Novel terpenoid-type quinones isolated from Pycnanthus angolensis of potential utility in the treatment of type 2 diabetes

Using an ethnomedical-based drug discovery program, two previously unknown compounds (SP-18904 and SP-18905) from Pycnanthus angolensis were isolated that lower glucose concentrations in mouse models of type 2 diabetes. SP-18904 and SP-18905 are terpenoid-type quinones that significantly lowered plasma glucose concentration (p <.05) when given orally to either ob/ob or db/db mice, both of which are hyperglycemic and hyperinsulinemic. The antihyperglycemic actions of SP-18904 and SP-18905 were associated with significant decreases in plasma insulin concentrations (p <.05), suggesting that both compounds lowered glucose by enhancing insulin-mediated glucose uptake. This was supported by the insulin suppression test in ob/ob mice. Studies in hyperglycemic, insulin-deficient mice and in vitro experiments on 3T3-L1 adipocytes further supported this conclusion. As such, these two terpenoid-type quinones represent a new class of compounds of potential use in the treatment of type 2 diabetes.

Efficacy of nikkomycin Z in the treatment of murine histoplasmosis

Immune-competent ICR and BALB/c athymic (nude) mice were infected intravenously with Histoplasma capsulatum and treated with either fluconazole or nikkomycin Z or 5% dextrose (controls). In immune-competent ICR mice, fluconazole and nikkomycin Z both prolonged survival when given at 5 mg/kg of body weight twice daily. When administered in doses as low as 2.5 mg/kg twice daily, nikkomycin Z reduced fungal counts in both the spleen and liver. When both drugs were combined, there was no antagonism, and in combined therapy spleen and liver counts were reduced more than for either drug alone. However, nikkomycin Z had no effect on brain fungal burden. In nude mice fluconazole and nikkomycin Z had an additive effect in prolongation of survival and reduction of liver and spleen burden. Nikkomycin Z is well tolerated, is at least as effective as fluconazole, and may interact beneficially with fluconazole for treatment of murine histoplasmosis.

Comparison of topical administration of clotrimazole through surgically placed versus nonsurgically placed catheters for treatment of nasal aspergillosis in dogs: 60 cases (1990-1996)

OBJECTIVE

To examine the clinical response to topical administration of clotrimazole in dogs with nasal aspergillosis, to compare effect of surgically placed versus nonsurgically placed catheters used for administration on outcome, and to examine whether subjective scoring of computed tomographic images can predict outcome.

DESIGN

Retrospective case series.

ANIMALS

60 dogs with nasal aspergillosis.

PROCEDURE

Information including signalment, history, diagnostics, treatment method, and outcome was retrieved from medical records of dogs with nasal aspergillosis treated between 1990 and 1996 at the University of California School of Veterinary Medicine or cooperating referral practices. Final outcome was determined by telephone conversations with owners and referring veterinarians. Images obtained before treatment were subjectively assessed to develop an algorithm for predicting outcome.

RESULTS

Clotrimazole solution (1%) was infused during a 1-hour period via catheters surgically placed in the frontal sinus and nose (27 dogs) and via nonsurgically placed catheters in the nose (18). An additional 15 dogs received 2 to 4 infusions by either route. Topical administration of clotrimazole resulted in resolution of clinical disease in 65% of dogs after 1 treatment and 87% of dogs after one or more treatments. The scoring system correctly classified dogs with unfavorable and favorable responses 71 to 78% and 79 to 93% of the time, respectively.

CLINICAL IMPLICATIONS

Topical administration of clotrimazole, using either technique, was an effective treatment for nasal aspergillosis in dogs. Use of non-invasive intranasal infusion of clotrimazole eliminated the need for surgical trephination of frontal sinuses in many dogs and was associated with fewer complications.

