Fear, Stress, Susceptibility, and Problematic Social Media Use Explain Motivation for COVID-19 Preventive Behaviors Among Patients With Stroke and Their Caregivers

The COVID-19 pandemic presented significant challenges for individuals who experienced stroke and their caregivers. It is essential to understand the factors affecting preventive behavior in these populations. Therefore, the present study examined the factors that influenced COVID-19 preventive behavior and motivation for COVID-19 vaccine uptake among patients with stroke and their caregivers. A cross-sectional study comprising 191 participants (81 patients with stroke and 110 caregivers) was carried out. Participants completed a survey assessing fear of COVID-19, stress, perceived susceptibility, problematic social media use, preventive behaviors, and motivation for vaccine uptake. Statistical analyses included descriptive statistics, Pearson correlations, and multiple linear regressions. Motivation for COVID-19 vaccine uptake was significantly positively correlated with problematic social media use (r = 0.225, P = .002), perceived susceptibility (r = 0.197, P = .008), and fear of COVID-19 (r = 0.179, P = .015), but negatively correlated with stress (r = -0.189, P = .010). Caregivers, compared to patients, showed a lower level of preventive behavior (standardized coefficient = -0.23, P = .017). Furthermore, higher levels of fear were associated with increased preventive behavior (standardized coefficient = 0.22, P = .006), while greater stress correlated with lower preventive behavior (standardized coefficient = -0.38, P < .001). Among patients with stroke and their caregivers, motivation of COVID-19 vaccine uptake and preventive behaviors were influenced by factors such as fear, perceived susceptibility, social media use, and stress. By using strategies such as targeted education, support, and communication campaigns, healthcare providers and policymakers may be able to enhance the well-being of patients with stroke and their caregivers during future pandemics.

BMI trajectory in adulthood in relation to all-cause and cause-specific mortality: A retrospective cohort study in Taiwan

A dynamic change of weight over time has been known as an important factor that impacts mortality risk. The aims of this study were to identify the heterogeneity of BMI trajectory groups and to examine the association of the trajectories of BMI and all-cause and cause-specific mortality. The data for this study were obtained from a large prospective cohort study in Taiwan between 1998 and 2019 that was linked to the National Death Registry for death information. The participants were stratified into four groups by age and gender; self-reported demographics and measured BMI data were used. We used group-based trajectory analysis to identify the distinct trajectories of changes in BMI. A Cox proportional hazards model was used to assess the hazard ratio (HR) of all-cause and cause-specific mortality risk. Data were analyzed in April 2020 and included 89,886 participants. Four trajectory groups were identified by the pattern of BMI change over time. Our study shows that different trajectories were associated with mortality. Our findings suggest that the mortality risk differs in each trajectory group and in each age and gender stratification. It appears that obesity is a protective factor in cancer-related mortality in females but not in males in group of old age participants; low-normal weight is a risk factor in respiratory-related mortality in all participants. Our findings can be used to suggest the appropriate BMI in each age and gender groups and thereby earlier health interventions can be taken to avoid mortality.

Translation and Validation of the Gaming Disorder Test and Gaming Disorder Scale for Adolescents into Chinese for Taiwanese Young Adults

PURPOSE

To translate and cross-culturally adapt the Gaming Disorder Test (GDT) and Gaming Disorder Scale for Adolescents (GADIS-A) for use in Taiwan and to validate their internal consistency, construct validity, measurement invariance, and convergent validity in Taiwanese young adults.

METHODS

The GDT and GADIS-A were translated into traditional (unsimplified) Chinese characters and culturally adapted according to standard guidelines. A sample of 608 Taiwanese university students were recruited online. All participants completed the GDT, GADIS-A, Internet Gaming Disorder Scale - Short Form (IGDS9-SF), and Depression Anxiety Stress Scale-21 (DASS-21). Internal consistency was assessed using Cronbach's α and McDonald's ω. Factor structure was examined using Confirmatory Factor Analysis (CFA). Measurement invariance in gender was assessed by three nested models in CFA. Convergent validity was determined by calculating Pearson's r among the GDT, GADIS-A, IGDS9-SF, and DASS-21.

RESULTS

The GDT and GADIS-A showed adequate internal consistency (both α and ω = 0.90). The CFA results supported a one-factor structure for the GDT and a two-factor structure for the GADIS-A. Measurement invariance across gender was supported for both the GDT and GADIS-A. The convergent validity of the GDT and GADIS-A were acceptable.

