[Efficacy analysis of high-sensitivity troponin I concentration and its changes in the diagnosis of acute myocardial infarction]

Objective: To explore the feasibility and accuracy of 0-1 h high sensitivity cardiac troponin I (hs-cTnI) concentration and its changes in judging non-ST segment elevation myocardial infarction (NSTEMI), and to investigate the feasibility of a simplified process. Methods: Patients with acute chest pain and suspected NSTEMI who were admitted to the emergency department of Fuwai Hospital, the First Affiliated Hospital of Sun Yat-sen University and Nanjing First Hospital from January 2017 to September 2020 were selected. Hs-cTnI test was carried out for the selected patients at the time of visit (0 h) and 1 h after visit. According to the 0-1 h hs-cTnI diagnostic process and threshold standard recommended by European Society of Cardiology (ESC) guidelines in 2015, the laboratory adjudication was determined. Cardiologists who did not participate in the project design and did not know the results of hs-cTnI test performed the clinical judgment according to the routine diagnosis and treatment process of emergency department. Taking clinical judgment as the gold standard, the diagnostic efficacy of 0-1 h hs-cTnI concentration and its change recommended by the guidelines for judging NSTEMI in Chinese population was analyzed. The guide process was simplified. Under the condition of not considering the time of chest pain, the guideline threshold was used for test and judgement, and the diagnostic efficacy of the simplified process was evaluated. Results: A total of 1 534 patients were enrolled in the study, aged (62±12) years and 952 (62.1%) patients were male. Among them, 402 patients (26.2%) were clinically diagnosed as NSTEMI and 1 132 patients (73.8%) were diagnosed as non-NSTEMI. According to the diagnosis and determination process recommended by the guidelines, NSTEMI was excluded in 672 patients (42.8%), and 464 patients (30.2%) were diagnosed as NSTEMI. The consistency rate with clinical determination reached 92.4% (1 050/1 136), the sensitivity of excluding diagnosis was 99.5% (95%CI: 98.0%-99.9%), the negative predictive value was 99.7% (95%CI: 98.8%-99.9%), and the negative likelihood ratio was 0.008 (95%CI: 0.002-0.335). The diagnostic specificity was 92.6% (95%CI: 90.9%-94.0%), the positive predictive value was 81.9% (95%CI: 78.0%-85.2%), and the positive likelihood ratio was 12.739 (95%CI: 10.356-15.670). According to the simplified process, NSTEMI was excluded in 675 patients (44.0%), and 463 patients (30.2%) were diagnosed as NSTEMI. The consistency rate with clinical judgment was 92.4% (1 051/1 138), the sensitivity of exclusion diagnosis was 99.3% (95%CI: 97.6%-99.8%), the negative predictive value was 99.6% (95%CI: 98.6%-99.9%), and the negative likelihood ratio was 0.012 (95%CI: 0.004-0.389). The diagnostic specificity was 92.6% (95%CI: 90.9%-94.0%), the positive predictive value was 81.9% (95%CI: 78.0%-85.2%), and the positive likelihood ratio was 12.705 (95%CI: 10.328-15.630). There was no significant difference in diagnostic efficacy between the simplified process and the recommended process (all P>0.05). Conclusion: The diagnostic process for judging NSTEMI according to the 0-1 h hs-cTnI concentration and its change criteria recommended by the 2015 ESC guidelines is applicable in the Chinese population and remains highly accurate in judging NSTEMI without considering the duration of chest pain at the time of presentation.

[Clinical effects of free peroneal artery perforator flaps in repairing forefoot skin and soft tissue defect wounds assisted with three-dimensional computed tomography angiography]

Objective: To investigate the clinical effects of free peroneal artery perforator flaps in repairing forefoot skin and soft tissue defect wounds assisted with three-dimensional computed tomography angiography (3D-CTA). Methods: A retrospective observational study was conducted. From March 2017 to September 2019, 15 patients with skin and soft tissue defect wounds in the forefoot were treated in the Department of Burn and Plastic Surgery of Yidu Central Hospital of Weifang, including 12 males and 3 females, with age of 18-60 years. The wound area on admission was 3.0 cm×3.0 cm-9.0 cm×8.0 cm. The 3D-CTA examination before operation was performed to select the peroneal artery perforating vessels with appropriate length of vascular pedicle and good blood perfusion. According to the wound area and the perforating vessels of the peroneal artery located by 3D-CTA, the peroneal artery perforator flaps of 3.5 cm×3.5 cm-9.5 cm×8.5 cm carried with lateral sural cutaneous nerve was designed and cut, and the nerve was anastomosed with the nerve of the wound. The wound in the donor site of the flap was directly sutured or covered with medium-thickness skin graft from the thigh. The consistencies of type, diameter, and perforating position of perforating vessel of the peroneal artery detected by 3D-CTA before the operation with those of the actual measurement during operation were observed. The length of time for flap cutting and the survival of the flap after operation were recorded. During follow-up of 12 months after the operation, the patients were instructed to evaluate the foot function according to the Maryland foot function score standard, and the wound healing in the donor area and the occurrence of complications affecting the motor function of limb were observed. Data were statistically analyzed with paired sample t test. Results: The types of peroneal artery perforating vessels in patients measured during the operation were septocutaneous perforator of 12 cases, musculocutaneous perforator of 2 cases, and musculomuscular septal perforator of 1 case, which were consistent with those measured by preoperative 3D-CTA. The diameter of the peroneal artery perforating vessel measured by preoperative 3D-CTA was (1.38±0.17) mm, which was close to (1.40±0.19) mm measured during the operation (t=0.30, P>0.05). The horizontal distance from the starting point of the perforating vessel to the outer edge of the shank was (42±6) mm, and the vertical distance from the starting point of the perforating vessel to the level of the lateral ankle tip was (219±14) mm measured by preoperative 3D-CTA, which were respectively close to (43±6) and (221±15) mm of intraoperative measurement (with t values of 0.46 and 0.38, respectively, P>0.05). The length of time for cutting flap was (31±6) min. All flaps survived post operation without vascular crisis. During follow-up of 12 months after the operation, the foot function was evaluated as excellent in 11 cases, good in 3 cases, and fair in 1 case, the donor site wound healed well, the scar was not noticeable with no contracture, and the motor function of joints was not affected. Conclusions: Free peroneal artery perforator flap is one of the effective methods to reconstruct skin and soft tissue defect wounds in the forefoot, and the risk of surgery can be reduced when the anatomical location of the perforating vessels is confirmed by 3D-CTA.

