The cell-polarity protein Par6 links Par3 and atypical protein kinase C to Cdc42

PAR (partitioning-defective) proteins, which were first identified in the nematode Caenorhabditis elegans, are essential for asymmetric cell division and polarized growth, whereas Cdc42 mediates establishment of cell polarity. Here we describe an unexpected link between these two systems. We have identified a family of mammalian Par6 proteins that are similar to the C. elegans PDZ-domain protein PAR-6. Par6 forms a complex with Cdc42-GTP, with a human homologue of the multi-PDZ protein PAR-3 and with the regulatory domains of atypical protein kinase C (PKC) proteins. This assembly is implicated in the formation of normal tight junctions at epithelial cell-cell contacts. Thus, Par6 is a key adaptor that links Cdc42 and atypical PKCs to Par3.

Imaging of the elastic properties of tissue--a review

Recently, a number of methods have been developed that make it possible to image the elastic properties of soft tissues. Because certain types of tissues such as malignant lesions, for example, have elastic properties that are markedly different from surrounding tissues, elasticity imaging could provide a significant adjunct to current diagnostic ultrasonic methods. Further, elasticity imaging techniques could be used to augment the study of tissues that change their elastic properties, such as skeletal and cardiac muscle. In this paper, we survey some of the previous work done in the related field of biomechanics, and we review measurement techniques from the 1950s to the 1980s. Different approaches to elastic imaging and signal processing are then discussed and a lexicography for elastic imaging is introduced. It is hoped that this nomenclature will provide a meaningful categorization of various approaches and will make evident the inherent parameters displayed and conditions applied in deriving the resulting images. Key assumptions and signal processing approaches are also reviewed. Finally, directions for future work are suggested.

Increased expression of programmed cell death protein 1 on NK cells inhibits NK-cell-mediated anti-tumor function and indicates poor prognosis in digestive cancers

Abnormal expression of activating/inhibitory receptors leads to natural killer (NK) cells dysfunction in tumor. Here we show that programmed cell death protein 1 (PD-1), a well-known immune checkpoint of T cells, is highly expressed on peripheral and tumor-infiltrating NK cells from patients with digestive cancers including esophageal, liver, colorectal, gastric and biliary cancer. The increased PD-1 expression on NK cells indicates poorer survival in esophageal and liver cancers. Blocking PD-1/PD-L1 signaling markedly enhances cytokines production and degranulation and suppresses apoptosis of NK cells in vitro. PD-1/PD-L1 exerts inhibitory effect through repressing the activation of PI3K/AKT signaling in NK cells. More importantly, a PD-1 blocking antibody was found to significantly suppress the growth of xenografts in nude mice, and this inhibition of tumor growth was completely abrogated by NK depletion. These findings strongly suggested that PD-1 is an inhibitory regulator of NK cells in digestive cancers. PD-1 blockade might be an efficient strategy in NK cell-based tumor immunotherapy.

The SCID-hu mouse as a model for HIV-1 infection

During normal fetal ontogeny, one of the first organs to harbour CD4-positive cells is the thymus. This organ could therefore be one of the earliest targets infected by human immunodeficiency virus type 1 (HIV-1) in utero. HIV-1-infected cells and pathological abnormalities of the thymus have been seen in HIV-1-infected adults and children, and in some fetuses aborted from infected women. Studies of HIV-1 pathogenesis have been hampered by lack of a suitable animal model system. Here we use the SCID-hu mouse as a model to investigate the effect of virus infection on human tissue. The mouse is homozygous for the severe combined immunodeficiency (SCID) defect. The model is constructed by implanting human fetal liver and thymus under the mouse kidney capsule. A conjoint human organ develops, which allows normal maturation of human thymocytes. After direct inoculation of HIV-1 into these implants, we observed severe depletion of human CD4-bearing cells within a few weeks of infection. This correlated with increasing virus load in the implants. Thus the SCID-hu mouse may be a useful in vivo system for the study of HIV-1-induced pathology.

Longitudinal study of earthquake-related PTSD in a randomly selected community sample in north China

OBJECTIVE

This study longitudinally described rates of posttraumatic stress disorder (PTSD) in two groups with different levels of severity of exposure to an earthquake in North China. The effects of diagnostic criteria on the frequency of detected PTSD were also examined.

METHOD

Subjects were randomly sampled in two villages at different distances from the earthquake epicenter. A total of 181 and 157 subjects were assessed at 3 months and 9 months after the earthquake, respectively, for PTSD by using both DSM-IV and DSM-III-R criteria. The brief version of the World Health Organization Quality of Life Assessment and three subscales of the SCL-90-R were also administered at both assessment points.

