Combining a Frailty Index Based on Laboratory Data and Pneumonia Severity Assessments to Predict In-Hospital Outcomes in Older Adults with Community-Acquired Pneumonia

OBJECTIVES

Due to the increased morbidity, mortality, and cost of community-acquired pneumonia (CAP) in older people, strategies directed at improving disease evaluation and prevention are imperative. We independently compared the 30-day in-hospital mortality prediction ability of a frailty index based on laboratory data (FI-Lab) with that of the CURB-65 and the Pneumonia Severity Index (PSI) and then proposed combining them to further improve prediction efficiency.

DESIGN

Retrospective cohort study.

SETTING AND PARTICIPANTS

Patients aged ≥ 65 years (n = 2039) with CAP who were admitted to Jiangsu Provincial People's Hospital of Nanjing Medical University and Jiangsu Provincial Hospital of Chinese Medicine from January 2019 to June 2022.

MEASURES

The 29-item FI-Lab, PSI and, CURB-65 were administered at admission. We defined frailty by the cut-off value of the FI-Lab score (> 0.43). Multivariable logistic regression analysis, together with the calculation of the area under the receiver operating characteristic curve (ROC-AUC), was conducted to identify stratified risks and relationships between the three indices and 30-day mortality. Participants were divided into the following three groups based on age: 65-74 years, 75-84 years, and ≥ 85 years. Hazard ratios (HRs) and 95% confidence intervals (CIs) for mortality due to frailty were calculated.

RESULTS

A total of 495 participants ranging from 65 to 100 years of age were ultimately included and divided into age groups (65-74 years, n = 190, 38.4%; 75-84 years, n = 183, 37.0%; ≥ 85 years, n = 122, 24.6%). A total of 142 (28.7%) of the 495 patients were defined as having frailty. All three scores tested in this study were significantly associated with 30-day mortality in the total sample. The ORs were as follows: 1.06 (95% CI: 1.03-1.09, P < 0.001) and 2.33 (95% CI: 1.26-4.31, P = 0.007) for the FI-Lab when the score was treated as a continuous and categorical variable, respectively; 1.04 (95% CI: 1.02-1.05, P < 0.001) for the PSI; and 3.70 (95% CI: 2.48-5.50, P < 0.001) for the CURB-65. In the total sample, the ROC-AUCs were 0.783 (95% CI: 0.744-0.819) for the FI-Lab, 0.812 (95% CI: 0.775-0.845) for the PSI, and 0.799 (95% CI: 0.761-0.834) for the CURB-65 (P < 0.001). The ROC-AUC slightly improved when the FI-Lab was added to the PSI (AUC 0.850, 95% CI: 0.809-0.892, P = 0.031) and to the CURB-65 (AUC 0.839, 95% CI: 0.794-0.885, P = 0.002). Older patients with frailty showed a higher risk of in-hospital mortality, with an HR of 2.25 (95% CI: 1.14-3.58, P < 0.001).

CONCLUSION AND IMPLICATIONS

The FI-Lab seems to generate simple and readily available data, suggesting that it could be a useful complement to the CURB-65 and the PSI as effective predictors of 30-day mortality due to CAP in older populations.

[Cohort study of efficacy and safety of polatuzumab vedotin combined with immunochemotherapy in patients with relapse/refractory diffuse large B cell lymphoma]

Objective: To investigate the efficacy and tolerability of Polatuzumab vedotin+rituximab±bendamustine (Pola-(B)R) in relapse/refractory diffuse large B cell lymphoma (R/R DLBCL) patients. Methods: The clinical data of 21 patients enrolled in Chinese Pola compassionate use program (CUP) in 4 centers from November 2019 to August 2020 were collected. There were 15 males and 6 females, and the median age was 56 years (ranged 25-76 years). Of the patients, 10 cases received Pola-BR regimen and the other 11 received Pola-R. Their clinical features, regimens, efficacy, and adverse events (AEs) were retrospectively analyzed. Results: Twenty-one patients with at least one efficacy evaluation were included. At data analysis cut-off point (12 Aug. 2020), the best overall response (BOR) rate was 81.0% (17/21) and the complete response (CR) rate was 19.0% (4/21). Kaplan-Meier survival estimation was performed, at a median follow-up of 54 days, three patients (14.3%) had disease progressed, and 18 patients (85.7%) were censored; the median progression-free survival (mPFS) was estimated to be 148 days. The incidence of adverse effects (AEs) of any grade was higher in Pola-BR group than Pola-R group (80.0% vs 63.6%). However, the incidence of grade 3-4 AEs were close in the two groups (30.0% vs 29.3%). The most common hematological toxicities were thrombocytopenia (28.6%, 6/21), neutropenia (28.6%, 6/21) and anemia (14.3%, 3/21), respectively. One patient with pneumonia and 1 patient with hemophagocytic syndrome recovered after symptomatic treatment. No peripheral neuropathy of grade≥2 was observed. Conclusions: The preliminary data suggested that, for heavily treated Chinese R/R DLBCL, the Pola-(B)R regimen still achieves promising efficacy and tolerable safety.

[Effect of bone marrow mesenchymal stem cells on paraquat-induced pulmonary fibrosis in rats]

Objective: To study the effect of the injected bone marrow mesenchymal stem cells (BMSC) on rats with pulmonary fibrosis induced by paraquat (PQ) during different poisoning periods and explore the potential mechanism. Methods: From October to December 2018, BMSCs of SPF SD rats were isolated and purified by whole-bone marrow adherent culture method and cultured to the Third Generation (P3) . The surface antigens CD29, CD90, CD45 and CD34 of P3 BMSC were detected by Flow cytometry, the formation of alkaline phosphatase (ALP) , calcium nodules and fat droplets were observed by ALP, Alizarin Red staining and oil red O staining. At the same time, 36 SPF male rats were randomly divided into 6 groups: NC Group (Blank Control Group, injected with the same amount of saline) and PQ group (PQ model group, injected with 20% PQ solution 18 mg/kg intraperitoneally) , bMSC-A group, BMSC-B group, BMSC-C group and BMSC-D group were injected with BMSC suspension 1×10(6) cells/mice at 3 h、3 d、7 d and 14 d after PQ poisoning. After 28 days, the rats were killed, the lung organ coefficients were calculated, the hydroxyproline (HYP) content in lung tissue was calculated by alkaline hydrolysis, and the lung injury and fibrosis were observed by HE and Masson staining, serum TGF-1、TNF-α、MMP-9 and TIMP-1 were detected by Elisa. Results: High Purity BMSCs were successfully isolated and obtained. The P3 BMSC generation was positive expression of CD29、CD90、and negative expression of CD34、CD45, and had the potential of osteogenic and adipogenic differentiation. The results of HE staining and Masson staining showed that the alveolar structure in NC group was intact and homogeneous, in PQ group, the alveolar structure was severely damaged and a lot of collagen fibers and fibroblasts were deposited, and the degrees of lung injury in each BMSC intervention group were obviously less than in PQ group, in BMSC-A group and BMSC-B group, the degrees of reduction were obvious. Compared with NC group, the Lung organ coefficient, HYP content in lung tissue and TGF-β1, TIMP-1 levels in serum were significantly higher in PQ group (P<0.05) , while TNF-α and MMP-9 had no significant difference (P>0.05) . Compared with PQ group, the lung organ Coefficients, HYP, TGF-1 and TIMP-β1 in BMSC-A and BMSC-B groups were lower than those in PQ group (P<0.05) . The Lung organ coefficients, TGF-β1 and TIMP-1 in BMSC-C and BMSC-D groups were lower than those in PQ group, there was no significant difference (P>0.05) . Conclusion: Early BMSC injecting can alleviate pulmonary fibrosis induced by PQ. The mechanism may be that BMSC can reduce pulmonary fibrosis through reducing the level of TGF-β1 and regulating the balance of TIMP-1/MMP-9, threrby reducing inflammatory damage and increasing the degradation of extracellular matrix (ECM) .

