PubMed Health⌕ Search

Biomedical subjects

J R Perfect

Publications and source records attributed to J R Perfect.

At least 19 recordsLinked to original sources
PubMed1992

Cloning the Cryptococcus neoformans TRP1 gene by complementation in Saccharomyces cerevisiae.

We have cloned the phosphoribosyl anthranilate isomerase (PRAI)-encoding gene (TRP1) of Cryptococcus neoformans by genetic complementation in Saccharomyces cerevisiae. Sequence analysis of this gene revealed it to be 939 bp in length, and without known promoter or termination sequences. Unlike some of the filamentous fungi, where PRAI enzymatic activity is controlled by a trifunctional gene product, the C. neoformans PRAI appears to be unifunctional. PRAI of C. neoformans exhibits 39% amino acid (aa) sequence identity compared to the S. cerevisiae counterpart. The TRP1 gene of C. neoformans maps to different size chromosomes in strains with different serotypes. The cloning of this gene for vector constructions, and the demonstration that S. cerevisiae can be used as a surrogate for C. neoformans gene expression, should help with the molecular studies of this significant fungal pathogen in our increasing immunocompromised population.

Aldose-Ketose Isomerases↗
PubMed1992

A nationwide survey of clinical laboratory methodologies for fungal infections.

Many hospitalized patients are at risk for fungal infections. In order to characterize present clinical laboratory experience and facilities for diagnosis and management of fungal infections, a nationwide survey of laboratory diagnostic methodologies was conducted. Data from calendar year 1988 were collected from 71 institutions (52 university teaching hospitals and 19 community hospitals) enrolled in the Drug Surveillance Network. Surveyed hospitals received 75,828 specimens for fungal culture in 1988, representing 18,705 positive cultures from 7373 patients. About 1.3% of patients admitted to teaching or community hospitals had positive fungal cultures, the most common isolates being Candida species. Yeast identification was most commonly performed by the germ tube test and carbohydrate assimilation testing. Dimorphic fungi were identified to the species level at 67% of hospitals. Cryptococcal antigen testing was available at all hospitals, and Candida serology testing was done at 55 institutions. A small number of hospitals performed antifungal drug concentration determinations for amphotericin B (n = 9), ketoconazole (n = 7) and flucytosine (n = 12). Fungal susceptibility testing was available at 77% of hospitals, either within the institution or at an external laboratory. Laboratory testing for diagnosis and management of fungal infections represents a major laboratory investment. Proficiency in this area, along with expert clinical advice, will be needed to advance therapy of patients complicated with fungal infections during the next decade.

Fungi↗
PubMed1992

Prophylactic intravenous amphotericin B in neutropenic autologous bone marrow transplant recipients.

This study assessed the efficacy, toxicity, and pharmacology of low-dose amphotericin B given prophylactically to patients (serum concentrations of 0.2-0.4 microgram/ml) undergoing bone marrow transplantation. Yeast isolates from patients' oropharyngeal areas had MICs of 0.1-0.2 microgram/ml, and none were amphotericin B resistant. The effect of low-dose amphotericin B on reducing the numbers of yeast colonizing the oropharyngeal area was significant (P less than .01). The average delay in switching to high-dose prophylactic amphotericin B was only 1 day; the decision to do so because of a perceived fungal infection occurred more frequently for the placebo group (P = .06). Fewer patients from the low-dose amphotericin B group (8.8%) than from the placebo group (14.3%) had fungi isolated from normally sterile body sites (P = .35). Infusion-related side effects but not systemic toxicities were significantly greater (P less than .001) in the amphotericin B group. The 6-week survival was greater in those receiving amphotericin B (P less than .03), but the improved survival could not be attributed to the prevention of fungal infections.

Adult↗
PubMed1992

Fungal scleritis after cataract surgery. Successful outcome using itraconazole.

We report the development of fungal scleritis in a 53-year-old man after uncomplicated cataract surgery. Histopathology and culture identified the organism as Aspergillus flavus. Clinically, the patient worsened on treatment with oral ketoconazole and topical amphotericin B with progression of multifocal scleral nodules and necrosis. Resolution of inflammation was achieved using oral itraconazole, a new triazole antifungal agent. The patient achieved 20/15-2 visual acuity and remains free of symptoms and signs for greater than 2 years after discontinuation of all treatment.

Administration, Oral↗
PubMed1990

The pharmacokinetics of BAY R3783 and its efficacy in the treatment of experimental cryptococcal meningitis.