[Analysis of risk factors for gestational diabetes mellitus in elderly multipara women in the next pregnancy]

Objective: To investigate the risk factors for gestational diabetes mellitus (GDM) in elderly multipara women in the next pregnancy. Methods: A total of 219 elderly multipara women with 2 consecutive delivery records in Tianjin Binhai New Area Tanggu Obstetrics and Gynecology Hospital from January 2018 to May 2019 were included. Among them, 141 had normal glucose tolerance (NGT) and 78 of them had GDM. The clinical data of the previous and current pregnancy were collected to analyze the risk factors of GDM in elderly multipara women. Results: The average ages of 219 elderly women in previous pregnancy and this pregnancy were (31.9±2.2) and (36.7±1.5) years old, and the prevalence of GDM was 35.62% (78 cases). Compared to NGT group, GDM patients had higher fasting blood glucose(previous (5.51±1.43) vs (4.63±0.62) mmol/L; current (5.26±0.63) vs (4.59±0.30) mmol/L, 1 h blood glucose(previous (11.74±2.36) vs (9.50±1.82) mmol/L; current (11.03±2.03) vs (9.51±1.14) mmol/L) in 75 g oral glucose tolerance test (OGTT) in both previous and current pregnancy. The rates of cesarean section, in both previous and current pregnancy were higher in GDM group (previous 34.6% vs 4.3%; current 52.6% vs 22.0%). Furthermore, prenatal weight and body mass index (BMI) of the previous pregnancy, pre-pregnancy weight and BMI, and prenatal BMI of this pregnancy were also higher in GDM group, and the differences were all statistically significant (all P<0.05). Logistic multivariate regression analysis indicated cesarean section history (OR=10.80, 95%CI: (4.09-28.54)), GDM history of previous pregnancy (OR=10.64, 95%CI: (4.02-28.20)), 75 g OGTT fasting blood glucose≥ 4.86 mmol/L (OR=2.70, 95%CI: (1.27-5.70)), 1 h blood glucose after glucose administration ≥ 8.45 mmol/L (OR=1.78, 95%CI: (1.37-2.31)) were risk factors for GDM in elderly multipara women of this pregnancy. Conclusion: The risk of GDM in elderly multipara women with a history of cesarean section and GDM increases significantly. Results of OGTT in previous pregnancy also has predictive value.

Progress on miRNA in giant panda (Ailuropoda melanoleuca)

MicroRNAs (miRNAs), a family of endogenous non-coding RNAs with a length of about 22 nucleotides, are widely found in eukaryotes. miRNAs can affect gene expression through specific bindings with mRNAs of target genes and participate in the regulation of a variety of biological processes. Giant panda is not only a unique rare animal in China, but also the focus of attention on wildlife preservation worldwide. In recent years, with the popularization of next-generation sequencing (NGS) technology, miRNAs in giant panda have been discovered and identified one after another. In this review, we focus on the research progress on miRNAs in giant panda, involved in immune response, mammary gland development, sperm freezing tolerance and other biological processes, and then discuss future research directions of miRNAs in giant panda, and thus providing the scientific references and new ideas for studying the regulatory mechanisms of miRNAs and promoting the breeding and protection of giant panda.

[Clinical effects of autologous platelet rich plasma gel combined with vacuum sealing drainage techno-logy in repairing refractory wounds]

Objective: To investigate the clinical effects of autologous platelet rich plasma (PRP) gel in combination with vacuum sealing drainage (VSD) technology in repairing refractory wounds. Methods: From March 2011 to January 2015, 44 patients with refractory wounds meeting the inclusion criteria were recruited into VSD alone group, who were admitted to the Department of Burns and Plastic Surgery of the Yidu Central Hospital of Weifang and received intermittent VSD treatment. From February 2015 to September 2019, 43 patients with refractory wounds meeting the inclusion criteria were recruited into PRP+ VSD group, who were admitted to the same unit as above-mentioned and received PRP combined with intermittent VSD treatment. The retrospective cohort study was conducted. There were 24 males and 20 females with age of (37.5±2.2) years in VSD alone group, and there were 25 males and 18 females with age of (37.0±2.5) years in PRP+ VSD group. The wound exudate of patients in the two groups before and 7 and 14 d after the first treatment were collected for bacterial culture, and the positive rate of bacterial culture was calculated. The wound healing of patients in the two groups was observed on 7, 14, and 21 d after the first treatment, and the wound healing rate was calculated. The complete wound healing time of patients in the two groups was recorded. The degree of wound pain of patients in the two groups was evaluated by the Visual Analog Scale (VAS) before and 14 d after the first treatment. The scar hyperplasia of patients in the two groups was evaluated by the Vancouver Scar Scale (VSS) in 1 and 2 months after the wound healed completely. The occurrence of adverse reactions of patients in the two groups during the whole period of treatment was observed and the incidence of adverse reactions was calculated. Data were statistically analyzed with analysis of variance for repeated measurement, chi-square test, paired t test, and Bonferroni correction. Results: The positive rates of bacterial culture in wound exudate of patients in PRP+ VSD on 7 and 14 d after the first treatment were 37.2% (16/43) and 11.6% (5/43), which were significantly lower than 56.8% (25/44) and 29.5% (13/44) in VSD alone group, χ(2)=4.212, 4.255, P<0.05. The wound healing rates of patients in PRP+ VSD group on 7 and 14, and 21 d after the first treatment were respectively (58±14)%, (70±13)%, (89±12)%, which were significantly higher than (41±11)%, (60±11)%, (74±12)% in VSD alone group, t=6.323, 3.820, 5.751, P<0.01. The complete wound healing time of patients in PRP+ VSD group was (30±6) d, which was significantly shorter than (61±8) d in VSD alone group, t=20.890, P<0.05. The VAS score of patients in PRP+ VSD group was significantly lower than that in VSD alone group on 14 d after the first treatment (t=13.904, P<0.01). The VSS score of patients in PRP+ VSD group was significantly lower than that in VSD alone group in 1 and 2 months after the wound healed completely (t=3.307, 3.637, P<0.01). The incidence of adverse reactions of patients in PRP+ VSD group during the whole period of treatment was 7.0% (3/43), which was significantly lower than 22.7% (10/44) in VSD alone group, χ(2)=4.245, P<0.05. Conclusions: Autologous PRP gel combined with VSD technology in repairing refractory wounds not only has good bacteriostatic effect, but also can increase wound healing rate, shorten wound healing time, alleviate wound pain, reduce scar hyperplasia, with less adverse reaction, which is worthy of promotion.

Total Synthesis of (±)-Clivonine via Diels-Alder Reactions of 3,5-Dibromo-2-pyrone

New synthetic routes to (±)-clivonine were devised starting with the Diels-Alder cycloadditions of 3,5-dibromo-2-pyrone with styrene pinacol boronate dienophiles. In the first-generation synthesis, the pivotal perhydroindoline system including the C5-hydroxyl group was constructed via a reaction sequence involving the Eschenmoser-Claisen rearrangement and regio/stereoselective epoxide opening reaction. In the second-generation synthesis, a radical-mediated cyclization approach was employed for the rapid assembly of the pyrrolidine ring. In this route, the C5-hydroxyl group provided by the dienophile in a stereochemically defined form was preserved throughout the synthesis.