CONCLUSIONS

The Chinese versions of the GDT and GADIS-A are valid and reliable tools that can be used to assess gaming disorder in Taiwanese young adults. Measurement invariance across genders was supported for both tools. The convergent validity of the GDT and GADIS-A were also satisfactory.

The association of care burden with motivation of vaccine acceptance among caregivers of stroke patients during the COVID-19 pandemic: mediating roles of problematic social media use, worry, and fear

BACKGROUND

The aim of the present study was to investigate the relationship between care burden and motivation of COVID-19 vaccine acceptance among caregivers of patients who have experienced a stroke and to explore the mediating roles of social media use, fear of COVID-19, and worries about infection in this relationship.

METHODS

A cross-sectional survey study with 172 caregivers of patients who had experienced a stroke took part in a Taiwan community hospital. All participants completed the Zarit Burden Interview, Bergen Social Media Addiction Scale, Worry of Infection Scale, Fear of COVID-19 Scale, and Motors of COVID-19 Vaccine Acceptance Scale. Multiple linear regression model was applied to construct and explain the association among the variables. Hayes Process Macro (Models 4 and 6) was used to explain the mediation effects.

RESULTS

The proposed model significantly explained the direct association of care burden with motivation of COVID-19 vaccine acceptance. Despite the increased care burden associated with decreased vaccine acceptance, problematic social media use positively mediated this association. Moreover, problematic social media use had sequential mediating effects together with worry of infection or fear of COVID-19 in the association between care burden and motivation of vaccine acceptance. Care burden was associated with motivation of vaccine acceptance through problematic social media use followed by worry of infection.

CONCLUSIONS

Increased care burden among caregivers of patients who have experienced a stroke may lead to lower COVID-19 vaccines acceptance. Moreover, problematic social media use was positively associated with their motivation to get COVID-19 vaccinated. Therefore, health experts and practitioners should actively disseminate accurate and trustworthy factual information regarding COVID-19, while taking care of the psychological problems among caregivers of patients who have experienced a stroke.

Dynamic changes in quality of life, psychological status, and body image in women who underwent a mastectomy as compared with breast reconstruction: an 8-year follow up

BACKGROUND

Surgical decisions and methods of surgery highly influence long term QoL for breast cancer (BC) survivors. This study is aimed towards an exploration of the dynamic changes in quality of life (QoL), anxiety/depression status, and body image (BI) among women with BC who received a mastectomy compared with those receiving breast reconstruction (BR) within an 8-year follow-up period.

METHODS

Women with major BC surgeries were invited to complete the World Health Organization Quality of Life-Brief (WHOQOL-BREF), the European quality of life five dimensions questionnaire (EQ-5D), and a body image scale within 8 years of surgery. Kernel smoothing methods were applied to describe dynamic changes in QoL, anxiety/depression, and BI at different time points. Linear mixed effects models were constructed to identify the interaction between time, different types of surgery, and the determinants of QoL in these patients.

RESULTS

After 1:10 propensity score matching, a total of 741 women who had undergone a BR and mastectomy were included. The BR group exhibited a high WHOQOL QoL score one to five years after surgery with some fluctuations. The mastectomy group had comparatively stable QoL scores on WHOQOL items and were less depressed/anxious. The BR group generally showed fluctuating, higher BI scores two years after surgery, but they exhibited more anxiety/depression during follow up for 8 years. Medical comorbidities, the status of anxiety/depression, and BI were the major factors influencing all domains and items of the WHOQOL BREF among women with BC.

CONCLUSION

The mastectomy group showed a decreased trend toward depression in patients with BC. The BR group showed a significant improvement in QoL in the first 5 years with massive fluctuations. These findings should be considered and discussed in patient participatory decision-making and promotion of QoL for breast cancer survivors.

Clustering of Modifiable Behavioral Risk Factors and Their Association with All-Cause Mortality in Taiwan's Adult Population: a Latent Class Analysis

Background

Modifiable risk behaviors, such as smoking, diet, alcohol consumption, physical activity, and sleep, are known to impact health. This study aims toward identifying latent classes of unhealthy lifestyle behavior, exploring the correlations between sociodemographic factors, identifying classes, and further assessing the associations between identified latent classes and all-cause mortality.

