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T J Walsh

Publications and source records attributed to T J Walsh.

At least 73 records · Page 4Linked to original sources
PubMed2000

Esophageal candidiasis in pediatric acquired immunodeficiency syndrome: clinical manifestations and risk factors.

BACKGROUND: Little is known about the epidemiology and clinical features of esophageal candidiasis (EC) in pediatric AIDS. We therefore investigated the clinical presentation and risk factors of EC in a large prospectively monitored population of HIV-infected children at the National Cancer Institute. PATIENTS AND METHODS: We reviewed the records of all HIV-infected children (N = 448) followed between 1987 and 1995 for a history of esophageal candidiasis to characterize the epidemiology, clinical features, therapeutic interventions and outcome of esophageal candidiasis. To understand further the risk factors for EC in pediatric AIDS, we then performed a matched case-control analysis of 25 patients for whom control cases were available. RESULTS: There were 51 episodes of EC documented in 36 patients with 23 male and 13 female patients (0.2 to 17 years; median CD4, count 11/microl), representing a frequency of EC of 8.0%. Concurrent oropharyngeal candidiasis (OPC) was the most common clinical presentation of EC (94%); other signs and symptoms included odynophagia (80%), retrosternal pain (57%), fever (29%), nausea/vomiting (24%), drooling (12%), dehydration (12%), hoarseness (6%) and upper gastrointestinal bleeding (6%). The causative organism documented in 36 episodes (18 from OPC, 17 from endoscopic biopsy and 1 from autopsy) was Candida albicans in all cases. Patients received treatment for EC with amphotericin B (63%), fluconazole (29%), ketoconazole (4%) or itraconazole (1%). A clinical response was documented in all 45 evaluable episodes. In 6 other cases, EC was a final event without contributing to the cause of death. By a conditional logistic regression model for matched data, the best predictor of EC was the presence of prior OPC (P<0.0001), followed by CD4 count and CD4 percentage (P = 0.0002) and use of antibacterial antibiotics (P = 0.0013). The risks associated with low CD4 count were independent of that of prior OPC. CONCLUSION: EC in pediatric AIDS is a debilitating infection, which develops in the setting of prior OPC, low CD4 counts and previous antibiotics.

AIDS-Related Opportunistic Infections↗
PubMed2000

Distribution of lipid formulations of amphotericin B into bone marrow and fat tissue in rabbits.

The distribution of the three currently available lipid formulations of amphotericin B (AmB) into bone marrow and fat tissue was evaluated in noninfected rabbits. Groups of four animals each received either 1 mg of AmB deoxycholate (D-AmB) per kg of body weight per day or 5 mg of AmB colloidal dispersion, AmB lipid complex, or liposomal AmB per kg per day for seven doses. Plasma, bone marrow, fat, and liver were collected at autopsy, and AmB concentrations were determined by high-performance liquid chromatography. At the investigated dosages of 5 mg/kg/day, all AmB lipid formulations achieved at least fourfold-higher concentrations in bone marrow than did standard D-AmB at a dosage of 1 mg/kg/day. Concentrations in bone marrow were 62 to 76% of concurrent AmB concentrations in the liver. In contrast, all AmB formulations accumulated comparatively poorly in fat tissue. The results of this study show that high concentrations of AmB can be achieved in the bone marrow after administration of lipid formulations, suggesting their particular usefulness against disseminated fungal infections involving the bone marrow and against visceral leishmaniasis.

Adipocytes↗
PubMed2000

Effect of fluconazole on the pharmacokinetics of doxorubicin in nonhuman primates.

Antifungal prophylaxis in cancer patients who are undergoing chemotherapy is associated with prolonged neutropenia. We measured the effect of fluconazole on doxorubicin pharmacokinetics in nonhuman primates to determine if neutropenia is related to a pharmacokinetic interaction that delays the clearance of the chemotherapeutic agent. Fluconazole pretreatment had no effect on doxorubicin pharmacokinetics.

Animals↗
PubMed2000

Compartmental pharmacokinetics and tissue distribution of multilamellar liposomal nystatin in rabbits.

