[Current management of acute Stanford type A aortic dissection complicated with mesenteric malperfusion]

The management of acute type A aortic dissection (aTAAD) with mesenteric malperfusion (MMP) is quite challenging as it is often associated with high mortality and poor outcomes, and an optimal treatment strategy is lack of consensus for this critically ill condition. Emergent open surgical repair of the ascending aorta is a life-saving operation and remains the standard of care for aTAAD with MMP, but is associated with a high rate of mortality. In recent years, reperfusion of superior mesenteric artery (SMA) by endovascular repair as the first treatment strategy in the treatment of aTAAD with MMP has been concerned and reported. Only endovascular repair and conservative medical treatment are also introduced in few cases with poor outcomes. There are many urgent issues that need to be addressed in current strategies. The optimal management strategies remain controversial, and further investigation and research are needed. These issues were addressed in this article.

[Advances in three-dimensional tumor models for colorectal cancer]

Conventional tumor culture models include two-dimensional tumor cell cultures and xenograft models. The former has disadvantages including lack of tumor heterogeneity and poor clinical relevance, while the latter are limited by the slow growth, low engraftment successful rate, and high cost. In recent years, in vitro three-dimensional (3D) tumor models have emerged as the tool to better recapitulate the spatial structure and the in vivo environment of tumors. In addition, they preserve the pathological and genetic features of tumor cells and reflect the complex intracellular and extracellular interactions of tumors, which have become a powerful tool for investigating the tumor mechanism, drug screening, and personalized cancer treatment. 3D tumor model technologies such as spheroids, organoids, and microfluidic devices are maturing. Application of new technologies such as co-culture, 3D bioprinting, and air-liquid interface has further improved the clinical relevance of the models. Some models recapitulate the tumor microenvironment, and some can even reconstitute endogenous immune components and microvasculature. In recent years, some scholars have combined xenograft models with organoid technology to develop matched in vivo/in vitro model biobanks, giving full play to the advantages of the two technologies, and providing an ideal research platform for individualized precision therapy for specific molecular targets in certain subtypes of tumors. So far, the above technologies have been widely applied in the field of colorectal cancer research. Our research team is currently studying upon the application of patient-derived tumor cell-like clusters, a self-assembly 3D tumor model, in guiding the selection of postoperative chemotherapy regimens for colorectal cancer. A high modeling success rate and satisfactory results in the drug screening experiments have been achieved. There is no doubt that with the advancement of related technologies, 3D tumor models will play an increasingly important role in the research and clinical practice of colorectal cancer.

Infection control measures for public transportation derived from the flow dynamics of obstructed cough jet

During the COVID-19 pandemic, WHO and CDC suggest people stay 1 m and 1.8 m away from others, respectively. Keeping social distance can avoid close contact and mitigate infection spread. Many researchers suspect that suggested distances are not enough because aerosols can spread up to 7-8 m away. Despite the debate on social distance, these social distances rely on unobstructed respiratory activities such as coughing and sneezing. Differently, in this work, we focused on the most common but less studied aerosol spread from an obstructed cough. The flow dynamics of a cough jet blocked by the backrest and gasper jet in a cabin environment was characterized by the particle image velocimetry (PIV) technique. It was proved that the backrest and the gasper jet can prevent the front passenger from droplet spray in public transportation where maintaining social distance was difficult. A model was developed to describe the cough jet trajectory due to the gasper jet, which matched well with PIV results. It was found that buoyancy and inside droplets almost do not affect the short-range cough jet trajectory. Infection control measures were suggested for public transportation, including using backrest/gasper jet, installing localized exhaust, and surface cleaning of the backrest.

[The current status and prospect of catheter-based treatment of ascending aorta and aortic root diseases]

In recent years, the endovascular procedures has considerably evolved in concepts, technologies, materials and devices on cardiovascular surgery, and influenced the development and the future direction of cardiovascular surgery technology. Endovascular aorta repair is well recognized as the optimal therapy for patients presenting with acute or chronic pathology of distal aortic arch, descending aorta and thoraco-abdominal aorta. The use of catheter-based endovascular repair in the ascending aorta pathology including aneurysms, pseudoaneurysms, penetrating aortic ulcers and acute or chronic Stanford type A aortic dissection has been concerned and reported. Comparing to the open surgical procedures for ascending aorta and aortic root disease with high perioperative mortality and morbidity, the catheter-based endovascular repair has minimally invasive, expanding the alternative treatment of ascending aorta disease, especially for patients with high-risk profiles. However, due to the complex anatomy and functional properties, materials and devices, the use of this technique in ascending aorta and aortic root is still questionable. In addition, the long-term and reliable clinical research results is still inadequate, and the safety and effectiveness need further research.

[Clinical analysis of 30 cases of traumatic aortic injury]

Objective: To examine the clinical treatment methods and short- and mid-term results of traumatic aortic injury (TAI). Methods: The clinical data of 30 patients suffering from TAI who were admitted to Department of Cardiothoracic Surgery, General Hospital of Eastern Theater Command from January 2010 to December 2018 were summarized and analyzed retrospectively. All patients were diagnosed as TAI by aortic CT angiography. There were 20 males and 10 females, aging (46.4±15.2) years (range: 17 to 76 years). One patient was diagnosed as extensive intramural hematoma (IMH). The other 29 cases had aortic intimal injury, and the primary intimal tear of all these patients was located in the isthmus of descending aorta. There were 2 cases of ulcer-like changes combined with IMH, and 27 cases of traumatic aortic dissection (TAD) including 23 cases of localized TAD and 4 cases of extensive TAD. Endovascular repair, artificial vascular replacement or conservative treatment were performed according to the patient's specific condition. The patients were followed up in outpatient or by telephone. The clinical data of all the patients of the in-hospital treatment and during follow-up period was analyzed retrospectively. Results: One patient with IMH was treated conservatively. Surgical intervention was performed in 29 cases with intimal injury, of which 14 cases underwent emergency surgery on the day of admission or the next day, and 15 cases underwent elective surgery. Twenty-seven cases underwent thoracic endovascular aortic repair (TEVAR), and 2 cases underwent artificial vascular replacement. Nine cases suffered combined operations in early or late stage. All patients were cured and discharged with in-hospital stay of (13.2±5.4) days (range: 7 to 30 days). There was no in-hospital death. Two patients underwent tracheotomy, and the rest had no serious complications. Up to the last follow-up in June 2019, 4 patients were lost to follow-up, and the remaining 26 patients were followed up for (50.6±34.1) months (range: 6 to 112 months) and survived healthily without new aortic events. Conclusions: Most of TAD cases are ascribed to Stanford type B aortic dissection, and a satisfactory short-term and mid-term result can be achieved by emergency TEVAR in most patients. Some patients can achieve good long-term results by open surgery with artificial vascular replacement.

