Pharmacokinetics of dexmedetomidine in Chinese post-surgical intensive care unit patients

BACKGROUND

Dexmedetomidine is a rather new drug in China. We sought to describe the pharmacokinetics of dexmedetomidine in patients requiring post-operative sedation and ventilation in our surgical intensive care unit.

METHODS

Twenty-two patients received post-operative infusions of dexmedetomidine at 6 μg/kg/h for 10 min, followed by 0.4 μg/kg/h for 350 min. Venous blood samples were drawn and assayed for plasma concentration. The pharmacokinetics were analysed using a nonlinear mixed-effect model with an interindividual and intraindividual error model. An initial estimation was performed to determine which of the one-, two- or three-compartment models is best to describe the concentration-time data. The covariates age, gender, weight, height, lean body mass (LBM), body surface area (BSA) and body mass index (BMI) were tested for significant effects on parameters using a stepwise forward addition and backward elimination approach. Covariate effects were judged based on changes in the objective function value (OFV).

RESULTS

The pharmacokinetics of dexmedetomidine were best described by a three-compartment model. The model was further improved when height was a covariate of systemic clearance (Cl1), with a decrease in OFV by -13.56 (P<0.01). From the heights of 155-178 cm, Cl1 increased by approximately 143%. The final pharmacokinetic parameter values were as follows: V1 =63.4 l, V2=41.3 l, V3 =284.3 l, Cl1=0.47×(height/160 cm)(6.42) l/min, Cl2=2.43 l/min and Cl3=0.086 l/min.

CONCLUSIONS

This study identified (i) the effect of height on the pharmacokinetics of dexmedetomidine; (ii) that there is no influence of age, gender, weight, LBM, BSA and BMI on pharmacokinetic parameters; and (iii) it established a preliminary population pharmacokinetic model for Chinese patients.

Highly efficient virus resistance mediated by artificial microRNAs that target the suppressor of PVX and PVY in plants

MicroRNAs (miRNAs) processed from nuclear-encoded transcripts control expression of target transcripts by directing cleavage or translational inhibition. Artificial miRNAs (amiRNAs) that exploit this endogenous gene silencing mechanism can be designed to target any gene of interest and provide a highly specific approach for effective post-transcriptional gene silencing (PTGS) in plants. Here, using Arabidopsis thaliana miR159a, miR167b and miR171a precursors as backbones, we designed two types of amiRNA targeting sequence that encode the silencing suppressor HC-Pro of Potato virus Y (PVY) and the TGBp1/p25 (p25) of Potato virus X (PVX). The detected amiRNAs efficiently inhibited HC-Pro and p25 gene expression and conferred highly specific resistance against PVY or PVX infection in transgenic Nicotiana tabacum; this resistance was also maintained under conditions of increased viral pressure. Moreover, resistance was strongly influenced by the complementarity between the target sequence and amiRNA, and was well correlated to amiRNA expression level; the expression level of amiRNAs was also well related to the precursor backbones. We further showed that transgenic N. tabacum developed highly effective resistance to both PVY and PVX through expression of a dimeric amiRNA precursor. Together, our findings indicate that transgenic plants with multiple virus-specific resistance can be obtained through co-expression of several amiRNAs targeting multiple viruses.

The CKLF1-C19 peptide attenuates allergic lung inflammation by inhibiting CCR3- and CCR4-mediated chemotaxis in a mouse model of asthma

BACKGROUND

  Human chemokine-like factor 1 (CKLF1) is a functional ligand for human CCR4, which is highly expressed on Th2 lymphocytes and plays an important role in the pathogenesis of asthma. The expression and function of CKLF1 are associated with asthma. The CKLF1 C-terminal peptides C19 and C27 also interact with human CCR4. Albeit with weaker chemotactic activity, C19 can inhibit chemotaxis induced by both CKLF1 and CCL17. Here, we explore whether C19 can act as an antagonist in the development of asthma.

METHODS

  A mouse model of asthma and in vitro and in vivo chemotaxis assays were used.

