A Musculoskeletal Model Customized for Sagittal and Frontal Knee Kinematics with Improved Knee Joint Stability

Current lower limb musculoskeletal (MSK) models focus on sagittal plane kinematics. However, abnormal gait is typically associated with sagittal plane motions crossing into other planes, limiting the use of current MSK models. The purpose of this study was twofold, first, to extend the capability of a full-body MSK model from the literature to include frontal knee plane kinematics during healthy gait, and second, to propose and implement a realistic muscle discretization technique. Two MSK model constructs were derived - the first construct (Knee2_SM) allowed two degrees of freedom (sagittal and coronal) at the knee and the second construct (Knee2_MM) implemented multi-line elements for all the lower limb muscles in conjunction with two knee degrees of freedom. Motion analysis data of normal gait cycle from 10 healthy adults were used to compare joint kinematics, muscle moment arms, muscle forces, and muscle activations, between new constructs and the original model. Knee varus-valgus trajectories were estimated with the mean peak values ranging from 9.49° valgus to 1.57° varus. Knee2_MM predicted significant difference (p < 0.05) in moment arms and forces in those muscles responsible for medial-lateral stability of the knee. The simulated muscle activations generated by Knee2_MM model matched more closely to the experimental EMG when qualitatively compared. This study enhances the capability of sagittal plane full-body MSK model to incorporate knee varus-valgus motion while keeping the joint stability intact and improving muscle prediction.

Self-assembling N-(9-Fluorenylmethoxycarbonyl)-l-Phenylalanine hydrogel as novel drug carrier

Supramolecular hydrogel as a novel drug carrier was prepared from N-(9-Fluorenylmethoxycarbonyl) (Fmoc) modified l-phenylalanine. Its different properties like stability at different pH, temperature and rheology were evaluated in reference to salicylic acid (SA) as a model drug, entrapped in the supramolecular hydrogel network. The release behaviour of SA drug in supramolecular hydrogel was investigated by UV-vis spectroscopy. The influence of hydrogelator, pH values of the accepting media, temperature and concentration of SA drug on the release behaviour was investigated under static conditions. The results indicated that the release rate of SA in the supramolecular hydrogels was slightly retarded with an increase of the hydrogelator concentration. Also, the release rates of SA increased with an increase of temperature and its concentration. Furthermore, the release behaviour of SA was found to be different at various pH values in buffers. The study of the release kinetics indicated that the release behaviour of SA from the carrier was in accord with the Peppas model and the diffusion controlled mechanism involved in the Fickian model.

Chitosan silk-based three-dimensional scaffolds containing gentamicin-encapsulated calcium alginate beads for drug administration and blood compatibility

In the present study gentamicin was encapsulated within calcium alginate beads and incorporated into porous chitosan, gelatin, double-hybrid silk fibroin, chitosan/gelatin and double-hybrid silk fibroin/chitosan scaffolds. Physiochemical, morphological and biological properties of fabricated amenable model systems were evaluated, revealing hemocompatible nature of double-hybrid silk fibroin/chitosan and double-hybrid silk fibroin scaffolds of hemolysis %<5 and porosity >85%. Fourier transform infrared results confirmed the blend formation and scanning electron microscope images showed good interconnectivity. Double-hybrid silk fibroin/chitosan-blended scaffold shows higher compressive strength and compressive modulus than other fabricated scaffolds. A comparative drug release profile of fabricated scaffolds revealed that double-hybrid silk fibroin/chitosan scaffold is a pertinent model system because of its prolonged drug release, optimal hemocompatability and high compressive modulus.

Immune responses in histoplasmosis, a prototype of respiratory mycoses

The cellular and molecular mechanisms of host defenses to histoplasmosis, a prototype of respiratory fungal infections are described. Although, cell-mediated acquired immunity is considered as a hallmark of protective immunity to histoplasmosis, the recent findings provide mounting evidence on the importance of natural cellular immunity in host resistance to fungal infections. The natural immunity to Histoplasma capsulatum infection is primarily mediated by natural killer cells, endothelial cells and platelets but mechanisms of intercellular communication and their interactions with the pathogen are not clearly defined.

Laccase protects Cryptococcus neoformans from antifungal activity of alveolar macrophages

While laccase of Cryptococcus neoformans is implicated in the virulence of the organism, our recent studies showing absence of melanin in the infected mouse brain has led us to a search for alternative roles for laccase in cryptococcosis. We investigated the role of laccase in protection of C. neoformans against murine alveolar macrophage (AM)-mediated antifungal activity by using a pair of congenic laccase-positive (2E-TUC) and laccase-deficient (2E-TU) strains. The laccase-positive cells with laccase derepression were more resistant to the antifungal activity of AM than a laccase-deficient strain ([28.9 +/- 1.2]% versus [40.2 +/- 2.6]% killing). Addition of L-dopa to Cryptococcus to produce melanin in a laccase-positive strain resulted in a slight increase in protection of C. neoformans from the antifungal activity of macrophages ([25.4 +/- 3.4]% versus [28.9 +/- 1.2]% killing). Recombinant cryptococcal laccase exhibited iron oxidase activity in converting Fe(II) to Fe(III). Moreover, recombinant laccase inhibited killing of C. neoformans by hydroxyl radicals catalyzed by iron in a cell-free system. Addition of the hydroxyl radical scavenger mannitol or dimethyl sulfoxide to AMs prior to the introduction of cryptococcal cells decreased killing of both strains and reduced the difference in susceptibility between the laccase-positive and laccase-deficient strains. Furthermore, laccase-mediated protection from AM killing was inhibited by the addition of Fe(II), presumably by overcoming the effects of the iron oxidase activity of cryptococcal laccase. These results suggest that the iron oxidase activity of laccase may protect C. neoformans from macrophages by oxidation of phagosomal iron to Fe(III) with a resultant decrease in hydroxyl radical formation.