[Effect of free medial plantar perforator flap in repairing deep burn wound on palm with the assistance of three dimensional computed tomography angiography]

Objective: To explore the effect of free medial plantar perforator flap in repairing deep burn wound on palm with assistance of three dimensional computed tomography angiography (CTA). Methods: From March 2015 to January 2018, 11 patients with deep burn wounds of palm were admitted to the Department of Burns and Plastic Surgery of Yidu Central Hospital of Weifang City, including 6 males and 5 females, aged 19-53 years. The wound area after debridement was 3.0 cm×2.5 cm-8.0 cm×6.0 cm. Before the operation, CTA of the foot was performed, and the three dimensional digital model was reconstructed by computer software to observe the initial position, course, and distribution of the arteries and veins in the donor site. The medial plantar perforator flap was designed according to the area and shape of the wound, with area of 3.5 cm×3.0 cm-8.5 cm×6.5 cm. After the wound was covered by the flap, the perforating branch of the medial plantar artery was anastomosed end to end with the carpal epithelial branch of the ulnar artery, the accompanying vein or the branch of the great saphenous vein was anastomosed end to end with the accompanying vein of the carpal epithelial branch of the ulnar artery, and the terminal branch of the saphenous nerve or the medial dorsal cutaneous nerve was anastomosed end to end with the superficial palmar branch of the ulnar nerve. The wound of donor site was covered with full-thickness skin graft from the outer thigh of the same side. The perforators of the medial plantar artery observed during the operation were compared with the reconstructed three dimensional CTA images. The survival of flap was observed, and the appearance and function of the flap were followed up and evaluated with trial standard for the evaluation of the functions of the upper limbs of the Hand Surgery Society of the Chinese Medical Association. Results: The initial position, course, and distribution of the perforator of the medial plantar artery during the operation were basically the same as those of the reconstructed three dimensional CTA images before the operation. All the flaps of patients survived after the operation. During the 6 months to 1 year follow-up, the appearance of flap was good, with no obvious swelling or pigmentation, but with good elasticity. The discrimination distance between the two points was 5.0-8.0 mm, and the flaps were evaluated as excellent in 4 cases, good in 6 cases, and fair in 1 case. Conclusions: The free medial plantar perforator flap is an ideal choice for repair of the deep burn wound on palm. Three dimensional CTA before the operation can detect condition of vascular variation, with high accuracy of vascular anastomosis during operation.

Transcriptome Sequencing Reveals the Differentially Expressed lncRNAs and mRNAs Involved in Cryoinjuries in Frozen-Thawed Giant Panda (Ailuropoda melanoleuca) Sperm

Sperm cryopreservation and artificial insemination are important methods for giant panda breeding and preservation of extant genetic diversity. Lower conception rates limit the use of artificial insemination with frozen-thawed giant panda sperm, due to the lack of understanding of the cryodamaging or cryoinjuring mechanisms in cryopreservation. Long non-coding RNAs (lncRNAs) are involved in regulating spermatogenesis. However, their roles during cryopreservation remain largely unexplored. Therefore, this study aimed to identify differentially expressed lncRNAs and mRNAs associated with cryodamage or freeze tolerance in frozen-thawed sperm through high throughput sequencing. A total of 61.05 Gb clean reads and 22,774 lncRNA transcripts were obtained. From the sequencing results, 1477 significantly up-regulated and 1,396 significantly down-regulated lncRNA transcripts from fresh and frozen-thawed sperm of giant panda were identified. GO and KEGG showed that the significantly dysregulated lncRNAs and mRNAs were mainly involved in regulating responses to cold stress and apoptosis, such as the integral component of membrane, calcium transport, and various signaling pathways including PI3K-Akt, p53 and cAMP. Our work is the first systematic profiling of lncRNA and mRNA in fresh and frozen-thawed giant panda sperm, and provides valuableinsights into the potential mechanism of cryodamage in sperm.

[Analysis of gene mutation and clinical characteristics in patients with idiopathic epilepsy]

Objective: To explore the association between gene mutations and clinical characteristics in Chinese patients with epilepsy. Methods: A total of twenty-three patients with idiopathic epilepsy admitted to the Xuanwu Hospital of Capital Medical University from January 2014 to July 2016 were included.The age at onset of epilepsy ranged from 8 months to 31 years.All patients were screened for mutations by next-generation of sequencing (NGS), using a targeted capture panel of epilepsy and related seizures to screen forgene causative for or related to epilepsy.Some mutations were verified for inheritance by Sanger sequencing of two generations in the family.The differences in clinical characteristics among different mutation carriers were compared. Results: A total of 38 mutations were identified in 23 patients.Most of the patients presented with tonic-clonic seizures, and most were not accompanied by mental retardation.Causative genes were dominated by those encoding ion channel, enzyme and proteins with special functions.Although mutation carriers for genes encoding ion channel proteins and those with special functions were not significantly different in age at onset, types of seizure, family history or complications(P>0.05), patients presenting with tonic-clonic seizures had higher frequency of mutations in genes encoding ion channel (15/15)than those encoding proteins with special function(16/20)(P=0.066). Conclusions: NGS is a useful technology in detecting mutations in patients with various types of epilepsy and aiding in etiological diagnosis of the disease.Tonic-clonic seizures may correlate with mutations in genes encoding ion channel.

Complete mitochondrial genome sequence of Jianmen-guan phasianus colchicus (Aves, Gallifoemes, phasianidae) and its phylogenetic analysis

Jianmen-guan phasianus colchicusare one of the most important and be cherished uncultivated animals, although, origins of the most J. phasianus colchicus remain unknown. Therefore, the complete mitochondrial genome of the J. phasianus colchicus (also named seven-colours J. phasianus colchicus, one of the oldest wild birds in China known for their preciousness) was obtained for the first time, the mitogenome is 166,786 bp in length, and it harbours 2rRNA genes, 13 protein-coding genes, 22tRNA genes, and a D-loop region. According to the phylogenetic tree, we can assume that Jianmen-guan and Xianju are within the same lineage, and J. phasianus colchicus is a different group with Red Jungle.

Relationship between drug resistance and the clustered, regularly interspaced, short, palindromic repeat-associated protein genes cas1 and cas2 in Shigella from giant panda dung

BACKGROUND

To detect drug resistance in Shigella obtained from the dung of the giant panda, explore the factors leading to drug resistance in Shigella, understand the characteristics of clustered, regularly interspaced, short, palindromic repeats (CRISPR), and assess the relationship between CRISPR and drug resistance.

METHODS

We collected fresh feces from 27 healthy giant pandas in the Giant Panda Conservation base (Wolong, China). We identified the strains of Shigella in the samples by using nucleotide sequence analysis. Further, the Kirby-Bauer paper method was used to determine drug sensitivity of the Shigella strains. CRISPR-associated protein genes cas1 and cas2 in Shigella were detected by polymerase chain reaction (PCR), and the PCR products were sequenced and compared.

RESULTS

We isolated and identified 17 strains of Shigella from 27 samples, including 14 strains of Shigella flexneri, 2 strains of Shigella sonnei, and 1 strain of Shigella dysenteriae. Further, drug resistance to cefazolin, imipenem, and amoxicillin-clavulanic acid was identified as a serious problem, as multidrug-resistant strains were detected. Further, cas1 and cas2 showed different degrees of point mutations.

CONCLUSION

The CRISPR system widely exists in Shigella and shares homology with that in Escherichia coli. The cas1 and cas 2 mutations contribute to the different levels of resistance. Point mutations at sites 3176455, 3176590, and 3176465 in cas1 (a); sites 3176989, 3176992, and 3176995 in cas1 (b); sites 3176156 and 3176236 in cas2 may affect the resistance of bacteria, cause emergence of multidrug resistance, and increase the types of drug resistance.

Analysis of the cytochrome c oxidase subunit II (COX2) gene in giant panda, Ailuropoda melanoleuca

The giant panda, Ailuropoda melanoleuca (Ursidae), has a unique bamboo-based diet; however, this low-energy intake has been sufficient to maintain the metabolic processes of this species since the fourth ice age. As mitochondria are the main sites for energy metabolism in animals, the protein-coding genes involved in mitochondrial respiratory chains, particularly cytochrome c oxidase subunit II (COX2), which is the rate-limiting enzyme in electron transfer, could play an important role in giant panda metabolism. Therefore, the present study aimed to isolate, sequence, and analyze the COX2 DNA from individuals kept at the Giant Panda Protection and Research Center, China, and compare these sequences with those of the other Ursidae family members. Multiple sequence alignment showed that the COX2 gene had three point mutations that defined three haplotypes, with 60% of the sequences corresponding to haplotype I. The neutrality tests revealed that the COX2 gene was conserved throughout evolution, and the maximum likelihood phylogenetic analysis, using homologous sequences from other Ursidae species, showed clustering of the COX2 sequences of giant pandas, suggesting that this gene evolved differently in them.

