Effects of Zentangle art workplace health promotion activities on rural healthcare workers.

OBJECTIVES: Workplace health promotion activities have a positive effect on emotions. Zentangle art relaxes the body and mind through the process of concentrating while painting, achieving a healing effect. This study aimed to promote the physical and mental health of rural healthcare workers through Zentangle art-based intervention. STUDY DESIGN: This was a quasi-experimental pilot study. METHODS: A Zentangle art workshop was held from November 2019 to July 2020. A total of 40 healthcare workers were recruited. The participants were asked to provide baseline data, and the Brief Symptom Rating Scale (BSRS-5), work stress management effectiveness self-rating scale, General Self-Efficacy Scale (GSES), and Workplace Spirituality Scale (WSS) were administered before and after the workshop. SPSS 22.0 statistical package software was used to conduct the data analysis. RESULTS: The median age (interquartile range [IQR]) was 32.00 years (23.00-41.75 years). The Wilcoxon signed-rank test revealed that the median (IQR) BSRS-5 postintervention score was 4.0 (1.25-5.0), which was lower than the preintervention score (P = 0.004). The postintervention score for the work stress management effectiveness self-rating scale was 36.5 (31.0-40.0), which was also lower than the preintervention score (P = 0.009). A higher score for the GSES or WSS indicated improvements in stress management and self-efficacy. The GSES postintervention score 25.00 (21.0-30.75) was significantly higher than the preintervention score (P = 0.010), and the WSS postintervention score 104.0 (88.0-111.75) was significantly higher than the preintervention score (P = 0.005). CONCLUSIONS: The study provides evidence that painting therapy can effectively relieve stress, reduce workplace stress and frustration, enhance self-efficacy, and increase commitment to work among healthcare workers, thus improving their physical, mental, and spiritual well-being. Zentangle art provides employees with multiple channels for expressing their emotions and can improve the physical and mental health of healthcare workers in the workplace. It is beneficial and cost-effective and can serve as a benchmark for peer learning.

Exome sequencing in 32 patients with anophthalmia/microphthalmia and developmental eye defects.

Anophthalmia/microphthalmia (A/M) is a genetically heterogeneous birth defect for which the etiology is unknown in more than 50% of patients. We used exome sequencing with the ACE Exome(TM) (Personalis, Inc; 18 cases) and UCSF Genomics Core (21 cases) to sequence 28 patients with A/M and four patients with varied developmental eye defects. In the 28 patients with A/M, we identified de novo mutations in three patients (OTX2, p.(Gln91His), RARB, p.Arg387Cys and GDF6, p.Ala249Glu) and inherited mutations in STRA6 in two patients. In patients with developmental eye defects, a female with cataracts and cardiomyopathy had a de novo COL4A1 mutation, p.(Gly773Arg), expanding the phenotype associated with COL4A1 to include cardiomyopathy. A male with a chorioretinal defect, microcephaly, seizures and sensorineural deafness had two PNPT1 mutations, p.(Ala507Ser) and c.401-1G>A, and we describe eye defects associated with this gene for the first time. Exome sequencing was efficient for identifying mutations in pathogenic genes for which there is no clinical testing available and for identifying cases that expand phenotypic spectra, such as the PNPT1 and COL4A1-associated disorders described here.

Central nervous system (CNS) relapse in diffuse large B cell lymphoma (DLBCL): pre- and post-rituximab.

