Insertion of Pro-Hyp-Gly provides 2 kcal mol-1 stability but attenuates the specific assembly of ABC heterotrimeric collagen triple helices.

Collagen is a major structural component of the extracellular matrix and connective tissue. The key structural feature of collagen is the collagen triple helix, with a Xaa-Yaa-Gly (glycine) repeating pattern. The most frequently occurring triplet is Pro (proline)-Hyp (hydroxyproline)-Gly. The reversible thermal folding and unfolding of a series of heterotrimeric collagen triple helices with varying number of Pro-Hyp-Gly triplets were monitored by circular dichroism spectroscopy to determine the unfolding thermodynamic parameters Tm (midpoint transition temperature), ΔHTm (unfolding enthalpy), and ΔGunfold (unfolding free energy). The Tm and ΔGunfold of the heterotrimeric collagen triple helices increased with increasing number of Pro-Hyp-Gly triplets. The ΔGunfold increased by 2.0 ± 0.2 kcal mol-1 upon inserting one Pro-Hyp-Gly triplet into all three chains. The Tm difference between the most stable ABC combination and the second most stable BCC combination decreased with increasing number of Pro-Hyp-Gly triplets, even though the ΔGunfold difference remained the same. These results should be useful for tuning the stability of collagen triple helical peptides for hydrogel formation, recognition of denatured collagen triple helices as diagnostics and therapeutics, and targeted drug delivery.

Longer charged amino acids favor ß-strand formation in hairpin peptides.

Interactions between charged amino acids significantly influence the structure and function of proteins. The encoded charged amino acids Asp, Glu, Arg, and Lys have different number of hydrophobic methylenes linking the backbone to the charged functionality. It remains to be fully understood how does this difference in the number of methylenes affect protein structure stability. Protein secondary structures are the fundamental three-dimensional building blocks of protein structures. ß-Sheet structures are particularly interesting, because these structures have been associated with a number of protein misfolding diseases. Herein, we report the effect of charged amino acid side chain length at two ß-strand positions individually on the stability of a ß-hairpin. The charged amino acids include side chains with a carboxylate, an ammonium, or a guanidinium group. The experimental peptides, fully folded reference peptides, and fully unfolded reference peptides were synthesized by solid phase peptide synthesis and analyzed by 2D NMR methods including TOCSY, DQF-COSY, and ROESY. Sequence specific assignments were performed for all peptides. The chemical shift data were used to derive the fraction folded population and the folding free energy for the experimental peptides. Results showed that the fraction folded population increased with increasing charged amino acid side chain length. These results should be useful for developing functional peptides that adopt the ß-conformation.

Comparison of microRNA expression in hippocampus and the marginal division (MrD) of the neostriatum in rats.

BACKGROUND: MicroRNAs (miRNAs), a class of highly conserved small non-coding RNA molecules, are known to play essential roles in central nervous system (CNS) by causing post-transcriptional gene silencing. There is much evidence that miRNAs have specific temporal and spatial expression patterns in the mammal brain, but little is known about the role of the region specificity for the gene regulatory networks of the brain. This study represents the first attempt to perform a profiling analysis of the differential expression of miRNAs between hippocampus and the Marginal division (MrD) of the neostriatum in the rat brain. RESULTS: Microarray was used to detect the expression of 357 miRNAs in hippocampus and the MrD from three rats. A short-list of the most dysregulated 30 miRNAs per rat was generated for data analysis, and the miRNAs that were represented in two or three short-lists were then further analyzed. Quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) was employed to validate the aberrantly expressed miRNAs obtained from the miRNA microarray analysis. A family of 11 miRNAs demonstrated differential expression between the MrD and hippocampus in more than one rat. Amongst these, miR-383 was differentially expressed in all three rats and up-regulated to the largest degree in rat one, and the ten other miRNAs, let-7d*, miR-181b, miR-187, miR-195, miR-214, miR-382, miR-411, miR-466b, miR-592 and miR-1224 were differentially expressed in at least two rats. Of these ten, besides miR-382 and miR-411 which were up-regulated in one rat and down-regulated in another, the other eight miRNAs retained a uniform direction of regulation (up-regulation or down-regulation) between different specimens. When further examined by RT-PCR, the aberrantly expressed miRNAs, except miR-383 and let-7d*, demonstrated differential expression that significantly correlated with the microarray findings. CONCLUSION: This study reported that the miRNA expression patterns in MrD was distinct from that of Hip, suggesting the role of miRNAs in the learning and memory function of the MrD probably different from hippocampus.

