Overexpression, purification, and pharmacologic evaluation of anticancer activity of ribosomal protein L24 from the giant panda (Ailuropoda melanoleuca)

The ribosomal protein L24 (RPL24) belongs to the L24E family of ribosomal proteins and is located in the cytoplasm. The purpose of this study was to investigate the structure and anti-cancer function of RPL24 of the giant panda (Ailuropoda melanoleuca). The complementary DNA of RPL24 was cloned successfully using reverse transcription-polymerase chain reaction technology. We constructed a recombinant expression vector containing RPL24 complementary DNA and overexpressed it in Escherichia coli using pET28a plasmids. The expression product obtained was purified using Ni-chelating affinity chromatography. The results indicated that the length of the fragment cloned is 509 bp, and it contains an open-reading frame of 474 bp encoding 157 amino acids. Primary structure analysis revealed that the molecular weight of the putative RPL24 protein is 17.78 kDa with a theoretical isoelectric point of 11.86. The RPL24 gene is readily expressed in E. coli, and the RPL24 fused with the N-terminal histidine-tagged protein to give rise to the accumulation of an expected 23.51-kDa polypeptide. The inhibitory rate in mice treated with 0.1 mg/mL RPL24, the highest of 3 doses administered, can reach 67.662%, which may be comparable to the response to mannatide. The histology of organs with tumors showed that the tissues in the RPL24 group displayed a looser arrangement compared with that in the control group. Furthermore, no obvious damage was apparent in other organs, such as heart, lung, and kidney. The data showed that the recombinant RPL24 had time and dose dependency on the cell growth inhibition rate. Human laryngeal carcinoma Hep-2 cells treated with 0.3125-10 µg/mL RPL24 for 24 h displayed significant cell growth inhibition (P < 0.05; N = 6) in assays using 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide compared with that in control (untreated) cells. By contrast, human hepatoma Hep G-2 cells displayed no significant change (P > 0.05; N = 6) from control (untreated) cells. RPL24 has time and dose dependency on Hep-2 cell growth inhibition. The data indicate that the effect at low concentrations is better than that at high concentrations, and the concentration of 0.625 µg/mL provides the best rate of growth inhibition. Further research is ongoing to determine the bioactive principles of recombinant RPL24 protein that are responsible for its anticancer activity.

Developmental hypothyroxinaemia induced by maternal mild iodine deficiency delays hippocampal axonal growth in the rat offspring

Iodine is essential for the biosynthesis of thyroid hormones, including triiodothyronine and thyroxine. Thyroid hormones are important for central nervous system development. Mild maternal iodine deficiency (ID)-induced hypothyroxinaemia causes neurological deficits and mental retardation of the foetus. However, the detailed mechanism underlying these deficits is still largely unknown. Given that the growth-associated protein of 43 kDa (GAP-43), semaphorin 3A (Sema3A) and the glycogen synthase kinase 3β (GSK3β)/collapsin response mediator protein 2 (CRMP2) pathway are essential for axonal development, we hypothesise that hippocampal axonal growth-related proteins may be impaired, which may contribute to hippocampal axonal growth delay in rat offspring exposed to maternal hypothyroxinaemia. To test this hypothesis, maternal hypothyroxinaemia models were established in Wistar rats using a mild ID diet. Besides a negative control group, two maternal hypothyroidism models were created with either a severe ID diet or methimazole in the water. Our results showed that maternal hypothyroxinaemia exposure delayed offspring axonal growth on gestational day 19, postnatal day (PN) 7, PN14 and PN21. Consistent with this, the mean intensity of hippocampal CRMP2 and Tau1 immunofluorescence axonal protein was reduced in the mild ID group. Moreover, maternal hypothyroxinaemia disrupted expressions of GAP-43 and Sema3A. Furthermore, the phosphorylation of GSK3β and CRMP2 was also affected in the treated offspring, implying a potential mechanism by which hypothyroxinaemia-exposure affects neurodevelopment. Taken together, our data support the hypothesis that maternal hypothyroxinaemia may impair axonal growth of the offspring.

Effects of Rhynchophylline on relaxation and contraction of the bladder detrusor in rats

AIM

The aim of this study was to observe the effects of Rhynchophylline (Rhy) on the relaxation and contraction of rat bladder detrusor and urodynamics and determine the changes in the tension of isolated rat bladder muscle strips.