Central nervous system (CNS)-directed prophylactic intrathecal (IT) therapy is indicated in patients with Burkitt and acute lymphoblastic lymphoma. Its role in diffuse large B cell lymphoma (DLBCL), a heterogeneous subtype, is less well defined. While addition of rituximab to standard cyclophosphamide-hydroxydaunorubicin-oncovin-prednisone (CHOP) chemotherapy (R-CHOP) has improved the outcomes of DLBCL patients, its role in reducing CNS relapse is unclear. We aim to (1) evaluate the clinical risk factors predictive of CNS relapse, (2) the role of rituximab in influencing CNS relapse, and (3) role of intrathecal prophylaxis. Four hundred ninety-nine patients with DLBCL from 2000 to 2008 were included (CHOP 179 vs. R-CHOP 320). IT prophylaxis was administered to 82 patients based on our institution's guidelines. Baseline characteristics between CHOP- and R-CHOP-treated patients were similar. Although R-CHOP significantly increased the complete remission rate from 71% to 81% (P < 0.01), CNS relapse rates remained unchanged (R-CHOP 6% vs. CHOP 5.1%). On multivariate analysis, poor performance status (Eastern Cooperative Oncology Group >1; hazard ratio (HR) = 2.01, 95% confidence interval (CI) 1.29-3.14), failure to attain remission (non-complete response (CR) vs. CR: HR = 2.39, 95% CI = 1.03 to 5.51), testicular (HR = 6.67, 95% CI = 1.62 to 27.53), kidney (HR = 20.14, 95% CI = 5.23 to 77.46), and breast involvement (HR = 6.14, 95% CI = 1.61 to 23.37) were each independently predictive of CNS relapse. Use of IT prophylaxis did not appear to decrease CNS relapse. Median survival after CNS relapse was 3.2 months. CNS relapse, a fatal event, remains a challenge in R-CHOP-treated patients. IT prophylaxis may not be sufficient to reduce CNS relapse, and strategies including systemic agents with high CNS penetration should be evaluated in high-risk patients identified in this study.

The short-to-midterm results of endovascular stent grafting for acute thoracic aortic diseases in Chinese patients.

OBJECTIVE: To review the results of endovascular treatment of acute thoracic aortic diseases in a group of Chinese patients. DESIGN: Retrospective study. SETTING: A tertiary referral hospital with a cardiothoracic surgery service. PATIENTS: All 15 patients presenting with acute thoracic aortic diseases between September 2001 and October 2005 inclusive, of whom eight had traumatic rupture, four had complicated acute dissections, two had mycotic aneurysms, and one an aneurysm with an aortobronchial fistula. INTERVENTIONS: Thoracic aortic stent grafting. MAIN OUTCOME MEASURES: Immediate success, 6-month and 1-year survival rates. RESULTS: The median follow-up period was 20.6 months (range, 0-50.1 months). Stent grafts were deployed with immediate success in all patients. Two patients had ancillary bypass surgery for the supra-aortic branches. There were two in-hospital deaths. Four sustained access artery injury and needed graft repair. Computed tomography at 1 month showed complete thrombosis of the aneurysmal lumen or the thoracic aortic false lumen in 12 of 13 survivors. Computed tomography at 6 months showed complete thrombosis of the aneurysmal lumen or the false lumen in nine of 10 patients due for follow-up. Both 6-month and 1-year survival rates were 87%. CONCLUSIONS: Thoracic aortic stent grafting for acute thoracic aortic disease is feasible and has a high success rate, with good short-to-midterm results. However, the large size of the stent graft introducer set imposes a high risk of access artery injury, for which further improvements are necessary.

Minimally invasive parathyroidectomy by unilateral neck dissection--experience in a regional hospital in Hong Kong.

