共查询到20条相似文献,搜索用时 31 毫秒
1.
In an effort to identify the metabolite of α-methyldopa (α-MD) most responsible for the hypotensive effect of the drug, we infused α-MD (2–20 mg/kg/hr) into the jugular vein of normotensive, conscious, restrained male Sprague-Dawley rats. Changes in blood pressure were measured after 24 hr of drug infusion. Steady-state turnover was then determined by switching infusions to identical doses of deuterated α-MD (2,5,6-α-MD-d3) and the rate of incorporation of deuterium into the metabolites α-methyldopamine (α-MDA) and α-methylnorepinephrine (α-MNE) was followed. Results show that blood pressure reduction correlated with α-MDA concentration but not with α-MNE concentration or turnover rate. 相似文献
2.
Siripan Songsawatkiat Visut Baimai Atiporn Saeung Sorawat Thongsahuan Yasushi Otsuka Wichai Srisuka Wej Choochote 《Journal of vector ecology》2013,38(2):266-276
Thirteen isoline colonies of Anopheles nigerrimus were established from individual wild‐caught females collected from cow‐baited traps at locations in Thailand and Cambodia. Three types of X (X1, X2, X3) and 4 types of Y (Y1, Y2, Y3, Y4) chromosomes were recovered, according to differing amounts of extra heterochromatin. Four karyotypic forms were designed depending upon apparently distinct figures of X and Y chromosomes, i.e., Form A (X1, X2, X3, Y1), B (X2, X3, Y2), C (X1, Y3), and D (X3, Y4). Forms C and D were new metaphase karyotypes discovered in this study. Form A appeared to be common in both Thailand and Cambodia. Forms B and D were found to be rather specific to southern and northeastern Thailand, respectively, whereas Form C was confined to Cambodia. Hybridization experiments among the eight isoline colonies, which were representative of four karyotypic forms of An. nigerrimus, demonstrated genetic compatibility in giving viable progenies and synaptic salivary gland polytene chromosomes through F2‐generations. These results elucidated the conspecific relationship, comprising four cytological forms within this taxon. Supportive evidence was confirmed further by very low intraspecific sequence variations (average genetic distance = 0.002–0.007) of the nucleotide sequences in ribosomal DNA [second internal transcribed spacer (ITS2)] and mitochondrial DNA [cytochrome c oxidase subunit I (COI) and subunit II (COII)]. 相似文献
3.
Biochemical Characterization of α-Adrenergic Receptors in Human Brain and Changes in Alzheimer-Type Dementia 总被引:2,自引:2,他引:0
Shun Shimohama Takashi Taniguchi Motohatsu Fujiwara Masakuni Kameyama 《Journal of neurochemistry》1986,47(4):1294-1301
Abstract Using ligand binding techniques, we studied α-adrenergic receptors in brains obtained at autopsy from seven histologically normal controls and seven patients with histopathologically verified Alzheimer-type dementia (ATD). Binding of the α-adrenergic antagonists [3H]prazosin and [3H]yohimbine to membranes of human brains exhibited characteristics compatible with α1- and α2-adrenergic receptors, respectively. Binding of both ligands was saturable and reversible, with dissociation constants of 0.15 nM for [3H]prazosin and 5.5 nM for [3H]yohimbine. [3H]Prazosin binding was highest in the hippocampus and frontal cortex and lowest in the caudate and putamen in the control brains. [3H]Yohimbine binding was highest in the nucleus basalis of Meynert (NbM) and frontal cortex and lowest in the caudate and cerebellar hemisphere in the control brains. Compared with values for the controls, [3H]prazosin binding sites were significantly reduced in number in the hippocampus and cerebellar hemisphere, and [3H]yohimbine binding sites were significantly reduced in number in the NbM in the ATD brains. These results suggest that α1 and α2-adrenergic receptors are present in the human brain and that there are significant changes in numbers of both receptors in selected regions in patients with ATD. 相似文献
4.