RESULTS

  Using a mouse model of asthma, we demonstrate here that C19 reduces airway eosinophilia, lung inflammation and airway hyperresponsiveness; in contrast, C27 has little effect on these parameters. The inhibitory effects of C19 on CCR4-mediated chemotaxis could be observed in human Th2 lymphocytes and in the splenocytes from ovalbumin-sensitized mice. Furthermore, we show that C19 can inhibit CCL11-induced chemotaxis of mouse eosinophils and human CCR3-transfected or mouse Ccr3-transfected HEK293 cells. In vivo chemotaxis assays revealed that C19 and C27 can reduce CCL11-mediated recruitment of eosinophils into the peritoneal cavity and that this inhibitory effect is stronger for C19 than for C27.

CONCLUSIONS

  Thus, C19 can attenuate airway eosinophilia and lung inflammation by inhibiting CCR3- and CCR4-mediated chemotaxis in a mouse model of asthma. Given its ability to inhibit human CCR3- and CCR4-meditated chemotaxis, C19 has great therapeutic potential for use in the treatment and control of allergic asthma.

Distribution and dynamics of Bemisia tabaci invasive biotypes in central China

The tobacco whitefly, Bemisia tabaci (Gennadius), causes severe crop losses in many agricultural systems. The worst of these losses are often associated with the invasion and establishment of specific whitefly biotypes. In a comprehensive survey of biotypes present in central China between 2005 and 2007, we obtained 191 samples of B. tabaci from 19 districts in Hubei province and its surrounds. Biotypes were identified by RAPD-PCR and by sequencing the mitochondrial cytochrome oxidase I gene (mtCO1). We determined that these central Chinese haplotypes included the world's two most invasive B. tabaci biotypes (B and Q) and two indigenous biotypes (ZHJ1 and ZHJ3). The B biotype shared >99.7% identity with other Chinese B biotypes and the Q biotype shared >99.5% of its identity with Q samples from the Mediterranean, USA, Africa and East Asia. By 2007, the Q biotype was dominant over much of Hubei province and appeared to be supplanting all other biotypes, although both the invasive and indigenous biotypes existed in sympatry in some regions. The invasion and rapid establishment of the Q biotype in China mirrors events elsewhere in the world, and we suggest that this is a consequence of its reproductive isolation, its polyphagous nature and its broad-spectrum resistance to insecticides. Its dominance has severe implications for the sustainability of some insecticide groups and for the production of a number of crops.

Kashin-Beck disease and Sayiwak disease in China: prevalence and a comparison of the clinical manifestations, familial aggregation, and heritability

OBJECTIVE

To compare the prevalence, the clinical manifestations, familial aggregation and heritability of Kashin-Beck disease (KBD) and Sayiwak disease (SD) in China.

METHODS

10,823 people from 1361 families in 14 villages in Linyou County, Shaanxi Province, were examined for KBD, and 2264 people from 552 families in Sayiwak village, Kashi city, Xinjiang, were examined for SD. The investigation included documentation of individual information and clinical manifestations. Patients were subject to radiographic imaging of the right hand. t-Tests and chi-square tests were used to examine correlations of the diseases with age and gender in each of the two groups. Analysis of familial aggregation was conducted with the chi-square distribution analysis of goodness of fit using the SAS8.0 program. The Li-Mantel-Gart method was employed for the segregation analysis. The Falconer regression method11 was employed to estimate heritability (h²).

