Donor-derived Coccidioides immitis fungemia in solid organ transplant recipients

We report disseminated coccidioidomycosis in 3 transplant recipients from a donor in an endemic area found to have unrecognized meningeal coccidioidomycosis. All 3 transplant recipients presented within 3 weeks of receipt of their organ. Only 1 organ recipient survived the acute presentation of coccidioidomycosis. Serologic testing for Coccidioides immitis infection should be considered for organ donors residing in endemic areas.

Predictors of poor clinical outcome of cryptococcal meningitis in HIV-infected patients

The aim of this study was to identify baseline prognostic factors for poor clinical outcome of HIV-associated cryptococcal meningitis. We conducted a trial in Thailand and the USA comparing low- and high-dose concomitant use of amphotericin B and fluconazole for HIV-associated cryptococcal meningitis to amphotericin B followed by fluconazole. Subjects who were either alive and cerebrospinal fluid (CSF) culture-positive or dead were considered to have a poor outcome. At day 14, baseline characteristics associated with poor outcome included: low weight, high CSF cryptococcal antigen (CrAg) titre and low CSF white blood cell (WBC) count. At day 70, the associated baseline characteristics included: CSF CrAg titre >1:1024 and low Karnofsky performance status. Overall, consistent with published findings, low weight, high CSF CrAg titre and low CSF WBC counts at baseline were predictors for poor clinical outcome. In addition, we found that low Karnofsky performance status was predictive of poor outcome. Prompt management with appropriate antifungal therapy for this particular group of patients may improve the outcomes.

Characterization of a Lignite Ash from the Metc Gasifier II. Scanning Electron Microscopy

Lignite coal ash produced in a stirred, fixed-bed gasifier at the Morgantown Energy Technology Center (METC) has been studied by scanning electron microscopy using both morphologic and chemical analyses. Detailed chemical analyses of phases, grains, and traverses across grains illustrate the heterogeneous nature of the ash. These data support the concept that most of the ash was formed by partial melting and subsequent crystallization and agglomeration.

Monitoring and impact of fluconazole serum and cerebrospinal fluid concentration in HIV-associated cryptococcal meningitis-infected patients

OBJECTIVES

The aim of the present study was to assess fluconazole pharmacokinetic measures in serum and cerebrospinal fluid (CSF); and the correlation of these measures with clinical outcomes of invasive fungal infections.

METHODS

A randomized trial was conducted in HIV-infected patients receiving three different regimens of fluconazole plus amphotericin B (AmB) for the treatment of cryptococcal meningitis. Regimens included fluconazole 400 mg/day+AmB (AmB+Fluc400) or fluconazole 800 mg/day+AmB (AmB+Fluc800) (14 days followed by fluconazole alone at the randomized dose for 56 days); or AmB alone for 14 days followed by fluconazole 400 mg/day for 56 days. Serum (at 24 h after dosing) and CSF samples were taken at baseline and days 14 and 70 (serum only) for fluconazole measurement, using gas-liquid chromatography.

RESULTS

Sixty-four treated patients had fluconazole measurements: 11 in the AmB group, 12 in the AmB+Fluc400 group and 41 in the AmB+Fluc800 group. Day 14 serum concentration geometric means were 24.7 mg/L for AmB+Fluc400 and 37.0 mg/L for AmB+Fluc800. Correspondingly, CSF concentration geometric means were 25.1 mg/L and 32.7 mg/L. Day 14 Serum and CSF concentrations were highly correlated with AmB+Fluc800 (P<0.001, r=0.873) and AmB+Fluc400 (P=0.005, r=0.943). Increased serum area under the curve (AUC) appears to be associated with decreased mortality at day 70 (P=0.061, odds ratio=2.19) as well as with increased study composite endpoint success at days 42 and 70 (P=0.081, odds ratio=2.25 and 0.058, 2.89, respectively).

CONCLUSION

High fluconazole dosage (800 mg/day) for the treatment of HIV-associated cryptococcal meningitis was associated with high serum and CSF fluconazole concentration. Overall, high serum and CSF concentration appear to be associated with increased survival and primary composite endpoint success.

