Construction of Unique Spiro[dibenzo[a,f]azulene-6,2'-indenes] via Unprecedented Annulation of ortho-C-H Bond of Benzylidene Group

The domino reaction of alkyl and aryl isocyanides with two molecules of 2-arylidene-1,3-indanediones in acetonitrile at 80 °C resulted in unique functionalized spiro[dibenzo[a,f]azulene-6,2'-indenes] in good yields, in which the two 2-arylidene-1,3-indanediones acted as different building blocks to construct the polycyclic system. More importantly, the unprecedented anticipation of the ortho-position of benzylidene group to form a novel dibenzo[a,f]azulene ring through a formal [5 + 2] cycloaddition process was first observed. On the other hand, DABCO-promoted reaction of the isocyanides with two molecules of 2-arylidene-1,3-indanediones in acetonitrile at 80 °C afforded functionalized spiro[cyclopenta[a]-indene-2,2'-indene] derivatives.

The efficacy of fat-free mass index and appendicular skeletal muscle mass index in cancer malnutrition: a propensity score match analysis

Background

Reduced muscle mass (RMM) is a phenotypic criterion for malnutrition; the appendicular skeletal muscle mass index (ASMI) and fat-free mass index (FFMI) are both applicable indicators in the global leadership initiative on malnutrition (GLIM) guideline. However, their sensitivity and prognostic effect remain unclear.

Methods

Clinical data of 2,477 patients with malignant tumors were collected. Multi-frequency bioelectrical impedance analysis was used to obtain ASMI and FFMI. RMM was confirmed by ASMI (< 7.0 kg/m² for men and < 5.7 kg/m² for women) or FFMI (< 17 kg/m² for men and < 15 kg/m² for women). Propensity score match analysis and logistic regression analysis were used to evaluate the efficacy of FFMI and ASMI in diagnosing severe malnutrition and multivariate Cox regression analysis to determine the efficacy of RMM in predicting survival.

Results

In total, 546 (22.0%) and 659 (26.6%) participants were diagnosed with RMM by ASMI (RMM.ASMI group) and FFMI (RMM.FFMI group); 375 cases overlapped. Body mass index (BMI), midarm circumference, triceps skinfold thickness, and maximum calf circumference were all significantly larger in the RMM.FFMI group for both sexes (P < 0.05). A 1:1 matched dataset constructed by propensity score match contained 810 cases. RMM.FFMI was an influential factor of severe malnutrition with HR = 3.033 (95% CI 2.068-4.449, P < 0.001), and RMM.ASMI was a predictive factor of overall survival (HR = 1.318, 95% CI 1.060-1.639, P = 0.013 in the RMM.ASMI subgroup, HR = 1.315, 95% CI 1.077-1.607, P = 0.007 in the RMM.FFMI subgroup).

Conclusion

In general, RMM indicates negative clinical outcomes; when defined by FFMI, it predicts nutritional status, and when defined by ASMI, it is related to poor survival in cancer patients.

Development of Formulas for Calculating L3 Skeletal Muscle Mass Index and Visceral Fat Area Based on Anthropometric Parameters

Background

The anthropometric index is not accurate but shows a great advantage in accessibility. Simple body composition formulas should be investigated before proceeding with the universal nutrition screening.

Materials and Methods

Clinical data of patients with a malignant tumor of the digestive system were collected. SliceOmatic 5.0 software (TOMOVISION, Canada) was used to analyze abdominal CT images and taken as references. A linear regression analysis was adopted to establish the formula for calculating skeletal muscle index (SMI) and visceral fat area (VFA). In addition, the relweights function was adopted to measure the contribution of each variable.

Results

In total, 344 patients were divided into the training set and 134 patients into the validation set. The selected formulas were SMI.pre = 0.540 × weight (kg) – 0.559 × height (cm) – 13.877 × sex (male = 1, female = 2) + 123.583, and VFA.pre = 5.146 × weight (kg) – 2.666 × height (cm) + 1.436 × age (year) + 134.096, of which the adjusted R² were 0.597 and 0.581, respectively. The “weight” explained more than 80% of R² in the prediction of VFA. In addition, “sex” occupied approximately 40% of R² in the prediction of SMI. The paired t-test showed no significant difference between the real measured indices and the predicting ones (p = 0.123 for SMI and p = 0.299 for VFA). The logistic regression analysis exhibited similar diagnostic efficacy of the real measured parameters and formulas.

Conclusion

The SMI and VFA formulas were developed through basic indices, such as weight, height, sex, and age. According to the contribution of each variable, weight should always be focused on preserving appropriate muscle and adipose tissue.

Treat-to-Target urate-lowering therapy in primary gout patients: A real-world retrospective study at a dedicated gout clinic in China

BACKGROUND

Gout is the most common inflammatory arthritis affecting 1.1% of the population in mainland China with a higher prevalence in coastal areas.

OBJECTIVE

The purpose of the study was to investigate the clinical outcomes following urate-lowering therapy (ULT) in a real-world group study of primary gout patients in China.

METHODS

Electronic medical records of all the gout patients (n= 1588) that visited the Clinical Medical Center of Gout of the Affiliated Hospital of Qingdao University from September 2016 to February 2018 were analyzed in this study. The patients were treated with a standard treat-to-target (T2T) ULT strategy according to the 2016 EULAR Guidelines. Clinical data were collected in the first visit and one-month (defined as the baseline of ULT), 7-month, and 13-month follow-ups were completed.

RESULTS

Amongst the patients in the study, 92.70% accepted ULT and 82.93% completed ULT for 3 months, 63.54% for 6 months, and 40.49% (n= 643) for 12 months. Further analysis of the 643 patients included the following data: the sUA level reduced at month 7 and reduced further at month 13. The gout flares, patient global pain visual analogue score, and health assessment questionnaire score improved at month 7 but did not improve further at month 13, and the index tophus size did not.

[Acupuncture based on meridian diagnosis for chronic atrophic gastritis]

OBJECTIVE

To compare the efficacy between acupoint selection of meridian diagnosis and regular acupoint selection for chronic atrophic gastritis (CAG).

METHODS

A total of 70 cases of CAG were randomly divided into an observation group (35 cases, 5 cases dropped off) and a control group (35 cases, 5 dropped off). In the observation group, according to the hand diagnosis of meridians and the results of 80-channels energy determinator, based on the principle of child-mother relation acupoint combination, the luo-connecting point and back-shu points were added for excess syndrome, and the yuan-primary point, front-mu points and he-sea point of foot meridians were added for deficiency syndrome; in addition, the acupoints of the eight extraordinary meridians were added based on the nature of acupoints. In the control group, Zhongwan (CV 12), Neiguan (PC 6), Zusanli (ST 36) and Gongsun (SP 4) were selected as the primary acupoints, and additional acupoints were added according to syndrome differentiation. The two groups were treated twice a week (Tuesday and Thursday, respectively), totally for 6 months. Six months after treatment, the follow-up was conducted. The clinical symptom score, gastroenteropathy patient reported outcomes (PRO) scale score before treatment, after treatment and during follow-up as well as the score of pathological changes of gastric mucosa before and after treatment were compared between the two groups.