RESULTS

The prevalence of KBD in Linyou County was 10.90%, and of SD in Sayiwak village was 0.57%. Of the 21 clinical signs examined, KBD cases exhibited 19 signs (90.48%) and SD cases exhibited 18 signs (85.71%), which indicate similarities between the two diseases. However, different clinical signs were evident between the KBD and SD cases, with different impairment rates among joints of limbs in KBD and similar rates in SD. A comparison of radiological features of limb arthropathy between the two diseases showed differences in several characteristics between the two diseases. In addition, measurements of stature and sitting height showed significant differences in bone development between the two diseases. For KBD cases, the values of h² in the first-degree and the second-degree relatives were 41.76% and 37.20% (P<0.05). The CI of h² was 31.17-52.38 and 19.86-54.55, with a segregation ratio of P=0.12, SE(P)=0.014, 95%CI 0.09-0.15, less than 0.25(χ²=42.36, df=1, P<0.001). For SD cases, the values of h² were 155.61%, 273.63% and 236.83%. The 95% CIs of h² were 133.20-178.12, 229.83-317.42 and 145.83-327.81, respectively, with a segregation ratio of P=0.34, SE(P)=0.059, and CIs between 0.22 and 0.45(χ²=4.9817, df=1, P>0.05).

CONCLUSION

The results indicate both similarities and differences in the clinical manifestations of KBD and SD. However, environmental factors appear to play a major role in KBD, while hereditability is a major factor in SD.

Reactive oxygen species cause endothelial dysfunction in chronic flow overload

Although elevation of shear stress increases production of vascular reactive oxygen species (ROS), the role of ROS in chronic flow overload (CFO) has not been well investigated. We hypothesize that CFO increases ROS production mediated in part by NADPH oxidase, which leads to endothelial dysfunction. In six swine, CFO in carotid arteries was induced by contralateral ligation for 1 wk. In an additional group, six swine received apocynin (NADPH oxidase blocker and anti-oxidant) treatment in conjunction with CFO for 1 wk. The blood flow in carotid arteries increased from 189.2 ± 25.3 ml/min (control) to 369.6 ± 61.9 ml/min (CFO), and the arterial diameter increased by 8.6%. The expressions of endothelial nitric oxide synthase (eNOS), p22/p47(phox), and NOX2/NOX4 were upregulated. ROS production increased threefold in response to CFO. The endothelium-dependent vasorelaxation was compromised in the CFO group. Treatment with apocynin significantly reduced ROS production in the vessel wall, preserved endothelial function, and inhibited expressions of p22/p47phox and NOX2/NOX4. Although the process of CFO remodeling to restore the wall shear stress has been thought of as a physiological response, the present data implicate NADPH oxidase-produced ROS and eNOS uncoupling in endothelial dysfunction at 1 wk of CFO.

A recombinant rabies virus expressing luciferase

A recombinant Rabies virus (RV) expressing firefly luciferase (rRV-luc) was generated by an improved reverse genetics system. Its biological properties were compared with those of the parental RV. The rRV-luc grew in BHK-21 cells similarly to RV, but its virulence for mice was weaker as shown by the lower infectious titers in brain. Rising infectious titers of rRV-luc during its passaging in BHK-21 cells indicated a virus adaptation, while the luciferase (luc) expression was stable. These results suggest that the recombinant RV carrying luc gene might prove a useful tool for further analysis of pathogenesis of RV in small animal models.

The 32-year relationship between cholesterol and dementia from midlife to late life

BACKGROUND

Cellular and animal studies suggest that hypercholesterolemia contributes to Alzheimer disease (AD). However, the relationship between cholesterol and dementia at the population level is less clear and may vary over the lifespan.

METHODS

The Prospective Population Study of Women, consisting of 1,462 women without dementia aged 38-60 years, was initiated in 1968-1969 in Gothenburg, Sweden. Follow-ups were conducted in 1974-1975, 1980-1981, 1992-1993, and 2000-2001. All-cause dementia was diagnosed according to DSM-III-R criteria and AD according to National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria. Cox proportional hazards regression examined baseline, time-dependent, and change in cholesterol levels in relation to incident dementia and AD among all participants. Analyses were repeated among participants who survived to the age of 70 years or older and participated in the 2000-2001 examination.

