Advanced genetic techniques in fungal pathogen research

Although fungi have been important model organisms for solving genetic, molecular, and ecological problems, recently, they are also becoming an important source of infectious disease. Despite their high medical burden, fungal pathogens are understudied, and relative to other pathogenic microbes, less is known about how their gene functions contribute to disease. This is due, in part, to a lack of powerful genetic tools to study these organisms. In turn, this has resulted in inappropriate treatments and diagnostics and poor disease management. There are a variety of reasons genetic studies were challenging in pathogenic fungi, but in recent years, most of them have been overcome or advances have been made to circumvent these barriers. In this minireview, we highlight how recent advances in genetic studies in fungal pathogens have resulted in the discovery of important biology and potential new antifungals and have created the tools to comprehensively study these important pathogens.

Phenotypic characterization of HAM1, a novel mating regulator of the fungal pathogen Cryptococcus neoformans

Cryptococcus neoformans is a fungal pathogen responsible for >200,000 yearly cases with a mortality as high as 81%. This burden results, in part, from an incomplete understanding of its pathogenesis and ineffective antifungal treatments; hence, there is a pressing need to understand the biology and host interactions of this yeast to develop improved treatments. Protein palmitoylation is important for cryptococcal virulence, and we previously identified the substrates of its main palmitoyl transferase. One of them was encoded by the uncharacterized gene CNAG_02129. In the filamentous fungus Neurospora crassa, a homolog of this gene named HAM-13 plays a role in proper cellular communication and filament fusion. In Cryptococcus, cellular communication is essential during mating, therefore we hypothesized that CNAG_02129, which we named HAM1, may play a role in mating. We found that ham1Δ mutants produce more fusion products during mating, filament more robustly, and exhibit competitive fitness defects under mating and non-mating conditions. Additionally, we found several differences with the major virulence factor, the polysaccharide capsule, that may affect virulence, consistent with prior studies linking virulence to mating. We observed that ham1Δ mutants have decreased capsule attachment and transfer but exhibit higher amounts of exopolysaccharide shedding and biofilm production. Lastly, HAM1 expression is significantly lower in mating media relative to non-mating conditions, consistent with it acting as a negative regulator of mating. Understanding the connection between mating and virulence in C. neoformans may open new avenues of investigation into ways to improve the treatment of this disease.

PIK3CA dependence and sensitivity to therapeutic targeting in urothelial carcinoma

Background

Many urothelial carcinomas (UC) contain activating PIK3CA mutations. In telomerase-immortalized normal urothelial cells (TERT-NHUC), ectopic expression of mutant PIK3CA induces PI3K pathway activation, cell proliferation and cell migration. However, it is not clear whether advanced UC tumors are PIK3CA-dependent and whether PI3K pathway inhibition is a good therapeutic option in such cases.

Methods

We used retrovirus-mediated delivery of shRNA to knock down mutant PIK3CA in UC cell lines and assessed effects on pathway activation, cell proliferation, migration and tumorigenicity. The effect of the class I PI3K inhibitor GDC-0941 was assessed in a panel of UC cell lines with a range of known molecular alterations in the PI3K pathway.

Results

Specific knockdown of PIK3CA inhibited proliferation, migration, anchorage-independent growth and in vivo tumor growth of cells with PIK3CA mutations. Sensitivity to GDC-0941 was dependent on hotspot PIK3CA mutation status. Cells with rare PIK3CA mutations and co-occurring TSC1 or PTEN mutations were less sensitive. Furthermore, downstream PI3K pathway alterations in TSC1 or PTEN or co-occurring AKT1 and RAS gene mutations were associated with GDC-0941 resistance.

Conclusions

Mutant PIK3CA is a potent oncogenic driver in many UC cell lines and may represent a valuable therapeutic target in advanced bladder cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2570-0) contains supplementary material, which is available to authorized users.

Rural and urban problem drinkers in six Southern states

In 1994-1997 we conducted a four-wave longitudinal study of rural and urban problem drinkers in six Southern United States states to examine rural/urban differences in predictors of service use and course of drinking. This report describes early rural/urban differences from a brief interview with over 3,000 community individuals and among 525 identified problem drinkers. Overall, we found rural/urban differences in alcohol consumption at the community level but only demographic differences among problem drinkers. Our newly developed screening interview for alcohol disorders had excellent agreement (kappa = 0.72) for lifetime disorders and good agreement (kappa = 0.53) for recent disorders against structured diagnostic interviews for DSM-IV criteria.

