GGA1 acts as a spatial switch altering amyloid precursor protein trafficking and processing

The beta-amyloid (Abeta) precursor protein (APP) is cleaved sequentially by beta-site of APP-cleaving enzyme (BACE) and gamma-secretase to release the Abeta peptides that accumulate in plaques in Alzheimer's disease (AD). GGA1, a member of the Golgi-localized gamma-ear-containing ARF-binding (GGA) protein family, interacts with BACE and influences its subcellular distribution. We now report that overexpression of GGA1 in cells increased the APP C-terminal fragment resulting from beta-cleavage but surprisingly reduced Abeta. GGA1 confined APP to the Golgi, in which fluorescence resonance energy transfer analyses suggest that the proteins come into close proximity. GGA1 blunted only APP but not notch intracellular domain release. These results suggest that GGA1 prevented APP beta-cleavage products from becoming substrates for gamma-secretase. Direct binding of GGA1 to BACE was not required for these effects, but the integrity of the GAT (GGA1 and TOM) domain of GGA1 was. GGA1 may act as a specific spatial switch influencing APP trafficking and processing, so that APP-GGA1 interactions may have pathophysiological relevance in AD.     

Tyrosine phosphatase-like protein (IA-2) and glutamic acid decarboxylase (GAD65) autoantibodies: a study of Chinese patients with diabetes mellitus

Type 1 diabetes in most Asian populations may not have a salient autoimmune basis when assessed with single determinations of the major markers, islet cell antibodies (ICAs) and glutamic acid decarboxylase antibodies (GAD65ab). With the inclusion of antibodies to tyrosine phosphatase-like protein IA-2 (IA-2ab) as an additional major marker, we re-examined autoimmune diabetes in a group of Chinese patients. We studied 272 subjects at various stages of disease with blood samples procured for biochemical analysis. ICAs were measured by immunofluorescence, GAD65ab and IA-2ab by radioimmunoassay. Sixty-seven patients fulfilled clinical diagnosis of type 1 diabetes and the remaining 205 patients were type 2. Prevalence of single autoantibody type in recent-onset type 1 diabetes ( < 1 year duration; n = 47) showed 10.6% with ICAs, 44.7% GAD65ab and 36.2% IA-2ab. GAD65ab account for more than two-thirds of the markers found in type 1 diabetes. Combined analysis further showed that 51.1% had at least one antibody type, 31.9% with two or more antibodies and 8.5% with all three antibodies. Islet autoimmunity presence in childhood-onset type 1 diabetes improved with the addition of IA-2ab, though less impact was seen in the adult-onset. Similarly, combined analysis for type 2 patients with recent diabetes showed a modest increase to 13% with islet autoimmunity compared to 8% when assessed by GAD65ab alone. Combining IA-2ab and GAD65ab assays results detected slightly more immune-mediated diabetes, compared to using a single GAD65ab determination. Non-autoimmune causes need to be considered in the pathogenesis of type 1 diabetes in Chinese, particularly in adults.     

大鼠胸腺降黑素受体的鉴定及生物学特性

应用放射配体结合法证实大鼠胸腺内存在降黑素特异结合部位，该结合位点可以满足特异结合部位的基本条件：１．低结合容量；２．高亲和力；３．可饱和性；４．可逆性；５．对降黑素高度特异性。此外，该特异结合位点具昼夜节律；亚细胞分布的研究表明以细胞核含量最高，线粒体次之，并具有年龄依赖性降低，以出生时最高。     

Conservative management of early endometrial adenocarcinoma with repeat curettage and hormone therapy under assistance of hysteroscopy and laparoscopy