[Current status and prospects of population exposure assessment of nanomaterials consumer products]

With the wide application of nanomaterials in consumer products in the market, it is necessary to understand the existence and release of nanomaterials in consumer products, as well as the current situation of exposure assessment of consumers. China has been a large industrial producer with a huge consumer market, but the supervision of consumer goods with nanomaterials is almost blank. This article summarized and classified the existing consumer products of nanomaterials in the international market, and discussed the release of key nanomaterials in consumer products and the exposure assessment methods of consumers, in order to provide a scientific basis for the establishment of a regulatory system for consumer products of nanomaterials in China in the future.

[Experts consensus for the diagnosis, treatment, and prevention of Coronavirus disease 2019 in the elderly]

Coronavirus disease 2019 (COVID-19) can cause great damage to the elderly patients and lead to high mortality. The clinical presentations and auxiliary examinations of the elderly patients with COVID-19 are atypical, due to the physiological ageing deterioration and basal pathological state. The treatment strategy for the elderly patients has its own characteristics and treatment protocol should be considered accordingly. To improve the diagnosis, treatment, and prevention of COVID-19 in the elderly, the Expert Committee of Geriatric Respiratory and Critical Care Medicine, China Society of Geriatrics established the "Expert consensus for the diagnosis, treatment, and prevention of Coronavirus disease 2019 in the elderly" . We focused on the clinical characteristics and key points for better treatment and prevention of COVID-19 in the elderly. (1) For diagnosis, atypical clinical presentation of COVID-19 in the elderly should be emphasized, which may be complicated by underlying disease. (2) For treatment, strategy of multiple disciplinary team (mainly the respiratory and critical care medicine) should be adopted and multiple systemic functions should be considered. (3) For prevention, health care model about integrated management of acute and chronic diseases, in and out of hospital should be applied.

Modeling forest management effects on water and sediment yield from nested, paired watersheds in the interior Pacific Northwest, USA using WEPP

The Water Erosion Prediction Project (WEPP) model was applied to seven paired, nested watersheds within the Mica Creek Experimental Watershed located in northern Idaho, USA. The goal was to evaluate the ability of WEPP to simulate the direct and cumulative effects of clear-cutting and partial-cutting (50% canopy removal) on water and sediment yield. WEPP was modified to better represent changes in the Leaf Area Index during post-harvest forest vegetative recovery. Good agreement between simulated and observed streamflow was achieved with minimal to no calibration over a 16-year (1992-2007) period. For the seven watersheds and the entire study period, the overall Nash-Sutcliffe Efficiency (NSE), Kling-Gupta efficiency (KGE), and deviation of runoff volume (D_V) between observed and simulated daily streamflow ranged 0.58-0.71, 0.67-0.81, and -4% to 9%, respectively. Good agreement between predicted and observed suspended sediment yield was achieved through the calibration of a single channel critical shear stress parameter. For sediment yield, NSE, KGE, and D_V ranged 0.62-0.97, 0.43-0.97, and -2% to 2%, respectively, for the calibration period, and 0.61-0.93, 0.42-0.95, and -24% to 13%, respectively, for the period of model performance assessment. Regression analysis of observed- and WEPP-simulated increase in water and sediment yield following clear-cut treatment was similar; however, the WEPP-simulated increase was lower compared to observations particularly from the partial-cut watershed. The variability in the critical shear parameter for different stream channels in the study watersheds was directly related to the observed mean particle size on the stream bed and suggests that applications of the WEPP model in ungauged basins could potentially set the critical shear parameter based on particle size. Overall, the simulated results demonstrate the potential of WEPP as a modeling tool for forestland watershed management, particularly for estimating the effects of forest harvest on hydrograph fluctuations and consequently, stream sediment transport.

[Analysis on reproductive health service, demographics and characteristics of internal migrant population in three municipalities of China]

Objective: To investigate the utilization of reproductive health services and relating factors among internal migrant population in Beijing, Shanghai and Chongqing. Methods: A multi-stage cluster sampling method was adopted in this cross-sectional study, conducted in Beijing, Shanghai and Chongqing from August 2014 to August 2015. Standard methods on statistics and nonlinear canonical correlation were applied. Results: Out of the 6 545 internal migrant persons, 41.76% ever used the reproductive health services in the past year. Results from the nonlinear canonical correlation analysis revealed that the utilization of reproductive health services was correlated with the demographic features (=0.28, P<0.000 1) and characteristics of the population mobility (=0.21, P<0.000 1), respectively. For the above said demographic features, canonical variable L(1) which represented the demographic features was mainly determined by area, occupation and education attainment. Canonical variable M(1) that reflected the utilization of reproductive health services, was mainly determined by factors as free contraceptives, education on contraception/reproductive health, and pregnancy diagnosis/antenatal care. As for the characteristics of the population mobility, canonical variable U(1), which represented population mobility characteristics, was mainly determined by factors as purpose of migration, current pattern of residence and the length of annual stay in the area. Again, the canonical variable V(1), reflecting the use of reproductive health services was mainly determined by factors as free contraceptives, check-up on reproductive tract infection, education on contraception/reproductive health, and pregnancy diagnosis/antenatal care. Conclusions: The utilization of reproductive health services was low among the internal migrant population under study. Responsible departments for health and family planning in those cities should make internal migrants attach importance to reproductive health.

Trichostatin A inhibits proliferation of triple negative breast cancer cells by inducing cell cycle arrest and apoptosis

Triple negative breast cancer (TNBC) is the most aggressive subtype of breast cancer with poor outcome. Because of lacking therapeutic targets, chemotherapy is the main treatment option for patients with TNBC. Overexpression of HDACs correlates with tumorigenesis, highlighting the potential of HDACs as therapeutic targets for TNBC. Here we demonstrate that trichostatin A (TSA, a HDAC inhibitor) selectively inhibits the proliferation of TNBC cell lines HCC1806 and HCC38 rather than a normal breast cell line MCF10A. The inhibition of TNBC by TSA is via its roles in inducing cell cycle arrest and apoptosis. TSA treatment leads to decreased expression of CYCLIN D1, CDK4, CDK6 and BCL-XL, but increased P21 expression. Moreover, combination of TSA with doxorubicin has synergistic effects on inhibiting proliferation of HCC1806 and HCC38 cells. Our studies identified a promising epigenetic-based therapeutic strategy that may be implemented in the therapy of fatal human breast cancer.

