Inhibition effect of tea tree oil on Listeria monocytogenes growth and exotoxin proteins listeriolysin O and p60 secretion.

Listeria monocytogenes (L. monocytogenes) is a Gram-positive bacterium that causes infections in humans. In this study, the effects of tea tree oil (TTO) at subinhibitory concentrations on L. monocytogenes growth and two important exotoxin proteins secreted by L. monocytogenes were researched. Treatment with half of minimal inhibitory concentration of TTO demonstrated very little or no reduction in numbers of viable ATCC 19115 cells. Listeriolysin O (LLO) and p60, were investigated. A listeriolysin assay was used to investigate the hemolytic activities of L. monocytogenes exposed to TTO, and the secretion of LLO and p60 was detected by immunoblot analysis. Additionally, real-time RT-PCR was used to analyse the influence of TTO on the transcription of LLO and p60 encoded genes hly and iap respectively. According to our experimental results, we propose that TTO could be used as a promising natural compound against L. monocytogenes and its virulence factors. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report on the influence of subinhibitory concentrations of tea tree oil (TTO) on the secretion of listeriolysin O (LLO) and p60, the critical virulence factors involved in Listeria pathogenesis. The results showed that TTO at 0·25 mg ml-1 reduced the secretion of LLO and p60 to 10 and 34·9% respectively, in addtion, the transcription of hly and iap was reduced to 10 and 4·3% at 0·5 mg ml-1 respectively. We propose that TTO could be used as a promising antimicrobial compound and virulence inhibitor against L. monocytogenes.

In vitro activity of isoimperatorin, alone and in combination, against Mycobacterium tuberculosis.

UNLABELLED: Previous studies have shown that isoimperatorin (IO), a furanocoumarin isolated from several medicinal plants, has antimycobacterial activity against Mycobacterium tuberculosis strain H37Rv (ATCC 27294). This study demonstrated that IO has antimycobacterial activity against 2 drug-sensitive and 6 drug-resistant isolates, with minimum inhibitory concentrations (MICs) of 50-100 µg ml(-1) and 100-200 µg ml(-1), respectively. IO exhibited synergistic antimycobacterial effects with rifampin (RMP), isoniazid (INH) and ethambutol (EMB) against 6 drug-resistant strains, with fractional inhibitory concentration index (FICI) values of 0·133-0·472, 0·123-0·475 and 0·124-0·25, respectively. The IO/RMP, IO/INH and IO/EMB combination treatments had synergistic effects or no interaction in the 2 drug-sensitive strains and the standard strain ATCC 27294. The synergism of combined drugs against drug-resistant strains was better than drug-sensitive strains. No antagonism was observed in with the aforementioned combinations against all strains tested. IO exhibited relatively low cytotoxicity to Vero cells. Our results indicate that IO may serve as promising a template for future antimycobacterial drug development. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report on the in vitro synergistic antimycobacterial effects of isoimperatorin (IO) in combination with three first-line drugs: rifampin (RMP), isoniazid (INH) and ethambutol (EMB). The results indicated that the antimycobacterial activity of IO was modest; however, IO was a useful and effective agent against Myco. tuberculosis when it was combined with first-line antimycobacterial drugs and is worthy of further development as a lead compound for the development of novel antimycobacterial therapeutic agents.

Blockade of micro-opioid receptors in the medial thalamus inhibits acquisition, but not expression, of morphine-induced conditioned place preference.

The medial thalamus contains abundant mu-opioid receptors and is activated by acute morphine administration. However, the role of the medial thalamus in the rewarding effects of morphine is unclear. The present study examined whether mu-opioid receptors of the medial thalamus influenced the acquisition and expression of morphine-induced conditioned place preference (CPP) in rats. An unbiased apparatus and biased subject assignment were used. Administration of morphine in increasing doses (2 mg/kg, 4 mg/kg, 6 mg/kg, 10 mg/kg, s.c.) was paired with an initially non-preferred chamber and saline administration was paired with an initially preferred chamber. Conditioning trials were conducted twice daily for 4 days. Microinjection of the irreversible mu-opioid receptor antagonist, beta-funaltrexamine (5 microg/rat), into the medial thalamus 23 h prior to each morphine conditioning completely blocked the acquisition of CPP. However, microinjection of beta-funaltrexamine into the medial thalamus after morphine conditioning trials, but 23 h prior to a test session, had no effect on the expression of CPP. It is concluded that mu-opioid receptors in the rat medial thalamus are involved in the acquisition, but not expression, of morphine-induced CPP.

Effect of prenatal exposure to polychlorinated biphenyls on cognitive development in children: a longitudinal study in Taiwan.