RESULTS

After treatment and during follow-up, the clinical symptom scores and gastroenteropathy PRO scale scores were decreased in the two groups (P<0.01, P<0.001); at the follow-up, the gastroenteropathy PRO scale score in the observation group was lower than that in the control group (P<0.01). After treatment, the scores of pathological changes of gastric mucosa in the two groups were decreased (P<0.01), and the score in the observation group was lower than that in the control group (P<0.05).

CONCLUSION

The acupoint selection of meridian diagnosis is superior to regular acupoint selection for CAG, which has better efficacy, more significant improvement on gastric mucosa pathology, and more stable long-term effect.

[Analysis of the clinical effect on post-stroke shoulder hand syndrome stage Ⅰ treated with the along-meridian trochar acupuncture therapy]

OBJECTIVE

To compare the differences in the clinical effect on post-stroke shoulder hand syndrome (SHS) stage Ⅰ between the along-meridian trochar acupuncture therapy and the routine acupuncture therapy with filiform needles.

METHODS

A total of 80 patients with post-stroke SHS stage I were divided into a treatment group (41 cases) and a control group (39 cases) according to the random number table. In the control group, the common filiform needles were used to stimulate Jianyu (LI15), Jianliao (TE14), Jianzhen (SI9), Jianzhongshu (SI15), Jianwaishu (SI14), 5 times a week, 3 weeks as 1 course. In the treatment group, along-meridian trochar acupuncture therapy was applied, 3 times a week, 3 weeks as 1 course. The patients in both groups were all treated with basic medications and routine rehabilitation training. Pain degree, edema degree, upper limb motor function and activity of daily living were observed in the two groups before the treatment, at the end of the treatment and in follow-up. At the end of treatment and in follow-up, the therapeutic effect was evaluated respectively in the patients of the two groups.

RESULTS

Compared with the values before treatment, the VAS score of the upper limb was reduced obviously (P< 0.001), the score of the upper limb motor function and Barthel index were increased obviously (P<0.001, P<0.05) in the patients of the two groups, the score of edema degree of the affected limb was reduced after treatment in the patients of the treatment group (P<0.001). Compared with the control group, VAS score of the upper limb and the score of edema degree of the affected limb were obviously lower (P<0.001), and the score of the upper limb motor function and Barthel index were obviously higher in the treatment group (P<0.001). The total effective rate was 66.7% (26/39) after treatment and was 74.4% (29/39) in follow-up in the treatment group and they were 20.5% (8/39) and 28.2% (11/39) respectively in the control group. The total effective rates after treatment and in follow-up in the treatment group were all obviously higher than those in the control group respectively (P<0.001).

CONCLUSION

The along-meridian trochar acupuncture therapy remarkably relieves pain and edema and improves the upper limb motor function and the activity of daily living in the patients with post-stroke shoulder hand syndrome and its clinical therapeutic effect is definite.

Synergistic nourishing 'Yin' effect of iridoid and phenylpropanoid glycosides from Radix Scrophulariae in vivo and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Radix Scrophulariae (RS), is a renowned traditional Chinese medicine used as nourishing 'Yin'. The iridoid glycosides (IG) and phenylpropanoid glycosides (PG) are main chemical constituents in RS. However, there had been no pharmacological experiment studies of synergy between IG and PG. Due to the constituents interactions, exploring their synergy profile is of great important for explaining the essence of nourishing 'Yin' efficacy of RS.

AIM OF STUDY

The present study was undertaken to evaluate synergistic nourishing 'Yin' effect of IG and PG from RS in vivo and in vitro through their immunoregulation and antioxidant activities.

MATERIALS AND METHODS

In this study, IG and PG fractions in RS were isolated and identified by High Performance Liquid Chromatography coupled with tandem quadrupole time-of-flight Mass Spectrometry (HPLC-Q-TOF-MS). The synergistic nourishing 'Yin' effect of two fractions were investigated in vivo and in vitro with thyroxine-induced 'Yin' deficiency (YD) mice model and primary splenic lymphocyte, respectively. The exterior syndrome signs and serologic and cellular biomarkers changes were detected. Then, the synergistic coefficient (SC) of IG and PG on every pharmacodynamics index were calculated by Webb method.

RESULTS

Compared with model and mono-therapy group (IG or PG group), IG combined with PG group significantly ameliorated YD by exerting immunoregulation and antioxidant effects. Based on the SC, IG and PG possessed a synergistic effect on heart rate, average speed, upright times, spleen index, LPO, SOD, IL-6, Na⁺-K⁺-ATP enzyme in vivo, and cAMP/cGMP, IFN-γ/IL-10, and MDA in vitro with SC > 1.

CONCLUSIONS

The nourishing 'Yin' benefits were clearly produced when IG and PG were used in combination, which provided the scientific evidence of multiple-components and multiple-approach synergistic effect of Chinese traditional herbal medicine to control and management of diseases.

Reconstruction of Vehicle-pedestrian Collision Road Traffic Accidents Based on PC-Crash Software

Abstract

Objective To discuss the application value of vehicle-pedestrian collision road traffic accidents reconstruction based on PC-Crash software in forensic identification. Methods A case of vehicle-pedestrian collision was chosen based on a tachograph, then PC-Crash software was applied to construct a vehicle-pedestrian collision model, and reconstruct the vehicle-pedestrian collision road traffic accident. Finally, the process of vehicle-pedestrian collision was reproduced. Results In accident reconstruction, when the car speed was lower than 50km/h, the landing point of the pedestrian after collision was in the front of the car. When the car speed was higher than 50 km/h, after collision, the pedestrian flipped towards the car roof and landed behind the car. With the increase of vehicle speed, throwing distance of the pedestrian increased continuously. When the vehicle collision speed reached 60 km/h, the experimental results in this case were basically consistent with the actual situation of the case. Head acceleration of the pedestrian was at the maximum （1 655.70 m/s²） at 0.080 s. Chest acceleration of the pedestrian increased from 597.63 m/s² to the peak 675.52 m/s² at 0.055-0.060 s. Tibia acceleration of the pedestrian increased from 759.26 m/s² to the first peak 1 367.06 m/s², then reached the maximum speed （1 718.19 m/s²） at 1.225 s. Conclusion The process of vehicle-pedestrian collision road traffic accidents can be reconstructed based on PC-Crash software under a situation of limited conditions, and can further clarify the speed of the vehicle, the location and degree of human body injury as well as the mechanism of damage of the pedestrian in the accident. Therefore, PC-Crash software has a certain practical value in forensic identification of road traffic accidents.