[In vitro early detection of amyloid plaques in Alzheimer's disease by Pittsburgh compound B-modified magnetic nanoparticles]

Objective: To construct magnetic nanoparticles targeting β-amyloid (Aβ) plaques, the pathological biomarker of Alzheimer's disease (AD) and to study their binding capability in vitro. Methods: Superparamagnetic nanoparticles Mn(0.6)Zn(0.4)Fe(2)O(4) (MZF) were coated with amphiphilic star-block copolymeric micelles and modified with Aβ-specific probe Pittsburgh compound B (PiB) to construct a novel magnetic nanoparticle MZF-PiB, which specifically targeted amyloid plaques. Transmission electron microscope was used to study the morphological features of MZF-PiB. Superparamagnetism of MZF-PiB was assessed by its r(2) relaxation rate by using 3.0 T MRI scanner. Cytotoxic test was applied to determine biosafety of MZF-PiB nanoparticles in differentiated human neuroblastoma cells (SH-SY5Y) and Madin-Darby canine kidney (MDCK). In vitro binding tests were conducted via immunohistochemistry on 6-month old AD mice brain sections. Differences of cell viability between groups were compared with one-way analysis of variance. Results: MZF-PiB nanoparticles were successfully constructed. Transmission electron microscope images showed that the nanoparticles were about 100 nm in size. The r(2) relaxation rate was 163.11 mMS(-1). No differences were found in cell viability of SH-SY5Y and MDCK incubated with MZF-PiB suspension for 24 h or 48 h when compared with those of untreated cells (F=2.336, 2.539, 0.293, 1.493, all P>0.05). In vitro binding tests indicated that the MZF-PiB were specifically bound to amyloid plaques. The smallest size of detected plaques was 27 μm. Conclusion: PiB-modified nanoparticles targeting Aβ are biologically safe and highly superparamagnetic, possessing the capability to detect amyloid plaques early in vitro and the potential for early diagnosis of AD.

[Accuracy analysis of alveolar dehiscence and fenestration of maxillary anterior teeth of Angle class III by cone-beam CT]

OBJECTIVE

To evaluate the accuracy and reliability of detecting alveolar bone dehiscence and fenestration of maxillary anterior teeth of Angle class III by cone-beam computed tomography (CBCT).

METHODS

Eighteen Angle class III patients with 108 maxillary anterior teeth were included (3 males and 15 females) who accepted modified corticotomy in orthodontic therapy. The mean age was 23.6 years (18-30 years). The clinical detection of dehiscence and fenestration was done when modified corticotomy was performed by the same periodontist. The CBCT examination was conducted pre-operation and the detection of dehiscence and fenestration by CBCT was done by two periodontists. The data in modified corticotomy were used as the golden standard to calculate the parameters, such as sensitivity, specificity, positive and negative predictive values, Youden index (YI), positive and negative likelihood ratio. Kappa statistic was used to analyze the agreement between the clinical detection and the CBCT detection.

RESULTS

The incidence of dehiscence and fenestration was about 10.19% and 13.89% respectively, which mainly occurred on lateral incisors and canines. The median values of length and width of dehiscence were about 5 mm and 4 mm, and the median values of length and width of fenestration were 3 mm and 2 mm, respectively. Most fenestrations were detected on the middle third to the apical third of the root. For dehiscence, the agreement between clinical detection and CBCT detection was statistically significant (P<0.05). For fenestration, the agreement between clinical detection and CBCT detection was statistically significant (P<0.05). The values of sensitivity and specificity for detecting dehiscence were more than 0.7. The values of positive and negative predictive values for detecting dehiscence were 0.44 and 0.97. The values of sensitivity and specificity for detecting fenestration were 0.93 and 0.52. The values of positive and negative predictive values for detecting fenestration were 0.24 and 0.98.

CONCLUSION

For dehiscence, the agreement between clinical detection and CBCT detection was good. For fenestration, the agreement between clinical detection and CBCT detection was general. Detection of dehiscence and fenestration of maxillary anterior teeth of Angle class III by CBCT had limited diagnostic value in clinical practice with overestimation of dehiscence and fenestration incidence.

[The effects of different tidal volume ventilation on right ventricular function in critical respiratory failure patients]

Objective: To observe and explore the effects of different tidal volume (VT) ventilation on right ventricular (RV) function in patients with critical respiratory failure. Methods: Consecutive respiratory failure patients who were treated with invasive ventilator over 24 h in the Department of Critical Care Medicine at the Fourth Hospital of Hebei Medical University from June to December in 2015 were enrolled in this study.Clinical data including patients' vital signs, ventilator parameters and RV echocardiography were collected within 6 h (D0), day1(D1), day2 (D2) and day3 (D3) after ventilation started.According to the VT, patients with acute respiratory distress syndrome (ARDS) were assigned to low VT group [S6, ≤6 ml/kg predicted body weight (PBW)] and high VT group (L6, >6 ml/kg PBW), while non-ARDS patients were also assigned to low VT group (S8, ≤8 ml/kg PBW) and high VT group (L8, >8 ml/kg PBW). Results: A total of 84 patients were enrolled in this study.44.2% ARDS patients and 58.5% non-ARDS patients were in low VT groups.After ventilation, tricuspid annulus plane systolic excursion(TAPSE)decreased progressively in S6 [from 18.30(16.70, 20.70) mm to 17.55(15.70, 19.50) mm, P=0.001], L6 [from 19.50(17.00, 21.00) mm to 16.30(15.00, 18.00) mm P=0.001], S8[from 18.00(16.00, 21.00) mm to 16.50(15.50, 18.00) mm, P=0.001] and L8 [from 19.00(17.50, 21.50) mm to 16.35(15.15, 17.00) mm, P=0.001] groups.However, TAPSE decreased less in small VT groups (S6 and S8) than those of in large VT groups (S8 and L8) without significant differences.There were not statistical differences between different VT groups in terms of ventilation days, including right ventricle area/left ventricle area (RV(area)/LV(area)), TAPSE, peak mitral flow velocity of the early rapid filling wave (E), peak mitral flow velocity of the late rapid filling wave (A), early diastolic velocity of the tricuspid annulus (e'), pulmonary artery systolic pressure, inferior vena cava diameter (all P>0.05). Compared to L6 group, low VT (S6 group) resulted in decreased mortality at 28 days [1/19 vs 37.5%(9/24), P=0.014]. There were not statistical differences between different VT groups in terms of ventilation days, length of intensive care unit stay, length of hospital stay (all P>0.05). Logistic regression analysis showed that VT could be the independent factor of TAPSE (OR=1.104, 95%CI 0.100-1.003, P=0.049). Conclusions: Positive pressure mechanical ventilation resulted in RV systolic dysfunction .Lower VT may have the protective effect on RV function. Trial registration: Chinese Clinical Trial Registry, ChiCTR-POC-15007563.

