastic tumours but there are no definite guidelines for their diagnosis and treatment. We describe the case of a 60-year-old woman presenting with dysphagia and poor appetite who was diagnosed with a submucosal oesophageal tumour by contrast enhanced computed tomography and ultrasonography endoscopy. She was treated successfully by endoscopic submucosal dissection with no complications. The final diagnosis was confirmed by pathological examination.

Study on the mechanism of AMPK signaling pathway and its effect on apoptosis of human hepatocellular carcinoma SMMC-7721 cells by curcumin.

OBJECTIVE: Liver cancer is a common malignant tumor in the digestive system. Curcumin is a kind of phenolic pigment, which is extracted from herbage and has a plenty of physiological roles in anti-inflammation, anti-oxidation and anti-tumor. In our study, human hepatoma SMMC-7721 cell lines were selected and treated with curcumin to detect its effects on the apoptosis and AMPK signaling pathway. MATERIALS AND METHODS: Human liver cancer cell strain SMMC-7721 was cultured and treated with different curcumin concentrations for different times followed by measuring the changes of cell proliferation activity and cycle by MTT and flow cytometry, respectively. Protein expression of Bcl-2, Bax and Caspase-3 were tested by Western blot, and the activation level of AMPK was also detected. RESULTS: Different concentrations of curcumin could inhibit the proliferation of tumor cells in a dose-dependent manner. After 48 h inhibition by curcumin with a concentration of 40 mmol/L, the inhibitory effect was more obvious with statistically significant (p<0.05). The number of human liver cancer SMMC-7721 cells increased in G1 stage and decreased in S stage after treated with different concentrations of curcumin. During the G1 stage to the S stage, inhibition occurred and the effect of curcumin intervention group with 40 mmol/L was more evident than that of 10 mmol/L group, 20 mmol/L group and the control group with statistically significant (p<0.05). SMMC-7721 cell stains had been intervening by curcumin with concentrations of 10 mmol/L, 20 mmol/L and 40 mmol/L for 12 h, 24 h and 48 h, as the drug concentration increased, the reaction time prolonged, the protein expressions of Bcl-2 and Survivin were significantly decreased and Bax protein expression was significantly increased (p<0.05). CONCLUSIONS: Curcumin decreased the proliferation activity of tumor cells, increased the cell quantities in G1 stage and decreased the cell numbers in S stage in human liver cancer SMMC-7721 cells. The Bcl-2 and Survivin proteins were downregulated and Bax protein was upregulated; furthermore, the AMPK signaling pathway was activated.

Comparison of responses to acetylcholine and serotonin on isolated canine and human coronary arteries.

Canine and human coronary arteries were studied in organ baths to compare the responses to acetylcholine and serotonin in the two species. The human coronary rings were isolated from seven patients without cardiac disease (mean age 15 years, range 7-20). In one set of experiments canine and human preparations were incubated with phentolamine, propranolol and ketanserin (all at 1 mumol.litre-1 concentration) and precontracted with prostaglandin F2 alpha (PGF2 alpha 1-2 mumol.litre-1). Acetylcholine (0.1-10 mumol.litre-1) and serotonin (0.1-100 mumol.litre-1) relaxed canine preparations dose dependently, the maximum responses (expressed as % of depression of PGF2 alpha response) being 84 (SEM 6)% (n = 9) and 51(5)% (n = 6) respectively. In the same experimental conditions, acetylcholine and serotonin failed to relax the human coronary rings (n = 11) while substance P and bradykinin induced relaxations of 72(4)% (n = 11) and 66(7)% (n = 11) of PGF2 alpha response respectively. In another set of experiments, dose-contraction curves were constructed for acetylcholine or serotonin (in presence of phentolamine and propranolol). On human rings with endothelium, methylene blue (10 mumol.litre-1), a non-specific inhibitor of endothelium derived relaxing factor (EDRF), potentiated these dose-contraction curves: markedly for serotonin, the EC50 decreasing from 1.2(0.2) to 0.22(0.08) mumol.litre-1 (n = 11, p less than 0.01) with a significant increase in the maximal response); and slightly for acetylcholine, EC50 decreasing from 0.84(0.11) to 0.40(0.13) mumol.litre-1 (n = 10, p less than 0.05) without significant change in the maximal response.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevention by selenium supplementation of cyclosporin-A-induced vascular toxicity.

OBJECTIVE: The aim was to determine whether selenium supplementation, an important component of glutathione peroxidase, might attenuate cyclosporin (Cx)-induced vascular toxicity. METHODS: Four groups of rats were treated in parallel: the first group was supplemented with selenium (sodium selenite, 0.5 mg.kg-1) orally (p.o.) for 5 weeks and the same dose of selenium plus Cx 20 mg.kg-1 (i.m.) during the 6th week; group 2 received Cx only (20 mg.kg-1 i.m. for 1 week); group 3 was supplemented with selenium (0.5 mg.kg-1 p.o., for 6 weeks) and group 4 served as control. Thoracic aortas isolated from these various groups were studied in organ baths. RESULTS: In comparison with the control group, selenium supplementation did not modify acetylcholine (Ach)- and nitroprusside-induced relaxations. In group 2, endothelium-dependent relaxations (Ach) were markedly impaired and endothelium-independent relaxations (nitroprusside) were shifted to the right; with selenium supplementation (group 1), the responses to Ach were partially restored whereas the rightward shift of the concentration-response curves to nitroprusside persisted. Incubation with superoxide dismutase (SOD, 150 IU.ml-1) or selenium (1 microgram.ml-1) (but not with selenium plus an inhibitor of the glutathione redox cycle) improved the relaxations to Ach in group 2. CONCLUSIONS: The vascular toxicity of Cx seems related to generation of oxygen-derived radicals promoting EDRF destruction and is attenuated by selenium supplementation.