Impact of tuberculosis on the incidence of osteoporosis and osteoporotic fractures: a nationwide population-based cohort study.

OBJECTIVES: Despite the high prevalence of tuberculosis (TB) and the disease burden of osteoporosis and osteoporotic fractures, there is still a lack of well-designed, large-scale studies demonstrating associations among them. We aimed to investigate the effect of TB on the incidence of osteoporosis and osteoporotic fractures. STUDY DESIGN: This was a nationwide population-based cohort study. METHODS: This study was conducted using the National Health Insurance Service Database of South Korea. We included patients with newly diagnosed TB aged >40 years from January 2006 to December 2017. An uninfected control for each TB patient was randomly extracted by frequency matching for sex, age, income level, residence, and registration date at a 2:1 ratio. The primary outcome was the incidence of osteoporosis and osteoporotic fractures between the two groups, adjusted for sex, age, income level, residence, comorbidities, body mass index, blood pressure, laboratory tests, alcohol drinking, and smoking. The risk factors associated with osteoporosis or osteoporotic fractures were also investigated. RESULTS: A total of 164,389 patients with TB and 328,778 matched controls were included (71.9% males). The mean duration of follow-up was 7.00 ± 3.49 years. The incidence of osteoporosis in patients with TB was 6.1 cases per 1000 person-years, which was significantly higher than that in matched controls (adjusted hazard ratio [aHR] 1.349, 95% confidence interval [CI] 1.302-1.398, P < 0.001). The incidence of osteoporotic fractures was also higher in patients with TB than in controls (aHR 1.392, 95% CI 1.357-1.428, P < 0.001). Among fractures, the risk of hip fracture was the highest (aHR 1.703, 95% CI 1.612-1.798, P < 0.001). CONCLUSIONS: TB independently contributes to the incidence of osteoporosis and osteoporotic fractures, particularly hip fractures.

Clinical and Immunological Characterization of Perilla Seed Allergy in Children.

BACKGROUND AND OBJECTIVES: Perilla seeds are known to cause immediate allergic reactions. However, reports on perilla seed allergy are limited to a few case reports worldwide, and there is currently no diagnostic test for this allergy. Our objective was to analyze the clinical and immunological characteristics of perilla seed allergy and to identify allergens for the development of diagnostic methods. METHODS: Twenty-one children with clinical perilla seed allergy were enrolled from 2 tertiary hospitals between September 2016 and June 2019. Using perilla seed extract, we developed a skin prick test (SPT) and an IgE enzyme-linked immunosorbent assay (ELISA) for diagnosis of perilla seed allergy. IgE immunoblotting was performed to identify putative allergenic components, and amino acid composition analysis was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). RESULTS: The median age of children with perilla seed allergy was 3 years; the proportion of children with anaphylaxis was 28.6%. SPT was performed with perilla seed in 15 of 21 children, all of whom tested positive. On ELISA, 85.7% of children tested positive for perilla seed-specific IgE. Proteins with molecular weights of 50, 31-35, and 14-16 kDa bound to the sera of >50% of children with perilla seed allergy. LC-MS/MS analysis of these 3 protein fractions showed 8 putative proteins, including perilla oleosin (Accession No. 9963891), to be allergens. CONCLUSIONS: This study documented the clinical characteristics and immunological profiles of 21 children with perilla seed allergy. Our results suggest that oleosin is one of the major allergens in perilla seeds.