The plasma pharmacokinetics of multilamellar liposomal nystatin were studied in normal, catheterized rabbits after single and multiple daily intravenous administration of dosages of 2, 4, and 6 mg/kg of body weight, and drug levels in tissues were assessed after multiple dosing. Concentrations of liposomal nystatin were measured as those of nystatin by a validated high-performance liquid chromatography method, and plasma concentration data were fitted into a two-compartment open model. Across the investigated dosage range, liposomal nystatin demonstrated nonlinear kinetics with more than proportional increases in the AUC(0-24) and decreasing clearance, consistent with dose-dependent tissue distribution and/or a dose-dependent elimination process. After single-dose administration, the mean C(max) increased from 13.07 microg/ml at 2 mg/kg to 41.91 microg/ml at 6 mg/kg (P < 0.001); the AUC(0-24) changed from 11.65 to 67.44 microg. h/ml (P < 0.001), the V(d) changed from 0.205 to 0. 184 liters/kg (not significant), the CL(t) from 0.173 to 0.101 liters/kg. h (P < 0.05), and terminal half-life from 0.96 to 1.51 h (P < 0.05). There were no significant changes in pharmacokinetic parameters after multiple dosing over 14 days. Assessment of tissue concentrations of nystatin near peak plasma levels after multiple dosing over 15 days revealed preferential distribution to the lungs, liver, and spleen at that time point. Substantial levels were also found in the urine, raising the possibility that renal excretion may play a significant role in drug elimination. Liposomal nystatin administered to rabbits was well tolerated and displayed nonlinear pharmacokinetics, potentially therapeutic peak plasma concentrations, and substantial penetration into tissues. Pharmacokinetic parameters were very similar to those observed in patients, thus validating results derived from infection models in the rabbit and allowing inferences to be made about the treatment of invasive fungal infections in humans.

Animals↗
PubMed2000

Dose-dependent pharmacokinetics of amphotericin B lipid complex in rabbits.

Amphotericin B lipid complex (ABLC) was recently approved by the Food and Drug Administration for treatment of patients with invasive fungal infections who are intolerant of or refractory to conventional amphotericin B therapy. Little is known, however, about the pharmacokinetics of this new antifungal compound. We therefore investigated the pharmacokinetics of ABLC in comparison with those of conventional desoxycholate amphotericin B (DAmB) in rabbits. The pharmacokinetics of DAmB in a rabbit model were similar to those previously reported in humans. The pharmacokinetics of ABLC differed substantially from those of DAmB. Plasma amphotericin B levels following ABLC administration were 10 times lower than those following administration of an equal dosage of DAmB. The levels of ABLC in whole blood were approximately 40 times greater than those in plasma. The ABLC model differed from the DAmB model by (i) a dose- and time-dependent uptake and return between the plasma compartment and apparent cellular components of the blood-sediment compartment and (ii) time-dependent tissue uptake and return to plasma from serially connected compartments. Following infusion of ABLC, there was a nonlinear uptake into the apparent cellular components of the blood-sediment compartment. This uptake was related to the reciprocal of the integral of the total amount of drug infused (i.e., the more drug infused the greater the fractional uptake between 0.5 and 5 mg/kg of body weight for ABLC). The transfer of drug from plasma to the cellular components of the blood-sediment compartment resulted in initial uptake followed by rapid redistribution back to the plasma. The study describes a detailed model of the pharmacokinetics of ABLC and characterizes a potential role of the cellular components of the blood-sediment compartment in the distribution of this new antifungal compound in tissue.

Amphotericin B↗
PubMed2000

Acrophialophora fusispora brain abscess in a child with acute lymphoblastic leukemia: review of cases and taxonomy.