MATERIALS AND METHODS

Rats were randomly divided into four groups: sham-operated, overactive bladder (OAB) model, Rhy-treated, and the control group. Sections of urodynamic testing and electrophysiological OAB indicators of detrusor were measured. The effect of tension on the isolated rat bladder detrusor muscle strips was determined; activators and antagonists of calcium-activated potassium ion channels were detected in vitro using the tension method. The contraction of detrusor muscle strips and the antagonism of acetylcholine due to changes in muscle contraction were observed.

RESULTS

The Rhy-treated group significantly decreased the maximum bladder capacity, bladder filling pressure, leak point pressure, contraction frequency, motility index (p < 0.05). The affinity index of Rhy was 4.53 ± 0.22. However, 1 µmol/L to 2 μmol/L Rhy shifts CaCl2 cumulative dose-response curves to the right in a non-parallel manner, showing a non-competitive antagonism. Rhy inhibits detrusor contraction by blocking L-type calcium channels and activating big-conductance calcium-activated potassium channels. A low concentration of Rhy can inhibit muscle contraction caused by intracellular calcium.

CONCLUSIONS

Rhy plays an important role in OAB treatment and decreases effectively on sections of urodynamic testing and electrophysiological OAB indicators of detrusor.

Investigating hydrophobic ligand-receptor interactions in parathyroid hormone receptor using peptide probes

With an increasing number of new chemical entities entering clinical studies, and an increasing share of the market, peptides and peptidomimetics constitute one of the most promising classes of therapeutics. The success of synthetic peptides as therapeutics relies on the lead optimization step in which the lead candidates are modified to improve drug-like properties of peptides related to potency, pharmacokinetics, solubility, and stability, among others. Peptidomimetics based on the N-terminal stretch of the first 11 amino acids of the PTH have been investigated as potential lead compounds for the treatment of osteoporosis. On the basis of a peptide reported in the literature, referred to here as the Parent Peptide (H-Aib-Val-Aib-Glu-Ile-Gln-Leu-Nle-His-Gln-Har-NH2), we conducted systematic SAR analyses to investigate the effects of altering peptide hydrophobicity on PTH receptor functional potency as measured by the cAMP (cyclic adenosine monophosphate) accumulation and β-arrestin recruitment assays. Among hydrophobic residues, we found that the Val2 position shows the least flexibility in terms of the SAR studies, whereas the Leu7 position appeared to be most flexible. Through circular dichroism and nuclear magnetic resonance spectroscopy studies, we were able to establish that changes in hydrophobic residues significantly change the extent of peptide helicity and that the helical character correlates well with receptor agonist activity. Here, we report several novel PTH 1-11 peptidomimetics that show comparable or enhanced potency to stimulate Gs-signaling over β-arrestin recruitment as compared with such properties of PTH 1-34 and the Parent Peptide.

ER stress signalling through eIF2α and CHOP, but not IRE1α, attenuates adipogenesis in mice

AIMS/HYPOTHESIS

Although obesity is associated with endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR) in adipose tissue, it is not known how UPR signalling affects adipogenesis. To test whether signalling through protein kinase RNA-like ER kinase/eukaryotic initiation factor 2 alpha (PERK/eIF2α) or inositol-requiring enzyme 1 alpha/X-box binding protein 1 (IRE1α/XBP1) is required for adipogenesis, we studied the role of UPR signalling in adipocyte differentiation in vitro and in vivo in mice.

METHODS

The role of UPR signalling in adipogenesis was investigated using 3T3-L1 cells and primary mouse embryonic fibroblasts (MEFs) by activation or inhibition of PERK-mediated phosphorylation of the eIF2α- and IRE1α-mediated splicing of Xbp1 mRNA. Body weight change, fat mass composition and adipocyte number and size were measured in wild-type and genetically engineered mice fed a control or high-fat diet (HFD).

RESULTS

ER stress repressed adipocyte differentiation in 3T3-L1 cells. Impaired eIF2α phosphorylation enhanced adipocyte differentiation in MEFs, as well as in mice. In contrast, increased eIF2α phosphorylation reduced adipocyte differentiation in 3T3-L1 cells. Forced production of CCAAT/enhancer binding protein (C/EBP) homologous protein (CHOP), a downstream target of eIF2α phosphorylation, inhibited adipogenesis in 3T3-L1 cells. Mice with deletion of Chop (also known as Ddit3) (Chop (-/-)) gained more fat mass than wild-type mice on HFD. In addition, Chop deletion in genetically obese Lepr (db/db) mice increased body fat mass without altering adipocyte size. In contrast to the eIF2α-CHOP pathway, activation or deletion of Ire1a (also known as Ern1) did not alter adipocyte differentiation in 3T3-L1 cells.