Clinical and Immunological Characterization of Perilla Seed Allergy in Children

Background: Perilla seeds are known to cause immediate allergic reactions. However, reports on perilla seed allergy are limited to a few case reports worldwide, and there is currently no diagnostic test for this allergy. Objective: Our objective was to analyze the clinical and immunological characteristics of perilla seed allergy and to identify allergens for the development of diagnostic methods. Methods: Twenty-one children with clinical perilla seed allergy were enrolled from 2 tertiary hospitals between September 2016 and June 2019. Using perilla seed extract, we developed a skin prick test (SPT) and an IgE enzyme-linked immunosorbent assay (ELISA) for diagnosis of perilla seed allergy. IgE immunoblotting was performed to identify putative allergenic components, and amino acid composition analysis was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results: The median age of children with perilla seed allergy was 3 years; the proportion of children with anaphylaxis was 28.6%. SPT was performed with perilla seed in 15 of 21 children, all of whom tested positive. On ELISA, 85.7% of children tested positive for perilla seed-specific IgE. Proteins with molecular weights of 50, 31-35, and 14-16 kDa bound to the sera of >50% of children with perilla seed allergy. LC-MS/MS analysis of these 3 protein fractions showed 8 putative proteins, including perilla oleosin (Accession No. 9963891), to be allergens. Conclusion: This study documented the clinical characteristics and immunological profiles of 21 children with perilla seed allergy. Our results suggest that oleosin is one of the major allergens in perilla seeds (AU)

Antecedentes: Las semillas de perilla pueden causar reacciones alérgicas inmediatas. Sin embargo, existen escasos estudios, limitados a escasos casos clínicos, sin que existan pruebas diagnósticas para esta alergia alimentaria.Objetivo: El objetivo de este trabajo es analizar las características clínicas e inmunológicas de los pacientes con alergia a semillas de perilla e identificar los alérgenos responsables con el fin de desarrollar nuevos métodos diagnósticos. Métodos: Se reclutaron 21 niños con alergia a semillas de perilla procedentes de dos hospitales entre septiembre de 2016 y 2019. Se realizaron prick test y determinación de IgE específica in vitro mediante ELISA utilizando un extracto de perilla. Igualmente se realizó immunoblotting para identificar los componentes alergénicos y determinar su composición mediante cromatografía líquida y espectometría de masas (LC-MS/MS). Resultados: Los niños con alergia a perilla tienen una mediana de edad de 3 años. El 28,6% de estos niños presentaron anafilaxia. Se realizó prick test con el extracto de perilla en 15/21 niños con resultado positivo en todos ellos. La IgE específica in vitro mediante ELISA fue positiva en el 85,7% de los casos. Más del 50% de los niños reconocían proteínas de 50, 31–35 y 14–16 kDa. El análisis mediante LC-MS/MS de estas tres fracciones identificó 8 proteínas diferentes, incluyendo una oleosina (Accession No. 9963891), como posibles alérgenos. Conclusiones: Este trabajo describe las características clínicas e inmunológicas de 21 niños con alergia a semillas de perilla. Nuestros resultados sugieren que una oleosina es uno de los alérgenos mayores en los pacientes con alergia a semillas de perilla (AU)

Do severe maternal morbidity and adequate prenatal care affect the delivery cost? A nationwide cohort study for 11 years with follow up.

OBJECTIVE: To explore whether severe maternal morbidity (SMM) and adequate prenatal care (PNC) affect delivery cost. DESIGN: Population-based retrospective cohort study. SETTING: National Health Insurance Service National Sample Cohort in Korea. POPULATION: A total of 90 035 deliveries in 2003 and 2013. METHODS: Severe maternal morbidity was determined using the Centers for Disease Control and Prevention's algorithm. Delivery medical costs were calculated by estimating claimed total medical costs using year-specific inflation adjustment factors. Adequate PNC was estimated by the Kessner Adequacy of Prenatal Care Index. To estimate adjusted mean delivery medical costs related to SMM, we applied a generalised estimating equation model with log link and γ distribution, by adjusting for all covariates. MAIN OUTCOME MEASURES: Delivery cost was calculated by estimating claimed total medical cost during delivery hospitalisation using year-specific inflation. RESULTS: Of the 90 035 deliveries, 2041 (2.27%) involved SMM. Women with SMM had a greater adjusted mean cost of delivery (US$ 1,263, 95% CI US$ 1,196-1,334) than those without (US$ 740, 95% CI US$ 729-750). Interestingly, women who had inadequate PNC had higher delivery medical costs than those with adequate PNC, adjusted for all covariates. CONCLUSION: Delivery involving SMM was associated with nearly doubled medical costs. Additionally, inadequate PNC increased the medical costs of delivery. The current study confirmed the burden of SMM and found that adequate PNC might be a useful preventive factor in reducing medical costs. TWEETABLE ABSTRACT: We found that women with severe maternal morbidity and inadequate prenatal care had increased medical costs during delivery hospitalisation.