Multicenter retrospective development and validation of a clinical prediction rule for nosocomial invasive candidiasis in the intensive care setting

The study presented here was performed in order to create a rule that identifies subjects at high risk for invasive candidiasis in the intensive care setting. Retrospective review and statistical modelling were carried out on 2,890 patients who stayed at least 4 days in nine hospitals in the USA and Brazil; the overall incidence of invasive candidiasis in this group was 3% (88 cases). The best performing rule was as follows: Any systemic antibiotic (days 1-3) OR presence of a central venous catheter (days 1-3) AND at least TWO of the following-total parenteral nutrition (days 1-3), any dialysis (days 1-3), any major surgery (days -7-0), pancreatitis (days -7-0), any use of steroids (days -7-3), or use of other immunosuppressive agents (days -7-0). The rate of invasive candidiasis among patients meeting the rule was 9.9%, capturing 34% of cases in the units, with the following performance: relative risk 4.36, sensitivity 0.34, specificity 0.90, positive predictive value 0.01, and negative predictive value 0.97. The rule may identify patients at high risk of invasive candidiasis.

In vitro-clinical correlations for amphotericin B susceptibility in AIDS-associated cryptococcal meningitis

Reliable measures of antifungal drug susceptibility are needed. We tested the susceptibility of Cryptococcus neoformans from patients treated with amphotericin B. In vitro susceptibility employed a modified broth macrodilution method. We demonstrate a strong correlation between the quantitative measures of in vitro amphotericin B susceptibility and the quantitative response observed in patients.

Cryptococcosis in human immunodeficiency virus-negative patients in the era of effective azole therapy

We conducted a case study of human immunodeficiency virus (HIV)-negative patients with cryptococcosis at 15 United States medical centers from 1990 through 1996 to understand the demographics, therapeutic approach, and factors associated with poor prognosis in this population. Of 306 patients with cryptococcosis, there were 109 with pulmonary involvement, 157 with central nervous system (CNS) involvement, and 40 with involvement at other sites. Seventy-nine percent had a significant underlying condition. Patients with pulmonary disease were usually treated initially with fluconazole (63%); patients with CNS disease generally received amphotericin B (92%). Fluconazole was administered to approximately two-thirds of patients with CNS disease for consolidation therapy. Therapy was successful for 74% of patients. Significant predictors of mortality in multivariate analysis included age > or =60 years, hematologic malignancy, and organ failure. Overall mortality was 30%, and mortality attributable to cryptococcosis was 12%. Cryptococcosis continues to be an important infection in HIV-negative patients and is associated with substantial overall and cause-specific mortality.

Aspartic peptide hydrolases in Salmonella enterica serovar typhimurium

Two well-characterized enzymes in Salmonella enterica serovar Typhimurium and Escherichia coli are able to hydrolyze N-terminal aspartyl (Asp) dipeptides: peptidase B, a broad-specificity aminopeptidase, and peptidase E, an Asp-specific dipeptidase. A serovar Typhimurium strain lacking both of these enzymes, however, can still utilize most N-terminal Asp dipeptides as sources of amino acids, and extracts of such a strain contain additional enzymatic activities able to hydrolyze Asp dipeptides. Here we report two such activities from extracts of pepB pepE mutant strains of serovar Typhimurium identified by their ability to hydrolyze Asp-Leu. Although each of these activities hydrolyzes Asp-Leu at a measurable rate, the preferred substrates for both are N-terminal isoAsp peptides. One of the activities is a previously characterized isoAsp dipeptidase from E. coli, the product of the iadA gene. The other is the product of the serovar Typhimurium homolog of E. coli ybiK, a gene of previously unknown function. This gene product is a member of the N-terminal nucleophile structural family of amidohydrolases. Like most other members of this family, the mature enzyme is generated from a precursor protein by proteolytic cleavage and the active enzyme is a heterotetramer. Based on its ability to hydrolyze an N-terminal isoAsp tripeptide as well as isoAsp dipeptides, the enzyme appears to be an isoAsp aminopeptidase, and we propose that the gene encoding it be designated iaaA (isoAsp aminopeptidase). A strain lacking both IadA and IaaA in addition to peptidase B and peptidase E has been constructed. This strain utilizes Asp-Leu as a leucine source, and extracts of this strain contain at least one additional, as-yet-uncharacterized, peptidase able to cleave Asp dipeptides.

