Hypotension and hypothalamic amine metabolism after long-term alpha-methyldopa infusions.

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.     

Cytogenetic,hybridization and molecular evidence of four cytological forms of Anopheles nigerrimus (Hyrcanus Group) in Thailand and Cambodia

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)].     

Biochemical Characterization of α-Adrenergic Receptors in Human Brain and Changes in Alzheimer-Type Dementia

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.     

Up-Regulation of Immunolabeled α2A-Adrenoceptors, Gi Coupling Proteins, and Regulatory Receptor Kinases in the Prefrontal Cortex of Depressed Suicides

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 (G_i 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 α_2A-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 α_2A-adrenoceptors, Gα_1/2 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 α_2A-adrenoceptors (31-40%), Gα_1/2 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 α_2A-adrenoceptors and Gα_1/2 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 Gα_1/2 proteins (32%), but with modest decreases in the levels of α_2A-adrenoceptors (6%) and GRK 2/3 (18%) in brains of depressed suicide victims. The increased levels in concert of α_2A-adrenoceptors, Gα_1/2 proteins, and GRK 2/3 in brains of depressed suicide victims support the existence of supersensitive α_2A-adrenoceptors in subjects with major depression.     

A Novel Approach to Optimize and Formulate Fast Disintegrating Tablets for Nausea and Vomiting

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.     

Optimization of polylactic-co-glycolic acid nanoparticles containing itraconazole using 2<Superscript>3</Superscript> factorial design

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.     

Response surface methodology for optimization and characterization of limonene-based coenzyme Q10 self-nanoemulsified capsule dosage form

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.     

Increased 5-HT3-mediated signalling in pelvic afferent neurons from mice deficient in P2X2 and/or P2X3 receptor subunits

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.     

L-Dopa and the Albino Riddle: Content of L-Dopa in the Developing Retina of Pigmented and Albino Mice

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-tyr^c2j) 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.     

Experimental studies on a kinetic model for design and operation of activated sludge processes

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 = X_R/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, X_R 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 X^R at 10,000 mg/liter. Also, values of maximum specific growth rate, μ_max, and saturation constant, K_s 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.     

The Point Evaluation Method for Approximating Function Means,Variances and Covariances

A perennial problem in statistics is the determination of biases, variances and covariances for functions of random variables X₁, X₂, …, X_n 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, …, X_n = = μ_n μ_n, where μ_i is the mean and σ_i 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.     

On Asymptotically Distribution-Free Confidence Bounds for P (X1≥X2) Based on Samples not Necessarily Independent

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 X_j. 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.     

Cytogenetic,cross-mating and molecular evidence of four cytological races of Anopheles crawfordi (Diptera: Culicidae) in Thailand and Cambodia

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).     

A Distribution-Free Two-Sample Equivalence Test Allowing for Tied Observations

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.     

SYNTHETIC HYBRIDS OF NEW WORLD AND OLD WORLD AGROPYRONS: III. AGROPYRON REPENS × TETRAPLOID AGROPYRON SPICATUM

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.     

SYNTHETIC AGROPYRON-ELYMUS HYBRIDS: III. ELYMUS CANADENSIS X AGROPYRON CANINUM,A. TRACHYCAULUM,AND A. STRIATUM

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.     

Conserved autonomy of replication of the X-chromosomes in hybrids of Drosophila miranda and Drosophila persimilis

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.