Methods

For this study, the data were obtained from a prospective cohort study in Taiwan. The participants’ self-reported demographic and behavioral characteristics (smoking, physical activity, alcohol consumption, fruit and vegetable intake, and sleep) were used. Latent class analysis was used to identify health-behavior patterns, and Cox proportional hazard regression analysis was used to find the association between the latent class of health-behavior and all-cause mortality.

Results

A complete dataset was obtained from 290,279 participants with a mean age of 40 (12.4). Seven latent classes were identified, characterized as having a 100% likelihood of at least one unhealthy behavior coupled with the probability of having the other four unhealthy risk behaviors. This study also shows that latent health-behavior classes are associated with mortality, suggesting that they are representative of a healthy lifestyle. Finally, it appeared that multiple risk behaviors were more prevalent in younger men and individuals with low socioeconomic status.

Conclusions

There was a clear clustering pattern of modifiable risk behaviors among the adults under consideration, where the risk of mortality increased with increases in unhealthy behavior. Our findings can be used to design customized disease prevention programs targeting specific populations and corresponding profiles identified in the latent class analysis.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12529-021-10041-x.

Post-Traumatic Stress Disorder in Chinese Teachers during COVID-19 Pandemic: Roles of Fear of COVID-19, Nomophobia, and Psychological Distress

There are limited data concerning the prevalence of post-traumatic stress disorder (PTSD) among teachers. Therefore, the present study estimated the prevalence of PTSD among mainland Chinese teachers during the COVID-19 pandemic and to construct a model with mediation and moderation effects to explain the PTSD. Data collection was conducted in schools in the Jiangxi province between October and November 2020 among k-12 schoolteachers. An online survey, including five different psychometric scales, was used to collect data. All participants were assessed for PTSD using the Chinese version of the PTSD Checklist for DSM-5 (PCL-5). Hayes' PROCESS Model 8 was used to examine the potential factors explaining a higher PTSD scores. A total of 2603 teachers from k-12 schools participated. With the cutoff score at 31, the prevalence of PTSD was 12.3% but decreased to 1.0% when the cutoff score was at 49. Nomophobia moderated the effects of Fear of COVID-19 Scale on PTSD. The findings suggest that fear of COVID-19 among teachers leads to PTSD via psychological distress, highlighting the moderating effect of nomophobia in this association. Based on the study's findings, psychological interventions and educational training are needed to reduce fear among teachers at higher risk of developing PTSD.

The Prevalence of Post-traumatic Stress Disorder Symptoms, Sleep Problems, and Psychological Distress Among COVID-19 Frontline Healthcare Workers in Taiwan

The adverse effect of COVID-19 pandemic among individuals has been very disturbing especially among healthcare workers. This study aims to examine the prevalence of post-traumatic stress disorder (PTSD) symptoms, sleep problems, and psychological distress among COVID-19 frontline healthcare workers in Taiwan. Hence, a total of 500 frontline healthcare workers were recruited to participate in this cross-sectional study. They responded to measures on fear of COVID-19, depression, anxiety, stress, insomnia, PTSD, perceived stigma, and self-stigma. The results indicated a prevalence rate of 15.4% for PTSD symptoms, 44.6% for insomnia, 25.6% for depressive symptoms, 30.6% for anxiety symptoms, and 23.4% for stress among the participants. There were significantly positive interrelationships between all these variables. Anxiety symptoms and fear of COVID-19 predicted PTSD whereas symptoms of anxiety, fear of COVID-19, and stress predicted insomnia. The prevalence rates of the psychological problems reveal a worrying view of mental health challenges among Taiwanese frontline healthcare workers. Anxiety symptoms and fear of COVID-19 are the common predictive factors of PTSD and sleep problems suggesting that mental healthcare services for them may help prevent future occurrence of psychological problems by allaying fears of healthcare workers. Therefore, there should be mental healthcare services for healthcare workers during the COVID-19 pandemic.