[Follicular bronchiolitis: report of 3 cases and literature review]

Objective: To improve understanding of the characteristics of follicular bronchiolitis(FB). Methods: The clinical data of 3 patients with FB confirmed by thoracoscopic lung biopsy were retrospectively analyzed. A literature search was performed with "follicular bronchiolitis" as the key word in China Knowledge Resource Integrated Database, Wanfang and PubMed, Ovid Database. The time interval was from January 1947 to December 2015. Related articles of FB were retrieved and the clinical, radiographic characteristics and prognosis were analyzed. Results: Among the 3 patients, 1 was male and 2 were female, aging 32-55 years. Two patients were asymptomatic, and 1 patient presented with fever, cough and dyspnea. Two patients showed normal pulmonary ventilatory function with decreased diffusive function, and 1 patient showed normal pulmonary function. The predominant HRCT findings were bilateral multiple small nodules and cystic opacities, patchy ground-glass opacities, reticular opacities and traction bronchiectasis. The pathological examination by thoracoscopic biopsy revealed bronchiolar and peribronchiolar lymphoid follicles. All patients were treated with corticosteroids, with 2 patients receiving immunosuppressants. Follow-up HRCT after 1-2 months showed no improvement, and further follow-up HRCT after 2-4 years revealed no change in 2 patients while the other patient had increased pulmonary nodules and cystic opacities. Seventeen articles concerning FB with complete records were included in the literature review. A total of 64 patients were reported in these articles. The typical images were bilateral multiple small nodules and ground-glass opacities, reticular opacities, and cystic opacities. The majority of patients improved after treatment of corticosteroids and (or) immunosuppressants. But our 3 cases showed no improvement. Conclusions: FB is a rare small airway disease which has non-specific clinical manifestations and pulmonary function. The most common imaging findings are bilateral multiple small nodules, with cystic opacities, ground-glass opacities, and reticular opacities. Surgical thoracoscopic biopsy can get ideal specimen which is useful for diagnosis. The curative effects of corticosteroids or immunosuppressants on FB need to be further clinically investigated.

Increased expression of CXCR3 and its ligands in patients with vitiligo and CXCL10 as a potential clinical marker for vitiligo

BACKGROUND

Vitiligo is a skin disorder characterized by loss of melanocytes from the epidermis. A recent study reported that CXCL10 is critical for the progression and maintenance of depigmentation in a mouse model of vitiligo, but there is very limited clinical data regarding this issue and little is known about the dynamic changes or correlations with disease severity of these chemokines throughout the disease course.

OBJECTIVES

To present clinical data that supports and identifies the pathway of CXCR3 and its ligands in T-lymphocytic cell recruitment in vitiligo.

METHODS

Cytometric bead array, flow cytometry, quantitative real-time polymerase chain reaction and immunohistology were used to examine their systemic and local expression in 80 patients with vitiligo and 40 controls.

RESULTS

We showed that serum CXCL9 and CXCL10 were significantly elevated in patients with vitiligo and were higher in patients in progressive stages than in stable stages. The relative expression of CXCR3 mRNA in peripheral blood mononuclear cells was higher in vitiligo. There were higher percentages of both circulating CXCR3(+) CD4(+) and CXCR3(+) CD8(+) T cells in patients with progressive vitiligo compared with controls, while only the expression of CXCR3(+) CD8(+) T cells increased in patients with stable vitiligo. Histological findings also demonstrated an abundance of CXCR3(+) cells within vitiligo lesions. Furthermore, serum CXCL10 levels were associated with Vitiligo Area Scoring Index scores of patients with progressive vitiligo and were reduced after successful treatment.

CONCLUSIONS

The CXCL10/CXCR3 axis mediates T-cell recruitment into the skin in progressive vitiligo. Blocking this chemotactic mechanism may present a new form of therapy. Serum CXCL10 may be a novel biomarker in monitoring disease activity and guiding treatment of progressive vitiligo.

A recombinant plasmid of composite cysteine proteinase inhibitor/glyceraldehyde-3-phosphate dehydrogenase gene of periodic Brugia malayi functions on DNA immunity in the host

OBJECTIVES

Both cysteine proteinase inhibitors (CPIs) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) play important roles in the pathogenesis of parasites and their relationship with the hosts. We constructed a new eukaryotic recombinant expression plasmid pcDNA3.1(+)-BmCPI/BmGAPDH of periodic Brugia malayi for investigation of the DNA vaccine-elicited immune responses.

MATERIALS AND METHODS

We cloned a gene encoding the CPIs and GAPDH from periodic B. malayi into vector pcDNA3.1. The composited plasmid or the control was injected into the tibialis anterior muscle of the hind leg in BALB/c mice, respectively. The target genes were detected by reverse transcription-polymerase chain reaction in muscle tissues. The stimulation index (SI) of T-lymphocyte proliferation and the levels of interferon-gamma (INF-g) and interleukin-4 ( IL-4) in serum were detected by thiazolyl blue tetrazolium blue and enzyme-linked immunosorbent assays.

RESULTS

The pcDNA3.1(+)-BmCPI/BmGAPDH was amplified from muscle tissues of the mice after immunisation. The SI of the immunised group was significantly higher than that of the two control groups (P < 0.05). The levels of INF-g and IL-4 of pcDNA3.1(+)-BmCPI/BmGAPDH group were both higher than those of the two control groups (P < 0.05). The level of INF-g of pcDNA3.1(+)-BmCPI/BmGAPDH group was significantly higher than that of pcDNA3.1(+)-BmCPI/CpG group (P < 0.05).

CONCLUSIONS

We conclude that the recombinant plasmid pcDNA3.1(+)-BmCPI/BmGAPDH could elicit specific humoural and cellular immune responses in mice.

Suppression of lentivirus-mediated transgenic dendritic cells in graft-versus-host disease after allogeneic bone marrow transplantation in mice

We determined whether genetically engineered immature dendritic cells (imDCs) mediated by lentiviral vectors alleviate acute graft-versus-host disease (GVHD) after allogeneic bone marrow transplantation (allo-BMT) in mice. We introduced the mouse chemokine receptor 7 (Ccr7) gene into the bone marrow-derived imDCs of C57BL/6 mice to construct genetically engineered imDCs. A 1:1 mixture of bone marrow and spleen cells from the donors was injected into the recipients, which were divided into four groups: radiation, transplantation, empty vector, and transgenic imDC groups. Symptoms, clinical scores, GVHD pathological changes, and survival times and rates of recipients were recorded; secretion of IFN-γ and IL-4, and allogeneic chimerism rates were detected. The survival time of the transgenic imDC group (27.5 ± 7.55 days) was significantly longer than in the other three groups (P < 0.01). The GVHD score of the imDC group mice was significantly lower than in the transplantation and empty vector groups (P < 0.05), which meant that mice in the transgenic imDC group had the lightest pathology damage in the target organs. In the transplantation group, IFN-γ increased while IL-4 decreased. In contrast, IFN-γ decreased and IL-4 increased in both empty vector and trans-imDC groups, and the difference was significant in the latter (P < 0.01). Thirty days or more following transplantation, the allogeneic chimerism rate was still 95-100%, suggesting complete donor type implantation. Ccr7 transfection into imDCs suppressed occurrence and severity of acute GVHD after allo-BMT in mice; the mechanism might be associated with IFN-γ decrease and IL-4 increase.

Effects of zinc-methionine on growth performance, intestinal flora and immune function in pigeon squabs

1. Different concentrations of zinc-methionine (Zn-Met) were given to pigeon squabs, and the resulting effects on growth, immune functions and intestinal microflora were investigated from hatching to 28 d of age. A total of 180 artificially hatched pigeon squabs were randomly allotted to each of three treatments with three replicates of 20 squabs. The three treatments given were either one ml (2 mg/ml) Zn-Met, one ml (10 mg/ml) Zn-Met or one ml 0.9% NaCl solution. 2. The results showed that Zn-Met improved the growth performance of squabs. The average daily and average weekly weight gain was significantly greater in squabs treated with Zn-Met than in the control group. 3. The group given 2 and 10 mg supplemental Zn-Met had heavier thymus, spleen and bursa of Fabricius than the control group at d 28. 4. Maternal antibody titres against Newcastle disease haemagglutination inhibition and alpha-naphthyl acetate esterase were significantly higher in squabs treated with supplemental 2 and 10 mg Zn-Met compared to the control group at d 14 and d 28. 5. Additionally, the squabs given supplemental 2 mg Zn-Met exhibited significantly higher Bacillaceae, Lactobacillus, Enterococcus and Bifidobacterium populations at d 14 and d 28, but lower Escherichia coli populations at d 28 compared to the control group. On the contrary, Lactobacillus, Enterococcus and Bifidobacterium populations were significantly decreased with 10 mg Zn-Met at d 28. 6. This study indicates that supplementation with Zn-Met has a positive effect on growth performance, immune function and regulation of intestinal flora in pigeons. An inclusion level of 2 mg seems to be better than 10 mg Zn-Met per day per bird.