A 12-year-old girl with acute lymphoblastic leukemia was referred to King Faisal Specialist Hospital and Research Center. The diagnosis without central nervous system (CNS) involvement was confirmed on admission, and chemotherapy was initiated according to the Children Cancer Group (CCG) 1882 protocol for high-risk-group leukemia. During neutropenia amphotericin B (AMB) (1 mg/kg of body weight/day) was initiated for presumed fungal infection when a computed tomography (CT) scan of the chest revealed multiple nodular densities. After 3 weeks of AMB therapy, a follow-up chest CT revealed progression of the pulmonary nodules. The patient subsequently suffered a seizure, and a CT scan of the brain was consistent with infarction or hemorrhage. Because of progression of pulmonary lesions while receiving AMB, antifungal therapy was changed to liposomal AMB (LAMB) (6 mg/kg/day). Despite 26 days of LAMB, the patient continued to have intermittent fever, and CT and magnetic resonance imaging of the brain demonstrated findings consistent with a brain abscess. Aspiration of brain abscess was performed and the Gomori methenamine silver stain was positive for hyphal elements. Culture of this material grew Acrophialophora fusispora. Lung biopsy showed necrotizing fungal pneumonia with negative culture. The dosage of LAMB was increased, and itraconazole (ITRA) was added; subsequently LAMB was discontinued and therapy was continued with ITRA alone. The patient demonstrated clinical and radiological improvement. In vitro, the isolate was susceptible to low concentrations of AMB and ITRA. A. fusispora is a thermotolerant, fast-growing fungus with neurotropic potential. We report the first case of human infection involving the CNS. Acrophialophora resembles Paecilomyces but differs in having colonies that become dark and in the development of phialides along the sides or at the tips of echinulate brown conidiophores. Conidia are borne in long chains and are smooth or ornamented with fine-to-coarse echinulations, sometimes in spiral bands. The taxonomy of the genus Acrophialophora is reviewed, and Acrophialophora nainiana and Acrophialophora levis are considered as synonyms of A. fusispora.

Brain Abscess↗
PubMed2000

Emergence of resistance of Candida albicans to clotrimazole in human immunodeficiency virus-infected children: in vitro and clinical correlations.

Oropharyngeal candidiasis (OPC) is a common opportunistic infection in human immunodeficiency virus (HIV)-infected patients and other immunocompromised hosts. Clotrimazole troches are widely used in the treatment of mucosal candidiasis. However, little is known about the potential contribution of clotrimazole resistance to the development of refractory mucosal candidiasis. We therefore investigated the potential emergence of resistance to clotrimazole in a prospectively monitored HIV-infected pediatric population receiving this azole. Adapting the National Committee for Clinical Laboratory Standards M27-A reference method for broth antifungal susceptibility testing of yeasts to clotrimazole, we compared MICs in macrodilution and microdilution assays. We further analyzed the correlation between these in vitro findings and the clinical response to antifungal therapy. One isolate from each of 87 HIV-infected children was studied by the macrodilution and microdilution methods. Two inoculum sizes were tested by the macrodilution method (10(3) and 10(4) CFU/ml) in order to assess the effect of inoculum size on clotrimazole MICs. The same isolates also were tested using a noncolorimetric microdilution method. Clotrimazole concentrations ranged from 0.03 to 16 microg/ml. Readings were performed after incubation for 24 and 48 h at 35 degrees C. For 62 (71.2%) of 87 clinical isolates, the MICs were low (< or =0.06 microg/ml). The MIC for 90% of the strains tested was 0.5 microg/ml, and the highest MIC was 8 microg/ml. There was no significant difference between MICs at the two inoculum sizes. There was 89% agreement (+/-1 tube) between the microdilution method at 24 h and the macrodilution method at 48 h. If the MIC of clotrimazole for an isolate of C. albicans was > or =0.5 microg/ml, there was a significant risk (P < 0.001) of cross-resistance to other azoles: fluconazole, > or = 8 microg/ml (relative risk [RR] = 8.9); itraconazole, > or =1 microg/ml (RR = 10). Resistance to clotrimazole was highly associated with clinically overt failure of antifungal azole therapy. Six (40%) of 15 patients for whom the clotrimazole MIC was > or =0.5 microg/ml required amphotericin B for refractory mucosal candidiasis versus 4 (5.5%) of 72 for whom the MIC was <0.5 microg/ml (P = 0.001; 95% confidence interval = 2.3 to 22; RR = 7.2). These findings suggest that an interpretive breakpoint of 0.5 microg/ml may be useful in defining clotrimazole resistance in C. albicans. The clinical laboratory's ability to determine MICs of clotrimazole may help to distinguish microbiologic resistance from the other causes of refractory OPC, possibly reducing the usage of systemic antifungal agents. We conclude that resistance to clotrimazole develops in isolates of C. albicans from HIV-infected children, that cross-resistance to other azoles may develop concomitantly, and that this resistance correlates with refractory mucosal candidiasis.

