Genomic analysis of severe hypersensitivity to hygromycin B reveals linkage to vacuolar defects and new vacuolar gene functions in Saccharomyces cerevisiae

The vacuole of Saccharomyces cerevisiae has been a seminal model for studies of lysosomal trafficking, biogenesis, and function. Several yeast mutants defective in such vacuolar events have been unable to grow at low levels of hygromycin B, an aminoglycoside antibiotic. We hypothesized that such severe hypersensitivity to hygromycin B (hhy) is linked to vacuolar defects and performed a genomic screen for the phenotype using a haploid deletion strain library of non-essential genes. Fourteen HHY genes were initially identified and were subjected to bioinformatics analyses. The uncovered hhy mutants were experimentally characterized with respect to vesicular trafficking, vacuole morphology, and growth under various stress and drug conditions. The combination of bioinformatics analyses and phenotypic characterizations implicate defects in vesicular trafficking, vacuole fusion/fission, or vacuole function in all hhy mutants. The collection was enriched for sensitivity to monensin, indicative of vacuolar trafficking defects. Additionally, all hhy mutants showed severe sensitivities to rapamycin and caffeine, suggestive of TOR kinase pathway defects. Our experimental results also establish a new role in vacuolar and vesicular functions for two genes: PAF1, encoding a RNAP II-associated protein required for expression of cell cycle-regulated genes, and TPD3, encoding the regulatory subunit of protein phosphatase 2A. Thus, our results support linkage between severe hypersensitivity to hygromycin B and vacuolar defects.

Candidaemia with uncommon Candida species: predisposing factors, outcome, antifungal susceptibility, and implications for management

The risk factors for and clinical features of bloodstream infection with uncommon Candida spp. (species other than C. albicans, C. glabrata, C. parapsilosis, C. tropicals and C. krusei) are incompletely defined. To identify clinical variables associated with these species that might guide management, 57 cases of candidaemia resulting from uncommon Candida spp. were analysed in comparison with 517 episodes of Candida albicans candidaemia (2001-2004). Infection with uncommon Candida spp. (5.3% of candidaemia cases), as compared with C. albicans candidaemia, was significantly more likely to be outpatient-acquired than inpatient-acquired (15 of 57 vs. 65 of 517 episodes, p 0.01). Prior exposure to fluconazole was uncommon (n=1). Candida dubliniensis was the commonest species (n=22, 39%), followed by Candida guilliermondii (n=11, 19%) and Candida lusitaniae (n=7, 12%).C. dubliniensis candidaemia was independently associated with recent intravenous drug use (p 0.01) and chronic liver disease (p 0.03), and infection with species other than C. dubliniensis was independently associated with age<65 years (p 0.02), male sex (p 0.03) and human immunodeficiency virus infection (p 0.05). Presence of sepsis at diagnosis and crude 30-day mortality rates were similar for C. dubliniensis-related, non-C. dubliniensis-related and C. albicans-related candidaemia. Haematological malignancy was the commonest predisposing factor in C. guilliermondii (n=3, 27%) and C. lusitaniae (n=3, 43%) candidaemia. The 30-day mortality rate of C. lusitaniae candidaemia was higher than the overall death rate for all uncommon Candida spp. (42.9% vs. 25%, p not significant). All isolates were susceptible to amphotericin B, voriconazole, posaconazole, and caspofungin; five strains (9%) had fluconazole MIC values of 16-32 mg/L. Candidaemia due to uncommon Candida spp. is emerging among hospital outpatients; certain clinical variables may assist in recognition of this entity.

