豚鼠眼形觉剥夺后恢复期的生物学参数变化规律探讨

目的探讨豚鼠眼球形觉剥夺后恢复期的生物学参数变化规律。方法普通级2～3周龄豚鼠30只,随机分为两组：①实验组：20只,右眼采用半透明眼罩遮盖进行形觉剥夺4周,随后去遮盖3周,左眼作为自身对照;②正常对照组：10只,双眼不进行任何干预,开放饲养7周。形觉剥夺前、形觉剥夺4周后及去遮盖后第2、6、10、14和21天,测量豚鼠双眼生物学参数：睫状肌麻痹后行带状光检影测量屈光度;A超测量前房深度、晶体厚度和眼轴长度,计算出玻璃体腔长度。结果经过4周形觉剥夺,实验组豚鼠右眼向近视漂移,屈光度为（-2.88±2.30）D,诱导了（-5.50±1.9）D相对近视。去遮盖后,豚鼠右眼重新正视化,屈光度恢复的快速期发生在6 d内,14 d时双眼屈光度差值差异无显著性（t=-2.049,P=0.080）,为（-0.18±0.26）D;右眼玻璃体腔长度缩短,14 d时双眼玻璃体腔长度差值差异无显著性（t=1.652,P=0.14）,为（0.0234±0.0400）mm;右眼眼轴长度缩短,14 d时双眼眼轴长度差值差差异无显著性（t=1.443,P=0.192）,为（0.0183±0.0359）mm。与正常对照组右眼相比,去遮盖6 d,屈光度差异为（-0.48±0.36）D,差异无显著性（t=-1.325,P=0.206）,而2 d时玻璃体腔和眼轴长度差异分别为（0.0961±0.0630）mm、（0.0621±0.0386）mm,差异无显著性（t=1.652,P=0.14;t=1.607,P=0.125）。结论 2～3周龄豚鼠去除形觉剥夺后可以重新进行正视化,伴随玻璃体腔和眼轴长度缩短;去遮盖6 d内为眼生物学参数恢复的主要时期。     

M4受体阻滞剂MT3抑制豚鼠形觉剥夺性近视的探讨

目的探讨高度选择性M4受体阻滞剂MT3对豚鼠形觉剥夺性近视的抑制作用及其潜在作用机理。方法 3周龄豚鼠随机分为三组:对照组、形觉剥夺组、形觉剥夺+MT3组。实验前后使用带状光检影测量屈光度,A超测量眼生物学参数,RT-PCR检测视网膜和脉络膜中TGF-β2的mRNA相对表达量。结果与对照组右眼相比,形觉剥夺+MT3组豚鼠右眼形成了(-1.44±0.50)D相对近视(右眼-左眼),玻璃体腔和眼轴长度分别延长(0.10±0.02)mm和(0.14±0.07)mm(P=0.001,P0.001,P0.001),但近视量、玻璃体腔和眼轴长度增加量均显著小于单纯形觉剥夺组(P0.001,P0.001,P0.001)。单纯形觉剥夺可引起视网膜和脉络膜TGF-β2的mRNA相对表达量下调(P0.001,P=0.014);而玻璃体腔注射MT3可导致形觉剥夺眼视网膜和脉络膜TGF-β2的mRNA相对表达量上调(P0.001,P0.001)。结论 MT3能抑制豚鼠形觉剥夺性近视的形成,其可能通过上调视网膜和脉络膜中TGF-β2的mRNA水平而发挥作用。     

家兔脊髓蛛网膜下腔注射乙酰胆碱对血压和心率的影响

将乙酰胆碱(ACh)注入麻醉家兔脊髓蛛网膜下腔,观察其对心血管活动的影响。结果表明:(1)脊髓蛛网膜下腔注射50～100μg ACh可使血压下降,心率减慢;(2)预先由脊髓蛛网膜下腔注射阿托品,可阻断ACh引起的降压和降心率作用;(3)脊髓蛛网膜下腔注射六甲双铵、酚妥拉明或心得安均不能阻断上述ACh的心血管反应;(4)切断两侧颈部迷走神经,ACh不再使心率减慢,但其降低血压的作用不受到任何影响。 脊髓中ACh水平升高可通过激活胆碱能M-受体引起血压下降和心率减慢。ACh的这种降压作用既没有中枢肾上腺素能受体活动参与,也不是通过迷走神经实现的,可能是由于脊髓交感血管中枢紧张性降低所造成的。     

大鼠脑穹窿下器官微量注射AngⅡ对肾近球小管Na+,K+-ATPase功能的影响

目的：探讨大鼠穹窿下器官（SFO）对外周肾小管钠泵的调节作用及机制。方法：在SFO分别微量注射血管紧张素II（AngII）,其中氯沙坦（losartan）组先用AngII的1型受体（AT1）拮抗剂losartan预处理后再注射AngII 放免法检测血清中内源性洋地黄样物质（EDLS）的水平和血浆AngII水平 微分离大鼠肾脏单根近球小管,液闪法测定小管管周膜钠泵活性。结果：①SFO注射AngII后,血清中EDLS在15 min开始升高,约60 min达高峰 ②肾近球小管钠泵活性在SFO注射AngII后30 min和60 min都显著下降 ③用losartan预处理SFO后,再注射AngII,血清EDLS水平升高和小管钠泵活性下降的效应被显著削弱。结论：大鼠SFO注射AngII后,肾近球小管钠泵活性将下降,原因可能与SFO注射AngII后,激动SFO的AT1受体,直接或间接升高血清EDLS水平有关。     