Utilization of acute inpatient services for alcohol detoxification

This study indicates that the majority of patients admitted to VA hospitals for medical detoxification could have those services provided on an outpatient or less intensive basis. However, inpatient medical detoxification services appear to be appropriate for those alcoholics at risk for potential life-threatening complications of withdrawal such as delirium tremens, or those with concurrent associated medical conditions such as pancreatitis, gastrointestinal bleeding, or complications of cirrhosis. Data were obtained from a national random sample of hospitalizations in Department of Veterans Affairs (VA) inpatient medical and surgical units. Medical records for 144 alcoholism-related medical admissions to 35 VA medical centers were reviewed using the Appropriateness Evaluation Protocol (AEP), a clinically based utilization review instrument widely used in the private sector. The medical records for the admission and each day of medical/surgical inpatient stay were reviewed using clinical criteria for the appropriateness of acute inpatient care as opposed to lower levels of care.

Does this treatment work? Validation of an outcomes module for alcohol dependence

The purpose of this study was to evaluate the outcomes of routine care administered to alcohol-dependent inpatients. The authors sought to validate a self-administered instrument that measures the types and extent of care delivered, the outcomes of that care, and casemix characteristics that influence the outcomes of care. Seventy-eight patients who were beginning inpatient treatment for alcohol dependence were recruited; 85% were followed 5 months later to examine cross-sectional and longitudinal relationships to gold standard assessments. The self-administered module demonstrated excellent agreement with structured interview assessments of diagnosis (kappa = .81), remission (kappa = .83), and change in severity of alcohol-related problems (r = .66 to .87). Casemix variables, particularly baseline severity, predicted change in alcohol consumption and functional status. The baseline module required 20 minutes for the average patient and 5 minutes for the average clinician to complete, with less than 2% missing data. Results indicated that the module measures key constructs with sufficient precision to assist clinicians and researchers in characterizing the degree to which routine inpatient care for alcohol dependence "works" in their patient population. The entire module is in the public domain and available free of charge to interested users.

Psychiatrists' compliance with nonpsychiatric consultations: does compliance affect concordance?

Utilizing a systematic methodology (The Consultation-Liaison Outcome Evaluation System), the compliance of nonpsychiatric consultations within a general hospital psychiatric unit staffed by private practitioners was assessed. Thirty-one percent of the patients received such consultations and these patients had a longer length of stay than those without a consultation. Psychiatrists were generally compliant with both medication and diagnostic recommendations; but in only half the discharge summaries was the consultant's primary medical diagnosis fully reflected. The implications of these data are discussed.

Solvent systems for intracarotid 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) infusion

The agent, 1,3-bis(3-chloroethyl)-1-nitrosourea (BCNU), when given by arterial infusion for brain tumor chemotherapy is usually dissolved in an alcohol/saline solution. The authors compared the osmolality of and drug recovery from solvent systems of alcohol/saline, dimethyl sulfoxide (DMSO)/water, and dextrose/water. Recovery of drug was adequate from all solvent systems, although variability of drug recovery from the alcohol/saline and DMSO/water systems was greater than from the dextrose/water system. The alcohol/saline system was significantly hyperosmolar. The alcohol/saline and DMSO/water solvent systems offer no advantage over the dextrose/water system and may be associated with significant disadvantages.

Supraophthalmic carotid infusion for brain-tumor chemotherapy. Technical note

The ocular complications of intracarotid infusion of drugs for brain-tumor chemotherapy may be eliminated by infusion of the chemotherapeutic agent into the carotid artery above the origin of the ophthalmic artery. The authors have developed a catheter that can negotiate the carotid siphon. This catheter is not balloon-tipped but incorporates a flexible tip with an expanded end to facilitate drag by flowing blood. The exit hole is placed to allow remote manipulation of the tip by hydraulic forces. Using this catheter, the authors have been consistently able to infuse the supraophthalmic carotid artery.