AIDS-Related Opportunistic Infections↗
PubMed2000

Correlation between in vitro and in vivo antifungal activities in experimental fluconazole-resistant oropharyngeal and esophageal candidiasis.

Oropharyngeal and esophageal candidiasis (OPEC) is a frequent opportunistic mycosis in immunocompromised patients. Azole-resistant OPEC is a refractory form of this infection occurring particularly in human immunodeficiency virus (HIV)-infected patients. The procedures developed by the Antifungal Subcommittee of the National Committee for Clinical Laboratory Standards (NCCLS) are an important advance in standardization of in vitro antifungal susceptibility methodology. In order to further understand the relationship between NCCLS methodology and antifungal therapeutic response, we studied the potential correlation between in vitro susceptibility to fluconazole and in vivo response in a rabbit model of fluconazole-resistant OPEC. MICs of fluconazole were determined by NCCLS methods. Three fluconazole-susceptible (FS) (MIC, </=0.125 microgram/ml) and three fluconazole-resistant (FR) (MIC, >/=64 microgram/ml) isolates of Candida albicans from prospectively monitored HIV-infected children with OPEC were studied. FR isolates were recovered from children with severe OPEC refractory to fluconazole, and FS isolates were recovered from those with mucosal candidiasis responsive to fluconazole. Fluconazole at 2 mg/kg of body weight/day was administered to infected animals for 7 days. The concentrations of fluconazole in plasma were maintained above the MICs for FS isolates throughout the dosing interval. Fluconazole concentrations in the esophagus were greater than or equal to those in plasma. Rabbits infected with FS isolates and treated with fluconazole had significant reductions in oral mucosal quantitative cultures (P < 0.001) and tissue burden of C. albicans in tongue, soft palate, and esophagus (P < 0.001). In comparison, rabbits infected with FR isolates were unresponsive to fluconazole and had no reduction in oral mucosal quantitative cultures or tissue burden of C. albicans versus untreated controls. We conclude that there is a strong correlation between in vitro fluconazole susceptibility by NCCLS methods and in vivo response to fluconazole therapy of OPEC due to C. albicans.

Animals↗
PubMed2000

Pharmacoeconomic analysis of liposomal amphotericin B versus conventional amphotericin B in the empirical treatment of persistently febrile neutropenic patients.

PURPOSE: In a randomized, double-blind, comparative, multicenter trial, liposomal amphotericin B was equivalent to conventional amphotericin B for empirical antifungal therapy in febrile neutropenic patients, using a composite end point, but was more effective in reducing proven emergent fungal infections, infusion-related toxicities, and nephrotoxicity. The purpose of this study was to compare the pharmacoeconomics of liposomal versus conventional therapy. PATIENTS AND METHODS: Itemized hospital billing data were collected on 414 patients from 19 of the 32 centers that participated in the trial. Hospital length of stay and costs from the first dose of study medication to the time of hospital discharge were assessed. RESULTS: Hospital costs from the time of first dose to discharge were significantly higher for all patients who received liposomal amphotericin B ($48,962 v $43,183; P =.022). However, hospital costs were highly sensitive to the cost of study medication ($39,648 v $43,048 when drug costs were not included; P =.416). Using decision analysis models and sensitivity analyses to vary the cost of study medications and the risk of nephrotoxicity, the break-even points for the cost of liposomal therapy were calculated to range from $72 to $87 per 50 mg for all patients and $83 to $112 per 50 mg in allogeneic bone marrow transplant patients. CONCLUSION: The cost of liposomal amphotericin B and patient risk for developing nephrotoxicity play large roles in determining whether liposomal amphotericin B is cost-effective as first-line empirical therapy in persistently febrile neutropenic patients.

Adult↗
PubMed2000

New drugs and novel targets for treatment of invasive fungal infections in patients with cancer.

Invasive fungal infections have emerged as important causes of morbidity and mortality in profoundly immunocompromised patients with cancer. Current treatment strategies for these infections are limited by antifungal resistance, toxicity, drug interactions, and expense. In order to overcome these limitations, new antifungal compounds are being developed, which may improve our therapeutic armamentarium for prevention and treatment of invasive mycoses in high-risk patients with neoplastic diseases.