OBJECTIVE: To compare the efficacy and safety of minimally invasive open parathyroidectomy with localised unilateral neck dissection to the conventional method of bilateral neck exploration and parathyroidectomy as a surgical treatment for primary hyperparathyroidism. PATIENTS AND METHODS: Eleven patients diagnosed with primary hyperparathyroidism at Queen Elizabeth Hospital from 1 January 2002 to 31 December 2002 were treated surgically with minimally invasive open parathyroidectomy. Their results were compared to a retrospective series of 15 patients treated by conventional bilateral neck exploration and parathyroidectomy between 1 January 2001 and 31 December 2001. Demographic data; cure, recurrence, and complication rates; operating time; and hospital stay were analysed. RESULTS: The cure rate was 100% in both groups. There was no recurrence in either group. Minor complication rates were 9% and 20% in the minimally invasive open parathyroidectomy and the control groups, respectively. Mean operating time was 63 minutes in the minimally invasive open parathyroidectomy group, and 92 minutes in the control group. The mean postoperative hospital stay for the minimally invasive open parathyroidectomy group was 1.36 days. Three of these procedures were performed as day surgery. The mean hospital stay for the control group was 2.93 days. The operating time and hospital stay were significantly shorter in the minimally invasive open parathyroidectomy group. CONCLUSION: Minimally invasive open parathyroidectomy is a viable alternative treatment method for primary hyperparathyroidism. It has comparable cure and recurrence rates to the conventional approach. It is safe, with a lower complication rate, and has the benefits of being a shorter procedure and allowing a shorter hospital stay. It can be performed as day surgery, further reducing hospital costs.

Sorption of Cr(VI) and Cu(II) in aqueous solution by ethylenediamine modified rice hull.

The sorption characteristics of Cr(VI) and Cu(II) by ethylenediamine modified rice hull from single and binary metal ion solutions were evaluated under various experimental conditions. Optimal Cr(VI) and Cu(II) removal from single metal ion solutions occurred at pH 2.0 and 5.5, respectively. Simultaneous removal of Cr(VI) and Cu(II) occurred at pH greater than 3.0. The sorption kinetics of Cr(VI) and Cu(II) from single and binary metal ion solutions were studied with reference to metal concentration, agitation rate and particle size. Sorption of Cr(VI) was more rapid than Cu(II). The kinetics of metal ion sorption fitted a pseudo-second order expression. The variation in the initial uptake rates was very small at an agitation rate beyond 150 rpm and sorption was generally independent of particle size. Equilibrium sorption data could be fitted into the Langmuir isotherm equation. Maximum sorption capacities of ethylenediamine modified rice hull for Cr(VI) at pH 2 and Cu(II) at pH 4 in single metal solutions were 0.45 and 0.06 mmol g(-1), respectively. This corresponds to an enhancement factor of 2.6 and 3 fold for Cr(VI) and Cu(II), respectively, compared to natural rice hull. A synergistic effect was observed for sorption of these ions in binary metal solutions.

Melatonin protects against cardiac toxicity of doxorubicin in rat.

Doxorubicin (DOX) is commonly used for the treatment of hematological and solid tumors. However, there are serious toxic effects on the cardiovascular system, which limits the application of the drug. Recently, melatonin has been reported to have immunomodulatory effect in addition to lowering cholesterol levels as well as inhibiting malignant tumors. In this study, the effect of melatonin against the toxicity of doxorubicin was investigated in rats. Hemodynamic function, pathological and biochemical changes were determined in different treated hearts. Our findings showed that a significant protection by melatonin (6 mg kg(-1) for 15 days, cumulative dose of 90 mg kg(-1)) against the DOX-induced toxicity was observed. Cardiac function was improved and lipid peroxidation decreased after melatonin treatment. It is concluded that melatonin provides protection against doxorubicin toxicity via an attenuation of lipid peroxidation.

Effect of light on 5-methoxyindole-3-acetic acid in the rat.

This study aims to determine the effects of light on the levels of 5-MIAA to provide further information on this indoleamine, using a sensitive and specific radioimmunoassay (RIA) for immunoreactive 5-methoxyindole-3-acetic acid (5-MIAA) developed in our laboratories using a specific antibody and tritiated label. Significant differences were found in the immunoreactive 5-MIAA levels between mid-light and mid-dark pineal glands in rats adapted to 12/12 hrs light/dark and in constant darkness. Under constant light, the circadian rhythm was abolished. The rat serum displayed no diurnal variations in 5-MIAA levels under aux photic conditions. The persistence of rhythms found in constant darkness but abolished in constant light suggests that the pineal 5-MIAA is endogenous and uses light as an environmental cue. In addition to melatonin, 5-MIAA could possibly be another pineal photoperiodic signal in animals.