Riboflavin supplementation improves energy metabolism in mice exposed to acute hypoxia

This study investigated the effects of riboflavin on energy metabolism in hypoxic mice. Kunming mice were fed diets containing riboflavin at doses of 6, 12, 24 and 48 mg/kg, respectively for 2 weeks before exposure to a simulated altitude of 6000 m for 8 h. Changes of riboflavin status and energy metabolism were assessed biochemically. Simultaneously, a (1)H nuclear magnetic resonance (NMR) based metabolomic technique was used to track the changes of plasma metabolic profiling. It was found that the content of hepatic riboflavin was decreased and erythrocyte glutathione activation coefficient was elevated significantly under hypoxic condition. Meanwhile, increased plasma pyruvate, lactate, beta-hydroxybutyrate and urea, as well as decreased plasma carnitine were observed. Riboflavin supplementation improved riboflavin status remarkably in hypoxic mice and decreased plasma levels of pyruvate, free fatty acids and beta-hydroxybutyrate significantly. Plasma carnitine was increased in response to riboflavin supplementation. Results obtained from (1)H NMR analysis were basically in line with the data from biochemical assays and remarkable changes in plasma taurine, choline and some other metabolites were also indicated. It was concluded that riboflavin requirement was increased under acute hypoxic condition and riboflavin supplementation was effective in improving energy metabolism in hypoxic mice.

PKA phosphorylation reshapes the pharmacological kinetics of BmK AS, a unique site-4 sodium channel-specific modulator

Although modulation of the activity of voltage-gated sodium channels (VGSCs) by protein kinase A (PKA) phosphorylation has been investigated in multiple preparations, the pharmacological sensitivity of VGSCs to scorpion toxins after PKA phosphorylation has rarely been approached. In this study, the effects of BmK AS, a sodium channel-specific modulator from Chinese scorpion Buthus martensi Karsch, on the voltage-dependent activation and inactivation of Nav1.2 were examined before and after PKA activation. After PKA phosphorylation, the pattern of dose-dependent modulation of BmK AS, on both Nav1.2α and Nav1.2 (α + β1) was reshaped. Meanwhile, the shifts in voltage-dependency of activation and inactivation induced by BmK AS were attenuated. The results suggested that PKA might play a role in different patterns how β-like toxins such as BmK AS modulate gating properties and peak currents of VGSCs.

Microstructure change of ZnO nanowire induced by energetic x-ray radiation and its effect on the field emission properties

The changes in the microstructure of ZnO nanowire were studied after exposure to different radiation doses of energetic x-rays. Detailed structural, composition and optical analyses were carried out. It was found that the surface composition changed and defects were formed in the irradiated ZnO nanowires. The structural change of ZnO nanowires after thermal treatment was also studied and similar defects were observed. It is proposed that phonon-induced localized heating is the main reason for the observed changes in microstructure. Finally, the field emission properties of ZnO nanowires before and after x-ray radiation were studied. It was found that the increase of work function and change in morphology induced by the irradiation were the reasons for the observed change in field emission properties.

A wood-strand material for wind erosion control: effects on total sediment loss, PM10 vertical flux, and PM10 loss

Fugitive dust from eroding land poses risks to environmental quality and human health, and thus, is regulated nationally based on ambient air quality standards for particulate matter with mean aerodynamic diameter < or = 10 microm (PM10) established in the Clean Air Act. Agricultural straw has been widely used for rainfall-induced erosion control; however, its performance for wind erosion mitigation has been less studied, in part because straw is mobile at moderate wind velocities. A wood-based long-strand material has been developed for rainfall-induced erosion control and has shown operational promise for control of wind-induced erosion and dust emissions from disturbed sites. The purpose of this study was to evaluate the efficacy of both agricultural straw and wood-strand materials in controlling wind erosion and fugitive dust emissions under laboratory conditions. Wind tunnel tests were conducted to compare wood strands of several geometries to agricultural wheat straw and bare soil in terms of total sediment loss, PM10 vertical flux, and PM10 loss. Results indicate that the types of wood strands tested are stable at wind speeds of up to 18 m s(-1), while wheat straw is only stable at speeds of up to 6.5 m s(-1). Wood strands reduced total sediment loss and PM10 emissions by 90% as compared to bare soil across the range of wind speeds tested. Wheat straw did not reduce total sediment loss for the range of speeds tested, but did reduce PM10 emissions by 75% compared to a bare soil at wind speeds of up to 11 m s(-1).

Efficacy of nisin in treatment of clinical mastitis in lactating dairy cows

Nisin is an antimicrobial polypeptide produced by Lactococcus lactis and is believed nontoxic to humans. The objective of this study was to evaluate a nisin-based formulation for the treatment of bovine clinical mastitis in lactating dairy cattle. A total of 92 cows with 107 clinically mastitic quarters were randomly assigned to nisin- (48 cows with 51 quarters) and gentamicin (GM)-treated (44 cows with 56 quarters) groups. In the nisin-treated group, cows received an intramammary infusion of nisin at a dose of 2,500,000 IU; in the GM-treated group, intramammary infusion of GM was administered at a dose of 0.8 g. Results indicated that nisin offered a clinical cure rate similar to GM (90.2 vs. 91.1%) and no difference in bacteriological cure rate than GM-treated group (60.8 vs. 44.6%, respectively). Proportion of the quarters with milk somatic cell counts <500,000 cells/mL was not different in the nisin-treated group (50.0 and 47.8%) compared with the GM-treated group (33.3 and 37.3%) 1 and 2 wk after treatment. Of 17 Staphylococcus aureus isolates, 82.5% were resistant to penicillin, and 35.3% to GM, but none of them to nisin. Nisin therapy eliminated 54.5% (6 of 11) of S. aureus IMI, whereas GM eliminated 33.3% (2 of 6). Nisin in milk (4.5 +/- 0.8 IU/mL) was detected only at 12 h following intramammary infusion, which was much lower than the upper limit (500 mg/mL) allowed as preservative in milk by the China authority. Because of its efficacy in the treatment of bovine clinical mastitis, especially resistant Staph. aureus-caused IMI, as well as its safety in humans, nisin deserves further study to clarify its effects on mastitis caused by different mastitis pathogens on a larger scale.

Semen quality in a residential, geographic and age representative sample of healthy Chinese men

BACKGROUND

Population-based study of semen quality is rare in literature.

METHODS

Healthy men aged 20-60 years from six Chinese provinces were invited to participate in the study between December 2000 and November 2002. Posters were distributed in the participating counties to enroll 200 subjects from each province. Medians, percentiles, and proportions below lower threshold of the WHO criteria for semen parameters were calculated. Generalized linear models were used to examine the determinants of semen quality.