RESULTS

The village with a higher level of initial exposure to the earthquake and a higher level of postearthquake support had a lower frequency of PTSD than the village with a lower level of initial exposure and less postearthquake support. The rate of onset of DSM-IV PTSD within 9 months for the two villages was 19.8% and 30.3%, respectively. In both villages, the rate of onset of earthquake-related PTSD within 9 months was 24.2% by using DSM-IV criteria and 41.4% by using DSM-III-R criteria. The introduction in DSM-IV of a criterion requiring clinically significant distress or impairment in functioning for a diagnosis of PTSD was a major contributor to the lower rate of DSM-IV PTSD.

CONCLUSIONS

PTSD may be as prevalent and persistent in disaster victims in China as in those elsewhere. Prompt and effective postdisaster intervention could mitigate the impact of initial exposure and reduce the probability of PTSD occurrence. Caution should be used in comparing rates of postdisaster PTSD identified by using different diagnostic criteria.

Recombinant interleukin-2 directly augments the cytotoxicity of human monocytes

Interleukin-2 (IL-2), originally described as a growth factor required for sustained proliferation of T cells in vitro is a glycoprotein hormone of known structure which appears to be important for the generation of immune responses in vivo. As well as T lymphocytes, B lymphocytes and large granular lymphocytes with natural killer activity (NK cells) can also respond to IL-2. The action of IL-2 seemed to be limited specifically to lymphocytes, however, and the term 'T-lymphocytotrophic hormone' was used. Here we provide evidence that human monocytes display a substantially increased cytotoxic activity as a direct and rapid response to human recombinant IL-2 but not to human recombinant glycosylated interferon-gamma (IFN-gamma) or lipopolysaccharide. Our results reveal a previously unknown function of IL-2 and suggest its possible involvement in monocyte-T cell interactions.

Final follow-up of the Multicentre Aneurysm Screening Study (MASS) randomized trial of abdominal aortic aneurysm screening

BACKGROUND

The long-term effects of abdominal aortic aneurysm (AAA) screening were investigated in extended follow-up from the UK Multicentre Aneurysm Screening Study (MASS) randomized trial.

METHODS

A population-based sample of men aged 65-74 years were randomized individually to invitation to ultrasound screening (invited group) or to a control group not offered screening. Patients with an AAA (3·0 cm or larger) detected at screening underwent surveillance and were offered surgery after predefined criteria had been met. Cause-specific mortality data were analysed using Cox regression.

RESULTS

Some 67 770 men were enrolled in the study. Over 13 years, there were 224 AAA-related deaths in the invited group and 381 in the control group, a 42 (95 per cent confidence interval 31 to 51) per cent reduction. There was no evidence of effect on other causes of death, but there was an overall reduction in all-cause mortality of 3 (1 to 5) per cent. The degree of benefit seen in earlier years of follow-up was slightly diminished by the occurrence of AAA ruptures in those with an aorta originally screened normal. About half of these ruptures had a baseline aortic diameter in the range 2·5-2·9 cm. It was estimated that 216 men need to be invited to screening to save one death over the next 13 years.

CONCLUSION

Screening resulted in a reduction in all-cause mortality, and the benefit in AAA-related mortality continued to accumulate throughout follow-up.

REGISTRATION NUMBER

ISRCTN37381646 (http://www.controlled-trials.com).

Hepatitis C virus RNA polymerase and NS5A complex with a SNARE-like protein

Hepatitis C virus (HCV) NS5A is a phosphoprotein that possesses a cryptic trans-activation activity. To investigate its potential role in viral replication, we searched for the cellular proteins interacting with NS5A protein by yeast two-hybrid screening of a human hepatocyte cDNA library. We identified a newly discovered soluble N-ethylmaleimide-sensitive factor attachment protein receptor-like protein termed human vesicle-associated membrane protein-associated protein of 33 kDa (hVAP-33). In vitro binding assay and in vivo coimmunoprecipitation studies confirmed the interaction between hVAP-33 and NS5A. Interestingly, hVAP-33 was also shown to interact with NS5B, the viral RNA-dependent RNA polymerase. NS5A and NS5B bind to different domains of hVAP-33: NS5A binds to the C-terminus, whereas NS5B binds to the N-terminus of hVAP-33. Immunofluorescent staining showed a significant colocalization of hVAP-33 with both NS5A and NS5B proteins. hVAP-33 contains a coiled-coil domain followed by a membrane-spanning domain at its C-terminus. Cell fractionation analysis revealed that hVAP-33 is predominantly associated with the ER, the Golgi complex, and the prelysosomal membrane, consistent with its potential role in intracellular membrane trafficking. These interactions provide a mechanism for membrane association of the HCV RNA replication complex and further suggest that NS5A is a part of the viral RNA replication complex.