Interleukin-12 modulates the protective immune response in SCID mice infected with Histoplasma capsulatum

Infection with Histoplasma capsulatum results in a subclinical infection in immunocompetent hosts due to an effective cellular immune response. By contrast, immunodeficient individuals can have a severe disseminated and potentially fatal disease. In a previous study, it was demonstrated that normal mice infected intravenously with H. capsulatum and treated with interleukin-12 (IL-12) at the time of infection were protected from a fatal outcome. In this study, we examined the immunomodulatory effects of IL-12 on disseminated histoplasmosis in immunodeficient SCID mice. SCID mice infected with H. capsulatum and treated with IL-12 showed an increase in survival and a reduction in the colony counts of H. capsulatum in internal organs at 14 days after infection. The protective effect of IL-12 was abrogated if animals were also treated with a neutralizing antibody to gamma interferon (IFN-gamma). IL-12 treatment also resulted in an increase in mRNA expression and protein production for IFN-gamma, tumor necrosis factor alpha (TNF-alpha), and nitric oxide from spleen cells. When IL-12 was combined with amphotericin B (AmB) treatment, there was a significant increase in survival compared with either modality alone. Moreover, combined treatment resulted in an increase in both IFN-gamma and TNF-alpha production, as well as in a substantial reduction in H. capsulatum burden at 35 and 90 days postinfection. This study demonstrates that IL-12 modulates the protective immune response to histoplasmosis in SCID mice and also suggests that IL-12 in combination with AmB may be useful as a treatment for H. capsulatum in immunodeficient hosts.

Hormonal modulation of the vaginal bacterial flora in experimental polycystic ovarian disease

Rats exposed to constant light develop polycystic ovarian (PCO) disease with persistent estrus, representing an estrogen-dominant condition. Herein, we report that fluctuations seen in the vaginal microflora in cyclic rats were not observed in PCO rats with persistent estrus. The vaginal-cervical mucosa of PCO rats showed numerous adherent bacteria by scanning electron microscopy, similar to that seen in proestrus and estrus rats, but unlike the diestrus rats in which fewer organisms adhered to the mucosa. Administration of human chorionic gonadotropin induced ovulation in PCO rats, which was associated with a significant decrease in serum estradiol, an increase in progesterone, and a significant decrease in the estradiol/progesterone ratio compared with baseline values (P < 0.01). This also resulted in an influx of leukocytes in the vagina with a significant decrease in vaginal anaerobic as well as aerobic bacterial flora. These data demonstrate that loss of cyclic ovarian activity in PCO rats with persistent estrus causes increased bacterial colonization of the vaginal-cervical mucosa, and the ovarian hormones appear to modulate the colonization of bacteria in the lower genital tract.

IL-12 prevents mortality in mice infected with Histoplasma capsulatum through induction of IFN-gamma

Histoplasma capsulatum is a pathogenic fungus found in discrete geographic locations throughout the world. The fungus invades the reticuloendothelial organs such as the spleen and liver of immunocompetent hosts where it is usually controlled. However, in individuals with immune deficiency, histoplasmosis is a severe and potentially fatal disease. Resistance to this infection is due primarily to a cellular immune response mediated by T cells and macrophages. Moreover, IFN-gamma is critical in activating macrophages to kill the organism. Herein we study the regulation of cytokine induction in mice infected with H. capsulatum and the effects of IL-12 in the course of infection. Mice infected with H. capsulatum and treated with neutralizing Abs to IFN-gamma, TNF-alpha, or IL-12 experienced accelerated mortality, indicating that endogenous production of these cytokines plays an important role in response to infection. In contrast, mice treated with IL-12 or a neutralizing Ab to IL-4 at the initiation of infection had substantially diminished mortality. Moreover, mice infected and treated with IL-12 show a two- to threefold increase in the amount of IFN-gamma following in vitro stimulation with specific H. capsulatum Ag compared with the control infected mice. The protective effect of IL-12 could be abrogated if a neutralizing Ab to IFN-gamma was given at the same time, demonstrating that the role of IL-12 in protection was mediated by IFN-gamma. Additionally, infected mice treated with IL-12 had a severalfold decrease in the colony counts of H. capsulatum in spleen cells after 5 days of infection as compared with control animals. Lastly, spleen cells from infected animals treated with IL-12 showed a striking decrease in their proliferative response to mitogen or H. capsulatum Ag. Responses could be restored by adding inhibitors of IFN-gamma or of nitric oxide to the in vitro cultures. The above observations suggest that IL-12 may be useful in immunologic intervention against this opportunistic pathogen.