Willingness of Taiwan's Healthcare Workers and Outpatients to Vaccinate against COVID-19 during a Period without Community Outbreaks

To control the spread of the novel coronavirus disease 2019 (COVID-19), COVID-19 vaccination has been quickly developed. However, the COVID-19 pandemic will not be controlled if the COVID-19 vaccination uptake willingness is low. Therefore, the study aim was to explore the COVID-19 vaccination uptake willingness among the outpatient population and healthcare workers in Taiwan during the worldwide pandemic period without community outbreaks. A cross-sectional survey was conducted among healthcare workers (HCWs; n = 500; mean age = 32.96 years) of National Cheng Kung University Hospital (NCKUH) and outpatients (n = 238; mean age = 34.43 years) arriving at NCKUH. We used an online survey conducted between September 24 and 21 November 2020, for healthcare workers, and between 27 October and 31 December 2020, for the outpatient sample. Information regarding willingness to receive vaccination, willingness to rapid test, fear of COVID-19, risk perception, and preventive behaviors was collected in both samples; information regarding willingness to care for patients was collected in healthcare workers. Willingness to receive vaccination was the main variable in the present study; willingness to rapid test, willingness to care for patients, fear of COVID-19, risk perception, and preventive behaviors were the secondary variables in the study. The factors associated with vaccination willingness were identified through logistic regression analysis. The participants' willingness to receive vaccination was low for both healthcare workers (23.4%) and the outpatient sample (30.7%). Similarly, their willingness to take rapid tests was low (23.6% for healthcare workers and 28.6% for outpatient sample). Risk perception (crude odds ratio (COR) = 1.29; 95% confidence interval (CI) = 1.03, 1.63), willingness to take rapid test (COR = 9.24; 95% CI = 5.76, 14.83), and preventive COVID-19 infection behaviors (COR = 2.32; 95% CI = 1.52, 3.56) were significant factors explaining the healthcare workers' willingness to receive vaccination. Willingness to take a rapid test (COR = 8.91; 95% CI = 4.71, 16.87) and preventive COVID-19 infection behaviors (COR = 1.69; 95% CI = 1.09, 2.60) were significant factors explaining the outpatient sample's willingness to receive vaccination. Willingness to vaccinate against COVID-19 among HCWs and outpatients is low due to the relatively safe status of COVID-19 infection in Taiwan. These findings can help policymakers advocate for the effectiveness of and provide transparent information on COVID-19 vaccination uptake in a country/region with a relatively safe COVID-19 outbreak status.

Synthesis of 3,6-diaryl-1H-pyrazolo[3,4-b]pyridines via one-pot sequential Suzuki–Miyaura coupling

A practical synthesis of diarylpyrazolo[3,4-b]pyridine derivatives by a combination of chemoselective Suzuki–Miyaura cross-coupling reactions was developed. The sequential arylation strategy can be performed in a one-pot manner without much loss of efficiency when compared to the corresponding stepwise synthesis. These conditions are applicable to the coupling of a wide variety of aryl and heteroaryl-boronic acids with pyrazolo[3,4-b]pyridines with high selectivity of the C3 over the C6 position, thus enabling the rapid construction of a diverse array of medicinally important diarylpyrazolo[3,4-b]pyridines.

An efficient method to produce diarylpyrazolo[3,4-b]pyridines derivatives via combination of chemoselective Suzuki–Miyaura cross-coupling reactions has been developed.

Does position of syndesmotic screw affect functional and radiological outcome in ankle fractures?

The optimum level of syndesmotic screw used in ankle fractures with a tibiofibular diastasis is not clear in the literature. In a retrospective cohort study, we evaluated the clinical and radiological outcomes in two groups of patients-those who had a syndesmotic screw placed through the syndesmosis itself (transsyndesmotic, 17 patients) and those who had a syndesmotic screw placed just above the syndesmosis (suprasyndesmotic, 19 patients). The study suggests that the two groups do not differ significantly in terms of clinical and radiological outcomes.