Masoprocol (nordihydroguaiaretic acid): a new antihyperglycemic agent isolated from the creosote bush (Larrea tridentata)

An ethnomedically-driven approach was used to evaluate the ability of a pure compound isolated from the creosote bush (Larrea tridentata) to lower plasma glucose concentration in two mouse models of type 2 diabetes. The results indicated that plasma glucose concentration fell approximately 8 mmol/l in male C57BL/ks-db/db or C57BL/6J-ob/ob mice following the oral administration of masoprocol (nordihydroguaiaretic acid), a well known lipoxygenase inhibitor. The decline in plasma glucose concentration following masoprocol treatment in the mice was achieved without any change in plasma insulin concentration. In addition, oral glucose tolerance improved and the ability of insulin to lower plasma glucose concentrations was accentuated in masoprocol-treated db/db mice. These data raise the possibility that masoprocol, or other lipoxygenase inhibitors, represents a new approach to the pharmacological treatment of Type 2 diabetes.

Ethnobotanical-directed discovery of the antihyperglycemic properties of cryptolepine: its isolation from Cryptolepis sanguinolenta, synthesis, and in vitro and in vivo activities

Using an ethnobotanical approach in combination with in vivo-guided fractionation as a means for lead discovery, cryptolepine was isolated as an antihyperglycemic component of Cryptolepis sanguinolenta. Two syntheses of cryptolepine, including an unambiguous synthesis, are reported. The hydroiodide, hydrochloride, and hydrotrifluoromethanesulfonate (hydrotriflate) salts of cryptolepine were synthesized, and a comparison of their spectral properties and their in vitro activities in a 3T3-L1 glucose transport assay is made. Cryptolepine and its salt forms lower blood glucose in rodent models of type II diabetes. While a number of bioactivities have been reported for cryptolepine, this is the first report that cryptolepine possesses antihyperglycemic properties.

Compounds active against cell walls of medically important fungi

A number of substances that directly or indirectly affect the cell walls of fungi have been identified. Those that actively interfere with the synthesis or degradation of polysaccharide components share the property of being produced by soil microbes as secondary metabolites. Compounds specifically interfering with chitin or beta-glucan synthesis have proven effective in studies of preclinical models of mycoses, though they appear to have a restricted spectrum of coverage. Semisynthetic derivatives of some of the natural products have offered improvements in activity, toxicology, or pharmacokinetic behavior. Compounds which act on the cell wall indirectly or by a secondary mechanism of action, such as the azoles, act against diverse fungi but are usually fungistatic in nature. Overall, these compounds are attractive candidates for further development.

Positive interaction of nikkomycins and azoles against Candida albicans in vitro and in vivo

Nikkomycins X and Z (NZ), competitive inhibitors of fungal chitin synthetase, were combined with azoles in a series of in vitro checkerboard assays to test for synergism against Candida spp. All combinations of nikkomycins and azoles tested resulted in marked synergistic activity against an isolate of Candida albicans, with fractional inhibitory concentration indices ranging from 0.016 to 0.28. No synergistic effect was demonstrable with isolates of C. tropicalis, C. parapsilosis, or C. krusei, though results for the latter two were suggestive of an additive effect. In survival models of mice infected intravenously with C. albicans, NZ administered singly in doses ranging from 5 to 50 mg/kg of body weight twice a day was able to delay the onset of mortality but showed no dose-response effect. The combination of NZ and the azole R 3783 administered orally in a ratio of 8:1 to 40:1 or greater (wt/wt) enhanced survival better than did the drugs given individually, but this effect was less evident for combinations involving fluconazole. In short-term organ load assays with outbred mice infected intravenously with C. albicans, high ratios of NZ to R 3783 reduced the CFU per gram in kidneys more significantly than did the drugs individually. Statistically significant reductions were not seen for short-term fungal burden assays using combinations of NZ and fluconazole in outbred mice or in inbred mice more susceptible to candidiasis. In a model of rat vaginal candidiasis, the combination of NZ and R 3783 administered either orally or vaginally was more effective than the drugs used singly. Thus, under certain conditions, combination therapy with nikkomycin and select azoles may offer promise for an increased therapeutic effect in candidiasis.