[Associations of sigmoid colon mucosal mast cells with bowel symptoms and psychological status in patients with irritable bowel syndrome with diarrhea]

OBJECTIVE

To investigate the bowel symptoms and psychological status of patients with irritable bowel syndrome (IBS) with diarrhea (IBS-D), and to verify whether sigmoid colon mucosal mast cells (MCs) and their activation have effect on the symptoms and psychological status of IBS-D patients.

METHODS

Patients meeting Rome Ⅲ diagnostic and subtyping criteria of IBS-D who visited the outpatient clinic of gastroenterology of Peking Union Medical College Hospital were consecutively enrolled between July 2009 and June 2012. IBS symptoms questionnaire was completed using face-to-face interview, and Hamilton Anxiety Scale (HAMA)/ Hamilton Depression Scale (HAMD) were administrated to evaluate psychological status, both by well-trained investigators. Mast cell tryptase monoclonal antibody was used for immunohistochemical staining to detect MCs and degranulated MCs in mucosal biopsy of sigmoid colon. MCs and degranulated MCs were blindly counted by a senior pathologist, and presented as number of cells in high power field (HPF) and percentage of activated MCs. Correlation analysis was performed using Spearman rank correlation analysis.

RESULTS

Ninety-seven patients with IBS-D were enrolled in this study, with mean age of (44±11) years. 70.10%(68 cases) of the IBS-D patients had comorbid anxiety and/or depression. The median total numbers of MCs, activated MCs, and percentage of activated MCs in sigmoid mucosa were 11.60 (7.09)/HPF, 2.00 (1.40) /HPF, and 17.50% (10.90%), respectively. Patients having abdominal pain/discomfort before bowel movement "every day with intermediate to high severity" had significantly larger numbers of total MCs in sigmoid colon compared with those with pain or discomfort "not every day and mild" [13.80(4.85)vs 7.60(5.90)/HPF, P=0.019]; the patient having "frequent" urge to have a bowel movement and mushy stools showed significantly higher percentage of activated MCs in sigmoid colon mucosa compared to those having the symptoms "some of the time" [18.75%(9.12%) vs 14.50%(13.14%), P=0.031; 21.33%(7.43%)vs 11.51%(10.65%)vs 18.42%(8.61%), P=0.030]. There was a positive correlation between the bowel movement during IBS-D onset and the percentage of activated MCs (r=0.221, P=0.030). There were no statistically significant differences in the total number of MCs and percentage of activated MCs between the patients with anxiety/depression and those without anxiety/depression (P=0.255, P=0.315). Scores of HAMA and HAMD were found not correlated with either total MCs number or percentage of activated MCs in sigmoid colon mucosa(all P>0.05).

CONCLUSIONS

The majority of IBS-D patients had comorbid anxiety and/or depression. The total number and activation status of MCs in sigmoid colon mucosa might be related with some intestinal symptoms in IBS-D patients. Psychological disorders might influence the pathogenesis and regression of IBS-D through brain-gut axis other than MCs in sigmoid colon mucosa.

The Surgical Management of H-Type Rectovestibular Fistula: A Novel Modification

Introduction H-type rectovestibular fistulas could be rare anorectal malformations or acquired diseases secondary to perianal infection. Various surgical procedures have been described in the literature, however the problem of recurrence still remains to be solved. We describe a novel modified surgical procedure and outcome in the management of these patients. Methods From 1999 to 2014, 14 patients who had an H-type rectovestibular fistula underwent the same surgical procedure performed by the same surgical team. Rectal-vestibular pull-through inside-out and endorectal mucosal advancement flap was used, including circumferential incision of the fistula from the opening on the rectal side, pulling the fistula inside-out, ligating the fistula, and mobilizing a rectal mucosal flap to cover the internal opening. Results All the patients have been followed-up for 12 months to 15 years with no recurrences and no incontinence. Conclusion Our surgical management is a simple, safe, and probable choice for the treatment of H-type rectovestibular fistula with favorable outcomes.

Molecular genetic analysis of heterosis in interspecific hybrids of Argopecten purpuratus x A. irradians irradians

Argopecten purpuratus and Argopecten irradians irradians hybridization was successfully performed and the hybrid offspring displayed apparent heterosis in growth traits. To better understand the genetic basis of heterosis, the genomic composition and genetic variation of the hybrids were analyzed with amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) markers. Seven of eight universal SSR primers displayed polymorphism in the hybrids and their parental groups, and hybrids inherited both parental geno-types at each locus. Using five primer combinations in AFLP analysis, 433 loci were amplified in the hybrids and their parental groups. The frequency of polymorphisms was 88.22%. F1 hybrids inherited 88.11 and 92.88% of AFLP bands from their parents. Some loci did not follow Mendelian Law, including 48 loci in parents that were lost, and 11 new loci that were amplified in the hybrids. The parameters of Nei's gene diversity, Shannon's Information index, genetic distance, and molecular variance between groups were calculated. The genetic differentiation between two hybrid groups (0.253) was smaller than that between hybrids and their parents (0.554 to 0.645), and was especially smaller than that between two parental groups (0.769). The high genetic similarity (0.9347) and low genetic differentiation (0.2531) between two hybrid groups suggests that these hybrid groups were genetically very close. Heterozygosities of hybrid groups were higher than those of parental groups, indicating that the hybrids had increased genetic diversity.

Study of the relationship between the expression of nerve growth factor and aneurysm formation and prognosis

We sought to investigate the effect of nerve growth factor (NGF) expression on the formation and prognosis of cerebral aneurysms. Forty-eight cases were selected following a diagnosis of cerebral aneurysm using computed tomography angiography and surgical confirmation. Thirty-four cases of healthy deaths were also chosen. The tissue was tested for NGF expression changes by reverse-transcription PCR, Western blot and histopathology, and NGF expression was compared between the cerebral aneurysm and healthy groups. The expression level of NGF in cerebral aneurysm tissue was significantly increased over that observed in control tissue. The abnormal expression of NGF is related to cerebral aneurysms. The elevated expression of NGF in cerebral aneurysms may be associated with a poor prognosis.

Relationship between abnormal NOS expression and the pathogenesis of cerebral aneurysm

We sought to investigate the relationship between abnormal expression of nitric oxide synthase (NOS) and pathogenesis of cerebral aneurysm. Brain tissues were collected from 36 patients with cerebral aneurysm confirmed by computer tomography with angiography or neurosurgical therapy. The control group consisted of 25 patients of similar age who had no vascular diseases, as confirmed by magnetic resonance imaging. Samples of cortical arterioles were collected. The structure of the aneurysms was detected by hematoxylin and eosin staining, and the expression of inducible NOS was detected by immunohistochemistry. NOS expression was significantly higher in the patient group than in the control group (patients: 30/36 strongly positive; control: 0/25 strongly positive; P < 0.05). In conclusion, the pathogenesis underlying cerebral aneurysm may be due to abnormal expression of NOS, degradation of the extracellular matrix, aggravation of a pro-inflammatory reaction, or a deficiency in arterial elasticity layer synthesis. These changes may result in a deficiency in vascular remodeling.