[The pH-Sensitive Potassium Channel TASK-1 Is a Chemosensor for Central Respiratory Regulation in Rats]

TWIK-related acid-sensitive potassium channel-1 (TASK-1) is a "leak" potassium channel sensitive to extracellular protons. It contributes to setting the resting potential in mammalian neurons. TASK-1 channels are widely expressed in respiratory-related neurons in the central nervous system. Inhibition of TASK-1 by extracellular acidosis can depolarize and increase the excitability of these cells. Here we describe the distribution of TASK-1 in the rat brainstem and show that TASK-1 mRNAs are present in respiratory-related nuclei in the ventrolateral medulla, which have been proposed as neural substrates for central chemo-reception in rats. After inhalation of 8% CO2 for 30 and 60 min, TASK-1 mRNA levels in positive-expression neurons were remarkably upregulated. Injection of the TASK-1 blocker anandamide (AEA) into the rat lateral cerebral ventricle, showed a significant excitement of respiratory at 10 min posttreatment, with a marked decrease in inspiratory and expiratory durations and an increased frequency of respiration. We suggest that TASK-1 channel may serve as a chemosensor for in central respiration and may contribute to pH-sensitive respiratory effects. TASK-1 channel might be an attractive candidate for sensing H^(+)/CO2 in several respiratory-related nuclei in the brainstem. It is likely that TASK-1 participates in pH-sensitive chemical regulation in the respiratory center under physiological and pathological conditions.

[A multicenter cross-sectional study on chronic critical illness and surgery-related chronic critical illness in China]

Objective: To understand the prevalence, diagnosis and treatment of chronic critical illness (CCI) in China. Methods: The clinical data of 472 adult patients admitted to ICU in 53 hospitals, including basic information, disease-related data, nutrition program, etc., were collected on May 10, 2019, by means of multi-center cross-sectional study. If surgical intervention was needed or the occurrence of the disease was directly related to the surgery, ICU patients were regarded as surgical ICU cases (n=211). In this study, the diagnostic criteria for CCI were: (1) admission to ICU >14 days;(2) combined with persistent organ dysfunction. The prevalence,distribution and treatment of CCI and surgery-related CCI were recorded and analyzed. The Mann-Whitney U test, chi-square test or Fisher exact test were used for comparative analysis. Results: Among the 472 ICU patients from 53 hospitals, 326 were male (69.1%) and 146 were female (30.9%). The prevalence of CCI was 30.7% (145/472). Among 211 surgery-related ICU patients, 57 developed CCI with a prevalence of 27.0%. As compared to non-CCI patients, higher APACHE II score [median (IQR) 13.5 (10.0, 18.3) vs. 11.0 (7.0, 16.0), U=2970.000, P=0.007], higher Charlson comorbidity index [median (IQR) 4.0 (2.0, 7.0) vs. 3.0 (1.0, 5.0), U= 3570.000, P=0.036] and higher ratio of breath dysfunction [68.4% (39/57) vs. 48.1% (74/154), χ(2)=6.939, P=0.008] and renal dysfunction [42.1% (24/57) vs. 18.2% (28/154), χ(2)=12.821, P<0.001] were found in surgery-related CCI patients. While SOFA score, Glasgow coma score and other visceral function were not significantly different between surgery-related CCI and non-CCI patients (all P>0.05). NUTRIC score showed that surgery-related CCI patients had higher nutritional risk [43.9% (25/57) vs. 26.6%(41/154), U=5.750, P=0.016] and higher ratio of mechanical ventilation [66.7% (38/57) vs. 52.3% (79/154), χ(2)=3.977, P=0.046] than non-CCI patients. On the survey day, the daily caloric requirements of 50.2% (106/211) of surgery-related ICU patients were calculated according to the standard adult caloric intake index (104.6 to 125.5 kJ·kg(-1)·d(-1), 1 kJ=0.239 kcal), and the daily caloric requirements of 46.4% (98/211) of patients were calculated by physicians according to the severity of the patient's condition. 60.2% (127/211) of nutritional support therapy was enteral nutrition (including a combination of enteral and parenteral nutrition), while the remaining patients received parenteral nutrition (24.6%, 52/211), simple glucose infusion (9.0%, 19/211), or oral diet (6.2%, 13/211). The target calorie of CCI group was 104.6 (87.9, 125.5) kJ·kg(-1)·d(-1), and the actual calorie intake accounted for 0.98 (0.80, 1.00) of the target calory. In the non-CCI group, the target calorie was 104.6 (87.9, 125.5) kJ·kg(-1)·d(-1), and the actual calorie consumed accounted for 0.91 (0.66, 1.00) of the target calorie. There was no statistically significant difference between two groups (P=0.248, P=0.150). Conclusion: The prevalence of CCI and surgery-related CCI in ICU is high, along with severe complications, respiratory and renal dysfunction and mechanical ventilation. Surgical patients admitted to ICU are at high nutritional risk, and active and correct nutritional support is essential for such patients.

Chitosan films promote formation of olfactory neurospheres and differentiation of olfactory receptor neurons

BACKGROUND

Olfactory dysfunction significantly impairs the life quality of patients. Therefore, a model needs to be developed for anosmia. Chitosan is a biodegradable natural polysaccharide that has been widely studied for regenerative purposes in the nervous system. However, whether chitosan promotes differentiation of olfactory receptor neurons or regulates formation of neurospheres in the olfactory system remains unexplored.

METHODOLOGY

Olfactory neuroepithelial cells were isolated from embryonic wistar rats on day 17, and cultured on controls and chitosan films for 12 days. The effects of treatment were assessed using immunocytochemistry, quantitative polymerase chain reaction and western blots following culturing. The substrate of poly-L-lysine-co-laminin was adopted as a control.

RESULTS

In contrast to the flat layer on controls, olfactory neuroepithelial cells form olfactory neurospheres on chitosan films with steadily increasing diameter. The olfactory neurospheres contain basal cells, as well as immature and mature olfactory receptor neurons. The expression level of olfactory marker protein is higher on chitosan films than those on controls in gene and protein levels, and the olfactory transduction elements also express a similar trend. Mature olfactory receptor neurons are found predominantly at the periphery of the olfactory neurospheres.

CONCLUSIONS

Chitosan films not only facilitate formation of olfactory neurospheres, but also promote differentiation of olfactory receptor neurons. Chitosan is a potential biomaterial to establish an in vitro culture model to treat olfactory dysfunction in future.

[Endovascular repair of primary retrograde Stanford type A aortic dissection]

Objective: To summarize the short- and mid-term results on endovascular repair of primary retrograde Stanford type A aortic dissection with an entry tear in distal aortic arch or descending aorta. Methods: Between December 2009 and December 2014, 21 male patients of primary retrograde Stanford type A aortic dissection with a mean age of (52±9) years received endovascular repair in Department of Cardiothoracic Surgery, Jinling Hospital. Among the 21 cases, 17 patients were presented as ascending aortic intramural hematoma, 4 patients as active blood flow in false lumen and partial thrombosis, 8 patients as ulcer on descending aorta combined intramural hematoma in descending aorta, and 13 patients as typical dissection changes. All patients received endovascular stent-graft repair successfully, with 15 cases in acute phase and 6 cases in chronic phase. Results: Cone stent was implanted in 13 cases, while straight stent in 8 cases, including 1 case of left common carotid-left subclavian artery bypass surgery and 1 case of restrictive bare-metal stent implantation. No perioperative stroke, paraplegia, stent fracture or displacement, limbs or abdominal organ ischemia or other severe complications occured, except for tracheotomy in 2 patients. Active blood flow in ascending aorta or aortic arch disappeared, and intramural hematoma started being absorbed on CT angiography images before discharge. All patients were alive during follow-up (6 to 72 months), and intramural hematoma in ascending aorta and aortic arch was absorbed thoroughly. Type Ⅰ endoleak and ulcer expansion were found in 1 patient, and type Ⅳ endoleak in distal stent was found in another one patient. Secondary ascending aortic dissection was found in 1 case two years later, which was cured by hybrid procedure with cardiopulmonary bypass. Conclusion: Endovascular repair of primary retrograde Stanford type A aortic dissection was safe and effective, which correlated with favorable short- and mid-term results.