RESULTS

Semen samples from 1191 healthy Chinese men were collected and analysed. The medians (5th and 95th percentiles) were 2.3 ml (1.0-4.5) for semen volume, 65 x 10(6)/ml (20-150) for semen concentration, 154 x 10(6)/ejection (29-421) for sperm count, 19% (5-32) for rapid progressive motility, 46% (29-66) for progressive motility, 67% (47-81) for total motile spermatozoa, 70% (48-88) for sperm viability and 39% (23-76) for normal morphology. Many healthy Chinese men had semen parameter values below the lower threshold of the WHO criteria. Region, age, abstinence duration and season were important determinants of semen quality.

CONCLUSIONS

Chinese men have lower values of semen parameters according to WHO standard, and a lower threshold for normal semen parameters for Chinese men should be considered.

Roles of a fimbrin and an alpha-actinin-like protein in fission yeast cell polarization and cytokinesis

Eukaryotic cells contain many actin-interacting proteins, including the alpha-actinins and the fimbrins, both of which have actin cross-linking activity in vitro. We report here the identification and characterization of both an alpha-actinin-like protein (Ain1p) and a fimbrin (Fim1p) in the fission yeast Schizosaccharomyces pombe. Ain1p localizes to the actomyosin-containing medial ring in an F-actin-dependent manner, and the Ain1p ring contracts during cytokinesis. ain1 deletion cells have no obvious defects under normal growth conditions but display severe cytokinesis defects, associated with defects in medial-ring and septum formation, under certain stress conditions. Overexpression of Ain1p also causes cytokinesis defects, and the ain1 deletion shows synthetic effects with other mutations known to affect medial-ring positioning and/or organization. Fim1p localizes both to the cortical actin patches and to the medial ring in an F-actin-dependent manner, and several lines of evidence suggest that Fim1p is involved in polarization of the actin cytoskeleton. Although a fim1 deletion strain has no detectable defect in cytokinesis, overexpression of Fim1p causes a lethal cytokinesis defect associated with a failure to form the medial ring and concentrate actin patches at the cell middle. Moreover, an ain1 fim1 double mutant has a synthetical-lethal defect in medial-ring assembly and cell division. Thus, Ain1p and Fim1p appear to have an overlapping and essential function in fission yeast cytokinesis. In addition, protein-localization and mutant-phenotype data suggest that Fim1p, but not Ain1p, plays important roles in mating and in spore formation.

[Conical column end for wide bore packed capillary liquid chromatographic column]

Wide bore (> or = 0.5 mm i.d.) packed capillary liquid chromatographic columns with conical end were designed and evaluated. It was found that the column efficiency was 30%-50% higher than that of the packed capillary columns with conventional end connection at optimal flow rate, and was twice as much as that at reduced flow rate of 10-15. The chromatographic peak symmetry and the van Deemter curve of the novel shape column were also improved substantially. Fast analysis of PAHs is demonstrated.

Cytokinesis: an emerging unified theory for eukaryotes?

In animal and fungal cells, cytokinesis involves an actomyosin ring that forms and contracts at the division plane. Important new details have emerged concerning the composition, assembly, and dynamics of these contractile rings. In addition, recent advances suggest that targeted membrane addition is a central feature of cytokinesis in animal cells - as it is in fungi and plants - and the coordination of actomyosin ring function with targeted exocytosis at the cleavage plane is being explored. Important new information has also emerged about the spatial and temporal regulation of cytokinesis, especially in relation to the function of the spindle midzone in animal cells and the control of cytokinesis by GTPase systems.

Heterologous modules for efficient and versatile PCR-based gene targeting in Schizosaccharomyces pombe

We describe a straightforward PCR-based approach to the deletion, tagging, and overexpression of genes in their normal chromosomal locations in the fission yeast Schizosaccharomyces pombe. Using this approach and the S. pombe ura4+ gene as a marker, nine genes were deleted with efficiencies of homologous integration ranging from 6 to 63%. We also constructed a series of plasmids containing the kanMX6 module, which allows selection of G418-resistant cells and thus provides a new heterologous marker for use in S. pombe. The modular nature of these constructs allows a small number of PCR primers to be used for a wide variety of gene manipulations, including deletion, overexpression (using the regulatable nmt1 promoter), C- or N-terminal protein tagging (with HA, Myc, GST, or GFP), and partial C- or N-terminal deletions with or without tagging. Nine genes were manipulated using these kanMX6 constructs as templates for PCR. The PCR primers included 60 to 80 bp of flanking sequences homologous to target sequences in the genome. Transformants were screened for homologous integration by PCR. In most cases, the efficiency of homologous integration was > or = 50%, and the lowest efficiency encountered was 17%. The methodology and constructs described here should greatly facilitate analysis of gene function in S. pombe.

Phosphorescence and optically detected magnetic resonance characterization of the environments of tryptophan analogues in staphylococcal nuclease, its V66W mutant, and Delta 137-149 fragment

Phosphorescence and optically detected magnetic resonance (ODMR) measurements are reported on the triplet states of the tryptophan analogues, 7-azatryptophan (7AW), 5-hydroxytryptophan (5HW), and 4-, 5-, and 6-fluorotryptophan (4FW, 5FW, 6FW), when incorporated at position 140 of wild-type Staphylococcal nuclease (7AW-nuclease, etc. ), positions 66 and 140 of its V66W mutant (7AW-V66W, etc.), and the deletion fragment of the latter, Delta 137-149 (7AW-V66W', etc.). These measurements point to the retention of protein structure at position 140 in each of the wild-type nuclease analogues. Substitution of the analogue at both tryptophan sites of V66W leads to structured sites with differentiated triplet-state properties for all analogues except 7AW-V66W, whose structure is destabilized. 5HW-V66W' is the only fragment that apparently lacks structure at position 66. All other V66W' analogues exhibit a structured environment at position 66 (4FW-V66W' was not studied), but in each case this site can be differentiated readily from the corresponding site in intact V66W. 7AW-V66W' is resolved by ODMR into two discrete structures with slightly differing zero field splittings (ZFS). Interaction of the protein with 5HW at position 66 of 5HW-V66W induces a 2-fold increase in the ZFS E parameter, which is reduced to its normal value upon formation of the fragment, 5HW-V66W'. Analogous effects occur for 5FW, but on a smaller scale.

Study of complexes of a tryptophan-free mutant of E. coli trp aporepressor with tryptophan analogues using optically detected magnetic resonance (ODMR)

Phosphorescence and optically detected magnetic resonance (ODMR) spectra of tryptophan (W) and several of its analogues (4-, 5-, 6-methyltryptophan (MeW); 4-, 5-, 6-fluorotryptophan (FW); 5-bromotryptophan) are compared with those of complexes formed with the W-free trp aporepressor from Escherichia coli (W19,99F). W19,99F binds W and each analogue except 4-FW with an estimated KD < or = 30 microM; triplet state spectroscopic and kinetic effects that accompany binding at the corepressor site are reported. ODMR data for the MeW isomers are presented for the first time. No binding of 7-azaW is observed, in agreement with the low affinity found by previous workers.