IL-12 prevents mortality in mice infected with Histoplasma capsulatum through induction of IFN-gamma

Histoplasma capsulatum is a pathogenic fungus found in discrete geographic locations throughout the world. The fungus invades the reticuloendothelial organs such as the spleen and liver of immunocompetent hosts where it is usually controlled. However, in individuals with immune deficiency, histoplasmosis is a severe and potentially fatal disease. Resistance to this infection is due primarily to a cellular immune response mediated by T cells and macrophages. Moreover, IFN-gamma is critical in activating macrophages to kill the organism. Herein we study the regulation of cytokine induction in mice infected with H. capsulatum and the effects of IL-12 in the course of infection. Mice infected with H. capsulatum and treated with neutralizing Abs to IFN-gamma, TNF-alpha, or IL-12 experienced accelerated mortality, indicating that endogenous production of these cytokines plays an important role in response to infection. In contrast, mice treated with IL-12 or a neutralizing Ab to IL-4 at the initiation of infection had substantially diminished mortality. Moreover, mice infected and treated with IL-12 show a two- to threefold increase in the amount of IFN-gamma following in vitro stimulation with specific H. capsulatum Ag compared with the control infected mice. The protective effect of IL-12 could be abrogated if a neutralizing Ab to IFN-gamma was given at the same time, demonstrating that the role of IL-12 in protection was mediated by IFN-gamma. Additionally, infected mice treated with IL-12 had a severalfold decrease in the colony counts of H. capsulatum in spleen cells after 5 days of infection as compared with control animals. Lastly, spleen cells from infected animals treated with IL-12 showed a striking decrease in their proliferative response to mitogen or H. capsulatum Ag. Responses could be restored by adding inhibitors of IFN-gamma or of nitric oxide to the in vitro cultures. The above observations suggest that IL-12 may be useful in immunologic intervention against this opportunistic pathogen.

Effect of subinhibitory concentrations of clindamycin and trospectomycin on the adherence of Staphylococcus epidermidis in an in vitro model of vascular catheter colonization

Septicemia, often due to Staphylococcus epidermidis, is a life-threatening complication associated with indwelling vascular catheters. An important factor in the development of such infections is glycocalix, or slime. An in vitro model that mimics intravenous delivery systems in humans was developed. It consisted of a modified Robbins device containing slices of silicone catheters in the removable ports, through which S. epidermidis diluted in 5% dextrose-normal saline with 10% heat-inactivated normal human serum was run, with and without clindamycin and trospectomycin. S. epidermidis was recovered from all catheters in the absence of antibiotics; no growth was detected with antibiotics. Scanning electron microscopy demonstrated significant reduction in glycocalix and no visible organisms with all concentrations except 0.5 micrograms/ml trospectomycin and 1 microgram/ml clindamycin; for those, a moderate amount of glycocalix and a few bacteria were seen. Thus, subinhibitory levels of trospectomycin and clindamycin may have a role in the prevention of microbial adherence to vascular catheters.

Correlation of Histoplasma capsulatum polysaccharide antigen with the severity of infection in murine histoplasmosis

We sought to determine if Histoplasma capsulatum polysaccharide antigen (HPA) levels correlate with the extent of infection in murine of histoplasmosis. Separate groups of mice were inoculated intratracheally with varying numbers of H. capsulatum yeast cells. After 1 week, HPA levels and fungal burden (quantitative culture of lung and spleen and histopathologic stain of lung) were determined in lung and spleen, and HPA levels in serum. HPA levels, cultures and histopathological stain results of lung and spleen tissue showed a direct correlation with increasing inoculum size. HPA levels in serum also correlated with the size of inoculum. H. capsulatum antigen in lung correlated with silver stain scores of lung tissue, (R = 0.948, P less than 0.001) and with quantitative culture scores of lung, (R = 0.929, P less than 0.001). HPA levels in spleen tissue also correlated with spleen culture scores, (R = 0.724, P less than 0.001). These results indicate that determination of HPA level in serum and tissue may be a useful test in evaluating the severity of diseases as well as efficacy of antifungal therapy in histoplasmosis.

Evaluation of an ELISA for the detection of anti-Histoplasma ribosomal and antihistoplasmin antibodies in histoplasmosis

We have developed an indirect sandwich enzyme-lined immunosorbent assay (ELISA) for the detection of antibodies to Histoplasma ribosomes and histoplasmin; we used this test for demonstration of these antibodies in sera from proven cases of histoplasmosis and other infections. Serum dilutions from five negative controls used in each experiment were normalized against 50 normal sera, and a factor of the mean absorbance was used to establish a positive reaction. Antiribosomal antibodies were detected in 97% of the known histoplasmosis patients with ELISA titers ranging from 1:100 to over 1:12,800. In contrast, antibodies to histoplasmin were detected in only 75% of these sera; titers ranged from 1:100 to 1:12,800. Cross-reactions with sera from other fungal infections (blastomycosis, coccidioidomycosis, paracoccidioidomycosis, cryptococcosis, candidiasis, and aspergillosis) were seen in 46% of the cases with ribosomes and 37% with histoplasmin. Fifty percent of the sera from tuberculosis patients gave positive reactions with ribosomes and 29% with histoplasmin. These results warrant further studies on the significance of antibodies to ribosomes and histoplasmin in immunity to histoplasmosis.