Establishment of reference sequences of hepatitis B virus genotype C subgenotypes

Hepatitis B virus genotype C (HBV/C) has the largest number of subgenotypes (C1-C16) that vary with geography and isolates. HBV/C prevails in Southeast Asia (C1, C5-C16), East Asia (C2), Oceania (C3), and Australia (C4). Suitable reference strains for different subgenotypes could greatly facilitate research into HBV/C, but unfortunately they are scarce. We retrieved 974 HBV/C full-length sequences from the GenBank database and subgenotyped them by phylogenetic analysis. Reference sequences of each subgenotype from different locations were established with the most frequent nucleotide present at each position of the isolates that belonged to the same subgenotype. The reference sequences of subgenotypes C1, C2, C5, and C6 have been constructed and deposited in GenBank (KM999990-KM999993). The homology between the reference sequences and almost all the isolates belonging to the corresponding subgenotype was higher than 96%. Similarly, bootstrap values in phylogenetic trees supported clustering of reference strains with isolates belonging to the same subgenotypes. Moreover, both homology and phylogeny analyses showed that reference sequences had significant heterogeneity with isolates from other genotypes and subgenotypes. Sequence analysis further revealed that the mutation rate in the basal core promoter (BCP) region was extremely high in HBV/C2, relatively high in HBV/C1, but lower in HBV/C5 and HBV/C6. Mutations in the pre-core (Pre-C) region were common in HBV/C but the mutation rate was lower than in the BCP. HBV/ C5 has the oldest ancestral age, followed by C6, which is much more ancient than C1 and C2. This study successfully established references for HBV/C subgenotypes.

Genomic survey and gene expression analysis of the VDAC gene family in rice

The voltage-dependent anion channel (VDAC), also known as a mitochondrial porin, plays an important role in the regulation of metabolic and energetic functions of mitochondria, as well as in mitochondria-mediated apoptosis. Cytoplasmic male sterility (CMS) is of major economic importance for commercial hybrid production and a research model for the interaction be-tween nuclear and cytoplasmic genomes. Recent research has revealed that CMS is associated with programmed cell death. Here, we used the Honglian (HL)-CMS line of rice (Oryza sativa) as material to investigate the association of O. sativa VDAC (OsVDAC) expression to CMS. Eight VDACs were extracted from rice in this study. Bioinformatic analysis of the rice VDACs was conducted at the DNA, cDNA, and protein level. Expression patterns of OsVDACs were analyzed in different organs and during different stages of pollen development using sterile line YuetaiA (YTA), and its maintainer line YuetaiB (YTB). Differential expression of OsVDACs between YTA and YTB was observed, suggesting that VDACs may be involved in the formation of HL-CMS.

Prolonged use of fondaparinux for perioperative bridging: a case report of a patient with mechanical heart valve and heparin-induced thrombocytopenia

WHAT IS KNOWN AND OBJECTIVES

Current guidelines provide no recommendations on perioperative bridging for patients after mechanical heart valve replacement (MHVR) who also have a history of heparin-induced thrombocytopenia (HIT). We present a successful case of prolonged bridging with fondaparinux in a 69-year-old Chinese woman.

CASE SUMMARY

The patient presented to our department with the aim for radical resection of oesophageal cancer. Fondaparinux has been administered alone at 2·5 mg subcutaneously once daily for 24 days during the interruption of warfarin perioperatively. There were no signs or symptoms of thromboembolic or bleeding throughout and after her hospitalization.

WHAT IS NEW AND CONCLUSION

Fondaparinux may offer an option for management of the patients with MHVR who cannot use heparin products, but further clinical investigations are warranted.

MicroRNA-29a promotes apoptosis of monocytes by targeting STAT3 during sepsis

Sepsis is a major cause of morbidity and mortality in critically ill patients. The sepsis syndrome results from a dysregulated inflammatory response to infection that leads to multiple-organ failure, but the underlying mechanisms remain poorly understood. More and more reports show that microRNAs (miRNAs) play an important role in sepsis. In the progression of this syndrome, cells change their behavior in response to cytokines stimulated by sepsis, such as interleukin-10 (IL-10). IL-10 can activate JAK2-STAT3 in the cells to protect them from damage. miR-29a is a potential miRNA directly targeting STAT3. In this study, we investigate the role of miR-29a in targeting STAT3 during sepsis. When cells were treated with IL-10, STAT3 was activated in monocytes, as determined using western blotting. It was verified that STAT3 was a new target gene of miR-29a. miR-29a could inhibit IL-10-induced cytokine release by targeting JAK-STAT3 in monocytes. In conclusion, this study demonstrates for the first time that miR-29a inhibits STAT3 in human monocytes during sepsis.

Three-dimensional analysis of the surface registration accuracy of electromagnetic navigation systems in live endoscopic sinus surgery

BACKGROUND

Studies on the performance of surface registration with electromagnetic tracking systems are lacking in both live surgery and the laboratory setting. This study presents the efficiency in time of the system preparation as well as the navigational accuracy of surface registration using electromagnetic tracking systems.

METHODOLOGY

Forty patients with bilateral chronic paranasal pansinusitis underwent endoscopic sinus surgery after undergoing sinus computed tomography scans. The surgeries were performed under electromagnetic navigation guidance after the surface registration had been carried out on all of the patients. The intraoperative measurements indicate the time taken for equipment set-up, surface registration and surgical procedure, as well as the degree of navigation error along 3 axes.

RESULTS

The time taken for equipment set-up, surface registration and the surgical procedure was 179 +- 23 seconds, 39 +- 4.8 seconds and 114 +- 36 minutes, respectively. A comparison of the navigation error along the 3 axes showed that the deviation in the medial-lateral direction was significantly less than that in the anterior-posterior and cranial-caudal directions.

CONCLUSION

The procedures of equipment set-up and surface registration in electromagnetic navigation tracking are efficient, convenient and easy to manipulate. The system accuracy is within the acceptable ranges, especially on the medial-lateral axis.

Processing of an ultrafine-grained titanium by high-pressure torsion: an evaluation of the wear properties with and without a TiN coating

A commercial purity (CP) Grade 2 Ti was processed by high-pressure torsion (HPT) using an imposed pressure of 3.0GPa at room temperature. The HPT processing reduced the grain size from ∼8.6 μm in the as-received state to ultra-fine grains (UFG) of ∼130 nm after HPT. Tensile testing showed the HPT-processed Ti exhibited a good combination of high ultimate tensile strength (∼940 MPa) and a reasonable elongation to failure (∼23%). Physical vapour deposition was used to deposit TiN coatings, with a thickness of 2.5 μm, on Ti samples both with and without HPT processing. Scratch tests showed the TiN coating on UFG Ti had a critical failure load of ∼22.5 N whereas the load was only ∼12.7 N for the coarse-grained Ti. The difference is explained using a simple composite hardness model. Wear tests demonstrated an improved wear resistance of TiN coating when using UFG Ti as the substrate. The results suggest that CP Ti processed by HPT and subsequently coated with TiN provides a potentially important material for use in bio-implants.

