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

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.

Hepatitis B status in migrants and refugees: increasing health burden in Western Australia

BACKGROUND

In light of increasing migration from endemic countries with chronic hepatitis B (CHB), this study describes the changing epidemiology of CHB patients born outside Australia referred to a tertiary hospital in Western Australia. It aims to stratify risk and progression to cirrhosis and hepatocellular carcinoma according to viral factors and to provide an indication of the growing burden of disease and current and future treatment costs.

METHODS

Demographic, serological and biochemical data were obtained from patients with CHB between July 2002 and December 2008. Hepatitis B virus DNA quantification was performed to assess baseline viral loads in the patients. Total cost estimates for surveillance and treatment are based on probabilities of the population anticipated to be at a given stage of the disease in a given year.

RESULTS

There is a progressive increase in referrals (n=478) with the majority coming from Asia (57%) and Africa (35%). The mean age of Africans is 11 years less than that of Asians, with a lower proportion of Africans having hepatitis B virus DNA>2000 IU/mL compared with Asians (36.7% vs 54.3%). Approximately 50% of CHB patients referred are at risk of cirrhosis and hepatocellular carcinoma unless treated. Without treatment, a substantial increase in cost over 10 years (from $401,460 to $2,027,078) is estimated at 400%.

CONCLUSION

This study highlights the increasing burden of CHB in Western Australia, from people born in endemic countries, in particular, the direct costs of treatment. It will help to develop strategies that can be tailored to Western Australia with appropriate allocation of resources.

Tracking chromosome evolution in southern African gerbils using flow-sorted chromosome paints

Desmodillus and Gerbilliscus (formerly Tatera) comprise a monophyletic group of gerbils (subfamily Gerbillinae) which last shared an ancestor approximately 8 million years ago; diploid chromosome number variation among the species ranges from 2n = 36 to 2n = 50. In an attempt to shed more light on chromosome evolution and speciation in these rodents, we compared the karyotypes of 7 species, representing 3 genera, based on homology data revealed by chromosome painting with probes derived from flow-sorted chromosomes of the hairy footed gerbil, Gerbillurus paeba (2n = 36). The fluorescent in situ hybridization data revealed remarkable genome conservation: these species share a high proportion of conserved chromosomes, and differences are due to 10 Robertsonian (Rb) rearrangements (3 autapomorphies, 3 synapomorphies and 4 hemiplasies/homoplasies). Our data suggest that chromosome evolution in Desmodillus occurred at a rate of ~1.25 rearrangements per million years (Myr), and that the rate among Gerbilliscus over a time period spanning 8 Myr is also ~1.25 rearrangements/Myr. The recently diverged Gerbillurus (G. tytonis and G. paeba) share an identical karyotype, while Gerbilliscus kempi, G. afra and G. leucogaster differ by 6 Rb rearrangements (a rate of ~1 rearrangement/Myr). Thus, our data suggests a very slow rate of chromosomal evolution in Southern African gerbils.

Decreased IFNγ production correlates with diminished production of cytokines by dendritic cells in patients infected with hepatitis C virus and receiving therapy

Toll-like receptor (TLR) expression and the signalling pathways that lead to the production of accessory cytokines by antigen-presenting cells (APCs) both have potential to limit T-cell responses to viral antigens. Here, expression of TLR and retinoic acid inducible gene I (RIG-I) and responses evoked through these proteins were evaluated in patients chronically infected with HCV, before and during pegylated interferon-α (IFNα) and ribavirin therapy. Expression of TLR2, 3, 4, 7, 9 and RIG-I on APCs and cytokine production by DCs were measured by flow cytometry. Production of IL-12 by myeloid dendritic cells (mDCs), IFNα by plasmacytoid cells (pDCs) and IFNγ by peripheral blood mononuclear cells was measured after stimulation with TLR ligands. IFNγ ELISpot responses to HCV and CMV antigens declined on therapy. TLR and RIG-I expression on mDCs, pDCs, B cells and monocytes was either similar or higher in patients than that in controls and generally increased during therapy. Therapy impaired IL-12 and IFNα production by DCs and reduced production of IFNγ by PBMCs after stimulation with ligands for TLR3, TLR7/8, TLR9 and RIG-I. This was independent of whether patients attained a sustained virological response. HCV disease and interferon-based therapy reduced IFN-γ responses to HCV antigens and TLR agonists. This was not accompanied by reduced expression of pertinent TLR but correlated with diminished production of co-stimulatory cytokines by DCs stimulated via TLR.

