Global VGIIa isolates are of comparable virulence to the major fatal Cryptococcus gattii Vancouver Island outbreak genotype

The ongoing cryptococcosis outbreak on Vancouver Island, BC, Canada, is caused by two VGII sub-genotypes of the primary pathogen, Cryptococcus gattii: VGIIa isolates predominate, whereas VGIIb isolates are rare. Although higher virulence of the VGIIa genotype has been proposed, an unresolved key question is whether VGIIa isolates from other regions are also more virulent than VGIIb isolates. We report the relationship between genotype and virulence for a global collection of C. gattii VGIIa and VGIIb isolates (from Australia, Argentina, Brazil, Canada, Thailand and the USA). In vitro and in vivo virulence studies were conducted. At 37°C, growth [at 18 h: 0.2 optical density (OD) difference, p 0.026; at 36 h: 0.6 OD difference, p 0.036) and mean melanin production (OD = 0.25 vs. OD = 0.15, p 0.059] of VGIIa isolates was greater than that of VGIIb isolates. The inhibitory effect of high temperature on melanin production of VGIIa isolates was less than that of VGIIb isolates (OD = 0.36 vs. OD = 0.69; p 0.001). Capsule production at 37°C of VGIIa isolates was less than that of VGIIb isolates. All VGIIa isolates were fertile, whereas only 17% of VGIIb isolates were fertile (p <0.001). In vivo virulence studies using the BALB/c mice nasal inhalation model revealed that VGIIa isolates were more virulent than VGIIb isolates (p <0.001) independent of their clinical (p 0.003) or environmental origin (p <0.001). This study established a clear association between genotype and virulence of the primary fungal pathogen, C. gattii.

Common atrioventricular canal in a foal

A 3-week-old Thoroughbred colt was presented for weakness and cyanosis. A pansystolic regurgitant murmur and other physical findings suggested that the foal developed pulmonary oedema as a consequence of congenital heart disease. A large atrial septal defect, a high ventricular septal defect and dysplasia of the atrioventricular valves were visualised echocardiographically. A persistent common atrioventricular canal was observed at necropsy.

Sequential opportunistic infections in two German Shepherd dogs

Two German Shepherd dogs with sequential opportunistic infections are described. The first was a 2-year-old male with cryptococcal rhinitis that spread to involve the optic nerves and brain. It was successfully treated with combination therapy utilising amphotericin B administered for 2 years, but the dog developed a disseminated Aspergillus deflectus infection 5 years later and was euthanased. The second case was a 4-year-old male that presented for a severe, deep-seated infection of the right antebrachium, with gradual extension to contiguous tissues. Neosartorya fischeri (anamorph; Aspergillus fischerianus) was isolated in pure culture and detected in histological sections. The infection was refractory to itraconazole, but resolved after amputation of the affected limb. Five months later, the dog developed a localised cutaneous lesion on the proximal pelvic limb, from which Pythium insidiosum was isolated and then visualised in tissue sections, together with a structure thought to be grass seed. This lesion was treated by wide surgical resection, although it was reported that the dog died of disseminated disease some months later. These cases provide further circumstantial evidence that young adult German Shepherd dogs have a predilection to developing invasive infections with fungi and other saprophytic pathogens.

Cryptococcosis in domestic animals in Western Australia: a retrospective study from 1995-2006

A retrospective study of cryptococcosis in domestic animals residing in Western Australia was conducted over an 11-year-period (from 1995 to 2006) by searching the data base of Murdoch University Veterinary Teaching hospital and the largest private clinical pathology laboratory in Perth. Cryptococcosis was identified in 155 animals: 72 cats, 57 dogs, 20 horses, three alpacas, two ferrets and a sheep. There was no seasonal trend apparent from the dates of diagnosis. Taking into account the commonness of accessions to Murdoch University, cats were five to six times more likely to develop this disease than dogs, and three times more likely than horses, while horses were almost twice as likely as dogs to become infected. Amongst the feline cohort, Ragdoll and Birman breeds were over-represented, while in dogs several pedigree breeds were similarly overrepresented. Dogs and horses tended to develop disease at an early age (one to five years), while cats were presented over a much wider range of ages. In cats and dogs the upper respiratory tract was the most common primary site of infection, while horses and alpacas tended to have lower respiratory involvement. The most striking finding of the study was the high frequency with which C. gattii was identified, with infections attributable to this species comprising 5/9 cats, 11/22 dogs, 9/9 horses and 1/1 alpaca, where appropriate testing was conducted. Preliminary molecular genotyping suggested that most of the C. gattii infections in domestic animals (9/9 cases) were of the VGII genotype. This contrasts the situation on the eastern seaboard of Australia, where disease attributable to C. gattii is less common and mainly due to the VGI genotype. C. gattii therefore appears to be an important cause of cryptococcosis in Western Australia.

Retinopathy: variable clinical spectrum and post-endarterectomy changes

BACKGROUND

The Carotid Artery Insufficiency Retinopathy (CAIR) is an uncommon sign of carotid artery obstruction. It is mainly found in patients with complete occlusion or severe obstruction of internal Carotid Artery (ICA). Retinopathy is caused by progressive and chronic hypoxia to ocular tissues. The purpose of the study is to describe the variable presentation of CAIR in patients with internal carotid artery stenosis and to asses the resolution of retinopathy in patients who had carotid endarterectomy.

