Associations between food consumption/dietary habits and the risks of obesity, type 2 diabetes, and hypertension: a cross-sectional study in Jakarta, Indonesia

BACKGROUND/OBJECTIVES

This study aimed to assess the current mean daily intake of 10 food groups, analyze the sociodemographic factors associated with food consumption, and determine the associations between food consumption/dietary intake and the prevalence rates of obesity, type 2 diabetes (T2D), and hypertension (HTN) in Jakarta, Indonesia.

SUBJECTS/METHODS

A total of 600 participants aged 20-85 yrs were included in this cross-sectional study. Food consumption and dietary habits were assessed using a food frequency questionnaire. To determine the association between food consumption/dietary habits and the abovementioned diseases, logistic regression analysis was performed.

RESULTS

The average vegetable and fruit intake was lower, while sugar and salt consumption were higher than that recommended by Indonesia's national dietary guidelines. A high intake of ultra-processed foods (UPFs) was associated with young age, men, "single" status, a high education level, and employment with a high monthly income. Obesity and T2D were positively correlated with high intakes of cereals and tubers, UPFs, sugars, fats, and oils. Conversely, an inverse association was found between legume, vegetable, and fruit consumption and obesity risk. An inverse correlation was also observed between vegetable consumption and T2D risk. Moreover, a high salt intake was inversely correlated with fruit consumption in terms of HTN risk. Non-indulgence in habitual late-night snacking and refrainment from consuming more than one dish at each meal were also negatively related to the prevalence of obesity, T2D, and HTN. Inverse correlations were also observed between the prevalence rates of T2D and HTN and abstaining from adding sugar to beverages.

CONCLUSION

Foods high in fat, sugar, and sodium were strongly associated with the risks of obesity, T2D, and HTN. Additionally, poor eating habits were also associated with disease development.

The Longitudinal Effect of Ultra-Processed Food on the Development of Dyslipidemia/Obesity as Assessed by the NOVA System and Food Compass Score

SCOPE

Ultra-processing food (UPF) has been a nutrition and health interest. This study is aimed to investigate the association between UPF consumption and the risk of obesity or dyslipidemia.

METHODS AND RESULTS

This study is performed using an ongoing cohort study including 17 310 individuals aged ≥40 years in South Korea. UPF is categorized by the NOVA system and FCS, respectively. After an average 5-year follow-up, there is a positive association between NOVA-defined UPF and dyslipidemia. The risk of the Q4 group is almost 20% higher than that of the Q1 group (men, adjusted HR = 1.209 [95% CI 1.039-1.407], women, adjusted HR = 1.195 [95% CI 1.096-1.303]). Consuming high-FCS foods (less processed and healthier foods) show a lower risk for dyslipidemia in both sexes and lower obesity risk in women compared to low-FCS consumption (men, dyslipidemia, adjusted HR = 0.857 [95% CI 0.744-0.988]; women, dyslipidemia, adjusted HR = 0.919 [95% CI 0.850-0.993], obesity, adjusted HR = 0.759 [95% CI 0.628-0.916]).

CONCLUSION

Higher UPF intakes assessed by the NOVA system and FCS are associated with increased incidences of dyslipidemia and obesity. Furthermore, NOVA-defined UPF shows a statistically significant negative association with AMED score, indicating poor diet quality.

Collagen Hydrolysate from the Scales of Mozambique Tilapia (Oreochromis mossambicus) Improve Hair and Skin Health by Alleviating Oxidative Stress and Inflammation and Promoting Hair Growth and Extracellular Matrix Factors

Fish-derived collagen hydrolysate (CH) has shown promise in improving hair and skin health. Therefore, this study sought to comprehensively assess the effects of CH extracted from Mozambique tilapia (Oreochromis mossambicus) scales on hair and skin using in vitro and in vivo models. Human dermal papilla cells (hDPCs) were used for antioxidant and gene expression analyses, while C57BL/6 mice were orally administered CH for six weeks to assess hair growth patterns. The mice were divided into four groups: negative control (NC; distilled water), positive control (PC; 1 mg/kg finasteride), CH500 (500 mg/kg BW CH), and CH1000 (1000 mg/kg BW CH). CH mitigated catalase activity reduction in hDPCs, increased IGF-1 and VEGF levels, and decreased TGF-β1, TNF-α, and IL-1β expression. In vivo, CH treatment improved hair growth index, length, diameter, weight, and density. Scanning electron microscopy revealed reduced hair damage. Moreover, CH up-regulated IGF-1, VEGF, Elastin, and HAS2 mRNA expression while down-regulating TNF-α and IL-1β. CH enhanced hair shine, growth, and skin health while alleviating inflammation. These findings demonstrate the potential of CH in alleviating oxidative stress, promoting hair growth, and enhancing skin health, both in vitro and in vivo. Fish-derived CH offers a cost-effective and bioavailable option for improving hair and skin health.

Microinjury-Induced Tumor Necrosis Factor-α Surge Stimulates Hair Regeneration in Mice

INTRODUCTION

Tumor necrosis factor (TNF)-α released after follicular injury such as that caused by plucking plays a role in the activation of hair regeneration. Microneedle (MN) treatment is applied to the scalp to increase permeability and facilitate the delivery of any number of compounds. Because the MN treatment causes injury to the epidermis, albeit minor, we reasoned that this treatment would lead to a temporary TNF-α surge and thereby promote hair regeneration.

METHODS

To investigate the effects of MN-treatment-induced microinjury and TNF-α on hair growth, we used C57BL/6N mice which were divided into six experimental groups: three groups of 1) negative control (NC), 2) plucking positive control (PK), and 3) MN therapy system (MTS) mice; and three groups identical to above were treated with a TNF-α blocker for 3 weeks: 4) NCB, 5) PKB, and 6) MTSB group.

RESULTS

After injury, TNF-α surge occurred on day 3 in the PK group and on day 6 in the MTS group. Wnt proteins and VEGF expression were markedly increased in the PK group on day 3 and on day 6 in the MTS group compared to the NC group. Following wound healing, only MTS and PK groups displayed thickened epidermis and longer HF length. Within the 2 weeks following treatment, the rate of hair growth was much slower in the injured mice treated with the TNF-α blocker.

CONCLUSION

Our findings indicate that microinjury stimulates the wound-healing mechanism via TNF-α/Wnt/VEGF surge to induce hair growth, and that blocking TNF-α inhibits this growth process.

Hair-Growth-Promoting Effects of the Fish Collagen Peptide in Human Dermal Papilla Cells and C57BL/6 Mice Modulating Wnt/β-Catenin and BMP Signaling Pathways

Fish-derived collagen has recently emerged as an alternative collagen source with bioactive properties, including the enhancement of hair and skin health. It is also cost-effective and has high bioavailability, in addition to having fewer side-effects compared to collagen from porcine skin or bovine skin. Collagen peptides (CPs) extracted from the scales of Mozambique tilapia (Oreochromis mossambicus) reportedly promote hair and skin health. This study sought to evaluate the effects of CPs on hair growth using in vitro and in vivo models. CP significantly enhanced hair regrowth and the proliferation of human dermal papilla cells (hDPCs) in vitro. CP was orally administered to C57BL/6 mice for 6 weeks to confirm the hair-growth-promoting effects. The mice were divided into four groups: negative control (distilled water), positive control (1 mg/kg of finasteride), CP500 (500 mg/kg of CP), and CP1000 (1000 mg/kg of CP). CP treatment significantly enhanced the proliferation of hDPCs compared to 0.2 μM finasteride, in addition to enhancing hair regrowth. Particularly, CP1000 treatment achieved a hair-growth index similar to that of the PC. In H&E staining, the CP groups exhibited a high A/T ratio. Furthermore, CP increased the expression of hair growth factors (IGF-1, VEGF, krt27, Gprc5d, and Ki67) and decreased the growth inhibitory factor (TGF-β1). Furthermore, CP significantly upregulated the Wnt/β-catenin pathways and downregulated the BMP pathways. Therefore, these results indicate that CP could be used as food supplements and nutraceuticals for hair loss prevention as well as hair regrowth during alopecia.

Dietary antioxidant consumption and the risk of type 2 diabetes in South Korean adults: a prospective cohort study based on the Health Examinees study

OBJECTIVES

Antioxidants are common dietary compounds with multiple health benefits. This study aimed to identify the association between dietary antioxidant consumption and the incidence of type 2 diabetes (T2D) mellitus (defined using the Korean Diabetes Association criteria) in South Korean adults.

DESIGN

Baseline and follow-up data from the Health Examinees (HEXA) study, a large-scale community-based genomic cohort study conducted in South Korea SETTING: A South Korean community.

