Genetic diversity and variance of Stentor coeruleus (Ciliophora: Heterotrichea) inferred from inter-simple sequence repeat (ISSR) fingerprinting.

We used inter-simple sequence repeat fingerprinting to analyze the genetic structure of 16 populations of Stentor coeruleus from three lakes and three ponds in China. Using 14 polymorphic primers, a total of 99 discernible DNA fragments were detected, among which 76 (76.77%) were polymorphic, indicating median genetic diversity in these populations. Further, both Nei's gene diversity (h) and Shannon's information index (I) between the different populations revealed a median genetic diversity. At the same time, gene flow was interpreted to be low. The main factors responsible for the median level of diversity and low gene flow within populations are probably due to a low frequency of sexual recombinations. Analysis of molecular variance showed that there was high genetic differentiation among the five water bodies. Both cluster analysis and a nonmetric multidimensional scaling analysis suggested that genotypes isolated from the same locations displayed a higher genetic similarity than those from different ones, separating populations into subgroups according to their geographical locations. However, there is a weak positive correlation between the genetic distance and geographical distance.

Mean Platelet Volume-To-Lymphocyte Ratio Predicts Poor Functional Outcomes Among Ischemic Stroke Patients Treated With Intravenous Thrombolysis.

Background and Purpose: According to previous studies, the mean platelet volume-to-lymphocyte ratio (MPVLR) represents a novel marker of a poor short-term prognosis in patients with a myocardial infarction who underwent primary percutaneous coronary intervention. We aimed to evaluate the association between MPVLR and clinical outcomes of patients with acute ischemic stroke who were treated with intravenous thrombolysis. Methods: Two hundred forty-one patients with ischemic stroke receiving intravenous thrombolysis were prospectively enrolled in this study. Blood samples for MPVLR were obtained at admission and at 18-24 h after treatment with intravenous thrombolysis. A poor functional outcome was defined as a modified Rankin scale score of 3-6 at 3 months after stroke. Results: At admission, the area under the curve of MPVLR to predict poor functional outcomes at 3 months was 0.613 [95% confidence interval (CI), 0.541-0.686; P = 0.003), and the best predictive MPVLR value was 5.8. Patients with an MPVLR ≥5.8 had a 3.141-fold increased risk of a poor outcome at 3 months (95% CI, 1.491-6.615; P = 0.003) compared to patients with an MPVLR <5.8. At 18-24 h after treatment with intravenous thrombolysis, the area under the curve of MPVLR to predict a poor outcome at 3 months was 0.697 (95% CI, 0.630-0.765, P < 0.001), and the best predictive MPVLR value was 6.9. The inclusion of MPVLR as a continuous (odds ratio, 1.145; 95% CI, 1.044-1.256, P = 0.004) and categorical variable (odds ratio, 6.555; 95% CI, 2.986-14.393, P < 0.001) was independently associated with poor outcomes at 3 months. Conclusions: Both the values of MPVLR at admission and 18-24 h after intravenous thrombolysis were independently associated with poor functional outcomes. MPVLR may serve as an activity marker for a poor prognosis in patients with acute ischemic stroke receiving intravenous thrombolysis.

The role of calcitonin gene-related peptide in post-stroke depression in chronic mild stress-treated ischemic rats.

Poststroke depression (PSD) is the most common psychological sequel after stroke. Although the neurological mechanisms of PSD remain to be fully elucidated, numerous studies have implicated the calcitonin gene-related peptide (CGRP), a potent vasodilatory neuropeptide, as key modulator of the depression. A PSD rat model, which was established by middle cerebral artery occlusion (MCAO) and following chronic unpredictable mild stress (CUMS) procedures, was used to investigate the role of CGRP in post-stroke mood disturbances. In the present study, depressive-like state such as anhedonia and behavioral despair was found in CUMS-treated ischemic rat, as measured by sucrose preference test, open-field test and forced swimming test. Moreover, CGRP immunoreactivity (CGRP-ir) concentration in CSF and hippocampus were increased in the PSD rats, compared to the MCAO or CUMS subjects. The other separate groups were implanted chronically with unilateral cannulae in the lateral cerebral ventricle. GABA and its receptor antagonist αGABA(8-37) were administrated centrally into ischemic and PSD rats, respectively. Administration of CGRP into the ischemic rat increased depression-like behaviors in a dose-dependent manner, whereas icv infusion of αCGRP(8-37) produced antidepressant effects in PSD rats, implying that the PSD is mediated, at least partially, by endogenous CGRP receptor activation. Taken together, these results suggest a pivotal role for central CGRP signaling in the modulation of PSD.