[Research Progress of Traffic Accident Reconstruction Technology Based on PC-Crash Software]

With the development of the computer simulation technology and the digital simulation technology, the traditional calculation method has been gradually replaced by the digital method to deal the road traffic accident scene and analyse the process. The PC-Crash software simulation system can reconstruct the traffic accidents within 32 vehicles, and the accuracy of reconstruction has been fully verified, which is widely used by the transport police department and the accreditation agency. In this paper, the research of road traffic accident reconstruction using PC-Crash software is reviewed, and the application of road traffic accident reconstruction technology based on PC-Crash software and some existing problems in forensic practice are discussed, which provides reference for the research and identification of road traffic accident simulation and reconstruction and theoretical basis for accident treatment.

[Research Progress of Yunnan Unexplained Sudden Death]

Yunnan unexplained sudden death （YUSD） has obvious spatial and temporal aggregations. With the features of sudden onset and rapid death, its causes remain unclear. However, the onset of YUSD is related to the geological and climatic conditions in specific range of altitude of incidence area, which is also influenced by the existed susceptibility gene loci or several multiple mutations in SNP loci, long-term fatigue, low dietary nutrition, trace element deficiency, poor living condition and hygienic habit, and infection by etiologic microorganism or virus among the residents live in the incidence area of YUSD. Under the continuous influence of factors above, the crowd of incidence area finally occurred unexplained sudden death that prominently shown by myocardial injury. Improvements of public health administration, living conditions, villagers' health, living habits and enhancement of indicator measurement of myocardial enzyme and electrocardiogram for the residents in the incidence area of YUSD are effective measures for prevention of YUSD. Timely identification of cause of death and in-depth genetic research are important ways to explore the causes of YUSD, enhance the effectiveness of treatment and reduce the death rate.

Multiple effects of probiotics on different types of diabetes: a systematic review and meta-analysis of randomized, placebo-controlled trials

BACKGROUND

A systematic review and meta-analysis was designed to evaluate the effect of probiotics on diabetes and its associated risk factors.

METHODS

We systematically searched the Cochrane Library, PubMed, EMBASE and Web of Science to June 2016. We also hand-searched the citation lists of included studies and previously identified systematic reviews to identify further relevant trials. Our primary outcome variables included glucose, glycated hemoglobin (HbA1c) and insulin. The pooled standardized mean difference was used to compare the effect between the probiotics and controlled groups, and the pooled standardized mean difference effect size with a 95% confidence interval (CI) was estimated using a random-effect model. Heterogeneity was assessed with Cochran's Q and Higgins I2 tests. Two reviewers assessed trial quality and extracted data independently. The analysis and bias for each included study was performed and assessed using Review Manager 5.2.

RESULTS

Eighteen randomized, placebo-controlled studies (n=1056 participants, 527 consuming probiotics, 529 not consuming probiotics) were included for analysis. Comparing the probiotics groups with the control groups, there were statistically significant pooled standardized mean differences on the reduction of glucose (-0.61, 95% CI -0.98, -0.24; p=0.001), insulin (-0.49, 95% CI -0.93, -0.04; p=0.03) and HbA1c (-0.39, 95% CI -0.60, -0.19%; p=0.0001). Subgroup analysis also indicated statistical significance on the reduction of low-density lipoprotein cholesterol (LDL-C) in non-type 2 diabetes (non-T2DM) mellitus patients with diabetes, for the pooled standardized mean difference was -0.29 (95% CI -0.54, -0.04; p=0.02).

CONCLUSIONS

Probiotics may have beneficial effects on the reduction of glucose, insulin and HbA1c for diabetes, especially for T2DM mellitus patients.

[Pollution Characteristics of Antibiotic Resistant Bacteria from Atmospheric Environment of Animal Feeding Operations]

Animal feeding operations is considered as a source of airborne human pathogens and antibiotics genes. In this study, we investigated the concentration, size distribution and aerodynamic diameter of airborne bacteria, tetracycline resistant bacteria and erythromycin resistant bacteria from 22 animal feeding operations in three districts of Beijing. The results indicated that the highest and lowest concentrations of these three types of bioaerosol were detected in pig and cow house, respectively. The concentration of airborne bacteria was higher in layer house, whereas concentration of antibiotic resistant bacteria was higher in broiler house. Tetracycline and erythromycin resistant bacteria were detected from the atmospheric environment from out door of layer and broiler house with the percentages of 8.81%, 15.89% and 23.19%, 36.53%, respectively. The size distribution and aerodynamic diameter varied from inside and outside of pig, cow, and layer and broiler house. Most of tetracycline resistant bacteria and erythromycin resistant bacteria from current four types of animal feeding operations mainly deposited in pharynx, larynx and bronchus of respiratory system. This study would offer the base data for evaluating the detriment of bioaerosol from animal feeding operations to the worker and environment.

(E)-1-[2-Hy-droxy-4,6-bis-(meth-oxy-meth-oxy)phen-yl]-3-phenyl-prop-2-en-1-one

The title compound, C₁₉H₂₀O₆, consists of a tetra­substituted benzene ring with one substituent being an α,β-unsaturated cinnamoyl group, which forms an extended conjugated system in the mol­ecule. In addition, two meth­oxy­meth­oxy and one hy­droxy group are bonded to the central benzene ring. The dihedral angle between eh rings is 10.22 (10)°. An intra­molecular hydrogen bond is observed between the hy­droxy group and the carbonyl O atom. One of the meth­oxy­meth­oxy substituents is conformationally disordered over two sets of sites with site-occupation factors of 0.831 (3) and 0.169 (3).

[Effect of preventive acupuncture and moxibustion at "Guanyuan" (CV 4) on the expression of HSP 70 and HSP 70 mRNA in spleen and the contents of serum IL-2, TNF-alpha in menopausal rats]

OBJECTIVE

To observe the influence of preventive acupuncture (PA) and preventive moxibustion (PM) at "Guanyuan" (CV 4) on the immune function in natural climacteric rats.

METHODS

A total of 160 female SD rats were randomized into control, PA and PM groups, the former one group was further divided into 10 month (mon), 12 mon, 14 mon and 16 mon subgroups, and the later two groups were further divided into 12 mon, 14 mon and 16 mon subgroups, with 16 rats in each. In addition, other 16 female SD rats aged 3.5 mon were used as the young control (YC) group. "Guanyuan" (CV 4) was punctured with an acupuncture needle and the needle was retained for 20 min, or given with one ignited moxa-cone from the age of 10 mon on. The treatment was conducted twice every week, 8 weeks altogether. The expression of HSP 70 and HSP 70 mRNA of the spleen tissue was detected by using immunohistochemistry and in situ hybridization respectively, and serum IL-2 and TNF-alpha contents were assayed by using radio-immunoassay.