Estimation of the growth curve and heritability of the growth rate for giant panda (Ailuropoda melanoleuca) cubs

Giant panda cubs have a low survival rate during the newborn and early growth stages. However, the growth and developmental parameters of giant panda cubs during the early lactation stage (from birth to 6 months) are not well known. We examined the growth and development of giant panda cubs by the Chapman growth curve model and estimated the heritability of the maximum growth rate at the early lactation stage. We found that 83 giant panda cubs reached their maximum growth rate at approximately 75-120 days after birth. The body weight of cubs at 75 days was 4285.99 g. Furthermore, we estimated that the heritability of the maximum growth rate was moderate (h(2) = 0.38). Our study describes the growth and development of giant panda cubs at the early lactation stage and provides valuable growth benchmarks. We anticipate that our results will be a starting point for more detailed research on increasing the survival rate of giant panda cubs. Feeding programs for giant panda cubs need further improvement.

Aberrant promoter methylation of the CD4 gene in peripheral blood cells of mastitic dairy cows

Bovine mastitis is the most common and costly disease of dairy cattle. Cluster of differentiation 4 (CD4) is closely related to the immune response in mastitis. We quantified promoter CpG methylation levels of the CD4 gene in Chinese Holsteins with clinical mastitis (CM) and in healthy controls; these levels were quantitatively detected with bisulfite pyrosequencing assays and confirmed by cloning sequencing. We found that the bovine CD4 promoter had 16% more methyl groups in the cows with CM (75.0 ± 5.8%) compared to the controls (59.0 ± 8.5%). The decreased expression level of CD4 in CM cows may be downregulated by the increased DNA methylation levels in the CD4 promoter. Two-dimensional hierarchical clustering analyses showed large differences in promoter CD4 methylation between mastitic and healthy cows; the dendrogram clearly distinguished the cows with clinical mastitis from healthy controls based on methylation levels. The DNA methylation level of the CD4 gene was strongly influenced by mastitis status in all comparisons. We suggest that the DNA methylation level of the CD4 promoter can be used as a molecular marker for clinical mastitis in dairy cows.

A sensitive and specific PCR assay for the detection of Baylisascaris schroederi eggs in giant panda feces

Baylisascaris schroederi is one of the most common intestinal nematodes in giant pandas. It can cause severe baylisascariasis which is highly infectious in its natural hosts. A rapid and reliable diagnosis of parasite infections is crucial to protect giant pandas, as well as for environmental monitoring and disease surveillance. Here, we established a specific PCR assay for B. schroederi detection which was targeting a 331-bp long fragment of the mitochondrial cytochrome c oxidase subunit II (COII) gene. Fifty fresh fecal samples collected from captive giant pandas were tested by the established PCR assay and the traditional flotation technique. DNA extracted from a single B. schroederi egg could be successfully amplified, while no cross-reactivity was found with DNA from Ancylostoma caninum eggs. The detection rate of the PCR assay was 68%, which was higher than that of the traditional egg flotation (46%). Our findings demonstrated that the PCR assay is sensitive and specific for the detection and identification of B. schroederi eggs. Therefore, it could become a useful tool for the investigation of B. schroederi infections in giant pandas.

Construction and evaluation of high-quality n-ZnO nanorod/p-diamond heterojunctions

Vertically-aligned ZnO nanorods (NRs) arrays were synthesized by a low-temperature solution method on boron-doped diamond (BDD) films. The morphology, growth direction, and crystallinity of the ZnO NRs were studied by scanning electron microscopy, X-ray diffraction and cathodoluminescence. Electrical characterization of the ZnO NR/BBD heterostructures revealed characteristic p-n junction properties with an on/off ratio of about 50 at +/- 4 V and a small reverse leakage current approximately 1 microA. Moreover, the junctions showed an ideality factor around 1.0 at a low forward voltage from 0 to 0.3 V and about 2.1 for an increased voltage ranging from 1.2 to 3.0 V, being consistent with that of an ideal diode according to the Sah-Noyce-Shockley theory.

Facile and rapid synthesis of highly porous wirelike TiO2 as anodes for lithium-ion batteries

Highly porous wirelike TiO(2) nanostructures have been synthesized by a simple two-step process. The morphological and structural characterizations reveal that the TiO(2) wires typically have diameters from 0.4 to 2 μm, and lengths from 2 to 20 μm. The TiO(2) wires are highly porous and comprise of interconnected nanocrystals with diameters of 8 ± 2 nm resulting in a high specific surface area of 252 m(2) g(-1). The effects of experimental parameters on the structure and morphology of the porous wirelike TiO(2) have been investigated and the possible formation processes of these porous nanostructures are discussed. Galvanostatic charge/discharge tests indicate that the porous wirelike TiO(2) samples exhibit stable reversible lithium ion storage capacities of 167.1 ± 0.7, 152.1 ± 0.8, 139.7 ± 0.3, and 116.1 ± 1.1 mA h g(-1) at 0.5, 1, 2, and 5 C rates, respectively. Such improved performance could be ascribed to their unique porous and 1D nanostructures facilitating better electrolyte penetration, higher diffusion rate of electrons and lithium ion, and variation of accommodated volumes during the charge/discharge cycles.

Hypoglycemic effect and mechanism of a proteoglycan from ganoderma lucidum on streptozotocin-induced type 2 diabetic rats

BACKGROUND AND OBJECTIVES

Diabetes mellitus inducing a leading cause of morbidity are widespread in the entire globe. The present study was to investigate the antidiabetic potency and mechanism of a proteoglycan extract, named FYGL (Fudan-Yueyang-G. lucidum), from the fruiting bodies of Ganoderma Lucidum as published recently, using streptozotocin-induced type 2 diabetic mellitus (T2DM) rats.

MATERIAL AND METHODS

The T2DM model rats were treated with FYGL as well as metformin and rosiglitazone. The levels of plasma glucose and insulin were measured, and the expression and activity of the protein tyrosine phosphatase 1B (PTP1B) and the tyrosine phosphorylation level of the insulin receptor (IR) 3-subunit in the livers and skeletal muscles of the T2DM rats were analyzed by immunoprecipitation and Western blotting methods. In addition, the levels of free fatty acid and serum lipid profile were measured using commercial kits for those trailed rats.

RESULTS

The decrease in fasting plasma glucose and the increase in insulin concentration dose- and time-dependently in the T2DM rats treated by FYGL, comparable with that by the clinical drugs, metformin and rosiglitazone. The levels of the PTP1B expression and activity were decreased, and the tyrosine phosphorylation level of the IR 1-subunit was increased in the skeletal muscles of the T2DM rats. Furthermore, FYGL significantly decreased the levels of free fatty acid, triglyceride, total cholesterol and low density lipoprotein-cholesterol as well as increased the level of high density lipoprotein-cholesterol.

DISCUSSION

It is suggested that the hypoglycemic mechanisms of FYGL are caused by inhibition of the PTP1B expression and activity, consequently, regulation of the tyrosine phosphorylation level of the IR 13-subunit. As those results, FYGL also controlled the plasma biochemistry indexes relative to the type 2 diabetes-accompanied metabolic disorders. This is possibly the first report on the underlying mechanisms responsible for the antidiabetic effect of Ganoderma lucidum.