Comparison of overall survival between antiviral-induced viral suppression and inactive phase chronic hepatitis B patients.

Nucleot(s)ide analogues (NAs) reduce the risk of hepatocellular carcinoma (HCC) in chronic hepatitis B (CHB) patients. However, the risk of HCC is reportedly higher for NA-treated patients than for patients in the inactive CHB phase. This study aimed to compare the long-term outcomes of CHB patients with NA-induced viral suppression and those of patients with inactive CHB. This retrospective study involved 1118 consecutive CHB patients whose HBV DNA level was continuously <2000 IU/mL during follow-up with/without antiviral agents. The patients were classified into inactive CHB (n = 373) or NA groups (n = 745). The primary endpoint was overall survival. Secondary endpoints included development of HCC and other liver-related events. The median duration of follow-up was 41.0 (interquartile range = 26.5-55.0) months. The difference in overall survival between the NA group vs. the inactive CHB group was not significant (hazard ratio [HR] = 0.78; 95% confidence interval [CI] = 0.33-1.85; P = .57). The NA group showed a significantly higher risk of HCC (HR = 3.44; 95% CI = 1.82-6.52; P < .01), but comparable risk for non-HCC liver-related events (HR = 1.02; 95% CI = 0.66-1.59; P = .93), compared with the inactive CHB group. Among patients with cirrhosis, the NA group showed a significantly lower risk of death (HR = 0.31; 95% CI = 0.097-0.998; P = .05) and non-HCC liver-related events (HR = 0.51; 95% CI = 0.31-0.83; P < .01), but a slightly higher risk of HCC (HR = 2.39; 95% CI = 0.85-6.75; P = .09), compared to the inactive CHB group. The overall survival of untreated patients with inactive CHB and of CHB patients achieving viral suppression with NA was comparable. However, NA treatment of cirrhotic patients was significantly associated with longer overall survival and lower risk of liver-related events.

Intensity of surveillance for hepatocellular carcinoma determines survival in patients at risk in a hepatitis B-endemic area.

BACKGROUND: Data are insufficient regarding the survival benefit of surveillance for hepatocellular carcinoma (HCC). AIM: To investigate the effectiveness of HCC surveillance in a hepatitis B-endemic population. METHODS: This retrospective cohort study included 1402 consecutive patients who were newly diagnosed with HCC between 2005 and 2012 at a single tertiary hospital in Korea. The primary endpoint was overall survival. Lead-time and length-time biases were adjusted (sojourn time = 140 days) and sensitivity analyses were performed. RESULTS: The most common aetiology was hepatitis B (80.4%). Cirrhosis was present in 78.2%. HCC was diagnosed during regular surveillance (defined as mean interval of ultrasonography <8 months, n = 834), irregular surveillance (n = 104) or nonsurveillance (n = 464). Patients in the regular surveillance group were diagnosed at earlier stages ([very] early stage, 64.4%) than the irregular surveillance (40.4%) or nonsurveillance (26.9%) groups and had more chance for curative treatments (52.4%) than the irregular surveillance (39.4%) or nonsurveillance (23.3%) groups (all P < 0.001). Mortality risk was significantly lower in the regular surveillance group (adjusted hazard ratio [aHR], 0.69; 95% [CI], 0.57-0.83) but not in the irregular surveillance group (aHR, 0.94; 95% CI, 0.69-1.28) compared with the nonsurveillance group after adjusting for confounding factors and lead-time. When the subjects were restricted to cirrhotic patients or Child-Pugh class A/B patients, similar results were obtained for mortality risk reduction between groups. CONCLUSIONS: HCC surveillance was associated with longer survival owing to earlier diagnosis and curative treatment. Survival advantage was significant with regular surveillance but not with irregular surveillance.