Jesús A. García-Sevilla† Pablo V. Escribᆠrés Ozaita† Romano La Harpe‡ Claude Walzer Ariel Eytan & José Guimón 《Journal of neurochemistry》1999,72(1):282-291
Abstract : Suicide and depression are associated with an increased density of α2-adrenoceptors (radioligand receptor binding) in specific regions of the human brain. The function of these inhibitory receptors involves various regulatory proteins (Gi coupling proteins and G protein-coupled receptor kinases, GRKs), which work in concert with the receptors. In this study we quantitated in parallel the levels of immunolabeled α2A-adrenoceptors and associated regulatory proteins in brains of suicide and depressed suicide victims. Specimens of the prefrontal cortex (Brodmann area 9) were collected from 51 suicide victims and 31 control subjects. Levels of α2A-adrenoceptors, Gα1/2 proteins, and GRK 2/3 were assessed by immunoblotting techniques by using specific polyclonal antisera and the immunoreactive proteins were quantitated by densitometry. Increased levels of α2A-adrenoceptors (31-40%), Gα1/2 proteins (42-63%), and membrane-associated GRK 2/3 (24-32%) were found in the prefrontal cortex of suicide victims and antidepressantfree depressed suicide victims. There were significant correlations between the levels of GRK 2/3 (dependent variable) and those of α2A-adrenoceptors and Gα1/2 proteins (independent variables) in the same brain samples of suicide victims (r = 0.56, p = 0.008) and depressed suicide victims (r = 0.54, p = 0.041). Antemortem antidepressant treatment was associated with a significant reduction in the levels of Gα1/2 proteins (32%), but with modest decreases in the levels of α2A-adrenoceptors (6%) and GRK 2/3 (18%) in brains of depressed suicide victims. The increased levels in concert of α2A-adrenoceptors, Gα1/2 proteins, and GRK 2/3 in brains of depressed suicide victims support the existence of supersensitive α2A-adrenoceptors in subjects with major depression. 相似文献
5.
The aim of this study was to optimize and formulate fast disintegrating tablets (FDTs) for nausea and vomiting using aminoacetic
acid, carmellose and sodium alginate with enough mechanical strength. Ondansetron HCl (water soluble) or domperidone (water
insoluble) drug were added to FDTs and their disintegration behaviour was evaluated. Plackett Burman Screening Design was
used to screen the independent active process variables [concentration of aminoacetic acid (X
1), concentration of carmellose (X
2) and tablet crushing strength (X
3)] which were found to actively influence the dependent variables [disintegration time in the mouth (DT), wetting time (WT),
and water absorption ratio (WAR)] for both the drugs. Also, the coefficients of active variables (DT, WT and WAR) of FDTs
containing domperidone was found to be significantly different (P < 0.05) from the coefficients of active factors (X
1, X
2 and X
3) containing ondansetron HCl FDTs. Further, FDTs containing domperidone was prepared according to central composite design
for estimating the effect of active factors (X
1, X
2, X
3) in extended spherical domain. The regression analysis of quadratic fit revealed that DT, WT and WAR were 98% correlated
with active factors (X
1, X
2 or X
3). The optimized domperidone FDTs were further compared with superdisintegrants (croscarmellose sodium or crospovidone). The
data revealed that optimized domperidone FDTs were better than domperidone FDTs containing croscarmellose or crospovidone.
Hence, this novel excipients combination can be used for delivery of water insoluble drugs in place of superdisintegrants. 相似文献
6.