A Convenient and Efficient Synthesis of Naphthazarin

A convenient and efficient synthetic method of the important intermediate naphthazarin is presented starting from 1, 4, 5, 8-tetramethoxynaphthalene in an overall yield of 87%. Compared with the reported synthesis, this method has several advantages. Firstly, the reaction conditions are milder; secondly, the workup of each step is simpler and the yield is considerably higher; thirdly, all the reactions involved in the method are more suitable for large-scale preparations.

Down syndrome critical region protein 5 regulates membrane localization of Wnt receptors, Dishevelled stability and convergent extension in vertebrate embryos

The Glypican family of heparan sulfate proteoglycans regulates Wnt signaling and convergent extension (CE) in vertebrate embryos. They are predicted to be glycosylphosphatidylinositol (GPI)-tethered membrane-bound proteins, but there is no functional evidence of their regulation by the GPI synthesis complex. Down syndrome critical region protein 5 (Dscr5, also known as Pigp) is a component of the GPI-N-acetylglucosaminyltransferase (GPI-GnT) complex, and is associated with specific features of Down syndrome. Here we report that Dscr5 regulates CE movements through the non-canonical Wnt pathway. Both dscr5 overexpression and knockdown impaired convergence and extension movements. Dscr5 functionally interacted with Knypek/Glypican 4 and was required for its localization at the cell surface. Knockdown of dscr5 disrupted Knypek membrane localization and caused an enhanced Frizzled 7 receptor endocytosis in a Caveolin-dependent manner. Furthermore, dscr5 knockdown promoted specific Dishevelled degradation by the ubiquitin-proteosome pathway. These results reveal a functional link between Knypek/Glypican 4 and the GPI synthesis complex in the non-canonical Wnt pathway, and provide the new mechanistic insight that Dscr5 regulates CE in vertebrate embryos by anchoring different Wnt receptors at the cell surface and maintaining Dishevelled stability.

A functional composite cis-element for NF kappa b and RBJ kappa in the rat pregnancy-specific glycoprotein gene

The rat pregnancy-specific glycoprotein gene rnCGM3 is primarily expressed in the placenta. Previously, three DNase I footprinting sites (FPI, FPII, and FPIII) were identified in the rnCGM3 promoter region, a yeast one-hybrid screen was performed to identify the nuclear factors binding to the FPIII (5'-GCCTGGGAAAAAACTC-3') element, and RBPJ kappa, a downstream effector of the Notch signaling pathway, was identified as one of the FPIII-binding factors. In the present study, the NF kappa B member p65 was identified as another FPIII-binding factor. Electrophoretic mobility shift assays showed that NF kappa B members, including p50 and p65, bound to the FPIII site. The core binding sequence in the FPIII element for p50 and p65 is GGGAAA, which overlaps with that for RBPJ kappa. Competition exists between p50 and RBPJ kappa for binding to the FPIII element. Transient expression analyses revealed that p65 significantly stimulated the expression of a reporter gene directed by the NF kappa B core sequence in the FPIII element. However, RBPJ kappa could block this stimulation. These results suggest that the regulation of rnCGM3 expression involves both NF kappa B and RBPJ kappa, and they are mutually exclusive in the FPIII element.

5' Nuclease assays for the loci CCR5-+/Delta32, CCR2-V64I, and SDF1-G801A related to pathogenesis of AIDS

BACKGROUND

Variations within the human genome play important roles in human disease. To study variations related to susceptibility to AIDS, we have developed 5' nuclease assays that eliminate post-PCR molecular biology steps.

METHODS

TaqMan assays based on the 5' nuclease activity of Taq polymerase and fluorescent resonance energy transfer were developed to score alleles at the biallelic loci CCR5-+/Delta32, CCR2-V64I and SDF1-G801A. For each assay, 72 samples were analyzed. Data collection and analysis were performed on the Prism 7700 Sequence Detection System. For comparison with gel electrophoresis methods, each locus was also scored on a subset of 24 samples, using restriction enzymes or single-strand conformational polymorphism (SSCP).

RESULTS

Clear allelic discrimination was obtained on each of the 72 samples for all three TaqMan assays. The TaqMan scores for the subset of 24 samples were concordant with the restriction enzyme and SSCP scores.

CONCLUSIONS

Because of its simplicity, speed, and potential for automation and miniaturization, TaqMan is an excellent candidate for investigation of genetic variation in clinical, research, and forensic settings.

Creamatocrit and the nutrient composition of human milk

OBJECTIVE

We tested the hypothesis that creamatocrit, the length of the cream column separated from milk by centrifugation and expressed as a percentage of the length of the total milk column, is a useful measure of the lipid concentration and the energy content of human milk.

STUDY DESIGN

Milk samples from 17 mothers of preterm infants were analyzed prospectively, fresh as well as frozen and thawed, for creamatocrit measurement and nutrient composition.

RESULTS

Creamatocrit correlated strongly with lipid concentration and energy content of human milk, fresh or frozen and thawed. The energy content can be calculated from the regression equation: Energy (kcal/dl) = 5.99 x creamatocrit(%) + 32.5 for a fresh sample, and energy (kcal/dl) = 6.20 x creamatocrit(%) + 35.1 for a frozen sample.

CONCLUSION

Calculations of energy content from the creamatocrit measurement may be useful for an accurate assessment of energy intake in preterm infants fed human milk.

[Separation and identification of the llungianin A and B from the root of Pimpinella thellungiana Wolff]

Two compounds were isolated from the roots of Pimpinella thellungiana wolff. On the basis of spectral analysis (UV, IR, MS, 1HNMR, 1H-1H COSY, 13CNMR, 1H-13C COSY, DEPT), they were identified as 2-(1-ethoxy-2-hydroxy) propyl-4-methoxyphenol(I); 2-(1-ethoxy-2-hydroxy) propyl-4-methoxyphenyl-2-methyl-butyrate (II). They are new compounds named the llungianin A and B. Pharmacological tests showed that they have some hypotensive effects.

[A study on non-ulcer dyspepsia patients with electrogastrography and gastric emptying by using SPECT technique]

Non-ulcer dyspepsia (NUD) is very common in community population. However, its pathogenesis was controversial, particularly with respect to motility disorder. In this study electrogastrogram (EGG) and gastric emptying rate (GER) by using SPECT technique (test meal labelled with 99mTc-PHY and 113In-DTPA) were carried out in healthy subjects and 27 NUD patients. In EGG examination, the authors first proposed four parameters, i.e. peak time (PT), return time (RT), degeneration rate (DR) and arrhythemia rate (AR). Comparison of EGG between NUD patients and controls showed that AR, RT, DR in NUD patients were significantly higher or longer than these in the controls (P > 0.05). Solid phase GET in NUD patients were significantly delayed than that in the controls. No significant correlation was found between EGG and GET. A delay gastric emptying cannot be predicted with EGG examination only.

Identification of novel genes from stomach cancer cell lines by differential display

Gastric cancer is a leading cause of cancer death in many parts of the world. None of the tumor markers available to date provide for a reliable screening/diagnostic test. By using differential display technology on gastric cancer nonmetastatic (RF1) and metastatic (RF48) cell lines, we have isolated six novel cDNA clones. Five of them have not been previously identified. However, one of them appears to be the human homolog of the bovine oligomycin sensitivity conferral protein (oscp). Northern blot analysis showed that this clone is expressed at a much higher level in the metastatic (RF48) than the nonmetastatic (RF1) cancer cell line from the same patient. High level expression of the same gene is also observed in the breast cancer cell lines BT20 and T47D. The other five novel clones isolated showed either low or no expression in the RF1 and RF48 gastric cell lines, but variable levels of expression were detectable in breast cancers cell lines and normal tissues.