Entecavir and tenofovir reduce hepatitis B virus-related hepatocellular carcinoma recurrence more effectively than other antivirals.

Nucleos(t)ide analogues (NAs) have been shown to decrease the risk of hepatocellular carcinoma (HCC) recurrence. This study evaluated whether high-potency NAs (entecavir and tenofovir disoproxil fumarate [TDF]) reduce the risk of tumour recurrence more potently than low-potency NAs after curative treatment of hepatitis B virus (HBV)-related HCC. This study included 607 consecutive HBV-related HCC patients treated with surgical resection or radiofrequency ablation. The patients were categorized into three groups according to antiviral treatment: group A (no antiviral; n = 261), group B (low-potency NA; n = 90) and group C (high-potency NA; n = 256). The primary end-point was recurrence-free survival (RFS). During the duration of follow-up, the median RFS was 29.4, 25.1, and 88.2 months in groups A, B and C, respectively (P < .001, log-rank test). The multivariate Cox analysis indicated that group C had a significantly longer RFS than both group A (adjusted hazard ratio [HR] = 0.39, P < .001) and group B (adjusted HR = 0.47, P < .001). When baseline characteristics were balanced using inverse probability weighting, group C still had a significantly longer RFS than group A (adjusted HR = 0.46, P < .001) and group B (adjusted HR = 0.59, P = .007). Group C had significantly lower risk of viral breakthrough than group B (HR = 0.19, P < .001). Viral breakthrough was an independent risk factor for shorter RFS among groups B and C (adjusted HR = 2.03, P = .007, time-dependent Cox analysis). Antiviral agents with high genetic barrier to resistance (entecavir and TDF) reduced the risk of HCC recurrence compared with other antivirals and no antiviral treatment, especially in patients with high baseline viral load.

Delayed viral suppression during antiviral therapy is associated with increased hepatocellular carcinoma rates in HBeAg-positive high viral load chronic hepatitis B.

The treatment option in chronic hepatitis B (CHB) patients with persistent low-level viremia despite entecavir or tenofovir monotherapy is unclear. This study investigated the development of hepatocellular carcinoma (HCC) or cirrhosis in hepatitis B e antigen (HBeAg)-positive high viral load CHB patients, according to the time needed to achieve complete viral suppression. A total of 325 HBeAg-positive CHB patients with high viral load who were recently started on antiviral therapy with entecavir or tenofovir were included. The enrolled patients were divided into 2 groups with 4 separate criteria based on the time needed to achieve complete viral suppression: within 1, 2, 3 or 4 years of therapy initiation. The outcomes were development of HCC and cirrhosis. The cumulative incidence of HCC was significantly higher in patients failing complete viral suppression within 1 year (hazard ratio (HR), 4.54; 95% confidence interval (CI), 1.03-19.93; P = .045) or 2 years (HR, 3.38; 95% CI, 1.24-9.23; P = .018), than patients who achieved complete viral suppression within 1 or 2 years, respectively. Cumulative incidence of cirrhosis was also significantly higher in patients failing suppression within 1 year (HR, 1.95; 95% CI, 1.04-3.66; P = .037) or 2 years (HR, 2.44; 95% CI, 1.41-4.22; P = .001). When the time for achieving viral suppression exceeded 2 years, the cumulative incidence of HCC or cirrhosis was not different regardless of viral suppression. Complete hepatitis B virus suppression within 2 years of antiviral therapy initiation is associated with risk reduction in HCC or cirrhosis development.

Rifaximin treatment is associated with reduced risk of cirrhotic complications and prolonged overall survival in patients experiencing hepatic encephalopathy.

