Phosphorylation of 4.1N by CaMKII Regulates the Trafficking of GluA1-containing AMPA Receptors During Long-term Potentiation in Acute Rat Hippocampal Brain Slices

OBJECTIVE

GluA1-containing α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors (AMPARs) inserted into postsynaptic membranes are key to the process of long-term potentiation (LTP). Some evidence has shown that 4.1N plays a critical role in the membrane trafficking of AMPARs. However, the underlying mechanism behind this is still unclear. We investigated the role of 4.1N-mediated membrane trafficking of AMPARs during theta-burst stimulation long-term potentiation (TBS-LTP), to illustrate the molecular mechanism behind LTP.

METHODS

LTP was induced by TBS in rat hippocampal CA1 neuron. Tat-GluA1 (MPR), which disrupts the association of 4.1N-GluA1, and autocamtide-2-inhibitory peptide, myristoylated (Myr-AIP), a CaMKII antagonist, were used to explore the role of 4.1N in the AMPARs trafficking during TBS-induced LTP. Immunoprecipitation (IP) and immunoblotting (IB)were used to detect protein expression, phosphorylation, and the interaction of p-CaMKII-4.1N-GluA1.

RESULTS

We found that Myr-AIP attenuated increases of p-CaMKII (T286), p-GluA1 (ser831), and 4.1N phosphorylation after TBS-LTP, and decreased the association of p-CaMKII-4.1N-GluA1, along with the expression of GluA1, at postsynaptic densities during TBS-LTP. We also designed interfering peptides to disrupt the interaction between 4.1N and GluA1, which showed that Tat-GluA1 (MPR) or Myr-AIP inhibited TBS-LTP and attenuated increases of GluA1 at postsynaptic sites, while Tat-GluA1 (MPR) or Myr-AIP had no effects on miniature excitatory postsynaptic currents (mEPSCs) in non-stimulated hippocampal CA1 neurons.

CONCLUSION

Active CaMKII enhanced the phosphorylation of 4.1N and facilitated the association of p-CaMKII with 4.1N-GluA1, which in turn resulted in GluA1 trafficking during TBS-LTP. The association of 4.1N-GluA1 is required for LTP, but not for basal synaptic transmission.

[Serum glycocalyx markers in patients after cardiac arrest: association with outcomes]

Objective: To assess the levels of serum glycocalyx markers in the first 24 hours after cardiac arrest (CA) and investigate their relationship with 30-day outcomes. Methods: A retrospective cohort study was conducted on prospectively collected data from CA patients, who were admitted to the intensive care units of the Affiliated Hospital of Xuzhou Medical University and obtained return of spontaneous circulation for more than 24 hours between September 2021 and October 2022. Serum samples obtained at the 24-hour after CA were utilized to measure the levels of glycocalyx markers, including heparan sulfate (HS), hyaluronic acid (HA), and syndecan-1 (Sdc-1). Patients were allocated into good function (CPC1-2) and poor function (CPC3-5) groups on the basis of cerebral performance category (CPC) at 30 days post-CA. Logistic regression analysis was used to determine the association between serum glycocalyx markers and neurological outcomes. Patients were regrouped in light of 30-d mortality and Cox regression analysis was used to determine the association between serum glycocalyx markers and 30-d mortality. Results: A total of 71 patients were included in the study, including 31 (43.7%) females and 40 (56.3%) males, with an average age of (59.0±17.0) years. The poor function group (n=49) demonstrated significantly elevated levels of HS and HA when compared to the good function group (n=22) [HS: 2 461.0(1 623.0, 5 492.0) μg/L vs 1 492.0 (914.0, 2 550.0) μg/L, P=0.008; HA: 124.0(97.0, 365.0)μg/L vs 337.0(135.0, 1 421.0) μg/L, P=0.033]. Adjusted logistic regression analysis revealed that HS was independently associated with poor neurological outcome [odds ratio (OR)=0.389, 95% confidence interval (CI): 0.182-0.828, P=0.014]. In the 30-day mortality analysis, the death group (n=32) exhibited significantly higher levels of HS and HA when compared to the survival group (n=39) [HS: 1 880.0(1 011.0, 3 554.0) μg/L vs 2 500.0(1 726.0, 6 276.0) μg/L, P=0.027; HA: 162.0(99.0, 537.0) μg/L vs 813.0(148.0, 1 531.0) μg/L, P=0.025]. Adjusted Cox regression analysis indicated that elevated levels of HS and HA were independent risk factors (HS: HR=1.697, 95%CI: 1.126-2.557, P=0.011; HA: HR=1.336, 95%CI: 1.047-1.705, P=0.020) for 30-day mortality. Conclusions: High level of serum HS in 24 hours after CA may serve as a potential predictive marker for both neurological function and 30-day mortality. However, high level of serum HA appears to primarily predict 30-day mortality. Sdc-1 does not seem to contribute to outcome prediction.

[Research advances on severe burn infection and cytokine storm]

Mortality due to severe burns has always been at a high level. A large number of studies have shown that the rapid onset of infectious symptoms and rapid progression of severely burned patients are closely related to the occurrence of cytokine storm. However, in clinical practice, cytokine storm monitoring, early warning, and symptomatic treatment are still in exploratory stage. This article reviews the cytokine storm and its related cytokines, the mechanism, early warning, and treatment of cytokine storm induced by burn infection, aiming to provide clinical references for reducing infection and mortality in severely burned patients.

Overexpression of vascular endothelial growth factor enhances the neuroprotective effects of bone marrow mesenchymal stem cell transplantation in ischemic stroke

Although bone marrow mesenchymal stem cells (BMSCs) might have therapeutic potency in ischemic stroke, the benefits are limited. The current study investigated the effects of BMSCs engineered to overexpress vascular endothelial growth factor (VEGF) on behavioral defects in a rat model of transient cerebral ischemia, which was induced by middle cerebral artery occlusion. VEGF-BMSCs or control grafts were injected into the left striatum of the infarcted hemisphere 24 hours after stroke. We found that compared with the stroke-only group and the vehicle- and BMSCs-control groups, the VEGF-BMSCs treated animals displayed the largest benefits, as evidenced by attenuated behavioral defects and smaller infarct volume 7 days after stroke. Additionally, VEGF-BMSCs greatly inhibited destruction of the blood-brain barrier, increased the regeneration of blood vessels in the region of ischemic penumbra, and reducedneuronal degeneration surrounding the infarct core. Further mechanistic studies showed that among all transplant groups, VEGF-BMSCs transplantation induced the highest level of brain-derived neurotrophic factor. These results suggest that BMSCs transplantation with vascular endothelial growth factor has the potential to treat ischemic stroke with better results than are currently available.