Prokaryotic expression of a novel mouse pro-apoptosis protein PNAS-4 and application of its polyclonal antibodies

Mouse PNAS-4 (mPNAS-4) has 96% identity with human PNAS-4 (hPNAS-4) in primary sequence and has been reported to be involved in the apoptotic response to DNA damage. However, there have been no studies reported of the biological functions of mPNAS-4. In studies conducted by our group (unpublished data), it was interesting to note that overexpression of mPNAS-4 promoted apoptotic death in Lewis lung carcinoma cells (LL2) and colon carcinoma cells (CT26) of mice both in vitro and in vivo. In our studies, mPNAS-4 was cloned into the pGEX-6P-1 vector with GST tag at N-terminal in Escherichia coli strain BL21(DE3). The soluble and insoluble expression of recombinant protein mPNAS-4 (rmPNAS-4) was temperature-dependent. The majority of rmPNAS-4 was insoluble at 37 degrees C, while it was almost exclusively expressed in soluble form at 20 degrees C. The soluble rmPNAS-4 was purified by one-step affinity purification, using a glutathione Sepharose 4B column. The rmPNAS-4 protein was further identified by electrospray ionization-mass spectrometry analysis. The search parameters of the parent and fragment mass error tolerance were set at 0.1 and 0.05 kDa, respectively, and the sequence coverage of search result was 28%. The purified rmPNAS-4 was further used as immunogen to raise polyclonal antibodies in New Zealand white rabbit, which were suitable to detect both the recombinant and the endogenous mPNAS-4 in mouse brain tissue and LL2 cells after immunoblotting and/or immunostaining. The purified rmPNAS-4 and our prepared anti-mPNAS-4 polyclonal antibodies may provide useful tools for future biological function studies for mPNAS.

Higher Bcl-2 levels decrease staphylococcal superantigen-induced apoptosis of CD4+ T cells in atopic dermatitis

BACKGROUND

Staphylococcal superantigens (SsAgs) contribute to the persistence of allergic skin inflammation in atopic dermatitis (AD). The aims of this study were to (1) determine whether there are differences between AD patients and healthy subjects in SsAg-induced caspase-3 activation and SsAg-induced changes of anti-apoptotic protein Bcl-2 and Bcl-2 mRNA levels of CD4+ T cells; (2) investigate the effect of interleukin (IL)-4 on SsAg-induced caspase-3 activation and SsAg-induced changes of Bcl-2 and Bcl-2 mRNA levels of CD4+ T cells.

METHODS

Using immunofluorescence staining followed by flow cytometric analysis and real-time PCR, we analyzed peripheral blood mononuclear cells with or without staphylococcal enterotoxin B (SEB) stimulation in the presence or absence of recombinant IL-4 or anti-IL-4 neutralizing antibodies in 16 AD patients and 14 healthy subjects.

RESULTS

SEB-reactive (TCRVbeta3+, Vbeta12+, and Vbeta17+) CD4+ T cells from AD patients were more resistant to SEB-induced caspase-3 activation and SEB-induced decrease of Bcl-2 and Bcl-2 mRNA than those from healthy subjects. Exogenously added IL-4 inhibited SEB-induced caspase-3 activation and SEB-induced decrease of Bcl-2 and Bcl-2 mRNA in SEB-reactive CD4+ T cells from healthy subjects. Inhibition of endogenous IL-4 by using anti-IL-4 neutralizing antibodies up-regulated SEB-induced caspase-3 activation and SEB-induced decrease of Bcl-2 and Bcl-2 mRNA in SEB-reactive CD4+ T cells from AD patients.

CONCLUSIONS

Following SsAg stimulation, IL-4 produced by T cells in AD patients down-regulates SsAg-induced caspase-3 activation and apoptosis of CD4+ T cells through inhibiting the decrease of Bcl-2. This may impair deletion of SsAg-activated T cells and resolution of allergic skin inflammation.

Novel method for correction of x-ray fluoroscopic image

X-ray fluoroscopic images have been widely used in orthopedic surgery. Unfortunately, the inherent distortion deteriorates the quality of fluoroscopic image. To avoid the discontinuities of local correction techniques and achieve good accuracy in present global correction method, a novel approach for distortion correction is proposed which allows good image quality in relatively acceptable time by combining both global and local methods, and a new local interpolation method is also proposed. Computer simulation and experimental test on fluoroscopic image have been carried out.

A calcium-independent phospholipase activity insensitive to bromoenol lactone mediates arachidonic acid release by lindane in rat myometrial cells

Arachidonic acid release is an important regulatory component of uterine contraction and parturition, and previous studies showed that lindane stimulates arachidonic acid release from myometrium. The present study partially characterized the enzyme activity responsible for lindane-induced arachidonic acid release in myometrial cells. Lindane released arachidonic acid from cultured rat myometrial cells in concentration- and time-dependent manners. This release was primarily from phosphatidylcholine and phosphatidylinositol, and was independent of intracellular and extracellular calcium. In cells prelabeled with [3H]arachidonic acid, 85% of radiolabel was recovered as free arachidonate and only 5% was recovered as eicosanoids. Pretreatment with the antioxidants Cu, Zn-superoxide dismutase, alpha-tocopherol or Trolox did not significantly modify lindane-induced arachidonic acid release. Pretreatment of cells with the phosphatidylcholine-specific phospholipase C inhibitor D609, phosphatidylinositol-specific phospholipase C inhibitor ET-18-OCH3, or an interrupter of the phospholipase D pathway (ethanol) did not suppress lindane-induced arachidonic acid release. Although these results are consistent with calcium-independent phospholipase A2 activation by lindane, the calcium-independent phospholipase A2 inhibitor bromoenol lactone failed to inhibit lindane-induced arachidonic acid release in myometrial cells, even though bromoenol lactone effectively blocked arachidonic acid release in neutrophils. These results suggest that myometrial cells express a novel, previously unidentified phospholipase that is arachidonate-specific, calcium-independent, insensitive to bromoenol lactone, insensitive to reactive oxygen species activation, shows substrate preference for phosphatidylcholine and phosphatidylinositol, and is stimulated by lindane. Moreover, the data show that the overwhelming majority of arachidonic acid released remains as arachidonate, but that lindane does not significantly inhibit metabolism of arachidonate to eicosanoids.

Synaptotagmin modulation of fusion pore kinetics in regulated exocytosis of dense-core vesicles

In the exocytosis of neurotransmitter, fusion pore opening represents the first instant of fluid contact between the vesicle lumen and extracellular space. The existence of the fusion pore has been established by electrical measurements, but its molecular composition is unknown. The possibility that synaptotagmin regulates fusion pores was investigated with amperometry to monitor exocytosis of single dense-core vesicles. Overexpression of synaptotagmin I prolonged the time from fusion pore opening to dilation, whereas synaptotagmin IV shortened this time. Both synaptotagmin isoforms reduced norepinephrine flux through open fusion pores. Thus, synaptotagmin interacts with fusion pores, possibly by associating with a core complex of membrane proteins and/or lipid.