Lipopolysaccharide-induced endotoxaemia during adolescence promotes stress vulnerability in adult mice via deregulation of nuclear factor erythroid 2-related factor 2 in the medial prefrontal cortex.

RATIONALE: Sepsis is a severe inflammatory response to infection that leads to long-lasting cognitive impairment and depression after resolution. The lipopolysaccharide (LPS)-induced endotoxaemia model is a well-established model of gram-negative bacterial infection and recapitulates the clinical characteristics of sepsis. However, whether LPS-induced endotoxaemia during adolescence can modulate depressive and anxiety-like behaviours in adulthood remains unclear. OBJECTIVES: To determine whether LPS-induced endotoxaemia in adolescence can modulate the stress vulnerability to depressive and anxiety-like behaviours in adulthood and explore the underlying molecular mechanisms. METHODS: Quantitative real-time PCR was used to measure inflammatory cytokine expression in the brain. A stress vulnerability model was established by exposure to subthreshold social defeat stress (SSDS), and depressive- and anxiety-like behaviours were evaluated by the social interaction test (SIT), sucrose preference test (SPT), tail suspension test (TST), force swimming test (FST), elevated plus-maze (EPM) test, and open field test (OFT). Western blotting was used to measure Nrf2 and BDNF expression levels in the brain. RESULTS: Our results showed that inflammation occurred in the brain 24 h after the induction of LPS-induced endotoxaemia at P21 but resolved in adulthood. Furthermore, LPS-induced endotoxaemia during adolescence promoted the inflammatory response and the stress vulnerability after SSDS during adulthood. Notably, the expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and BDNF in the mPFC were decreased after SSDS exposure in mice treated with LPS during adolescence. Activation of the Nrf2-BDNF signalling pathway by sulforaphane (SFN), an Nrf2 activator, ameliorated the effect of LPS-induced endotoxaemia during adolescence on stress vulnerability after SSDS during adulthood. CONCLUSIONS: Our study identified adolescence as a critical period during which LPS-induced endotoxaemia can promote stress vulnerability during adulthood and showed that this effect is mediated by impairment of Nrf2-BDNF signalling in the mPFC.

Antifouling and antibacterial behavior of membranes containing quaternary ammonium and zwitterionic polymers.

To overcome the organic-/bio- fouling of the membrane, a dual-functional ultrafiltration membrane containing quaternary ammonium and zwitterionic polymers via quaternization and surface radical polymerization was designed, and its antifouling and antibacterial behavior was studied. In this work, poly(vinylidene fluoride)/poly(methyl methacrylate-co-dimethylamino-2-ethyl methacrylate) (PVDF/P(MMA-co-DMAEMA)) blend membrane was quaternized by p-chloromethyl styrene (p-CMS), and the double bonds were introduced onto the membrane surface, which further participated in the polymerization of zwitterionic monomers on the membrane surface. The results indicated that the resultant membrane exhibited obviously improved hydrophilicity and weak positive charge (isoelectric point, 7.49). The membrane presented higher flux recovery ratio and lower protein adhesion compared with the pure PVDF membrane. Meanwhile, the membrane showed high-efficiency broad-spectrum antibacterial performance, that is, the bacteria killing efficiency of S. aureus and E. coli reached 98.2% and 97.0%, respectively. Moreover, the membrane effectively inhibited bacterial adhesion, which is important for the long-term antibacterial properties of membrane. This antifouling and antibacterial PVDF membrane may have potential in the long-term filtration process, especially when dealing with microbiologically contaminated water.

Efficacy of the WINROP algorithm for retinopathy of prematurity screening in Southern China.