Therapeutic effect of the triazole Bay R 3783 in mouse models of coccidioidomycosis, blastomycosis, and histoplasmosis

A new triazole, Bay R 3783, was compared with ketoconazole, itraconazole, and fluconazole, which were given via the alimentary tract at three dosages, and amphotericin B, which was given at 1 mg/kg intraperitoneally, in murine models of the systemic mycoses coccidioidomycosis, histoplasmosis, and blastomycosis. In a pulmonary coccidioidomycosis model, Bay R 3783, fluconazole, and itraconazole were essentially equally efficacious and more active than ketoconazole in protecting mice against death; but they were inferior to amphotericin B. In a short-term organ load experiment, Bay R 3783 and amphotericin B were equally effective and were more effective than the other drugs in reducing the amount of Coccidioides immitis in the lungs. Against meningocerebral coccidioidomycosis, Bay R 3783, itraconazole, and fluconazole at 25 mg/kg and amphotericin B prevented death only during therapy, with mortalities ensuing shortly thereafter. In mice with systemic histoplasmosis, Bay R 3783 and itraconazole at 25 mg/kg and amphotericin B prevented death in all mice through a 44-day observation period. Clearance of Histoplasma capsulatum from organs was similar in mice treated with Bay R 3783 and itraconazole; this clearance was greater than that in mice treated with ketoconazole and fluconazole but less than that in mice treated with amphotericin B. In mice with systemic blastomycosis, Bay R 3783 at 25 mg/kg yielded 90% survivors at 60 days, which was greater than that achieved with amphotericin B (60%) or itraconazole (30%). Clearance of Blastomyces dermatitidis from the lungs was greatest with Bay R 3783, followed by that with amphotericin B, itraconazole, fluconazole, and ketoconazole, in that order. Therefore, Bay R 3783 showed effectiveness comparable to or exceeding those of itraconazole and fluconazole and exceeding that of ketoconazole against these systemic mycoses in mice.

Use of DBA/2N mice in models of systemic candidiasis and pulmonary and systemic aspergillosis

Mouse models of systemic candidiasis and pulmonary and systemic aspergillosis were established by using DBA/2N mice, which are known to be deficient in the C5 component of complement. In experiments comparing lethality in the respective models in DBA/2N versus outbred CFW mice, results showed that the 50% lethal dose values for the DBA/2N mice were 10- to 1,000-fold lower than those for the outbred mice, depending on the experiment. Additionally, onset of death was somewhat delayed for the DBA/2N mice. In the case of the pulmonary aspergillosis model, administration of cortisone acetate was necessary to ensure lethality after intranasal infection, but only a single dose was necessary.

Evaluation of nikkomycins X and Z in murine models of coccidioidomycosis, histoplasmosis, and blastomycosis

Nikkomycins X and Z, competitive inhibitors of fungal chitin synthase, were evaluated as therapeutic agents in vitro and in mouse models of coccidioidomycosis, histoplasmosis, and blastomycosis. In vitro, the nikkomycins were found to be most effective against the highly chitinous, dimorphic fungi Coccidioides immitis and Blastomyces dermatitidis, were less effective against yeasts, and were virtually without effect on the filamentous fungus Aspergillus fumigatus. Additionally, by transmission electron microscopy, nikkomycin Z was highly disruptive to the cell wall and internal structure of the spherule-endospore phase of C. immitis in vitro. In vivo, nikkomycin Z was more effective than nikkomycin X, was also found to be superior on a milligram per milligram basis to the majority of azoles tested in the models of coccidioidomycosis and blastomycosis, and was moderately effective in histoplasmosis. A study of the pharmacokinetics in mice showed that nikkomycin Z was rapidly eliminated after intravenous infusion but that absorption after oral administration was sufficiently slow to allow inhibitory levels to persist for more than 2 h. Results of limited toxicology tests suggest that nikkomycin Z was well tolerated at the dosages employed.

Evaluation of Bay R 3783 in rodent models of superficial and systemic candidiasis, meningeal cryptococcosis, and pulmonary aspergillosis

The triazole Bay R 3783 was compared with fluconazole, itraconazole, ketoconazole, and amphotericin B in rodent models of superficial and systemic candidiasis, meningocerebral cryptococcosis, and pulmonary aspergillosis. Overall, Bay R 3783 was comparable or slightly superior to fluconazole and markedly superior to itraconazole and ketoconazole in both survival and short-term organ load experiments in models of candidiasis and cryptococcosis but was less effective than amphotericin B. Of the antifungal agents tested, only Bay R 3783 and itraconazole showed any efficacy in the model of pulmonary aspergillosis.