Anatomy of deer spine and its comparison to the human spine

The anatomical parameters of the thoracic and lumbar regions of the deer spine were evaluated and compared with the existing data of the human spine. The objective was to create a database for the anatomical parameters of the deer spine, with a view to establish deer spine as a valid model for human spine biomechanical experiments in vitro. To date, the literature has supported the use of both calf and sheep spines as a suitable model for human spine experiments as the difficulty in procuring the human cadaveric spines is well appreciated. With the advent of Bovine Spongiform Encephalopathy (BSE) and its likely transmission to human in form of new variant Creutzfeld Jakob disease (CJD), there is a slight risk of transmission to humans through food chain if proper precautions for disposal of specimen are not adhered to. There is also a significant risk of transmission through direct inoculation to the researchers (Wells et al. Vet. Rec., 1998:142:103-106), working with infected bovine and sheep spine. The deer spines are readily available and there are no reported cases of deer being carriers of prion diseases (Ministry of Agriculture, Fisheries and Food, 1998). Six complete deer spines were measured to determine 22 dimensions from the vertebral bodies, endplates, disc, pedicles, spinal canal, transverse and spinous processes, articular facets. This was compared with the existing data of the human spine in the literature. The deer and human vertebrae show many similarities in the lower thoracic and upper lumbar spine, although they show substantial differences in certain dimensions. The cervical spine was markedly different in comparison. The deer spine may represent a suitable model for human experiments related to gross anatomy of the thoracic and lumbar spine. A thorough database has been provided for deciding the validity of deer spine as a model for the human spine biomechanical in vitro experiments.

Biomechanics of cell interactions in shear fields

Cellular interactions play a key role in diverse biological processes within the cardiovascular system. Targeting of leukocytes to sites of inflammation is viewed as a multistage process of sequential involvement of distinct adhesion molecules on the leukocyte and endothelial cell (EC) surface that is dictated by the local fluid dynamic environment. For neutrophils, the initial contact and rolling along the vessel wall are mediated primarily by selecting. Subsequent firm adhesion requires activation of neutrophil P, integrins and binding to their ligand ICAM-1 on the EC surface. The final step of this cascade of events includes neutrophil transmigration to extravascular tissue space. The neutrophil model of emigration in inflammation has been extended and refined to account for monocyte and T cell interactions with ECs. Platelet adhesion to thrombogenic surfaces (i.e. immobilized von Willebrand factor) under flow follows the general principles of leukocyte extravasation. More specifically, platelet glycoprotein (GP) Ib alpha appears to mediate an initial selectin-like tethering platelet-vWf interaction, followed by alpha II beta beta 3 integrin activation and firm adhesion. Some of the signaling mechanisms associated with cellular interactions in inflammatory and thrombotic processes are discussed. These basic principles are also discussed in the context of tissue engineering research.

Triple helices formed at oligopyrimidine*oligopurine sequences with base pair inversions: effect of a triplex-specific ligand on stability and selectivity

Oligonucleotide-directed triple helix formation is mostly restricted to oligopyrimidine*oligopurine sequences of double helical DNA. An interruption of one or two pyrimidines in the oligopurine target strand leads to a strong triplex destabilisation. We have investigated the effect of nucleotide analogues introduced in the third strand at the site opposite the base pair inversion(s). We show that a 3-nitropyrrole derivative (M) discriminates G*C from C*G, A*T and T*A in the presence of a triplex-specific ligand (a benzo[e]pyridoindole derivative, BePI). N6-methoxy-2,6-diaminopurine (K) binds to an A*T base pair better than a T*A, G*C or C*G base pair. Some discrimination is still observed in the presence of BePI and triplex stability is markedly increased. These findings should help in designing BePI-oligonucleotide conjugates to extend the range of DNA sequences available for triplex formation.

Rational design of a triple helix-specific intercalating ligand

DNA triple helices offer new perspectives toward oligonucleotide-directed gene regulation. However, the poor stability of some of these structures might limit their use under physiological conditions. Specific ligands can intercalate into DNA triple helices and stabilize them. Molecular modeling and thermal denaturation experiments suggest that benzo[f]pyrido[3, 4-b]quinoxaline derivatives intercalate into triple helices by stacking preferentially with the Hoogsteen-paired bases. Based on this model, it was predicted that a benzo[f]quino[3,4-b]quinoxaline derivative, which possesses an additional aromatic ring, could engage additional stacking interactions with the pyrimidine strand of the Watson-Crick double helix upon binding of this pentacyclic ligand to a triplex structure. This compound was synthesized. Thermal denaturation experiments and inhibition of restriction enzyme cleavage show that this new compound can indeed stabilize triple helices with great efficiency and specificity and/or induce triple helix formation under physiological conditions.