A random comparative study of terbinafine versus griseofulvin in patients with tinea capitis in Western China

OBJECTIVE

To compare the efficacy and safety of terbinafine with griseofulvin in the treatment of tinea capitis in Western China.

METHODS

Children (2-14 years of age) with clinically diagnosed and potassium hydroxide microscopy-confirmed tinea capitis were randomized into three groups: group GRI4 received 4 weeks of griseofulvin; group TBF2 received 2 weeks of terbinafine; and Group TBF4 received 4 weeks of terbinafine. Clinical and mycological evaluations were done in 0, 2, 4, and 8 weeks and 1 year after therapy started. The isolated pathogenic fungi were evaluated for in vitro susceptibility by detecting the minimal inhibitory concentration (MIC) against terbinafine, griseofulvin, itraconazole, and ketoconazole.

RESULTS

The clinical effectiveness rate of GRI4, TBF2, and TBF4 were 100% (95% CI-confidence interval: 82-100%), 96.3% (95% CI: 81-100%), and 100%(95% CI: 85-100%), respectively, at week 8 and 100% after 1 year for the 3 groups; clinical cure rates were 84.2%(95% CI: 77-99%), 85.2%(95% CI: 71-98%), and 78.3%(95% CI: 61-95%), respectively, at week 8 and 100% after 1 year for all agents; mycological cure rates were 100%(95% CI: 74-100%), 95.0%(95% CI: 74-100%), and 94.1%(95% CI: 50-93%) at week 8 and 100% after 1 year for the 3 groups. In vitro, all patient-derived cultures were sensitive to the four antifungal agents.

CONCLUSION

Data from the clinical trial and in vitro antifungal activity indicated that terbinafine is efficacious and well tolerated in the treatment for Trichophyton infections (T. violaceum; Arthroderma vanbreuseghemii; and T. tonsurans) of the scalp, i.e., a 2- to 4-week course of terbinafine is as effective as a 4-week course of griseofulvin; in fact, a 2-week course of terbinafine is sufficient. Terbinafine is an effective alternative to griseofulvin against tinea capitis of Trichophyton infections.

Coenzyme Q plays opposing roles on bacteria/fungi and viruses in Drosophila innate immunity

Coenzyme Q (CoQ or ubiquinone) is a lipid-soluble component of virtually all types of cell membranes and has been shown to play multiple metabolic functions. Several clinical diseases including encephalomyopathy, cerebellar ataxia and isolated myopathy were shown to be associated with CoQ deficiency. However, the role of CoQ in immunity has not been defined. In the present study, we showed that flies defective in CoQ biosynthetic gene coq2 were more susceptible to bacterial and fungal infections, while were more resistant to viruses. We found that Drosophila contained both CoQ9 and CoQ10, and food supplement of CoQ10 could partially rescue the impaired immune functions of coq2 mutants. Surprisingly, wild-type flies fed CoQ10 became more susceptible to viral infection, which suggested that extra caution should be taken when using CoQ10 as a food supplement. We further showed that CoQ was essential for normal induction of anti-microbial peptides and amplification of viruses. Our work determined CoQ content in Drosophila and described its function in immunity for the first time.

Detection of myocardial perfusion abnormalities: standard dual-source coronary computed tomography angiography versus rest/stress technetium-99m single-photo emission CT