The growth arrest specific gene (gas6) protein is expressed in abnormal embryos sired by male golden hamsters with accessory sex glands removed.

Expression of growth arrest specific gene (gas6) and its receptors in embryonic and uterine tissues in normal pregnancy and pregnancy that produces abnormal embryos sired by hamsters with partial or total deletion of male accessory sex glands was studied by in situ hybridization, immunohistochemistry, reverse-transcription polymerization reaction and enzyme-linked immunoabsorbant assay. At oestrus, very strong gas6 mRNA and Gas6 expression were seen only in the uterine epithelium and endometrial glands. Upon implantation, both of them could be demonstrated in the decidualizing stroma. From day 4 to day 7 p.c, gas6 mRNA was present in the embryo, but Gas6 immunoreactivity was only found in those showing features of degeneration. The gas6:beta-actin mRNA ratio was low in oestrus and at day 4 of pregnancy but rose as the embryo grew. As for the receptors, Rse was detected in embryonic cells during days 5-7 p.c., and decidual cell from days 4 to 7 p.c., but Mer could be found in decidual cells and trophoblasts. It was concluded that gas6 had a role in endometrial transformation during decidualization and trophoblastic invasion. In the embryo, gas6 was transcribed, but the protein was only produced in response to need, such as when normal progression of development was threatened.

Ablation of paternal accessory sex glands is detrimental to embryo development during implantation.

The accessory sex glands are present in most mammals, but their function(s) have not yet been clearly defined. In the golden hamster, removal of all the glands or the ventral prostate alone have been shown to considerably reduce fertility, while the effect is milder if the ampullary glands only are removed. In this study, embryo development from the 5th to the 7th day after mating are examined. Structural and morphometric criteria such as cell number, cell density, embryo volume, volume fraction of proamniotic cavity further revealed that abnormalities can be demonstrated as early as day 5 in the embryos sired by males with the ventral prostate gland alone or all glands ablated. Twin implantation and deviation from normal implanted axis are also observed. This is likely to be attributed to attenuated cell proliferation, as indicated by proliferating cell antigen labelling and more necrotic cell death. Taken together, exposure of sperm to secretions of the male accessory sex glands in particular, the ventral prostate, is important for differentiation and multiplication of cells after the embryo has implanted.

Effects by doxorubicin on the myocardium are mediated by oxygen free radicals.

We hypothesized that doxorubicin (DOX) induces cardiotoxicity of myocardium via oxygen radicals. The present study is aimed at examining the membrane alterations by oxygen radicals generated by DOX in adult rats and cultured neonatal myocytes. Our results showed that DOX 1) decreased beta-adrenoceptor (BAR) density in the cell membrane, 2) increased the membrane permeability of cultured neonatal rat myocytes and 3) altered the ultrastructure of myofibrils and subplasmalemmal actin networks. These effects were reproducible by exogenous hydrogen peroxide. The antioxidant melatonin (MLT) inhibited enzyme leakage and peroxidation in a concentration-dependent manner. It is concluded that DOX induces cardiotoxicity through lipid peroxidation and melatonin is an effective antioxidant against the reactive oxygen intermediates generated by DOX.

Transferrin receptors on the plasma membrane of cultured rat astrocytes.