Extension of the range of DNA sequences available for triple helix formation: stabilization of mismatched triplexes by acridine-containing oligonucleotides

Triple helix formation usually requires an oligopyrimidine*oligopurine sequence in the target DNA. A triple helix is destabilized when the oligopyrimidine*oligopurine target contains one (or two) purine*pyrimidine base pair inversion(s). Such an imperfect target sequence can be recognized by a third strand oligonucleotide containing an internally incorporated acridine intercalator facing the inverted purine*pyrimidine base pair(s). The loss of triplex stability due to the mismatch is partially overcome. The stability of triplexes formed at perfect and imperfect target sequences was investigated by UV thermal denaturation experiments. The stabilization provided by an internally incorporated acridine third strand oligonucleotide depends on the sequences flanking the inverted base pair. For triplexes containing a single mismatch the highest stabilization is observed for an acridine or a propanediol tethered to an acridine on its 3'-side facing an inverted A*T base pair and for a cytosine with an acridine incorporated to its 3'-side or a guanine with an acridine at its 5'-side facing an inverted G*C base pair. Fluorescence studies provided evidence that the acridine was intercalated into the triplex. The target sequences containing a double base pair inversion which form very unstable triplexes can still be recognized by oligonucleotides provided they contain an appropriately incorporated acridine facing the double mismatch sites. Selectivity for an A*T base pair inversion was observed with an oligonucleotide containing an acridine incorporated at the mismatched site when this site is flanked by two T*A*T base triplets. These results show that the range of DNA base sequences available for triplex formation can be extended by using oligonucleotide intercalator conjugates.

Molecular mechanisms of monocyte adhesion to interleukin-1beta-stimulated endothelial cells under physiologic flow conditions

This study identifies multiple pathways used by monocytes to adhere to 4-hour interleukin-1beta stimulated human umbilical vein endothelial cells under flow conditions. Physiologic shear stresses were simulated in a flow chamber with parallel plate geometry; quantitation of primary adhesion, secondary adhesion, and transmigration was performed using phase contrast videomicroscopy. Neuraminidase treatment of monocytes reduced primary interaction by 50%, whereas blocking L-selectin or very late antigen-4 showed significant but smaller effects (approximately 30% inhibition). However, a combined treatment against all three pathways was able to reduce interaction by 80%. Blocking beta2 and alpha4 integrin pathways together inhibited secondary/firm adhesion by 75%. Only 40% of firmly adherent monocytes transmigrated across the endothelial monolayer with significantly increased transmigration times when both beta2 and alpha4 integrins were blocked. These results demonstrate that monocytes can use multiple receptors to interact with endothelial cells at both primary and secondary adhesion stages, and that these pathways have to be blocked simultaneously for maximum inhibition.

Endothelial P-selectin and VCAM-1 each can function as primary adhesive mechanisms for T cells under conditions of flow

This study demonstrates that endothelial P-selectin and vascular cell adhesion molecule 1 (VCAM-1), but not intercellular adhesion molecule 1 (ICAM-1), are capable of supporting extensive primary adhesion of T cells under flow. To address this issue, we used human umbilical vein endothelial cells (HUVECs) stimulated with histamine, interleukin-4 (IL-4), or interferon-gamma (IFN-gamma) that provide essentially a P-selectin, VCAM-1, or ICAM-1 surface, respectively, in a physiologically relevant cell type. Monoclonal antibody (mAb) blockade studies were carried out to confirm the specificity of these adhesive interactions and rule out a number of other potentially important adhesion molecules. Quantitation of adhesion showed that almost all of the interacting T cells rolled on histamine-stimulated HUVECs or CHO-P cell monolayers. In contrast, approximately 20% of the total interacting T cells with 24-h IL-4-treated HUVECs were firmly adherent. mAb blocking experiments revealed that T cell adhesion to IL-4-treated HUVECs is alpha 4-VCAM-1 dependent. Furthermore, mAb 4B9 directed against domain 1 of VCAM-1 eliminated adhesion, suggesting that alpha 4 integrins may not interact with either the alternatively spliced domain 4 of VCAM-1 or fibronectin in this process. At a wall shear stress of 2 dyn/cm2, the mean T cell rolling velocities were significantly lower on 24-h IL-4-activated HUVECs (10.2 +/- 2.6 microgm/s) compared with either CHO-P cells (15.6 +/- 3.1 microm/s) or histamine-stimulated HUVECs (16.6 +/- 6.1 microm/s). ICAM-1, expressed on the surface of 24-h IFN-gamma-activated HUVECs pretreated with an anti-VCAM-1 mAb to eliminate any VCAM-1-dependent contribution, did not support T cell adhesion under shear conditions. Together these data indicate that T cell primary adhesion can be mediate d by both endothelial P-selectin and VCAM-1 but not ICAM-1. alpha 4 integrins are highly versatile molecules, capable of initiating T cell rolling interactions and mediating firm arrest on activated endothelium.