[Application of near infrared fluorescence imaging in detection of residual cancer in oral squamous cell carcinoma]

Objective: Local recurrence is the main cause of treatment failure in patients with oral squamous cell carcinoma (OSCC). This study was proposed to investigate the feasibility of near infrared fluorescence (NIF) via indocyanine green (ICG) for monitoring surgical marginal in operation for OSCC patients. Methods: In 35 patients with OSCC treated surgically in the Department of Oral and Maxillofacial Surgery, Nanjing University School of Medicine, from January 2019 to June 2020, ICG (0.75 mg/kg) was administered intravenously via elbow vein at (12±1) hours before surgery, and NIF was performed intraoperatively on the surgical field and the cut edge of the surgically excised specimen, and fluorescence intensity was measured for OSCC tissue and normal oral mucosa, abnormal fluorescence signals were taken and subjected to rapid cryopathological examination. Correlation between NIF tumor boundary grading and pathological tumor boundary grading was analyzed by Spearman correlation analysis. Results: Clear ICG NIF was obtained for tumor lesions in all 35 patients, with a positive rate of 100%. The fluorescence intensity of OSCC tissue was (412.73±146.56) au, which was higher than that of normal oral mucosa tissue [(279.38±82.56) au, P<0.01]. Abnormal fluorescence signals were detected at the tumor bed and the cut edge of the surgical resection specimen in 4 patients, of which 2 cases were pathologically confirmed as cancer cell residue and 2 cases as inflammatory cell infiltration. The rate of positive detection of cut margins using ICG NIF technique in OSCC was 5.7% (2/35). Twenty of the 35 OSCC patients had grade 1, 11 of grade 2, and 4 of grade 3 tumor borders revealed by NIF of surgical resection specimens, which was positively correlated with pathological tumor border (r=0.809, P<0.001). Conclusions: ICG NIF technique can effectively detect the residual cancer cells at the incision margin, which is of great clinical value in reducing local recurrence of OSCC after surgery due to intraoperative cancer residue.

Hydrostatic pressure stimulates the osteogenesis and angiogenesis of MSCs/HUVECs co-culture on porous PLGA scaffolds

In native bone tissue regeneration, blood vessels, providing oxygen and nutrition for tissues, can promote the regeneration of bone and accelerate the repair of a defected area. In this study, Poly(D, L-lactic-co-glycolic acid) (PLGA) inverse opal scaffolds with high pore interconnectivity were fabricated and further modified with vascular endothelial growth factor (VEGF). The rat bone marrow derived mesenchymal stem cells (rMSCs) and human umbilical vein endothelial cells (HUVECs) were co-cultured onto the scaffolds to enhance vascularization for bone tissue regeneration. Cell attachment, viability, proliferation, and morphology were detected by cell counting kit-8 (CCK-8) assay, live and dead staining and scanning electron microscopy (SEM). Hydrostatic pressure with 0-279 KPa and 1 Hz one hour per day for 7 days was applied to tissue engineered bone constructs to investigate whether the loading stimulation can promote osteogenesis and angiogenesis mutually evaluated in parallel by multiple in vitro assays and in an in vivo chicken chorioallantoic membrane (CAM) model. The results indicated that the immobilization of VEGF can improve biocompatibility of PLGA scaffolds and promote cell attachment and proliferation. The cell-scaffold constructs showed higher CD31 expression because of the angiogenic differentiation of rMSCs in hydrostatic loading culture condition in vitro. The in vivo CAM model experiment demonstrated that hydrostatic loading stimulated angiogenic differentiation of rMSCs can accelerate tubulogenesis. Furthermore, the new capillaries formed in cell-scaffold constructs were conducive to calcium deposition in vivo.

[Investigation on noise exposure level and health status of workers in transportation equipment manufacturing industry]

Objective: To explore the noise exposure level and the health status of workers in transportation equipment manufacturing industry, and provide a scientific basis for guidance and implementation of intervention measures. Methods: From January to December in 2019, a total of 2088 noise workers from a large enterprise were selected by cluster sampling method in railway transportation equipment manufacturing, automobile manufacturing and aerospace aircraft manufacturing enterprises. The worker's noise exposure level was detected. Occupational health checkups were performed on the noise workers including electrical audiometry, blood pressure and electrocardiogram. χ(2) test and trend χ(2) test were used to analyze the data. Results: The noise exposure level of 66.9% (1396/2088) workers exceeded 85 dB (A) , and the median noise level was 87.9 (84.3-90.3) dB (A) . Among them, workers of railway transportation equipment manufacturing enterprises had the highest noise exposure level[89.9 (87.8-91.6) dB (A) ]. The detection rate of high-frequency hearing loss, abnormal blood pressure and abnormal electrocardiogram of noise workers were 15.7% (327/2088) , 18.1% (378/2088) and 6.1% (128/2088) , respectively. The differences in the detection rates of high-frequency hearing loss, abnormal blood pressure, and abnormal electrocardiogram in workers of railway transportation equipment manufacturing enterprises, automobile manufacturing enterprises, and aerospace manufacturing enterprises were statistically significant (P<0.05) . Workers of railway transportation equipment manufacturing enterprises had higher detection rates of high-frequency hearing loss (17.6%, 186/1056) . Workers of aerospace manufacturing enterprises had higher detection rates of abnormal blood pressure and abnormal electrocardiogram (26.3%, 169/642; 10.0%, 64/642) . The differences in the detection rates of high-frequency hearing loss, abnormal blood pressure and abnormal electrocardiogram of noise workers were statistically significant in different age and working age groups, and gradually increased with age and working age (P<0.05) . The difference in the detection rate of high-frequency hearing loss of noise workers was statistically significant in different noise intensity groups, and the overall trend was increasing (P<0.05) . Conclusion: The transportation equipment manufacturing industry has serious noise hazards, especially the railway transportation equipment manufacturing industry. Long-term occupational noise exposure can adversely affect workers' hearing and cardiovascular system. Enterprises should strengthen occupational health inspections, and at the same time, take personal protective measures to protect the health of workers.

Effect of different types of sugar on gut physiology and microbiota in overfed goose

To explored the difference of goose fatty liver formation induced-by different types of sugar from the intestinal physiology and the gut microflora, an integrated analysis of intestinal physiology and gut microbiota metagenomes was performed using samples collected from the geese including the normal-feeding geese and the overfed geese which were overfed with maize flour or overfeeding dietary supplementation with 10% sugar (glucose, fructose or sucrose, respectively), respectively. The results showed that the foie gras weight of the fructose group and the sucrose group was heavier (P < 0.05) than other groups. Compared with the control group, the ileum weight was significantly higher (P < 0.01), and the cecum weight was significantly lower in the sugar treatment groups (P < 0.001). Compared with the control group, the ratio of villi height to crypt depth in the fructose group was the highest in jejunum (P < 0.05); the trypsin activity of the ileum was higher in the fructose group and the sucrose group (P < 0.05). At the phylum level, Firmicutes, Proteobacteria and Bacteroidetes were the main intestinal flora of geese; and the abundance of Firmicutes in the jejunum was higher in the sugar treatment groups than that of the maize flour group. At the genus level, the abundance of Lactobacillus in the jejunum was higher (P < 0.05) in the sugar treatment groups than that of the maize flour group. In conclusion, forced-feeding diet supplementation with sugar induced stronger digestion and absorption capacity, increased the abundance of Firmicutes and Bacteroidetes and the abundance of Lactobacillus (especially fructose and sucrose) in the gut. So, the fructose and sucrose had higher induction on hepatic steatosis in goose fatty liver formation.

[Analysis of hearing surveillance of noise-exposed workers in Zhuzhou city]

Objective: To understand the hearing loss status of workers exposed to noise, and provide a scientific basis for formulating effective prevention and control strategies. Methods: From Januaryl to October 31 , 2018, through the occupational hazard declaration and record management system of the workplace and the health checkup system , the basic information and physical examination information of 7806 noise-exposed workers in 136 companies in Zhuzhou City in 2018 and the related information about the industry, type, and scale of the enterprises were collected. The χ(2) test was used to analyze the occupational health monitoring data of the noise-exposed workers. Results: The average age of 7806 workers in Zhuzhou was(36. 1±9. 3) years, and the working age was 7. 0(3. 0, 11. 0) years. And 1 270 workers with noise induced hearing loss(NIHL) were detected, including 51 suspected occupational noise deafness. The detection rates of NIHL and the suspected occupational noise deafness were 16. 27% , 0. 65% , respectively. The detection rate of noise was 0.01% in 1deaf person. It showed that the male had higher morbidity than the female (P<0. 05) and the workers with longer exposure time had a higher morbidity (P<0. 05) . There was a statistically significant difference in the detection rate of NIHL and suspected occupational noise deafness between workers of different types of work (P<0. 05 ) . It was noted that the morbidity varied in different enterprises, industry types and terms of scales (P<0. 05 ) . Non- metal ore mining and dressing industry workers had higher NIHL detection rate (33. 33%, 14/42) and small companies workers had higher NIHL detection rate(19. 32%, 296/1532) . There was a statistically significant difference in the detection rate of suspected occupational noise deafness between workers of different economic types of enterprises. There was a high detection rate of suspected occupational noise deafness among workers in private enterprises(1. 29%, 36/2782) . Conclusion: The noise operation in Zhuzhou is seriously endangered.Occupational health protection measures for non-metallic mining and dressing industries, small and private enterprises should be strengthened.Occupational health law enforcement efforts should be strengthened to protect workers' health.