We studied the pharmacokinetics and efficacy of BAY R3783, a new antifungal azole compound, in rabbits and compared it with fluconazole and itraconazole. BAY R3783 has at least two active metabolites, BAY U3624 and BAY U3625. We measured serum concentrations of all three compounds; the peak serum level for the parent compound was approximately two hours post dose. BAY R3783 and its metabolites also crossed the blood-CSF barrier; the mean CSF level of BAY R3783 was 30.5% of simultaneous serum levels. The in-vivo activity of the azoles was compared in a model of cryptococcal meningitis in immunosuppressed rabbits. BAY R3783, fluconazole and itraconazole all reduced yeast counts in the CSF with equal efficacy over ten days of therapy at 100 mg/day. In this model, BAY R3783 was effective in the treatment of cryptococcal meningitis.

Animals↗
PubMed1990

Production of the hexitol D-mannitol by Cryptococcus neoformans in vitro and in rabbits with experimental meningitis.

We studied the ability of Cryptococcus neoformans to produce the hexitol D-mannitol in vitro and in rabbits with experimental meningitis. Twelve of twelve human isolates of C. neoformans produced D-mannitol in yeast nitrogen base plus 1% glucose and released D-mannitol into the medium. In a pilot study, pooled cerebrospinal fluid (CSF) from cortisone-treated rabbits given 3 x 10(7) C. neoformans H99 intracisternally contained more D-mannitol (identified by gas chromatography and enzymatically) than CSF from normal controls or cortisone-untreated rabbits with self-limited meningitis. In a second experiment, cortisone-treated rabbits given C. neoformans intracisternally had significantly higher CSF D-mannitol concentrations than controls given cortisone alone at 4, 6, and 8 days after infection. Moreover, log10 CSF D-mannitol correlated well with log10 CSF CFU (r = 0.81) and log10 CSF cryptococcal antigen titers (r = 0.78). Lastly, the initial volume of distribution and elimination half-life of D-mannitol given intracisternally to normal rabbits suggested that D-mannitol was distributed in total CSF and was removed by CSF bulk flow. Thus, C. neoformans produces D-mannitol in vitro and in vivo, and D-mannitol is a quantitative marker for experimental cryptococcal meningitis. D-Mannitol produced by C. neoformans may also contribute to brain edema and interfere with phagocyte killing by scavenging hydroxyl radicals.

Animals↗
PubMed1990

Opsonic activity of cerebrospinal fluid in experimental cryptococcal meningitis.

The role of antibody in protection against infection with Cryptococcus neoformans is undefined. In this paper we describe the development of opsonic activity in the cerebrospinal fluid (CSF) of rabbits in response to cryptococcal meningitis. The opsonin appeared to be immunoglobulin G (IgG); the activity was heat stable, copurified with the IgG fraction during protein A separation, and could be absorbed by encapsulated cryptococci. Immunosuppression with cyclosporine could be administered to prevent or allow in vivo deposition of IgG on the polysaccharide capsule of yeast in the CSF. Both early and late cyclosporine regimens resulted in prolonged, severe meningeal infections corresponding to the complete absence of in vitro opsonic activity in the CSF. While the production of opsonic antibody is part of the successful host response against C. neoformans in the central nervous system of rabbits, the presence of specific immunoglobulin by itself is insufficient for complete protection.

Animals↗
PubMed1990

Metabolic fate of L-arginine in relation to microbiostatic capability of murine macrophages.

L-arginine is required for the fungistatic action of murine macrophages in vitro. To further investigate this requirement, L-arginine metabolism by macrophages was measured under conditions where fungistasis either succeeded or failed. Macrophage fungistasis correlated with metabolism of L-arginine to citrulline, nitrite, and nitrate. The metabolic rate was dependent on extracellular L-arginine concentration, reaching a maximum of 67 nmol nitrite/h per mg protein. It accounted for one-third of arginine consumed by fungistatic macrophages. Equimolar amounts of citrulline and total nitrite plus nitrate accumulated in medium. This was consistent with the hypothesis that one of the equivalent guanidino nitrogens of L-arginine was oxidized to both nitrite and nitrate leaving L-citrulline as the amino acid reaction product. The analogue, NG-mono-methyl-L-arginine, selectively inhibited nitrogen oxidation and it was shown previously that it inhibited fungistatic capability. Resident macrophages were not fungistatic and their nitrogen oxidation was low. Once macrophages began producing nitrite/nitrate, protein synthesis was not required during the next 8 h for either fungistasis or nitrogen oxidation. Two-thirds of L-arginine consumption was due to macrophage arginase yielding L-ornithine and urea, which accumulated in medium. This activity was dissociated from macrophage fungistasis. Nitrogen oxidation metabolism by macrophages is linked to a mechanism that inhibits proliferation of fungi. This may involve synthesis of an intermediate compound(s) that has antimicrobial properties.

Animals↗
PubMed1990

Antifungal therapy and its use in surgical treatment.