It is generally accepted that transferrin receptor is located in the endothelial cells of the brain, but its existence in other brain cell types is less established. In this study, a [(125)I]transferrin binding assay was used to determine whether there is transferrin receptor on the membrane of cultured rat cortical astrocytes (type 1) in vitro. The results demonstrated that cortical astrocytes (type 1) in suspension attracted [(125)I]transferrin with a saturable and specific binding. Scatchard and Hill plot analysis showed that the dissociation constant (K(D)) of the binding was about 3.5x10(-8) M and the number of receptors was about 7.1x10(4)/cell. The Hill coefficient was 0.99, approaching 1, indicating the absence of cooperativity. The receptor was specific both for rat and human transferrin. The binding of rat [(125)I]transferrin could be competitively and specifically inhibited by unlabeled iron-saturated rat and human transferrin, and no difference was found between interaction of rat or human transferrin with this receptor. The interaction of duck or camel transferrin with this receptor was found to be very weak. This study provides evidence for the presence of transferrin receptor on the plasma membrane of cultured rat brain astrocytes.

Increased expression of transferrin receptor on membrane of erythroblasts in strenuously exercised rats.

This study investigated the effects of strenuous exercise on transferrin (Tf)-receptor (TfR) expression and Tf-bound iron (Tf-Fe) uptake in erythroblasts of rat bone marrow. Female Sprague-Dawley rats were randomly assigned to either an exercise or sedentary group. Animals in the exercise group swam 2 h/day for 3 mo in a glass swimming basin. Both groups received the same amount of handling. At the end of 3 mo, the bone marrow erythroblasts were freshly isolated for Tf-binding assay and determination of Tf-Fe uptake in vitro. Tissue nonheme iron and hematological iron indexes were measured. The number of Tf-binding sites found in erythroblasts was approximately 674,500 +/- 132,766 and 1,270,011 +/- 235,321 molecules/cell in control and exercised rats, respectively (P < 0. 05). Total Fe and Tf uptake by the cells was also significantly increased in the exercised rats after 30 min of incubation. Rates of cellular Fe accumulation were 5.68 and 2.58 fmol. 10(6) cells(-1). min(-1) in the exercised and control rats, respectively (P < 0.05). Tf recycling time and TfR affinity were not different in exercised and control rats. Increased cellular Fe was mainly located in the stromal fraction, suggesting that most of accumulated Fe was transported to the mitochondria for heme synthesis. The findings demonstrated that the increased cellular Fe uptake in exercised rats was a consequence of the increased TfR expression rather than the changes in TfR affinity and Tf recycling time. The increase in TfR expression and cellular Fe accumulation, as well as the decreased serum Fe concentration and nonheme Fe in the liver and the spleen induced by exercise, probably represented the early signs of Fe deficiency.

Cerebellar granule cells acquire transferrin-free iron by a carrier-mediated process.

In this study, the mechanism of transferrin-free iron uptake by brain neuronal cells was investigated using the cultured cerebellar granule cells. Effects of incubation time, iron concentration, temperature and other divalent metals on the cellular uptake were determined. After five days of plating, the cells were incubated with different concentrations of transferrin-free iron in isotonic sucrose solution at different temperatures for a certain time. The cellular transferrin-free iron uptake was analysed by measuring the cellular radioactivity with a gamma-counter. The result showed that the cultured cerebellar granule cells had the capacity to acquire transferrin-free iron at pH 6.5, at which it was demonstrated that transferrin binds iron very poorly and only very little transferrin can be internalized by reticulocytes and HeLa cells. The iron uptake by cells increased with incubation time in a linear manner at a rate of 0.1076 pmol/microg protein/min within the first 10 min. The uptake was time- and temperature-dependent, iron concentration saturable, and inhibited by several divalent metal ions, such as Co2+, Zn2+, Mn2+ and Ni2+. These characteristics of transferrin-free iron uptake by the cultured cerebellar granule cells observed in this study, similar to those obtained from cells outside of the brain, implied that a carrier-mediated iron transport system might be present on the membrane of this type of brain neuronal cells. In addition, no significant difference in malondialdehyde measurement was found when the cells were incubated without or with the lower concentrations of iron (< 4 microM) for 20 min at 37 degrees C, demonstrating that this system was valid for studying membrane iron transport in this type of brain neuronal cell.

