Antifungal chemical compounds identified using a C. elegans pathogenicity assay

There is an urgent need for the development of new antifungal agents. A facile in vivo model that evaluates libraries of chemical compounds could solve some of the main obstacles in current antifungal discovery. We show that Candida albicans, as well as other Candida species, are ingested by Caenorhabditis elegans and establish a persistent lethal infection in the C. elegans intestinal track. Importantly, key components of Candida pathogenesis in mammals, such as filament formation, are also involved in nematode killing. We devised a Candida-mediated C. elegans assay that allows high-throughput in vivo screening of chemical libraries for antifungal activities, while synchronously screening against toxic compounds. The assay is performed in liquid media using standard 96-well plate technology and allows the study of C. albicans in non-planktonic form. A screen of 1,266 compounds with known pharmaceutical activities identified 15 (approximately 1.2%) that prolonged survival of C. albicans-infected nematodes and inhibited in vivo filamentation of C. albicans. Two compounds identified in the screen, caffeic acid phenethyl ester, a major active component of honeybee propolis, and the fluoroquinolone agent enoxacin exhibited antifungal activity in a murine model of candidiasis. The whole-animal C. elegans assay may help to study the molecular basis of C. albicans pathogenesis and identify antifungal compounds that most likely would not be identified by in vitro screens that target fungal growth. Compounds identified in the screen that affect the virulence of Candida in vivo can potentially be used as "probe compounds" and may have antifungal activity against other fungi.

Galleria mellonella as a model host to study infection by the Francisella tularensis live vaccine strain

We used the killing of Galleria mellonella (Lepidoptera: Pyralidae; the greater wax moth) caterpillar by the live vaccine strain (LVS) of Francisella tularensis to develop an invertebrate host system that can be used to study F. tularensis infection and the in vivo effects of antibacterial compounds on F. tularensis LVS. After injection into the insect hemocoel, F. tularensis LVS, killed caterpillars despite the association of LVS with hemocytes. The rate of killing depended on the number of bacteria injected. Antibiotic therapy with ciprofloxacin, levofloxacin or streptomycin administered before or after inoculation prolonged survival and decreased the tissue burden of F. tularensis in the hemocoel. Delayed drug treatment reduced the efficacy of antibacterials and especially streptomycin. The G. mellonella-F. tularensis LVS system may facilitate the in vivo study of F. tularensis, efficacy with antibacterial agents.

A novel locus on 19q13 associated with autosomal-dominant macular dystrophy in a large Greek family

OBJECTIVE

To describe the clinical features of and genetic locus associated with autosomal-dominant macular dystrophy (MCDR5) in a large Greek family.

METHODS

26 members of a single family underwent clinical examinations and venepuncture. A genomewide linkage scan using 400 microsatellite markers distributed with an average spacing of 10 cM throughout the human genome.

RESULTS

14 members of the study family exhibited clinical features of the disease including decreased central vision and macular abnormalities in the posterior pole of the retina. Analysis of loci known to be associated with macular dystrophy did not show positive linkage. A genomewide linkage scan showed linkage to chromosome 19q, with a two-point maximum LOD score of 5.809 at theta = 0 between the disease and marker locus D19S412. On the basis of recombination events, the disease interval was localised between markers D19S420 and D19S540 on chromosome 19q, at a span of about 3.8 cM, in an area known to contain 120 known genes/transcripts. Eleven of these genes/transcripts were sequenced, and no disease-causing mutation was identified.

CONCLUSIONS

This study describes a new locus on 19q associated with autosomal-dominant macular dystrophy, designated as MCDR5. Additional study of other family members will be necessary to further narrow the interval and identify the responsible gene. The study of MCDR5 will aid in elucidation of the underlying pathogenic mechanisms for this and other macular diseases, including age-related macular degeneration.

Developments in the treatment of candidiasis: more choices and new challenges

The incidence of oesophageal candidiasis, candidaemia and disseminated candidiasis has increased dramatically. In addition to the amphotericin B formulations and fluconazole, the echinocandins anidulafungin, caspofungin and micafungin and the newer triazoles posaconazole and voriconazole are in the last stages of development and are becoming available for the management of candidiasis. This review presents these new agents and addresses their role in the treatment of candidiasis. All new antifungal agents exhibit potent activity against Candida spp. and echinocandins are fungicidal against most Candida spp. but appear to be less potent against certain species, such as Candida parapsilosis and C. guilliermondii. Systemic antifungal therapy can now be individualised based on the severity of the infection, comorbid conditions and the Candida spp. causing the infection. Studies are needed to investigate the possible development of resistance and the efficacy of these antifungal agents against the more resistant Candida spp.