We report a rare case of early-stage endometrial adenocarcinoma in a 22 year old nullipara with polycystic ovaries undergoing conservative treatment. Pretreatment evaluation including tumour grade, depth of myometrial invasion, tumour size, hormone receptor status and flow cytometric analysis indicated a favourable prognosis. The patient underwent repeat endometrial curettage and a 6 month period of therapy with megestrol acetate and tamoxifen. A combination contraceptive pill was then prescribed to ensure withdrawal of the menstrual cycle thereafter. Now, 1 year after the last curettage, there is no evidence of disease. During the treatment period, hysteroscopy allowed for a more precise approach in panoramically examining the tumour nest in the endometrial cavity, and the subsequent endometrial response to hormone therapy. Laparoscopy using bulldog clamps applied to the isthmic portion of the Fallopian tubes prevented i.p. spread of endometrial tissue from retrograde regurgitation during hysteroscopy. Laparoscopic ovarian electrocautery resulted in the reduction of abnormal hypervascularization on the surface of polycystic ovaries postoperatively but caused a peri-ovarian adhesion complication. It is interesting that this case posed a unique opportunity to demonstrate the tumour regression under the assistance of laparoscopy and hysteroscopy.      

Contribution of magnetic resonance microscopy in the 12-week neurotoxicity evaluation of carbonyl sulfide in Fischer 344 rats

In this carbonyl sulfide (COS) study, magnetic resonance microscopy (MRM) and detailed light microscopic evaluation effectively functioned in parallel to assure that the distribution and degree of pathology in the brain was accurately represented. MRM is a powerful imaging modality that allows for excellent identification of neuroanatomical structures coupled with the ability to acquire 200 or more cross-sectional images of the brain, and the ability to display them in multiple planes. F344 rats were exposed to 200-600 ppm COS for up to 12 weeks. Prior to MRM, rats were anesthetized and cardiac perfused with McDowell Trump's fixative containing a gadolinium MR contrast medium. Fixed specimens were scanned at the Duke Center for In Vivo Microscopy on a 9.4 Tesla magnetic resonance system adapted explicitly for microscopic imaging. An advantage of MRM in this study was the ability to identify lesions in rats that appeared clinically normal prior to sacrifice and the opportunity to identify lesions in areas of the brain which would not be included in conventional studies. Other advantages include the ability to examine the brain in multiple planes (transverse, dorsal, sagittal) and obtain and save the MRM images in a digital format that allows for postexperimental data processing and manipulation. MRM images were correlated with neuroanatomical and neuropathological findings. All suspected MRM images were compared to corresponding H&E slides. An important aspect of this study was that MRM was critical in defining our strategy for sectioning the brain, and for designing mechanistic studies (cytochrome oxidase evaluations) and functional assessments (electrophysiology studies) on specifically targeted anatomical sites following COS exposure.     

Evaluation of the proficiency of trained non-laboratory health staffs and laboratory technicians using a rapid and simple HIV antibody test

In Cambodia, nearly half of pregnant women attend antenatal care (ANC), which is an entry point of services for prevention of mother-to-child transmission of HIV (PMTCT). However, most of ANC services are provided in health centres or fields, where laboratory services by technicians are not available. In this study, those voluntary confidential counselling and testing (VCCT) counsellors involved in PMTCT were trained by experienced laboratory technicians in our centre on HIV testing using Determine (Abbot Laboratories) HIV1/2 test kits through a half-day training course, which consisted of use of a pipette, how to process whole blood samples, and how to read test result. The trained counsellors were midwives working for ANC and delivery ward in our centre without any experience on laboratory works. The objective of this study was to assess the feasibility of the training by evaluating the proficiency of the trained non-laboratory staffs. The trained counsellors withdrew blood sample after pre-test counselling following ANC, and performed the rapid test. Laboratory technicians routinely did the same test and returned reports of the test results to counsellors. Reports by the counsellors and the laboratory technicians were compared, and discordant reports in two groups were re-tested with the same rapid test kit using the same blood sample. Cause of discordance was detected in discussion with both groups. Of 563 blood samples tested by six trained VCCT counsellors and three laboratory technicians, 11 samples (2.0%) were reported positive in each group, however four discordant reports (0.7%) between the groups were observed, in which two positive reports and two negative reports by the counsellors were negative and positive by the laboratory technicians, respectively. Further investigation confirmed that all the reports by the counsellors were correct, and that human error in writing reports in the laboratory was a cause of these discordant reports. These findings lead us the conclusion that the half-day training using the rapid and simple test was feasible for non-laboratory staffs to attain enough proficiency to implement VCCT services for PMTCT in resource-limited settings, and that human error was more likely to occur in laboratory before giving reports to counsellors.     