The use of flow cytometry to monitor chitin synthesis in regenerating protoplasts of Candida albicans

Flow cytometry was used to monitor chitin synthesis in regenerating protoplasts of the yeast Candida albicans. Comparisons of cells stained with Calcofluor White, a fluorochrome with known affinity for chitin, and cells incubated in the presence of N-[3H]-acetylglucosamine, the precursor substrate for chitin, showed a linear relationship between fluorescence and incorporation of label over time. Changes in both the fluorescence and light scatter of regenerating protoplasts treated with inhibitors of fungal chitin synthase were also quantitated by flow cytometry.

Treatment of experimental Pseudomonas aeruginosa pneumonia with a human IgM monoclonal antibody

A human IgM monoclonal antibody (MA-1C1) to Fisher immunotype 3 Pseudomonas aeruginosa lipopolysaccharide antigen was evaluated for in vivo activity in a guinea pig model of experimental pneumonia. Pharmacokinetics of MA-1C1 were compared in infected and noninfected animals. Intravenous bolus infusion of MA-1C1, 1 mg/kg, resulted in peak serum antibody concentrations of 3.8 +/- 0.08 and 3.7 +/- 0.05 micrograms/ml in infected and noninfected animals, respectively. Serum half-lives were 25 and 22 h in infected and noninfected groups. Treatment with a single intravenous infusion of MA-1C1 improved survival from pneumonia and was effective over a broad dose range (0.1-2.5 mg/kg). Cumulative survivals were 18 of 47 in the MA-1C1 group and 0 of 31 in controls (P less than .001). Treatment with MA-1C1 also resulted in fewer positive blood cultures 12 h after infection (P = .04). Although MA-1C1 penetrated into inflamed bronchial fluids, local concentrations were only 5% of the concentrations achieved in serum. Thus, MA-1C1 seems to provide significant therapeutic activity against experimental P. aeruginosa pneumonia by preventing dissemination of infection from the lung.

Microtiter method for MIC testing with spherule-endospore-phase Coccidioides immitis

A method was developed for susceptibility testing with spherule-endospore-phase Coccidioides immitis by using a microtiter format. Isolated endospores were used to inoculate wells containing modified Converse medium with various concentrations of azole or nikkomycin antifungal substances which then were sealed with an acetate film. The plate was incubated at 37 degrees C with shaking for 96 h, after which the control wells had visible turbidity and endpoints were discernible. Microscopic examination revealed that both control and treatment wells maintained cells predominantly in the spherule-endospore phase of growth.

Effect of cerulenin and sodium butyrate on chitin synthesis in Candida albicans

Experiments were conducted to gain insight concerning the mechanism(s) whereby cerulenin and sodium butyrate affect chitin synthesis in Candida albicans. In vitro studies with isolated membrane-bound chitin synthase from C. albicans, strain 4918, showed that neither agent affected the level of either unactivated or trypsin-activated enzyme activity. Subsequent studies utilizing protoplasts revealed that early in the cell wall regeneration process, cells treated with cerulenin or butyrate synthesized chitin at a rate equal to untreated controls, as measured by the incorporation of [3H]-N-acetylglucosamine (GlcNAc) into acid-alkali insoluble material. However, after 40 min of incubation, the incorporation of [3H]GlcNAc into chitin is reduced in cells treated with either agent. On the other hand, samples taken during the same time intervals and analyzed by flow cytometry suggested that the amount of chitin synthesis in treated and untreated cells was identical. A marked decrease in fluorescence was observed in similar experiments using polyoxin D, a direct inhibitor of chitin synthase activity. Experiments that measured uptake of [3H]GlcNAc into both whole cells and protoplasts demonstrated that cerulenin and butyrate had no effect on the transport of the chitin precursor.