Intestinal lengthening experience in short-bowel swine

BACKGROUND

Traditional therapy for short-bowel syndrome is long-term, expensive and inconvenient; it is often associated with high morbidity and mortality. Thus, there has been increasing interest in the surgical management of this syndrome. Intestinal lengthening is attractive not only because of tapering of the dilated intestine, but also for preserving the intestine that is tapered. The purposes of this study were (a) to develop a reproducible surgical technique for intestinal lengthening and (b) to assess the response of the lengthened jejunum to a short-gut situation.

METHODS

Fourteen pigs weighing 13-20 kg were chosen for the study. The animals were divided into three groups: Group I: two pigs received a 20 cm jejunum lengthening only; Group II: six pigs received an 80% bowel resection only; Group III: six pigs received an 80% bowel resection, followed by a 20 cm loop lengthening in the residual jejunum four to seven weeks later. All were observed for a period from 4 to 28 weeks.

RESULTS

All lengthened loops, of either primary lengthening (Group I) or delayed lengthening (Group III) functioned well and showed no clinical leakage. Three pigs in Group II (bowel resection only) died of malnutrition at the 5th, 10th and 19th postoperative week, respectively. Only one pig in Group III died, 67 days after bowel lengthening, from intestinal obstruction. During sacrificing laparatomy, two pigs in Group III were found to have side to side enteroenteral fistulae between the lengthened loops. The lengthened bowel was found to be normal histologically.

CONCLUSIONS

These results proved that intestinal lengthening is technically feasible, and may be useful for patients suffering from surgical short-bowel syndrome and who have not been completely weaned off parenteral feeding.

[Effects of T4 monomer of Tripterygium wilfordii and artificial musk on experimental allergic neuritis]

Both T4 monomer of Tripterygium wilfordii and artificial musk had effects in regulating immune system and anti-inflammation. The effect of using artificial musk was the earlier the stronger. According to pharmacological features of the two drugs and pathogenesis of experimental allergic neuritis (EAN), 5 experimental groups were established, i.e., artificial musk prevented and treated groups, dexamethasone and T4 monomer treated groups, and control group.

RESULTS

T4 monomer could reduce the clinical score of model rabbits of EAN and significantly ameliorated inflammatory cell infiltration and demyelination. It was similar to dexamethasone. Although artificial musk had mild preventing and treating effects on the clinical and pathological changes of EAN, but was not statistically significant in comparing with control group. Our clinical or pathological data suggested that T4 monomer and dexamethasone were effective in the treatment of EAN, and that of artificial musk in preventing and treating EAN as indefinite.

Site-directed mutagenesis of the serotonin 5-hydroxytrypamine2 receptor: identification of amino acids necessary for ligand binding and receptor activation

Serotonin 5-hydroxytryptamine (5-HT)2 receptors are implicated in the etiology of mental disease and depression. Drugs that interact with the 5-HT2 receptor are used therapeutically to treat such illnesses, and their mechanisms of action are of great interest. In this study 5-HT2 receptor-ligand interactions were examined by site-directed mutagenesis in which three aspartic acid to asparagine mutants (Asn-120, Asn-155, and Asn-172) were created and expressed in NIH3T3 cells. The Asp-120 to asparagine mutant exhibited the same affinity for 125I-lysergic acid diethylamide (125I-LSD) as did the wild-type receptor and showed a decreased and GTP-insensitive binding affinity for the agonists 5-HT and (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-amino-propane (approximately 10-fold) and the antagonists ketanserin and mianserin (approximately 10-fold) but not spiperone. The mutation also abolished agonist-stimulated formation of [3H]polyphosphoinositides (PI). The Asn-155 mutant showed reduced binding affinity for 125I-LSD (Kd, 2.8 nM versus 0.6 nM for the wild-type receptor) and had reduced affinity for agonists (approximately 30-fold) and for antagonists (14-75-fold). However, the Asn-155 receptor retained GTP sensitivity and the ability to stimulate PI formation. The Asn-172 mutant retained the wild-type Kd value for 125I-LSD, exhibited only approximately 5-fold reduced affinity for 5-HT and (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane while retaining GTP-sensitive agonist binding showed no change in affinity for ketanserin, and had a small decrease in mianserin and spiperone binding (approximately 6-fold). The Asn-172 receptor also retained the ability to form PI. These results indicate that Asp-120 is necessary for allosteric activation of the guanine nucleotide-binding protein. Asp-155 is necessary for high affinity binding, probably by acting as a counterion for the amine group of the ligand. The different effects of the three mutations on ketanserin, mianserin, and spiperone binding affinity suggest that these antagonists may share overlapping but different binding domains. The information provided by this study may facilitate the design of therapeutic site-selective compound based on the structure of the 5-HT2 receptor.

The vibrational normal modes of beta-barrels in an IgG antibody molecule

Based on the quasi-continuity model, and using the method of group theory, we studied the normal vibrations of the VL- and the CHL-beta-barrels in an IgG molecule. We put emphasis on the Raman- and the infrared-active normal modes. The Raman modes we obtained include both the breathing motion mode (or the dominant low-frequency mode) which corresponds to the maximum peak in the Raman spectrum, and the normal modes that correspond to the lower peaks. Our calculated vibration frequencies are found to be in good agreement with the experimental results observed by Painter et al. (Biopolymers 20 (1981) 243). The method and work presented in this paper may improve Chou's quasi-continuity theory in calculating the vibrational modes of a beta-barrel protein.

Site-directed mutagenesis of the rat m1 muscarinic acetylcholine receptor. Role of conserved cysteines in receptor function

There are 9 cysteine residues in the rat m1 muscarinic acetylcholine receptor (mAChR) that are conserved among all five mammalian mAChR subtypes sequenced to date. To study the role of these cysteines in rat m1 mAChR function, site-directed mutagenesis was used to convert each Cys residue to Ser, and the mutant receptor genes were transfected into mAChR-deficient Chinese hamster ovary (CHO) cells. Substitution of Cys391 (extracellular loop III) or Cys421 and Cys435 (carboxyl terminus) produces receptors with wild type phenotype. Cells transfected with Ser98 or Ser178 (extracellular loops I and II, respectively) receptor genes display no carbachol-mediated hydrolysis of phosphoinositides (PI), and membranes prepared from these cells do not bind the muscarinic antagonist [3H] quinuclidinyl benzilate, even though the cells express transcripts of the m1 mAChR as determined by RNA hybridization analysis. Since biochemical evidence suggests that these cysteines form a disulfide bridge (Curtis, C. A. M., Wheatley, M., Bansal, S., Birdsall, N. J. M., Eveleigh, P., Pedder, E. K., Poyner, D., and Hulme, E. C. (1989) 264, 489-495), our findings imply that this disulfide linkage may be critical for formation of the ligand binding domain or for proper protein folding. The Ser394 mAChR (extracellular loop III) exhibits a 44% decrease in efficacy for carbachol-mediated stimulation of PI hydrolysis relative to the wild type receptor, but displays normal ligand binding affinities. The Ser407 m1 mAChR (transmembrane helix VII) displays a decreased efficacy for eliciting carbachol-mediated PI hydrolysis (39% that of CHO cells transfected with the wild type receptor) and a 4-fold shift to the right in the carbachol dose-response curve, which is consistent with the 4-fold decrease in carbachol affinity at the Ser407 m1 mAChR. In contrast, the Ser417 m1 mAChR (transmembrane helix VII) displays an increase in carbachol affinity and a shift to the left in the carbachol dose-response curve for PI hydrolysis. These findings suggest that cysteine residues in the seventh transmembrane helix of the m1 mAChR may influence agonist binding and the efficiency of receptor activation.