Binding of the nucleocapsid protein of type 1 human immunodeficiency virus to nucleic acids studied using phosphorescence and optically detected magnetic resonance

The binding of p7 nucleocapsid protein of type 1 human immunodeficiency virus (HIV-1) to various oligonucleotides and polynucleotides has been investigated by phosphorescence and optically detected magnetic resonance (ODMR) spectroscopy. The intrinsic spectroscopic probe used in these studies is the photoexcited triplet state of Trp37, which is associated with the C-terminal zinc finger of p7 and is its only tryptophan residue. Complex formation produces a red-shift of the phosphorescence 0, 0-band (DeltaE0,0) of Trp37 as well as a reduction of the zero field splitting (zfs) D parameter. Increases of -DeltaE0,0 (A < C < U < G <I) rank with increasing binding affinity to nucleic acid homooligomers (A approximately C < U < G approximately I). It is proposed that the magnitude of the shift reflects the extent of aromatic stacking interactions. We propose also that -DeltaD increases not only with increased aromatic stacking but also with the extent of charge transfer (CT) character admixed into the triplet state. The quantity DeltaD/DeltaE0,0 correlates with the electron affinity of the bases (G < A < C < U approximately T), suggesting that this quantity reflects the extent of CT character admixed with the triplet state by the aromatic stacking interaction. Also affected by nucleic acid binding of p7 are the kinetic parameters of Trp37. We find a selective increase in the relative populating rate, and of the decay rate constant of the Tx sublevel. In binding of p7 to either d(IT)2 or d(IT)4, two distinct sets of triplet states of Trp37 are resolved, suggesting the existence of specific nucleic acid binding modes of these heterooligomers.

Growth-inhibitory and differentiation-inducing activity of dimethylformamide in cultured human malignant glioma cells

OBJECTIVE

To determine the growth-inhibitory and differentiation-inducing activity of dimethylformamide (DMF) on a human glioma cell line (SHG-44). DMF is a type of polar solvent and a potent differentiation-inducing agent in many kinds of human solid tumors, yet its effect on human glioma remains unclear.

METHODS

The effects of DMF on cell proliferation using 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, cell cycle distribution (with flow cytometry), colony-forming efficiency in double-layer soft agar, tumorigenicity in athymic nude mice, morphological changes, and glial fibrillary acidic protein expression were studied.

RESULTS

At dose ranges of 0.25, 0.5, 0.75, and 1.0%, DMF caused a dose-dependent proliferation inhibitory effect in monolayers and a marked dose-dependent suppression of colony-forming efficiency in double-layer soft agar with a complete loss of colony-forming ability in cells exposed to 0.75 and 1.0% DMF. Accumulation of cells in G0/G1 phases was observed in DMF-treated (0.5 and 1.0%) cells, also in a dose-dependent manner. SHG-44 cells exposed to DMF (0.5 and 1.0%) for 15 days changed morphologically from small spindle-shaped to large polygonal and flattened stellate cells with multiple slender processes. These cells were still tumorigenic in athymic nude mice, but the growth of xenografts was remarkably reduced, especially in the 1.0% DMF-treated group. The expression of glial fibrillary acidic protein was notably increased by DMF (0.5 and 1.0%). Washout experiments revealed that the effects of DMF on cell proliferation and cell cycle distribution were reversible.

CONCLUSION

Our results suggest that DMF drove the SHG-44 cells to a more mature phenotype with inhibited growth.

Fluorescence, phosphorescence, and optically detected magnetic resonance studies of the nucleic acid association of the nucleocapsid protein of the murine leukemia virus

Fluorescence, phosphorescence, and optical detection of triplet state magnetic resonance (ODMR) are employed to investigate the interaction of p10, the nucleocapsid protein of the Moloney murine leukemia virus, with nucleic acids. p10 is a 55-amino acid protein containing a single zinc finger motif, C26C29H34C39, that includes Y at position 28 and W at position 35. In addition, the interactions of a zinc finger peptide, p10-ZF, comprising residues 24-41 of p10, and a doubly mutated 24-41 peptide, p10-ZF' in which the positions of Y and W are interchanged, also are reported. The measurements focus on the direct involvement of the sole W residue in the nucleic acid interaction. Fluorescence quenching and salt-back titrations indicate complex formation of p10 with several octanucleotides--(dT)8, (dI)8, (dU)7dT, and (5-BrdU)7dT--and with the polynucleotides poly(dT) and poly(dI). Poly(dI) binds with the highest affinity. Apparent binding constants and salt-back midpoints are reported. Neither p10-ZF nor p10-ZF' exhibits significant fluorescence quenching by these DNA substrates. Binding of p10-ZF to fluorescent poly(ethenoadenylic acid) was detected with greatly reduced affinity relative to p10, but binding of p10-ZF' was undetectable. These results are in general agreement with phosphorescence and ODMR measurements monitoring W. Addition of poly(I) to p10 leads to a phosphorescence red shift, reduction in the zero-field splitting (ZFS) parameters D and E, and a significantly reduced phosphorescence lifetime, each consistent with aromatic stacking interactions between W and the nucleobases. These effects are smaller with p10-ZF and undetectable with p10-ZF'. Poly(U) produces no significant changes in the triplet state parameters of W; no stacking interactions are observed even for p10. (5-BrdU)7dT yields large phosphorescence red shifts in p10 and p10-ZF, and reductions of D, but no significant heavy atom effects. These effects probably are due to enhanced local polarizability caused by Br, but any stacking interactions in these complexes would exclude van der Waals contacts between W and the Br atoms.

Thermodynamics of the unfolding and spectroscopic properties of the V66W mutant of Staphylococcal nuclease and its 1-136 fragment

Spectroscopic studies have been performed to characterize the solution structure of the V66W mutant of Staphylococcal nuclease and the corresponding 1-136 fragment, referred to as V66W'. Whereas wild-type nuclease has a single tryptophan residue at position 140, the V66W mutant has a second tryptophan residue at position 66, which is the only such residue in V66W'. Steady-state and time-resolved fluorescence studies show Trp-66 in V66W' to have a blue emission, a relatively large fluorescence quantum yield, a long lifetime, a significant degree of protection from solute quenchers, and to depolarize with a relatively long rotational correlation time. These results characterize Trp-66 in V66W' as being a buried residue, which indicates that this fragment retains some global structure. Circular dichroism (CD) data are consistent with the fragment having lost most of the alpha-helical content of the wild type, while retaining beta-sheet structure. The CD spectrum in the aromatic region also suggests that Trp-66 in the fragment experiences an asymmetric environment, which is not identical to that in the full length mutant, V66W. In addition, optical detection of triplet state magnetic resonance (ODMR) spectroscopy can clearly resolve the tryptophan residues and demonstrates differences between the local environment of Trp-66 in V66W and in V66W', as well as small differences in the Trp-140 environment in wild type and in V66W. Guanidine-HCl induced and thermally induced unfolding studies were performed by simultaneously acquiring CD and fluorescence data as a function of the perturbation and then performing a global analysis of such multiple data sets in terms of two-state and three-state unfolding models. Whereas data for wild-type nuclease and the V66W' fragment are well characterized by a two-state unfolding model, data for the V66W mutant are better characterized by a three-state process. That is, both the denaturant- and temperature-induced unfolding of V66W involves the significant population of an equilibrium unfolding intermediate. Our global analyses yield thermodynamic parameters for the unfolding transitions, and we show that the data for V66W can be described by a constrained three-state model in which the transition of the intermediate to the fully unfolded state is fixed to have the same thermodynamic parameters that describe the unfolding of the V66W' fragment.