BACKGROUND: Rifaximin might decrease the risk of portal hypertension-related complications by controlling small intestinal bacterial overgrowth. AIM: To evaluate whether rifaximin was associated with the risk of death and cirrhotic complications. METHODS: We conducted a retrospective study that included 1042 patients experiencing hepatic encephalopathy (HE): 421 patients without hepatocellular carcinoma (HCC; the non-HCC cohort) and 621 patients with HCC (the HCC cohort). The primary endpoint was overall survival and secondary endpoints were recurrence of HE and the development of spontaneous bacterial peritonitis (SBP), hepatorenal syndrome (HRS) and variceal bleeding. RESULTS: In the non-HCC cohort, 145 patients received rifaximin plus lactulose (the rifaximin group) and 276 patients received lactulose alone (the control group). The multivariate analysis revealed that rifaximin was significantly associated with lower risk of death (adjusted hazard ratio [aHR], 0.697; P = .024) and reduced the risk of recurrent HE (aHR, 0.452; P < .001), SBP (aHR, 0.210; P < .001) and variceal bleeding (aHR, 0.425; P = .011) but not HRS (aHR, 0.598; P = .08). In the HCC cohort, 173 patients received rifaximin plus lactulose and 448 patients received lactulose. Rifaximin was not associated with the risk of death (aHR, 1.177; P = .121). Rifaximin was associated with lower risk of SBP (aHR, 0.323; P < .001) but not with variceal bleeding (aHR, 0.660; P = .104) or recurrent HE (aHR, 0.689; P = .057). The risk of Clostridium difficile-associated diarrhoea was not different between the groups (aHR, 0.028; P = .338). CONCLUSIONS: In patients without HCC, rifaximin treatment was significantly associated with prolonged overall survival and reduced risks of spontaneous bacterial peritonitis, variceal bleeding and recurrent hepatic encephalopathy.

A comparative study of perchlorate degradation in acute toxicity and chronic toxicity.

Since the discovery of perchlorate in water system, the public has been concerned about its human health effect. In practice it was reported that chronic exposure to perchlorate may lead to damage in thyroid hormone activity. This study introduced a method of perchlorate reduction, using autotrophic bacteria which utilise hydrogen as an electron donor. Two experiments were conducted to compare the effects of acute and chronic perchlorate toxicity on bacterial perchlorate reduction potential. One was a batch-fed operation generating acute toxicity and another was a continuous-fed operation generating chronic toxicity. Acclimation period of the batch-fed operation was 14 days while that of the continuous-fed operation was 31 days as commensurate with double. Lots of batch tests using the mixed culture passing through acclimation were conducted to figure out kinetics of biological perchlorate reduction. The maximum perchlorate utilisation rate (q(max)) of the mixed culture acclimated by acute toxicity was 2.92 mg ClO(4)(-)/mg dry-weight (DW)/d, while that of chronic toxicity was 0.27 mg ClO(4)(-)/mg DW/d. Half-maximum rate constants (K(s)) of acute and chronic toxicity were 567.3 and 25.6 mg ClO(4)(-)/L respectively. This result showed that acute toxicity acclimated the mixed culture more rapidly and produced a higher activity for biological perchlorate reduction than chronic toxicity.

The effect of rosiglitazone on insulin sensitivity and mid-thigh low-density muscle in patients with Type 2 diabetes.

AIMS: We examined the effect of rosiglitazone on insulin sensitivity, abdominal fat and mid-thigh intramuscular fat distribution, and plasma concentrations of adipocytokines in patients with Type 2 diabetes. METHODS: Rosiglitazone was administered at a daily dose of 4 mg to 42 Type 2 diabetes patients [age 32-70 years, body mass index (BMI) 17.5-32.6 kg/m(2), 15 women, 27 men] for 12 weeks. Various anthropometric and metabolic profiles, plasma adiponectin, leptin, and resistin levels were measured, and insulin resistance was calculated from the short insulin tolerance test. Body fat composition was assessed by computed tomography. RESULTS: Twelve weeks' rosiglitazone treatment resulted in improved insulin resistance despite increases in body weight and BMI. There was a significant decrease in abdominal visceral adipose tissue area (145 +/- 65.6 vs. 129 +/- 73.1 cm(2), P = 0.049). Mid-thigh low-density muscle area (TLDMA) increased from 23 +/- 9.6 to 26 +/- 8.2 cm(2) (P = 0.009). There were significant changes in plasma adipocytokines, but they were not significantly correlated with changes in insulin resistance. CONCLUSIONS: Rosiglitazone treatment resulted in an improvement of insulin responsiveness in Type 2 diabetic subjects, which was associated with the redistribution of visceral and subcutaneous adipose tissue, an increase in TLDMA, and changes in serum adipocytokine levels. Further studies are needed to elucidate the insulin sensitizing mechanism of rosiglitazone on peripheral skeletal muscles.