Quantitative effects of peripheral monocytes and nerve growth factor on CNS neural morphometric outgrowth parameters in vitro

Would healing of the central nervous system (CNS) is a complex process involving interactions between cells from both the vascular and the neural environments, extracellular matrix proteins, and a cocktail of agonistic and antagonistic bioactive molecules. Vascular cells, particularly peripheral monocytes and macrophages, are believed to play an important role in organizing and mediating CNS tissue reactions subsequent to penetrating injuries that compromise the blood-brain barrier. Although many investigators have studied the effect of macrophages and microglia (resident brain macrophages) on neural outgrowth, little is known regarding monocyte effects. We have combined tissue culture, video microscopy, and digital image processing and analysis to quantify morphometric parameters of neurons exposed to monocyte secretory products in vitro. The experimental system developed is simple in design but provides a quantitative understanding of cellular function and molecular mechanisms and has the ability to both study processes of graded complexity and relate cellular function to overall systems behavior. We evaluate the efficacy of the experimental model developed by measuring morphometric parameters of human neural cells (hNT cell line) in the presence of nerve growth factor (NGF). Results suggest that monocyte-conditioned media (MCM) increases neuron outgrowth parameters, such as neuritic output, mean arbor output, neurite branching, and effective cell diameter. Moreover, we show that the bioactive factor present in MCM is not IL-1 and the activity of the factor with respect to neural outgrowth is between that of 10 and 100 ng/ml NGF.

Hairpin formation in d-AAGCTTAAGCTT under high salt conditions shows unusual properties

The hairpin-duplex equilibria of the dodecamer d-AAGCTTAAGCTT and interaction of the duplex form with a pentapeptide, KGWGK, has been studied. UV thermal transitions are monophasic at low salt but biphasic at higher salt concentrations. At 10(-5) M or less oligomer concentration biphasic melting curves persist till 900 mM NaCl. The d(Tm)/d log(Na+) for the duplex form is 12 degrees C and for the hairpin is 18 degrees C. The delta H and delta S values for duplex formation are low (-25 K cal/mole and -59 Cal/mole respectively). KGWGK binds to the duplex form with a binding constant K = 3.4 x 10(5)M-1 measured from fluorescence quenching of tryptophan. These unusual results are markedly different from that reported for d-AGATCTAGATCT (Biochemistry 31, 6241-6245) and are discussed in terms of sequence dependence of loop folding and cruciform extrusion pathway of hairpin formation.

A 500 MHz proton NMR study of interaction of tripeptides Lys-Tyr-Lys and Lys-Phe-Lys with deoxydinucleotide d-CpG

The binding of di- and tetranucleotides with tri- and tetrapeptides containing Tyr, Trp, Phe having lysine on both ends has been studied using a 500 MHz proton NMR. The results show that d-CpG exists as a right-handed B-DNA structure with both sugars in 01'-endo sugar conformation and glycosidic bond angle as in anti domain. On binding to tripeptide Lys-Tyr-Lys, the Tyr ring protons shift upfield by 0.015 ppm at 285 degrees K, while the conformation of d-CpG remains unchanged. Change in chemical shift of Tyr and nucleotide protons decreases with temperature. This upfield shift is attributed to stacking with bases/base-pairs. The presence of intermolecular NOE's also supports this. Results of binding of d-CpG to Lys-Phe-Lys are similar to those with Lys-Tyr-Lys except that the chemical shift changes occur to a lesser extent. On comparing the results obtained with three different peptides, it is found that interaction decreases in the order Trp > Tyr > Phe which is similar to that found by theoretical energy calculations (reported elsewhere) and fluorescence measurements. The results also exhibit a specificity in recognition of these amino acid residues by dinucleotides.

Binding of oligopeptides to d-AGATCTAGATCT and d-AAGCTTAAGCTT: can tryptophan intercalate in DNA hairpins?