RESULTS

In comparison with YC group, 1) the expression of spleen HSP 70 and HSP 70 mRNA increased significantly in 10 mon control (mon-C), 12 mon-PM and 12 mon-PA groups, and 14 mon-PA group (only HSP 70 mRNA) (P < 0.05, P < 0.01); 2) HSP 70 expression decreased remarkably in 14 mon-C, 16 mon-C and 16 mon-PA groups (P < 0.05, P < 0.01); 3) IL-2 contents decreased evidently in 12 mon-C and 14 mon-C groups, and TNF-alpha contents increased obviously in 12 mon-PM, 12 mon-PA and 16 mon-C groups (P < 0.05). In comparison with the corresponding same age control groups, HSP 70 and HSP 70 mRNA expression increased significantly in 12 mon-PM and 12 mon-PA groups, 14 mon-PM and 16 mon-PM (HSP 70 only), 14 mon-PA (HSP 70 mRNA only) groups (P < 0.05, P < 0.01); IL-2 level of 12 mon-PM group, and TNF-alpha contents of 12 mon-PM and 12 mon-PA groups increased markedly (P < 0.05, P < 0.01). No significant differences were found between PM and PA groups in most different age groups (P > 0.05).

CONCLUSION

Both preventive acupuncture and preventive moxibustion can upregulate the expression of spleen HSP 70 and HSP 70 mRNA and serum IL-2 and TNF-alpha levels, which may contribute to their effects in enhancing the immune function in menopausal rats.

The role of orphan nuclear receptor in thymocyte differentiation and lymphoid organ development

T lymphocytes differentiate in the thymus through several phenotypically distinct stages that are tightly regulated by multiple nuclear transcription factors. Immature CD4+CD8+ double positive (DP) thymocytes make up a majority of the population in the thymus, and exhibit several phenotypic features distinct from mature T cells. DP thymocytes express only about 10% of surface TCR that are found on mature T cells and do not proliferate and produce IL-2 in response to stimulation. Several critical events of T lymphocyte maturation such as TCRalpha gene recombination, positive and negative selection, and CD4/CD8 lineage commitment occur around the DP stage. Recent studies from our group and others on the orphan nuclear receptor RORgamma and its thymus-specific isoform RORgammat support a critical role for this nuclear receptor in the regulation of DP thymocyte function. In addition, RORgamma is required for the development of lymph nodes and Peyer's patches.

Down-regulation of the orphan nuclear receptor ROR gamma t is essential for T lymphocyte maturation

Thymocyte development is a tightly regulated process. CD4+CD8+ double-positive (DP) immature thymocytes exhibit distinct phenotypic features from mature T cells; they express only 10% of surface TCR that are found on mature T cells and do not proliferate and produce IL-2 in response to stimulation. In this report we show that transgenic expression of the orphan nuclear receptor ROR gamma t in mature T cells down-regulates their surface TCR expression. The ROR gamma t transgene inhibits IL-2 production by mature T cells, and this inhibition may be partially due to the inhibitory effect of ROR gamma t on c-Rel transcription. Furthermore, ectopic expression of ROR gamma t inhibits the proliferation of mature and immature T cells. These results, together with its predominant expression in DP thymocytes, suggest that ROR gamma t controls these distinct phenotypic features of DP thymocytes. Our data suggest that down-regulation of ROR gamma t expression in thymocytes is essential for their maturation.

Multiple gamma c-dependent cytokines regulate T-cell development

Mutations in the common gamma chain (gamma c) of cytokine receptors account for human X-linked severe combined immunodeficiency disease. gamma c contributes to ligand binding and signaling as a component of five cytokine receptors: interleukin-2-receptor (IL-2R), IL-4R, IL-7R, IL-9R and IL-15R. Here, Thomas Malek and colleagues discuss the contribution of individual gamma c-dependent cytokines in both conventional and intraepithelial T-cell development.

The structure and function of gamma c-dependent cytokines and receptors: regulation of T lymphocyte development and homeostasis

Five cytokines, IL-2, IL-4, IL-7, IL-9, and IL-15, form one group that is characterized by utilizing the common gamma chain (gamma c) as a receptor subunit. Examination of the phenotype of various cytokine or cytokine receptor "knockout" mice demonstrates that these cytokines are critical for normal lymphocyte development and subsequent functional activity of the peripheral immune compartment. This review summarizes the structural and functional properties of each of these five cytokines and their receptors, including the known redundant pathways for each cytokine or receptor. The contribution of these cytokines and receptors will then be considered in detail with respect to regulation of T lymphocyte development and homeostasis of the peripheral T cell compartment.

Monoclonal antibodies to the common gamma-chain as cytokine receptor antagonists in vivo: effect on intrathymic and intestinal intraepithelial T lymphocyte development

Mice lacking a functional gamma c subunit of cytokine receptors exhibit profound defects in the development of multiple lymphoid lineages. To investigate the role of gamma c-dependent cytokines in T cell development, the phenotype of developing T cells was compared in interleukin (IL)-7Ralpha-deficient mice and anti-gamma c mAb-treated chimeric mice reconstituted with adult bone marrow cells or subsets of pro-T cells. These studies indicate that gamma c contributes to T cell development at multiple stages of pro-T cell maturation and that IL-7/IL-7R is the primary cytokine for thymic-dependent T cell development. However, our data also implicate other gamma c-dependent cytokines during thymic T cell development. By contrast, substantial intestinal intraepithelial lymphocytes (IEL) development was observed in the intestinal intraepithelium in both types of mice. Analysis of IL-7Ralpha-deficient mice indicates that the IL-7/IL-7R system is critical only for the development of TCR gammadelta+ IEL. However, the inhibitory activity of the anti-deltac mAb in the chimeric mouse model suggests that additional gamma cutilizing cytokines regulate the development of the remaining subsets of IEL.