PARTICIPANTS

A total of 20 594 participants, aged 40-79 years, who participated in the baseline and follow-up surveys of the HEXA study were included. After an average of 5 years of follow-up, there were 332 men and 360 women with T2D.

RESULTS

Participants with the highest total flavonoid consumption (Q5) had a lower risk of T2D (men: HR 0.63; 95% CI 0.42 to 0.93; p value for trend=0.0169; and women: HR 0.54; 95% CI 0.438 to 0.78; p value for trend=0.0001) than those with the lowest consumption (Q1). Dietary total antioxidant capacity was significantly inversely associated with the development of T2D mellitus in women participants alone (HR 0.58; 95% CI 0.40 to 0.83; p value for trend=0.0004). Stratified analyses according to age and body mass index (BMI) showed that dietary total flavonoid consumption and total antioxidant capacity had a negative association with the development of T2D in women aged >52 years and women with BMI >25 kg/m².

CONCLUSIONS

Dietary flavonoid consumption and total antioxidant capacity were associated with a lower risk of T2D in South Korean adults, especially in women aged >52 years and overweight. The findings of this study may provide reference data for the modification of dietary guidelines for South Koreans.

Anti-Obesity and Antidiabetic Effects of Nelumbinis Semen Powder in High-Fat Diet-Induced Obese C57BL/6 Mice

Nelumbinis Semen (NS, the seeds of Nelumbo nucifera) extract is a traditional Korean medicine with anti-oxidant activity. The present study examined the anti-obesity and antidiabetic effects of NS powder in high-fat diet (HFD)-induced obese C57BL/6 mice. Mice (n = 8/group) were fed a normal diet (CON), HFD, HFD containing 5% NS powder (HFD-NS5%), or HFD containing 10% NS powder (HFD-NS10%) for 12 weeks. Food intake was relatively higher in groups HFD-NS5% and HFD-NS10%, while the food efficiency ratio was highest in group HFD (p < 0.05). HFD-NS5% reduced the body weight (-39.1%) and fat weight (-26.6%), including epididymal fat and perirenal fat, and lowered the serum triglyceride levels (-20.6%) compared with HFD. Groups HFD-NS5% and HFD-NS10% showed hepatoprotective properties, reducing the serum ALT levels (p < 0.05) and fat globules (size and number) in the liver compared with group HFD. HFD-NS5% and HFD-NS10% regulated the blood glucose, improved the glucose intolerance, and showed a 12.5% and 15.0% reduction in the area under the curve (AUC) of intraperitoneal glucose tolerance test (IPGTT), and a 26.8% and 47.3% improvement in homeostatic model assessment insulin resistance (HOMA-IR), respectively, compared with HFD (p < 0.05). Regarding the expressions of genes related to anti-obesity and antidiabetes, there was a 1.7- and 1.3-fold increase in PPAR-α protein expression, 1.4- and 1.6-fold increase in PPAR-γ protein expression, and 0.7- and 0.6-fold decrease in TNF-α protein expression, respectively, following HFD-NS5% and HFD-NS10% treatments, compared with HFD, and GLUT4 protein expression increased relative to CON (p < 0.05). These results comprehensively provide the fundamental data for NS powder's functional and health-promoting benefits associated with anti-obesity and antidiabetes.

Trends in Beverage Consumption and Related Demographic Factors and Obesity among Korean Children and Adolescents

It is well known that reducing consumption of sugar is a global public health priority. Beverages were the primary source of total sugar intake from processed foods. However, there are few studies investigating the trend of beverage consumption among children and adolescents in Korea. We examined the overall trend in beverage consumption among 11,996 participants aged 10-18 years who were enrolled in the Korea National Health and Nutrition Examination Survey (KNHANES) (1998-2018). Further, we examined the effect of beverage types on beverage consumption-related demographic factors and obesity among 6121 participants using the recent 24 h dietary recall data (2010-2018) that captured the consumption of fruit and vegetable juices, soft drinks, milk and milk-based products and alcoholic beverages. Demographic characteristics, including sex, age, body mass index, household income level and residential area, were considered. Consumers' overall beverage intake and the percentage of energy derived from fruit and vegetable juices and soft drinks steadily increased from 1998 to 2016-2018 (p-trend < 0.0001); in contrast, dairy product consumption declined since 2010-2012. The main sources of beverage-based calories were fruit and vegetable juices (107.5 kcal/day), soft drinks (145.2 kcal/day), dairy products (181.8 kcal/day) and alcoholic beverages (103.5 kcal/day). Also, Korean adolescents aged 16-18 years consumed more soft drinks, fewer dairy products and higher alcoholic drinks than other age groups; particularly, boys consumed more energy from beverages (p < 0.0001). The odds ratios of obesity prevalence tended to be higher for soft drink consumption than for other beverages but this was not significant. The consumption of fruit and vegetable juices and milk and milk products showed a marginal association with a reduced risk of obesity prevalence. Since beverage consumption has increased steadily among Korean children and adolescents, appropriate interventions are needed. In the future, data from a larger sample of Korean children and adolescents are necessary to identify significant differences and longitudinal studies are necessary to examine the causalities.

Associations between Cerebral Embolism and Carotid Intraplaque Hemorrhage during Protected Carotid Artery Stenting

BACKGROUND AND PURPOSE

Carotid artery stent placement in patients with intraplaque hemorrhage remains controversial because of the incidence of cerebral embolism after the procedure. The purpose of this study is to determine if intraplaque hemorrhage is a significant risk factor for cerebral embolism during carotid artery stent placement.

MATERIALS AND METHODS

This prospective study assessed 94 consecutive patients with severe carotid stenosis. These patients underwent preprocedural carotid MR imaging and postprocedural DWI after carotid artery stent placement. Intraplaque hemorrhage was defined as the presence of high signal intensity within the carotid plaque that was >200% of the signal from the adjacent muscle on MPRAGE. We then analyzed the incidence of postprocedural ipsilateral ischemic events on DWI and primary outcomes within 30 days of carotid artery stent placement.

RESULTS

Forty-three patients (45.7%) had intraplaque hemorrhage on an MPRAGE image. There was no significant difference in the incidence of postprocedural ipsilateral ischemic events and primary outcomes between the intraplaque hemorrhage and non-intraplaque hemorrhage group. However, postprocedural ipsilateral ischemic events were more frequently observed in the symptomatic group (17/41 [41.5%]) than in the asymptomatic group (8/53 [15.1%]; P = .005).

CONCLUSIONS

Intraplaque hemorrhage was not a significant risk factor for cerebral embolism during carotid artery stent placement in patients with severe carotid stenosis. Symptomatic patients should receive more careful treatment during carotid artery stent placement because of the higher risk of postprocedural ipsilateral ischemic events.

SUMOylation of nonstructural 5A protein regulates hepatitis C virus replication

Viruses exploit cellular SUMOylation machinery to favour their own propagation. We show that NS5A is a target protein of small ubiquitin-like modifier (SUMO) and is SUMOylated at lysine residue 348. We demonstrated that SUMOylation increased protein stability of NS5A by inhibiting ubiquitylation, and SUMOylation was also required for protein interaction with NS5B. These data imply that SUMO modification may contribute to HCV replication. Indeed, silencing of UBC9 impaired HCV replication in Jc1-infected cells, and HCV replication level was also significantly reduced in SUMO-defective subgenomic replicon cells. Taken together, these data indicate that HCV replication is regulated by SUMO modification of NS5A protein. We provide evidence for the first time that HCV exploits host cellular SUMO modification system to favour its own replication.

Predictors of functional outcome after emergency carotid artery stenting and intra-arterial thrombolysis for treatment of acute stroke associated with obstruction of the proximal internal carotid artery and tandem downstream occlusion

BACKGROUND AND PURPOSE

Patients who develop severe stroke symptoms due to acute internal carotid artery occlusion eventually in combination with a thromboembolic obstruction of the middle cerebral artery incur a major risk of developing extensive MCA infarction with a poor outcome. The purpose of this study was to evaluate the outcome for patients with tandem occlusions in the MCA and/or distal ICA, retrospectively, who had undergone stent implantation in the proximal segment of the ICA in addition to intra-arterial thrombolysis.

MATERIALS AND METHODS

Thirty-five patients with tandem occlusions of the MCA and/or distal ICA and acute occlusion of the proximal ICA underwent stent implantation for the proximal ICA occlusion and IAT for the tandem occlusion. Clinical outcome measures were assessed on admission and at discharge by using the National Institutes of Health Stroke Scale as well as 3 months after treatment by using the modified Rankin Scale.