AIM: To evaluate the predicting efficacy of severe retinopathy of prematurity (ROP) by the WINROP algorithm (http://winrop.com) in Southern China. METHODS: All preterm infants with the gestational age (GA) less than 32wk were included. Their ROP screening results and serial postnatal body weight were analysed retrospectively. Weekly body weight was entered into and measured by the WINROP system. The outcomes were analysed, and the sensitivity, specificity, positive predictive value and negative predictive value (NPV) were calculated. RESULTS: Totally 432 infants with a median GA of 30.0 (24.0-31.9)wk, and a median birth weight (BW) of 1360 (540-2700) g were included. Among these 432 infants, 50 were diagnosed as type 1 ROP but only 28 were identified by the WINROP algorithm. The sensitivity was 56% (28/50) and the NPV was 92% (252/274). However, for infants with BW <1000 g or GA <28wk, the sensitivity was 93.8% (15/16) and 93.3% (14/15), respectively. Meanwhile, with several postnatal complications added as additional risk factors, the sensitivity was increased to 96% (48/50). CONCLUSION: The sensitivity of the WINROP algorithm from the Southern Chinese cohort is not as high as that reported in developed countries. This algorithm is effective for detecting severe ROP from extremely small or preterm infants. Modification of the algorithm with additional risk factors could improve the predictive value for infants with a GA>28wk in China.

New learning and memory related pathways among the hippocampus, the amygdala and the ventromedial region of the striatum in rats.

BACKGROUND: The hippocampus, central amygdaloid nucleus and the ventromedial region (marginal division) of the striatum have been reported to be involved in the mechanism of learning and memory. This study aimed elucidating anatomical and functional connections among these brain areas during learning and memory. RESULTS: In the first part of this study, the c-Fos protein was used to explore functional connections among these structures. Chemical stimulation of either hippocampus or central amygdaloid nucleus results in dense expression of c-Fos protein in nuclei of neurons in the marginal division of the striatum, indicating that the hippocampus and the central amygdaloid nucleus might be functionally connected with the marginal division. In the second part of the study, the cholera toxin subunit B-horseradish peroxidase was injected into the central amygdaloid nucleus to observe anatomical connections among them. The retrogradely transported conjugated horseradish peroxidase was observed in neurons of both the marginal division and dorsal part of the hippocampus following the injection. Hence, neural fibers from both the marginal division and the hippocampus directly projected to the central amygdaloid nucleus. CONCLUSION: The results implicated potential new functional and structural pathways through these brain areas during the process of learning and memory. The pathways ran from ventromedial portion (the marginal division) of the striatum to the central amygdaloid nucleus and then to the hippocampus before going back to the marginal division of the striatum. Two smaller circuits were between the marginal division and the central amygdaloid nucleus, and between the central amygdaloid nucleus and the hippocampus. These connections have added new dimensions of neural networks of learning and memory, and might be involved in the pathogenesis of dementia and Alzheimer disease.

The marginal division of the striatum and hippocampus has different role and mechanism in learning and memory.

The memory function of the hippocampal formation (Hip) and the marginal division (MrD) of neostriatum was compared. Rats with bilateral lesions of the MrD either immediate or 24 h after training in Y-maze were found to have decrease in correct runs in both groups. However, animals with transected afferent and efferent nerve bundles to isolate the Hip immediately or 24 h after training in Y-maze were found to show a decrease in correct runs only in the group injured immediately after Y-maze training but not in the 24 h group suggesting that MrD is likely involved in the entire process of long-term memory consolidation whereas the Hip only contributes to memory in the early stage. In addition, animals treated with a NMDA receptor (NMDAR) blocker, e.g. MK-801, showed decreased correct runs in Y-maze test and in expression level of phosphorylated CREB (pCREB) in neurons of the MrD but not in the Hip. Furthermore, animals treated with okadaic acid (OA), a potent protein phosphatase 1 inhibitor, showed increased correct runs in the Y-maze test. The expression level of pCREB and c-Fos and c-Jun was found increased in neurons of the MrD and the Hip in response to OA treatment. In conclusion, NMDAR and pCREB are involved in memory functions of both the Hip and the MrD. NMDAR might regulate pCREB level in neurons of the MrD but not in the Hip. Hence, the processes and mechanism of learning and memory involved in the MrD and the Hip may be different.