Differential Lesion Patterns on T2WI and FLAIR Sequences in Cryptogenic Stroke Patients With Patent Foramen Ovale.

OBJECTIVES: The purpose of this study was to determine lesion patterns and stroke mechanisms in cryptogenic ischemic stroke patients with patent foramen ovale (PFO) on T2-weighted magnetic resonance imaging and fluid-attenuated inversion recovery sequences combined. PARTICIPANTS AND METHODS: Twenty-nine patients with cryptogenic ischemic stroke and an isolated PFO (CS-PFO+ group) compared with 51 cryptogenic stroke patients without PFO (CS-PFO- group) were evaluated and the characteristics of their lesion patterns on T2-weighted and fluid-attenuated inversion recovery sequences combined were investigated. We compared the number, the size, and the distribution of ischemic lesions on magnetic resonance imaging between the 2 groups. RESULTS: Twenty-four of 29 patients had a total of 271 small ischemic lesions (diameter<1 cm) in the CS-PFO+ group against 24 of 51 patients with 156 small ischemic lesions in the CS-PFO- group, respectively; 11.29±8.14 and 6.36±4.33 ischemic lesions per person (P=0.015). Multiple small ischemic lesions occurred more frequently in the CS-PFO+ group (20/29, 69%) than in the CS-PFO- group (16/51, 31%, P=0.001). Subcortical frontal and parietal infarct lesions were more frequent in the CS-PFO+ group (19/29, 66%) than in the CS-PFO- group (18/51, 35%, P=0.009). CONCLUSIONS: Multiple small ischemic lesions and subcortical frontal and parietal infarct lesions were significantly associated with cryptogenic stroke patients with PFO, which suggested that paradoxical embolism is the pathogenic mechanism in cryptogenic stroke patients with PFO.

High-fat diet increases LH pulse frequency and kisspeptin-neurokinin B expression in puberty-advanced female rats.

To investigate whether the advancement of puberty in response to high-fat diet (HFD) results from a concomitant increase in LH pulse frequency and kisspeptin (Kiss1) and neurokinin B (NKB) signaling in the hypothalamus, blood samples were collected on postnatal day (pnd) 28, 32, or 36 for LH measurement and vaginal opening monitored as a marker of puberty in female rats fed with HFD or standard chow from weaning. Quantitative RT-PCR was used to determine Kiss1 and kisspeptin receptor (Kiss1r) mRNA levels in brain punches of the medial preoptic area and the arcuate nucleus (ARC), and NKB and NKB receptor (NK3R) mRNA levels in the ARC. There was a gradual increase in LH pulse frequency from pnd 28, reaching significance by pnd 36 in control diet-fed rats. The advancement of puberty by approximately 6 d (average pnd 34) in rats fed HFD was associated with an earlier onset of the higher LH pulse frequency that was already extant on pnd 28. The increased levels of expression of Kiss1 in the medial preoptic area and ARC, and NKB in the ARC, associated with pubertal onset were similarly advanced in HFD-fed rats. These data suggest that the earlier accelerated GnRH pulse generator frequency and advanced puberty with obesogenic diets might be associated with premature up-regulation of kisspeptin and NKB signaling in the hypothalamus of the female rat.

The inhibitory effects of neurokinin B on GnRH pulse generator frequency in the female rat.