BACKGROUND: From 1978 to 1979, a group of people in Taiwan were exposed to high levels of heat-degraded polychlorinated biphenyls (PCBs) owing to accidental ingestion of contaminated rice oil. Children born to mothers following the exposure ('Yucheng' children) were known to have hyperpigmented skin and other dysmorphology after birth. AIMS: To determine the effect of prenatal exposure to PCBs on cognitive development in Yucheng children. METHOD: One hundred and eighteen Yucheng children prenatally exposed to PCBs and degradation products, and community-matched control children who were exposed to background levels only, were followed from 1985 to 1998. The Bayley Scale for Infant Development, Chinese version of the Stanford-Binet IQ Test, Raven's Coloured Progressive Matrices and Raven's Standardised Progressive Matrices were used to assess the cognitive development of these children. RESULTS: The Yucheng children scored lower than control children on each of these methods of measurement between the ages of 2 and 12 years. CONCLUSIONS: Prenatal exposure to PCBs and their derivatives has long-term adverse effects on cognitive development in humans.

[A study on processing of the root of Astragalus membranaceus Bge. by HPLC].

The paper presents a study on the drug-processing of the root of Astragalus membranaceus. A HPLC method for the determination of astragaloside IV in its processed products has been established. The recovery is 96.1% and the RSD is 2.15%.

Specific induction of fibronectin binding activity by hemoglobin in Candida albicans grown in defined media.

Fibronectin (FN) is a major component of host extracellular matrix that may play an important role in the initiation and dissemination of Candida albicans infections. Expression of FN binding requires growth of C albicans blastoconidia in complex medium, and the regulation of FN receptor expression is poorly understood. We now demonstrate that hemoglobin is a potent and specific inducer of FN receptor expression and describe a defined medium supplemented with hemoglobin that greatly and stably enhances the binding activity of C. albicans for soluble FN. Enhancement of FN binding by hemoglobin in strain 44807 was concentration dependent and was maximal at 0.1% hemoglobin with 20- to 80-fold enhancement. The hemoglobin-induced FN binding to C. albicans was saturable, with a Kd of 2.7 X 10(-8) M. Enhancement required growth of C. albicans in hemoglobin-containing medium, since simply exposing blastoconidia to hemoglobin in a nongrowing status did not enhance binding. Induction was reversible following removal of hemoglobin from the growth medium and not associated with germination. Inorganic or protein-bound iron was not sufficient for the induction, since other iron-containing proteins or inorganic iron salts were inactive. Growth in the simple medium yeast nitrogen base supplemented with hemoglobin increased cell adhesion to immobilized FN and to cultured monolayers of bovine corneal endothelial cells. These data suggest that hemoglobin may be an important regulator of FN binding activity in C. albicans and thus may play a role in its pathogenesis.

Demonstration of the anti-viral activity of garlic extract against human cytomegalovirus in vitro.

The in vitro anti-viral activity of garlic extract (GE) on human cytomegalovirus (HCMV) was evaluated by tissue culture, plaque reduction and early antigen assay. A dose dependent inhibitory effect of GE was evident when GE was applied simultaneously with HCMV. But the effect was stronger when the monolayers were pretreated with GE. In addition, the anti-viral effect of GE persisted long in infected cells after its being removed from the culture medium. The strongest anti-viral effect of GE was demonstrated when it was applied continuously. It is therefore recommended that clinical use of GE against HCMV infection should be persistent and the prophylactic use of GE is preferable in immunocompromised patients.

Allogeneic bone marrow transplantation for the treatment of leukemia.

Eighteen patients with leukemia have received HLA-identical allogeneic bone marrow transplantation (BMT) at our hospital since 1981. Fifteen of these patients have been living without relapse. for prophylaxis of GVHD, MTX was used in 8 patients, and cyclosporine (CSP) together with MTX in 6 patients, 3 received multiple agents at much smaller dosage, including monoclonal antibody. All patients received intravenous placental gamma-globulin, and 16 received garlic extract. Three patients died. One, who neither received MTX, nor CSP died of hyperacute GVHD, one who did not receive garlic extract died of GMV pneumonia, and the third one died of tuberculosis 18 months after BMT.

Experimental and clinical investigation on oxiconazole.

A new antimycotic imicazole drug, oxiconazole, used both in vitro and in vivo in the treatment of 212 cases of tinea corporis, tinea cruris and tinea pedis is reported. In vitro, it shows marked antimycotic effect against 24 strains of pathogenic fungi except those of Wangiella dermatitides and 3 strains of Aspergilli. The minimal inhibition concentration (MIC) to Epidermophyton floccosum and Candida guilliermondi are 1 microgram/ml and 0.5 microgram/ml. The cure rate of 2% cream of oxiconazole in 124 cases of tinea corporis and tinea cruris is 90.3%, and in 88 cases of tinea pedis, 89.78%.