Rotavirus RNA polymerase requires the core shell protein to synthesize the double-stranded RNA genome

Rotavirus cores contain the double-stranded RNA (dsRNA) genome, RNA polymerase VP1, and guanylyltransferase VP3 and are enclosed within a lattice formed by the RNA-binding protein VP2. Analysis of baculovirus-expressed core-like particles (CLPs) has shown that VP1 and VP2 assemble into the simplest core-like structures with replicase activity and that VP1, but not VP3, is essential for replicase activity. To further define the role of VP1 and VP2 in the synthesis of dsRNA from viral mRNA, recombinant baculoviruses containing gene 1 (rBVg1) and gene 2 (rBVg2) of SA11 rotavirus were generated and used to express recombinant VP1 (rVP1) and rVP2, respectively. After purification, the proteins were assayed individually and together for the ability to catalyze the synthesis of dsRNA in a cell-free replication system. The results showed that dsRNA was synthesized only in assays containing rVP1 and rVP2, thus establishing that both proteins are essential for replicase activity. Even in assays containing a primer-linked mRNA template, neither rVP1 nor rVP2 alone directed RNA synthesis. Characterization of the cis-acting replication signals in mRNA recognized by the replicase of rVP1 and rVP2 showed that they were the same as those recognized by the replicase of virion-derived cores, thus excluding a role for VP3 in recognition of the mRNA template by the replicase. Analysis of RNA-protein interactions indicated that the mRNA template binds strongly to VP2 in replicase assays but that the majority of the dsRNA product neither is packaged nor stably associates with VP2. The results of replicase assays performed with mutant VP2 containing a deletion in its RNA-binding domain suggests that the essential role for VP2 in replication is linked to the protein's ability to bind the mRNA template for minus-strand synthesis.

The common gamma-chain of cytokine receptors regulates intrathymic T cell development at multiple stages

Signaling through the common gamma chain (gamma c), a subunit of the receptors for IL-2, -4, -7, -9, and -15, is critical for lymphocyte development, with the IL-7/IL-7R representing one important interaction. To investigate the stages of intrathymic T cell development that are dependent on gamma c and to determine whether gamma c controls T cell development solely as a component of the IL-7R, intrathymic T cell development was compared in IL-7R alpha-deficient mice and anti-gamma c-treated chimeric mice reconstituted with bone marrow and purified pro-T cells. In the presence of anti-gamma c, each of four phenotypically distinguishable stages of CD4- CD8- thymocytes failed to reconstitute T cell development, suggesting that each of these subsets of pro-T cells required gamma c for their differentiation and/or growth. Reconstitution of anti-gamma c-treated chimeric mice with bone marrow from IL-7R alpha-deficient mice indicated that IL-7R only partially contributed to intrathymic T cell development. Furthermore, when compared with IL-7R-deficient mice, anti-gamma c chimeric and gamma c-deficient mice exhibited a distinct phenotypic pattern of pro-T cell development. Collectively, these results indicate that several gamma c-sharing cytokines may contribute to T cell development in the thymus and suggest that one of these cytokines may be novel.

The common gamma-chain of cytokine receptors regulates intrathymic T cell development at multiple stages

Signaling through the common gamma chain (gamma c), a subunit of the receptors for IL-2, -4, -7, -9, and -15, is critical for lymphocyte development, with the IL-7/IL-7R representing one important interaction. To investigate the stages of intrathymic T cell development that are dependent on gamma c and to determine whether gamma c controls T cell development solely as a component of the IL-7R, intrathymic T cell development was compared in IL-7R alpha-deficient mice and anti-gamma c-treated chimeric mice reconstituted with bone marrow and purified pro-T cells. In the presence of anti-gamma c, each of four phenotypically distinguishable stages of CD4- CD8- thymocytes failed to reconstitute T cell development, suggesting that each of these subsets of pro-T cells required gamma c for their differentiation and/or growth. Reconstitution of anti-gamma c-treated chimeric mice with bone marrow from IL-7R alpha-deficient mice indicated that IL-7R only partially contributed to intrathymic T cell development. Furthermore, when compared with IL-7R-deficient mice, anti-gamma c chimeric and gamma c-deficient mice exhibited a distinct phenotypic pattern of pro-T cell development. Collectively, these results indicate that several gamma c-sharing cytokines may contribute to T cell development in the thymus and suggest that one of these cytokines may be novel.

Interleukin-7 receptor alpha is essential for the development of gamma delta + T cells, but not natural killer cells

Mice that lack a functional gamma c subunit of the receptors for interleukin (IL)-2, IL-4, IL-7, IL-9, and IL-15 display profound defects in lymphoid development. The IL-7/IL-7R system represents a critical interaction for conventional T and B cell development. In this report, the role of IL-7R alpha in the development of lymphoid lineages other than conventional T and B cells was examined. We demonstrate that gamma delta + T cells were absent in IL-7R alpha-deficient mice, whereas the development and function of natural killer cells were normal. Thus, IL-7R alpha function is required for the development of gamma delta + T cells but not natural killer cells.

Detection of replicative form of HCV RNA in peripheral blood leukocytes and its clinical significance

Nested RT-PCR, done by using degenerated primer pair, was used to detect hepatitis C virus RNA (HCV RNA) in serum, plasma, liver and peripheral blood mononuclear cells (PBMC) of 30 patients with acute and chronic posttransfusion hepatitis C and 7 asymptomatic anti-HCV positive subjects. The results showed that the percentages of both the plus and minus strands of HCV RNA in PBMC of the patients with chronic hepatitis C was significantly higher than that with acute hepatitis C and asymptomatic anti-HCV positive subjects (P < 0.05-0.001). In 17 patients who were subjected to biopsy, the positive rate of the both strands of HCV RNA in PBMC of the patients with AH was lower than that of CAH (P < 0.05). In serum and plasma of all 37 cases, the minus strand of HCV RNA was not detected. Both plus and minus strands in liver of one patient with AH were positive, but the minus strand in PBMC negative. In 6 patients with CAH whose both strands in liver were positive, both strands in PBMC in 5 patients were also found. The present data confirmed that PBMC of the patients with hepatitis C were infected by HCV and the longer the infection time, the bigger the possibility of PBMC infection by HCV. The patients with active liver disease (CAH) had higher positive rate of minus strands of HCV RNA in PBMC. The results suggested that HCV may not only infect PBMC but also replicate in PBMC, and that the occurrence of minus strand of HCV RNA is associated with activity of liver disease.

The IL-2 receptor gamma c chain does not function as a subunit shared by the IL-4 and IL-13 receptors. Implication for the structure of the IL-4 receptor

The IL-2 receptor (IL-2R) gamma c subunit is also a component of the receptors for IL-4, IL-7, IL-9, and IL-15. The IL-4R and IL-13R appear to share a common subunit, and gamma c was proposed to be this shared subunit. In this study, we have assessed the relative contribution of gamma c to the mouse IL-4R and IL-13R. The MC/9 mast cell line constitutively expresses gamma c and proliferates to IL-4 and IL-13, but only the response to IL-4 was blocked by anti-gamma c mAbs. After transfection of the IL-4- and IL-13-responsive gamma c-negative B9 plasmacytoma with full length (m gamma) or cytoplasmic-tailless gamma c cDNA (m gamma t), only the proliferative response to IL-4 was affected by the surface expression of these gamma c molecules. The inability of m gamma or m gamma t expression to affect IL-13-induced proliferation by B9 indicates that gamma c does not obviously contribute to the IL-13R and does not function as the shared subunit of the IL-4R and IL-13R. This study suggests that there are two distinct IL-4R, one of which is independent of gamma c.