New agents for the treatment of fungal infections: clinical efficacy and gaps in coverage

The incidence of fungal infections has increased globally, and the introduction of the newer triazoles and echinocandin antifungals is a more-than-welcome and long overdue development. In this report, we review the clinical trials evaluating the therapeutic efficacy of these new antifungal agents and examine possible gaps in coverage. Voriconazole has become the primary treatment for most forms of invasive aspergillosis in a number of centers, posaconazole offers a broad antifungal spectrum, and echinocandins are fungicidal against most Candida species. Moreover, the new agents are active against some fungi that are resistant to amphotericin B, may have a role in the management of fever and neutropenia, and provide exciting options for combination antifungal therapy. However, significant questions remain, including the management of breakthrough infections and treatment failures and the efficacy of the new antifungal agents against less common fungi.

Corynebacterium minutissimum endocarditis: a case report and review

We present a rare case of infectious endocarditis in a 40-year old male with native valve, caused by Corynebacterium minutissimum. The diagnosis was established with transesophageal echocardiogram. The patient was managed successfully with antibiotic therapy.

Newer triazole antifungal agents: pharmacology, spectrum, clinical efficacy and limitations

New triazole antifungals (voriconazole, posaconazole, ravuconazole and albaconazole) have been developed to meet the increasing need for new antifungals, and address the rising incidence of invasive fungal infections and the emergence of fungal resistance. This report describes the spectrum of activity of the newer-generation triazoles based on data from in vitro, animal and clinical studies. The authors discuss the use of these agents in combination with other antifungals, the extent of cross-resistance, their toxicity profile and pharmacokinetic properties. A total of two agents are currently available: voriconazole (which is becoming a primary treatment for the management of invasive aspergillosis) and posaconazole (which demonstrates a broad antifungal spectrum). A further two agents, albaconazole and ravuconazole, are undergoing early clinical evaluation and their future is uncertain. For all newer triazoles, concerns about emerging drug-resistant fungi and the incidence and management of breakthrough infections will dictate their role in antifungal prophylaxis and treatment.

Monogenic nonsyndromic otosclerosis: audiological and linkage analysis in a large Greek pedigree

OBJECTIVE

The aim of our study was to characterize the hearing impairment in a large multigenerational Greek family with autosomal dominant nonsyndromic otosclerosis and to perform genetic linkage analysis to known otosclerosis loci and collagen genes. In addition, we looked for mutations in the NOG gene to rule out congenital stapes ankylosis syndrome.

METHODS

Audiological analysis of the affected persons was based on multiple linear regression (MLR) analysis and construction of age-related typical audiograms (ARTA). Genotyping of microsatellite DNA polymorphisms for known otosclerosis (OTSC) loci or collagen genes and linkage analysis using the MLINK computer program were performed. The coding region of the NOG gene was screened for mutations by direct DNA sequencing.

RESULTS

The hearing loss in this family appears in childhood as conductive, but soon becomes mixed. Because the additional sensorineural component is progressive, this finally has lead to a pure sensorineural hearing loss in some family members, as the conductive component is masked. Audiological analysis showed an age-independent conductive component and a progressive frequency-specific sensorineural component. Linkage analysis excluded linkage to the four known otosclerosis loci (OTSC1, OTSC2, OTSC3, and OTSC5), as well as to the COL1A1 and COL1A2 genes. Mutation analysis of the coding region of the NOG gene did not reveal any disease causing mutation.

CONCLUSIONS

This study represents the first description of a detailed audiological analysis in a large pedigree segregating otosclerosis as a monogenic autosomal dominant trait. Exclusion of the four known otosclerosis loci in this family shows that monogenic otosclerosis is a genetically heterogeneous disease involving at least five different genes. A mutation in the NOG gene is not the underlying molecular mechanism of the early onset otosclerosis segregating in this family.

A LargeGLC1CGreek Family with a Myocilin T377M Mutation: Inheritance and Phenotypic Variability

PURPOSE

POAG is a complex disease; therefore, families in which a glaucoma gene has been mapped may carry additional POAG genes. The goal of this study was to determine whether mutations in the myocilin (MYOC) gene on chromosome 1 are present in two POAG families, which have previously been mapped to the GLC1C locus on chromosome 3.

METHODS

The three exons of MYOC were screened by denaturing (d)HPLC. Samples with heteroduplex peaks were sequenced. Clinical findings were compared with genotype status in all available family members over the age of 20 years.