Comparing hydroxyapatite with osteogenic medium for the osteogenic differentiation of mesenchymal stem cells on PHBV nanofibrous scaffolds

Having advantageous biocompatibility and osteoconductive properties known to enhance the osteogenic differentiation of mesenchymal stem cells (MSCs), hydroxyapatite (HA) is a commonly used material for bone tissue engineering. What remains unclear, however, is whether HA holds a similar potential for stimulating the osteogenic differentiation of MSCs to that of a more frequently used osteogenic-inducing medium (OIM). To that end, we used PHBV electrospun nanofibrous scaffolds to directly compare the osteogenic capacities of HA with OIM over MSCs. Through the observation of cellular morphology, the staining of osteogenic markers, and the quantitative measuring of osteogenic-related genes, as well as microRNA analyses, we not only found that HA was as capable as OIM for differentiating MSCs down an osteogenic lineage; albeit, at a significantly slower rate, but also that numerous microRNAs are involved in the osteogenic differentiation of MSCs through multiple pathways involving the inhibition of cellular proliferation and stemness, chondrogenesis and adipogenesis, and the active promotion of osteogenesis. Taken together, we have shown for the first time that PHBV electrospun nanofibrous scaffolds combined with HA have a similar osteogenic-inducing potential as OIM and may therefore be used as a viable replacement for OIM for alternative in vivo-mimicking bone tissue engineering applications.

[A cohort study on body mass index and risk of all-cause mortality among hypertensive population]

Objective: To investigate the relationship between body mass index (BMI) and all-cause mortality in hypertensive population. Methods: All participants were selected from a prospective cohort study based on a rural population from Henan province, China. Cox proportional hazards regression models were used to estimate the associations of different levels of BMI stratification with all-cause mortality. Restricted cubic spline models were used to detect the dose-response relation. Results: Among the 5 461 hypertensive patients, a total of 31 048.38 person-years follow-up was conducted. The median of follow-up time was 6 years, and 589 deaths occurred during the follow-up period. Compared to normal weight group (18.5 kg/m(2)<BMI<24.0 kg/m(2)) the multivariate-adjusted hazard ratios for all-cause mortality associated with BMI levels (<18.5 kg/m(2), 24-28 kg/m(2), and ≥28 kg/m(2)) were 0.83 (95%CI: 0.37-1.87), 0.81 (95%CI: 0.67-0.97), and 0.72 (95%CI: 0.56-0.91), respectively. The dose-response analysis showed a nonlinear, reverse "S" shaped relationship (non-linearity P<0.001). Conclusion: Overweight or obese might have a protective effect on all-cause mortality in hypertensive population, which supports the "obesity paradox" phenomenon.

[A preliminary evaluation of mental status and an investigation of occupational health knowledge demand in operating and maintenance personnel in wind power plants]

Objective: To investigate the mental status, level of occupational health knowledge, health behaviors, and occupational health knowledge demand in operating and maintenance personnel in wind power plants, and to provide a basis for formulating protective measures of occupational health for operating and maintenance personnel in wind power plants. Methods: A cluster sampling was performed in regionally representative wind power plants in the wind power industry from May 2014 to June 2015, and the Symptom Checklist-90 (SCL-90) and a self-made evaluation questionnaire were used to investigate the general status, mental health, and occupational health knowledge demand in 160 operating and maintenance workers. Results: Of all respondents, 26.9% had mental health issues. The awareness rate of infectious disease knowledge and preventive measures was 11.9%. Of all workers, 96.5% wanted to know the occupational hazard factors in the workplace, and 96.3% wanted to get the knowledge of the prevention of related diseases. Conclusion: Mental health issues in operating and maintenance personnel in wind power plants cannot be neglected and there is a high demand for occupational health services and related knowledge. Comprehensive intervention measures for health promotion in the workplace should be adopted to improve working environment, enhance individual mental health education, increase the level of occupational health management, and protect the health of workers.

The treatment of spinal cord injury in rats using bone marrow-derived neural-like cells induced by cerebrospinal fluid

This study aimed to evaluate the effect of bone mesenchymal stem cells (BMSCs) and BMSC neural-like cells (BMSC-Ns) on the spinal cord injury (SCI) in the rat model of SCI. BMSC-Ns were prepared from the third passage of BMSCs by induction of healthy cerebrospinal fluid (CSF) of an adult human. The SCI rat model was established through a surgical procedure, and after 7 days the rats were randomly divided into 3 (A, B and C) groups. Groups A (BMSC-Ns) and B (BMSCs) were treated with 1 × 10⁶/20 μl cells, while group C (saline) was treated with saline, all via intracerebroventricular injection. After transplantation, the BBB score of group A was significantly higher than that of group B, which in turn was significantly higher than that of group C (P < .05). The levels of Bdnf, Ngf, Ntf3 were statistically significantly higher in group A than those in groups B and C (P < .05). The levels of 5-HT, NA, Ach, DA, GABA in group A were significantly higher than those in groups B and C, whereas the level of Glu was significantly lower in group A than that in groups B and C (P < .05). The histopathological data showed remarkably less necrosis of the spinal cord in group A, compared to that in groups B and C. Transplanting BMSC-Ns or BMSCs into the lateral ventricles improved the neurological function of rats with SCI. Moreover, BMSC-Ns were significantly more effective than BMSCs, which provides a possible approach for the treatment of SCI.

Effects of nonglycosylated and glycosylated prolactin on basal and gonadotropin-stimulated steroidogenesis in chicken ovarian follicles