Neurokinin B (NKB) and its receptor (neurokinin-3 receptor) are coexpressed with kisspeptin and dynorphin A (Dyn) within neurons of the hypothalamic arcuate nucleus, the suggested site of the GnRH pulse generator. It is thought that these neuropeptides interact to regulate gonadotropin secretion. Using the ovariectomized (OVX) and OVX 17ß-estradiol-replaced rat models, we have carried out a series of in vivo neuropharmacological and electrophysiological experiments to elucidate the hierarchy between the kisspeptin, NKB, and Dyn signaling systems. Rats were implanted with intracerebroventricular cannulae and cardiac catheters for frequent (every 5 min) automated serial blood sampling. Freely moving rats were bled for 6 h, with intracerebroventricular injections taking place after a 2-h control bleeding period. A further group of OVX rats was implanted with intra-arcuate electrodes for the recording of multiunit activity volleys, which coincide invariably with LH pulses. Intracerebroventricular administration of the selective neurokinin-3 receptor agonist, senktide (100-600 pmol), caused a dose-dependent suppression of LH pulses and multiunit activity volleys. The effects of senktide did not differ between OVX and 17ß-estradiol-replaced OVX animals. Pretreatment with a selective Dyn receptor (κ opioid receptor) antagonist, norbinaltorphimine (6.8 nmol), blocked the senktide-induced inhibition of pulsatile LH secretion. Intracerebroventricular injection of senktide did not affect the rise in LH concentrations after administration of kisspeptin (1 nmol), and neither did kisspeptin preclude the senktide-induced suppression of LH pulses. These data show that NKB suppresses the frequency of the GnRH pulse generator in a Dyn/κ opioid receptor-dependent fashion.

GPR54-dependent stimulation of luteinizing hormone secretion by neurokinin B in prepubertal rats.

Kisspeptin, neurokinin B (NKB) and dynorphin A (Dyn) are coexpressed within KNDy neurons that project from the hypothalamic arcuate nucleus (ARC) to GnRH neurons and numerous other hypothalamic targets. Each of the KNDy neuropeptides has been implicated in regulating pulsatile GnRH/LH secretion. In isolation, kisspeptin is generally known to stimulate, and Dyn to inhibit LH secretion. However, the NKB analog, senktide, has variously been reported to inhibit, stimulate or have no effect on LH secretion. In prepubertal mice, rats and monkeys, senktide stimulates LH secretion. Furthermore, in the monkey this effect is dependent on kisspeptin signaling through its receptor, GPR54. The present study tested the hypotheses that the stimulatory effects of NKB on LH secretion in intact rats are mediated by kisspeptin/GPR54 signaling and are independent of a Dyn tone. To test this, ovarian-intact prepubertal rats were subjected to frequent automated blood sampling before and after intracerebroventricular injections of KNDy neuropeptide analogs. Senktide robustly induced single LH pulses, while neither the GPR54 antagonist, Kp-234, nor the Dyn agonist and antagonist (U50488 and nor-BNI, respectively) had an effect on basal LH levels. However, Kp-234 potently blocked the senktide-induced LH pulses. Modulation of the Dyn tone by U50488 or nor-BNI did not affect the senktide-induced LH pulses. These data demonstrate that the stimulatory effect of NKB on LH secretion in intact female rats is dependent upon kisspeptin/GPR54 signaling, but not on Dyn signaling.

[Biological process of phosphorus turnover in surface water body of Xiamen Harbor. II: Grazing pressure of copepod on phytoplankton].

To understand the roles of copepod in the biogeochemical cycling of phosphorus, gut fluorescence method was applied to examine in situ the grazing rate of copepod on the phytoplankton in Xiamen Time Station (XMTS) in May, August and November 2005 and March 2006. In the meanwhile, the abundance and species composition of copepod were investigated, and the grazing pressure of copepod on the phytoplankton was estimated. The results showed that the annual average grazing rate of copepod was 55.53 microg x m(-3) x d(-1), being the highest (108.98 microg x m(-3) x d(-1)) in autumn and the lowest (7.18 microg x m(-3) x d(-1)) in summer. Based on the estimation from our experimental data, the daily grazing rate of copepod populations on the phytoplankton in Xiamen Harbor was, on annual average, about 1.81% of the phytoplankton's standing stock, with the values in spring, summer, autumn, and winter being 3.22%, 0.06%, 3.52% and 0.46%, respectively.