Enhanced immune responses in mice treated with penicillin-tetracycline or trimethoprim-sulfamethoxazole when colonized intragastrically with Candida albicans

Immune consequences of gastrointestinal colonization of CD-1 and CBA/J mice with Candida albicans in the presence or absence of continuous antibiotic treatment with penicillin-tetracycline or trimethoprimsulfamethoxazole were investigated. Intubation with C. albicans in the absence of antibiotics resulted in the induction of low but detectable delayed-type hypersensitivity (DTH), demonstrable by footpad testing with a C. albicans wall glycoprotein (GP), and in the stimulation of a moderate level of protective immunity, demonstrable by intravenous (i.v.) challenge. DTH to a membrane extract, BEX, could not be detected in such animals. However, animals colonized in the presence of antibiotics and then inoculated cutaneously prior to being tested for DTH or protective immunity developed significantly enhanced levels of DTH to GP and BEX and were protected to an even greater extent than animals colonized in the absence of antibiotics who were not inoculated cutaneously. The priming effect of colonization, particularly with respect to the antigen GP, was also obvious from an enzyme-linked immunosorbent assay for GP-specific antibody with sera of mice surviving the i.v. challenge, in that GP-specific antibody was present in the highest titers in colonized animals that had been inoculated cutaneously prior to i.v. challenge. While the antibiotics promoted higher levels of colonization, as evidenced by stomach and fecal cultures of intubated mice, antibiotic administration was not necessary for the induction of C. albicans-specific responses. Moreover, contrary to reports in the literature, antibiotic administration had no adverse effect on the immune responses measured. Females were innately more resistant than males to i.v. challenge with C. albicans, but each sex was capable of developing protective immunity of equal intensity in response to colonization or immunization by cutaneous challenge.

[Prevention of gram-negative and gram-positive infections with 3 intravenous immunoglobulin preparations and therapy of experimental polymicrobial burn infection with intravenous Pseudomonas immunoglobulin G and ciprofloxacin in an animal model]

Three immunoglobulin preparations for intravenous infusion were compared in vivo to determine their relative protective capacity against several gram-negative and gram-positive pathogens. Polyglobin N is a conventional IgG concentrate. Psomaglobin N is identical in formulation to Polyglobin N but is prepared from the plasma of donors who have naturally high levels of antibody to lipopolysaccharide antigens of Pseudomonas aeruginosa. IgGMA is a conventional IgG concentrate containing 12% IgG and 16% IgA. In a murine model of burn wound sepsis the three IgG preparations were similarly protective against three or ten strains of P. aeruginosa. Psomaglobin N and Polyglobin N were significantly (p less than or equal to 0.015) more protective than IgGMA against six of ten and three of ten strains of P. aeruginosa, respectively. In a murine model of Streptococcus pneumoniae type 3 pneumonia, the three Ig preparations were similarly protective. IgGMA was significantly more protective (p less than or equal to 0.025) than Psomaglobin N and Polyglobin N against Salmonella typhimurium in murine peritonitis. However, the mean protective dose (PD50) of the two later preparations was less than or equal to 20 mg/kg body weight. In models of peritonitis both Psomaglobin N and Polyglobin N were more protective than IgGMA (p less than or equal to 0.004) against Haemophilus influenzae b, Klebsiella pneumoniae, Serratia marcescens 06:H3 and group B Streptococcus types 1b and 1c. Psomaglobin N and ciprofloxacin were employed to treat established polymicrobial murine burn wound sepsis resulting from contamination of the burn site with mixtures of P. aeruginosa and Staphylococcus aureus.(ABSTRACT TRUNCATED AT 250 WORDS)

[Prevention of gram-negative and gram-positive infections using 3 intravenous immunoglobulin preparations and therapy of experimental polymicrobial burn infection using intravenous Pseudomonas immunoglobulin G and ciprofloxacin in an animal model]