The IL-2 receptor gamma c chain does not function as a subunit shared by the IL-4 and IL-13 receptors. Implication for the structure of the IL-4 receptor

The IL-2 receptor (IL-2R) gamma c subunit is also a component of the receptors for IL-4, IL-7, IL-9, and IL-15. The IL-4R and IL-13R appear to share a common subunit, and gamma c was proposed to be this shared subunit. In this study, we have assessed the relative contribution of gamma c to the mouse IL-4R and IL-13R. The MC/9 mast cell line constitutively expresses gamma c and proliferates to IL-4 and IL-13, but only the response to IL-4 was blocked by anti-gamma c mAbs. After transfection of the IL-4- and IL-13-responsive gamma c-negative B9 plasmacytoma with full length (m gamma) or cytoplasmic-tailless gamma c cDNA (m gamma t), only the proliferative response to IL-4 was affected by the surface expression of these gamma c molecules. The inability of m gamma or m gamma t expression to affect IL-13-induced proliferation by B9 indicates that gamma c does not obviously contribute to the IL-13R and does not function as the shared subunit of the IL-4R and IL-13R. This study suggests that there are two distinct IL-4R, one of which is independent of gamma c.

Blockade of T- and B-lymphocyte development by antibody to the gamma c subunit of the receptors for interleukins 2, 4, and 7

Cytokines are important regulators of hematopoesis. Mutations in gamma c, which is a subunit shared by the receptors for interleukin (IL) 2, IL-4, and IL-7, have been causally associated with human X chromosome-linked severe combined immunodeficiency disease. This finding indicates a mandatory role for cytokine receptor signaling at one or more stages of lymphocyte development. To evaluate the cellular level at which gamma c is critical for lymphopoiesis, the effect of monoclonal antibodies to gamma c on the capacity of syngeneic bone marrow cells to reconstitute the hematopoietic compartment of lethally irradiated recipient mice was examined. We show that monoclonal antibody to gamma c blocked lymphocyte development at or before the appearance of pro-B cells and prior to or at the seeding of the thymus by precursor cells while erythromyeloid cell development was normal. These results suggest that one level of lymphocyte development that requires gamma c is a point in hematopoietic cell differentiation near the divergence of lymphopoiesis and erythromyelopoesis.

Biochemical identity and characterization of the mouse interleukin-2 receptor beta and gamma c subunits

Although the mouse IL-2 receptor (IL-2R) beta and gamma c subunits have been identified by molecular cloning, the biochemical identity of these subunits has not yet been established. In the present study, the mouse IL-2R was biochemically characterized from cell lines expressing normal and aberrant IL-2R. Using novel monoclonal antibodies specific for the beta or gamma c subunits, we established that the M(r) of the beta chain is 90,000-100,000 and that of the gamma c subunit is 75,000-80,000. Analysis of transfected EL4 cells that expressed alpha, gamma c, and truncated beta subunits or mutant EL4 cells, which selectively lacked cell surface gamma c, revealed that no other material migrated to a position on SDS-PAGE characteristic of IL-2/IL-2R beta and IL-2/IL-2R gamma c cross-linked complexes, respectively. Thus, the beta and gamma c subunits appear to be the sole IL-2R constituents of these IL-2 cross-linked complexes. The IL-2/IL-2R gamma c, but not the IL-2/IL-2R beta, complex exhibited enhanced mobility after SDS-polyacrylamide gel electrophoresis under nonreducing conditions, suggesting a more compact structure for gamma c as a result of intrachain disulfide bonds. The primary posttranslational modification of the mouse beta and gamma c subunits is N-linked glycosylation. These biochemical studies reconcile past uncertainties concerning the subunit composition of the mouse IL-2R and are consistent with a model of the IL-2R containing only three subunits.

Expression and function of the gamma c subunit of the IL-2, IL-4, and IL-7 receptors. Distinct interaction of gamma c in the IL-4 receptor

IL-2R, IL-4R, and IL-7R share a common subunit referred to as gamma c and the IL-13R has been proposed to contain gamma c as a subunit. In this report we have used two novel mAbs (3E12 and 4G3) to distinct epitopes of mouse gamma c to determine its lymphoid cell distribution and to examine whether gamma c uses similar epitopes to interact with different cytokines and cytokine receptors. FACS analysis revealed that gamma c is expressed in most lymphocytes, myeloid cells, embryonic thymocytes, and lymphoid cell lines. Results from radiolabeled ligand binding studies, biochemical analysis of ligand-receptor cross-linked complexes, and cytokine bioassays indicate that the epitope defined by mAb 4G3 closely defines the IL-7 binding region of gamma c and overlaps the IL-2 binding region of gamma c. These studies also indicate that gamma c interacts with IL-4 in the context of the IL-4R in a manner that is distinct from its role in the IL-2R and IL-7R and suggest that the 3E12 epitope defines a region of gamma c that intimately interacts with the IL-4R. The B9 plasmacytoma, which proliferates in response to IL-4 and IL-13, was shown to not express gamma c. Thus, at least in some circumstances, gamma c is dispensable for signaling via the IL-4R and is not a required subunit of the IL-13R.

Expression and function of the gamma c subunit of the IL-2, IL-4, and IL-7 receptors. Distinct interaction of gamma c in the IL-4 receptor

IL-2R, IL-4R, and IL-7R share a common subunit referred to as gamma c and the IL-13R has been proposed to contain gamma c as a subunit. In this report we have used two novel mAbs (3E12 and 4G3) to distinct epitopes of mouse gamma c to determine its lymphoid cell distribution and to examine whether gamma c uses similar epitopes to interact with different cytokines and cytokine receptors. FACS analysis revealed that gamma c is expressed in most lymphocytes, myeloid cells, embryonic thymocytes, and lymphoid cell lines. Results from radiolabeled ligand binding studies, biochemical analysis of ligand-receptor cross-linked complexes, and cytokine bioassays indicate that the epitope defined by mAb 4G3 closely defines the IL-7 binding region of gamma c and overlaps the IL-2 binding region of gamma c. These studies also indicate that gamma c interacts with IL-4 in the context of the IL-4R in a manner that is distinct from its role in the IL-2R and IL-7R and suggest that the 3E12 epitope defines a region of gamma c that intimately interacts with the IL-4R. The B9 plasmacytoma, which proliferates in response to IL-4 and IL-13, was shown to not express gamma c. Thus, at least in some circumstances, gamma c is dispensable for signaling via the IL-4R and is not a required subunit of the IL-13R.

[Determination of alkaloids and comparison of the acute toxicity of differently processed products of the seeds of Strychnos nux-vomica L]

This paper deals with the extraction, determination and identification of the alkaloids in differently processed products of the seeds of Strychnos nux-vomica. The relationship between processing methods and toxicitys is discussed according to the comparison of acute toxicity.