CONCLUSIONS/INTERPRETATION

These results demonstrate that eIF2α-CHOP suppresses adipogenesis and limits expansion of fat mass in vivo in mice, rendering this pathway a potential therapeutic target.

A platform to parallelize planar surfaces and control their spatial separation with nanometer resolution

Parallelizing planar surfaces and manipulating them into close proximity with spatial separation of nanoscale dimensions is critical for probing phenomena such as near-field radiative heat transport and Casimir forces. Here, we report on a novel platform, with an integrated reflected light microscope, that is capable of parallelizing two planar surfaces such that the angular deviation is <6 μrad, while simultaneously allowing control of the gap from 15 μm down to contact with ∼0.15 nm resolution. The capabilities of this platform were verified by using two custom-fabricated micro-devices with planar surfaces, 60 × 60 μm(2) each, whose flatness and surface roughness were experimentally quantified. We first parallelized the two micro-devices by using the developed platform in conjunction with a simple optical approach that relies on the shallow depth of field (∼2 μm) of a long working distance microscope objective. Subsequently, we experimentally tested the parallelism achieved via the optical alignment procedure by taking advantage of electrodes integrated into the micro-devices. Our measurements unambiguously show that the simple depth-of-field based optical approach enables parallelization such that the angular deviation between the two surfaces is within ∼500 μrad. This ensures that the separation between any two corresponding points on the parallel surfaces deviate by ∼30 nm or less from the expected value. Further, we show that improved parallelization can be achieved using the integrated micro-electrodes which enable surface roughness limited parallelization with deviations of ∼5 nm from parallelism.

Gate dependent photo-responses of carbon nanotube field effect phototransistors

Gate dependent photoconductivity of carbon nanotube (CNT) field effect phototransistors (FEPs) was systematically investigated in this study. The photo-response comparisons of CNT FEPs with symmetric and asymmetric metal structures connecting to the same CNT revealed that the gate effect contributed to a sensitivity improvement with a lower dark current, a higher photocurrent, and an enhanced photovoltage. A functionalized asymmetric FEP, fabricated by partially doping the CNT utilizing a polyethylene imine (PEI) polymer, verified that FEPs delivered a better performance by using asymmetric structures. A multi-gate FEP, with three pairs of side-gates that can electrostatically dope different sections of a CNT independently, was fabricated to examine the gate structure dependent photo-responses. Experimental measurements showed an unconventional photocurrent improvement that was weakly dependent on the gate location, which was attributed to the unique charge distribution of one-dimensional semiconductors.

Possible function of the frenulum of prepuce in penile erection

Fremulum of prepuce was the ruffle of foreskin while there was little about the function of fremulum. This study discusses the possible function of the frenulum of prepuce in penile erection. Twelve patients had premature ejaculation (PE) whose frenula were short. Two patients suffered unsatisfied intercourse whose frenula were damaged and departed 12 or 6 months earlier. We prolonged the short frenulum and reconstructed the ruptured frenulum. All patients reported satisfied sexual intercourse after 3-6 months. It is concluded that the frenulum is important in penile erection. PE might be treated by lengthening the frenulum.

Effect of exogenous l-arginine and ageing on NO and ET-1 in penile tissue of rat

The aim of this study was to investigate the effect and significance of l-arginine and ageing on nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway and ET-1 in penile tissue of rats. The different months old rats were divided into control group and experiment group randomly, the content of NO, cGMP, the changes of activity of Nitrous Oxide Systems (NOS) and the content of endothelin-1(ET-1) in penile tissue were determined. Along with ageing, NO and the activity of NOS in penile tissue increased at first and then decreased (P < 0.001). The content of cGMP reduced obviously (P < 0.001), the content of ET-1 had a tendency to increase, and the ratio of ET-1/NO increased significantly (P < 0.001 or P < 0.01). After feeding rats with l-arginine for some time, both the activity of NOS and the content of cGMP increased significantly in penile tissue (P < 0.001), while there was no obvious change in the content of ET-1. Our study shows that whether the smooth muscle cells relax or contract might be decided by the content of cGMP and value of ET-1/NO in penile tissue. l-arginine had significant effect on increasing the activity of NOS and the content of NO and cGMP, indicating that l-arginine has potential clinical value to be used in treating ED.