RESULTS

The median NIHSS score on admission was 12 (range, 6-22). All patients had patent flow into the M1 and ICA after carotid artery stent placement and IAT. After the procedure, 19 patients (54.3%) were TICI grade III; 7 (20.0%), TICI grade IIb; and 9 (25.7%), TICI grade IIa. Symptomatic intracerebral hemorrhage occurred in 1 patient (2.9%). The overall mortality rate was 11.4% (4/35). At 3-month follow-up, the median NIHSS score was 4 (range, 1-17). NIHSS score at admission and TICI grade were all found to be independently associated with an unfavorable outcome at 3 months.

CONCLUSIONS

Initial stroke severity, degree of successful revascularization, and the side of ischemia were found to independently predict the functional outcome at 3 months after treatment.

Nonstructural 5A protein of hepatitis C virus regulates heat shock protein 72 for its own propagation

We identified heat shock protein 72 (Hsp72) as a host factor that was differentially expressed in cells expressing nonstructural 5A (NS5A) protein. To investigate how NS5A modulates Hsp72 in hepatitis C virus (HCV) life cycle, we examined the role of Hsp72 in HCV replication and virus production. NS5A specifically interacted with Hsp72. Both Hsp72 and nuclear factor of activated T cells 5 (NFAT5) levels were increased in cells expressing NS5A protein. Treatments of N-acetylcysteine and glutathione markedly reduced protein levels of both NFAT5 and Hsp72. Knockdown of NFAT5 resulted in decrease in Hsp72 level in cells expressing NS5A. Importantly, silencing of Hsp72 expression resulted in decrease in both RNA replication and virus production in HCV-infected cells. These data indicate that NS5A modulates Hsp72 via NFAT5 and reactive oxygen species activation for HCV propagation.

Balloon-expandable stent placement in patients with immediate reocclusion after initial successful thrombolysis of acute middle cerebral arterial obstruction

We present the results of our approach for treating 12 consecutive cases of acute middle cerebral artery (MCA) stroke by performing balloon-expandable stent (BES) placement after immediate reocclusion due to the underlying stenosis after intra-arterial thrombolysis (IAT). We retrospectively reviewed the clinical outcomes of 12 patients with acute MCA stroke who underwent recanalization by BES placement in an underlying stenosis after IAT. The time to treatment, urokinase dose, duration of the procedure, recanalization rates and symptomatic hemorrhage were analyzed. Clinical outcome measures were assessed on admission and at discharge (the National Institutes of Health stroke scores [NIHSS]) as well as three months after treatment (modified Rankin scales [mRS]). The median NIHSS score on admission was 8.6. Four patients received IV rtPA. The median time from symptom onset to IAT was 236 minutes and the median duration of IAT was 62 minutes. The median dose of urokinase was 140,000 units. Initial recanalization after stent deployment (thrombolysis in cerebral ischemia attack grade of II or III) was achieved in all patients. Two patients died in the hospital due to aspiration pneumonia during medical management. In two patients, in-stent reocclusion occurred within 48 hours after stent deployment. At discharge, the median NIHSS score in ten patients (including the patients with reobstruction) was 2.4. The three-month outcome was excellent (mRS, 0-1) in eight patients. In this study, BES deployment was safe and effective in patients with an immediately reoccluded MCA after successful IAT.

Endovascular management in patients with acute basilar artery obstruction: low-dose intra-arterial urokinase and mechanical clot disruption

Mechanical clot disruption for the treatment of acute basilar artery occlusion (BAO) is known to provide a benefit. We aimed to determine the safety, recanalization rate and time-to-flow restoration of mechanical clot disruption and low dose urokinase (UK) infusions for the treatment of patients with acute BAO. Between June 2006 and June 2010, 21 patients with acute BAO underwent endovascular treatment that included angioplasty or stent placement. The time to treatment, duration of the procedure, dose of urokinase (UK), recanalization rates and symptomatic hemorrhages were analyzed. Clinical outcome measures were assessed at admission and at the time of discharge using the National Institutes of Health Stroke Scale (NIHSS) score and at three months after treatment using the modified Rankin Score (mRS). On admission, the median NIHSS score was 13.2. Median time from symptom onset to arrival at hospital was 356 minutes, and median time from symptom onset to intraarterial thrombolysis (IAT) was 49 minutes. We used the following interventional treatment regimens: Intra-arterial (IA) UK and a minimal mechanical procedure (n=14), IA UK with angioplasty (n=1), IA UK with angioplasty and stent placement (n=3) and IA UK with HyperForm (n=3). The recanalization (thrombolysis in cerebral ischemia grade II or III) rate was 90.5% (19/21). There was symptomatic hemorrhage in one patient (4.8%). The median NIHSS score at discharge was 6.3. The three-month outcome was favorable (mRS: 0-2) for 14 patients (66.7%) and poor (mRS: 3-6) for seven patients (33.3%). The overall mortality at three months was 14.3% (three patients died). Low-dose IAT with mechanical clot disruption is a safe and effective treatment for treatment for acute BAO.

Diagnostic efficacy of gadoxetic acid-enhanced MRI in the detection of hepatocellular carcinomas: comparison with gadopentetate dimeglumine

This study compared the efficacy of gadoxetic acid-enhanced MRI and gadopentetate dimeglumine-enhanced MRI in the detection of small hepatocellular carcinoma (HCC). Both MRI techniques were performed on 43 patients with a total of 59 HCCs (size range, 0.5-2.0 cm), with a mean interval between the two MRI studies of 3 days (range, 2-7 days). Two observers reviewed both data sets in consensus. Diagnostic accuracy and sensitivity were evaluated using the alternative-free response receiver operator characteristic (ROC) method. The gadoxetic acid set showed a trend toward increased area under the ROC curve (Az value = 0.958) compared with the gadopentetate dimeglumine set (Az value = 0.927), but the difference was not significant (p = 0.362). The sensitivity of the gadoxetic acid set (n = 51, 86.4%) was significantly higher than that of the gadopentetate dimeglumine set (n = 38, 64.4%) (p = 0.0001). Gadoxetic acid-enhanced MRI is a more sensitive diagnostic tool for detection of HCC than gadopentetate dimeglumine-enhanced MRI.

Monoclonal antibody recognizing N-terminal epitope of hepatitis C virus nonstructural 5B inhibits viral RNA replication

The nonstructural 5B (NS5B) protein of hepatitis C virus (HCV) is an RNA-dependent RNA polymerase (RdRp) with a key role in HCV replication. To characterize the functional roles of NS5B in HCV replication, we produced a panel of 10 monoclonal antibodies (mAbs) directed against NS5B protein from mice immunized with functionally active RdRp. The epitopes of eight mAbs are localized in the middle region (amino acid 240-263) of NS5B protein. On the other hand, the epitopes of two mAbs are mapped to amino acids 67-88 at the N-terminus of NS5B protein. To examine the effects of mAbs on HCV-RNA replication, we performed in vitro RdRp assay using either the 3'-untranslated region (UTR) or the full-length of HCV-RNA as a template in the presence of each mAb. mAbs specific for the middle region of NS5B had no effect on RdRp activity. Surprisingly, mAb recognizing the N-terminal region of NS5B inhibited RdRp activity in a dose-dependent manner. We have confirmed the same result using the other subclass of mAb, whose epitope is also localized to the same N-terminal region of NS5B. These data show that NS5B contains a B-cell epitope located between amino acid residues 67 and 88. Binding of this epitope with an antibody interferes with the enzymatic function of NS5B.

Anti-inflammatory activities of LDP-392, a dual PAF receptor antagonist and 5-lipoxygenase inhibitor

Leukotrienes (LTs) and platelet-activating factor (PAF) are important mediators of inflammation and allergy. LDP-392, a novel dual PAF receptor antagonist and 5-lipoxygenase (5-LO) inhibitor, has been identified. LDP-392 is 17.9-fold more potent than zileuton (5-LO inhibitor) in the RBL cytosolic 5-LO assay, and equally potent as MK 287 (PAF receptor antagonist) in the human platelet PAF receptor binding assay. The in vivo dual activities of LDP-392 were confirmed by measuring the inhibition of ex vivo LTB(4)production in rats and PAF-induced hemoconcentration in mice. Intravenous administration of LDP-392 demonstrated greater inhibition than zileuton, BN 50739 or MK 287 on arachidonic acid-induced ear edema and protected mice from LPS-induced lethality. Topical administration of LDP-392, in a dose-dependent manner, inhibited TPA-induced ear edema in mice and UVB-induced erythema in guinea-pigs. These data suggest that LDP-392, as a dual PAF receptor antagonist and 5-LO inhibitor, may be of greater clinical effectiveness.