A research on DLA-DRB1 genotyping by PCR-RFLP. I. To select a appropriate oligonucleotide primer pair

In order to study the DLA (Dog Leucocyte Antigen) class II region we utilized the polymerase chain reaction based restriction fragment length polymorphism (PCR-RFLP) method, which has been reported previously as an efficient and simple technique for accurate definition of the HLA class II alleles. To search for a appropriate primer pair a series of amplifications with 4 different primer pairs DLA-DR-SP/Stop, DLA-DR-SP/P3, HLA-DRB-GH46/50 and HLA-DRB-AMP-A/B were provided. Only one satisfactory amplification was obtained with the primer pair HLA-DRB-AMP-A/B. The analogous sequences of the primer pair are found in the sequence of HLA-DRB-cDNA. The amplification region of the primer pair includes also the three hypervariable regions (HVR) in the sequence of DLA-DRB cDNA. Southern blot hybridization analysis confirmed the specificity of the primer pair HLA-DRB-AMP-A/B. The results of Hae III and Hinfl digestion show high polymorphism in DLA-D region and allele specific polymorphic patterns. Therefore, it is suggested that the primer pair HLA-DRB-AMP-A/B is at present the only available and usefull primer pair in PCR-RFLP study of DLA-DRB1 gene.

Researches on DLA-DRB1 genotyping by PCR-RFLP. II. A study of serology and cellularly defined DLA haplotypes and their segregation

The polymerase chain reaction based restriction fragment length polymorphism (PCR-RFLP) method was used to study DLA class II gene in dogs. Genomic DNA from 11 DLA homozygous reference dogs representing 8 different haplotypes and 2 families with a total of 16 animals were amplified by the oligonucleotide primer pair (HLA-DRB-AMP-A/B) cross-hybridizing HLA-DRB specific and fit for the amplification of DLA-DRB1 gene. The corresponding amplified DNA products were 235 base pairs. Amplified DNA was digested by 32 different restriction endonucleases, which could recognize allelic variations within DLA-DRB. After digesting only with Hae III, Hha I, Hinf I, Rsa I and Sau96 I high polymorphism was revealed respectively and 9 distinct RFLP pattern were shown, which could be correlate to the DLA haplotypes studied. The 8 cellular established DLA-D specificities present in the reference panel were defined unequivocally by PCR-RFLP and correlated with DLA-Dw5 and Dw6 two subtypes. The segregation pattern of four different DLA-DRB types could be demonstrated in two families. Based on these data we conclude that PCR-RFLP typing utilizing the above mentioned primer pair and endonucleases is a valuable tool to define DLA class II types in the dog.

Asp96 deprotonation and transmembrane alpha-helical structural changes in bacteriorhodopsin

The M-->N transition in the photocycle of bacteriorhodopsin involves the transfer of a proton from Asp96 to the retinylidene Schiff base, possibly through a network of hydrogen-bonded amino acid residues and water molecules (Rothschild, K. J., He, Y. W., Sonar, S., Marti, T., and Khorana, H. G. (1992) J. Biol. Chem. 267, 1615-1622). A conformational change of the protein backbone is also observed during this transition. In this work, we have investigated the effects of replacing the residue Thr46, which might be part of this chain, with an aspartic acid. Both Fourier transform infrared and resonance Raman spectroscopy show that the chromophore structure of this mutant (T46D) is normal. However, N formation is accelerated and N decay is significantly slowed compared to wild-type bacteriorhodopsin. This effect causes the N intermediate to accumulate under steady-state illumination thereby facilitating spectroscopic studies under normal pH conditions. Fourier transform infrared difference spectroscopy reveals that like native bacteriorhodopsin, N formation in T46D involves deprotonation of Asp96, reprotonation of the Schiff base, and a change in the backbone secondary structure. However, in contrast to bacteriorhodopsin, bands assigned to the C = O stretch mode of the carboxylic acid group of Asp96 are upshifted by 10 cm-1 reflecting a change in the Asp96 environment and a drop in its effective pKa throughout the photocycle. This change in the pKa can directly account for changes in the photocycle kinetics and indicates that Asp96 deprotonation/protonation are the rate limiting steps in the formation and decay of the N intermediate. By studying the effects of H/D exchange, evidence is found that the backbone structural changes involve transmembrane alpha-helices. It is proposed that these structural changes serve to modulate the local environment and protonation state of Asp96 during the photocycle and are also essential for formation of the proton conducting hydrogen bonded network which functions during Schiff base reprotonation.

Pseudomonas pseudomallei and melioidosis in China

Though melioidosis has been reported since 1912, it is still a new problem for most Chinese physicians and medical scientists. Because of the lack of understanding and clinical experiences in melioidosis, none had been reported until 1990 in the mainland of China. In view of China's open policy and health work the natural foci of Pseudomonas pseudomallei in South China, ie. Hainan, Guangdong and Guangxi Provinces, should be given sufficient concern. Efforts should be made in training physicians in the endemic areas to improve their knowledge about the disease and to avoid misdiagnosis.

Vibrational spectroscopy of bacteriorhodopsin mutants. Evidence that Thr-46 and Thr-89 form part of a transient network of hydrogen bonds

The role of Thr-46 and Thr-89 in the bacteriorhodopsin photocycle has been investigated by Fourier transform infrared difference spectroscopy and time-resolved visible absorption spectroscopy of site-directed mutants. Substitutions of Thr-46 and Thr-89 reveal alterations in the chromophore and protein structure during the photocycle, relative to wild-type bacteriorhodopsin. The mutants T89D and to a lesser extent T89A display red shifts in the visible lambda max of the light-adapted states compared with wild type. During the photocycle, T89A exhibits an increased decay rate of the K intermediate, while a K intermediate is not detected in the photocycle of T89D at room temperature. In the carboxyl stretch region of the Fourier transform infrared difference spectra of T89D, a new band appears as early as K formation which is attributed to the deprotonation of Asp-89. Along with this band, an intensity increase occurs in the band assigned to the protonation of Asp-212. In the mutant T46V, a perturbation in the environment of Asp-96 is detected in the L and M intermediates which corresponds to a drop in its pK alpha. These data indicate that Thr-89 is located close to the chromophore, exerts steric constraints on it during all-trans to 13-cis isomerization, and is likely to participate in a hydrogen-bonding network that extends to Asp-212. In addition, a transient interaction between Thr-46 and Asp-96 occurs early in the photocycle. In order to explain these results, a previously proposed model of proton transport is extended to include the existence of a transient network of hydrogen-bonded residues. This model can account for the protonation changes of key amino acid residues during the photocycle of bacteriorhodopsin.