Screening men for abdominal aortic aneurysm: 10 year mortality and cost effectiveness results from the randomised Multicentre Aneurysm Screening Study

OBJECTIVES

To assess whether the mortality benefit from screening men aged 65-74 for abdominal aortic aneurysm decreases over time, and to estimate the long term cost effectiveness of screening.

DESIGN

Randomised trial with 10 years of follow-up.

SETTING

Four centres in the UK. Screening and surveillance was delivered mainly in primary care settings, with follow-up and surgery offered in hospitals.

PARTICIPANTS

Population based sample of 67 770 men aged 65-74.

INTERVENTIONS

Participants were individually allocated to invitation to ultrasound screening (invited group) or to a control group not offered screening. Patients with an abdominal aortic aneurysm detected at screening underwent surveillance and were offered surgery if they met predefined criteria.

MAIN OUTCOME MEASURES

Mortality and costs related to abdominal aortic aneurysm, and cost per life year gained.

RESULTS

Over 10 years 155 deaths related to abdominal aortic aneurysm (absolute risk 0.46%) occurred in the invited group and 296 (0.87%) in the control group (relative risk reduction 48%, 95% confidence interval 37% to 57%). The degree of benefit seen in earlier years of follow-up was maintained in later years. Based on the 10 year trial data, the incremental cost per man invited to screening was pound100 (95% confidence interval pound82 to pound118), leading to an incremental cost effectiveness ratio of pound7600 ( pound5100 to pound13,000) per life year gained. However, the incidence of ruptured abdominal aortic aneurysms in those originally screened as normal increased noticeably after eight years.

CONCLUSIONS

The mortality benefit of screening men aged 65-74 for abdominal aortic aneurysm is maintained up to 10 years and cost effectiveness becomes more favourable over time. To maximise the benefit from a screening programme, emphasis should be placed on achieving a high initial rate of attendance and good adherence to clinical follow-up, preventing delays in undertaking surgery, and maintaining a low operative mortality after elective surgery. On the basis of current evidence, rescreening of those originally screened as normal is not justified. Trial registration Current Controlled Trials ISRCTN37381646.

Mutation of the CDKN2A 5' UTR creates an aberrant initiation codon and predisposes to melanoma

Approximately 8-12% of melanoma is inherited in an autosomal dominant fashion with variable penetrance. A chromosome 9p21 locus has been linked to this disease in 50-80% of affected families. CDKN2A (also known as P16, INK4, p16INK4A and MTS1) is allelic to this locus and encodes a cdk4/cdk6 kinase inhibitor that constrains cells from progressing through the G1 restriction point. Although germline CDKN2A coding mutations cosegregate with melanoma in 25-60% of families predisposed to the disease, there remains a number of mutation-negative families that demonstrate linkage of inherited melanoma to 9p21 markers. We show here that a subset of these kindreds possess a G-->T transversion at base -34 of CDKN2A, designated G-34T. This mutation gives rise to a novel AUG translation initiation codon that decreases translation from the wild-type AUG. The G-34T mutation is not seen in controls, segregates with melanoma in families and, on the basis of haplotyping studies, probably arose from a common founder in the United Kingdom. Characterization of this and other CDKN2A non-coding mutations should have an impact on current efforts to identify susceptible melanoma-prone families and individuals.

Role of tumor-associated gangliosides in cancer progression

Neuroectodermic tumors can mostly be characterized by the presence of tumor-associated glycosphingolipid antigens, such as gangliosides, defined by monoclonal antibodies. Recently, cumulative evidence indicates that gangliosides modify the biological effects of several trophic factors, in vitro and in vivo, as well as the mitogenic signaling cascade that these factors generate. The functional roles of gangliosides in tumor progression can be revisited: (i) ganglioside antigens on the cell surface, or shed from the cells, act as immunosuppressors, as typically observed for the suppression of cytotoxic T cells and dendritic cells, (ii) certain gangliosides, such as GD3 or GM2, promote tumor-associated angiogenesis, (iii) gangliosides strongly regulate cell adhesion/motility and thus initiate tumor metastasis, (iv) ganglioside antigens are directly connected with transducer molecules in microdomains to initiate adhesion coupled with signaling, and (v) ganglioside antigens and their catabolites are modulators of signal transduction through interaction with tyrosine kinases associated with growth factor receptors or other protein kinases. Given the potential importance of these sialylated gangliosides and their modulating biological behavior in vivo, further studies on the role of gangliosides are warranted.