RESULTS

A T377M coding sequence change in MYOC was identified in family members of the Greek GLC1C family but not in the Oregon GLC1C family. Individuals carrying both the MYOC T377M variant and the GLC1C haplotype were more severely affected at an earlier age than individuals with just one of the POAG genes, suggesting that these two genes interact or that both contribute to the POAG phenotype in a cumulative way.

Pneumocystis carinii pneumonia in patients with solid tumors and lymphomas: predisposing factors and outcome

AIM

The incidence of Pneumonocystis carinii pneumonia (PCP) is increasing in patients with cancer. The possible routes of transmission in this population, as well as the epidemiological data of PCP, are not very well understood. The collection and analysis of data concerning the predisposing factors for PCP will elucidate this subject.

PATIENTS AND METHODS

We studied 26 patients suffering from cancer who developed PCP during the five-year period 1997--2002.

RESULTS

Twenty-one patients had a solid tumor diagnosis while the remaining five had a lymphoma. All of them received intensive combination chemotherapy, while eight of them also received high-dose therapy and bone marrow transplantation. Nineteen of our patients had long hospitalization before the onset of PCP. All of them had received corticosteroids for various reasons. Among them, many patients had been exposed to radiotherapy and, in particular, in fields which encompass the major thoracic duct. Eighteen patients survived after the initiation of appropriate treatment, while eight others succumbed.

CONCLUSION

In this series, protracted deep lymphopenia, long hospitalization, radiotherapy and intensive chemotherapy were considered serious risk factors for developing PCP.

Refining the primary open-angle glaucoma GLC1C region on chromosome 3 by haplotype analysis

The GLC1C locus for primary open-angle glaucoma (POAG) is inherited as an autosomal dominant trait. This region on chromosome 3 is 11 cM long. DNA samples from members of a Greek and an American GLC1C family were obtained to determine whether additional typing of microsatellite markers in family members might narrow the region. GLC1C family members were evaluated clinically for POAG on the basis of open angles, intraocular pressures, cupping of discs, and visual fields. DNA samples from the Greek and Oregon GLC1C families were used to further refine the GLC1C region using microsatellite markers. A total of 22 affected members were identified in the two families. Common alleles for D3S3637 and D3S3612 were present in the disease haplotype from both families, suggesting that they may have a common founder. A newly diagnosed patient in the American family had a recombination in the distal portion of the GLC1C haplotype. This recombination narrows the GLC1C region from 11 to 4 cM.

Vinorelbine and docetaxel as first-line chemotherapy in metastatic breast cancer

PURPOSE

To evaluate the efficacy and tolerability of a combination of vinorelbine (VNR) and docetaxel (DOC) as first-line chemotherapy in patients with metastatic breast cancer.

PATIENTS AND METHODS

The study group comprised 40 women with untreated metastatic breast cancer with visceral (85%) and bone (70%) metastases. Of the 40 patients, 24 (60%) had previously received adjuvant chemotherapy, which had included anthracyclines in 12 patients (30%). Treatment consisted of VNR 25 mg/m(2) on days 1 and 5, and DOC 75 mg/m(2) on day 1 every 3 weeks. Depending on the neutrophil nadir (grade 3 or 4 neutropenia by WHO criteria) recombinant human granulocyte colony-stimulating factor (G-CSF) 5 micro g/kg on days 2-4 and 6-13 was given for all subsequent treatment cycles.

RESULTS

The overall response rate (ORR) was 40% (95% confidence interval, CI 15-65). Six patients (15%) achieved a complete response (CR) and ten patients (25%) achieved a partial response (PR). Stable disease (SD) was observed in six patients (15%), and 18 patients (45%) had progressive disease (PD). The median duration of response was 8 months and the median predictive time to progression (TTP) was 6 months. The main toxicity was neutropenia grade 3 and 4 in 28 patients (70%). Febrile neutropenia requiring hospitalization occurred in 12 patients (30%). Grade 3 or 4 anemia was seen in two patients (5%) and grade 3 or 4 thrombocytopenia was seen in one patient (2.5%). Severe nonhematologic toxicity, except alopecia, was uncommon and included stomatitis in two patients (5%), vomiting in two (5%) and diarrhea in one (2.5%). There were no treatment-related deaths.

CONCLUSIONS

The combination of VNR and DOC at the doses used in this study showed moderate activity as first-line chemotherapy in metastatic breast cancer. Neutropenia was considerable despite G-CSF administration.