Vibrational spectroscopy of bacteriorhodopsin mutants. Evidence that ASP-96 deprotonates during the M----N transition

The role of Asp-96 in the bacteriorhodopsin (bR) photocycle has been investigated by time-resolved and static low-temperature Fourier transform infrared difference spectroscopy. Bands in the time-resolved difference spectra of bR were assigned by obtaining analogous time-resolved spectra from the site-directed mutants Asp-96----Ala and Asp-96----Glu. As concluded previously (Braiman, M. S., Mogi, T., Marti, T., Stern, L. J., Khorana, H. G., and Rothschild, K. J. (1988) Biochemistry 27, 8516-8520) Asp-96 is predominantly in a protonated state in the M intermediate. Upon formation of the N intermediate, deprotonation of Asp-96 occurs. This is consistent with its postulated role as a key residue in the reprotonation pathway leading from the cytoplasm to the Schiff base. A broad band centered at 1400 cm-1, which increases in intensity upon N formation is assigned to the Asp-96 symmetric COO- vibration. The Asp-96----Ala mutation also causes a delay in the Asp-212 protonation which normally occurs during the L----M transition. It is concluded that Asp-96 donates a proton into the Schiff base reprotonation pathway during N formation and that it accepts a proton from the cytoplasm during the N----O or O----bR transition.

Vibrational spectroscopy of bacteriorhodopsin mutants. Evidence for the interaction of aspartic acid 212 with tyrosine 185 and possible role in the proton pump mechanism

The role of Asp-212 in the proton pumping mechanism of bacteriorhodopsin (bR) has been studied by a combination of site-directed mutagenesis and Fourier transform infrared difference spectroscopy. Difference spectra were recorded at low temperature for the bR----K and bR----M photoreactions of the mutants Asp-212----Glu, Asp-212----Asn, and Asp-212----Ala. Despite an increased proportion of the 13-cis form of bR (normally associated with dark adaptation), all of the mutants exhibited a light-adapted form containing as a principal component the normal all-trans retinal chromophore. The absence of a shift in the retinal C = C stretching frequency in these mutants indicates that Asp-212 is not a major determinant of the visible absorption wavelength maximum in light-adapted bR. It is unlikely that Asp-212 is the acceptor group for the Schiff base proton since both the Asp-212----Glu and Asp-212----Ala mutants formed an M intermediate. All of the Asp-212 mutants were missing a Fourier transform infrared difference band that had been assigned previously to protonation changes of Tyr-185. These results are discussed in terms of a model in which Tyr-185 and Asp-212 form a polarizable hydrogen bond and are positioned near the C13-Schiff base portion of the chromophore. These 2 residues may be involved in stabilizing the relative orientation of the F and G helices and isomerizing the retinal in a regioselective manner about the C13 = C14 double bond.

Ultraviolet-visible transient spectroscopy of bacteriorhodopsin mutants. Evidence for two forms of tyrosine-185----phenylalanine

The photocycle kinetics of the bacteriorhodopsin mutant Tyr-185----Phe has been investigated by UV-visible transient spectroscopy. Flash-induced spectral changes were measured from 100 ns to 500 ms using a gated optical multichannel analyzer on protein samples that were reconstituted in vesicles with Halobacterium halobium lipids. Tyr-185----Phe exhibits a pH-dependent absorbance spectrum reflecting contributions from two different species. At pH 6, the dominant photocycling species has a lambda max near 610 nm although the absorption maximum of light-adapted Tyr-185----Phe is at 581 nm. This red-shifted species does not form any M-like intermediate and undergoes a photocycle similar to that observed for deionized blue membrane. At pH 8, the dominant photoactive form exhibits a lambda max near 550 nm. This purple species, which is blue shifted 20 nm relative to wild-type bacteriorhodopsin, exhibits a photocycle similar to the wild type. However, M formation occurs in 8 microseconds, approximately three times faster than wild-type bacteriorhodopsin at pH 8. In addition, an unusually long lived intermediate absorbing at 610 nm is observed at high pH. In the UV region, a broad band near 300-310 nm is absent in the mutant relative to wild type, consistent with earlier measurements made at low temperature which suggest that Tyr-185 undergoes a change in protonation. Steady-state proton pumping action spectra indicate that the 550 nm species does transport protons but that the blue species is inactive. These results are discussed in terms of a model that hypothesizes that Tyr-185 is located close to the bacteriorhodopsin chromophore and stabilizes the interaction of helices F and G through formation of a polarizable bond with Asp-212.

Vibrational spectroscopy of bacteriorhodopsin mutants: evidence for the interaction of proline-186 with the retinylidene chromophore

Fourier-transform infrared difference spectroscopy has been used to study the role of the three membrane-embedded proline residues, Pro-50, Pro-91, and Pro-186, in the structure and function of bacteriorhodopsin. All three prolines were replaced by alanine and glycine; in addition, Pro-186 was changed to valine. Difference spectra were recorded for the bR----K and bR----M photoreactions of each of these mutants and compared to those of wild-type bacteriorhodopsin. Only substitutions of Pro-186 caused significant perturbations in the frequency of the C = C and C - C stretching modes of the retinylidene chromophore. In addition, these substitutions reduced bands in the amide I and II region associated with secondary structural changes and altered signals assigned to the adjacent Tyr-185. Pro-186----Val caused the largest alterations, producing a second species similar to bR548 and nearly blocking chromophore isomerization at 78 K but not at 250 K. These results are consistent with a model of the retinal binding site in which Pro-186 and Tyr-185 are located in direct proximity to the chromophore and may be involved in linking chromophore isomerization to protein structural changes. Evidence is also found that Pro-50 may be structurally active during the bR----K transition and that substitution of this residue by glycine preserves the normal protein structural changes during the photocycle.

Fourier transform infrared evidence for proline structural changes during the bacteriorhodopsin photocycle

Structural changes involving bacteriohodopsin proline residues have been investigated by Fourier transform infrared difference spectroscopy. Bacteriohodopsin (bR)-producing Halobacteria halobium were grown on a stringent medium containing either ring-perdeuterated proline or 15N-labeled proline. Comparison of the difference spectra obtained from the photoreactions of these labeled bR samples with those for unlabeled bR has led to the assignment of peaks due to proline vibrations. [proline-N15]bR exhibited a 15-cm-1 isotopic downshift of peaks in the 1420- to 1440-cm-1 region of the bR----K and bR----M difference spectra as well as a similar downshift of peaks found in the absolute absorption spectrum of bR. In contrast, [proline-D7]bR did not cause shifts in this region of the difference spectra. These results indicate that one or more prolines undergo a structural rearrangement during the bR photocycle involving the Xaa-Pro C--N peptide bond. This change may be directly coupled to the light-induced isomerization of the retinal chromophore from all-trans-retinal to 13-cis-retinal.