Site-directed mutagenesis of alpha 2A-adrenergic receptors: identification of amino acids involved in ligand binding and receptor activation by agonists

Molecular cloning of the alpha 2A-adrenergic receptor has shown that this receptor is a member of the gene superfamily of guanine nucleotide-binding protein (G protein)-coupled receptors. The alpha 2A-adrenergic receptor expressed in Chinese hamster ovary (CHO) cells attenuates and potentiates forskolin-stimulated cAMP production through independent signaling pathways. To examine the role of three conserved aspartic acid and two conserved serine residues in alpha 2A-adrenergic receptor function, we substituted asparagine for aspartic acid or alanine for serine and characterized the mutant receptors in stably transfected CHO cells. Asn113 mutant alpha 2-adrenergic receptors display no [3H] yohimbine specific binding, at concentrations up to 1000 nM. In transfected cells expressing the Asn113 mutant receptor, agonists, at concentrations up to 0.1 mM, produce small decreases (approximately 10% of wild-type values) in forskolin-stimulated cAMP and potentiate forskolin-stimulated cAMP concentrations in a dose-dependent manner, with EC50 values approximately 500-fold higher than those for the wild-type receptor. These findings suggest that Asp113 may be involved in high affinity binding of agonists and antagonists, as has been previously reported for beta 2-adrenergic and m1 muscarinic acetylcholine receptors. Asn79 mutant alpha 2-adrenergic receptors display high affinity agonist binding that is insensitive to guanine nucleotides, suggesting an altered receptor-G protein coupling. Furthermore, agonist binding to Asn79 mutant receptors elicits no change in forskolin-stimulated cAMP concentrations, similar to earlier findings that the corresponding residue in beta 2-adrenergic and muscarinic receptors is required for effector stimulation. Asp130 appears to influence receptor-G protein coupling. Mutation of this residue eliminates high affinity, guanine nucleotide-sensitive, agonist binding and produces a rightward shift in the dose-response curves for agonist-mediated inhibition of forskolin-stimulated cAMP production, compared with the wild-type receptor. Moreover, agonist potentiation of forskolin-stimulated cAMP levels is abolished if Asp130 is replaced by Asn, supporting the hypothesis that inhibition and potentiation of forskolin-stimulated cAMP production in CHO cells proceed through distinct signaling pathways. Characterization of Ala204 mutant alpha 2A-adrenergic receptors suggests a possible role for Ser204 in hydrogen bond interactions with the para-hydroxyl group of the phenyl ring of the catecholamines, as has been previously described for the corresponding serine in beta 2-adrenergic receptors.(ABSTRACT TRUNCATED AT 400 WORDS)

Site-directed mutagenesis of m1 muscarinic acetylcholine receptors: conserved aspartic acids play important roles in receptor function

Muscarinic acetylcholine receptors contain a region encompassing the second and third transmembrane domains that is rich in conserved aspartic acid residues. To investigate the role of four conserved aspartic acids at positions 71, 99, 105, and 122 in muscarinic receptor function, point mutations in the rat m1 muscarinic receptor gene were made that converted each Asp to Asn, and wild type or mutant genes were stably expressed in Chinese hamster ovary cells that normally lack muscarinic receptors. Substitution of Asp71 or Asp122 with Asn produced mutant receptors that displayed high affinity for carbachol but decreased efficacy and potency, respectively, in agonist-induced activation of phosphoinositide hydrolysis, suggesting that these residues may mediate receptor-GTP binding protein interactions. Substitution of Asp99 or Asp105 with Asn produced marked decreases in ligand binding affinities and/or covalent incorporation of [3H] propylbenzilylcholine mustard, suggesting that these residues may be involved in receptor-ligand interactions.

Site-directed mutagenesis of human beta-adrenergic receptors: substitution of aspartic acid-130 by asparagine produces a receptor with high-affinity agonist binding that is uncoupled from adenylate cyclase

By using oligonucleotide-directed mutagenesis, we have produced a point mutation (guanine to adenine) at nucleotide 388 of the gene for human beta-adrenergic receptor (beta AR) that results in a substitution of asparagine for the highly conserved aspartic acid at position 130 in the putative third transmembrane domain of the human beta AR ([Asn130]beta AR). We have examined the functional significance of this mutation in B-82 cells continuously expressing the mutant [Asn130]beta AR. The mutant [Asn130]beta AR displayed normal antagonist binding but unusually high-affinity agonist binding (5- to 10-fold higher than wild-type beta AR), consistent with a single class of high-affinity binding sites. The mutant beta AR displayed guanine nucleotide-sensitive changes in agonist affinity (3- to 5-fold shift) implying an interaction between the beta AR and the stimulatory guanine nucleotide-binding regulatory protein; however, the ability of guanine nucleotides to alter agonist affinity was attenuated. Addition of saturating concentrations of isoproterenol to cell cultures expressing mutant [Asn130]-beta ARs had no effect on intracellular levels of cAMP, indicating that the mutant beta AR is unable to affect stimulation of adenylate cyclase. These results indicate that substitution of the aspartic acid with asparagine at residue 130 of the human beta AR dissociates the well-characterized guanine nucleotide effects on agonist affinity from those on activation of the stimulatory guanine nucleotide-binding regulatory protein and adenylate cyclase and suggests the existence of two distinct counterions for the amine portion of catecholamines that are associated with high- and low-affinity agonist binding states of beta AR.

Site-directed mutagenesis and continuous expression of human beta-adrenergic receptors. Identification of a conserved aspartate residue involved in agonist binding and receptor activation

Using a new expression vector that allows stable and steroid inducible expression of the human beta 2-adrenergic receptor in mouse L cells, we have examined the functional significance of the highly conserved aspartate residue in the putative second transmembrane region of the receptor. Substitution of aspartate 79 with asparagine produced a mutant receptor that displays the expected affinity and stereoselectivity for antagonists but a 40-, 140-, and 240-fold reduction in its affinity for isoproterenol, epinephrine, and norepinephrine, respectively. This receptor mutant does not display guanine nucleotide-sensitive high affinity binding of agonists. Addition of saturating concentrations of isoproterenol to cell cultures expressing the mutant receptor produces a slight, albeit significant, increase in intracellular levels of cyclic AMP as compared to cells expressing wild type receptor. These observations demonstrate that substitution of aspartate with asparagine at residue 79 in the human beta-adrenergic receptor differentially affects the binding of catecholamines and produces a functional uncoupling of receptors and stimulatory guanine nucleotide regulatory proteins (Gs). These data are consistent with a role for aspartate 79 as a counterion to the amine in catecholamines and in agonist-induced activation of the beta-adrenergic receptor associated with high affinity ligand binding, Gs coupling, and adenylate cyclase stimulation.