Conserved residues Ser(16) and His(20) and their relative positioning are essential for TonB activity, cross-linking of TonB with ExbB, and the ability of TonB to respond to proton motive force

The cytoplasmic membrane protein TonB couples the proton electrochemical potential of the cytoplasmic membrane to transport events at the outer membrane of Gram-negative bacteria. The amino-terminal signal anchor of TonB and its interaction with the cytoplasmic membrane protein ExbB are essential to this process. The TonB signal anchor is predicted to form an alpha-helix, with a conserved face comprised of residues Ser(16), His(20), Leu(27), and Ser(31). Deletion of either Ser(16) or His(20) or of individual intervening but not flanking residues rendered TonB inactive and unable to assume a proton motive force-dependent conformation. In vivo formaldehyde cross-linking experiments revealed that the ability of this subset of mutants to form a characteristic heterodimer with ExbB was greatly diminished. Replacement of residues 17-19 by three consecutive alanines produced a wild type TonB allele, indicating that the intervening residues (Val, Cys, and Ile) contributed only to spacing. These data indicated that the spatial relationship of Ser(16) to His(20) was essential to function and suggested that the motif HXXXS defines the minimal requirement for the coupling of TonB to the cytoplasmic membrane electrochemical gradient. Deletion of Trp(11) resulted in a TonB that remained active yet was unable to cross-link with ExbB. Because Trp(11) was demonstrably not involved in the actual cross-linking, these results suggest that the TonB/ExbB interaction detected by cross-linking occurred at a step in the energy transduction cycle distinct from the coupling of TonB to the electrochemical gradient.

Comparison of oral fluconazole and itraconazole for progressive, nonmeningeal coccidioidomycosis. A randomized, double-blind trial. Mycoses Study Group

BACKGROUND

In previous open-label noncomparative clinical trials, both fluconazole and itraconazole were effective therapy for progressive forms of coccidioidomycosis.

OBJECTIVE

To determine whether fluconazole or itraconazole is superior for treatment of nonmeningeal progressive coccidioidal infections.

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING

7 treatment centers in California, Arizona, and Texas.

PATIENTS

198 patients with chronic pulmonary, soft tissue, or skeletal coccidioidal infections.

INTERVENTION

Oral fluconazole, 400 mg/d, or itraconazole, 200 mg twice daily.

MEASUREMENTS

After 4, 8, and 12 months, a predefined scoring system was used to assess severity of infection. Findings were compared with those at baseline.

RESULTS

Overall, 50% of patients (47 of 94) and 63% of patients (61 of 97) responded to 8 months of treatment with fluconazole and itraconazole, respectively (difference, 13 percentage points [95% CI, -2 to 28 percentage points]; P = 0.08). Patients with skeletal infections responded twice as frequently to itraconazole as to fluconazole. By 12 months, 57% of patients had responded to fluconazole and 72% had responded to itraconazole (difference, 15 percentage points [CI, 0.003 to 30 percentage points]; P = 0.05). Soft tissue disease was associated with increased likelihood of response, as in previous studies. Azole drug was detected in serum specimens from all but 3 patients; however, drug concentrations were not helpful in predicting outcome. Relapse rates after discontinuation of therapy did not differ significantly between groups (28% after fluconazole treatment and 18% after itraconazole treatment). Both drugs were well tolerated.

CONCLUSIONS

Neither fluconazole nor itraconazole showed statistically superior efficacy in nonmeningeal coccidioidomycosis, although there is a trend toward slightly greater efficacy with itraconazole at the doses studied.