Pulmonary phaeohyphomycosis in a patient with hemoptysis

A 79-year-old retired schoolteacher had a history of bronchiectasis. She developed recurrent hemoptysis requiring multiple blood transfusions. Exophiala dermatitidis was cultured repeatedly from bronchial lavages. To our knowledge, this is the first documented case of isolated pulmonary phaeohyphomycosis due to E dermatitidis, and it was successfully treated with amphotericin B and 5-fluocytosine.

Production and characterization of murine monoclonal antibodies to Histoplasma capsulatum yeast cell antigens

Four monoclonal antibodies (MAbs) were produced by immunizing mice with a disrupted yeast cell homogenate of Histoplasma capsulatum. MAbs 1 and 2 reacted only with the yeast cell antigens of H. capsulatum and Blastomyces dermatitidis, whereas MAbs 3 and 4 showed broader cross-reactivity. MAb 3 cross-reacted with B. dermatitidis, Paracoccidioides brasiliensis, Sporothrix schenckii, and Candida albicans, and MAb 4 cross-reacted with B. dermatitidis, C. albicans, Coccidioides immitis, Aspergillus fumigatus, and Mycobacterium tuberculosis. All four MAbs exhibited unique specificity when reacted with three different strains of H. capsulatum (G217B, A811, and P-IN). MAb 1 belonged to the IgG2b subclass, MAb 3 belonged to the IgG1 subclass, and MAbs 2 and 4 belonged to the IgG3 subclass. MAbs 1, 2, and 3 formed bands in the Western immunoblot assay; the two dominant distinct bands had apparent molecular masses of 72 and 62 kilodaltons.

Significance of Histoplasma antigen in the cerebrospinal fluid of patients with meningitis

A radioimmunoassay was previously developed for detection of Histoplasma capsulatum antigen in the blood and urine of patients with disseminated histoplasmosis. In this investigation, cerebrospinal fluid (CSF) specimens from 14 episodes of Histoplasma meningitis occurring in 12 patients were tested by radioimmunoassay. Histoplasma capsulatum antigen was detected in the CSF of five patients. Cerebrospinal fluid cultures were positive for H capsulatum in three of these five patients. Antibodies to H capsulatum were found in nine of the 13 CSF specimens tested. The radioimmunoassay for Histoplasma antigen was also positive in the CSF in one of 11 patients with coccidioidal meningitis but not in 17 patients with cryptococcal meningitis. It was concluded that Histoplasma antigen is present in the CSF of some patients with histoplasmosis and chronic meningitis, but cross-reactions may occur in patients with coccidioidal meningitis.

Determination of viability of Histoplasma capsulatum yeast cells grown in vitro: comparison between dye and colony count methods

The viability of Histoplasma capsulatum yeast cells grown under different conditions was determined by dye tests with Eosin-Y and Janus Green B and by colony counts of cells plated on brain-heart infusion agar supplemented with histoplasma growth factor and bovine serum albumin (BHI-SAG). The test samples included cells grown on brain-heart infusion agar at 37 degrees C for 2-7 days, cells grown in glucose-cysteine broth medium for 1-31 days, and cells grown on brain-heart infusion agar for 3 days at 37 degrees C and then irradiated by ultraviolet light. The colony count indicated that the viability of the yeast cells grown on brain-heart infusion agar for 2 or 3 days varied between 68 and 100% depending on the isolates. The viability, however, dropped from 16 to 29% by day 7. The results of dye tests showed 78 to 99% dye-negative cells among the 2- and 3-day-old cultures while the number of dye-negative cells dropped to 32-36% on day 7. The colony count with the cells grown in the broth culture showed 100% viability until day 7 and dropped significantly by day 9. The results of dye tests showed no correlation with the colony count findings. The survival curve of ultraviolet-irradiated cells determined by colony count showed that irradiation at 180 erg mm-2 killed more than 50% of cells; fewer than 10% of cells survived 360 erg mm-2. The results of the dye test showed no difference between the irradiated and control populations.(ABSTRACT TRUNCATED AT 250 WORDS)

Diagnosis of disseminated histoplasmosis by detection of Histoplasma capsulatum antigen in serum and urine specimens

The diagnosis of Histoplasma capsulatum infection by serologic testing for the presence of antibodies is limited by a high rate of false positive and false negative results and by the requirement that the patient have a normal immune response. We have developed a radioimmunoassay for the detection of H. capsulatum antigen in urine and serum specimens. Antigenuria was noted in 20 of 22 episodes of disseminated histoplasmosis that occurred in 16 patients, in 6 of 32 patients with self-limited infection, in 2 of 32 patients with cavitary histoplasmosis, and in 4 of 8 patients with a sarcoid-like illness caused by H. capsulatum. The detection of antigen in urine was reproducible in 38 of 41 (93 percent) retests of specimens. H. capsulatum antigen was also detected in the serum during 11 of the 22 episodes of disseminated histoplasmosis, in none of the 12 episodes of other types of histoplasmosis in patients with antigenuria, in 1 of the 33 patients with histoplasmosis who lacked the urinary antigen, and in none of the 50 controls. Antigenemia and antigenuria decreased after initiation of antifungal therapy and recurred in patients who had a relapse. We conclude that this radioimmunoassay for H. capsulatum antigen represents a useful new method for the rapid diagnosis of disseminated histoplasmosis.