Requirement of human immunodeficiency virus type 1 nef for in vivo replication and pathogenicity

The role of human immunodeficiency virus type 1 (HIV-1) accessory genes in pathogenesis has remained unclear because of the lack of a suitable in vivo model. The most controversial of these genes is nef. We investigated the requirement for Nef for in vivo replication and pathogenicity of two isolates of HIV-1 (HIV-1JR-CSF and HIV-1NL4-3) in human fetal thymus and liver implants in severe combined immunodeficient mice. HIV-1JR-CSF and HIV-1NL4-3 differ in their in vitro phenotypes in that HIV-1JR-CSF does not induce syncytia and is relatively noncytopathic, while HIV-1NL4-3 is highly cytopathic and readily induces syncytia. The nef mutants of both isolates grew with kinetics similar to those of parental virus strains in stimulated peripheral blood lymphocytes but demonstrated attenuated growth properties in vivo. HIV-1NL4-3 induced severe depletion of human thymocytes within 6 weeks of infection, whereas its nef mutant did not. Thus, HIV-1 Nef is required for efficient in vivo viral replication and pathogenicity.

Superconductivity at 52.5 k in the lanthanum-barium-copper-oxide system

A superconducting transition with an onset temperature of 52.5 K has been observed under hydrostatic pressure in compounds with nominal compositions given by (La(0.9)Ba(0.1))(2) CuO4-Y. Possible causes for the high-temperature superconductivity are discussed.

Isolation and molecular cloning of insulin-like growth factor-binding protein-6

Insulin-like growth factors (IGFs) together with their binding proteins (BPs) are potential regulators of folliculogenesis in mammalian ovary. To identify the various species of IGFBPs present in the ovary, we have undertaken a comprehensive purification scheme using gel filtration, ligand-affinity chromatography, and several steps of reverse phase HPLC to isolate all of the BPs in pig ovarian follicular fluid. Our effort yielded five distinct IGFBPs, and upon analysis, they were found to correspond to the previously identified human and rat IGFBP-2, -3, -4, -5, and -6. IGFBP-1 was not found in the pig ovarian follicular fluid under our experimental procedure. Of the six known classes of IGFBPs, the complete primary structures of the first five have been determined, but not IGFBP-6. Using amino acid sequence information from a tryptic fragment of pig IGFBP-6 to prepare a probe, cDNA clones encoding rat and human IGFBP-6 have been isolated and characterized. The deduced amino acid sequence revealed that rat IGFBP-6 contains 201 amino acids with a calculated mol wt of 21,461, while the human homolog contains 216 amino acids with a calculated mol wt of 22,847. In addition, a distinctive feature of human and rat IGFBP-6 is that they lack, respectively, two and four of the 18 homologous cysteines that are present in all other five IGFBPs. The missing cysteines in IGFBP-6 resulted in the absence of the invariant Gly-Cys-Gly-Cys-Cys sequence in the amino-terminal region of the molecule. Human IGFBP-6 possesses a single Asn-linked glycosylation site near the carboxyl-terminal, whereas no potential Asn-linked glycosylation sites are present in the rat sequence. A single 1.3-kilobase IGFBP-6 mRNA was detected by Northern analysis in all rat tissues examined, including testis, intestine, adrenal, kidney, stomach, spleen, heart, lung, brain, and liver, indicating that this BP is a ubiquitous protein. The chromosome location of the IGFBP-6 gene in human has been determined using polymerase chain reaction on somatic cell hybrid DNAs of human and hamster, and the results showed that it is located on chromosome 12.

Automatic liver segmentation technique for three-dimensional visualization of CT data

PURPOSE

To develop a system for automatic segmentation of the liver from computed tomographic (CT) scans of the abdomen for three-dimensional volume-rendering displays.

MATERIALS AND METHODS

An automated liver segmentation system was developed, which combined domain knowledge with analysis of a global histogram, morphologic operators, and the parametrically deformable contour model. Boundaries of the thresholded liver volume were modified section-by-section by exploiting information from adjacent sections. These boundaries were refined by optimization of the parametrically deformable contour model. Volume-rendered images were created by using the boundaries to exclude tissues outside the liver. The system was tested on CT data sets from 10 cases of potentially resectable hepatic neoplasm.