Practice guidelines for the management of cryptococcal disease. Infectious Diseases Society of America

An 8-person subcommittee of the National Institute of Allergy and Infectious Diseases (NIAID) Mycoses Study Group evaluated available data on the treatment of cryptococcal disease. Opinion regarding optimal treatment was based on personal experience and information in the literature. The relative strength of each recommendation was graded according to the type and degree of evidence available to support the recommendation, in keeping with previously published guidelines by the Infectious Diseases Society of America (IDSA). The panel conferred in person (on 2 occasions), by conference call, and through written reviews of each draft of the manuscript. The choice of treatment for disease caused by Cryptococcus neoformans depends on both the anatomic sites of involvement and the host's immune status. For immunocompetent hosts with isolated pulmonary disease, careful observation may be warranted; in the case of symptomatic infection, indicated treatment is fluconazole, 200-400 mg/day for 36 months. For those individuals with non-CNS-isolated cryptococcemia, a positive serum cryptococcal antigen titer >1:8, or urinary tract or cutaneous disease, recommended treatment is oral azole therapy (fluconazole) for 36 months. In each case, careful assessment of the CNS is required to rule out occult meningitis. For those individuals who are unable to tolerate fluconazole, itraconazole (200-400 mg/day for 6-12 months) is an acceptable alternative. For patients with more severe disease, treatment with amphotericin B (0.5-1 mg/kg/d) may be necessary for 6-10 weeks. For otherwise healthy hosts with CNS disease, standard therapy consists of amphotericin B, 0.7-1 mg/kg/d, plus flucytosine, 100 mg/kg/d, for 6-10 weeks. An alternative to this regimen is amphotericin B (0.7-1 mg/kg/d) plus 5-flucytosine (100 mg/kg/d) for 2 weeks, followed by fluconazole (400 mg/day) for a minimum of 10 weeks. Fluconazole "consolidation" therapy may be continued for as along as 6-12 months, depending on the clinical status of the patient. HIV-negative, immunocompromised hosts should be treated in the same fashion as those with CNS disease, regardless of the site of involvement. Cryptococcal disease that develops in patients with HIV infection always warrants therapy. For those patients with HIV who present with isolated pulmonary or urinary tract disease, fluconazole at 200-400 mg/d is indicated. Although the ultimate impact from highly active antiretroviral therapy (HAART) is currently unclear, it is recommended that all HIV-infected individuals continue maintenance therapy for life. Among those individuals who are unable to tolerate fluconazole, itraconazole (200-400 mg/d) is an acceptable alternative. For patients with more severe disease, a combination of fluconazole (400 mg/d) plus flucytosine (100-150 mg/d) may be used for 10 weeks, followed by fluconazole maintenance therapy. Among patients with HIV infection and cryptococcal meningitis, induction therapy with amphotericin B (0.7-1 mg/kg/d) plus flucytosine (100 mg/kg/d for 2 weeks) followed by fluconazole (400 mg/d) for a minimum of 10 weeks is the treatment of choice. After 10 weeks of therapy, the fluconazole dosage may be reduced to 200 mg/d, depending on the patient's clinical status. Fluconazole should be continued for life. An alternative regimen for AIDS-associated cryptococcal meningitis is amphotericin B (0.7-1 mg/kg/d) plus 5-flucytosine (100 mg/kg/d) for 6-10 weeks, followed by fluconazole maintenance therapy. Induction therapy beginning with an azole alone is generally discouraged. Lipid formulations of amphotericin B can be substituted for amphotericin B for patients whose renal function is impaired. Fluconazole (400-800 mg/d) plus flucytosine (100-150 mg/kg/d) for 6 weeks is an alternative to the use of amphotericin B, although toxicity with this regimen is high. In all cases of cryptococcal meningitis, careful attention to the management of intracranial pressure is imperative to assure optimal c

Protonmotive force, ExbB and ligand-bound FepA drive conformational changes in TonB