Hepatitis C virus core protein potentiates TNF-alpha-induced NF-kappaB activation through TRAF2-IKKbeta-dependent pathway

Previous work has implicated that the core protein of hepatitis C virus (HCV) may play a modulatory effect on NF-kappaB activation induced by TNF-alpha. However, it is unclear how HCV core protein modulates TNF-alpha-induced NK-kappaB activation. Here we show that overexpression of HCV core protein potentiates NF-kappaB activation induced by TNF-alpha. Expression of dominant negative form of TRAF2 inhibits the synergistic effects of HCV core protein on NF-kappaB activation, suggesting that HCV core protein potentiates NF-kappaB activation through TRAF2. Moreover, we demonstrate that HCV core protein potentiates TRAF2-mediated NF-kappaB activation via IKKbeta. In addition, HCV core protein associates with TNF-R1-TRADD-TRAF2 signaling complex, resulting in synergistically activation of NF-kappaB induced by TNF-alpha. Thus, these observations indicate that HCV core protein may play an important role in the regulation of the cellular inflammatory and immune responses through NF-kappaB.

Hepatitis C virus core protein potentiates c-Jun N-terminal kinase activation through a signaling complex involving TRADD and TRAF2

The hepatitis C virus (HCV) core protein is a multifunctional viral nucleocapsid protein. Previously, it has been demonstrated that the HCV core protein interacts with the cytoplasmic domain of tumor necrosis factor receptor 1 (TNFR1). Since the TNFR1 is engaged in stimulation of transcriptional factor NF-kappaB and AP-1 through activation of IkappaB kinase and c-Jun N-terminal kinase (JNK, or stress-activated protein kinase), respectively, we have examined whether the interaction between core protein and TNFR1 can modulate JNK. In this study, we demonstrate that the HCV core protein synergistically activates TNFalpha-induced JNK at a core concentration dependent manner in human embryonic kidney (HEK) 293 cells. HCV core-mediated synergism of JNK activation was also detected in stable cells expressing HCV core protein. Furthermore, we demonstrate that HCV core protein does not compete with TNF receptor-associated death domain (TRADD) for its interaction with the death domain of TNFR1. Our in vivo data show that HCV core and TRADD form a ternary complex with TNFR1. These findings suggest that the HCV core protein modulates TNFR1 signaling and may, thus, play a role in chronic infection of HCV patients.

Characterization and translational regulation of the arginine decarboxylase gene in carnation (Dianthus caryophyllus L.)

Arginine decarboxylase (ADC; EC 4.1.1.9) is a key enzyme in polyamine biosynthesis in plants. We characterized a carnation genomic clone, gDcADC8, in which the deduced polypeptide of ADC was 725 amino acids with a molecular mass of 77.7 kDa. The unusually long 5'-UTR that contained a short upstream open reading frame (uORF) of seven amino acids (MQKSLHI) was predicted to form an extensive secondary structure (free energy of approximately -117 kcal mol-1) using the Zuker m-fold algorithm. The result that an ADC antibody detected two bands of 45 and 33 kDa in a petal extract suggested the full length of the 78 kDa polypeptide precursor converted into two polypeptides in the processing reaction. To investigate the role of the transcript leader in translation, in vitro transcription/translation reactions with various constructs of deletion and mutation were performed using wheat germ extract. The ADC transcript leader affected positively downstream translation in both wheatgerm extract and primary transformant overexpressing ADC gene. It was demonstrated that heptapeptide (8.6 kDa) encoded by the ADC uORF was synthesized in vitro. Both uORF peptide, and the synthetic heptapeptide MQKSLHI of the uORF, repressed the translation of downstream ORF. Mutation of the uORF ATG codon alleviated the inhibitory effect. ORF translation was not affected by either a frame-shift mutation in uORF or a random peptide. To our knowledge, this is the first report to provide evidence that a uORF may inhibit the translation of a downstream ORF, not only in cis but also in trans, and that the leader sequence of the ADC gene is important for efficient translation.

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

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

Cell cycle arrest mediated by hepatitis delta antigen

Hepatitis delta antigen (HDAg) is the only viral-encoded protein of the hepatitis delta virus (HDV). This protein has been extensively characterized with respect to its biochemical and functional properties. However, the molecular mechanism responsible for persistent HDV infection is not yet clear. Previously, we reported that overexpression of HDAg protects insect cells from baculovirus-induced cytolysis [Hwang, S.B. Park, K.-J. and Kim, Y.S. (1998) Biochem. Biophys. Res. Commun. 244, 652-658]. Here we report that HDAg mediates cell cycle arrest when overexpressed in recombinant baculovirus-infected insect cells. Flow cytometry analysis has shown that HDAg expression in Spodoptera frugiperda cells causes an accumulation of substantial amounts of polyploid DNA in the absence of cell division. This phenomenon may be partly responsible for the persistent infection of chronic HDV patients.

Characterization of mRNA for hepatitis delta antigen: exclusion of the full-length antigenomic RNA as an mRNA

Hepatitis delta virus (HDV) encodes a single protein, the hepatitis delta antigen (HDAg), which is thought to be translated from a 0. 8-kb RNA of antigenomic sense. This subgenomic RNA species is present in very small amounts in HDV-infected liver tissues and in cultured cells infected or transfected with HDV, and in some cases it cannot be detected at all. In contrast, HDAg protein is present in large amounts in all natural and experimental models of HDV infection. This study addresses whether other HDV RNA species, such as the antigenomic-sense, genome-size HDV RNA can also serve as the mRNA for HDAg synthesis. Taking advantage of the ability of herpes simplex virus (HSV) to degrade only polyadenylated mRNAs, we examined the effect of HSV coinfection on HDAg synthesis. It was shown that HSV infection did degrade the subgenomic 0.8-kb HDV mRNA but not HDV genome-length RNA. Under such conditions, HDAg synthesis was completely inhibited. Furthermore, the genome-length HDV RNA was found not to be associated with polysomes. Finally, in vitro translation studies demonstrated that HDAg could not be translated directly from the genome-length antigenomic-sense HDV RNA. These results suggest that only the subgenomic RNA species of HDV possesses properties characteristic of the mRNA for HDAg and that the genome-length RNA cannot be used for translating HDAg. In addition, we found that HDV RNA replication did not depend on de novo HDAg synthesis.

Hepatitis C virus core protein interacts with heterogeneous nuclear ribonucleoprotein K

Hepatitis C virus (HCV) core protein, a component of viral nucleocapsid, has been shown to modulate cellular and viral promoter activities. To identify potential cellular targets for HCV core protein, a human liver cDNA library was screened for core-interacting proteins using the yeast two-hybrid system. Among the proteins identified was heterogeneous nuclear ribonucleoprotein K (hnRNP K), which has been demonstrated to be a transcriptional regulator. The interaction of HCV core protein with hnRNP K was confirmed by glutathione S-transferase fusion protein binding assay, protein-protein blotting assay, and coimmunoprecipitation in vitro and in vivo. Additionally, these two proteins were shown to be partially colocalized in the nucleus. The hnRNP K-binding site in HCV core protein was mapped to the region from amino acid residues 25-91, a hydrophilic area near the N terminus. The HCV core protein-binding domain was located within amino acid residues 250 to 392, which contain the three proline-rich domains, of hnRNP K. Furthermore, HCV core protein relieved the suppression effect of hnRNP K on the activity of the human thymidine kinase gene promoter. The specific binding of HCV core protein to hnRNP K suggests that multiple functions of hnRNP K may be disrupted by the core protein during HCV infection and thus explains, in part, the pathogenesis of HCV.

(+/-)-trans-2-[3-methoxy-4-(4-chlorophenylthioethoxy)-5-(N-methyl-N- hydroxyureidyl)methylphenyl]-5-(3,4, 5-trimethoxyphenyl)tetrahydrofuran (CMI-392), a potent dual 5-lipoxygenase inhibitor and platelet-activating factor receptor antagonist

By incorporating an N-hydroxyurea functionality onto diaryltetrahydrofurans, a novel series of compounds was investigated as dual 5-lipoxygenese (5-LO) inhibitor and platelet-activating factor (PAF) receptor antagonist. These dual functional compounds were evaluated in vitro for 5-LO inhibition in RBL cell extracts and human whole blood, and PAF receptor antagonism in a receptor binding assay. PAF-induced hemoconcentration and arachidonic acid- and TPA-induced ear edema in mice were used to determine in vivo activities. The structure-activity relationship analysis to define a preclinical lead is presented. (+/-)-trans-2-[3-methoxy-4-(4-chlorophenylthioethoxy)-5-(N-methyl- N-h ydroxyureidyl)methylphenyl]-5-(3,4, 5-trimethoxyphenyl)tetrahydrofuran (40, CMI-392) was selected for further study. In the arachidonic acid-induced mouse ear edema model, 40 was more potent than either zileuton (a 5-LO inhibitor) or BN 50739 (a PAF receptor antagonist), and it demonstrated the same inhibitory effect as a physical combination of the latter two agents. These results suggest that a single compound which both inhibits leukotriene synthesis and blocks PAF receptor binding may provide therapeutic advantages over single-acting agents. The clinical development of compound 40 is in progress.