RESULTS

Higher cholesterol level in 1968 was not associated with an increased risk of AD (highest vs lowest quartile: hazard ratio [HR] 2.82, 95% confidence interval [CI] 0.94-8.43) among those who survived to and participated in the 2000-2001 examination. While there was no association between cholesterol level and dementia when considering all participants over 32 years, a time-dependent decrease in cholesterol over the follow-up was associated with an increased risk of dementia (HR 2.35, 95% CI 1.22-4.58).

CONCLUSION

These data suggest that midlife cholesterol level is not associated with an increased risk of AD. However, there may be a slight risk among those surviving to an age at risk for dementia. Declining cholesterol levels from midlife to late life may better predict AD risk than levels obtained at one timepoint prior to dementia onset. Analytic strategies examining this and other risk factors across the lifespan may affect interpretation of results.

The glutaminergic, GABAergic, dopaminergic but not cholinergic neurons are susceptible to anaesthesia-induced cell death in the rat developing brain

Neuronal cell death induced by anaesthetics in the developing brain was evident in previous pre-clinical studies. However, the neuronal cell types involved in anaesthesia-induced neuronal cell death remains elusive. The aim of this study was to investigate glutamatergic, GABAergic, cholinergic and dopaminergic neuronal cell apoptosis induced by anaesthetic exposure in specific brain regions in rats. Separate cohorts of 7-day-old Sprague Dawley (SD) rat pups were randomly assigned to two groups: Naive and anaesthetics alone (70% nitrous oxide and 0.75% isoflurane exposure for 6 h). The brains were sectioned and the slices that contained the basal forebrain, substantia nigra, cornu ammonis area 1 (CA1) subarea of hippocampus or cingulate cortex were selected and subsequently subjected to double-labelled fluorescent immunohistochemistry for choline acetyltransferase, dopamine, vesicular glutamate transporter 1 (vGLUT1) or glutamic acid decarboxylase 67 (GAD67) together with caspase 3, respectively. Compared to the naive control, anaesthetic exposure significantly increased the number of caspase-3 positive cells in the CA1 subarea of hippocampus, cingulate cortex, and substantia nigra, but not in the basal forebrain. 54% and 14% of apoptotic cells in the CA1 subarea of hippocampus were GABAergic and glutamatergic neurons respectively. In the cingulate cortex, 30% and 37% of apoptotic cells were GABAergic and glutamatergic neurons respectively. In the substantia nigra, 22% of apoptotic cells were dopaminergic neurons. Our data suggests, anaesthetic exposure significantly increases neuroapoptosis of glutamatergic, GABAergic and dopaminergic neurons in the developing brain but not that of the cholinergic neurons in the basal forebrain.

A novel single nucleotide polymorphism (SNP) of the <i>IGF1R</i> gene and the association with growth traits in yak (Brief Report)

Abstract. The insulin-like growth factor-I (IGF1) is a peptide growth factor that exerts mitogenic and metabolic activities, which are regulators of growth, survival and cell differentiation in a number of cell and tissue types. To elicit its effects, IGF1 must bind its receptors. The insulinlike growth factor 1 receptor (IGF1R) is similar to insulin receptor (INSR) and it mediates the growth-promoting effect of IGF1. The IGF1R gene, therefore, was selected as a biological candidate gene for growth, body composition, metabolic, and skeletal traits in animals (Rothschild et al. 1997). By now, no polymorphism of yak (Bos grunniensL) IGF1R gene is reported. In the present paper, the partial exon 1 region of IGF1R was screened to detect the SNPs in Chinese yak breeds. Associations of SNP of IGF1R with growth traits were analysed.

Secular changes in cognitive predictors of dementia and mortality in 70-year-olds

BACKGROUND

Successive elderly birth cohorts improved in cognitive performance during the 20th century. It is not clear whether this influences cognitive predictors of dementia and mortality.

OBJECTIVE

In 2 longitudinal population studies, representing 2 cohorts of 70-year-olds examined 30 years apart, we investigated the relation between baseline cognitive function and 5-year occurrence of dementia and mortality.