TonB couples the cytoplasmic membrane protonmotive force (pmf) to active transport across the outer membrane, potentially through a series of conformational changes. Previous studies of a TonB transmembrane domain mutant (TonB-delta V17) and its phenotypical suppressor (ExbB-A39E) suggested that TonB is conformationally sensitive. Here, two new mutations of the conserved TonB transmembrane domain SHLS motif were isolated, TonB-S16L and -H20Y, as were two new suppressors, ExbB-V35E and -V36D. Each suppressor ExbB restored at least partial function to the TonB mutants, although TonB-delta V17, for which both the conserved motif and the register of the predicted transmembrane domain alpha-helix are affected, was the most refractory. As demonstrated previously, TonB can undergo at least one conformational change, provided both ExbB and a functional TonB transmembrane domain are present. Here, we show that this conformational change reflects the ability of TonB to respond to the cytoplasmic membrane proton gradient, and occurs in proportion to the level of TonB activity attained by mutant-suppressor pairs. The phenotype of TonB-delta V17 was more complex than the -S16L and -H20Y mutations, in that, beyond the inability to be energized efficiently, it was also conditionally unstable. This second defect was evident only after suppression by the ExbB mutants, which allow transmembrane domain mutants to be energized, and presented as the rapid turnover of TonB-delta V17. Importantly, this degradation was dependent upon the presence of a TonB-dependent ligand, suggesting that TonB conformation also changes following the energy transduction event. Together, these observations support a dynamic model of energy transduction in which TonB cycles through a set of conformations that differ in potential energy, with a transition to a higher energy state driven by pmf and a transition to a lower energy state accompanying release of stored potential energy to an outer membrane receptor.

Early mycological treatment failure in AIDS-associated cryptococcal meningitis

Cryptococcal meningitis causes significant morbidity and mortality in persons with AIDS. Of 236 AIDS patients treated with amphotericin B plus flucytosine, 29 (12%) died within 2 weeks and 62 (26%) died before 10 weeks. Just 129 (55%) of 236 patients were alive with negative cerebrospinal fluid (CSF) cultures at 10 weeks. Multivariate analyses identified that titer of cryptococcal antigen in CSF, serum albumin level, and CD4 cell count, together with dose of amphotericin B, had the strongest joint association with failure to achieve negative CSF cultures by day 14. Among patients with similar CSF cryptococcal antigen titers, CD4 cell counts, and serum albumin levels, the odds of failure at week 10 for those without negative CSF cultures by day 14 was five times that for those with negative CSF cultures by day 14 (odds ratio, 5.0; 95% confidence interval, 2.2-10.9). Prognosis is dismal for patients with AIDS-related cryptococcal meningitis. Multivariate analyses identified three components that, along with initial treatment, have the strongest joint association with early outcome. Clearly, more effective initial therapy and patient management strategies that address immune function and nutritional status are needed to improve outcomes of this disease.

Amphotericin B colloidal dispersion combined with flucytosine with or without fluconazole for treatment of murine cryptococcal meningitis

Studies with animals and in vitro studies have demonstrated that flucytosine plus amphotericin B or fluconazole has significantly improved mycologic activity against meningitis caused by Cryptococcus neoformans compared to the activity of amphotericin B or fluconazole used alone. However, few doses have been tested in combination. This study evaluated the antifungal efficacy of amphotericin B colloidal dispersion (ABCD) combined with flucytosine with and without fluconazole in a murine model of cryptococcal meningitis. The following dosages were tested: ABCD at 0 to 12.5 mg/kg of body weight given intravenously 3 days/week, flucytosine at 0 to 110 mg/kg/day, and fluconazole at 0 to 50 mg/kg/day. Meningitis was established in male BALB/c mice by intracerebral injection of C. neoformans. Treatment with flucytosine with or without fluconazole dissolved in the sole source of drinking water was started on day 2; animals were sacrificed at 16 days, and the numbers of fungal colonies in the brain were quantified. A survival rate of 100% was achieved with ABCD plus flucytosine without fluconazole; however, the addition of fluconazole was required to prevent weight loss (P < 0.00001) and to achieve the maximum antifungal effect (P < 0.00001). The only region of dose combinations for which the 99% confidence intervals were less than 100 CFU/g of brain was defined by ABCD at 5.0 to 7.5 mg/kg combined with flucytosine at 20 to 60 mg/kg/day and fluconazole at 30 to 40 mg/kg/day. The triple combination of ABCD plus flucytosine and fluconazole was necessary to achieve the greatest antifungal activity.

Treatment of histoplasmosis with fluconazole in patients with acquired immunodeficiency syndrome. National Institute of Allergy and Infectious Diseases Acquired Immunodeficiency Syndrome Clinical Trials Group and Mycoses Study Group

PURPOSE

This study assesses the efficacy and safety of fluconazole therapy in patients with acquired immunodeficiency syndrome (AIDS) and mild to moderately severe manifestations of disseminated histoplasmosis.