Three immunoglobulin preparations for intravenous infusion were compared in vivo to determine their relative protective capacity against several gram-negative and gram-positive pathogens. Polyglobin N is a conventional IgG concentrate. Psomaglobin N is identical in formulation to Polyglobin N but is prepared from the plasma of donors who have naturally high levels of antibody to lipopolysaccharide antigens of Pseudomonas aeruginosa. IgGMA is a conventional IgG concentrate containing 12% IgG and 16% IgA. In a murine model of burn wound sepsis the three IgG preparations were similarly protective against three or ten strains of P. aeruginosa. Psomaglobin N and Polyglobin N were significantly (p less than or equal to 0.015) more protective than IgG-MA against six of ten and three of ten strains of P. aeruginosa, respectively. In a murine model of Streptococcus pneumoniae type 3 pneumonia, the three Ig preparations were similarly protective. IgG-MA was significantly more protective (p less than or equal to 0.025) than Psomaglobin N and Polyglobin N against Salmonella typhimurium in murine peritonitis. However, the mean protective dose (PD50) of the two later preparations was less than or equal to 20 mg/kg body weight. In models of peritonitis both Psomaglobin N and Polyglobin N were more protective than IgGMA (p less than or equal to 0.004) against Haemophilus influenzae b, Klebsiella pneumoniae, Serratia marcescens 06:H3 and group B Streptococcus types 1b and 1c. Psomaglobin N and ciprofloxacin were employed to treat established polymicrobial murine burn wound sepsis resulting from contamination of the burn site with mixtures of P. aeruginosa and Staphylococcus aureus. Psomaglobin N or albumin was given once 16 h after challenge.(ABSTRACT TRUNCATED AT 250 WORDS)

Innate and acquired immune responses against Candida albicans in congenic B10.D2 mice with deficiency of the C5 complement component

Congenic mice, sufficient or deficient with respect to the C5 component of complement, were evaluated for their innate and acquired immune responses to Candida albicans. When unimmunized mice were challenged intravenously and sacrificed at intervals for cultural analyses of kidneys, it was clear that C5-sufficient mice were able to deal more effectively with C. albicans during the first week after challenge than C5-deficient mice. When immunized mice were challenged intravenously to assess the development of protective responses, an intact complement cascade appeared to contribute to the more rapid clearance of fungi during the first few weeks following challenge, but by the fourth week after challenge, the numbers of fungi had decreased significantly in both types of mice and were at levels which were not significantly different. No significant differences were detected in the development of delayed hypersensitivity or Candida-specific antibody between C5-sufficient and C5-deficient mice either. C5-deficient mice did have slightly elevated levels over the C5+ mice, but this may simply reflect the prolonged antigenic load during the first 3 weeks following intravenous challenge in both immune and nonimmune animals. The later-acting complement components, while appearing to contribute to the early inhibition of the growth of C. albicans in the nonimmune animal, had no adverse effect on the development of specific immune responses, in that delayed hypersensitive responses were equivalent between the two groups, antibody response was not significantly altered and the ultimate outcome of challenge in immunized animals was not affected.

A 96-well epifluorescence assay for rapid assessment of compounds inhibitory to Candida spp

A rapid method for the screening of potential antifungal compounds was developed. A variety of compounds were tested against regenerating protoplasts of Candida spp. in a microtiter format. The degree of cell wall formation was assessed by staining with Cellufluor (Polysciences, Inc., Warrington, Pa.), a fluorochrome with known affinity for chitin, followed by determination of fluorescence by using a Dynatech Microfluor reader (Dynatech Laboratories, Inc., Alexandria, Va.). Compounds with known activity against the cell wall or cytoplasmic membrane of fungi inhibited wall synthesis in a concentration-dependent fashion. Treatment with 5-fluorocytosine, however, resulted in no inhibition. In general, protoplasts of C. albicans regenerated more quickly and were more sensitive to the compounds tested than protoplasts of C. tropicalis and C. parapsilosis. While the described method is not specific for a given class of antifungal agents, it may prove useful for testing large numbers of compounds quickly.

Immunoglobulin G: potentiation of tobramycin and azlocillin in the treatment of Pseudomonas aeruginosa sepsis in neutropenic mice and neutralization of exotoxin A in vivo

Mice with cyclophosphamide-induced neutropenia were challenged with four immunotypes of Pseudomonas aeruginosa by contamination of a small dorsal surface wound. The infections were lethal; 100% of control animals (n = 80) treated only with albumin died. Administration of an immunoglobulin G intravenous preparation (IGIV) and/or therapy with tobramycin or azlocillin was begun 16 hr after challenge. Mortality among mice (n = 120) treated only with an antibiotic was 75.0%, while that among mice (n = 80) treated only with IGIV was 78.8%. Combination therapy with IGIV and an antibiotic (n = 120) resulted in mortality of 38.3%. The protection afforded by IGIV may have resulted in part from neutralization of exotoxin A, as mice treated with IGIV before challenge with exotoxin A were subject to lower mortality and had lower levels of serum aspartate and alanine aminotransferases than controls.