Candidemia following solid organ transplantation in the era of antifungal prophylaxis: the Australian experience

Solid organ transplant (SOT) recipients have high rates of invasive fungal infections, with Candida species the most commonly isolated fungi. The aim of this study was to identify differences between incidence rates, risk factors, clinical presentations, and outcomes of candidemia in SOT recipients and non-SOT patients. Data from the multicenter prospective Australian Candidaemia Study were examined. From August 2001 to July 2004, 24 episodes (2.2%; 24/1068) of candidemia were identified in SOT recipients. During this period, the numbers of transplanted organs included liver (n=455), kidney (n=1605), single lung (n=57), bilateral lung (n=183), heart and lung (n=18), heart (n=157), and pancreas (n=62). The overall annual estimated incidence of candidemia in SOT recipients was higher (3 per 1000 transplant admissions) than in non-SOT patients (incidence 0.21 per 1000 admissions; P<0.001). The incidence and timing of candidemia post transplant was influenced by the transplanted organ type, with the majority of episodes (n=14, 54%) occurring >6 months after renal transplantation. Risk factors for candidemia in the month preceding diagnosis were similar to non-SOT recipients except for corticosteroid therapy (P<0.001). Antifungal prophylaxis did not select for more resistant or non-albicans Candida species in the SOT group. The 30-day all-cause mortality was similar to non-SOT patients with candidemia and remains high at 21%. All deaths in SOT recipients occurred early (within 5 days of diagnosis), underlining a need for better diagnostic tests, targeted prevention, and early treatment strategies.

The clinical scaphoid fracture: early computed tomography as a practical approach

INTRODUCTION

Up to 40% of scaphoid fractures are missed at initial presentation as clinical examination and plain radiographs are poor at identifying scaphoid fractures immediately after the injury. Avoiding a delay in diagnosis is essential to prevent the risk of non-union and early wrist arthritis. We demonstrate the use of CT scanning for the early confirmation of a scaphoid fracture.

PATIENTS AND METHODS

We conducted a retrospective, chronological review of patients who attended an upper limb fracture clinic from January 2001 to October 2003 in a small district general hospital. We performed a CT scan on all 'clinical scaphoid' patients who had negative plain X-ray films.

RESULTS

Overall, 70% of patients had a CT scan within 1 week of injury and not from date of accident and emergency attendance; 83% of patients had a CT scan within 2 weeks of injury. Of 118 patients identified, 32% had positive findings and 22% of 'clinical scaphoid' patients had scaphoid fractures. The proportion of positive findings for an acute scaphoid fracture was 68%. Additional pathologies identified on CT were capitate, triquetral and radial fractures.

CONCLUSIONS

Our audit shows that it is practical to perform CT on suspicious scaphoid fractures in a small district general hospital. We identified an extremely high false-negative rate for plain X-rays and demonstrate that the appropriate use of CT at initial fracture clinic attendance with 'clinical scaphoid' leads to an earlier diagnosis and reduces the need for prolonged immobilisation and repeated clinical review.

Differential inflammatory activation of IL-6 (−/−) astrocytes

IL-6 is a major immunomodulatory cytokine with neuroprotective activity. The absence of interleukin-6 (IL-6) results in increased vulnerability of dopaminergic neurons to the neurotoxicant, MPTP, and a compromised reactive microgliosis. To determine how astrogliosis may contribute to nigrostriatal degeneration in IL-6 (-/-) mice, the inflammatory profiles of astrocytes of IL-6 genotype were compared. Fourteen cytokines and four chemokines were simultaneously assayed in the supernatants of LPS-stimulated primary astrocyte cultures. In a time course of 6, 18 and 48 h and LPS stimulations of 0, 0.1, 1, 10 and 100 ng/ml, IL-6 (-/-) astrocytes secreted significantly greater amounts of the pro-inflammatory cytokines IL-1alpha, IL-1beta and TNFalpha than did IL-6 (+/+) cells. Elevated levels of IL-10 and IL-12p40 were only detected at 48 h post-stimulation with greater IL-10 in IL-6 (-/-) supernatants and greater IL-12p40 in IL-6 (+/+) supernatants. IL-6 (+/+) astrocytes produced more G-CSF and GM-CSF when compared with IL-6 (-/-) astrocytes. Chemokine levels were greater in supernatants of IL-6 (+/+) astrocytes than IL-6 (-/-) cells prior to 48 h post-stimulation. At that time, higher levels of MIP-1alpha were maintained in IL-6 (+/+) supernatant, while similar levels of MCP-1 in supernatants of both IL-6 (+/+) and IL-6 (-/-) cells were measured. Additionally, LPS (100 ng/ml) resulted in greater levels of KC and Rantes in IL-6 (-/-) astrocyte supernatants compared with IL-6 (+/+) supernatants at that time. These results suggest that the autocrine modulatory activities of IL-6 affect multiple cytokine secretory pathways, which could participate in neurodegenerative processes.