This study investigated the utility of a 23 factorial design and optimization process for polylactic-co-glycolic acid (PLGA) nanoparticles containing itraconazole with
5 replicates at the center of the design. Nanoparticles were prepared by solvent displacement technique with PLGAX
1 (10, 100 mg/mL), benzyl benzoateX
2 (5, 20 μg/mL), and itraconazoleX
3 (200, 1800 μg/mL). Particle size (Y
1), the amount of itraconazole entrapped in the nanoparticles (Y
2), and encapsulation efficiency (Y
3) were used as responses. A validated statistical model having significant coefficient figures (P<.001) for the particle size (Y
1), the amount of itraconazole entrapped in the nanoparticles (Y
2), and encapsulation efficiency (Y
3) as function of the PLGA (X
1), benzyl benzoate (X
2), and itraconazole (X
3) were developed: Y1=373.75+66.54X1+52.09X2+105.06X3−4.73X1X2+46.30X1X3; Y2=472.93+73.45X1+ 169.06X2+333.03X3+62.40X1X3+141.49X2X3; Y3= 57.36+6.53X1+15.52X2−12.59X3+1.01X1X3+ 1.73X2X3.X
1,X
2, andX
3 had a significant effect (P<.001) onY
1,Y
2, andY
3. The particle size, the amount of itraconazole entrapped in the nanoparticles, and the encapsulation efficiency of the 4
formulas were in agreement with the predictions obtained from the models (P<.05). An overlay plot for the 3 responses shows the boundary in whichY
1 shows the boundary in which a number of combinations of concentration of PLGA, benzyl benzoate, and itraconazole will result
in a satisfactory process. Using the desirability approach with the same constraints, the solution composition having the
highest overall desirability (D=0.769) was 10 mg/mL of PLGA, 16.94 μg/mL of benzyl benzoate, and 1001.01 μg/mL of itraconazole.
This approach allowed the selection of the optimum formulation ingredients for PLGA nanoparticles containing itraconazole
of 500 μg/mL. 相似文献
7.
8.
The aim of this study was to systematically obtain a model of factors that would yield an optimized self-nanoemulsified capsule
dosage form (SNCDF) of a highly lipophilic model compound, Coenzyme Q10 (CoQ). Independent variables such as amount of R-(+)-limonene
(X
1), surfactant (X
2), and cosurfactant (X
3), were optimized using a 3-factor, 3-level Box-Behnken statistical design. The dependent variables selected were cumulative
percentage of drug released after 5 minutes (Y
1) with constraints on drug release in 15 minutes (Y
2), turbidity (Y
3), particle size (Y
4), and zeta potential (Y
5). A mathematical relationship obtained,Y
1=78.503+6.058X
1 +13.738X
2+5.986X
3−25.831X
1
2
+9.12X
1X2−26.03X
1X3−38.67X
2
2
+11.02X
2X3−15.55X
3
3
(r
2=0.97), explained the main and quadratic effects, and the interaction of factors that affected the drug release. Response
surface methodology (RSM) predicted the levels of factorsX
1,X
2, andX
3 (0.0344, 0.216, and 0.240, respectively), for a maximized response ofY
1 with constraints of >90% release onY
2. The observed and predicted values ofY
1 were in close agreement. In conclusion, the Box-Behnken experimental design allowed us to obtain SNCDF with rapid (>90%)
drug release within 5 minutes with desirable properties of low turbidity and particle size. 相似文献
9.