RESULTS

Of the 401 sections in the 10 cases, 53 sections (13.2%) required user modifications during segmentation. The utility of the three-dimensional-rendered images with use of these liver boundaries was judged by a radiologist as being comparable to that of three-dimensional images created with manual editing. Twenty-eight of the sections were deemed imperfect by the radiologist and might need further modifications.

CONCLUSION

An effective technique for automatic segmentation of the liver from CT images has been developed. This technique promises to save time and simplify the creation of three-dimensional liver images by minimizing operator intervention.

Fifteen-year follow-up of a randomized clinical trial of ultrasonographic screening for abdominal aortic aneurysms

BACKGROUND

Long-term benefits of screening for abdominal aortic aneurysm (AAA) are uncertain. These are the final results of a randomized controlled screening trial for AAA in men, updating those reported previously. Benefit and compliance over a median 15-year interval were examined.

METHODS

One group of men were invited for ultrasonographic AAA screening, and another group, who received standard care, acted as controls. A total of 6040 men aged 65-80 years were randomized to one of the two groups. Outcome was monitored in terms of AAA-related events (surgery or death).

RESULTS

In the group invited for screening, AAA-related mortality was reduced by 11 per cent (from 1.8 to 1.6 per cent, hazard ratio 0.89) over the follow-up interval. Screening detected an AAA in 170 patients; 17 of these died from an AAA-related cause, seven of which might have been preventable. The incidence of AAA rupture after an initially normal scan increased after 10 years of follow-up, but was still low overall (0.56 per 1000 person-years).

CONCLUSION

Screening with a single ultrasonography scan still conferred a benefit at 15 years, although the results were not significant for this population size. Fewer than half of the AAA-related deaths in those screened positive could be prevented.

REGISTRATION NUMBER

ISRCTN 00079388 (http://www.controlled-trials.com).

MicroRNA-193a represses c-kit expression and functions as a methylation-silenced tumor suppressor in acute myeloid leukemia

Aberrant activation of c-kit proto-oncogene contributes to abnormal cell proliferation by altering the tyrosine kinase signaling and constitutes a crucial impetus for leukemogenesis. Epigenetic silencing of tumor-suppressive microRNAs (miRNAs) is a key oncogenic mechanism for the activation of oncogenes in tumors. In this study, several miRNAs potentially binding to the 3'-untranslated region of human c-kit mRNA were screened by luciferase reporter assays. Among these miRNAs, miR-193a was embedded in a CpG island and epigenetically repressed by promoter hypermethylation in acute myeloid leukemia (AML) cell lines and primary AML blasts, but not in normal bone marrow cells. Importantly, miR-193a levels were inversely correlated with c-kit levels measured in 9 leukemia cell lines and 27 primary AML samples. Restoring miR-193a expression in AML cells harboring c-kit mutation and/or overexpression, either by synthetic miR-193a transfection or by DNA hypomethylating agent 5-azacytidine (5-aza) treatment, resulted in a significant reduction in c-kit expression at both RNA and protein levels and inhibition of cell growth. The growth-inhibitory activity of miR-193a was associated with apoptosis and granulocytic differentiation. Moreover, 5-aza-induced c-kit reduction could be partially blocked by miR-193a inhibitor, leading to a reversal of antiproliferative and proapoptotic effects of 5-aza. These data reveal a critical role for methylation-repressed miR-193a in myeloid leukemogenesis and the therapeutic promise of upregulating miR-193a expression for c-kit-positive AML.

Short- and potential long-term adverse health outcomes of COVID-19: a rapid review

The coronavirus disease 2019 (COVID-19) pandemic has resulted in millions of patients infected worldwide and indirectly affecting even more individuals through disruption of daily living. Long-term adverse outcomes have been reported with similar diseases from other coronaviruses, namely Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). Emerging evidence suggests that COVID-19 adversely affects different systems in the human body. This review summarizes the current evidence on the short-term adverse health outcomes and assesses the risk of potential long-term adverse outcomes of COVID-19. Major adverse outcomes were found to affect different body systems: immune system (including but not limited to Guillain-Barré syndrome and paediatric inflammatory multisystem syndrome), respiratory system (lung fibrosis and pulmonary thromboembolism), cardiovascular system (cardiomyopathy and coagulopathy), neurological system (sensory dysfunction and stroke), as well as cutaneous and gastrointestinal manifestations, impaired hepatic and renal function. Mental health in patients with COVID-19 was also found to be adversely affected. The burden of caring for COVID-19 survivors is likely to be huge. Therefore, it is important for policy makers to develop comprehensive strategies in providing resources and capacity in the healthcare system. Future epidemiological studies are needed to further investigate the long-term impact on COVID-19 survivors.