In galliformes, the circulating isoform of prolactin (PRL) significantly changes during different reproductive states. However, the role of the major isoform (glycosylated PRL [G-PRL]) in ovarian steroidogenesis is unknown. The present study aimed to compare the effects of nonglycosylated (NG-) and G-PRL on basal and gonadotropin-stimulated estradiol (E₂) and progesterone (P₄) production in granulosa cells or follicular walls of chicken of different size class follicles. In the initial experiment, granulosa cells of preovulatory F3-F1 and prehierarchical 6- to 8-mm follicles were incubated for 24 h with different concentrations of NG- or G-PRL (0, 1, 10, 100, or 1,000 ng/mL). In the subsequent experiments, these categorized granulosa cells and follicular walls of prehierarchical 4-6, 2-4, and <2-mm follicles were incubated for 24 h in the absence and presence of 10-ng/mL FSH or LH, or in combination with different concentrations of NG- or G-PRL (10, 100, or 1,000 ng/mL). We observed that lower levels of NG-PRL induced (P < 0.05) E₂ and P₄ secretion in granulosa cells of either preovulatory or prehierarchical follicles, but at higher levels, this effect was reduced. In contrast, G-PRL promoted (P < 0.05) basal E₂ and P₄ secretion in preovulatory granulosa cells but was inhibitory (P < 0.05) in prehierarchical granulosa cells. Results obtained by real-time quantitative PCR (qPCR) demonstrated that these effects were mediated through modulation of the expression of StAR, CYP11A1, CYP19A1, and 3β-HSD. Furthermore, G-PRL was less potent than NG-PRL in inhibiting FSH- or LH-stimulated E₂ and P₄ production in granulosa cells of preovulatory follicles, whereas NG-PRL enhanced (P < 0.05) but G-PRL reduced (P < 0.05) FSH-induced P₄ production in those of prehierarchical follicles. In follicular walls from each group of prehierarchical 4-6, 2-4, and <2-mm follicles, NG- and G-PRL had both stimulatory and inhibitory influences on the actions of FSH on E₂ and P₄ secretion, but both suppressed (P < 0.05) LH-induced E₂ and P₄ secretion except for the synergistic effects of LH and G-PRL on P₄ secretion by follicular walls of the follicles of 4-6 mm. Taken together, these results suggest that both NG- and G-PRL are biologically active in regulating basal and gonadotropin-stimulated E₂ and P₄ production in chicken ovarian follicles. However, their effects are different depending on the concentration, the type of gonadotropin (FSH or LH), and the stage of follicle development.

[The clinical features of patients with allergic rhinitis of Nantong city in China]

Objective:To comprehensively analyze the clinical features of patients with AR by a retrospective study. Method:A total number of 8 102 patients diagnosed with AR were enrolled in Nantong area, and detailed clinical data were documented in all cases. Skin prick tests with standardized aeroallergens were conducted in these patients; The samples were divided into two groups(children and adults group) and the clinical features between two groups were analysed. Result:Children in schoolage were the majority of AR patients in children group. There were 4 581 cases(56.54%) with ocular symptoms, 3 977 cases(49.09%)with lower respiratory tract symptoms. Nasal congestion (97.37%) was the most common symptoms in patients with AR,while eye itching(32.68%) was the most common ocular symptoms in patients with AR, followed by the dacryorrhea(23.57%);and cough(44.72%) was the most common lower respiratory tract symptoms. Dermatophagoides pteronyssinus and dermatophagoides farinae had the highest positivity among all allergens, and the shrimp was the main food allergen. Conclusion:We analyzed the clinical features of patients with AR, that would provide a more scientific basis for prevention,clinical diagnosis, treatment and epidemiological studies for AR.

In Vitro Differentiation of Bone Marrow Mesenchymal Stem Cells into Neuron-Like Cells by Cerebrospinal Fluid Improves Motor Function of Middle Cerebral Artery Occlusion Rats

Bone marrow mesenchymal stem cells (BMSCs) represent a promising tool for stem cell-based therapies. However, the majority of BMSC transplants only allow for limited recovery of the lost functions. We previously found that human cerebrospinal fluid (hCSF) is more potent than growth factors in differentiating human BMSCs into neuron-like cells in vitro. In this study, we studied the effect of transplantation of rat BMSC-derived neuron-like cells (BMSC-Ns) induced by hCSF into rat brain with middle cerebral artery occlusion (MCAO). The survival and differentiation of the transplanted cells were determined using immunofluorescence staining of bromodeoxyuridine. The recovery of neurological function were observed by the modified neurological severity score (modified NSS) at 4, 15, and 32 days after cell transplantation, HE staining for determination of the infarct volume at day 32 after cell transplantation. Transplantation of BMSC-Ns or BMSCs significantly improved indexes of neurological function and reduced infarct size in rats previously subjected to MCAO compared with those in the control group. Remarkably, 32 days after transplantation, rats treated with BMSC-Ns presented a smaller infarct size, higher number of neuron-specific, enolase-positive, and BrdU-positive cells, and improved neurological function compared with BMSC group. Our results demonstrate that transplantation of hCSF-treated BMSC-Ns significantly improves neurological function and reduces infarct size in rats subjected to MCAO. This study may pave a new avenue for the treatment of MCAO.

Losartan improves the distribution and efficacy of doxorubicin in CT26 tumor

OBJECTIVE

The effectiveness of chemotherapeutic agents is impaired by limited delivery of chemotherapeutic agents to the tumor cells. Improving drug penetration in tumor tissues is very important. We tested whether losartan, a selective antagonist against type 1 angiotensin II receptors (AT1R) with noted antifibrotic activity, can enhance the penetration and efficacy of doxorubicin.

MATERIALS AND METHODS

BALB/C mice, which implanted with CT26 tumor cells, were divided into four groups: control, doxorubicin alone, losartan alone and doxorubicin + losartan combination groups. At day 0, the losartan alone and doxorubicin + losartan combination groups received losartan; and at day 8, the doxorubicin alone and doxorubicin + losartan combination groups received doxorubicin i.v. Tumor growth and intratumoral distribution of doxorubicin were evaluated. The mechanism underlying the enhanced anti-tumor effect of the combination of doxorubicin and losartan was investigated by immunohistochemical analysis.

RESULTS

Treatment with losartan alone did not suppress tumor growth; In contrast, treatment with doxorubicin alone decreased tumor growth; losartan and doxorubicin were administered in combination, had a synergistic effect that the tumor growth was much more inhibited. The decreased proliferation as indicated by down-regulation of Ki67, and increased apoptosis as indicated by TUNEL and caspase-3 staining. The expression of tumor suppressor gene P53 increased in doxorubicin + losartan combination groups.

CONCLUSIONS

Losartan can increase the therapeutic effectiveness of doxorubicin, yielding more great antitumor benefit. This study provided a rationale for initiating clinical trials using losartan in combination with chemotherapeutic agents to increase their therapeutic effectiveness.

Early third trimester maternal response to glucose challenge and pregnancy outcome in Chinese women-relationship between upper distribution level and recommended diagnostic criteria

BACKGROUND/OBJECTIVES

The objective of this study was to examine the relationship between upper distribution levels of glucose values in the 75-g oral glucose tolerance test (OGTT) and recommended diagnostic criteria for gestational diabetes mellitus (GDM) and adverse pregnancy outcomes.

SUBJECTS/METHODS

The distribution of the OGTT 2-h values of 13,501 pregnant women, which were below the World Health Organization (WHO) threshold for overt diabetes mellitus (DM), and managed in one teaching hospital in China, was reviewed and related to maternal characteristics and pregnancy outcomes.

RESULTS

For the entire group, the 90th and 95th percentile values of the OGTT 2-h glucose level, respectively, were close to the diagnostic cutoff values of the WHO and International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria. For adverse maternal outcomes, glucose level above the 90th percentile value was associated with increased hypertensive disorders, whereas no difference was seen with cutoff using the 95th percentile value. For perinatal outcomes, the 90th percentile was associated with increased neonatal intensive care unit admission and hypoglycemia, whereas the 95th percentile showed in addition association with phototherapy for jaundice and 5th-minute Apgar score <7. Although no differences in the incidence of adverse pregnancy outcomes were found using the different cutoffs, the >95th percentile cutoff value would have missed out 33.3-56.7% of the cases of adverse outcomes that would otherwise have been attributed to GDM.

CONCLUSIONS

Further studies are warranted to clarify which diagnostic criterion is most appropriate universally to identify adverse pregnancy outcomes attributed to GDM, and which could be mitigated with treatment specific for GDM.