Effects of branch length uncertainty on Bayesian posterior probabilities for phylogenetic hypotheses

In Bayesian phylogenetics, confidence in evolutionary relationships is expressed as posterior probability--the probability that a tree or clade is true given the data, evolutionary model, and prior assumptions about model parameters. Model parameters, such as branch lengths, are never known in advance; Bayesian methods incorporate this uncertainty by integrating over a range of plausible values given an assumed prior probability distribution for each parameter. Little is known about the effects of integrating over branch length uncertainty on posterior probabilities when different priors are assumed. Here, we show that integrating over uncertainty using a wide range of typical prior assumptions strongly affects posterior probabilities, causing them to deviate from those that would be inferred if branch lengths were known in advance; only when there is no uncertainty to integrate over does the average posterior probability of a group of trees accurately predict the proportion of correct trees in the group. The pattern of branch lengths on the true tree determines whether integrating over uncertainty pushes posterior probabilities upward or downward. The magnitude of the effect depends on the specific prior distributions used and the length of the sequences analyzed. Under realistic conditions, however, even extraordinarily long sequences are not enough to prevent frequent inference of incorrect clades with strong support. We found that across a range of conditions, diffuse priors--either flat or exponential distributions with moderate to large means--provide more reliable inferences than small-mean exponential priors. An empirical Bayes approach that fixes branch lengths at their maximum likelihood estimates yields posterior probabilities that more closely match those that would be inferred if the true branch lengths were known in advance and reduces the rate of strongly supported false inferences compared with fully Bayesian integration.     

The effect of progesterone on the localization of progesterone receptors in the nuclei of chick oviduct cells

Summary The location of occupied and unoccupied progesterone receptors (PR) in chick oviduct cells was studied by immuno-electron microscopy with the use of a highly specific polyclonal anti-PR antibody and pre-embedding modifications of the peroxidase-anti-peroxidase-(PAP-) or immunogold-silver methods. Both methods revealed a nuclear localization of the PRs. The location of the PR in the nucleus was studied in detail by means of the immunogold-silver method. The most intense labelling for unoccupied PRs was in the condensed chromatin. After occupation of PRs with progesterone (P), decondensation or dispersion of chromatin was observed. At the same time, the labelling in the border area of condensed and dispersed chromatin, and in the dispersed chromatin, increased. The changes were statistically significant. The results can be explained by conformational changes of the PR-containing chromatin rather than by translocation of PRs from one site to another.     

Effect of the axial ligands on the structure and reactivity of tin verdoheme in the ring opening process

Conversion of tin(IV) verdoheme complex to tin(IV) biliverdin complex in the presence of hydroxide ion as a nucleophile and various axial ligands has been investigated using the B3LYP method. Our calculations show that in the six coordinate tin(IV) verdoheme complex with imidazole and hydroxyl axial ligands, conversion of tin(IV) verdoheme to open chain macrocycle is favorable thermodynamically but not kinetically. It has been determined that ring opening is prevented through a ligand-centered mechanism. Whereas, in other six coordinate complexes, formation of open chain macrocycles is favorable from both thermodynamics and kinetics point of views. On the contrary, in the five and four coordinate verdoheme complexes of tin(IV) binding of hydroxide to tin terminates the reaction at verdoheme stage and the ring opening is blocked. In fact, in the two latter coordination states, metal-centered inhibition is the proposed mechanism for blocking the ring opening. NBO analysis has shown that in the six coordinate verdoheme complexes internal hydrogen bonding has a key role in inhibition or facilitation of ring opening. These key findings have been confirmed with the results obtained from MO analysis. The presented results could be a hint for the possible implications or coordination for the competitive inhibition of degradation of verdoheme to biliverdin by hydrolysis reaction.     

The effects of posterolateral spine length and body length on feeding rate in the rotifer,Brachionus calyciflorus

The length of the posterolateral spines in the rotifer, Brachionus calyciflorus, is variable. The effect of the length of these spines on the clearance rates of B. calyciflorus was examined under laboratory conditions using radioactively-labelled yeast (Rhodotorula) and bacteria (Aerobacter). The hypothesis that individuals with longer spines have higher clearance rates than those of similarly-sized individuals with shorter spines was rejected. The effect of body length (L) on the clearance rates (C) of short-spined and long-spined animals was also examined. Statistically significant linear regressions of the form log₁₀ C = aL + b, were derived for both types. The slopes of both regressions were similar and suggest that clearance rate in B. calyciflorus increases as a cube function of body length.     