TR4 orphan receptor crosstalks to chicken ovalbumin upstream protein-transcription factor and thyroid hormone receptor to induce the transcriptional activity of the human immunodeficiency virus type 1 long-terminal repeat

Here we investigate the roles of human testicular orphan receptors, TR2 and TR4, on the gene regulation of the long-terminal repeat of the human immunodeficiency virus type 1 (HIV-LTR). In gel-retardation assays, a palindromic element at the 5'-end of HIV-LTR,5'-AGGGGTCAGATATCCACTGACCTTT-3',showed high affinity to TR2 and TR4 with an equilibrium dissociation constant (Kd) of 1.11 +/- 0.48 (n = 3) and 0.52 +/- 0.12 nM (n = 3), respectively. Interestingly, each half-site of the palindromic element is sufficient to compete with the binding of the labeled palindromic element to TR2 or TR4 with an equilibrium inhibition constant (ki) around 10 nM. However, the transiently expressed TR2 or TR4 in Chinese hamster ovary (CHO) cells or Japanese quail muscle myoblasts (QM7) cells showed no activity in regulating the transcriptional activity of the chloramphenicol acetyltransferase (CAT) reporter gene inserted downstream of the HIV-LTR promoter. Although both TR2 and TR4 showed no effect on CAT activity by itself, our data showed only the TR4 could crosstalk to the chicken ovalbumin upstream protein-transcription factor (COUP-TF1) and thyroid hormone receptor (TR alpha 1), and potentiated the transcriptional activity of HIV-LTR on the CAT reporter gene regulated by COUP-TF1 and TR alpha 1. These results indicate that TR4, but not TR2, may couple to other nuclear receptors in the upregulation of the HIV replication.

Hepatitis C virus core from two different genotypes has an oncogenic potential but is not sufficient for transforming primary rat embryo fibroblasts in cooperation with the H-ras oncogene

Persistent infection with hepatitis C virus (HCV) is associated with the development of liver cirrhosis and hepatocellular carcinoma. To examine the oncogenic potential of the HCV core gene product, primary rat embryo fibroblasts (REFs) were transfected with the core gene in the presence or absence of the H-ras oncogene. In contrast to a previous report (R. B. Ray, L. M. Lagging, K. Meyer, and R. Ray, J. Virol. 70:4438-4443, 1996), HCV core proteins from two different genotypes (type 1a and type 1b) were not found to transform REFs to tumorigenic phenotype in cooperation with the H-ras oncogene, although the core protein was successfully expressed 20 days after transfection. In addition, REFs transfected with E1A- but not core-expressing plasmid showed the phenotype of immortalized cells when selected with G418. The biological activity was confirmed by observing the transcription activation from two viral promoters, Rous sarcoma virus long terminal repeat and simian virus 40 promoter, which are known to be activated by the core protein from HCV-1 isolate. In contrast to the result with primary cells, the Rat-1 cell line, stably expressing HCV core protein, exhibited focus formation, anchorage-independent growth, and tumor formation in nude mice. HCV core protein was able to induce the transformation of Rat-1 cells with various efficiencies depending on the expression level of the core protein. These results indicate that HCV core protein has an oncogenic potential to transform the Rat-1 cell line but is not sufficient to either immortalize primary REFs by itself or transform primary cells in conjunction with the H-ras oncogene.

Overexpression of hepatitis delta antigen protects insect cells from baculovirus-induced cytolysis

Hepatitis delta virus (HDV) is a human pathogen causing fulminant hepatitis and liver cirrhosis. HDV has a circular single-stranded RNA genome, which encodes only a single protein, hepatitis delta antigen (HDAg), from the antigenomic strand. Although the functional roles of HDAg have been extensively studied, the molecular mechanism of persistent infection and pathogenesis of HDV are not yet understood. Here we report that overexpressed HDAg protects cells from death in baculovirus-infected insect cells. Using both wild-type and recombinant baculovirus-infected insect cells, we have demonstrated that HDAg inhibited wild-type baculovirus-induced cytolysis and thus extended the survival of virus-infected insect cells. By deletion analysis, we show that N-terminal 25 amino acids are essential for this function. From these data, we suggest that HDAg may play a major role in persistent infection of HDV.

Rac GTPase activity is essential for EGF-induced mitogenesis

Rac, a member of the Rho family GTPases, has been implicated in the regulation of a wide range of biological processes including actin remodeling, cell transformation, G1 cell cycle progression, and gene expression. To determine whether Rac GTPase activity is required for epidermal growth factor-induced mitogenesis, Rat-2 stable cells expressing a dominant-negative Rac1 mutant, RacN17, were prepared. Exposure to EGF exhibited a significantly restricted growth response in Rat-2-RacN17 cells compared to Rat-2 parental cells, suggesting an essential role of Rac in EGF-induced mitogenesis. In contrast, addition of lysophosphatidic acid exerted the same level of growth in Rat-2 and Rat-2-RacN17 cells. To gain further evidence for the essential role of Rac in EGF-induced mitogenesis, we performed the microinjection experiment. EGF-induced DNA synthesis was significantly blocked by microinjection of recombinant RacN17 protein, and not control IgG. Our further study to analyze the downstream mediator of Rac in EGF-signaling to mitogenesis demonstrated that Rac-activated phospholipase A2 plays a critical role. Taken together, our results suggest that the "Rac and Rac-activated PLA2" cascade is one of the major mitogenic pathways induced by EGF.

Hepatitis C virus core protein interacts with the cytoplasmic tail of lymphotoxin-beta receptor

Hepatitis C virus (HCV) core protein is a multifunctional protein. We examined whether it can interact with cellular proteins, thus contributing to viral pathogenesis. Using the HCV core protein as a bait to screen a human liver cDNA library in a yeast two-hybrid screening system, we have isolated several positive clones encoding cellular proteins that interact with the HCV core protein. Interestingly, more than half of these clones encode the cytoplasmic domain of lymphotoxin-beta receptor (LT betaR), which is a member of the tumor necrosis factor receptor family. Their binding was confirmed by in vitro glutathione S-transferase fusion protein binding assay and protein-protein blotting assay to be direct and specific. The binding sites were mapped within a 58-amino-acid region of the cytoplasmic tail of LT betaR. The binding site in the HCV core protein was localized within amino acid residues 36 to 91 from the N terminus, corresponding to the hydrophilic region of the protein. In mammalian cells, the core protein was found to be associated with the membrane-bound LT betaR. Since the LT betaR is involved in germinal center formation and developmental regulation of peripheral lymphoid organs, lymph node development, and apoptotic signaling, the binding of HCV core protein to LT betaR suggests the possibility that this viral protein has an immunomodulating function and may explain the mechanism of viral persistence and pathogenesis of HCV.

Hepatitis C virus NS5B protein is a membrane-associated phosphoprotein with a predominantly perinuclear localization

Hepatitis C virus NS5B protein is an RNA-dependent RNA polymerase. To investigate the properties and function of this protein, we have expressed the NS5B protein in insect and mammalian cells. NS5B was found to be present as fine speckles in the cytoplasm, particularly concentrated in the perinuclear region, suggesting its association with the nuclear membrane, the endoplasmic reticulum, or the Golgi complex. This conclusion was supported by the biochemical demonstration that NS5B was associated with the membranes in the cells. Furthermore, it was shown that NS5B protein is a phosphoprotein. These properties may be related to its function as an RNA polymerase.