Increased 5-HT3-mediated signalling in pelvic afferent neurons from mice deficient in P2X2 and/or P2X3 receptor subunits 总被引:1,自引:0,他引:1
Extracellular ATP and 5-hydroxytryptamine (5-HT) are both involved in visceral sensory pathways by interacting with P2X and 5-HT3 receptors, respectively. We have investigated the changes in P2X and 5-HT3-mediated signalling in pelvic afferent neurons in mice deficient in P2X2 and/or P2X3 subunits by whole-cell recording of L6–S2 dorsal root ganglion (DRG) neurons and by multi-unit recording of pelvic afferents of the colorectum. In wildtype DRG neurons, ATP evoked transient, sustained or mixed (biphasic) inward currents. Transient currents were absent in P2X3
−/− neurons, whereas sustained currents were absent in P2X2
−/− DRG neurons. Neither transient nor sustained currents were observed following application of ATP or α,β-methylene ATP (α,β-meATP) in P2X2/P2X3
Dbl−/− DRG neurons. 5-HT was found to induce a fast inward current in 63% of DRG neurons from wildtype mice, which was blocked by tropisetron, a 5-HT3 receptor antagonist. The percentage of DRG neurons responding to 5-HT was significantly increased in P2X 2
−/−, P2X3
−/− and P2X2/P2X3
Dbl−/− mice, and the amplitude of 5-HT response was significantly increased in P2X2/P2X3
Dbl−/− mice. The pelvic afferent response to colorectal distension was attenuated in P2X2/P2X3
Dbl−/− mice, but the response to serosal application of 5-HT was enhanced. Furthermore, tropisetron resulted in a greater reduction in pelvic afferent responses to colorectal distension in the P2X2/P2X3
Dbl−/− preparations. These data suggest that P2X receptors containing the P2X2 and/or P2X3 subunits mediate purinergic activation of colorectal afferents and that 5-HT signalling in pelvic afferent neurons is up-regulated in mice lacking P2X2 or P2X3 receptor genes. This effect is more pronounced when both subunits are absent. 相似文献
10.
Suzanne Roffler-Tarlov Jin Hong Liu Elena N. Naumova Maria Margarita Bernal-Ayala Carol A. Mason 《PloS one》2013,8(3)
Background
The absence or deficiency of melanin as in albinos, has detrimental effects on retinal development that include aberrant axonal projections from eye to brain and impaired vision. In pigmented retinal pigment epithelium (RPE), dihydroxyphenalanine (L-Dopa), an intermediate in the synthetic path for melanin, has been hypothesized to regulate the tempo of neurogenesis. The time course of expression of retinal L-Dopa, whether it is harbored exclusively in the RPE, the extent of deficiency in albinos compared to isogenic controls, and whether L-Dopa can be restored if exogenously delivered to the albino have been unknown.Methodology/Principal Findings
L-Dopa and catecholamines including dopamine extracted from retinas of pigmented (C57BL/6J) and congenic albino (C57BL/6J-tyrc2j) mice, were measured throughout development beginning at E10.5 and at maturity. L-Dopa, but not dopamine nor any other catecholamine, appears in pigmented retina as soon as tyrosinase is expressed in RPE at E10.5. In pigmented retina, L-Dopa content increases throughout pre- and postnatal development until the end of the first postnatal month after which it declines sharply. This time course reflects the onset and completion of retinal development. L-Dopa is absent from embryonic albino retina and is greatly reduced in postnatal albino retina compared to pigmented retina. Dopamine is undetectable in both albino and pigmented retinas until after the postnatal expression of the neuronal enzyme tyrosine hydroxylase. If provided to pregnant albino mothers, L-Dopa accumulates in the RPE of the fetuses.Conclusions
L-Dopa in pigmented RPE is most abundant during development after which content declines. This L-Dopa is not converted to dopamine. L-Dopa is absent or at low levels in albino retina and can be restored to the RPE by administration in utero. These findings further implicate L-Dopa as a factor in the RPE that could influence development, and demonstrate that administration of L-Dopa could be a means to rescue developmental abnormalities characteristic of albinos. 相似文献11.
Previous experimentation in our laboratory has shown that the classical theory developed for continuous growth of pure cultures in completely mixed aerobic systems in which the recycle cell concentration factor, c (where c = XR/X), is a selectable system constant, did not provide a suitable model for the heterogeneous (natural) populations of the activated sludge process. Another model was derived in which the recycle cell concentration, XR was employed as a system constant instead of c, and computational analysis was performed. Laboratory pilot plant experimentation was undertaken in order to determine whether a “steady state” in aerator biological solids concentration, X?, and substrate concentration, S?, could be approached under this mode of operation. Studies were performed at various organic feed concentrations holding dilution rate, D, at 0.125 hr?1, hydraulic recycle ratio, α, at 0.25, and XR at 10,000 mg/liter. Also, values of maximum specific growth rate, μmax, and saturation constant, Ks were determined. It was found that the model approached the steady state condition with heterogeneous populations more closely than did the classical model, and the high degree of treatment efficiency predicted by the model was demonstrated experimentally. 相似文献
12.