The effect of mosapride (5HT-4 receptor agonist) on insulin sensitivity and GLUT4 translocation.

AIMS: We investigated the effect of mosapride, 5HT-4 (5-hydroxytryptamine) agonist, on blood glucose level and insulin sensitivity in subjects with impaired glucose tolerance (IGT) and conducted an in vitro study to evaluate the action mechanism. METHODS: Thirty IGT patients were randomly assigned to receive either mosapride or placebo for 2 weeks. Biochemical profiles and insulin sensitivity index from euglycemic hyperinsulinemic clamp test were assessed before and after treatment. In cultured myotubes from human skeletal muscle cells, insulin- and mosapride-induced GLUT4 translocation and tyrosine phosphorylation of IRS-1 were determined. RESULTS: After 2 weeks of treatment with mosapride, glucose disposal rates were significantly increased up to those of control (mosapride 5.47+/-1.72 vs 7.06+/-2.13, P=0.004, placebo 5.42+/-1.85 vs 5.23+/-1.53mgkg(-1)min(-1)). Fasting plasma glucose (FPG) and insulin levels were decreased. Mosapride increased the contents of GLUT4 in plasma membrane representing the increased recruitment of glucose transporters from intracellular pool. While insulin treatment on human skeletal muscle cell resulted in an increased tyrosine phosphorylation of IRS-1, mosapride did not have any effect. CONCLUSIONS: Mosapride is effective in decreasing FPG without stimulating insulin secretion in IGT subjects, possibly by inducing GLUT4 translocation in skeletal muscles.

Divalproex extended-release in acute bipolar II depression.

BACKGROUND: Divalproex extended-release (divalproex-ER) is effective in acute mania, and limited data suggest divalproex may have efficacy in acute bipolar depression. METHODS: A 7-week, open-label trial of divalproex-ER monotherapy or adjunctive therapy was conducted in 28 outpatients (15 female, mean age 36.7+/-9.1, and mean duration of illness 22.1+/-11.1 years) with bipolar II depression (39% with rapid cycling course of illness within the prior year). Divalproex-ER was generally given as a single dose at bedtime, starting at 250mg and increased by 250mg every 4 days to symptom relief or adverse effects. Efficacy was assessed using weekly prospective Montgomery Asberg Depression Rating Scale (MADRS) scores. RESULTS: Overall, mean divalproex-ER final doses and serum concentrations were 1469mg/day and 80.1microg/mL, respectively. Mean MADRS scores (last observation carried forward) decreased significantly from baseline in patients in the overall group (from 30.1 to 15.2, p<.00001). The overall response rate was 54%. Divalproex-ER therapy was generally well tolerated, with no early discontinuations due to adverse events. LIMITATIONS: This study is limited by a small sample size and an open-label study design with no placebo control. CONCLUSIONS: Divalproex-ER as monotherapy and adjunctive therapy was well tolerated and yielded an overall response rate of 54% in bipolar II depression. Based on the results of this pilot study, randomized, double-blind, placebo-controlled studies of divalproex-ER in bipolar II depression are warranted.

Overlapping nuclei segmentation based on Bayesian networks and stepwise merging strategy.