Homotypic interaction and multimerization of hepatitis C virus core protein

Hepatitis C virus (HCV) core protein constitutes a viral nucleocapsid and may possess multiple functions. In this study, we demonstrated the homotypic interaction and multimerization of HCV core protein in vitro and in vivo. By using a yeast two-hybrid system, we showed that the amino-terminal hydrophilic portion (amino acids 1-115) of the core protein could interact with itself. Deletion analysis mapped the interacting domain within amino acid residues 36-91. The homotypic interaction of the core protein was also confirmed by in vitro protein-protein blotting assay using the recombinant HCV core proteins and by its binding to the glutathione S-transferase core fusion protein. The biological significance of the core protein self-interactions was demonstrated by the detection of multimeric forms of the core protein in mammalian cells. The domain responsible for multimerization was determined to be within the amino-terminal hydrophilic region (amino acids 1-115). Both the membrane-bound and the free core proteins exist in dimeric and multimeric forms, suggesting that multimerization of the HCV core protein occurred at an early stage of viral assembly and that the multimer forms may be involved in multiple functions of the core protein.

A pregnancy-specific glycoprotein is expressed in the brain and serves as a receptor for mouse hepatitis virus

Mouse hepatitis virus (MHV), a murine coronavirus known to cause encephalitis and demyelination, uses murine homologues of carcinoembryonic antigens as receptors. However, the expression of these receptors is extremely low in the brain. By low-stringency screening of a mouse brain cDNA library, we have identified a member of the pregnancy-specific glycoprotein (PSG) subgroup of the carcinoembryonic antigen gene family. Unlike other PSG that are expressed in the placenta, it is expressed predominantly in the brain. Transfection of the cDNA into COS-7 cells, which lack a functional MHV receptor, conferred susceptibility to infection by some MHV strains, including A59, MHV-2, and MHV-3, but not JHM. Thus, this is a virus strain-specific receptor. The detection of multiple receptors for MHV suggests the flexibility of this virus in receptor utilization. The identification of this virus in receptor utilization. The identification of a PSG predominantly expressed in the brain also expands the potential functions of these molecules.

Differential subcellular localization of hepatitis C virus core gene products

The expression of the core gene of two different hepatitis C virus (HCV) isolates was analyzed. In the presence of its downstream E1 envelope protein sequence, two major core protein products with molecular masses of 21 kDa (P21) and 19 kDa (P19) and a minor protein product with molecular mass of 16 kDa (P16) were detected. In the absence of its downstream E1 envelope protein sequence, P21 and P19 remained the major protein products expressed from the core gene of the HCV-RH isolate, whereas P16 became the major protein product of the core gene of the HCV-1 isolate. Analysis of the amino-terminal sequences of P21 and P16 expressed in Escherichia coli revealed that P21 and P16 were co-amino terminal. Deletion-mapping analysis indicated that P16 lacked the carboxy-terminal sequence of P21. Immunofluorescence analysis of the subcellular localization of different HCV core proteins indicated that P21 and P19 displayed a reticular and punctate staining pattern typical of endoplasmic reticulum-associated proteins, while P16 was localized to the nucleus. The distinct subcellular localization of P16 raises the possibility that P16 may have a biological function very different from those of P21 and P19.

Isoprenylation masks a conformational epitope and enhances trans-dominant inhibitory function of the large hepatitis delta antigen

Hepatitis delta antigen (HDAg) consists of two species, large (LHDAg) and small (SHDAg), which are identical in sequence except that the large form contains 19 extra amino acids at the C terminus. The large form is prenylated on the Cxxx motif. The small form can trans activate HDV RNA replication, while the large form inhibits it. To determine the molecular basis for their differential functions, we examined the effects of prenylation on the conformation and function of HDAg. We show that the presence of prenylates masks a conformational epitope which is present in SHDAg but hidden in wild-type LHDAg; this epitope becomes exposed in all of the nonprenylated mutant LHDAgs. Prenylation also plays a major role in conferring the trans-dominant negative inhibitory activity of LHDAg, since the loss of prenylation in LHDAg reduced its inhibitory activity. The primary amino acids of the C-terminal sequence also contributed to the maintenance of the HDAg protein conformation; a prenylated LHDAg mutant with a five-amino-acid deletion had an exposed C-terminal epitope. By examining LHDAg mutants which have deletions of various extents of C-terminal sequence, with or without the prenylation motif, we have further shown that all of the prenylated mutants have much higher levels of trans-dominant suppressor activities than do the corresponding nonprenylated mutants. Surprisingly, a few nonprenylated LHDAg mutants were able to trans activate HDV RNA replication, while all of the prenylated ones lost this function. These results suggest that isoprenylates cause the masking of a conformational epitope of HDAg and that conformational differences between the large and small HDAgs account for the differences in their trans-activating and trans-dominant inhibitory biological activities.

Isoprenylation mediates direct protein-protein interactions between hepatitis large delta antigen and hepatitis B virus surface antigen

Hepatitis delta antigen (HDAg) consists of two protein species of 195 and 214 amino acids, respectively, which are identical in sequence except that the large HDAg has additional 19 amino acids at its C terminus and is prenylated. Previous studies have shown that the large HDAg and the surface antigen of hepatitis B virus (HBsAg) together can form empty hepatitis delta virus (HDV) particles. To understand the molecular mechanism of HDV virion morphogenesis, we investigated the possible direct protein-protein interaction between HDAg and HBsAg. We constructed recombinant baculoviruses expressing the major form of HBsAg and various mutant HDAgs and used these proteins for far-Western protein binding assays. We demonstrated that HBsAg interacted specifically with the large HDAg but not with the small HDAg. Using mutant HDAgs which have defective or aberrant prenylation, we showed that this interaction required isoprenylates on the cysteine residue of the C terminus of the large HDAg. Isoprenylation alone, without the remainder of the C-terminal amino acids of the large HDAg, was insufficient to mediate interaction with HBsAg. This study demonstrates a novel role of prenylates in HDV virion assembly.

MK 287: a potent, specific, and orally active receptor antagonist of platelet-activating factor

MK 287 (L-680,573), a tetrahydrofuran analog, potently inhibited [3H]C18-PAF binding to human platelet, polymorphonuclear leukocyte (PMN) and lung membranes with K1 values of 6.1 +/- 1.5, 3.2 +/- 0.7, and 5.49 +/- 2.3 nM, respectively. The inhibitory effects are stereospecific and competitive. The racemate, L-668,750 is less potent and the enantiomer, L-680,574 is 20-fold less potent than MK 287. Inhibition of the binding of [3H]C18-PAF to human PMN membranes by MK 287 was associated with the reduction of the affinity of the radioligand but not the number of the receptor sites. Binding of other radioligands (e.g., LTB4, LTC4, C5a, FMLP) to their specific receptors was unaltered at 1-10 microM MK 287. [3H]MK 287 bound to membranes from human platelets and PMNs: KD = 2.1 +/- 0.6 and 2.9 +/- 1.2 nM, respectively. When examined on isolated human cells, MK 287 potently and selectively inhibited PAF-induced aggregation of platelets in plasma (ED50 = 56 +/- 38 nM) or gel-filtered platelets (ED50 = 1.5 +/- 0.5 nM) and elastase release from PMNs (ED50 = 4.4 +/- 2.6 nM). In studies in vivo, MK 287 inhibited PAF-induced lethality in mice (ED50 = 0.8 mg/kg orally) and PAF-induced bronchoconstriction in guinea pigs (ED50 = 0.18 mg/kg intraduodenally and 0.19 mg/kg intravenously). Inhibition of PAF-induced bronchoconstriction was accompanied by parallel rightward shifts in concentration-response curves for PAF-induced platelet aggregation measured ex vivo.

A unique conformation at the carboxyl terminus of the small hepatitis delta antigen revealed by a specific monoclonal antibody

Two forms of the hepatitis delta antigen (HDAg), a small (24 kDa) and a large (27 kDa) one, have different functions in the hepatitis delta virus (HDV) replication cycle. The small HDAg trans-activates RNA replication, while the large one inhibits RNA replication. The lack of the trans-acting activity in the large HDAg, even though it contains the complete sequence of small HDAg, suggests that the large HDAg lacks a certain functional conformation. To test such a possibility, monoclonal antibodies (MAbs) were generated from mice immunized with recombinant baculovirus-expressed small HDAg. As expected, most of the MAbs recognized both small and large HDAg. In addition, one MAb (9E4) was obtained which recognized only the small HDAg, but not the large one, in Western blot and immunoprecipitation analysis, suggesting that it recognized an epitope unique to small HDAg. However, MAb 9E4 detected both forms of HDAg in virus-infected cells by immunofluorescence and reacted with TrpE-large HDAg fusion proteins expressed in Escherichia coli, suggesting that this MAb recognizes a conformation-dependent epitope which is not present in the native large HDAg molecule but is detectable in LHDAg when its conformation is altered. The 9E4 epitope was mapped within a region of 32 amino acids at the carboxyl-terminus of small HDAg, indicating that this region contains a unique conformation not present in the native molecule of large HDAg. Since this is the only structure identified that is unique to small HDAg, the C-terminal region may contain the domain associated with the biological activities unique to the small HDAg.