METHODS

Two representative cohorts of 70-year-olds initially free from dementia born in 1901-1902 (cohort 1901-1902: n = 381) and 1930 (cohort 1930: n = 551) from Gothenburg, Sweden, were examined in 1971-1972 and 2000-2001 and after 5 years for the outcome of dementia and death. Recent memory was evaluated during psychiatric examinations, and nonmemory domains using psychometric tests.

RESULTS

At age 70, cohort 1930 performed better on psychometric tests, and had fewer recent memory problems compared to cohort 1901-1902. During 5-year follow-up, 5.0% in cohort 1901-1902 and 4.4% in cohort 1930 (p = 0.742) developed dementia, and 15.7% in cohort 1901-1902 and 4.4% in cohort 1930 died (p < 0.001). Recent memory was associated with incident dementia in both cohorts. Low scores in nonmemory tests were associated with incident dementia in cohort 1901-1902, but not in cohort 1930. Recent memory problems and lower scores in nonmemory tests were associated with 5-year mortality in cohort 1901-1902, but not in cohort 1930.

CONCLUSIONS

Secular changes in cognitive performance may influence cognitive predictors of dementia and mortality, despite similar incidence of dementia. The findings should be taken cautiously due to differences between cohorts in refusal rates, quality of education, and dementia recognition in medical records.

Mitochondrial function is altered in articular chondrocytes of an endemic osteoarthritis, Kashin-Beck disease

OBJECTIVE

Kashin-Beck disease (KBD) is an endemic degenerative osteoarthritis (OA) associated with extracellular matrix degradation and chondrocyte necrosis in the articular and growth plate cartilage. The role of mitochondria in degenerative diseases is widely recognized but its function in KBD is unknown. The aim of this investigation was to evaluate mitochondrial function to understand the mitochondria-mediated caspase activation and apoptosis in adult KBD chondrocytes.

METHODS

Mitochondrial function was evaluated by analyzing the activities of respiratory chain enzyme complexes and citrate synthase (CS), intracellular adenosine triphosphate (ATP) contents, as well as changes in mitochondrial membrane potential (DeltaPsim). Apoptotic cell death was evaluated by analyzing the cytochrome c release from mitochondria to the cytosol, caspase-9 and 3 activities, and the apoptosis rate of KBD articular chondrocytes.

RESULTS

Activities of complexes II, III, IV and V were reduced in KBD articular chondrocytes compared with cells from normal controls. However, the mitochondrial mass was increased in KBD samples. Cultured KBD chondrocytes had a reduction of cellular ATP levels and contained a higher proportion of cells with de-energized mitochondria. Mitochondrial cytochrome c release and activation of caspase-9 and 3 were also observed. The percentages of positive apoptotic chondrocytes from the KBD patient group stained by Hoechst nuclear stain and Annexin V/PI for flow cytometry exhibited higher levels than that of the healthy controls.

CONCLUSION

These findings suggest the involvement of mitochondrial function and apoptotic cell death in the pathophysiology of KBD. The dysfunction of the mitochondria may play an important role in KBD articular chondrocytes apoptosis.

Effects of TGF-beta3 and preculture period of osteogenic cells on the chondrogenic differentiation of rabbit marrow mesenchymal stem cells encapsulated in a bilayered hydrogel composite

In this work, injectable, biodegradable hydrogel composites of crosslinked oligo(poly(ethylene glycol) fumarate) and gelatin microparticles (MPs) were used to fabricate a bilayered osteochondral construct. Rabbit marrow mesenchymal stem cells (MSCs) were encapsulated with transforming growth factor-beta3 (TGF-beta3)-loaded MPs in the chondrogenic layer and cocultured with cells of different periods of osteogenic preculture (0, 3, 6 and 12 days) in the osteogenic layer to investigate the effects of TGF-beta3 delivery and coculture on the proliferation and differentiation of cells in both layers. The results showed that, in the chondrogenic layer, TGF-beta3 significantly stimulated chondrogenic differentiation of MSCs. In addition, cells of various osteogenic preculture periods in the osteogenic layer, along with TGF-beta3, enhanced gene expression for MSC chondrogenic markers to different extents. In the osteogenic layer, cells maintained their alkaline phosphatase activity during the coculture; however, mineralization was delayed by the presence of TGF-beta3. Overall, this study demonstrated the fabrication of bilayered hydrogel composites which mimic the structure and function of osteochondral tissue, along with the application of these composites as cell and growth factor carriers, while illustrating that encapsulated cells of different degrees of osteogenic differentiation can significantly influence the chondrogenic differentiation of cocultured progenitor cells in both the presence and absence of chondrogenic growth factors.