Toxicity and Efficacy of Concurrent Gemcitabine and Radiotherapy for Locally Advanced Pancreatic Cancer

Gemcitabine has been demonstrated to be a potentradiosensitizer in the laboratory and in the clinic (1-7)and has proven clinical systemic activity to pancreaticcancer. Responses to systemic gemcitabine inpatients with metastatic pancreatic adenocarcinomahave been documented in phase I, phase II, and phaseIII clinical settings (8,9). Moreover, a recent randomizedtrial of gemcitabine vs 5-FU as first-linetherapy in patients with advanced pancreatic adenocarcinomademonstrated a modest median survivalbenefit (4.41 vs 5.65 mo,p= 0.0025) for those patientswho received gemcitabine compared to those whoreceived 5-FU (10). In addition, gemcitabine wasshown to improve cancer-related symptoms and performancestatus as assessed by a quantitative clinicalbenefit scale in both untreated and previouslytreated patients with metastatic adenocarcinoma ofthe pancreas (10,11). Based on these data, the FDAapproved gemcitabine as a first-line agent for patientswith advanced adenocarcinoma of the pancreas.

Is the therapeutic index better with gemcitabine-based chemoradiation than with 5-fluorouracil-based chemoradiation in locally advanced pancreatic cancer?

PURPOSE

To retrospectively compare the toxicity and efficacy of concurrent gemcitabine-based chemoradiation with that of concurrent 5-fluorouracil (5-FU)-based chemoradiation in patients with unresectable pancreatic cancer.

PATIENTS AND METHODS

Between September 1996 and May 2000, 114 patients with localized unresectable adenocarcinoma of the pancreas were treated with concurrent chemoradiation. Locally advanced unresectable disease was defined as low-density tumor in contact with the superior mesenteric artery (SMA) or celiac artery, or occlusion of the superior mesenteric-portal venous confluence. Fifty-three patients were selected to receive gemcitabine in 7 weekly cycles (250-500 mg/m(2)) with concurrent radiotherapy (median dose 30 Gy, range 30-33 Gy in 10-11 fractions). The remaining 61 patients received continuous-infusion 5-FU (200-300 mg/m(2)) with concurrent radiotherapy (30 Gy in 10 fractions). Radiotherapy was delivered to the primary tumor and regional lymphatics. Patients receiving gemcitabine and those receiving 5-FU had a similar mean Karnofsky performance status (KPS, 89% vs. 86%), distribution of tumor grade (43% vs. 33% poorly differentiated), and percent weight loss (all p = NS). However, patients treated with gemcitabine had a significantly larger median maximum cross-sectional tumor area (TA, 8.8 cm(2) vs. 5.7 cm(2), p = 0.046) and were significantly younger (median age 60 vs. 68 years, p <0.001). Severe acute toxicity (ST) was defined as toxicity requiring a hospital stay of more than 5 days, mucosal ulceration with bleeding, more than 3 dose deletions of gemcitabine or discontinuation of 5-FU, or toxicity resulting in surgical intervention or death. Kaplan-Meier analysis was used to calculate the actuarial rate of local progression on imaging (LP), the rate of distant metastasis (DM), and the overall survival (OS) rate. The imaging was reviewed in resected patients.