Synergistic action of nikkomycins X and Z with papulacandin B on whole cells and regenerating protoplasts of Candida albicans

Combinations of nikkomycin X (NX) or nikkomycin Z (NZ), known inhibitors of chitin synthesis in fungi, together with papulacandin B (PB), an inhibitor of beta-glucan synthesis, were tested for synergistic activity against four isolates of Candida albicans by using the broth microdilution checkerboard technique and a method to assess the regeneration of cell wall material in protoplasts. The construction of isobolograms from the data generated by the checkerboard determinations revealed a synergistic effect for the two classes of compounds against all strains. The combination of NX and PB was more effective than the combination of NZ and PB, perhaps reflecting the lower Ki value of NX. While the presence of NX and NZ reduced chitin synthesis, as determined by staining with calcofluor white and assaying with a microfluorimeter, cells treated with PB demonstrated an increased synthesis of chitin. Protoplast regeneration experiments using similar concentrations of the two classes of compounds resulted in comparable findings. The combination of NX and PB resulted in a greater inhibition of chitin synthesis than did equivalent combinations of NZ and PB. These data suggest that combinations of agents active against cell wall synthesis in fungi may prove more useful as chemotherapeutic agents than such compounds used singly.

Immunodeficient CBA/N mice respond effectively to Candida albicans

An immune defect in CBA/N mice diminishes their ability to respond adequately to certain well-defined antigens. Since the contribution of T and B cells to immunity in candidiasis has not been clearly defined, it was hoped that CBA/N mice might prove a useful model for the study of specific responses to Candida albicans. Therefore, immunodeficient CBA/N and immunocompetent CBA/J mice were immunized by two cutaneous inoculations of viable C. albicans B311 given 2 weeks apart and challenged iv 14 days after the second inoculation. Delayed-type hypersensitivity (DTH) was tested with a membrane-derived antigen (B-HEX) 7 days following the second inoculation, and lymphocyte stimulation with B-HEX, a cytoplasmic antigen (SCS), and mitogens was done at 12 days. Antibody to SCS was determined by ELISA 2 days after DTH testing and 28 days after iv challenge, at which time the animals were sacrificed for quantitative culture of kidneys and brains. Naive CBA/N mice were no more susceptible to challenge than CBA/J mice in that the mean log colony-forming units (CFU) were 3.79 and 5.48, respectively. Both strains responded to immunization by a similar reduction in CFU, a marked DTH response (e.g., reactions at 24 hr were 1.12 mm for CBA/N and 1.34 mm for CBA/J), and significant and similar quantities of antibody. The immune defect in CBA/N mice had no demonstrable effect on the development of immune responses to infection with C. albicans.

High-pressure liquid chromatographic assay of Bay n 7133 in human serum

A high-pressure liquid chromatographic method that includes a Sep-Pak (Waters Associates, Inc., Milford , Mass.) preparation of human serum was employed for the quantitative assay of Bay n 7133. Drug levels of 0.1 to 20 micrograms/ml could be detected. No interference from amphotericin B was found in the chromatographic analysis of Bay n 7133.

Control of systemic spread of Candida albicans with ketoconazole in the stomachs of mice treated with cytarabine

Attempts were made to colonize the gastrointestinal tract of outbred CD-1 mice with Candida albicans or Candida tropicalis before assessing the effects of cytarabine and ketoconazole on colonization. Stable populations of C. albicans but not C. tropicalis could be maintained in the stomachs of mice infected as adults if they were maintained on penicillin and tetracycline, or in untreated mice if the fungus was administered while they were infants. Treatment with cytarabine of mice colonized with C. albicans resulted in increased levels of yeast in the stomach, and small numbers of yeasts were recovered from the livers, kidneys, and spleens. Ketoconazole limited the multiplication of the yeast in the stomachs of colonized mice, although the effect was somewhat variable. Systemic spread of the fungus was essentially eliminated in animals receiving both ketoconazole and cytarabine, suggesting that ketoconazole may be an appropriate prophylactic agent for individuals undergoing therapy with cytarabine.