Anidulafungin↗
PubMed2000

Antifungal activity of splenic, liver and pulmonary macrophages against Candida albicans and effects of macrophage colony-stimulating factor.

Disseminated infections due to Candida albicans are frequently encountered in immunocompromised patients. We compared the antifungal activities of macrophages residing in spleen, liver and lungs of rabbits against blastoconidia and pseudohyphae of C. albicans. Splenic adherent cells (SAC), Kupffer cells (KC) and pulmonary alveolar macrophages (PAM) all ingested blastoconidia efficiently. SAC caused significantly more damage to unopsonized pseudohyphae compared with KC (P < 0.01) or PAM (P < 0.001). Incubation of SAC with 15 ng ml(-1) of recombinant human macrophage colony-stimulating factor (M-CSF) at 37 degrees C for 2 days significantly enhanced phagocytosis (P = 0.02) and killing (P = 0.05) of blastoconidia. In contrast, M-CSF had no effect on phagocytic activities of KC or PAM against blastoconidia or on damage caused by any of the macrophages to pseudohyphae of C. albicans. Thus, although all three resident macrophage types ingest blastoconidia efficiently, they differ in their capacity to cause damage to pseudohyphae and in their responsiveness to M-CSF for antifungal activation. M-CSF augments the capacity of SAC to ingest and kill blastoconidia and may therefore have a role in the treatment and prevention of hematogenously disseminated candidiasis.

Animals↗
PubMed2000

Preferential destruction of cerebellar Purkinje cells by OX7-saporin.

Saporin, a plant toxin derived from Saponaria officinalis, disrupts protein synthesis by inactivating the 60S portion of the ribosomal complex. OX7 is a mouse monoclonal antibody directed against the Thy-1.1 receptor that is differentially expressed on subpopulations of central nervous system neurons. Disulfide conjugation of OX7 to saporin permits delivery of saporin to target neurons. OX7-saporin was used to study the behavioral and morphological consequences of selective destruction of cerebellar Purkinje cells which abundantly express the Thy-1.1 antigen. Male Sprague-Dawley rats received bilateral intraventricular injections of 1- or 2 microg OX7-saporin or 8 microl artificial CSF. Rats were tested for behavioral changes 1 week before and 1, 2, and 8 weeks post-treatment. OX7-saporin treatment resulted in dose- and time-dependent changes in motor performance, activity, and negative geotaxis, but did not affect foot splay. Following behavioral testing, cerebellar sections were prepared for microscopic examination and the pattern of Purkinje cell loss was determined in anatomically matched sections. OX7-saporin induced dose-dependent death of Purkinje cells, particularly in the anterior and superior portions of cerebellar folia 1-6 and folium 9. Other brain regions appeared largely unaffected. Data suggest that intraventricular injection of rats with OX7-saporin is an effective model with which to examine the consequences of Purkinje cell destruction.

Animals↗
PubMed2000

Antifungal compounds: controversies, queries and conclusions.

A new session in this Congress was the development of a discussion panel regarding controversies and queries about the main topics of treatment and prophylaxis of severe systemic mycoses. Experts presenting each side of three controversial areas provided an interchange of ideas and clarified those areas where there remain substantial disagreements. Some common recommendations have been made, and some differences persist. The contents of this session are compiled in this paper. Due to the limitations of space, this paper presents the most relevant parts of each presentation. The large and up-to-date list of references should be useful to gain a better understanding of these subjects.

Amphotericin B↗
PubMed2000

New targets and delivery systems for antifungal therapy.

Development of new approaches for treatment of invasive fungal infections encompasses new delivery systems for approved and investigational compounds, as well as exploiting the cell membrane, cell wall and virulence factors as putative antifungal targets. Novel delivery systems consisting of cyclodextrins, cochleates, nanoparticles/nanospheres and long circulating ('stealth') liposomes, substantially modulate the pharmacokinetics of existing compounds, and may also be useful to enhance the delivery of antifungal agents to sites of infection. Further insights into the structure-activity relationship of the antifungal triazoles that target the biosynthesis of ergosterol in the fungal cell membrane have led to the development of highly potent broad spectrum agents, including posaconazole, ravuconazole and voriconazole. Similarly, a novel generation of cell-wall active semisynthetic echinocandin 1,3 beta-glucan inhibitors (caspofungin, FK463, and VER-002) has entered clinical development. These agents have potent and broad-spectrum activity against Candida spp, and potentially useful activity against Aspergillus spp. and Pneumocystis carinii. The ongoing convergence of the fields of molecular pathogenesis, antifungal pharmacology and vaccine development will afford the opportunity to develop novel targets to complement the existing antifungal armamentarium.