Increase in cytochrome oxidase activity in regenerating nerve fibers of hemitransected spinal cord in the rat

We explored the possibility of cytochrome oxidase (CO) involvement in spinal cord regeneration in adult rats. The spinal cord was hemitransected at T9. After one month's survival, the animals were deeply anesthetized and perfused. The spinal cord segments including the lesion site were removed and sectioned horizontally for CO histochemistry. Under light microscope, a substantial number of CO-reactive nerve fibers and boutons were identified in the lateral funiculus adjacent to the lesion site. Under electron microscope, moderately to highly CO-reactive mitochondria could be seen within nerve fibers and boutons. Synaptic contacts were identified among them. The increase in CO activity in nerve fibers and boutons may indicate their high-energy demand for synaptic and spontaneous activity following spinal cord hemisection.

[Detection of the wheat salt-tolerant-mutant using PCR-SSCP combining with direct sequenceing]

gf-2.8 is a gene located on the chromosomal homologous group 4, which was reported to have relationship with salt tolerance of wheat. A pair of primers were designed to amplify the coding region of gf-2.8 in the two salt-tolerant mutants and their parents. Agarose gel electrophoresis showed that the 685 bp band was amplified among all the materials. SSCP analysis suggested that 974915 (one of the mutants) was different from the other materials. The sequencing results showed that Jimai 24 and its salt-tolerant mutant 8901-17 had the same sequence as published, which indicated that the mutation site of 8901-17 was not on the gf-2.8 gene. However, there were at least two single base mutations in the gf-2.8 of 974915, one of which caused the alternation of amino acid, this mutation occurred in the conservative region of gf-2.8.

Cellular membrane-binding ability of the C-terminal cytoplasmic domain of human immunodeficiency virus type 1 envelope transmembrane protein gp41

The amphipathic alpha-helices located in the cytoplasmic tail of the envelope (Env) transmembrane glycoprotein gp41 of human immunodeficiency virus type 1 have been implicated in membrane association and cytopathicity. Deletion of the last 12 amino acids in the C terminus of this domain severely impairs infectivity. However, the nature of the involvement of the cytoplasmic tail in Env-membrane interactions in cells and the molecular basis for the defect in infectivity of this mutant virus are still poorly understood. In this study we examined the interaction of the cytoplasmic tail with membranes in living mammalian cells by expressing a recombinant cytoplasmic tail fragment and an Escherichia coli beta-galactosidase/cytoplasmic tail fusion protein, both of them lacking gp120, the gp41 ectodomain, and the transmembrane region. We found through cell fractionation, in vivo membrane flotation, and confocal immunofluorescence studies that the cytoplasmic tail contained determinants to be routed to a perinuclear membrane region in cells. Further mapping showed that each of the three lentivirus lytic peptide (LLP-1, LLP-2, and LLP-3) sequences conferred this cellular membrane-targeting ability. Deletion of the last 12 amino acids from the C terminus abolished the ability of the LLP-1 motif to bind to membranes. High salt extraction, in vitro transcription and translation, and posttranslational membrane binding analyses indicated that the beta-galactosidase/LLP fusion proteins were inserted into membranes via the LLP sequences. Subcellular fractionation and confocal microscopy studies revealed that each of the LLP motifs, acting in a position-independent manner, targeted non-endoplasmic reticulum (ER)-associated beta-galactosidase and enhanced green fluorescence protein to the ER. Our study provides a basis for the involvement of the gp41 cytoplasmic tail during Env maturation and also supports the notion that the membrane apposition of the C-terminal cytoplasmic tail plays a crucial role in virus-host interaction.

Arterial tissue of arsenic, selenium and iron in Blackfoot disease patients

In order to identify arsenic as one of the major factors that cause Blackfoot disease on the southwest coast of Taiwan, an atomic absorption spectrophotometric method was used to determine arsenic, selenium and iron concentrations in the tissue of plantar digital arteries. Samples from 31 patients with Blackfoot disease and 30 controls with road traffic accident or occupational injuries were studied. The results indicate that the arterial tissue from Blackfoot disease patients had higher arsenic concentration (3.06+/-1.42 microg/g) than that from healthy controls (0.59+/-0.28 microg/g). The variability was very large 418% at p<0.001. It was also noted that the concentrations of selenium (1.23+/-0.41 microg/g and 1.05+/-0.13 microg/g in patients and controls respectively; with variability 17.1%) and iron (72.7+/-34.9 microg/g and 35.2+/-16.5 microg/g in patients and controls respectively; with variability 106.5%) were both higher than those of controls. However, only the iron concentration was significantly different (p<0.05).

Genetic parameters of reproductive traits in Brown Tsaiya ducks artificially inseminated with semen from Muscovy drakes

A selection experiment on maximum duration of fertility of Brown Tsaiya ducks after artificial insemination (AI) with pooled Muscovy semen has been conducted since 1992. The Brown Tsaiya ducks were divided into two lines: a control line (T) with no selection and a selected line (S). The traits measured were the number of eggs set that were laid from Days 2 to 15 after one AI (NES), the number of fertile eggs at candling (NEF), the total number of dead embryos (NED), the maximum duration of fertility (MD), and the number of hatched mule ducklings (NEH). The selected trait was NEF. Six generations with a total of 2,127 females were measured. The variance components were estimated for each line in a multiple-trait animal model, using the restricted maximum likelihood (REML) methodology, which yields estimates free of bias caused by selection and inbreeding. Estimates of the heritability and genetic correlation from the two lines were very similar. Heritabilities in the S and T lines, respectively, were 0.14 and 0.10 for NES, 0.30 and 0.26 for NEF, 0.06 and 0.09 for NED, 0.28 and 0.21 for MD, and 0.18 and 0.19 for NEH. High and favorable genetic correlations existed between NEF and MD (0.96 and 0.92), between NEF and NEH (0.86 and 0.91), and between MD and NEH (0.90 and 0.82). The results suggested that selection for NEF could improve the maximum duration of fertility, but it could be useful to check the estimates of genetic parameters in a meat-type female duck.

A plant gene encoding a Myb-like protein that binds telomeric GGTTTAG repeats in vitro

A gene (AtTRP1) encoding a telomeric repeat-binding protein has been isolated from Arabidopsis thaliana. AtTRP1 is a single copy gene located on chromosome 5 of A. thaliana. The protein AtTRP1 encoded by this gene is not only homologous to the Myb DNA-binding motifs of other telomere-binding proteins but also is similar to several initiator-binding proteins in plants. Gel retardation assay revealed that the 115 residues on the C terminus of this protein, including the Myb motif, are sufficient for binding to the double-stranded plant telomeric sequence. The isolated DNA-binding domain of AtTRP1 recognizes each telomeric repeat centered on the sequence GGTTTAG. The almost full-length protein of AtTRP1 does not form any complex at all with the DNA fragments carrying four or fewer GGTTTAG repeats. However, it forms a complex with the sequence (GGTTTAG)(8) more efficiently than with the sequence (GGTTTAG)(5). These data suggest that the minimum length of a telomeric DNA for AtTRP1 binding consists of five GGTTTAG repeats and that the optimal AtTRP1 binding may require eight or more GGTTTAG repeats. It also implies that this protein AtTRP1 may bind in vivo primarily to the ends of plant chromosomes, which consist of long stretches of telomeric repeats.