Avidity of thyroglobulin antibody in sera from patients with Hashimoto's thyroiditis with different thyroid functional status

The mechanism of disease progression in Hashimoto's thyroiditis (HT) is still unclear. Thyroglobulin antibody (TgAb) is a diagnostic hallmark of HT. The aim of our study was to evaluate the avidity of TgAb in sera from HT patients with different thyroid functional status. Sera from 50 patients with newly diagnosed HT were collected and divided into three groups according to thyroid function: patients with hypothyroidism (H, n=18), subclinical hypothyroidism (sH, n=18) and euthyroidism (Eu, n=14). Titres and avidity of TgAb were determined by enzyme-linked immunosorbent assays (ELISAs). Avidity constant (aK) was determined as the reciprocal value of the thyroglobulin molar concentration in the liquid phase resulting in 50% inhibition of TgAb binding to thyroglobulin in solid-phase ELISAs. The titres and aK of TgAb were performed using log-transformation, and expressed as lgT and lgaK, respectively. Mean lgT of TgAb in sera was 4.19+/-0.60 in H, 3.77+/-0.63 in sH, and 3.29+/-0.64 in Eu, respectively. The median avidity of TgAb was 2.30x10(9) in H, 8.80x10(8) in sH, 2.00x10(7) in Eu, respectively. lgT and lgaK of TgAb were at significantly lower levels in Eu than in sH and H (P<0.05). Correlation was found between lgT and lgaK (r=0.594, P<0.05). lgaK was also related to TSH (r=0.308, P<0.05). Our study indicated that patients with high-avidity TgAb might be at high risk of developing subclinical, even to overt, hypothyroidism.

Heritability estimates and linkage analysis of 23 short tandem repeat loci on chromosomes 2, 11, and 12 in an endemic osteochondropathy in China

OBJECTIVE

To estimate the heritability of Kashin-Beck disease (KBD) in first-degree relatives and to identify chromosome regions likely to contain susceptibility loci for KBD.

METHODS

A total of 331 probands with confirmed KBD in their pedigrees were selected from 9331 residents in 17 KBD villages of Linyou county, northwestern China. The heritability (h(2)) in first-degree relatives was estimated by using Falconer's formula. The segregation ratio was calculated by the Li-Mantel-Gart method. A total of 23 short tandem repeat (STR) loci on chromosomes 2, 11, and 12 were used to identify the susceptibility genes for KBD by linkage analysis using the GENEHUNTER program in 19 KBD pedigrees.

RESULTS

The general prevalence rate of KBD was 13.75% in the 17 KBD villages, lower than that of 20.88% in the first-degree relatives of the KBD probands. In the first-degree relatives, the heritability was 0.064 and the segregation ratio 35.10% (p < 0.05). Slight evidence for heritability was detected only in locus D12S1725 with a logarithm of odds (LOD) score of 1.95. However, the nonparametric linkage (NPL) scores showed no linkage between KBD and the 23 loci; the maximum NPL score was 1.59 for locus D12S1725.

CONCLUSIONS

Our results show that 35.10% of the heritability is attributable to genetic variation for the KBD phenotype among individuals of Linyou county, and the segregation ratio supports a multifactorial inheritance of KBD. There is no significant linkage between KBD and the 23 markers in the Linyou population examined; however, markers near the locus D12S1725 may indicate loci for further study.