RESULTS

Patients receiving gemcitabine developed significantly more ST during treatment (23% vs. 2%, p < 0.0001) than did those receiving 5-FU. Patients treated with gemcitabine had a similar 10-month LP rate (62% vs. 61%), 10-month DM rate (55% vs. 47%), 1-year OS rate (42% vs. 28%), and median OS duration (11 months vs. 9 months) to patients treated with 5 FU (all p = NS). Five patients who received gemcitabine and 1 patient who received 5-FU underwent margin-negative pancreaticoduodenectomy after chemoradiation. Three patients had a short segment (<or= 1 cm in length) of low-density tumor abutting the SMA, 1 had involvement of the common hepatic artery, and 1 had a short-segment occlusion of the superior mesenteric vein, amenable to venous resection and reconstruction. The other patient was thought to have inflammatory changes discontiguous with the tumor surrounding the SMA, which resolved after therapy. TA >10 cm(2) (p = 0.03) and poor differentiation (p = 0.07) were associated with a worse survival duration; however, other factors, such as KPS and weight loss >10% and age did not influence OS.

CONCLUSION

Despite the selection of healthier patients to receive gemcitabine, there was a significantly higher severe toxicity rate than with 5-FU. The median and 1-year survivals were not significantly different with the use of concurrent gemcitabine; however, the tumors treated were significantly larger. Additionally, a small number of patients with minimal arterial involvement whose disease met our radiographic definition of unresectable disease had margin-negative resections after treatment with gemcitabine-based chemoradiation. These possible benefits and the high rate of severe toxicity define a very narrow therapeutic index for concurrent gemcitabine-based chemoradiation given by this schedule of administration.

Toxicity and efficacy of concurrent gemcitabine and radiotherapy for locally advanced pancreatic cancer

BACKGROUND

Gemcitabine and radiotherapy are a potent combination. A clinical assessment of the therapeutic ratio for locally advanced pancreatic cancer patients has not yet been reported.

AIM OF STUDY

To assess the toxicity, survival, and pattern of failure of locally advanced pancreatic cancer patients treated with concurrent gemcitabine-based chemoradiation. Patients and Methods. Between the dates of December 1996 and August 2000 51 patients with locally advanced unresectable adenocarcinoma of the pancreas were treated with concurrent gemcitabine and radiotherapy at MDACC. Patients received 250-500 mg/m2 of gemcitabine weekly x7 over 30 min and 30-33 Gy in 10-11 fractions over two weeks to the primary tumor and regional lymphatics. Severe toxicity was defined as admission > 5 d, mucosal ulceration, > 3 dose deletions of gemcitabine or toxicity resulting in surgical intervention or that resulted in death.

RESULTS

The median survival was 11 mo. Overall, 37 of 51 patients had objective evidence of local progression. The actuarial rate of local progression rate at 9 mo was 70%. The 9-mo distant metastasis rate was 52%. Tumors > or = 10 cm2 had worse local control, distant control, and overall survival. Six patients underwent pancreaticoduodenectomy after therapy. After review of the imaging, only four of these patients had minimal arterial involvement, one was incorrectly staged, and one had initial inflammatory change on CT that resolved. Twelve of 51 (24%) patients suffered severe acute toxicity, and 17 of 51 (33%) patients were admitted for supportive care.

CONCLUSION

Concurrent gemcitabine and radiotherapy can be a very difficult combination to administer safely. Our results do not suggest a prolongation of median survival for patients with localized pancreatic cancer treated with this therapy. It is possible that gemcitabine-based chemoradiation contributes to the margin-negative resectability of a small number of patients with minimal arterial involvement, but this benefit is obscured by the frequent toxicity encountered in most patients. Locally advanced pancreatic cancer patients should continue to be enrolled on prospective studies investigating novel combinations of cytotoxic and/or biologic agents with concurrent radiotherapy.