B. F. J. Manly 《Biometrical journal. Biometrische Zeitschrift》1986,28(8):949-956
A perennial problem in statistics is the determination of biases, variances and covariances for functions of random variables X1, X2, …, Xn which themselves have a known distribution. A common approach is through equations based upon Taylor series approximations but a “point evaluation” method may sometimes be a useful alternative. This involves approximating the multivariate distribution of the X variables by the 2n points given by X1=μ1±1, X2 = μ2 ±2, …, Xn = = μn μn, where μi is the mean and σi the standard deviation of Xi, with appropriate point weights. An advantage over the Taylor series approach is that function derivatives do not have to be explicitely calculated. The point evaluation method is particularly useful in cases where the X variables are uncorrelated. Then the evaluation of the 2n points can be replaced by the evaluation of 2n points. The point evaluation method is illustrated with powers of a normally distributed variable, and with estimation of gene frequencies from ABO blood group frequencies. 相似文献
13.
R. Hilgers 《Biometrical journal. Biometrische Zeitschrift》1981,23(7):627-633
If X1, X2, denote the random variables of measurement under two treatments then the probability P (X1 ≥ X2) is a quantity of great practical interest, especially if we consider both to be measured for the same unity. In this case the random variables cannot be assumed to be independent any longer. The following paper describes a procedure to compute approximate confidence bounds for P (X1 ≥ X2) where correlations between X1, X2 are admitted as well as between replications of the Xj. There is some relation to the FRIEDMAN-statistic with or without repeated measurements and as a special case to the sign-test. Application may be extended to ordinal data. 相似文献
14.
《Comptes rendus biologies》2014,337(11):625-634
Twenty-nine isolines of Anopheles crawfordi were established from wild-caught females collected from cow-baited traps in Thailand and Cambodia. Three types of X (X1, X2, X3) and four types of Y (Y1, Y2, Y3, and Y4) chromosomes were identified, according to differing amounts of extra heterochromatin. These sex chromosomes represent four metaphase karyotypes, i.e., Forms A (X1, X2, X3, Y1), B (X1, X2, X3, Y2), C (X2, Y3) and D (X2, Y4). Forms C and D are novel metaphase karyotypes confined to Thailand, whereas forms A and B appear to be common in both Thailand and Cambodia. Cross-mating experiments between the four karyotypic forms indicated genetic compatibility in yielding viable progenies and synaptic salivary gland polytene chromosomes. The results suggest that the forms are conspecific and A. crawfordi comprises four cytological races, which is further supported by very low intraspecific variation (mean genetic distance = 0.000–0.018) of the nucleotide sequences in ribosomal DNA (ITS2) and mitochondrial DNA sequences (COI, COII). 相似文献
15.
A new testing procedure is derived which enables to assess the equivalence of two arbitrary noncontinuous distribution functions from which unrelated samples are taken as the data to be analyzed. The equivalence region is defined to consist of all pairs (F,G) of distribution functions such that for independent X ∼ F, Y ∼ G the conditional probability of {X > Y} given {X ≠ Y} lies in some short interval around 1/2. The test rejects the null hypothesis of nonequivalence if and only if the standardized distance between the U-statistics estimator of P[X > Y ∣ X ≠ Y] and the center of the equivalence interval (1/2 — ε1, 1/2 + ε2) does not exceed a critical upper bound which has to be computed as the α-quantile of a χ2-distribution with one degree of freedom and a random noncentrality parameter proportional to the squared length of that interval. The test is shown to maintain the asymptotic significance level under very weak regularity conditions. Results of an extensive simulation study suggest that its level properties are very satisfactory in small samples as well. The power turns out to be inversely related to the rate P[X = Y] of ties between observations from different samples. 相似文献
16.