S-nitrosylation of c-Src via NMDAR-nNOS module promotes c-Src activation and NR2A phosphorylation in cerebral ischemia/reperfusion

Previous studies suggested that activated c-Src promote the tyrosine phosphorylation of NMDA receptor subunit NR2A, and thus aggravate the injury induced by transient cerebral ischemia/reperfusion (I/R) in rat hippocampus CA1 region. In this study, we examined the effect of nitric oxide (NO) on the activation of c-Src and the tyrosine phosphorylation of NMDA receptor NR2A subunit. The results show that S-nitrosylation and the phosphorylation of c-Src were induced after cerebral I/R in rats, and administration of nNOS inhibitor 7-NI, nNOS antisense oligonucleotides and exogenous NO donor sodium nitroprusside diminished the increased S-nitrosylation and phosphorylation of c-Src during cerebral I/R. The cysteine residues of c-Src modified by S-nitrosylation are Cys489, Cys498, and Cys500. On the other hand, NMDAR antagonist MK-801 could attenuate the S-nitrosylation and activation of c-Src. Taken together, the S-nitrosylation of c-Src is provoked by NO derived from endogenous nNOS, which is activated by Ca(2+) influx from NMDA receptors, and promotes the auto-phosphorylation at tyrosines and further phosphorylates NR2A. The molecular mechanism we outlined here is a novel postsynaptic NMDAR-nNOS/c-Src-mediated signaling amplification, the 'NMDAR-nNOS → NO → SNO-c-Src → p-c-Src → NMDAR-nNOS' cycle, which presents the possibility as a potential therapeutic target for stroke treatment.

S-nitrosylation of mixed lineage kinase 3 contributes to its activation after cerebral ischemia

Previous studies in our laboratory have shown that mixed lineage kinase 3 (MLK3) can be activated following global ischemia. In addition, other laboratories have reported that the activation of MLK3 may be linked to the accumulation of free radicals. However, the mechanism of MLK3 activation remains incompletely understood. We report here that MLK3, overexpressed in HEK293 cells, is S-nitrosylated (forming SNO-MLK3) via a reaction with S-nitrosoglutathione, an exogenous nitric oxide (NO) donor, at one critical cysteine residue (Cys-688). We further show that the S-nitrosylation of MLK3 contributes to its dimerization and activation. We also investigated whether the activation of MLK3 is associated with S-nitrosylation following rat brain ischemia/reperfusion. Our results show that the administration of 7-nitroindazole, an inhibitor of neuronal NO synthase (nNOS), or nNOS antisense oligodeoxynucleotides diminished the S-nitrosylation of MLK3 and inhibited its activation induced by cerebral ischemia/reperfusion. In contrast, 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (an inhibitor of inducible NO synthase) or nNOS missense oligodeoxynucleotides did not affect the S-nitrosylation of MLK3. In addition, treatment with sodium nitroprusside (an exogenous NO donor) and S-nitrosoglutathione or MK801, an antagonist of the N-methyl-D-aspartate receptor, also diminished the S-nitrosylation and activation of MLK3 induced by cerebral ischemia/reperfusion. The activation of MLK3 facilitated its downstream protein kinase kinase 4/7 (MKK4/7)-JNK signaling module and both nuclear and non-nuclear apoptosis pathways. These data suggest that the activation of MLK3 during the early stages of ischemia/reperfusion is modulated by S-nitrosylation and provides a potential new approach for stroke therapy whereby the post-translational modification machinery is targeted.

Positive modulation of AMPA receptors prevents downregulation of GluR2 expression and activates the Lyn-ERK1/2-CREB signaling in rat brain ischemia

alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) are responsible for excitotoxicity induced by ischemic injury in hippocampal CA1 neurons, whereas the molecular mechanisms responsible for their neurotrophic activities are much less studied. Here, we examined the neuroprotective effect of positive modeulation of AMPARs by coapplication of AMPA with PEPA, an allosteric potentiator of AMPARs. We showed that coapplication of AMPA with PEPA protected hippocampal CA1 neurons from brain ischemia-induced death. Coapplication of AMPA with PEPA could prevent downregulated expression of GluR2 subunit caused by ischemia and increase BDNF expression via Lyn-ERK1/2-CREB signaling. Furthermore, TrkB receptor-mediated PI3K/Akt signal pathway was activated after coapplication of AMPA with PEPA, which was related to MAPK pathway and protected CA1 neurons against ischemic insults through depression of JNK3 activity, release of cytochrome c to cytosol and depression of capase-3 activity. Our results revealed that positive modulation of AMPARs could exert neuroprotective effects and the possible signaling pathways underlied.

Preparation of TiO(2)/Ag colloids with ultraviolet resistance and antibacterial property using short chain polyethylene glycol

TiO(2)/Ag nano-antibacterial material was prepared at low temperature using polyethylene glycol (PEG-600) as reducing and stabilizing agent. The size and shape as well as the optical properties of the nano-materials were characterized with transmission electron microscopy (TEM) and UV-vis spectroscopy (UV-vis). The results showed that the average particle size of TiO(2) among these nano-materials was around 50-150 nm, and the average particle size of nano-silver was around 20 nm. Formation of Ag nano-particles on the surface of TiO(2) was confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and the antibacterial activity was also investigated. By the antibacterial activity study and ultraviolet resistance test, it is noted that growth inhibition rates against E. coli was 99.99% as the concentration of nano-particles dispersion solution was 10 ppm, the minimum UV protective effect could be achieved as the concentration was 290 ppm.

Overexpression of the PDZ1 domain of PSD-95 diminishes ischemic brain injury via inhibition of the GluR6.PSD-95.MLK3 pathway

Recent studies have shown that kainate (KA) receptors are involved in neuronal cell death induced by seizure, which is mediated by the GluR6.PSD-95.MLK3 signaling module and subsequent JNK activation. In our previous studies, we demonstrated the neuroprotective role of a GluR6 c-terminus containing peptide against KA or cerebral ischemia-induced excitotoxicity in vitro and in vivo. Here, we first report that overexpression of the PDZ1 domain of PSD-95 protein exerts a protective role against neuronal death induced by cerebral ischemia-reperfusion in vivo and can prevent neuronal cell death induced by oxygen-glucose deprivation. Further studies show that overexpression of PDZ1 can perturb the interaction of GluR6 with PSD-95 and suppress the assembly of the GluR6.PSD-95.MLK3 signaling module and therefore inhibit JNK activation. Thus, it not only inhibits phosphorylation of c-Jun and down-regulates Fas ligand expression but also inhibits phosphorylation of 14-3-3 and decreases Bax translocation to mitochondria, decreases the release of cytochrome c, and decreases caspase-3 activation. Overall, the essential role of the PDZ1 domain of PSD-95 in apoptotic cell death in neurons provides an experimental foundation for gene therapy of neurodegenerative diseases with overexpression of the PDZ1 domain.

Targeted correction of point mutations in the low density lipoprotein receptor gene mediated by single-stranded oligonucleotides in vivo

This study was designed to investigate the repair of point mutations in the low density lipoprotein receptor (LDLR) gene mediated by single-stranded oligonucleotides (SSOs) in vivo. Mutations in the LDLR gene are known to be the prime cause of familial hypercholesterolemia (FH). SSOs result in sequence-specific alterations leading to the correction of mutations. In the present study, the LDLR gene with a nonsense mutation (c660x) was fused to a luciferase reporter gene (p660-LDLR-luc) and introduced into mouse liver by hydrodynamic gene transfer. These mice were then injected via the tail vein with different SSOs complexed with polyethylenimine. Firefly luciferase activity present in hepatic cell lysate was measured to analyze repair efficiency. Restriction fragment length polymorphism analysis and direct sequencing were performed to affirm that the LDLR mutation was corrected. The results indicate that the LDLR mutation was corrected in the liver in vivo only in the presence of antisense SSOs (anti-SSOs). Our findings provide initial evidence that the point mutation in p660-LDLR-luc can be corrected by anti-SSO targeted repair in vivo. This may be a potential strategy for the treatment of FH.