Expression of vascular endothelial growth factor (VEGF) and its receptors during embryonic implantation in the golden hamster (Mesocricetus auratus).

Expression of vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) and its receptors (flt-1 and flk-1) during the peri-implantation period (days 3, 4, 5, 6 and 7 post coitus) in the golden hamster was investigated by in situ hybridization, immunohistochemistry and the reverse transcription/polymerase chain reaction (RT-PCR). Three days after mating, in situ hybridization and immunohistochemical staining revealed weak VEGF expression only in the uterine epithelium; this expression was similar to that seen at oestrus. Flt-1 but no flk-1 immunoreactivity was observed. At day 4, the subepithelial stroma and embryo displayed immunoreactivity for VEGF and flt-1, whereas endothelial cells expressed both flt-1 and flk-1. At day 5, immunoreactivity for both VEGF and its receptors was detected in decidual cells and vascular endothelial cells. Only a few embryonic cells expressed VEGF mRNA but strong signals were noted in decidual cells. The patterns of VEGF and VEGF receptor expression were the same in the day-6 and day-7 embryos and decidua, except for an increase in intensity as development progressed. Based on these findings, we conclude that, in addition to its known actions on endometrial angiogenesis and tissue swelling, VEGF may also facilitate the proliferation and differentiation of the endometrium and help to sustain the avascular embryo during this early stage of development.

Transferrin-bound iron uptake by the cultured cerebellar granule cells.

Excessive brain iron has been found in several neurodegenerative diseases. However, little information is available about mechanism of iron uptake by different types of brain cells including neurons. In this study, transferrin-bound iron (Tf-Fe) accumulation in the cultured cerebellar granule cell was investigated in vitro. After 5 days of culture, the cells were incubated with 1 microM of double-labelled transferrin (1251-Tf-59Fe) at 37 degrees C for 60 min. The cellular Tf-Fe and transferrin (Tf) uptake was analysed. The result showed (1) Tf uptake by the cells increased rapidly at the first 5 min, reaching its maximum after about 20 min of incubation; (2) Tf-Fe uptake kept increasing in a linear manner during the whole period of incubation; (3) the addition of either NH4Cl or CH3NH2, the blockers of Tf-Fe uptake via inhibiting iron release from Tf within endosomes, decreased the cellular Tf-Fe uptake but had no significant effect on Tf uptake; (4) trypsin and unlabelled Tf-Fe inhibited the uptake rate of Tf-Fe as well as Tf. The results suggested that Tf-Fe transport across the membrane of this type of neuron, much like other mammalian cells, was mediated by Tf-TfR endocytosis. Dysfunction of Tf or TfR would possibly lead to iron irregulation in the brain and consequently cause damage to neuronal functions.

Plasma melatonin profile and hormonal interactions in the menstrual cycles of anovulatory infertile women treated with gonadotropins.

The patterns of plasma melatonin, gonadotropins, sex steroids and prolactin were studied in anovulatory infertile females undergoing ovulation induction with hMG/hCG. Melatonin levels were found to fluctuate during the menstrual cycle of these subjects with a nadir at mid-cycle and peak occurring at the early follicular/late luteal phases of the cycle (p < 0.05). Melatonin correlated negatively with estradiol during the follicular phase (r=-0.5180, p < 0.05) and positively with LH (5 + 0.6321, p < 0.05) in the luteal phase, respectively. Correlational analyses by partial and multiple correlations suggest that the effects of estradiol and LH on melatonin in the follicular phase are interdependent whereas the effect of LH on melatonin in the luteal phase is independent of the effects of other hormones. The results suggest that hormonal interactions and phases of the cycle are important variables contributing to the fluctuations in melatonin levels during the menstrual cycle.

Involvement of interleukin-2 in analgesia produced by Coriolus versicolor polysaccharide peptides.