We compared coronary dual-source computed tomography angiography (corDSCTA) with technetium-99m single-photon emission computed tomography (SPECT) for the detection of myocardial perfusion abnormalities. Fifty-five consecutive patients underwent both gated myocardial perfusion SPECT and corDSCTA, the latter during a single arterial-phase injection of contrast agent. The perfusion defects visualised by corDSCTA correlated with the findings of rest/stress SPECT. Abnormal findings on stress SPECT, which were due to either ischaemia or infarct, were found in 24 patients. In comparison to SPECT at rest, corDSCTA detected perfusion defects with a sensitivity and specificity of 100% and 78%, respectively. Compared to SPECT at stress, the sensitivity and specificity values of corDSCTA were 83.3% and 90.3%, respectively. On corDSCTA , the average attenuation values of perfusion defects that corresponded to chronic infarcts (-8.5+/-22.2 HU) were significantly lower (p = 0.002) than those of non-infarct-related perfusion defects (43.1+/-17.5 HU). Using rest/stress SPECT is the gold standard for the diagnosis of myocardial ischaemia, corDSCTA was able to diagnose ischaemic disease (defined as the presence of high-grade stenotic CAD (>or=50% luminal narrowing)) with a sensitivity and specificity of 59% and 89%, respectively, in patients with no known history of myocardial infarction (n = 4). Thus, corDSCTA may serve as a diagnostic tool for the detection of perfusion abnormalities (first) visualised by SPECT. There appears to be a limited correlation between coronary stenotic disease and SPECT findings.

Factors affecting β-ODAP content in Lathyrus sativus and their possible physiological mechanisms

A neuroexcitatory non-protein amino acid, β-N-oxalyl-L-α,β-diaminopropionic acid (β-ODAP), present in the seeds of the hardy legume crop grass pea (Lathyrus sativus L.), was considered responsible for human lathyrism. The levels of β-ODAP were reported to vary in different tissues during plant development, and to be affected by a wide range of environmental stresses. In this paper, dynamic changes in β-ODAP level at specific stages of plant development as well as the influences of various environmental factors, including nutrient deficiency, drought, salinity, toxic heavy metals, and Rhizobium symbiosis on β-ODAP levels were analyzed, highlighting the relationship between changes in β-ODAP concentrations and Rhizobium growth. Possible mechanisms underlying β-ODAP accumulation are proposed and future research is suggested.

Could a loss of memory T cells limit responses to hepatitis C virus (HCV) antigens in blood leucocytes from patients chronically infected with HCV before and during pegylated interferon-alpha and ribavirin therapy?

The proportions and activation status of T cells may influence responses to hepatitis C virus (HCV) and treatment outcome in patients receiving pegylated interferon (IFN)-alpha/ribavirin therapy. We confirmed that IFN-gamma enzyme-linked immunospot (ELISPOT) responses to HCV are poor in HCV patients and showed that responses to HCV and cytomegalovirus (CMV) antigens decrease during therapy. This was most apparent in patients with sustained virological response (SVR). Baseline frequencies of CD4+ effector memory (TEM) T cells were lower in SVR than non-SVR. Proportions of CD4+ and CD8+ TEM and terminally differentiated effector memory (TEMRA) T cells declined on therapy in SVR, as did proportions of Fas+ CD8+ TEMRA T cells. Baseline frequencies of programmed death (PD)-1-expressing CD4+ TEM and TEMRA T-cells were higher in SVR. Therapy increased percentages of PD-1+ CD4+ central memory (TCM) T cells and PD-1+ CD8+ TEM and TEMRA T cells in SVR. We conclude that successful therapy depletes circulating antigen-specific CD4+ T cell responses. This paralleled decreases in proportions of effector memory T cells and higher percentages of CD4+ TCM T cells expressing PD-1.

Early Diagnosis of Acute Myocardial Infarction by Bedside Multimarker Test at an Emergency Department in Hong Kong

Introduction

Cardiac biomarker measurement can aid diagnosis of acute myocardial infarction. The present study evaluates the efficacy and efficiency of point-of-care multimarkers measurement of myoglobin, creatine kinase (CK-MB) and troponin in identifying patients with acute myocardial infarction.

Method

We prospectively enrolled consecutive patients (N=105) in the emergency department who were being evaluated for possible acute myocardial infarction. Point-of-care testing (POCT) of myoglobin, CK-MB and troponin I (TnI) was performed in all patients. Central laboratory measurement of troponin I was also performed simultaneously. The sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio and receiver operating characteristic (ROC) curve were evaluated.

Result

The specificity and positive likelihood ratio of TnI (POCT) and TnI (laboratory) were 98%, 13.0 and 98%, 21.8 respectively. The areas under curve of the ROC curve of TnI (POCT) and TnI (laboratory) were 0.692 and 0.725 respectively.

Conclusion

A high positive likelihood ratio for acute myocardial infarction through point-of-care testing can help timely diagnosis and just-in-time appropriate management for patients presenting with chest pain.