This paper presents a new approach to the segmentation of fluorescence in situ hybridization images. First, to segment the cell nuclei from the background, a threshold is estimated using a Gaussian mixture model and maximizing the likelihood function of the grey values for the cell images. After the nuclei segmentation, the overlapping and isolated nuclei are classified to facilitate a more accurate nuclei analysis. To do this, the morphological features of the nuclei, such their compactness, smoothness and moments, are extracted from training data to generate three probability distribution functions that are then applied to a Bayesian network as evidence. Following the nuclei classification, the overlapping nuclei are segmented into isolated nuclei using an intensity gradient transform and watershed algorithm. A new stepwise merging strategy is also proposed to merge fragments into a major nucleus. Experimental results using fluorescence in situ hybridization images confirm that the proposed system produced better segmentation results when compared to previous methods, because of the nuclei classification before separating the overlapping nuclei.

8-O-Methylsclerotiorinamine, antagonist of the Grb2-SH2 domain, isolated from Penicillium multicolor.

A new secondary metabolite, 8-O-methylsclerotiorinamine (1), was isolated from a strain of Penicillium multicolor, and its structure was established using NMR spectroscopy and chemical evidence. The metabolite inhibited significantly the binding between the Grb2-SH2 domain and the phosphopeptide derived from the Shc protein and also blocked the protein-protein interactions of Grb2-Shc in cell-based experiments, with IC(50) values of 5.3 and 50 microM, respectively.

Natural and synthetic analogues of actinomycin D as Grb2-SH2 domain blockers.

Natural analogues (D, C2, and VII) of actinomycin inhibit Grb2 SH2 domain binding with phosphopeptide-derived from Shc in vitro and in intracellular system. To study structure-activity relationships, 13 actinomycin analogues were synthesized and we found that the inhibition activity depended on the substituents of cyclic peptide groups in actinomycin and two analogues with Tyr residue are the most potent inhibitors with IC50 value of 0.5 and 0.8 microM, respectively.

Actinomycin D as a novel SH2 domain ligand inhibits Shc/Grb2 interaction in B104-1-1 (neu*-transformed NIH3T3) and SAA (hEGFR-overexpressed NIH3T3) cells.

Actinomycins, a family of bicyclic chromopeptide lactones with strong antineoplastic activity, were screened as inhibitors of Shc/Grb2 interaction in in vitro assay systems. To investigate the effects of actinomycin D on Shc/Grb2 interaction in cell-based experiments, we used SAA (normal hEGFR-overexpressed NIH3T3) cells and B104-1-1 (neu*-transformed NIH3T3) cells, because a large number of the Shc/Grb2 complexes were detected. Associated protein complexes containing Shc were immunoprecipitated from actinomycin D-treated cell lysates with polyclonal anti-Shc antibody. Then the association with Grb2 was assessed by immunoblotting with monoclonal anti-Grb2 antibody. The result of the immunoblotting experiment revealed that actinomycin D inhibited Shc/Grb2 interaction in a dose-dependent manner in both B104-1-1 and EGF-stimulated SAA cells. The inhibition of Shc/Grb2 interaction by actinomycin D in B104-1-1 cells also reduced tyrosine phosphorylation of MAP kinase (Erk1/Erk2), one of the major components in the Ras-MAP kinase signaling pathway. These results suggest that actinomycin D could be a non-phosphorylated natural and cellular membrane-permeable SH2 domain antagonist.

Inhibition of chitin synthase II by catechins from stem bark of Taxus cuspidata.

Two flavonoids, (+/-)-catechin and (-)-epicatechin, were isolated from the stem bark of Taxus cuspidata by monitoring chitin synthase II inhibitory activity. The compounds inhibit chitin synthase II with an IC50 of 15 and 29 micrograms/ml, respectively and appear to be selective for chitin synthase II. They did not inhibit chitin synthase III.

Actinomycin D, C2 and VII, inhibitors of Grb2-SHC interaction produced by Streptomyces.

Actinomycin D, C2 and VII, cyclic peptides, inhibited Grb2 SH2 domain association (IC50 5-7 microM) with a phosphotyrosine containing peptide derived from the Shc protein (pTyr317). Actinomycins are the first examples of nonphosphorylated natural ligands of SH2 domain.