METHODS

Records of the patients with confirmed internal carotid artery stenosis were reviewed. Patients' demographic data and way of presentation to ophthalmologist was recorded. Associated systemic vascular diseases were also recorded on the proforma. Records of the patients with confirmed internal carotid artery stenosis were reviewed.

RESULTS

Thirteen eyes of 10 patients were included in study with male to female ratio of 9:1. Patients' clinical presentation ranged from scattered blot haemorrhages to ocular ischemic syndrome. Patients presented with retinopathy at different stages. The presentation of retinopathy varied from scattered blot haemorrhages to ocular ischemic syndrome. Endarterectomy resolved CAIR in 2 out of 3 patients, with one patient having bilateral resolution.

CONCLUSION

CAIR should be suspected if retinopathy is unilateral. On the other hand patients with asymptomatic Carotid artery stenosis should be examined for signs of ocular ischemia. All patients with CAIR should be investigated for cardiovascular diseases. Endarterectomy in selected patients can resolve CAIR.

Spontaneous uterine rupture in a nulligravida female presenting with unexplained recurrent hematometra

Spontaneous rupture of an unscarred uterus in reproductive-age women is exceedingly rare, especially in the context of dysfunctional bleeding and a patent cervical canal. A 25-year-old nulligravida female, who reported recent onset of metromenorrhagia and anemia, was initially admitted for surgical management of unexplained hematometra requiring dilation and curettage. The patient remained with intermittent vaginal bleeding for the following six months on continuous progestin therapy. She then re-presented with enlarged hematometra and uterine rupture, which was surgically repaired. Despite exhaustive conservative treatment to preserve fertility, hysterectomy was eventually required due to recurrent uterine rupture. Idiopathic recurrent hematometra can result from the rare combination of uncontrolled dysfunctional bleeding and absence of outflow obstruction.

Successful treatment of cryptococcal pneumonia in a pony mare

A 20-year-old Welsh Mountain Pony (212 kg) mare was initially presented for a chronic cough, fever, weight loss and low grade abdominal pain. She later developed dyspnoea, tachypnoea and exercise intolerance. The presence of multiple masses (up to 17 cm diameter) in the pulmonary parenchyma was established using lateral thoracic radiography and transthoracic ultrasonography. Encapsulated, budding yeasts were observed in smears made from transtracheal washings and needle aspirates of the pulmonary lesions. Cryptococcus gattii (synonym: Cryptococcus neoformans variety gattii; Cryptococcus bacillisporus) was cultured from the transtracheal washings and aspirates of the lung masses. The pony was successfully treated using daily intravenous infusions of amphotericin B (typically 0.5 mg/kg in 1 L 5% dextrose in water over 1 h, following premedication with 50 mg flunixin intravenously) over a 1 month period, until a cumulative dose of 3 g had been administered. Treatment was considered to be successful on the basis of progressive improvement in clinical signs, reduction in the size of pulmonary cryptococcomas, 48 kg weight gain and a reduction in the cryptococcal antigen titre from 4096 to 256, 1 year after cessation of treatment.

Gene expression profile of ovalbumin-induced lung inflammation in a murine model of asthma

BACKGROUND

Asthma is a chronic inflammatory disease that is associated with airway hyperresponsiveness, tissue remodeling, and airway obstruction, and that involves coordinate expression of multiple inflammatory genes in the lungs.

OBJECTIVE

To evaluate the gene expression pattern in a mouse model of asthma and assess the effect of a new drug, R142571, on the gene expression profile.

METHODS

Lung tissue from ovalbumin-sensitized mice was used to examine gene expression on the CodeLink oligonucleotide mouse 20 K bioarray platform. Data were validated for some genes by semiquantitative reverse-transcriptase polymerase chain reaction.

RESULTS

Of the 19,736 genes represented on the microarray, expression of 378 genes was differentially regulated (215 upregulated and 163 downregulated), with at least a 2-fold change in expression (P <.05). The differentially regulated transcripts included genes known to be involved in several different biological processes, including signaling, DNA-dependent transcriptional regulation, immune response, proteolysis, and peptidolysis. Cluster analysis of the differentially regulated genes showed that at least 16 were downregulated by R142571 treatment at both of the doses used (1 and 10 mg/kg). In addition, 46 and 29 genes were downregulated at doses of 10 mg/kg and 1 mg/kg, respectively, as compared to the animals treated with vehicle.

CONCLUSION

The cytokine expression pattern in our data, suggests that the murine model exhibits a predominantlyT helper 2-type response, as observed in asthmatic human subjects. Based on this study, we suggest that this mouse model would be an appropriate system for screening new drug molecules for treatment of atopic asthma.

Long-term BRCA1 down-regulation by small hairpin RNAs targeting the 3' untranslated region

Mutations in the BRCA1 gene are responsible for the majority of hereditary breast/ovarian cancers. The functional significance of many mutations/splicing variants identified during the screening of high-risk individuals is difficult to predict due to the lack of in vitro functional tests correlating sequence variants with a risk of cancer development. RNA interference is a promising tool in analyzing functional properties of BRCA1 mutations. Here we designed and functionally analyzed shRNAs directed to 3'-UTR of BRCA1 mRNA that may be used to knock-down expression of endogenous BRCA1. Using retroviral infection, we achieved long-term down-regulation of BRCA1 in a cell-type specific manner. We propose that 3'-UTR-directed shRNAs, coupled with up-regulation of exogenous mutated BRCA1 variants, may constitute a versatile system for the functional analysis of BRCA1 gene alterations.