Overexpression of PDZ1 domain prevents apoptosis of rat hippocampal neurons induced by kainic acid

In our previous studies, Tat-GluR6-9c (a glutamate receptor 6 C-terminus peptide fused the TAT protein transduction sequence) not only inhibited the activation of MLK3 (mixed lineage kinase 3) and JNK (c-Jun N-terminal kinase) via the GluR6.PSD-95 (postsynaptic density protein 95).MLK3 signaling module but also diminished neuronal death induced by kainic acid or transient cerebral ischemia in rat hippocampus. Here, we investigate whether overexpression of the PDZ1 domain of PSD-95 protein could suppress the binding of GluR6 with PSD-95 and the activation of MLK3, MKK7 (mitogen-activated kinase kinase 7) and JNK1/2, and rescused neuronal cell death induced by kainic acid. Our results showed that overexpression of the PDZ1 domain of PSD-95 protein could prevent nuclear accumulation and abrogate neuronal cell death in SD (Sprague-Dawley) rat hippocampal neuronal cells. Further studies indicated that overexpression of PDZ1 could inhibit the enhancement of binding of GluR6 to PSD-95 and prevent the activation of MLK3, MKK7 and JNK1/2 induced by kainic acid. Taken together, the essential role of the PDZ1 domain of PSD-95 in apoptotic cell death in neurons provides an experimental foundation for gene therapy of neurodegenerative diseases with overexpression of the PDZ1 domain.

Activation of peripheral Th17 lymphocytes in patients with asthma

A recently identified interleukin (IL)-17-producing T-helper (Th) lymphocyte subset, which comprises Th17 cells producing hallmark cytokines IL-17A, IL-17F and IL-22, is involved in chronic inflammatory diseases. Elevated gene and protein expressions of IL-17 are manifested in allergic asthma. We further characterized the activation of Th17 cells in asthmatic patients. Peripheral blood mononuclear cells (PBMC) were purified from 31 asthmatic patients and 20 sex- and age-matched control subjects. The number of IL-17A secreting cells in peripheral blood was enumerated by enzyme-linked immunosorbent spot assay. Cell surface expression of Th17-related chemokine receptor CCR6, and plasma level of IL-17A, IL-17F and IL-22, and ex vivo production of IL-17A and IL-22 were measured by flow cytometry and enzyme-linked immunosorbent assay, respectively. The number of peripheral Th17 lymphocytes, expression of CCR6 on Th cells, and ex vivo IL-23, anti-CD3 and anti-CD28 induced production of IL-22 by PBMC were significantly elevated in asthmatic patients compared with control subjects (all p < 0.01). This clinical study further confirmed increased number of peripheral Th17 lymphocytes and cell surface expression of CCR6 receptors on Th cells in asthmatic patients. Pro-inflammatory cytokine IL-23 can exacerbate disease severity by activating pathogenic Th17 lymphocytes to release downstream inflammatory cytokine IL-22 in asthma.

[Overexpression of PDZ1 domain of PSD-95 protein rescues hippocampal neurons from apoptosis induced by oxygen-glucose deprivation]

To detect the effect of PDZ1, domain of postsynaptic density 95 (PSD-95), on apoptosis of hippocampal neurons induced by oxygen-glucose deprivation (OGD), Sprague-Dawley rat hippocampal neurons were infected with PDZ1-viruses after 21 days of plating. Twenty-four hours after infection, cells were treated with OGD for 1.5 h, then were incubated with DAPI and apoptosis-like cells were characterized, or were collected for co-immunoprecipitation and Western blot analyses. The results showed that: (1) PDZ1 overexpression was observed in hippocampal neurons; (2) Apoptosis induced by OGD was obviously decreased in neurons overexpressing PDZ1 (P<0.05); (3) Overexpression of PDZ1 prevented the binding of GluR6 to PSD-95; (4) Overexpression of PDZ1 inhibited MLK3 and JNK1/2 activation induced by OGD. These results indicate that overexpression of PDZ1 may prevent hippocampal neurons from apoptosis induced by OGD.

Cys74 and Cys163 are necessary for IL-18 to elicit IFN-gamma production from peripheral blood lymphoid mononuclear cells

There are four cysteines (Cys74, Cys104, Cys112 and Cys163) in mature human IL-18 (hIL-18). These cysteines are highly conserved in IL-18s of 11 species cloned so far, suggesting that one or more of the cysteines may be important for hIL-18 function. In this study, each cysteine residue was individually replaced with serine by site-directed mutagenesis. The wild type and mutant IL-18s were expressed in Escherichia coli and renatured by two renaturing methods. The purified wild type and mutant rhIL-18s were assayed for their capacity of inducing IFN-gamma and activating NF-kappaB from ConA-stimulated PBMC. DNA binding activity of NF-kappaB was performed by electrophoretic mobility-shift analysis. Our results showed that the mutant rhIL-18C74S and C163S induced much less amount of IFN-gamma from PBMC and the decrement of NF-kappaB DNA binding activity was also observed from C74S and C163S treated PBMC. These results indicate that functional hIL-18 has an absolute requirement for residues Cys74 and Cys163.

Identification of important amino acid residues for human IL-18 function by mutant construction

To study the structure-function relationship of IL-18, two IL-18 mutants, N- and C-terminal mutant (Delta NC) and IL-1 signature-like sequence mutant S(154)A/Y(156)F/E(157)P/C(163)T (S), were constructed by PCR. The wild type and mutant recombinant human interleukin-18 (rhIL-18) were expressed in E.coli, purified by Sephadex G-75 chromatography and renatured by stepwise dilution. The purity of the recombinant proteins was over 95%. The activities of wild type and mutant rhIL-18s were defined as the ability to induce interferon-gamma (IFN-gamma) production and NF-kappa B activation from human peripheral blood mononuclear cells (PBMC). Our results showed that the two mutants induced significantly less amount of IFN-gamma from PBMC (13%, 48% of wild type rhIL-18 for Delta NC, S, respectively), and the activation of NF-kappa B also lower than wild type rhIL-18(69.7%, 89.8% of wild type rhIL-18 respectively), indicating that the deleted or mutated amino acids might be important for IL-18 function.

Cloning, High Level Expression and Purification of Rat betaB2-crystallin

beta-crystallins are the largest group of lens structural proteins, which are necessary for both the high refractive index and the transparency of the eye lens, and have been implicated in various kinds of cataracts. To obtain abundant betaB2-crystallin for the study of the mechanism of their oligomerization, a bacterial expression system for betaB2-crystallin and a rapid method for its purification were developed. cDNA encoding rat betaB2-crystallin was cloned using RT-PCR. After the induction of recA promoter with nalidixic acid, abundant protein was produced in E. coli. betaB2-crystallin comprised about 30% of the total bacterial proteins and it is water-soluble. After anion-exchange chromatography on DEAE cellulose and gel filtration on Sephadex G-100, the protein was obtained pure as judged by SDS-PAGE. The high level expression and rapid purification of recombinant betaB2-crystallin will facilitate the further study of structure-function relationship of betaB2-crystallin.