17.
Douglas R. Dewey 《American journal of botany》1967,54(1):93-98
Three hybrids of A. repens, 2n = 42, × A. spicatum, 2n = 28, and two reciprocal hybrids were obtained from emasculated and unemasculated crosses, respectively. The 35-chromosome hybrids tended to be morphologically intermediate between the parent species but resembled A. repens more closely than A. spicatum. A. repens behaved cytologically as a segmental autoallohexaploid, and A. spicatum acted cytologically as an autotetraploid. Mean chromosome associations of 8.04 I, 12.72 II, 0.41 III, 0.06 IV, and 0.009 V were observed in 116 hybrid cells at metaphase I. Most chromosome pairing in the hybrids was attributed to autosyndesis. A. spicatum, A. repens, and their hybrids were represented by genome formulas of SSSS, R1R1X1X1X2X2, and SSR1X1X2, respectively. Hybrid fertility ranged from 0.02 to 0.69 seeds per spikelet. 相似文献
18.
19.
Douglas R. Dewey 《American journal of botany》1968,55(10):1133-1139
Hybrids were produced with relative ease from controlled crosses of Elymus canadensis L. with European Agropyron caninum (L.) Beauv., North American A. trachycaulum (Link) Malte ex H. F. Lewis, and Asian A. striatum Nees ex Steud. All hybrids appeared to be completely sterile and were, for the most part, morphologically intermediate between their parents. The E. canadensis × A. caninum hybrids were exceptionally vigorous and leafy and may have some potential as forage grasses if fertility can be achieved. All parent plants were tetraploid, 2n = 28, and they behaved cytologically as alloploids. Chromosome pairing in the hybrids indicated that both E. canadensis genomes were closely homologous with those of A. trachycaulum and somewhat less homologous with those of A. caninum. Interchanged and inverted chromosome segments apparently constitute the major differences between E. canadensis, A. trachycaulum, and A. caninum genomes; however, cryptic structural differences must also exist. Partial homologies were detected between one A. striatum and E. canadensis genome, but their other genomes were distinctly different. The genome relations between the parent species were expressed in terms of the following genome formulas: E. canadensis, S1S1X1X1; A. trachycaulum, S2S2X2X2; A. caninum, S3S3X3X3 : and A. striatum S4S4YY or X4X4YY, where “S” refers to a genome derived from A. spicatum and “X” and “Y” are genomes of unknown origin. 相似文献
20.
Mausumi Mutsuddi Debasish Mutsuddi A. S. Mukherjee Ashish K. Duttagupta 《Chromosoma》1984,89(1):55-62
The chromosome complement of hybrid males from the cross between Drosophila miranda female and D. persimilis male provides an interesting chromosomal situation where an autosome, the 3rd chromosome of D. persimilis, coexists with a homologue that developed into a sex chromosome, the X2 in D. miranda. Except for certain inversions and a few minor translocations, these two chromosomes (X2 and the 3rd) still look alike as polytene elements. However, in hybrid males pairing of the two chromosomes, the X2 and 3rd, is rare, while in female hybrids it occurs frequently. — 3H-TdR labeling shows that while the X2 and 3rd chromosomes replicate synchronously in hybrid female, in the hybrid male the former completes its replication earlier than the 3rd chromosome, as do the two arms of the X1 (XL and XR). The frequency and relative intensity of 3H-TdR labeling of each site of the X2 and that of the 3rd chromosome in hybrid males closely agree with those of the corresponding sites in the X2 of the miranda male and the 3rd chromosome of the persimilis male (or female), respectively. The results suggest that timing and rate of replication of the X2 are determined autonomously and follow the pattern in the respective parental species. 相似文献