Protective effect of poly-2-vinylpyridine-N-oxide on susceptibility of silica-treated mice to experimental histoplasmosis

We have studied the ability of poly-2-vinylpyridine-N-oxide (PVNO), a lysosomal stabilizing agent, to abrogate the cytotoxic effects of silica on macrophages. Male C3H/HeN mice were pretreated with PVNO and inoculated intravenously with silica particles. At 24 h after silica injection, silica-treated and -untreated mice were challenged intravenously with varying doses of live yeast cells of Histoplasma capsulatum. All mice receiving silica died when challenged with 5 X 10(5) yeast cells of Histoplasma sp. compared with no deaths in PVNO-pretreated animals and 10% mortality in controls not receiving PVNO or silica. When animals were given 2.5 X 10(5) yeast cells (a sublethal dose), the protective effect of PVNO was seen by a reduction in splenomegaly and viable Histoplasma sp. present in the spleen. Furthermore, PVNO alone showed a significant protective effect (P less than 0.05) against a lethal challenge with Histoplasma sp. Prior treatment with PVNO also protected mouse peritoneal macrophages from the cytotoxic effects of silica particles in vitro. These results indicate that PVNO abrogates the cytotoxicity of silica particles on macrophages and also increases the resistance of mice to histoplasmosis.

Effect of silica on the susceptibility of mice to experimental histoplasmosis

The role of macrophages in the innate immunity of mice to histoplasmosis was investigated using silica, which selectively inactivates macrophages. Mice given silica IV 1 day prior to challenge with live yeast cells of Histoplasma capsulatum were more susceptible to infection than were untreated controls. This increased susceptibility to Histoplasma was observed when mice were given silica at 1, 14, and 21 days prior to infection but not at 3 and 7 days. Silica treated mice that survived 30 days after challenge with a sublethal dose of Histoplasma had 23 times more viable organisms in their spleens than in those of untreated controls. The blastogenic response of spleen cells to concanavalin A and phytohemagglutinin was unaffected at 12 hr after silica injection but was significantly depressed between 1 and 21 days. In contrast, silica treatment did not affect the blastogenic response of spleen cells to lipopolysaccharide. Silica particles were cytotoxic for mouse peritoneal macrophages but not to lymphocytes in vitro. These results indicate that macrophages play an essential role in natural immunity to histoplasmosis.

Bats in the belfry: an outbreak of histoplasmosis

The belfry and attic of a 100-year-old school building located in central Illinois were infested with a colony of big brown bats (Eptesicus fuscus). During the week of April 14, 1980, four workers disturbed the piles of bat droppings in the attic, causing dust to become airborne. Seven to 10 days later, all four workers developed symptoms and chest x-ray findings compatible with acute pulmonary histoplasmosis. Their sera had complement fixation (CF) titers of greater than or equal to 1:32 with fungal antigens and showed M and/or H bands by immunodiffusion tests. An additional 73 persons who had visited the building were also studied, leading to the finding of 16 additional cases of acute pulmonary histoplasmosis, identified on the basis of positive serologies and compatible symptoms. H. capsulatum was isolated from the sputum of one patient and from the soil beneath the hole in the building's eaves where the bats had been entering the attic. Cases were associated with exposure to the attic and with total hours of building exposure when compared with controls. The epidemic curve suggests that sporadic exposures occurred during the spring of 1980, with an epidemic occurring after the bat droppings were disturbed by the four workers.

Blastogenic responses of lymphocytes from mice immunized by sublethal infection with yeast cells of Histoplasma capsulatum

Blastogenic responses of spleen cells to histoplasmin and ribosomal antigens and to the mitogens concanavalin A. phytohemagglutinin, and lipopolysaccharide were studied in normal and immunized mice (10(5) live yeast cells of Histoplasma capsulatum given by the subcutaneous route). Cells (10(6) per well) were cultured with and without antigens and mitogens in microtiter plates with RPMI 1640-5% heat-inactivated normal mouse serum for 72 h at 37 degrees C. Cells were harvested after a 16- to 18-h pulse with 1 microCi of [3H]thymidine (6.7 Ci/mol), and thymidine incorporation was measured by scintillation counting. The initial blastogenic response to concanavalin A (54 X 10(3) cpm) was suppressed (P less than 0.001) from 4 to 14 days post-immunization and returned to control levels on day 21. The response to phytohemagglutinin was suppressed up to 21 days. Lipopolysaccharide responses, however, were affected to a lesser degree. Blastogenic responses to histoplasmin and H. capsulatum ribosomes were similar on day 0 in normal and immune lymphocytes, but by day 4 cells from immunized mice were more responsive (P less than 0.01). The maximum response to H. capsulatum antigens was detected on day 42 and was 9- to 16-fold higher than in controls. These results demonstrate in vitro responses of primed lymphocytes on exposure to H. capsulatum antigens and suppressed responses to mitogens during early stages of the immune response.