Hepatitis delta antigen expressed by recombinant baculoviruses: comparison of biochemical properties and post-translational modifications between the large and small forms

Hepatitis delta virus (HDV) encodes only one protein, the hepatitis delta antigen (HDAg). Two forms of HDAg, a large (27 kDa) and a small (24 kDa) one, participate in the various steps of HDV replication. To further understand the properties of HDAg, we have constructed recombinant baculoviruses and expressed both forms of the HDAg in insect cells. The gene encoding HDAg was placed under the control of the polyhedrin promoter of Autographa Californica nuclear polyhedrosis virus (AcNPV) by homologous recombination. When Spodoptera frugiperda (Sf9) cells were infected with the recombinant viruses, both the small HDAg and the large HDAg were expressed at high levels. The HDAgs produced by the recombinants were similar in size and antigenic properties to those of the proteins produced in mammalian hepatoma cell lines. It was also localized exclusively in the nuclei. In addition, both proteins bound to HDV RNA in an in vitro assay. No difference in the RNA-binding affinity was noted between the two forms of HDAg, suggesting that the trans-dominant inhibitory activity of the large HDAg on HDV replication is not due to its competition with the small HDAg for RNA binding. Two RNA-protein complexes could be detected, suggesting either that there are at least two binding sites on the HDV RNA or that HDAg binds to HDV RNA in two multimeric forms. We have further shown that both the large and the small HDAgs are phosphoproteins, with the former having an approximately sixfold higher level of phosphorylation. Finally, it was demonstrated that the large HDAg was isoprenylated, while the small one was not. These differences in post-translational modifications are the first differences in biochemical properties demonstrated between the two forms and may explain the differential effects of the large and small HDAgs on HDV RNA replication and virus packaging.

L-659,989: a useful probe in the detection of multiple conformational states of PAF receptors

L-659,989 is a potent, specific and competitive platelet-activating factor (PAF) receptor antagonist. The 2,5-tritium labeled L-659,989, similar to [3H]PAF, specifically binds to rabbit platelet membranes with an equilibrium dissociation constant (KD) of 1.60 (+/- 0.20) nM in 10 mM MgCl2. However, guanosine 5'-triphosphate (GTP) and several cations affect the specific binding of [3H]PAF and of [3H]L-659,989 to rabbit platelet membranes in different ways. K+, Mg2+, Ca2+ and Mn2+ potentiate the specific binding of both ligands. Na+ and Li+ inhibit the specific [3H]PAF binding, but enhance the binding of [3H]L-659,989; GTP reduces the [3H]PAF binding but has no effect on the binding of [3H]-L-659,989. Ni2+ inhibits the [3H]L-659-989 binding, but has no effect on the binding of [3H]PAF. In the presence of 150 mM NaCl, [3H]L-659,989 exhibits identical KD and detectable binding sites (Bmax) values as those in the presence of 10 mM MgCl2, while KD And Bmax values of [3H]PAF are dramatically reduced in the presence of 150 mM NaCl compared to those in 10 mM MgCl2. These results suggest the existence of multiple conformational states of the PAF specific receptor and that PAF and L-659,989 bind differently to those states. In the presence of 150 mM NaCl and 1 mM GTP, receptors appear to exist in a single conformational state with an equilibrium dissociation constant (KB) of 0.93 microM for PAF as derived from the Schild plot. In isolated rabbit platelets pretreated with 10 microM ETH 227, a Na(+)-specific ionophore, the detectable [3H]PAF binding sites drop from 260 to 100 binding sites per platelet, but the binding sites for [3H]L-659,989 remain roughly the same. The Na+ binding sites which modulate the conformation of PAF receptors are therefore protected from extracellular Na+ until ionophore is added, and are probably located on the cytoplasmic side of the plasma membrane.

Wheat germ agglutinin potentiates specific binding of platelet-activating factor to human platelet membranes and induces platelet-activating factor synthesis in intact platelets

Specific binding of tritium-labeled platelet-activating factor (PAF) and a nonmetabolizable bioactive analog of PAF, 1-O-alkyl-2-N-methylcarbamyl-sn-glyceryl-3-phosphorylcholine, to human platelet membranes was found to be potentiated by wheat germ agglutinin (WGA) and erythroagglutinin. As demonstrated in Scatchard plots, the potentiation effect is due to an increase in the maximal number of receptor sites, with no alteration in the equilibrium dissociation constant. The WGA-potentiated specific binding can be specifically inhibited by N-acetylglucosamine, shows identical affinity for PAF agonists and a receptor antagonist, L-659,989, and has an identical Na+ inhibition pattern to non-treated membranes in the absence of WGA. The WGA-induced potentiation is preferential in the plasma membrane-enriched fraction. The maximal number of receptor sites increases in membranes pretreated with neuraminidase and beta-N-acetylglucosaminidase. Therefore, WGA may bind to an endogenous PAF receptor modulator, which then either dissociates from or associates with the PAF receptor and regulates the receptor conformation. The membrane fraction enriched with intracellular membranes is also enriched with PAF receptors. WGA was also found to increase the maximal aggregation of rabbit and human platelets induced by PAF and to induce the synthesis of PAF, which preceded aggregation in human platelets. An intracellular PAF receptor may also exist, and it could modulate the function of PAF retained inside of the stimulated cells.

Specific binding of tritium-labeled inositol 1,4,5-trisphosphate to human platelet membranes: ionic and GTP regulation

Specific, saturable and reversible binding of tritium-labeled inositol 1,4,5-trisphosphate [( 3H]Ins(1,4,5)P3) to human platelet membranes is demonstrated. The Ins(1,4,5)P3-binding sites are abundant and display high selectivity for Ins(1,4,5)P3. Other inositol phosphates exhibit much lower affinity for this site. The specific [3H]Ins(1,4,5)P3 binding was found to be modulated by pH, monovalent and divalent cations, and GTP. A sharp increase in binding occurs at slightly alkaline pH. The monovalent cations, Na+, K+ and Li+ almost double the binding at 30 mM. Mg2+ inhibits the specific [3H]Ins(1,4,5)P3 binding. At low concentrations of Ca2+, the binding is inhibited, but at concentrations higher than 5 mM the binding is potentiated and increases by almost 5-fold at 100 mM. Similar pattern of the effects is also observed for Mn2+ and Sr2+. The specific [3H]Ins(1,4,5)P3 binding is specifically inhibited by GTP. Other nucleotides also inhibit the binding but at higher concentrations. From saturation binding studies, Ca2+ potentiation seems to be due to the conversion of the receptor from the low-affinity state to the high-affinity one. In the absence of Ca2+, the Scatchard plot is nonlinear and concave, and statistically can be fitted best with two equilibrium dissociation constants (Kd values), 0.19 +/- 0.11 and 13.2 +/- 18.1 nM, respectively, for high- and low-affinity binding sites. However, in the presence of 100 mM CaCl2, the Scatchard plot reveals only the high-affinity binding sites with a Kd value of 0.32 +/- 0.15 nM. The specific Ins(1,4,5)P3 receptor in human platelets could therefore exist in multiple conformational states to regulate the intracellular Ca2+ concentration.

High affinity receptor binding of platelet-activating factor in rat peritoneal polymorphonuclear leukocytes

Rat peritoneal polymorphonuclear leukocytes (PMNs) showed a single class of high affinity binding sites for platelet-activating factor (PAF) with an equilibrium dissociation constant (KD) of 4.74 (+/- 2.59) nM. Each cell contained 2.79 (+/- 1.40) x 10(4) receptors. In the isolated membranes at pH 7.0 in 10 mM MgCl2, 10 mM Tris and 0.25% bovine serum albumin, the KD value was 0.61 (+/- 0.1) nM, which is roughly identical to the KD values reported previously for various membrane systems under identical ionic conditions. The receptors were highly specific for PAF. Several receptor antagonists that are reported to inhibit the binding of [3H]PAF and the PAF-induced function in platelets could fully displace the binding. The biologically inactive enantiomer (enantio-C16-PAF), a PAF analog, azido-PAF, and an indene derivative of the PAF receptor antagonist, L-651,142, had different potencies to inhibit [3H]PAF binding to rat and human PMN membranes. L-652,731, a tetrahydrofuran analog of the PAF receptor antagonist was about 10 times more potent to inhibit the binding in rat liver tissues than in rat PMNs. These results suggest that PAF receptors on human and rat PMNs are not identical and that PAF receptor subtypes may exist in rat liver and PMNs.