Modern surgery continues to make significant therapeutic advances, and a major component in the adjunctive care allowing these improved procedures is the successful use of broad-spectrum antibacterials. However, the widespread administration of potent antibacterials and the frequent use of a variety of catheters, along with an increase in the number of immune compromised patients requiring invasive procedures, have allowed deep-seated mycoses to become more common. Nosocomial fungal infections are frequent, particularly in the urinary tract and in the blood. This rise in identified fungal infections, along with frequent empiric treatment of suspected infection, has significantly increased amphotericin B therapy in surgical services in the last five years. While amphotericin B remains the standard for treatment of nosocomial mycoses, other antifungal agents are available (flucytosine, miconazole, ketoconazole and fluconazole). Despite experience with the older agents and the development of new agents, many questions remain concerning the use of currently available antifungal treatments in postsurgical patients. The following discussion attempts to summarize the magnitude of the problem, the difficulties with diagnosis and laboratory evaluations, the characteristics of the antifungal agents and particular problems with antifungal treatment in surgery.

Antifungal Agents↗
PubMed1989

Treatment of experimental cryptococcal meningitis and disseminated candidiasis with SCH39304.

We studied the pharmacokinetics and in vivo antifungal action of SCH39304, a new antifungal azole compound, in rabbits. It crossed the blood-cerebrospinal fluid barrier in the presence or absence of meningeal inflammation, reaching approximately 60% of the simultaneous concentrations in serum. In the treatment of experimental cryptococcal meningitis, SCH39304 was as effective as fluconazole in reducing yeast counts in the subarachnoid space. SCH39304 and fluconazole both were highly effective against candida endophthalmitis, sterilizing the vitreous humor and the choroid and retina. SCH39304 suppressed candida endocarditis and reduced yeast counts in the kidney at all doses tested. SCH39304 was effective in the treatment of experimental cryptococcal meningitis and disseminated candidiasis. Further investigations in humans are warranted.

Animals↗
PubMed1989

Treatment of experimental disseminated candidiasis with cilofungin.

The efficacy of cilofungin treatment of experimental disseminated candidiasis in rabbits was examined. Cilofungin treatment reduced yeast counts, especially in the kidney, with activity comparable to that of amphotericin B. The peak level of cilofungin in serum was measured at 5 min after administration of a single dose, with no drug detectable after 90 min.

Amphotericin B↗
PubMed1989

Separation of chromosomes of Cryptococcus neoformans by pulsed field gel electrophoresis.

Chromosomes from Cryptococcus neoformans, an encapsulated yeast pathogen, were separated by contour-clamped homogeneous field gel electrophoresis. Seven strains representing all four serotypes were studied. It was found that each strain had a unique, reproducible pattern of chromosome bands which could potentially be used for strain polymorphism studies. There were between 10 and 12 chromosomes in the strains studied, with an approximate genomic size of 15,000 to 17,000 kilobases. Chromosome separation also could be used to assign locations for cloned genes, and the ribosomal DNA genes were found on one of the larger C. neoformans chromosomes. The technique of electrophoretic karyotyping should be helpful for genetic and molecular investigations into the biology of C. neoformans.

Candida albicans↗
PubMed1989

Cryptococcosis.

Cryptococcosis emphasizes the importance of the host-parasite interaction. C. neoformans has developed factors to invade the host but generally requires host immune dysfunction to establish infection. Cryptococcal infection has increased as our immunocompromised pool of patients enlarges. Although many questions regarding management of cryptococcosis remain, it is a well-studied infection with excellent guidelines for diagnosis, treatment, and prognosis.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Mycobacterium avium-intracellulare complex infections in the acquired immunodeficiency syndrome.

This review examines an important bacterial infection in acquired immunodeficiency syndrome (AIDS). Despite occasional infections with bacteria such as Streptococcus pneumoniae, Haemophilus influenzae, Salmonella, and Nocardia in patients with AIDS, the primary problems of AIDS and invading bacterial infections center around mycobacteriosis. A unique feature of AIDS has been the common identification of disseminated infections with Mycobacterium avium-intracellulare. The following discussion examines our present understanding of this group of organisms and how they interact with the compromised host.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Cerebrospinal fluid macrophage response to experimental cryptococcal meningitis: relationship between in vivo and in vitro measurements of cytotoxicity.

The functional abilities of macrophages from cerebrospinal fluid (CSF) have so far been little studied. We examined the acquisition of activation characteristics by CSF macrophages during the course of experimental cryptococcal meningitis. CSF macrophages developed the ability for increased reactive oxidative intermediate (H2O2) production and tumor and fungal cytotoxicity. Despite having been activated, CSF macrophages could not inhibit the growth of Cryptococcus neoformans in vitro. Immunosuppression with cyclosporine, which eliminates the natural resistance of rabbits to cryptococcal meningitis, did not prevent or diminish H2O2 production by CSF macrophages but did reduce their tumoricidal activity. Activation of CSF macrophages appears to be an integral part of the central nervous system immune response to C. neoformans in this model, but alone is insufficient to eliminate C. neoformans from the central nervous system.

Animals↗