Immunogenicity of ribosomal preparations from Neisseria gonorrhoeae

Protection against gonococcal infection was obtained by immunization with ribosomal preparations from Neisseria gonorrhoeae. Ribosomes were isolated from disrupted cells by differential ultracentrifugation and treatment of the microsomal fraction with 0.25% sodium dodecyl sulfate. The isolated ribosomal preparations contained 55% ribonucleic acid, 39% protein, and 0.35% carbohydrate. The ribosomal preparations contained small amounts of endotoxin as determined by thiobarbituric acid- and lead acetate-sensitized mice assays. Guinea pigs immunized subcutaneously with ribosomal preparations were challenged intrachamberially with 10(7) colony-forming units of N. gonorrhoeae, and protection was assessed by clearance of the organism from subcutaneous chambers. The ribosomal preparations elicited significant protection, which was enhanced by incoporation of the immunogen into adjuvant. This protection was comparable to that obtained with whole cells. Treatment with proteolytic enzymes destroyed the protective effect of the ribosomal preparations, but ribonuclease had no measurable effect. Passive hemagglutination and immunodiffusion tests with sera from immunized animals demonstrated the presence of antibody to the ribosomal antigens. Results of adsorption of antiribosomal sera with enzyme-treated ribosomal preparations also indicated the protein nature of the immunogen. These results indicate that protein associated with the gonococcal ribosomal preparation is the major protective immunogen. The role of endotoxin contamination in the immunogenicity of gonococcal ribosomal preparations warrants further investigation.

Suppressive effect of 3-methylcholanthrene on phagocytic activity of mouse peritoneal macrophages for Torulopsis glabrata

The effect of 3-methylcholanthrene (MCA) on the phagocytic activity of mouse peritoneal macrophages for Torulopsis glabrata was investigated. Macrophages were maintained in glass scintillation vials or on cover slips in Leighton tubes with the use of Hanks' balanced salt solution plus 30% horse serum. Graded amounts of MCA were incorporated into the medium and the macrophages were parasitized with viable cells of T. glabrata. Macrophages from C3H mice, a strain highly susceptible to MCA carcinogenesis, were more prone to the suppressive effect of MCA than were the macrophages from CFW mice, a relatively resistant strain. Significant suppressive effect on phagocytosis of macrophages from C3H mice was observed with 5 micrograms MCA/ml, whereas up to 50 micrograms MCA/ml did not alter the phagocytic activity of CFW macrophages. However, 100 micrograms MCA/ml also suppressed the phagocytosis of CFW macrophages. Suppression in phagocytosis of C3H macrophages was observed after 6 hours' exposure to MCA, whereas a similar effect on CFW macrophages was seen after 12 hours. Treatment with 100 micrograms MCA/ml imparied the fungicidal activity of both C3H and CFW macrophages. These results indicate a correlation between the suppressive effect of MCA on macrophage activity and the strain susceptibility of mice to chemical carcinogenesis.

Significance of thymus-derived lymphocytes in immunity elicited by immunization with ribosomes or live yeast cells of Histoplasma capsulatum

The lymphoid cells responsible for protective immunity to histoplasmosis were characterized. Adoptive transfer of spleen and peritoneal cells treated with antiserum to theta-antigen from mice immunized with ribosomes or live yeast cells of Histoplasma capsulatum abrogated the ability of these cells to protect the syngeneic recipients, whereas treatment of lymphoid cells with antiserum to IgG did not affect the immunity. Prior removal of glass-adhering cells from spleen and peritoneal cell suspensions did not alter their protective activity. Treatment with mitomycin C, an antimitotic agent, ablated the capacity of immune lymphocytes to protect the syngeneic recipients. These results indicate that the immune spleen and peritoneal cells that confer immunity to histoplasmosis are thymus-dependent (T) lymphocytes and that their active proliferation in the recipients is necessary for expression of the protective immunity. Furthermore, the immunity elicited by immunization with histoplasma ribosomes and live yeast cells is mediated by a similar mechanism.

Characterization of the immunoprotective antigen of ribosomal preparations from Haemophilus influenzae

This investigation was designed to characterize the immunoprotective antigen of ribosomal preparations from Haemophilus influenzae. The ribosomes that elicited 80 to 90% protection contained 25% protein and 75% ribonucleic acid but did not contain any detectable hexoses. The immunodiffusion and hemagglutination inhibition tests also failed to demonstrate that the capsular material (polyribose phosphate) was in ribosomal preparations. Treatment of ribosomes with ribonuclease degraded 78% ribonucleic acid but did not affect the immunogenicity of such preparations. The proteolytic enzymes reduced the immunogenicity of ribosomes corresponding to the amount of protein degraded. The protection elicited by ribosomal protein extracted with 2-chloroethanol was comparable to that induced by intact ribosomes. In contrast, the low levels of protection observed by immunization with phenol-extracted ribonucleic acid were dependent on the amounts of contaminating protein. Finally, immunogenicity of ribosomal ribonucleic acid and protein was abrogated by treatment with proteolytic enzymes. These results clearly indicate that the protein associated with Haemophilus ribosomes is the major immunoprotective antigen.

Adoptive transfer of immunity from mice immunized with ribosomes or live yeast cells of Histoplasma capsulatum

This investigation was designed to compare the role of lymphoid cells and immune serum in protective immunity induced by immunization with ribosomes or live yeast cells of Histoplasma capsulatum. Spleen cells, peritoneal cells, and serum from C3H mice immunized with Histoplasma ribosomes or live cells were transferred intravenously to separate groups of syngeneic recipients. All recipients along with a set of immunized and control mice were challenged intravenously with 4 x 10(6) yeast cells of H. capsulatum, and protection was assessed. Immunization with ribosomes or live cells provided 90 to 100% protection. Mice receiving filtered spleen cells or peritoneal cells from donors immunnized with live cells showed 90 to 100% protection; 80 to 90% protection was observed for mice receiving cells from ribosome-immunized donors. In contrast, no evidence of protection was seen in mice receiving serum from either live-cell- or ribosome-immunized mice. Peritoneal cells were far more efficient than spleen cells in adoptive transfer of immunity. The adoptive immunity in recipients persisted for at least 3 weeks after transfer, the longest period tested in the present study. These results indicate that the immunity elicited by immunization with Histoplasma ribosomes or live cells is mediated by a cellular mechanism.