Prolongation of parturition in the pregnant rat following treatment with a platelet activating factor receptor antagonist

The presence of platelet activating factor (PAF) in amniotic fluid of women only in labor is indicative of a role for PAF in parturition. In addition, stimulated amnion membrane produces both PAF and prostaglandin E2, each of which is capable of inducing myometrial contraction. To evaluate the involvement of PAF in the process of parturition, we administered the PAF receptor antagonist, L-659,989, to 17-day timed pregnant rats and followed the events of labor and delivery. Administration by mouth with L-659,989 of three concentrations (1.6, 16, and 48 mg/kg/day) did not alter the gestational period; however, the duration of parturition was increased from 2-fold to 5-fold by such treatment. No toxicity of the analog was apparent; treated dams showed no signs of morbidity, and fetal mortality was not significantly altered by treatment with the antagonist. Based on these experiments, it is suggested that the PAF receptor antagonist interferes with the normal progression of events of parturition and that PAF is an integral mediator in initiating the myometrial contraction necessary for expulsion of the fetus.

Competitive inhibition of tritium-labeled platelet-activating factor binding to rabbit platelet membranes by amiloride and amiloride analogs

Amiloride and its structural analogs, ethylisopropyl amiloride, benzamil, and dichlorobenzamil, inhibit both the specific [3H]C18-PAF binding to rabbit platelet membranes and PAF-induced aggregation of gel-filtered rabbit platelets. Detailed analysis of binding inhibitions demonstrate that ethylisopropyl amiloride is a competitive inhibitor with an equilibrium dissociation constant (KB) of 23 microM. The concentration of amiloride and its analogs needed to inhibit the PAF-induced aggregation is high and there exists no correlation between their inhibitory activities of platelet aggregation and those of Na+/H+ antiporter. However, the inhibitory effects on the PAF-induced aggregation are parallel to those on the specific [3H]C18-PAF binding. The inhibitory effects of amiloride and its analogs on the activation of platelets are at the PAF-receptor binding step, rather than at the Na+/H+ antiporter.

Characterization of platelet-activating factor (PAF) receptor by specific binding of [3H]L-659,989, a PAF receptor antagonist, to rabbit platelet membranes: possible multiple conformational states of a single type of PAF receptors

(trans)-2-(3-Methoxy-5-methylsulfonyl-4-propoxyphenyl)-5-(3,4,5- trimethoxyphenyl)tetrahydrofuran (L-659,989) is a potent and orally active platelet-activating factor (PAF)-specific and competitive receptor antagonist. The 2,5-tritium-labeled L-659,989 ([3H]L-659,989) specifically binds to rabbit platelet membranes with an equilibrium dissociation constant (KD) of 1.60 +/- 0.20 nM in 10 mM MgCl2. Several selected PAF analogs and PAF receptor antagonists show equilibrium inhibition constants roughly similar to those found in the specific [3H]PAF binding assay. Other pharmacological agents with no PAF antagonistic activities do not inhibit the specific binding of [3H]L-659,989. K+ and divalent cations such as Mg2+, Ca2+, and Mn2+ potentiate the specific [3H]L-659,989 binding. Na+ and Li+ also enhance but GTP shows no effect on the specific binding of [3H]L-659,989. However, Ni2+ inhibits the specific binding. Scatchard analysis demonstrates that the potentiating effect of these cations is due to an increase in the detectable receptor number for L-659,989. In 10 mM MgCl2 [3H]L-659,989 shows higher receptor number than [3H]PAF. Under various ionic conditions with or without GTP, in which [3H] L-659,989 binding remains approximately the same, C16-PAF shows different potencies in competing against the specific [3H] L-659,989 binding. These results demonstrate the existence of multiple conformational states of the PAF-specific receptor. The variation in the detectable receptor number under different conditions is due to the coexistence of the high and low affinity states and the fact that the low affinity state(s) of the receptor with KD value(s) possibly in the micromolar range cannot be detected in the Scatchard analysis with the radioligand at nanomolar concentrations. In the presence of 150 mM NaCl and 1 mM GTP, receptors exist in a single conformational state with an equilibrium dissociation constant (KB) of 0.931 microM for PAF.

Biochemical and pharmacological characterization of L-659,989: an extremely potent, selective and competitive receptor antagonist of platelet-activating factor

L-659,989 [trans-2-(3-methoxy-5-methylsulfonyl-4-propoxy-phenyl)-5-(3,4,5- trimethoxyphenyl)tetrahydrofuran] is a p.o. active and extremely potent, selective and competitive platelet-activating factor (PAF) receptor antagonist. It inhibited [3H]PAF binding to either rabbit platelet or rabbit polymorphonuclear leukocyte membranes with an equilibrium inhibition constant (Kl) of 1.1 nM; whereas in human platelet, human polymorphonuclear leukocyte or human lung membranes, L-659,989 was about 10 times less potent with a Kl of 14.3 nM. The structural specificity of L-659,989 was demonstrated by the low activity of its cisisomer which was about 100 to 200 times less potent, also the (-)-L-659,989 was found to be 20- to 30-fold more potent than (+)-L-659,989. In both [3H]PAF binding and PAF-induced platelet aggregation inhibition, L-659,989 was found to be a competitive inhibitor with an equilibrium dissociation constant (KB) of 1.5 and 1.7 nM, respectively, in rabbit platelets. Even up to 6 microM concentration, L-659,989 showed no inhibition on the aggregation of rabbit platelets in plasma induced by ADP, arachidonic acid, collagen or thrombin. In an in vivo model, it inhibited guinea pig bronchoconstriction induced by i.v. infusion of 75 ng/kg of PAF with ED50 values of 13 micrograms/kg i.v. and 0.5 mg/kg p.o.

Identification of a second putative receptor of platelet-activating factor from human polymorphonuclear leukocytes

Due to multiple molecular species of platelet-activating factor (PAF) and the existence of high affinity binding sites in a variety of cells and tissues, possible existence of PAF receptor subtypes has been suggested. This report shows differences between specific PAF receptors in human leukocytes and platelets. Human polymorphonuclear leukocyte membranes showed high affinity binding sites for PAF with an equilibrium dissociation constant (KD) of 4.4 (+/- 0.3) x 10(-10) M. We compared the relative potencies of several PAF agonists and receptor antagonists between human platelet and human leukocyte membranes. One receptor antagonist (Ono-6240) was found to be 6-10 times less potent in inhibiting the specific [3H]PAF receptor binding, PAF-induced GTPase activity, as well as the PAF-induced aggregation in human leukocytes than in human platelets. Mg2+, Ca2+, and K+ ions potentiated the specific [3H]PAF binding in both systems. Na+ and Li+ ions inhibited the specific [3H]PAF binding to human platelets but showed no effects in human leukocytes. K+ ions decreased the Mg2+-potentiated [3H]PAF binding in human leukocytes but showed no effects in human platelets. PAF stimulates the hydrolysis of [gamma-32P] GTP with an ED50 of about 1 nM, whereas the biological inactive enantiomer shows no activity even at 10 microM in both human platelets and human leukocytes. The PAF-stimulated GTPase in human leukocytes can be abolished by the pretreatment of membranes with pertussis toxin and cholera toxin. However, the PAF-stimulated activity of GTPase in human platelets is insensitive to pertussis toxin and cholera toxin. These results suggest that there exists a second type of PAF receptor in human polymorphonuclear leukocytes, which is structurally different from the one characterized in human platelets, and that the guanine nucleotide-binding protein coupled to PAF receptors in human leukocytes is also different from the one in human platelets.

(+/-)-trans-2-(3-Methoxy-5-methylsulfonyl-4-propoxyphenyl)-5-(3,4,5- trimethoxyphenyl)tetrahydrofuran (L-659,989), a novel, potent PAF receptor antagonist

The title compound, L-659,989, is a highly potent, competitive, and selective antagonist of the binding of [3H]PAF to its receptors in platelet membranes from rabbits and humans. It exhibits equilibrium inhibition constants for PAF binding of 1.1 nM (rabbit) to 9.0 nM (human), values that are at least 1-2 orders of magnitude lower than those of other PAF antagonists tested. L-659,989 potently inhibits PAF-induced aggregation of rabbit platelets and degranulation of rat (ED50 4.5 nM) and human (ED50 10 nM) neutrophils. L-659,989 inhibits PAF-induced extravasation and lysosomal enzyme release in rats, and is active orally in female rats (ED50 0.2 mg/kg) with an extraordinary oral duration of action of 12 to 16 hours at 1.0 mg/kg p.o.