Application of Nano-Carbon in lymph node dissection and protection of parathyroid glands in 3D laparoscopic thyroidectomy / 中国内镜杂志

Objective To explore the clinical significance of Nano-Carbon particles and 3D laparoscopy in central compartment lymph node dissection and parathyroid glands protection in treatment of cN0 thyroid cancer. Methods We conduct a retrospective analysis of sixty-five patients with cN0 thyroid cancer who were received 3D laparoscopic thyroidectomy in the last 3 years. All patients were received total resection of thyroid plus the affected side and (or) contralateral side central compartment lymph node dissection. All patients were allocated to control group (n = 32) and carbon nano-particles trace group (tracer group, n = 33). The lymph node-related indexes (including number of dissected lymph node at Ⅵ area, number of Metastatic lymph node and Frozen lymph node-positive rate at Ⅵ area), serum calcium (24 h after surgery) and PTH (48 h after surgery) were collected and compared between the 2 groups. Results Number of dissected lymph node at Ⅵ area, positive rates of intraoperative frozen-section examination of parathyroid glands and PTH (48 h after surgery) were found statistical higher in nanoparticles group than control (P < 0.05). No statistical difference were found in Number of Metastatic lymph node and serum calcium (24 h after surgery) (P < 0.05). Conclusion The clinical significance of carbon nanoparticles and 3D laparoscopy is effective and feasible for central compartment lymph node dissection and parathyroid glands protection in treatment of cN0 thyroid cancer.

Application of Nano-Carbon in lymph node dissection and protection of parathyroid glands in 3D laparoscopic thyroidectomy / 中国内镜杂志

Objective To explore the clinical significance of Nano-Carbon particles and 3D laparoscopy in central compartment lymph node dissection and parathyroid glands protection in treatment of cN0 thyroid cancer. Methods We conduct a retrospective analysis of sixty-five patients with cN0 thyroid cancer who were received 3D laparoscopic thyroidectomy in the last 3 years. All patients were received total resection of thyroid plus the affected side and (or) contralateral side central compartment lymph node dissection. All patients were allocated to control group (n = 32) and carbon nano-particles trace group (tracer group, n = 33). The lymph node-related indexes (including number of dissected lymph node at Ⅵ area, number of Metastatic lymph node and Frozen lymph node-positive rate at Ⅵ area), serum calcium (24 h after surgery) and PTH (48 h after surgery) were collected and compared between the 2 groups. Results Number of dissected lymph node at Ⅵ area, positive rates of intraoperative frozen-section examination of parathyroid glands and PTH (48 h after surgery) were found statistical higher in nanoparticles group than control (P < 0.05). No statistical difference were found in Number of Metastatic lymph node and serum calcium (24 h after surgery) (P < 0.05). Conclusion The clinical significance of carbon nanoparticles and 3D laparoscopy is effective and feasible for central compartment lymph node dissection and parathyroid glands protection in treatment of cN0 thyroid cancer.

Effects of intrathecal escin and clonidine in the treatment of neuropathic pain in rats / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effects of intrathecal escin and clonidine, used alone or in combination, in the treatment of neuropathic pain in rats and the possible mechanism.</p><p><b>METHODS</b>Ninety-six male SD rats weighing 250-300 g were chronically implanted with lumbar intrathecal catheters. One week later, the left L5 and L6 spinal nerve roots were ligated to establish the model of spinal nerve ligation neuropathic pain (SNL). The rats were then randomly divided into 16 groups (n=6), including the control (saline), escin, clonidine, escin+clonidine, and the antagonist groups. Mechanical withdrawal threshold was assessed before and at 5, 10, 20, 30, 40, 50 and 60 min after intrathecal administration was evaluated. The maximal possible effect (MPE) was calculated and the effect of the treatments on the neuropathic pain. Isobolographic analysis was performed to characterize any potential interactions between the drugs.</p><p><b>RESULTS</b>MPE was significantly higher in escin group (20, 40 microg), clonidine group (2, 5, 10 microg) and escin+clonidine group [1/4, 1/2 (escin ED(50)+clonidine ED(50))] than in the saline group (P<0.05). Intrathecal escin (5-40 microg) or clonidine (1-10 microg) alone dose-dependently alleviated neuropathic pain. Isobolographic analysis suggested a synergistic effect between escin and clonidine. Intrathecal pretreatment with yohimbine (20 microg) antagonized the effects of clonidine (P<0.01) and attenuated the action of the combination treatment with escin and clonidine (P<0.05).</p><p><b>CONCLUSION</b>Intrathecal escin and clonidine alone can dose-dependently relieve neuropathic pain. Escin and clonidine produce a synergistic effect for pain relief, which may involve the actions of alpha(2) receptor and Ca(2+) channel.</p>