Inhibition of chitin synthesis in the cell wall of Coccidioides immitis by polyoxin D

The cell walls of both growth phases of Coccidioides immitis were studied by light and electron microscopy and biochemical procedures in an effort to assess the role of chitin in the fungus. Inhibition of normal chitin synthesis in the spherule by exposure to several concentrations of polyoxin D (PD) led to multiple morphological effects. Exposure of the mycelial phase to significantly higher levels of the compound had no morphological effect, as determined by autoradiography and light and electron microscopy. However, when equal masses of both morphological phases were treated with PD and pulsed with labeled N-acetylglucosamine, there was a greater relative (percent) reduction of incorporation of label in PD-treated mycelia compared with that of spherules. Nevertheless, the treated and untreated mycelia incorporated severalfold more counts than did corresponding spherules. The results suggest that chitin is important in maintaining the structural integrity of the spherule phase, but the role of chitin in the mycelial phase is less clear.

Immune responses to Candida albicans in genetically distinct mice

Mice from six genetically distinct strains were examined for their immune responses to Candida albicans in in vitro and in vivo assays, and naive mice and mice immunized with the fungus were challenged intravenously with three different doses of C. albicans to determine differences in susceptibility. Naive mice from the six groups showed substantial differences in resistance to challenge based on mortalities and quantitative cultures of kidneys, with mice from strains C57BL/6J and BALB/cByJ showing the most resistance; mice from strains A/J, C3H/HeJ, and CBA/J showing moderate susceptibility; and mice from strain DBA/2J showing the highest degree of susceptibility to challenge. Unimmunized mice from strains C57BL/6J and BALB/cByJ did not produce detectable levels of Candida-specific antibody by the end of the 28-day observation period when challenged intravenously, but the other strains did. Immunized mice showed a degree of protection to challenge, with all groups except mice from strain BALB/cByJ showing a reduction of two to three log units in the level of colonization in their kidneys and all strains producing significant levels of antibody. Additionally, the immunized mice of all strains developed substantial levels of delayed-type hypersensitivity and demonstrated nearly identical lymphocyte proliferative responses to Candida antigens. The results indicate that resistance to systemic candidiasis is dependent upon a combination of innate factors, predominately an intact complement system, and the acquisition of an immune response, most likely of a cell-mediated type. Additionally, the findings suggest that genetic control of acquired resistance to C. albicans may not be associated with the H-2 complex.

Mammary gland contamination as a means of establishing long-term gastrointestinal colonization of infant mice with Candida albicans

Infant outbred CD-1 mice were infected intragastrically with Candida albicans by inoculating the mammary glands of the lactating mothers with viable blastospores and allowing the infants to suckle. Levels of colonization were determined by quantitative cultures of stomachs and selected organs at various intervals up to 6 weeks after infection. The results demonstrate that a high percentage of infant mice can be colonized in this manner and that the colonization is of long duration. Although systemic spread of the yeast to other visceral organs did occur, the numbers of yeasts recovered were minimal.

Immunological relatedness among Candida albicans and other pathogenic Candida species

Membrane-mitochondrial (butanol-hot phosphate-buffered saline) and cytosol (soluble cytoplasmic substances) extracts from seven pathogenic species of Candida were used in in vivo and in vitro immunological assays to study antigenic similarities among the strains with respect to C. albicans. Mice were sensitized with C. albicans serotype A for footpad testing or to provide cells for lymphocyte stimulation assays, and guinea pigs were immunized with whole cells or butanol-hot phosphate-buffered saline extracts of C. albicans to obtain antisera for immunodiffusion assays. When extracts from each of the seven species were used in the assays, they consistently segregated, as determined by statistical or subjective analyses, into three groups. Extracts of C. albicans serotype A or B and C. stellatoidea were the most immunologically reactive in all assays, indicating close similarities between those two species, whereas extracts of C. tropicalis and C. parapsilosis elicited only moderate responses. Extracts from C. krusei, C. guilliermondii, and C. pseudotropicalis were hypo- or nonreactive in the assays, indicating a low level of antigenic relatedness to C. albicans.