Engineered NS1 for Sensitive,Specific Zika Virus Diagnosis from Patient Serology

Dengue virus (DENV) and Zika virus (ZIKV) belong to the Flaviviridae family of viruses spread by Aedes aegypti mosquitoes in tropical and subtropical areas. Accurate diagnostic tests to differentiate the 2 infections are necessary for patient management and disease control. Using characterized ZIKV and DENV patient plasma in a blind manner, we validated an ELISA and a rapid immunochromatographic test for ZIKV detection. We engineered the ZIKV nonstructural protein 1 (NS1) for sensitive serologic detection with low cross reactivity against dengue and developed monoclonal antibodies specific for the ZIKV NS1 antigen. As expected, the serologic assays performed better with convalescent than acute plasma samples; the sensitivity ranged from 71% to 88%, depending on the performance of individual tests (IgM/IgG/NS1). Although serologic tests were generally less sensitive with acute samples, our ZIKV NS1 antibodies were able to complement the serologic tests to achieve greater sensitivity for detecting early infections.     

Toxic Clostridioides (formerly Clostridium) difficile colitis: No longer a diarrhea associated infection

BackgroundClostridioides difficile infection (CDI) is traditionally taught to be an antibiotic associated diarrheal infection. This diagnosis is based on the presence of clinical symptoms (usually defined as more than 3 watery, loose or unformed stool within 24 h) coupled with a diagnostic test. There is now a new presentation of CDI, including progression to toxic megacolon, in patients without diarrhea.MethodsWe report a case series of 9 surgical patients from a single institution who developed CDI without preceding diarrhea.ResultAll 9 patients had CDI with positive laboratory testing for C. difficile toxin. They, however, presented with a lack of or minimal bowel movements. Six patients had rapid development of abdominal distention, 1 patient had a single episode of watery stool in 3 days, while the other 2 patients presented with constipation. Seven patients received stool softeners, suppositories and/or enemas for presumed constipation. Four patients had a mild course of infection and were successfully treated medically. The other 5 patients developed toxic megacolon, and eventually required total abdominal colectomy. Out of the 5 patients that required total colectomy, 2 expired.ConclusionCDI must be suspected in patients who rapidly develop abdominal distention, vague abdominal complaints or change in bowel function even in the absence of diarrhea, especially if coupled with multi-system organ failure.     

Comparative pharmacokinetics and tissue distribution of the d-enantiomers of para-substituted methylphenidate analogs.

A comparative study of the plasma pharmacokinetics and tissue distribution of the d-threo enantiomers of methylphenidate (MPH), para-bromomethylphenidate (p-Br MPH), and para-methoxymethylphenidate (p-OCH3 MPH) was conducted in rats after i.p. administration of a 37 micromol/kg dose. The plasma kinetic data was fit to a two-compartment model with absorption and lag time as well as evaluated by noncompartmental methods. All three compounds attained maximal concentration within 10 min of injection. Calculated mean residence time and elimination half-life values for d-p-Br MPH were significantly longer than those for d-MPH and d-p-OCH3 MPH, and clearance of the bromo derivative was substantially lower than the latter two compounds. Tissue distribution studies of the three d-threo enantiomers revealed that para-substitution of d-MPH had a profound effect on the distribution pattern of these drugs. The highest concentration of drug was found in the kidney and lung for d-MPH, lung and liver for d-p-Br MPH, and lung and brain for d-p-OCH3 MPH. The bromo derivative was found in the highest concentration in the central nervous system at 30, 120, and 180 min whereas levels of d-MPH were twice as high as d-p-OCH3 MPH at 30 min but slightly lower than the latter at 120 min. Related studies on the lipophilicity, plasma protein binding, and resistance to plasma degradation of these compounds were also conducted. The combined data from these experiments along with the pharmacokinetics and central nervous system distribution of these drugs provide explanations for discrepancies between the in vivo and in vitro activity of these compounds described in previous work.