Immunoprotective activity of ribosomes from Haemophilus influenzae

Immunization with ribosomal preparations from Haemophilus influenzae type b elicited protective immunity in mice. Ribosomes from disrupted cells where isolated by differential centrifugation using sodium dodecyl sulfate. The washed ribosomes contained 25% protein and 75% ribonucleic acid and sedimented as a single peak on sucrose density gradient analysis with a sedimentation coefficient of 67S, using Escherichia coli ribosomes as a 70S marker. Immunodiffusion tests with antipolyribose phosphate serum showed that the ribosomes were free from capsular material. Mice immunized subcutaneously with ribosomes, with or without adjuvant, were challenged intraperitoneally with 100 to 1,000 mean lethal doses of H. influenzae type b suspended in gastric mucin. Significant protection was induced by ribosomes and was compared to that obtained after sublethal infection with live cells. The protection was greatly enhanced after incorporation of ribosomes into adjuvants. Maximum protection (90 to 95%) was observed at 1 to 2 weeks after immunization. Ribosomes from a nonencapsulated strain of H. influenzae were as immunogenic as those from the encapsulated strain, demonstrating that the capsular material is not responsible for immunogenicity of Haemophilus ribosomes.

Chemical composition of Oidiodendron kalrai

The chemical composition of yeast cells of Oidiodendron kalrai was analyzed and is expressed as percent dry weight. Cultures were grown in tryptone broth and in a liquid synthetic medium containing ammonium salts as a nitrogen source. After 48 h, carbohydrate levels were higher in the synthetic medium, but lipid levels were lower, Deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein contents did not differ significantly in the two media. The chemical components were also studied at different stages of growth. DNA remained relatively constant, but other components varied with the age of culture. The RNA was 6.6% at 18 h and declined rapidly to 5% by 24 h and remained constant, An initial protein content of 23% at 18 h increased rapidly to 37% by 48 h and gradually declined to 30% by day 10. The lipid content of 33% at 18 h decreased over the entire growth period to 10% by day 10. An initial carbohydrate level of 30% increased to a maximum of 54% by day 5 and then declined.

Ribonucleic acid synthesis in normal and immune macrophages after antigenic stimulus

Macrophage ribonucleic acid (RNA) synthesis is an important metabolic process intimately related to the function of these cells. Mouse peritoneal macrophage RNA was extracted with phenol in the presence of bentonite and electrophoresed on composite agarose-polyacrylamide gels. The pulse-chase technique was used to follow the precursor relationships in macrophage ribosomal RNA (rRNA) maturation. The rRNA species at 18S and 28S appeared at 15 and 45 min, respectively, after RNA synthesis was halted. Their appearance corresponded closely to decreases in the rRNA precursors at 45S, 36S, and 34S. Studies of RNA methylation aided in confirming the identity of these ribosomal species. Unmethylated RNA species appeared as messenger RNA between 5S and 15S, and at about 55S probably represented heterodisperse nuclear RNA. When normal macrophages were incubated with heat-killed Salmonella enteritidis, an acceleration in the maturation of RNA was observed. The accelerated maturation was indicated by the earlier appearance of 28S rRNA and the more rapid development of an equilibrium state, where further labeling did not change the RNA profile. In macrophage RNA from mice immunized with S. enteritidis, rRNA species appeared rapidly but did not accumulate to the same extent as observed for normal macrophages. Precursor rRNA and other RNA species developed as usual, suggesting specific degradation of mature rRNA. Such rRNA wastage could indicate a mechanism controlling ribosome assembly in the non-proliferating activated macrophage. The pattern of RNA synthesis in immune macrophages was essentially unchanged by the presence of heat-killed S. enteritidis in vitro.

Microbial flora of the larynx, trachea, and large intestine of the rat after long-term inhalation of 100 per cent oxygen

Effects of long-term inhalation of 100 per cent oxygen on the microbial flora of the rat larynx, trachea, and large intestine were studies. Rats were kept 14 days in an atmosphere of 100 per cent oxygen after being conditioned to high oxygen concentrations by exposure to three cycles of 100 per cent oxygen (two days) alternating with 40 percent oxygen (two days). Controls were kept under similar conditions in normal atmosphere. Rats were sacrificed, and at necropsy laryngotracheal swabs and fecal material from the large intestine were obtained and cultured for bacteria and fungi. Streptobacillus moniliformis, the predominant microorganism in the upper tracheas of controls, was not isolated from the oxygen-treated rats. Alpha-hemolytic streptococcus and Staphylococcus albus were present in control rats, but were found less frequently in rats exposed to oxygen. Pseudomonas and Proteus, infrequently isolated from controls, were predominant and sometimes the only microorganisms isolated from oxygen-treated rats. The data indicate that prolonged exposure of the rat to 100 per cent oxygen shifts the microbial flora in the upper respiratory tract from mainly gram-positive to mainly gram-negative bacteria. In contrast, there was no significant difference between the microbial flora in large intestines of control and oxygen-treated rats. The possibility that similar changes may occur in man should be considered when prolonged oxygen therapy is contemplated.