Renormalization group analysis for thermal turbulent transport

In this study, we continue with our previous renormalization group analysis of incompressible turbulence, aiming at determination of various thermal transport properties. In particular, the temperature field T is considered a passive scalar. The quasinormal approximation is assumed for the statistical correlation between the velocity and temperature fields. A differential argument leads to derivation of the turbulent Prandtl number Pr(t) as a function of the turbulent Peclet Pe(t) number, which in turn depends on the turbulent eddy viscosity nu(t). The functional relationship between Pr(t) and Pe(t) is comparable to that of Yakhot et al. [Int. J. Heat Mass Transf. 30, 15 (1987)] and is in close consistency with direct-numerical-simulation results as well as measured data from experiments. The study proceeds further with limiting the operation of renormalization group analysis, yielding an inhomogeneous ordinary differential equation for an invariant thermal eddy diffusivity sigma. Simplicity of the equation renders itself a closed-form solution of sigma as a function of the wave number k, which, when combined with a modified Batchelor's energy spectrum for the passive temperature T, facilitates determination of the Batchelor constant C(B) and a parallel Smagorinsky model and the model constant C(P) for thermal turbulent energy transport.

Assembly and release of human immunodeficiency virus type 1 Gag proteins containing tandem repeats of the matrix protein coding sequences in the matrix domain

We have constructed human immunodeficiency virus (HIV) gag mutants by increasing the matrix protein (MA) sequences via tandemly repeated duplication of the central 107-MA codons. Instead of a total of 132 amino acid residues for the wild-type MA, the resultant mutants designated as MA2, MA3, and MA4 contained a total of 242, 352, and 462 codons in the MA domains, respectively. Analysis indicated that the addition of 110 or 220 amino acid residues to the MA did not significantly affect the assembly, release, and processing of particles; however, particle production was markedly reduced when another copy of 110 residues was added to the MA. Subcellular fractionation analysis suggested that the MA tandem repeat mutations enhanced the Gag membrane affinity, in a manner which correlated with the copy number of MA sequences. The effects of enhanced membrane affinity were substantially reduced when sequences downstream of the capsid (CA) domain were deleted. Sucrose density gradient fractionation analysis showed that particles produced by the large insertion mutants possessed wild-type (wt) HIV particle density. Truncation of sequences downstream of the nucleocapsid (NC) domains of the mutants did not influence the budding of particles. In contrast, particle budding was severely impaired when sequences downstream of the CA domain were truncated. Particle densities for the large Gag proteins, which were truncated at the C-terminus of CA, were about 1.12-1.14 g/ml lower than that for wt. Our results suggest that the HIV MA domain could adopt insertions of large protein sequences, and strongly support the proposal that the NC and p2 domains play a crucial role in the process of correct Gag protein packing.

[3D solid model of mandible with dental arch via LOM method]

OBJECTIVE

Based on 3D reconstruction data from CT scanning, a solid model of mandible with dental arch is obtained via a rapid prototype machine using LOM method.

METHODS

3D reconstruction data is transferred to STL file using software of Delcam(UK),which will be fed to Magics RP software for detection and rebuilding. Reproduction of the papery model of mandible with dental arch is then performed with highly geometric similarity.

RESULTS

The RP model of mandible with dental arch is obtained.

CONCLUSION

Accuracy of the reproduction model meets the demands of students in prosthetic dentistry,which gives the possibility of computer aided design of prosthetic dentistry based on 3D solid model.

[3D geometric simulation of mandible with dental arch from CT data]

OBJECTIVE

A 3D geometric simulation of mandible with dental arch from CT has been obtained in this study.

METHODS

This process uses automatic system assisted with interactive action to get 2D contour data from CT images,then 3D wireframe model and solid model were obtained by using CAD/CAM software Pro-E(USA) and DELCAM(UK).

RESULTS

3D solid model of mandible with dental arch were presented which can be fully edited.

CONCLUSION

This model can be applied to further educational and clinical researches such as RP,biomechanics simulation in prosthetic dentistry.The processes of simulation has wide applications in clinical practice of dentistry and dental education.

Mycobacterial infection of the upper extremities

BACKGROUND AND PURPOSE

Mycobacterial infection of the upper extremities is extremely rare. To make an early accurate diagnosis is often difficult, and the treatment is, therefore, frequently delayed in clinical practice. This paper describes the diagnosis and treatment of mycoabacterial infection of the upper extremities in a series of patients treated at National Taiwan University Hospital.

METHODS

The medical records of 15 patients with mycobacterial infection of the upper extremities treated between 1985 and 1998 were retrospectively analyzed. The diagnosis of mycobacterial infection was established by positive culture results, the presence of acid-fast bacilli, or characteristic histopathologic findings.

RESULTS

Mycobacterial infection was suspected on initial examination in only two patients. The duration between the onset of symptoms and correct diagnosis averaged 37.5 months (range, 3 wk to 209 mo). The involved sites of mycobacterial infection included the wrist in nine patients, the elbow in two, the hand in two, the humerus in two, the forearm in one, and the shoulder in one. Three patients suffered from multifocal musculoskeletal mycobacterial infection. Microbiologic studies identified Mycobacterium tuberculosis in four patients and nontuberculous mycobacteria (NTM) in four. Characteristic histopathologic findings of mycobacterial infection including caseation, granulomatous inflammation, eosinophilic epithelioid cells, Langhan's giant cells, and lymphocytic aggregates were noted in all 15 patients. All patients received chemotherapy and 14 patients underwent surgical treatment. The mean duration of follow-up was 46 months (range, 15-97 months). Treatment failed in two of the patients with multifocal NTM infection and in one patient whose mycobacterial infection was identified by histopathology.

CONCLUSIONS

Mycobacterial infection should be included in the differential diagnosis of infection of the upper extremities. Treatment failures are more frequent in patients with multifocal NTM infection.

Analysis of a human immunodeficiency virus type 1 gag mutant with an engineered 110-amino-acid insertion in the matrix protein domain

A human immunodeficiency virus (HIV) matrix (MA) protein mutant was constructed by duplication of 107 codons of the HIV-1 MA domain. This MA protein duplication mutant (MAII) still could assemble and process particles, had a wild-type (wt) HIV particle density, and possessed reverse transcriptase activity of about 80% of the wild type virus level. The incorporation of HIV Env and viral RNA genome was not greatly affected. The MAII was noninfectious or poorly infectious, however, when pseudotyped with an amphotropic murine leukemia virus envelope protein or with the HIV envelope protein. Although the MAII mutant displayed an immunofluorescence staining pattern similar to that of the wild type virus, subcellular fractionation studies indicated that the membrane association of MAII Gag precursors was unstable under high-salt conditions. Electron microscopic studies showed that the mutant had a decreased density of particle cores compared with that of the wild type virus, suggesting an altered arrangement of the packed proteins. As this insertion in the MA gene caused no major effects on virus assembly implies that the HIV-1 gag has the potential to adapt large insertions of extra coding sequences without loss of the ability to direct particle assembly and release.