AIM: To study the role of interleukin-2 (IL-2) and mediobasal hypothalamus (MBH) in analgesia produced by Coriolus versicolor polysaccharide peptide (PSP). METHODS: The IL-2 antiserum was injected i.c.v. or i.p. and the MBH was destroyed electrolytically. RESULTS: PSP i.g. 1 g.kg-1.d-1 for 6 d increased the pain threshold in tail stimulation-vocalization test in rats. This PSP-produced analgesia was blocked by i.c.v., but not i.p., IL-2 antiserum and disappeared after electrolytic lesion of MBH. CONCLUSION: The analgesia produced by PSP is mediated by IL-2 which is activated by PSP and interacts with IL-2 receptors in the MBH.

Differential inhibitory effects of melatonin analogs and three naphthalenic ligands on 2-[125I]iodomelatonin binding to chicken tissues.

We have compared the 50% inhibition values of 2-[125I]iodomelatonin ([125I]Mel) competition curves by melatonin and 3 naphthalenic ligands, N-[2-(7-methoxy-1-naphthyl) ethyl] cyclobutane carboxamide (S20642), N-propyl N-[2-(7-methoxy-1-naphtyl) ethyl] urea (S20753), and N-[2-(7-methoxy-1-naphthyl) ethyl] crotonamide (S20750), using membrane preparations of four tissues (lung, spleen, brain, and kidney) of the chicken simultaneously. In retired breeders, we have demonstrated that the affinities of S20642 were similar in the lung and spleen. However they were 2-fold lower in the brain and 80-fold lower in the kidney. Similar differential binding affinities to the melatonin receptors were observed in the four tissues of young male chicks. This suggests that age and sex have little influence on the differential inhibitory properties of melatonin and S20642 in the tissues studied. The addition of guanosine 5'-O-thiotriphosphate (GTPgammaS), which encouraged the uncoupling of melatonin receptor to the G protein complex, lowered the binding affinity of melatonin and S20642 in the tissues studied but their differential affinities in the four tissues were however maintained. The affinities of 5-methoxy-N-cyclopropanoyltryptamine (CPMT) in the kidney were also 5-10-fold lower than those in the lung, spleen, and brain of young male chicks. The distinctive differential affinities of melatonin, S20642, and CPMT for [125I]Mel binding sites in the chicken lung, spleen, brain, and kidney indicated that the binding sites in these tissues are heterogeneous. Our study implicated that the naphthalenic ligand S20642 may be a useful melatonin analog to distinguish melatonin receptor subtypes in tissues and a possible drug candidate worthwhile for further investigations.

Central ANG II receptor involved in carotid sinus reflex resetting in chronically stressed rats.

The performance of carotid sinus baroreceptor reflex (CSR) was characterized in chronically stressed rats by changing intracarotid sinus pressure (ISP) and constructing ISP-MAP (mean arterial pressure) relationship curve. The role of central angiotensin II (ANG II) receptors in the changes of CSR performance induced by chronic stress was determined. Rats were subjected to foot-shock stress for two weeks. The carotid sinus was isolated from the systemic circulation and the ISP changed in a stepwise manner. The results showed that in chronically stressed rats, ISP-MAP relationship curve shifted upward, the set point was significantly higher than that obtained from the unstressed group, and the reflex gain and the MAP range were significantly smaller than those in unstressed rats. After intracerebroventricular injection of saralasin (20 ng), MAP range was augmented and the set point decreased significantly. Injection of vehicle did not lead any significant differences between the parameters of the reflex measured before or after injection in either the stressed or the unstressed rats. Furthermore, administration of ANG II (10 microg) induced a significant increase in the set point and decrease in the reflex gain in the unstressed rats. The responses of CSR to ANG II were completely blocked by pretreatment of saralasin. These findings suggest that chronic stress could induce the decreased CSR function in the normotensives and central ANG II receptors involved in the resetting of CSR in the chronically stressed rats.