Purification of Oidiodendron kalrai proteases

Oidiodendron kalrai yeast-phase cells demonstrate proteolytic activity. Some of the proteolytic enzymes of the crude extract were purified by a combination of ammonium sulfate precipitation, Sephadex G-200, and diethylaminoethyl (DEAE) cellulose column chromatography. At least six proteins exhibiting a range of proteolytic activities could be identified by these procedures. Purity of the enzyme fractions obtained from the DEAE-cellulose columns was tested by running polyacrylamide gels.

Proteolytic activity of Oidiodendron kalrai

The physiochemical characteristics of the intracellular proteolytic enzymes of Oidiodendron kalari, a neuropathogenic fungus, were studied. The organism in the yeast phase was grown in a semisynthetic medium containing 1% tryptone, at 37 degrees C for 48 hr, on a gyrotory shaker. The crude extract was prepared by breaking the cells in a French pressure cell and the proteolytci activity was tested against biological substrates. The cell-free extract hydrolyzed casein, hemoglobin, lactalbumin, gelatin, elastin, collagen and purified rabbit renal basement membrane to various degrees. Optimal proteolytic activity was observed at pH 6 and at 32 degrees C. Calcium and EDTA did not affect the enzymatic activity; however, activity was partially inhibited by sulfhydryl-blocking agents and by heat-inactivated horse, calf, and human serum. The extract was totally inactivated by exposure to a temperature of 70 degrees C for 60 min. Storage at -76 degrees C or -15 degrees C for 6 months or at 4 degrees C for 4 weeks did not affect protease activity.

Comparative chemotherapeutic activity of amphotericin B and amphotericine B methy ester

The comparative efficacy of amphotericin B and amphotericin B methyl ester (AME) against experimental histoplasmosis, blastomycosis, cryptococcosis, and candidosis in mice was assessed by determining the effect of daily intraperitoneal therapy on 21-day survival and persistence of organisms in internal organs. AME, like amphotericin B, was effective against each of the experimental infections, but the efficacy was lower than the parent compound. For Histoplasma and Blastomyces infections the mean effective dose (ED(50)) of amphotericin B was 0.3 mg/kg, whereas the corresponding values for AME, respectively, were 2.4 and 2.8 mg/kg. For Cryptococcus infection the ED(50) for amphotericin B was 0.2 mg/kg compared with 2.0 mg/kg for AME. The ED(50) of amphotericin B for Candida infection was lower than 0.05 mg/kg and the value of AME was between 0.5 to 0.05 mg/kg. The colony counts from internal organs of the surviving animals after the therapeutic regimens were compatible with the data on survival.

Comparative in vitro antifungal activity of amphotericin B and amphotericin B methyl ester

The in vitro antifungal activity of amphotericin B methyl ester (AME), a water-soluble derivative of amphotericin B, was compared to that of the parent compound against a variety of pathogenic and potentially pathogenic fungi. AME has a significant antifungal activity, but the activity of AME was slightly lower than that of amphotericin B. Among the yeast-like organisms, only the yeast cells of Sporothrix schenckii were more resistant than others to both antibiotics, with a minimal fungicidal concentration of 5 to 10 mug/ml. The yeast cells of other fungi were killed at concentrations of 1 mug or less of either antibiotic per ml. The filamentous forms of S. schenckii and Oidiodendron kalrai were more resistant than the filamentous forms of other dimorphic fungi to both drugs. The minimal fungicidal concentration for S. schenckii was 10 mug/ml and for O. kalrai, 50 mug/ml. The dermatophytes, phycomycetes, and dematacious and other potentially pathogenic fungi were inhibited fairly well by both drugs, but up to 50 mug/ml was required for fungicidal action. The water solubility and wide spectrum of antifungal activity of AME warrant evaluation of its chemotherapeutic activity against experimental fungal infections.

Immunogenicity of Ribosomal Preparations from Yeast Cells of Histoplasma capsulatum

Protective immunity was elicited by immunization of mice with ribosomal preparations from yeast cells of Histoplasma capsulatum . Ribosomes from disrupted cells were isolated by differential centrifugation using sodium dodecyl sulfate. These preparations contained 55% protein and 45% ribonucleic acid and sedimented as a single peak with a sedimentation coefficient of 77 S on sucrose density gradient analysis. Mice immunized subcutaneously with ribosomes, with or without adjuvant, were challenged intravenously with 8 × 10 6 yeast cells of H. capsulatum . Significant protection was induced by ribosomes and was greatly enhanced by adjuvants. Protection measured by 30-day survival compared favorably with the immunoprotection assessed by absence of lung lesions and negative spleen cultures. Treatment of ribosomes with ribonuclease before immunization reduced protection by 85%, whereas trypsin and Pronase reduced the protection by 50 to 55%. These findings indicate that both intact ribosomal ribonucleic acid and protein are necessary for maximal immunogenicity of Histoplasma ribosomes.