Impairment of pressure-natriuresis and renal autoregulation in ANG II-infused hypertensive rats

Chronic infusions of initially subpressor doses of angiotensin II (ANG II) lead to progressive hypertension over a 2-wk period and to augmented intrarenal ANG II levels. The present study was performed to investigate total renal blood flow (RBF) and medullary blood flow (MBF) autoregulatory behavior and pressure-natriuresis in ANG II-infused hypertensive rats and how these are modified by concomitant treatment with an ANG II AT(1) receptor antagonist. ANG II-infused rats (n = 27) were prepared by administration of ANG II at 60 ng/min via osmotic minipump for 13 days. Twelve of the ANG II-infused hypertensive rats were treated with losartan in the drinking water (30 mg. kg.(-1) day(-1)). Rats were anesthetized with pentobarbital sodium (50 mg/kg, ip) and prepared for renal function measurements. An aortic clamp was placed above the junction of the left renal artery to reduce renal arterial pressure. Autoregulatory responses for renal plasma flow, overall RBF, and glomerular filtration rate were impaired in ANG II-infused hypertensive rats; however, MBF autoregulation was not disrupted. Most strikingly, pressure-natriuresis was markedly suppressed in ANG II-infused hypertensive rats. Chronic treatment with losartan prevented the impairment of the pressure-natriuresis relationship caused by chronic ANG II infusion. These findings demonstrate that chronic ANG II infusion leads to marked impairment of sodium excretion and suppression of the pressure-natriuresis relationship, which may contribute to the progressive hypertension that occurs in this model. These renal effects are prevented by simultaneous treatment with an AT(1) receptor blocker.

Multimerization potential of the cytoplasmic domain of the human immunodeficiency virus type 1 transmembrane glycoprotein gp41

We previously demonstrated that an envelope mutant of human immunodeficiency virus type 1 lacking the entire cytoplasmic domain interferes in trans with the production of infectious virus by inclusion of the mutant envelope into the wild-type envelope complex. We also showed that the envelope incorporation into virions is not affected when the wild-type envelope is coexpressed with the mutant envelope. These results suggest that an oligomeric structure of the cytoplasmic domain is functionally required for viral infectivity. To understand whether the cytoplasmic domain of human immunodeficiency virus type 1 transmembrane protein gp41 has the potential to self-assemble as an oligomer, in the present study we fused the coding sequence of the entire cytoplasmic domain at 3' to the Escherichia coli malE gene, which encodes a monomeric maltose-binding protein. The expressed fusion protein was examined by chemical cross-linking, sucrose gradient centrifugation, and gel filtration. The results showed that the cytoplasmic domain of gp41 assembles into a high-ordered structural complex. The intersubunit interaction of the cytoplasmic domain was also confirmed by a mammalian two-hybrid system that detects protein-protein interactions in eucaryotic cells. A cytoplasmic domain fragment expressed in eucaryotic cells was pulled down by glutathione-Sepharose 4B beads via its association with another cytoplasmic domain fragment fused to the C terminus of the glutathione S-transferase moiety. We also found that sequences encompassing the lentiviral lytic peptide-1 and lentiviral lytic peptide-2, which are located within residues 828-856 and 770-795, respectively, play a critical role in cytoplasmic domain self-assembly. Taken together, the results from the present study indicate that the cytoplasmic domain of gp41 by itself is sufficient to assemble into a multimeric structure. This finding supports the hypothesis that a multimeric form of the gp41 cytoplasmic domain plays a crucial role in virus infectivity.

Assembly and processing of human immunodeficiency virus Gag mutants containing a partial replacement of the matrix domain by the viral protease domain

We constructed human immunodeficiency virus (HIV) mutants by replacing the matrix domain with sequences encoding the viral protease or p6* and protease. The chimeras retaining matrix myristylation and processing signals underwent efficient autoprocessing with severely defective particle budding. The budding defects of the chimeras were rescued by suppressing the chimera protease activity either through addition of an HIV protease inhibitor or through inactivating the chimera protease via a substitution mutation of the catalytic aspartic acid residue. This resulted in the release of chimeric virus-like particles with the density of a wild-type retrovirus particle. In addition, the assembly-competent but processing-defective chimeras produced proteolytically processed particles with significant reverse transcriptase activity when a downstream native pol gene was present. These results suggest that HIV has the potential to adapt heterologous sequences in place of the matrix sequence without major effects on virus-like particle budding. In addition, the positions of the protease and substrate accessibility may contribute significantly toward avoiding a premature Gag or Gag-Pol process, which leads to severe defects in both particle budding and incorporation.

Heritabilities and genetic correlations of body weights and feather length in growing Muscovy selected in Taiwan

1. Heritabilities and genetic correlations in the base population of a closed strain of Muscovy duck, moderately selected for body weight at 10 weeks of age, have been estimated from the data of 9 successive generations for the following traits: male and female body weight at 10 and 18 weeks of age (BW10m, BW18m, BW10f, BW18f) and length of the 8th primary feather at 10 weeks of age (F110m, F110f). 2. Multivariate REML with an animal model was used, pooling data from the 9 generations (3283 and 3289 male and female offspring respectively). The same trait expressed in male and female was considered as 2 different traits. 3. The 8th primary feather was longer in females than in males by 6% to 22% at 10 weeks of age. Body weight was heavier in males than in females by 42% to 58% at 10 weeks of age and by 57% to 75% at 18 weeks of age. 3. The heritability estimates for body weight traits showed moderate values, being a little higher for females than for males at the same age, increasing with age from h2=0.24 at BW10m to h2=0.43 at BW18f. 4. The heritability estimates for feather length showed that a greater response would be obtained in selection for male feather length (h2=0.37) than for female length (h2=0.14). Both have high genetic correlations with body weight so they could be indirectly improved. 5. Heritabilities of the difference in body weights between males and females at 10 weeks (h2=0.07) and 18 weeks of age (h2=0.10) were small, as well as for feather length (h2=0.10). It would probably be difficult to modify sexual dimorphism in body weight through selection. 6. Genetic correlations between BW10m, BW18m and BW10f, BW18f were respectively r(g)=0.77 and r(g)=0.80. They were larger for body weight at the same ages between males and females, r(g)=0.90 (r(g)=0.88 between F110m and F110f). Body weight in males and females at the same age should be better considered as 2 different traits in a selection programme. 7. The cumulated predicted genetic gains expressed per unity of the genetic standard deviation (sigma(g)) over the 8 generations of selection were 1.3 sigma(g) and 1.4 sigma(g) respectively for the BW10m and BW10f. The predicted correlated responses were 1.2 sigma(g) for body weights at 18 weeks of age, 0.9 sigma(g) and 0.7 sigma(g) for F110f and F110m respectively.