Interleukin 18 High Level Expression in E.coli Purification and Renaturation of the Recombinant Protein

Using the total RNA extracted from mitogen-stimulated human peripheral blood mononuclear cells (PBMC) as template, the cDNA of interleukin 18 was amplified by RT-PCR. The cDNA was subsequently cloned into the expression vector pJW2 and sequenced. The recombinant human IL-18 (rhIL-18) was expressed efficiently in inclusion bodies in E.coli with the yield accounting for 20% total bacteria proteins. The inclusion bodies were washed with 2 mol/L urea and rhIL-18 was further purified using Sephadex G-100 column chromatography in 8 mol/L urea. After purification, the purity of rhIL-18 was greater than 90% as judged by SDS-PAGE. The purified rhIL-18 showed significant and dose-dependent IFN-gamma-inducing activity in human PBMC, in the presence of 0.5 mg/L Con A.

Activities of monomeric insulin analogs at position A8 are uncorrelated with their thermodynamic stabilities

Previous studies have demonstrated that the potency and thermodynamic stability of human insulin are enhanced in concert by substitution of Thr(A8) by arginine or histidine. These surface substitutions stabilize the N-terminal alpha-helix of the A chain, a key element of hormone-receptor recognition. Does enhanced stability necessarily imply enhanced activity? Here, we test by structure-based mutagenesis the relationship between the stability and activity of the hormone. To circumvent confounding effects of insulin self-association, A chain analogs were combined with a variant B chain (Asp(B10), Lys(B28), and Pro(B29) (DKP)) to create a monomeric template. Five analogs were obtained by chain combination; disulfide pairing proceeded in each case with native yield. CD and (1)H NMR spectra of the DKP analogs are essentially identical to those of DKP-insulin, indicating a correspondence of structures. Receptor binding affinities were determined by competitive displacement of (125)I-insulin from human placental membranes. Thermodynamic stabilities were measured by CD titration; unfolding was monitored as a function of guanidine concentration. In this broader collection of analogs receptor binding affinities are uncorrelated with stability. We suggest that receptor binding affinities of A8 analogs reflect local features of the hormone-receptor interface rather than the stability of the free hormone or the intrinsic C-capping propensity of the A8 side chain.

Hierarchical protein folding: asymmetric unfolding of an insulin analogue lacking the A7-B7 interchain disulfide bridge

The landscape paradigm of protein folding can enable preferred pathways on a funnel-like energy surface. Hierarchical preferences may be manifest as a nonrandom pathway of disulfide pairing. Stepwise stabilization of structural subdomains among on-pathway intermediates is proposed to underlie the disulfide pathway of proinsulin and related molecules. Here, effects of pairwise serine substitution of insulin's exposed interchain disulfide bridge (Cys(A7)-Cys(B7)) are characterized as a model of a late intermediate. Untethering cystine A7-B7 in an engineered monomer causes significantly more marked decreases in the thermodynamic stability and extent of folding than occur on pairwise substitution of internal cystine A6-A11 [Weiss, M. A., Hua, Q. X., Jia, W., Chu, Y. C., Wang, R. Y., and Katsoyannis, P. G. (2000) Biochemistry 39, 15429-15440]. Although substantially disordered and without significant biological activity, the untethered analogue contains a molten subdomain comprising cystine A20-B19 and a native-like cluster of hydrophobic side chains. Remarkably, A and B chains make unequal contributions to this folded moiety; the B chain retains native-like supersecondary structure, whereas the A chain is largely disordered. These observations suggest that the B subdomain provides a template to guide folding of the A chain. Stepwise organization of insulin-like molecules supports a hierarchic view of protein folding.

[Expression and purification of murine interleukin 18 in Escherichia coli and its antitumor effects]

Total RNA was extracted from murine hepatocytes, and the cDNA of interleukin 18(IL-18) was amplified by RT-PCR. The cDNA was introduced into the expression vector pJW2 and sequenced. Under heat induction, the recombinant murine IL-18(rmIL-18) was expressed in inclusion bodies in E. coli with the yield accounting for 18% of total bacteria proteins. The inclusion bodies were dissolved with 5 mol/L urea, and rmIL-18 was purified using Sephadex G-100 column chromatography. In the presence of 0.5 mg/L Con A, the purified rmIL-18 showed dose-dependent IFN-gamma-inducing activity in murine splenocytes. The purified rmIL-18 exhibited significant antitumor effects in Kunming mice challenged intraperitoneally (i.p.) with H22 hepatocarcinoma when administered 10 micrograms rmIL-18 i.p. on days 1, 4 after challenge, and the mice survived resisted the rechallenged with H22 cells.

Mini-proinsulin and mini-IGF-I: homologous protein sequences encoding non-homologous structures

Protein minimization highlights essential determinants of structure and function. Minimal models of proinsulin and insulin-like growth factor I contain homologous A and B domains as single-chain analogues. Such models (designated mini-proinsulin and mini-IGF-I) have attracted wide interest due to their native foldability but complete absence of biological activity. The crystal structure of mini-proinsulin, determined as a T3R3 hexamer, is similar to that of the native insulin hexamer. Here, we describe the solution structure of a monomeric mini-proinsulin under physiologic conditions and compare this structure to that of the corresponding two-chain analogue. The two proteins each contain substitutions in the B-chain (HisB10-->Asp and ProB28-->Asp) designed to destabilize self-association by electrostatic repulsion; the proteins differ by the presence or absence of a peptide bond between LysB29 and GlyA1. The structures are essentially identical, resembling in each case the T-state crystallographic protomer. Differences are observed near the site of cross-linking: the adjoining A1-A8 alpha-helix (variable among crystal structures) is less well-ordered in mini-proinsulin than in the two-chain variant. The single-chain analogue is not completely inactive: its affinity for the insulin receptor is 1500-fold lower than that of the two-chain analogue. Moreover, at saturating concentrations mini-proinsulin retains the ability to stimulate lipogenesis in adipocytes (native biological potency). These results suggest that a change in the conformation of insulin, as tethered by the B29-A1 peptide bond, optimizes affinity but is not integral to the mechanism of transmembrane signaling. Surprisingly, the tertiary structure of mini-proinsulin differs from that of mini-IGF-I (main-chain rms deviation 4.5 A) despite strict conservation of non-polar residues in their respective hydrophobic cores (side-chain rms deviation 4.9 A). Three-dimensional profile scores suggest that the two structures each provide acceptable templates for threading of insulin-like sequences. Mini-proinsulin and mini-IGF-I thus provide examples of homologous protein sequences encoding non-homologous structures.

Mapping the functional surface of insulin by design: structure and function of a novel A-chain analogue

Functional surfaces of a protein are often mapped by combination of X-ray crystallography and mutagenesis. Such studies of insulin have yielded paradoxical results, suggesting that the native state is inactive and reorganizes on receptor binding. Of particular interest is the N-terminal alpha-helix of the A-chain. Does this segment function as an alpha-helix or reorganize as recently proposed in a prohormone-convertase complex? To correlate structure and function, we describe a mapping strategy based on protein design. The solution structure of an engineered monomer ([AspB10, LysB28, ProB29]-human insulin) is determined at neutral pH as a template for synthesis of a novel A-chain analogue. Designed by analogy to a protein-folding intermediate, the analogue lacks the A6-A11 disulphide bridge; the cysteine residues are replaced by serine. Its solution structure is remarkable for segmental unfolding of the N-terminal A-chain alpha-helix (A1 to A8) in an otherwise native subdomain. The structure demonstrates that the overall orientation of the A and B chains is consistent with reorganization of the A-chain's N-terminal segment. Nevertheless, the analogue's low biological activity suggests that this segment, a site of clinical mutation causing diabetes mellitus, functions as a preformed recognition alpha-helix.