The effect of stride length on the dynamics of barefoot and shod running

A number of interventions and technique changes have been proposed to attempt to improve performance and reduce the number of running related injuries. Running shoes, barefoot running and alterations in spatio-temporal parameters (stride frequency and stride length) have been associated with significant kinematic and kinetic changes, which may have implications for performance and injury prevention. However, because footwear interventions have been shown to also affect spatio-temporal parameters, there is uncertainty regarding the origin of the kinematic and kinetic alterations. Therefore, the purpose of this study was to independently evaluate the effects of shoes and changes in stride length on lower extremity kinetics. Eleven individuals ran over-ground at stride lengths ±5 and 10% of their preferred stride length, in both the barefoot and shod condition. Three-dimensional motion capture and force plate data were captured synchronously and used to compute lower extremity joint moments. We found a significant main effect of stride length on anterior–posterior and vertical GRFs, and sagittal plane knee and ankle moments in both barefoot and shod running. When subjects ran at identical stride lengths in the barefoot and shod conditions we did not observe differences for any of the kinetic variables that were measured. These findings suggest that barefoot running triggers a decrease in stride length, which could lead to a decrease in GRFs and sagittal plane joint moments. When evaluating barefoot running as a potential option to reduce injury, it is important to consider the associated change in stride length.     

Internode length in Lathyrus odoratus. Effects of mutants l and lb on gibberellin metabolism and levels

After the application of [¹³C³H]-gibberellin A₂₀ to wild-type (tall) sweet peas ( Lathyrus odoratus L.) labelled gibberellin A₁ (GA₁), GA₈, GA₂₉ and 2-epiGA₂₉ were identified as major metabolities by gas chromatography-mass spectrometry after high performance liquid chromatography. By contrast in genetically comparable dwarf ( II ) plants only labelled GA₂₉ and 2-epiGA₂₉ were produced in significant amounts, although evidence was obtained for trace amounts of labelled GA₁ and GA₈. The apical portions of dwarf plants contained 8–10 times less GA₁ than those of tall plants but at least as much GA₂₀ (measured using di-deuterated internal standards). In conjunction with previous data these results strongly indicate that in genotype ll internode length is reduced and leaf growth altered by a reduction in GA1 levels attributable to a partial block in the 3β-hydroxylation of GA₂₀ to GA₁.
In contrast to dwarf plants, semidwarf plants (genotype lblb ) contained more GA₁ in the apical portion than wild-type counterparts. This is consistent with the suggestion that lb alters some aspect of GA sensitivity.     

Dependence of the Curative Effects of Phosphene Electrostimulation on Its Frequency in Patients with Myopia

We studied the curative effects of transcutaneous stimulation of the visual analyzer (phosphene electrical stimulation, PhES) in patients with uncomplicated myopia. PhES frequencies of 30 and 15 sec^-1 were used in groups I (45 persons) and II (64 persons), respectively. After the PhES course, means of the visual acuity increased in these groups by 12 and 69%. The reserves of accommodation for long distances and mesopic visual acuity increased in these groups by 22 and 65% and by 10 and 21%, respectively. The light sensitivity of the cone phase did not significantly change and in both groups remained within a normal range. We discuss possible mechanisms of PhES-induced changes in the visual analyzer and conclude that a certain correction of the generally used PhES frequency (its shift toward lower values) can noticeably increase the efficiency of this therapeutic technique.     

吗啡对鸡胚胎发育的影响

目的：研究吗啡对胎动、心率、孵化率、孵化时间、雏鸡体重等的影响。方法：以气室给药的方式给鸡胚注射吗啡,记录胎动、心率、孵化率、孵化时间、雏鸡体重。结果：吗啡可以缩短雏鸡的孵化时间,降低雏鸡的孵化率,并导致雏鸡出现运动障碍;20mg／kg吗啡剂量和12—16胚龄的给药时间,鸡胚孵化率最高,残疾率最低;吗啡导致胚胎心率加快,胎动减少（P〈0．05）。结论：吗啡对胚胎发育有损伤作用,损伤程度与吗啡剂量和给药时间有关。     

Effects of temperature and storage length on seed germination and the effects of light conditions on seedling establishment with respect to seed size in Ligularia virgaurea

Ligularia virgaurea is widely distributed in the alpine meadows of the eastern Qinghai-Tibet plateau. We studied the effects of temperature and seed storage length on seed germination in a laboratory experiment, the effects of seed mass and light intensity on seed emergence in a pot experiment, and the effect of meadow disturbance intensity on seed emergence in a field experiment. Our results showed that seeds of L. virgaurea germinated well under a wide range of temperatures. Germination percentage decreased with increased seed storage length. When seeds were stored for either 6 or 12 months the germination percentage increased with decreasing temperature. The emergence percentage of large seeds was higher than that of small seeds. Seedling survival of large seeds was greater than that of small seeds in 75% and 50% of natural irradiance. Large seeds of L. virgaurea were more successful colonizers in the alpine meadows. Seeds of L. virgaurea germinated in both disturbed meadows and non-disturbed meadows, but seed emergence and seedling establishment were higher in the disturbed meadows, that is, disturbance could facilitate the recruitment and establishment of L. virgaurea .