Comparison of target controlled propofol infusion and sevoflurane inhalational anesthesia in laparoscopic cholecystectomy / 南方医科大学学报

<p><b>OBJECTIVE</b>To compare the effects of propofol target controlled infusion (TCI) and sevoflurane inhalational anesthesia on the hemodynamics and postoperative recovery in patients undergoing laparoscopic cholecystectomy.</p><p><b>METHODS</b>Sixty ASA IorII patients scheduled for laparoscopic cholecystectomy were randomized into propofol TCI group (group P) and sevoflurane inhalational anesthesia group (group S). In group P, TCI propofol was maintained after intubation until incision closure with the target concentration at 3 microg/ml. In group S, sevoflurane (end-tidal concentration of 2%) was maintained with oxygen flow rate of 2 L/min until incision closure. Fentanyl and vecuronium were intravenously infused according to the depth of anesthesia during the operation. MAP and HR were measured before anesthesia (T(1)), immediately after intubation (T(2)), at skin incision (T(3)), 10 min after pneumoperitoneum (T(4)) and immediately after completion of the operation (T(5)) respectively. Awake time, postoperative nausea and vomiting of the patients were observed after operation.</p><p><b>RESULTS</b>There was significant difference in MAP and HR at T(4) between the two groups (P<0.05), but not at T(1), T(2), T(3) and T(5) (P>0.05). No significant difference was also found in the awake time between the two groups (P>0.05). The incidence of PONV, however, was significantly lower in group P than in group S (P<0.05).</p><p><b>CONCLUSION</b>Propofol TCI and sevoflurane inhalational anesthesia are all effective in inducing good anesthetic effect, maintaining hemodynamic stability and ensuring rapid recovery, but propofol TCI causes lower incidence of PONV in operations such as laparoscopic cholecystectomy.</p>

Acute normovolemic hemodilution combined with controlled hypotension in patients undergoing liver tumorectomy / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the effects of acute normovolemic hemodilution (ANH) combined with controlled hypotension on reducing heterogeneous transfusion and safety during liver tumorectomy.</p><p><b>METHODS</b>Thirty patients undergoing elective liver tumorectomy were randomly divided into 3 groups (10 each), namely ANH group (group A), ANH combined with controlled hypotension group (group B) and control group (group C). All the patients were anesthetized via endotracheal intubation. Before the operation, ANH was performed in groups A and B after anesthesia induction, and controlled hypotension was initiated in group B during tumorectomy. Blood transfusion and fluid infusion were carried out routinely in group C. Hb and Hct were measured before operation, after ANH, and immediately, 1 day and 7 days after the operation. The difference in intraoperative blood loss and heterogeneous blood transfusion volume in the 3 groups was observed.</p><p><b>RESULTS</b>In group A, heterogeneous blood transfusion was avoided in 6 cases and but given in the other cases for an average of 400 ml. In group C, every patient received heterogeneous blood transfusion (664.8-/+248.1 ml), but none of the patients received heterogeneous blood in group B. The difference in transfusion volume between the 3 groups was significant (P<0.01). Hemodynamics was basically stable during operation in the 3 groups.</p><p><b>CONCLUSION</b>ANH combined with controlled hypotension is safe and effective for decreasing and even avoiding homologous blood transfusion in liver tumorectomy.</p>