Publications by authors named "Liang Z Yan"

Objective: To analyze differences in feasibility and efficacy between the paravertebral approach and microtubular tumorectomy (PAMT) or percutaneous transforaminal endoscopic tumorectomy (PTET) for the treatment of lumbar dumbbell-shaped tumors.

Methods: Clinical data of dumbbell-shaped lumbar tumors in patients treated with PAMT or PTET in our hospital between June 2015 and November 2020 were retrospectively analyzed. The gross total resection (GTR) rate, operation time, estimated blood loss, postoperative hospital stay (PHS), postoperative neurological function, and spinal stability were compared between the 2 surgical methods.

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Objective: To investigate the feasibility and efficacy of percutaneous transforaminal endoscopic discectomy (PTED) with three-step maneuver for puncture (TSMP) for lumbar herniated disc (LDH).

Methods: We performed a retrospective review of 30 patients who underwent PTED using TSMP for LDH and met inclusion criteria from January 2018 to September 2018. The primary outcome, leg or back pain, was assessed using Visual Analogue Scale (VAS).

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Introduction: To improve the efficacy of anterior cervical decompression and fusion (ACDF) and reduce postoperative complications in degenerative cervical myelopathy, our team established a set of perioperative care of enhanced recovery guidelines of ACDF based on the concept of enhanced recovery after surgery. In addition, a prospective, multicentre, randomised clinical trial was designed.

Methods And Analysis: A total of 260 patients aged 18-65 years will be included.

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Introduction: For sciatica caused by lumbar disc herniation (LDH), the standard surgical technique is conventional microdiscectomy. In recent years, minimally invasive techniques (eg, percutaneous transforaminal endoscopic discectomy (PTED), paraspinal minitubular microdiscectomy (PMTM)) have gained increasing interest. PTED and PMTM are considered alternative minimally invasive techniques for the treatment of LDH.

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The objective of this study is to investigate the effects of full airway drainage by fiber bronchoscopy through artificial airway in the treatment of traumatic atelectasis with occult manifestations. From May 2006 to May 2011, 40 cases of occult traumatic atelectasis were enrolled into our prospective study. Group A (n = 18) received drainage by nasal bronchoscope; group B underwent airway drainage by fiber bronchoscopy through artificial airway (n = 22).

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Emerging evidence demonstrates that stromal cell-derived factor 1 (SDF-1) and CXCR4, a chemokine and chemokine receptor pair, play important roles in tumorigenesis. In this report, we describe a small cyclic peptide, LY2510924, which is a potent and selective CXCR4 antagonist currently in phase II clinical studies for cancer. LY2510924 specifically blocked SDF-1 binding to CXCR4 with IC50 value of 0.

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Calcitonin gene-related peptide (CGRP), a potent dilator of cerebral and dural vasculature, is known to be elevated in plasma and cerebral spinal fluid during migraine attacks. Selective blockade of the CGRP receptor offers the promise of controlling migraine headache more effectively and without the side-effects associated with the use of triptans. Our efforts to develop a novel, peptide-based CGRP antagonist focused on the C-terminal portion of the peptide which is known to bind the receptor but lack agonist properties.

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The CXCR4/stromal cell-derived factor-1 (SDF-1) axis plays important roles in development, leukocyte trafficking, HIV infection, and tumorigenesis. Its critical function in bone marrow stem cell and hematopoietic progenitor cell retention, homing and release has been well-characterized by genetic and pharmacological analyses. However, its role in neutrophil retention and release is still poorly understood.

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The melanocortin family of receptors (MC 1-5R) and their endogenous peptide ligands (alpha, beta, gamma- MSH and ACTH) have been implicated in the control of a wide variety of behavioral and physiological functions including the homeostatic control of food intake and body weight. In rodent models, melanocortin agonists including the nonselective peptide MTII have been shown to decrease food intake and body weight while antagonists such as SHU9119 and AGRP have been shown to stimulate food intake and increase body weight. Deletion of either the MC3R or MC4R in mice was found to be associated with obesity although hyperphagia was only observed in the MC4R deficient mice.

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The recent emergence of obesity as a major health threat in the industrialized world has intensified the search for novel and effective pharmacologic treatment. The proopiomelanocortin (POMC)-melanocortin 4 receptor (MC4R) axis has been shown to regulate food intake and energy homeostasis and is considered among the most promising antiobesity targets. Our initial efforts in this area have focused on affinity and selectivity directed optimization of the native beta-MSH(5-22) sequence and resulted in the discovery of a potent MC4R agonist: Ac-Tyr-Arg-[Cys-Glu-His-D-Phe-Arg-Trp-Cys]-NH(2) (10).

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alphaMSH has generally been accepted as the endogenous ligand for melanocortin 4 receptor (MC4R), which plays a major role in energy homeostasis. Targeting MC4R to develop antiobesity agents, many investigators have performed a structure-activity relationship (SAR) studies based on alphaMSH structure. In this report, we performed a SAR study using human betaMSH (5 - 22) (DEGPYRMEHFRWGSPPKD, peptide 1) as a lead sequence to develop potent and selective agonists for MC4R and MC3R.

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Extensive structure-activity relationship studies utilizing a beta-MSH-derived cyclic nonapeptide, Ac-Tyr-Arg-[Cys-Glu-His-D-Phe-Arg-Trp-Cys]-NH(2) (3), led to identification of a series of novel MC-4R selective disulfide-constrained hexapeptide analogs including Ac-[hCys-His-D-Phe-Arg-Trp-Cys]-NH(2) (12). The structural modifications associated with profound influence on MC-4R potency and selectivity were ring size, ring conformation, and the aromatic substitution of the D-Phe7. These cyclic peptide analogs provide novel and enhanced reagents for use in the elucidation of melanocortin-4 receptor-related physiology, and may additionally find application in the treatment of obesity and related metabolic disorders.

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Human beta-MSH(1-22) was first isolated from human pituitary as a 22-amino acid (aa) peptide derived from a precursor protein, pro-opiomelanocortin (POMC). However, Bertagna et al. demonstrated that a shorter human beta-MSH(5-22), (DEGPYRMEHFRWGSPPKD), is a true endogenous peptide produced in human hypothalamus.

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A series of novel, disulfide-constrained human beta-melanocyte stimulating hormone (beta-MSH)-derived peptides were optimized for in vitro melanocortin-4 receptor (MC-4R) binding affinity, agonist efficacy, and selectivity. The most promising of these, analogue 18, was further studied in vivo using chronic rat food intake and body weight models.

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Extensive two-dimensional NMR analysis was employed to characterize the structural identity of the macrocyclic peptide lactam and the imide analog, a major side reaction product when allyl ester was used to protect the side chain of aspartic acid. A straightforward protocol modification was developed to minimize aspartimide formation during the synthesis of cyclic peptides.

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A solid-phase method for the preparation of C-terminal amino-alcohol-containing peptides using activated Wang resin is presented. A diverse set of (fluorenylmethoxy)carbonyl (Fmoc) protected amino alcohols was found to load rapidly and efficiently. The synthetic utility of this approach was demonstrated through the direct synthesis of the peptide drug octreotide with excellent yield and purity.

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