Sugar recovery and fermentability of hemicellulose hydrolysates from steam-exploded softwoods containing bark

The hemicellulose sugar recovery and ethanol production obtained from SO2-catalyzed steam explosion of a mixed white fir (70%) and ponderosa pine (30%) feedstock containing bark (9% dry weight/dry weight) was assessed. More than 90% of the available hemicellulose sugars could be recovered in the hydrolysate obtained after steam explosion at 195 degrees C, 2.38 min, and 3.91% SO2, with 59% of the original hemicellulose sugars detected in a monomeric form. Despite this high sugar recovery, this hydrolysate showed low ethanol yield (64% of theoretical yield) when fermented with a spent sulfite liquor-adapted strain of Saccharomyces cerevisiae. In contrast, most hydrolysates prepared at higher steam explosion severity showed comparable or higher ethanol yields. Furthermore, the hydrolysates prepared from bark-free feedstock showed better fermentability (87% of theoretical yield) despite containing higher concentration of known inhibitors. The ethanol yield from the hydrolysate prepared from a bark-containing wood sample could be improved to 81% by an extra stage acid hydrolysis (121 degrees C for 1 h in 3% sulfuric acid). This extra stage acid hydrolysis and steam explosion at higher severity conditions seem to improve the fermentability of the hydrolysates by transforming certain inhibitory compounds present in the hydrolysates prepared from the bark-containing feedstock and thus lowering their inhibitory effect on the yeast used for the ethanol fermentation.

Potential treatment for clubfeet based on growth factor blockade

Select soft tissues in clubfeet are contracted, resulting in stiffness. These contracted tissues share ultrastructural characteristics with palmar fibromatosis (Dupuytren contracture), in which the growth factors transforming growth factor-beta (TGF-beta) and platelet-derived growth factor (PDGF) are expressed and play a role in regulating cell behavior. More contracted tissue (medial side of the foot) and less contracted tissue (lateral side of the foot) from 20 clubfeet were studied using reverse transcription-polymerase chain reaction and western analysis for expression of TGF-beta and PDGF (along with collagen type I and type III). Cell cultures were established from the more contracted tissues to determine the effect of blockade of these factors with neutralizing antibodies on proliferation, chemotaxis, and collagen expression. Both growth factors were expressed at higher levels by the contracted tissues, and blockade led to decreased collagen expression, proliferation, and chemotaxis. Growth factor blockade has the potential to change the behavior of these cells in a way that would lessen the severity of the contractures, perhaps improving the outcome of clubfoot treatment.

Wegener's granulomatosis: the relationship between ocular and systemic disease

OBJECTIVE

Wegener's granulomatosis (WG) is an etiologically obscure entity with multiple systemic manifestations. Ocular involvement is present in up to 58% of patients with WG. We describe a series of patients with ocular manifestations of WG to evaluate the presence of ocular lesions in the setting of systemic WG and to determine the value of ocular inflammation in the diagnosis of WG.

METHODS

A computerized database was used to generate a list of patients cared for in the Ocular Immunology Service of the Massachusetts Eye and Ear Infirmary during the 10 year period 1988-98 with a diagnosis of Wegener's granulomatosis. A detailed chart review was undertaken to determine demographic characteristics, history, initial manifestation of WG, initial ocular presentation, biopsy results, laboratory testing results, treatment, total followup period, and final outcome.

RESULTS

Forty-seven patients diagnosed with WG were identified. Twenty-eight were women (59.6%), 19 were men (40.4%). The average age was 53 years (range 18-90). Patients were divided into 4 groups. Group I included 27 patients (57.4%) who had systemic disease first and who subsequently developed an ocular lesion. Group II included 3 patients (6.3%) who had ocular inflammation first and who then subsequently developed systemic manifestations of WG. Group III included 3 patients (6.3%) who presented due to ocular symptoms but, on initial evaluation by us, were found to have occult systemic manifestations consistent with WG or biopsy evidence of WG. Group IV included 14 patients (30%) with ocular lesions and no history or presence of systemic disease at their last followup visit.

CONCLUSION

Ocular inflammation can occur with or without obvious systemic manifestations of WG. It may represent the first sign of WG that enables the knowledgeable physician to diagnose this potentially lethal disease.