Sequence requirements for incorporation of human immunodeficiency virus gag-beta-galactosidase fusion proteins into virus-like particles

The incorporation of human immunodeficiency virus type 1 (HIV-1) Gag-beta-galactosidase (Gag-beta-gal; GBG) fusion proteins into HIV virus-like particles in the presence of HIV Gag proteins was studied. HIV Gag-beta-gal fusion constructs were cotransfected individually into COS7 cells with or without an HIV Gag protein expression plasmid. Release of HIV GBG fusion proteins from the cells were measured by assay of the medium versus intracellular beta-gal activities. Analysis indicates that fusion proteins (constructs HIVGBG, GBG 1919 and 1877) retaining the C-terminal portion of the CA and the adjacent NC domains were efficiently assembled into virus-like particles. Fusion proteins with deleted sequences covering the N-terminal portions of the gag sequences (GBG 831, 1147, 1419, 1447, 1511, 1552, 1600, 1630, 1684, 1715, and 1752) were impaired in entry into virus-like particles. The presence of CA major homology region (MHR) in the fusion proteins had no significant effects on inducing fusion protein incorporation when the C-terminal CA sequences in the fusion proteins were truncated (GBG 1841 and 1801). Subcellular fractionation studies indicated that most fusion proteins including the nonmyristylated one were enriched in the crude membrane fraction. Exceptions to this rule were fusion proteins with intact MHR but truncated C-terminal CA sequences, which possessed low levels of membrane association. However, assembly of fusion proteins into HIV Gag particles did not correlate with their subcellular fractionation or immunofluorescence localization patterns. Overall, the studies suggest that the very C-terminal CA and adjacent NC sequences are the primary determinants for incorporation of HIV Gag-beta-gal fusion proteins into virus particles.

Diagnosing and treating asymptomatic tuberculosis infection

OBJECTIVE

To summarize relevant parts of the guidelines recommended by the Canadian and American Thoracic Societies for diagnosis and management of asymptomatic tuberculosis (TB) infection.

QUALITY OF EVIDENCE

The latest guidelines published by the Canadian and American Thoracic Societies were reviewed. Unfortunately, neither of these guidelines state explicitly how recommendations were derived. The references accompanying each set of guidelines, however, suggest that they were developed by extensive literature review of the subject and consensus among expert panels.

MAIN MESSAGE

Only higher-risk patients should receive a TB screening test (Mantoux test) to minimize the possibility of false-positive test results. The cutoff points for positive tests vary to reflect the pretest likelihood of TB infection. An induration 5 mm or greater is considered positive in patients at highest risk of TB infection, that is, HIV-infected patients, close contacts of active TB cases, and patients with chest x-ray abnormalities suggestive of previous untreated TB. All other patients are considered positive if they have induration greater than 10 mm according to the Canadian guideline. A 15-mm cutoff point, however, is used for patients without risk factors in the American guideline. All patients with positive Mantoux test results should be considered infected with TB. Infected patients should be offered 6 to 12 months of isoniazid prophylaxis if they have HIV infection, if they have medical conditions that increase the risk of TB activation, or if they are younger than 35 years.

CONCLUSIONS

Prophylactic treatment of infected individuals effectively prevents the spread of TB infection. Family physicians, who most often see patients in the asymptomatic stage of TB infection, are uniquely situated to prevent secondary cases of TB by offering appropriate patients prophylactic treatment. Patients should be counseled about the risk and benefit of prophylactic treatment so they give informed consent for it.

Differential effects of ganodermic acid S on the thromboxane A2-signaling pathways in human platelets

Ganodermic acid S (GAS) [lanosta-7,9(11),24-triene-3beta,15alpha-diacetoxy-26-oic acid], isolated from the Chinese medicinal fungus Ganoderma lucidum (Fr.) Karst (Polyporaceae), exerted a concentration-dependent inhibition on the response of human gel-filtered platelets (GFP) to U46619 (9,11-dideoxy-9alpha,11alpha-methanoepoxyprostaglandin F2alpha), a thromboxane (TX) A2 mimetic. GAS at 2 microM inhibited 50% of cell aggregation. GAS at 7.5 microM inhibited 80% of Ca2+ mobilization, 40% of phosphorylation of myosin light chain and pleckstrin, 80% of alpha-granule secretion, and over 95% of aggregation. GAS also strongly inhibited U46619-induced diacylglycerol formation, arachidonic acid release, and TXB2 formation. An immunoblotting study of protein-tyrosine phosphorylation showed that GAS inhibited the formation of phosphotyrosine proteins at the steps involving the engagement of integrin alphaIIbbeta3 and aggregation. However, GAS did not inhibit U46619-induced platelet shape change or the inhibitory effect of U46619 on the prostaglandin E1-evoked cyclic AMP level in GFP. It is concluded that GAS inhibits platelet response to TXA2 on the receptor-Gq-phospholipase Cbeta1 pathway, but not on the receptor-G1 pathway.

Cation permeability and cation-anion interactions in a mutant GABA-gated chloride channel from Drosophila

To investigate the structural basis of anion selectivity of Drosophila GABA-gated Cl(-) channels, the permeation properties of wild-type and mutant channels were studied in Xenopus oocytes. This work focused on asparagine 319, which by homology is one amino acid away from a putative extracellular ring of charge that regulates cation permeation in nicotinic receptors. Mutation of this residue to aspartate reduced channel conductance, and mutation to lysine or arginine increased channel conductance. These results are consistent with an electrostatic interaction between this site and permeating anions. The lysine mutant, but not the arginine mutant, formed a channel that is permeable to cations, and this cannot be explained in terms of electrostatics. The lysine mutant had a 25-mV reversal potential in solutions with symmetrical Cl(-) and asymmetrical cations. The permeability ratio of K(+) to Cl(-) was determined as 0. 33 from reversal potential measurements in KCl gradients. Experiments with large organic cations and anions showed that cation permeation can only be seen in the presence of Cl(-), but Cl(-) permeation can be seen in the absence of permeant cations. Measurements of permeability ratios of organic anions indicated that the lysine mutant has an increased pore size. The cation permeability of the lysine-containing mutant channel cannot be accounted for by a simple electrostatic interaction with permeating ions. It is likely that lysine substitution causes a structural change that extends beyond this one residue to influence the positions of other channel-forming residues. Thus protein conformation plays an important role in enabling ion channels to distinguish between anions and cations.

[Effect of the abutments with reduced periodontal support on stress distribution of support tissue]

OBJECTIVE:This study applied finite element analysis (FEA) compared stress distribution characteristics of mandible,bilateral,SJ-1 bolt(extracoronal) distal extension attachment prostheses when the abutments were subject to eight different loss of periodontal support.METHODS:Finite element analysis.RESULTS:It was shown that periodontal support loss results in increased stress of the terminal abutment tooth without sudden changes.CONCLUSION:Compared favorable stress distribution result from splinted compromised abutment,and the first premolar periodontal support loss less than that of the second premolar and this loss below 30%.

[Effect of the number of splinted abutments on stress distribution of support tissue]

OBJECTIVE:This study applied an SJ-1 bolt attachment partial denture to restorate distal extension edentulous areas.Finite element analysis (FEA) was used to monitor induced around abutment supporting tissues under the different number of splinted abutments.METHODS:Finite element analysis. RESULTS:The result demonstrate that the reduction of the number of splinted unit from three to two resulted in an insignificant increase of stress records,whereas reduction of the number from two to one resulted in a significant increase of stress nine times greater than the three unit splint values.CONCLUSION:Hence,at least two teeth on each side should be splinted when SJ 1 bolt(extracoronal) distal extension attachment prostheses are used.