Cathepsin L is associated with proliferation and clinical outcome of urothelial carcinoma of the bladder

Increasing evidence suggests that the activity of cysteine proteases, including cathepsin L, is important in cancer cell invasion and metastasis. This study was designed to investigate the clinicopathological and prognostic significance of cathepsin L in human urothelial carcinoma of the bladder (UCB). Standard immunohistochemistry was used to determine the presence of cathepsin L and Ki-67 (a marker of proliferation) in paraffin-embedded specimens of 82 human UCB cases. Cathepsin L protein was localized in the cytoplasm of the malignant UCB cells, and was significantly associated with the pathological tumour stage (invasiveness), tumour grade, survival, local tumour recurrence during follow-up, the occurrence of distant metastasis during follow-up and the presence of Ki-67 protein. Multivariate analysis using the Cox proportional hazards model revealed that cathepsin L immunopositivity and pathological tumour stage (invasiveness) were independent significant prognostic factors for overall survival. This study showed that cathepsin L provides significant prognostic information and that it might be a useful therapeutic target in the future.

Dynamics of population communities with prey migrations and Allee effects: a bifurcation approach

The population dynamics of predator-prey systems in the presence of patch-specific predators are explored in a setting where the prey population has access to both habitats. The emphasis is in situations where patch-prey abundance drives prey dispersal between patches, with the fragile prey populations, i.e. populations subject to the Allee effect. The resulting 3D and 4D non-linear systems depending on some parameters, which reflect 'measures' of factors under consideration, support rich dynamics and in particular a diverse number of predator-prey life history outcomes. The model's mathematical analysis is carried out via submodels that focus in lower-dimensional settings. The outcomes depend on and, in fact, are quite sensitive to the structure of the system, the range of parameter values and initial conditions. We show that the system can support multistability and a diverse set of predator-prey life-history dynamics that include rather complex dynamical system outcomes. It is argued that, in general, evolution should favour heterogeneous settings including Allee effects, prey refuges and patch-specific predators.

High strain rate testing of bovine trabecular bone

In spinal vertebral burst fractures, the dynamic properties of the trabecular centrum, which is the central region of porous bone inside the vertebra, can play an important role in determining the failure mode. If the failure occurs in the posterior portion of the vertebral body, spinal canal occlusion can occur and ejected trabecular bone can impact the spinal cord resulting in serious injury. About 15% of all spinal cord injuries are caused by such burst fractures. Unfortunately, due to the uniqueness of burst fracture injuries, postinjury investigation cannot always accurately assess the degree of damage caused by these fractures. This research makes an effort to begin understanding the governing effects in this important bone fracture event. Measurements of the dynamic deformation response of bovine trabecular bone with the marrow intact and marrow removed using a modified split-Hopkinson pressure bar apparatus are reported and compared with quasistatic deformation response results. Because trabecular bone is more compliant and lower in strength than cortical bone, typical Hopkinson pressure bar experimental techniques used for high strain rate testing of harder materials cannot be applied. Instead, a quartz-crystal-embedded, split-Hopkinson pressure bar developed for testing compliant, low strength materials is used. Care is taken into account for the orthotropic properties in the bone by testing only along the principle material axes, determined through microcomputed tomography. In addition, shaping of the stress wave pulse is used to ensure a constant strain rate and homogeneous specimen deformation. Results indicate that the strength of trabecular bone increases by a factor of approximately 2-3 when the strain rate increases from 10(-3) s(-1) to 500 s(-1) and that the bone fractures beyond a critical strain.

The unfolded protein response is required to maintain the integrity of the endoplasmic reticulum, prevent oxidative stress and preserve differentiation in β-cells

Diabetes is an epidemic of worldwide proportions caused by β-cell failure. Nutrient fluctuations and insulin resistance drive β-cells to synthesize insulin beyond their capacity for protein folding and secretion and thereby activate the unfolded protein response (UPR), an adaptive signalling pathway to promote cell survival upon accumulation of unfolded protein in the endoplasmic reticulum (ER). Protein kinase-like endoplasmic reticulum kinase (PERK) signals one component of the UPR through phosphorylation of eukaryotic initiation factor 2 on the α-subunit (eIF2α) to attenuate protein synthesis, thereby reducing the biosynthetic burden. β-Cells uniquely require PERK-mediated phosphorylation of eIF2α to preserve cell function. Unabated protein synthesis in β-cells is sufficient to initiate a cascade of events, including oxidative stress, that are characteristic of β-cell failure observed in type 2 diabetes. In contrast to acute adaptive UPR activation, chronic activation increases expression of the proapoptotic transcription factor CAAT/enhancer-binding protein homologous protein (CHOP). Chop deletion in insulin-resistant mice profoundly increases β-cell mass and prevents β-cell failure to forestall the progression of diabetes. The findings suggest an unprecedented link by which protein synthesis and/or misfolding in the ER causes oxidative stress and should encourage the development of novel strategies to treat diabetes.