Effect of cations on the volume of the helix-coil transition of poly[d(A-T)]

The pressure dependence of the helix-coil transition temperature of poly[d(A-T)] has been measured in aqueous solutions of NaCl, KCl, and CsCl at concentrations between 0.02 and 1 M. In all cases the transition temperature increases with pressure. For solutions of NaCl, KCl and dilute CsCl the change in the transition temperature is linear with pressure up to 200 MPa. In more concentrated CsCl solutions the change in Tm with pressure was hyperbolic. The molar volume change of the transition (delta Vt) was calculated using the Clapeyron equation. At the lower salt concentrations, the derived values of delta Vt increase with the radius of the cation (Na+ < K+ < Cs+). At the higher salt concentrations delta Vt of poly[d(A-T)] in Na+ and K+ became equal; however, in CsCl solutions delta Vt was approximately twice as large as delta Vt in solutions containing the other two ions. In solutions of NaCl and KCl, delta Vt increased linearly with the logarithm of the salt concentration while in aqueous CsCl the concentration dependence of delta Vt was hyperbolic. The results are interpreted in terms of the role played by the radius of the cation in deciding the strength of the interactions formed with water.

Pressure dependence of the helix-coil transition temperature of poly[d(G-C)]

The pressure dependence of the helix-coil transition temperature (Tm) of poly[d(G-C)] was studied as a function of sodium ion concentration in phosphate buffer. The molar volume change of the transition (delta V) was calculated using the Clapeyron equation and calorimetrically determined enthalpies. The delta V of the transition increased from +4.80 (+/- 0.56) to +6.03 (+/- 0.76) mL mol-1 as the sodium ion concentration changed from 0.052 to 1.0M. The van't Hoff enthalpy of the transition calculated from the half-width of the differentiated transition displayed negligible pressure dependence; however, the value of this parameter decreased with increasing sodium ion concentration, indicating a decrease in the size of the cooperative unit. The volume change of the transition exhibits the largest magnitude of any double-stranded DNA polymer measured using this technique. For poly[d(G-C)] the magnitude of the change in delta V with sodium ion concentration (0.94 +/- 0.05 mL mol-1) is approximately one-half that observed for either poly[d(A-T)] or poly(dA).poly(dT). The delta V values are interpreted as arising from changes in the hydration of the polymer due to the release of counterions and changes in the stacking of the bases of the coil form. As a consequence of solvent electrostriction, the release of counterions makes a net negative contribution to the total delta V, implying that disruption of the stacking interactions contributes a positive volume change to the total delta V.(ABSTRACT TRUNCATED AT 250 WORDS)

Pressure dependence of the melting temperature of dA.dT polymers

The pressure dependence of the helix-to-coil transition temperature (Tm) of poly[d(A-T)], poly(dA).poly(dT), and poly(dA).poly(dT)2 was studied as a function of sodium chloride concentration. The molar volume change of the transition (delta V) was calculated using the Clapeyron equation and calorimetrically determined enthalpies. The delta V of the transition varied linearly with the logarithm of the salt concentration for both double-stranded polymers. The delta V of poly[d(A-T)] changed from +0.36 to +3.86 cm3 mol-1 as the sodium chloride concentration changed from 0.020 to 1.0 M. For poly(dA).poly-(dT), the delta V varied from +2.60 to +4.59 cm3 mol-1 over the range of 0.020-0.20 M NaCl. No pressure dependence of the van't Hoff enthalpy was observed for the double-helical form of either polymer. The delta V for denaturation of the triple-helical species poly(dA).poly(dT)2 was found to be +7.81 and +10.4 cm3 mol-1 at 1.0 and 3.0 M NaCl, respectively. The observed delta V values are interpreted in terms of changes in the hydration of the polymers arising from release of counterions and changes in the stacking of the bases upon denaturation. Counterion release is assumed to make a net negative contribution to the overall delta V, implying that disruption of the stacking interactions must make a positive volume change to the overall delta V. The difference in the delta V values for the two polymers remains constant as the salt concentration is changed, suggesting a difference in the partial molar volume of their single-stranded forms.(ABSTRACT TRUNCATED AT 250 WORDS)

A temperature-regulated iso-hyperbaric spectrophotometer: construction and performance characteristics

The position of an equilibrium is a function of pressure and temperature. Generally, only temperature effects are discussed for biochemical systems; however, pressure perturbations can offer interesting insights into the role of hydration in a reaction. We describe the construction and characteristics of an instrument that allows computer control of the temperature and pressure throughout the range -40 to +140 degrees C and 0.1 to 250 MPa, as well as automatic data acquisition from either a spectrophotometer or a spectrofluorimeter. To test the performance of the system the effect of pressure on the thermal denaturation of poly[d(A-T)] and poly(dA).poly(dT) has been investigated. In 20 mM NaCl, 20 mM Tris-HCl, pH 8.9, the delta V degrees for poly[d(A-T)] equals +0.30 +/- 0.09 cm3/mol (base pairs), and for poly(dA).poly(dT) delta V degrees equals +3.05 +/- 0.15 cm3/mol (base pairs). Although we focus on the use of this instrument to measure thermal denaturation curves, it can be employed to study the equilibrium of any reaction that can be followed optically in the ultraviolet or visible.

Use of the polymerase chain reaction for screening and evaluation of recombinant baculovirus clones

We report the application of the PCR for screening and high-resolution characterization of recombinant baculovirus clones. Starting with less than 10 nanograms of viral DNA, it is possible to 1) demonstrate that the DNA sequence to be expressed has not been deleted or rearranged during the co-transfection or homologous recombination events, 2) test for the presence of wild-type virus in the isolate and 3) generate amplified DNA that can be used for nucleotide sequence analysis or high-resolution restriction analysis. The method is based upon PCR of genomic viral DNA prepared from primary amplified stocks of extracellular virus using a small-scale procedure. The approach has special relevance for definitive characterization of recombinant virus used to express point mutant proteins and for characterization of recombinant virus generated through use of mixed oligonucleotides or random mutagenesis.

[Study on "massage to activate the meridian" apparatus in the treatment of cholecystolithiasis]

This apparatus is designed in accordance with the doctrine and principles of traditional Chinese medicine and based on the theory of meridian and specific massage procedure in conjunction with the "Information Theory" and electron utilizing technique. It utilizes a programmed induction "Special Wave" to stimulate a series of acupuncture points, combined with administration of western drugs from a regime of "General Attack" treatment on the gallbladder stones, to enhance their evacuation. By stimulating the specific acupuncture points with this apparatus through the action of "Special Wave" strong contraction of the gallbladder can be elicitated. Experiments on dogs showed that under such stimulation the intra-gallbladder pressure can be increased 26 times, producing a jet of bile flow which facilitates the expulsion and evacuation of stones in the gallbladder. Method of use: first place a conductive rubber pad on the acupuncture point to be stimulated, then use a hand-held electrode to massage-stimulate the meridian. It is carried out forward and backward along the direction of meridian. The whole procedure is carried out under direct visualization with the help of ultrasonic B-scan. When dilatation of the common bile duct is observed, the hand-help electrode is used to perform push-compress massage on the meridian, and acupuncture points making the stones enter the common bile duct B-scan give proper orientation for the manipulation. This method has been tested clinically on 410 patients with good results. The evacuation rate of the gallbladder stones was 92.7% with complete evacuation achieved in 17.3%.(ABSTRACT TRUNCATED AT 250 WORDS)