Antifungal Agents↗
PubMed2000

Antifungal peptides: Origin, activity, and therapeutic potential.

Antifungal peptides have been identified in a wide range of life forms which include plants, mammals, and microorganisms. Their structures are as varied as their antifungal properties. Semisynthetic and fully synthetic analogs have been developed from a few of these natural peptides that are superior to the parent compound. A few of these peptides hold promise in combating fungal infections and have entered clinical trials.

Journal Article↗
PubMed1999

High-performance liquid chromatographic determination of liposomal nystatin in plasma and tissues for pharmacokinetic and tissue distribution studies.

A reliable reversed-phase high-performance liquid chromatographic method was developed for the determination of liposomal nystatin in plasma. Nystatin is extracted by 1:2 (v/v) liquid-liquid extraction with methanol. Separation is achieved by HPLC after direct injection on a muBondapak C18 analytical column with a mobile phase composed of 10 mM sodium phosphate, 1 mM EDTA, 30% methanol and 30% acetonitrile adjusted to pH 6. Detection is by ultraviolet absorbance at 305 nm. Quantitation is based on the sum of the peak area concentration of the two major isomers of nystatin, which elute at 7.5-8.5 and 9.5-10.5 min. The assay was linear over the concentration range of 0.05 to 50 microg/ml. The lower limit of quantitation was 0.05 microg/ml, sufficient for investigating the plasma pharmacokinetics of liposomal nystatin in preclinical studies. Accuracies and intra- and inter-day precision showed good reproducibility. With minor modifications, this method also was used for assaying nystatin in various non-plasma body fluids and tissues.

Acetonitriles↗
PubMed1999

Liposomal amphotericin B for empirical therapy in patients with persistent fever and neutropenia. National Institute of Allergy and Infectious Diseases Mycoses Study Group.

BACKGROUND: In patients with persistent fever and neutropenia, amphotericin B is administered empirically for the early treatment and prevention of clinically occult invasive fungal infections. However, breakthrough fungal infections can develop despite treatment, and amphotericin B has substantial toxicity. METHODS: We conducted a randomized, double-blind, multicenter trial comparing liposomal amphotericin B with conventional amphotericin B as empirical antifungal therapy. RESULTS: The mean duration of therapy was 10.8 days for liposomal amphotericin B (343 patients) and 10.3 days for conventional amphotericin B (344 patients). The composite rates of successful treatment were similar (50 percent for liposomal amphotericin B and 49 percent for conventional amphotericin B) and were independent of the use of antifungal prophylaxis or colony-stimulating factors. The outcomes were similar with liposomal amphotericin B and conventional amphotericin B with respect to survival (93 percent and 90 percent, respectively), resolution of fever (58 percent and 58 percent), and discontinuation of the study drug because of toxic effects or lack of efficacy (14 percent and 19 percent). There were fewer proved breakthrough fungal infections among patients treated with liposomal amphotericin B (11 patients [3.2 percent]) than among those treated with conventional amphotericin B (27 patients [7.8 percent], P=0.009). With the liposomal preparation significantly fewer patients had infusion-related fever (17 percent vs. 44 percent), chills or rigors (18 percent vs. 54 percent), and other reactions, including hypotension, hypertension, and hypoxia. Nephrotoxic effects (defined by a serum creatinine level two times the upper limit of normal) were significantly less frequent among patients treated with liposomal amphotericin B (19 percent) than among those treated with conventional amphotericin B (34 percent, P<0.001). CONCLUSIONS: Liposomal amphotericin B is as effective as conventional amphotericin B for empirical antifungal therapy in patients with fever and neutropenia, and it is associated with fewer breakthrough fungal infections, less infusion-related toxicity, and less nephrotoxicity.

Adolescent↗