The interactions of three tryptophan-containing peptides, KWK, KGWK tert-butyl ester, and KGWGK, with two self-complementary dodecamers of the same base composition but different sequence were studied by UV, CD, and fluorescence spectroscopy. The oligonucleotides, d-AGATCTAGATCT and d-AAGCTTAAGCTT, contain tandem repeats of the recognition site for the restriction enzyme BglII in the former and HindIII in the latter. Thermal transition data in dilute solutions and in 0.01 M NaCl indicate these dodecamers to be present in hairpin forms. Binding of peptides to these hairpins was followed by tryptophan fluorescence quenching titrations at 10 mM Na+; the data suggest intercalation of the indole ring. The association constants for the peptide-oligonucleotide (PN) complexes are an order of magnitude higher (10(5) M) than those reported with polynucleotides [10(4) M; Rajeswari et al. (1987) Biochemistry 26, 6825]. The pentapeptide, KGWGK, discriminates between BglII and HindIII sequences with higher affinity for the HindIII dodecamer. The CD maximum of KGWGK, at 220 nm, is drastically diminished upon interaction with oligonucleotides. The ellipticity at 220 nm is halved at 10 times less P/N ratio with the HindIII dodecamer than the BglII dodecamer, suggesting stronger binding to the HindIII dodecamer. The results are discussed in terms of two different modes of binding of oligopeptides to the DNA hairpins.

Hairpin and duplex forms of a self-complementary dodecamer, d-AGATCTAGATCT, and interaction of the duplex form with the peptide KGWGK: can a pentapeptide destabilize DNA?

Ordered forms of a synthetic dodecamer, d-AGATCTAGATCT, a direct repeat of the BglII recognition sequence, have been investigated using UV, CD, and fluorescence spectroscopy. Complex hairpin-duplex equilibria are manifest in UV thermal transitions, which are monophasic in the presence of very low or high NaCl concentrations but distinctly biphasic at intermediate ionic strengths. In 100 mM NaCl, the 1/Tm vs 1n C curve has a reasonable positive slope, which yields delta H and delta S for duplex formation as -66.2 kcal/mol and -190 cal/mol, respectively. Interaction of the dodecamer in duplex form with a tryptophan-containing peptide, KGWGK, has also been investigated to test the "bookmark" hypothesis (Gabbay et al., 1976) under the uniform structural constraint of the oligonucleotide of defined sequence. CD spectra of the peptide (P), the oligonucleotide (N), and their mixtures at different P/N ratios show a dramatic change in peptide spectrum but little change in nucleic acid dichroism with peptide binding. The Tm of P-N complexes decreases with an increase in peptide binding and levels off at saturation binding of P/N = 2.0. The data are interpreted in terms of a groove-cum-intercalation mode of binding, where intercalation to the tryptophan side chain destabilizes the double helix. A Scatchard plot of the binding data is nonlinear, with best-fit values for an overall association constant K = 4.33 x 10(5) M-1, and the number of binding sites n = 3.23 when fitted to the site-exclusion model of binding.

A 500 MHz proton NMR study of stacking interactions: binding of tripeptide Lys-Tyr-Lys to tetradeoxynucleotide d-GpCpGpC

The complete sequential assignment and conformation of d-GpCpGpC in D2O has been determined from 1D NMR spectra at 285-320 K and room temperature 2D-COSY and NOESY spectra. The tetradeoxynucleotide exists primarily as a right handed double helix at 285 K, having Tm as 314 K. On binding to a tripeptide Lys-Tyr-Lys in a concentration equimolar to tetranucleotide duplex, the Tyr ring protons shift upfield by 0.14 ppm at 285 K. The increase in Tm on binding suggests stabilization of duplex. The existence of intermolecular NOEs between C4 sugar protons and Tyr alpha C and Lys alpha C protons give direct evidence of proximity of Tyr residue to the C4 base of d-GpCpGpC. The conformation of d-GpCpGpC remains unchanged on binding. The observed results are interpreted in terms of preferential stacking of aromatic ring of Tyr residue with proximal base-pair of d-GpCpGpC, stabilized by electrostatic interaction of Lysine side chains with backbone phosphates. This is in contrast to intercalculation of aromatic dyes within base-pairs resulting in a change in sugar conformation at the binding site.