Insulin-like compounds related to the amphioxus insulin-like peptide

Three insulin-like compounds consisting of two disulfide-linked polypeptide chains have been synthesized. The A-chains of these compounds correspond either to the A- or to the A + D-domain of the putative amphioxus insulin-like peptide (amphioxus ILP), and their B-chains correspond either to the B-chain of insulin or to a slightly modified (i.e., [1-Thr]) B-domain of amphioxus ILP. The biological potency of these compounds was evaluated in mammalian cells or cell fractions containing either human or rat insulin receptors or human or mouse insulin-like growth factor I (IGF-I) receptors, with respect to binding affinity, insulin-like metabolic activity (lipogenesis), and growth factor activity (mitogenesis). Amphioxus ILP A/bovine insulin B and amphioxus ILP A + D/bovine insulin B exhibited potencies ranging from 2.0 to 9.8% relative to natural insulin, and both compounds were full agonists in lipogenesis assays, stimulating lipogenesis to the same maximal extent as seen with natural insulin. Amphioxus ILP A/amphioxus ILP [1-Thr]B stimulated lipogenesis with a potency of 0.01% relative to natural insulin. We consider this compound also likely to be a full agonist. In assays measuring binding to IGF-I receptors and stimulation of mitogenesis, these compounds displayed some activity although the activity was too low for exact quantification. These results suggest that amphioxus ILP has retained an overall structural similarity to mammalian insulin and IGF-I but has also accumulated substantial mutations which markedly reduce its ability to bind and activate their cognate receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

[Changes in water-soluble, urea-soluble and membrane intrinsic proteins in human senile cataract]

Gel filtration of water-soluble protein shows a substantial increase in HM+ alpha-crystallin and a marked decrease in beta- and gamma-crystallins in cortical cataract. A decrease in beta 1-crystallin in cortical punctate opaque lenses is also striking. In nuclear cataractous lenses HM+ alpha- and beta-crystallin increase, while gamma-crystallin decreases. The urea-soluble protein from clear lenses contains mainly of alpha beta chain, whereas in cataractous lenses the relative amounts of the 28 and 23ku polypeptides (the components of beta-crystallin) increased markedly. In cataractous lenses the relative amount of membrane intrinsic proteins decreases slightly and it has little statistical meaning.

Contribution of the B16 and B26 tyrosine residues to the biological activity of insulin

We report the synthesis and biological evaluation of five insulin analogues in which one or both of the B-chain tyrosine residues have been substituted. [B16 Phe]insulin and [B16 Trp]insulin display a very modest reduction in potency (c. 65%) relative to porcine insulin; [B26 Phe]insulin is less active (30-50%), and the doubly substituted [B16 Phe, B26 Phe]insulin displays still lower potency (c. 35%). The further substitution of Asp for B10 His in [B16 Phe, B26 Phe]insulin raises its activity to approximately twofold greater than natural insulin, an increase of approximately fivefold over the parent compound. We conclude that the bulk and/or aromaticity of the amino acid residue at position B16, but not its hydrogen-bonding capacity, contributes to the biological activity of the hormone. We further conclude that hydrogen-bonding capacity or special side-chain packing characteristics are required at the B26 position for insulin to display high biological activity.

Steric requirements at position B12 for high biological activity in insulin

The alpha-helix formed by the amino acid residues 9-19 of the B-chain of insulin is involved in the stabilization of its three-dimensional structure. We have shown that modification at positions B9, B10, B12, and B16 results in analogues possessing biological activities ranging from ca. 0.2% to ca. 500% relative to that of natural insulin. The lowest potency was displayed by [B12 Asn]insulin, in which the hydrophobic B12 Val residue was replaced by the hydrophilic Asn residue. We now report the synthesis of four insulin analogues in which hydrophobicity is retained, and only the spatial arrangement of atoms in the B12 region is altered. Substitution of B12 Val with alpha-aminoisobutyric acid (Aib), D-Ala, and Phe led to analogues possessing biological activities, in lipogenesis assays, of 8.5%, 2%, and 0.2%, respectively, relative to that of natural insulin. Inversion of the B11-B12 sequence, -Leu-Val-, led to an analogue displaying 3.3% activity. A synthetic B-chain in which the B11 Leu-B12 Val sequence was replaced by B11 Ala-B12 Ile was incapable of combining with the natural A-chain. We conclude that the Val residue in the B12 position in insulin fulfills special side-chain packing requirements involved in the stability of the structure of insulin. Even slight steric alteration at position B12 results in a distortion of the overall conformation of the B-chain which affects its ability to combine with the natural A-chain. This distortion is retained in the corresponding analogue, which is reflected in diminished biological potency.

Quasi-periodic motion in a hybrid optical bistable system with a short delay

The dynamical behavior of a hybrid optical bistable system with a short delay is calculated numerically in detail. The quasi-periodic motion and frequency locking of the system are observed experimentally.

Insulin analogues with modifications in the beta-turn of the B-chain

The beta-turn formed by the amino acid residues 20-23 of the B-chain of insulin has been implicated as an important structural feature of the molecule. In other biologically active peptides, stabilization of beta-turns has resulted in increases in activity. We have synthesized three insulin analogues containing modifications which would be expected to increase the stability of the beta-turn. In two analogues, we have substituted alpha-aminoisobutyric acid (Aib) for the Glu residue normally present in position B21 or for the Arg residue normally present in position B22; in a third compound, we have replaced the Glu residue with its D-isomer. Biological evaluation of these compounds showed that [B21 Aib]insulin displays a potency ca. one-fourth that of natural insulin, while [B22 Aib]insulin is less than 10% as potent. In contrast, [B21 D-Glu]insulin is equipotent with natural insulin. We conclude that the beta-turn region of the insulin molecule normally possesses considerable flexibility, which may be necessary for it to assume a conformation commensurate with high biological activity. If this is the case, [B21 D-Glu]insulin may exhibit a stabilized geometry similar to that of natural insulin when bound to the insulin receptor.

Effects of pre-exposures to a rotating optokinetic drum on adaptation to motion sickness

The purpose of this study was to investigate the effects of two different pre-exposure procedures on adaptation to motion sickness in a rotating circular vection drum. The 45 subjects were randomly divided into three groups. The control group only had a standard 16-min exposure to the drum rotating at 60 degrees/s with no pre-exposure. The incremental exposure group had two separated 4-min pre-exposure periods at 15 degrees/s and 30 degrees/s in the rotating drum immediately prior to the standard 16-min exposure period in the drum rotating at 60 degrees/s. The abrupt-exposure group had the same pre-exposure procedure except the pre-exposure drum rotation speed was 60 degrees/s and was followed by the same standard exposure periods. Subjective motion sickness reports and a measure of gastric myoelectric activity (electrogastrogram, EGG) were obtained during the standard 16-min drum rotation period in all three groups. The results showed that subjects in the incremental exposure group reported significantly fewer motion sickness symptoms during the standard 16-min rotation period than did the subjects in the abrupt exposure group and the control group. Subjects in the incremental exposure group also had less tachyarrhythmia, abnormal gastric myoelectric activity associated with nausea, during the 16-min rotation period than did the subjects in the control and abrupt exposure group. Incremental exposure to motion stimuli may be a useful method for training resistance to visually-induced motion sickness.

Superactive insulins

The substitution of aspartic acid for the naturally-occurring histidine residue in position B10 in human insulin results in an insulin analogue which displays an in vitro potency 4- to 5-fold greater than the parent compound. This substitution has been introduced into six insulin analogues which, before modification, display potencies ranging from less than 0.01-fold to 3-fold relative to natural insulin. In each case, the resulting aspartic acid-substituted analogue is substantially more potent than the parent compound. Thus, it is now possible to prepare "tailor-made" insulins with enhanced potency.