PATIENTS AND METHODS

This was a multicenter, open-label, nonrandomized prospective trial. All patients had AIDS and disseminated histoplasmosis. Patients were treated with 1,200 mg of fluconazole given by mouth once on the first day, then 600 mg once daily for 8 weeks, and those patients who improved clinically were then assigned fluconazole maintenance therapy 200 mg once daily for at least 1 year. Interim analysis revealed a high failure rate (10 of 20, 50%), causing revision of the protocol to increase the fluconazole dose to 1,600 mg given once on the first day, then 800 mg once daily, and the duration to 12 weeks for induction therapy and then 400 mg daily for 1 year for maintenance therapy.

MEASUREMENTS AND MAIN RESULTS

Thirty-six of 49 patients (74%; 95% confidence interval [CI]: 59% to 85%) with mild to moderately severe clinical manifestations who entered into the revised study responded to 800 mg of fluconazole daily for 12 weeks as induction therapy. Of the seven patients who failed induction therapy because of progression of histoplasmosis, one died of the infection. Of 36 patients who entered into the maintenance phase of the study receiving 400 mg of fluconazole daily for 1 year, 11 (30.5%) relapsed, including one who died (2.8%). Two of the 49 patients (4.1%) were removed because of grade 4 adverse events, alkaline phosphatase elevation for one and aspartate aminotransferase elevation in the other. The relapse-free rate at 1 year was 53% (95% CI: 32% to 89%), prompting closure of the study.

CONCLUSIONS

Fluconazole 800 mg daily is a safe and moderately effective induction therapy for mild or moderately severe disseminated histoplasmosis in patients with AIDS. On the basis of historic comparison, fluconazole 400 mg daily is less effective than itraconazole 200 to 400 mg daily or amphotericin B 50 mg given weekly as maintenance therapy to prevent relapse.

Effect of severity of meningitis on fungicidal activity of flucytosine combined with fluconazole in a murine model of cryptococcal meningitis

We studied the effect of the severity of meningitis on the response to therapy with fluconazole and flucytosine in a murine model of cryptococcal meningitis. Meningitis was established by intracerebral injection of Cryptococcus neoformans. The severity of meningitis was varied by delaying the onset of treatment from 3 to 7 days. Animals were sacrificed after 14 days of treatment, and the numbers of C. neoformans per gram of brain tissue were quantified. The range of effective dose combinations of fluconazole and flucytosine became progressively reduced as the severity of meningitis increased. The magnitude of treatment effect, as measured by the numbers of CFU/gram of brain tissue, was also reduced with increasing severity of meningitis. In this model, as the severity of meningitis increases, higher doses of fluconazole are required to achieve equivalent levels of activity. The combination of fluconazole and flucytosine appears to have the most-potent antifungal effects. This is most readily observed in animals with more-severe meningitis.

Regions of Escherichia coli TonB and FepA proteins essential for in vivo physical interactions

The transport of Fe(III)-siderophore complexes and vitamin B12 across the outer membrane of Escherichia coli is an active transport process requiring a cognate outer membrane receptor, cytoplasmic membrane-derived proton motive force, and an energy-transducing protein anchored in the cytoplasmic membrane, TonB. This process requires direct physical contact between the outer membrane receptor and TonB. Previous studies have identified an amino-terminally located region (termed the TonB box) conserved in all known TonB-dependent outer membrane receptors as being essential for productive energy transduction. In the present study, a mutation in the TonB box of the ferric enterochelin receptor FepA resulted in the loss of detectable in vivo chemical cross-linking between FepA and TonB. Protease susceptibility studies indicated this effect was due to an alteration of conformation rather than the direct disruption of a specific site of physical contact. This suggested that TonB residue 160, implicated in previous studies as a site of allele-specific suppression of TonB box mutants, also made a conformational rather than a direct contribution to the physical interaction between TonB and the outer membrane receptors. This possibility was supported by the finding that TonB carboxyl-terminal truncations that retained Gln-160 were unable to participate in TonB-FepA complex formation, indicating that this site alone was not sufficient to support the physical interactions involved in energy transduction. These studies indicated that the final 48 residues of TonB were essential to this physical interaction. This region contains a putative amphipathic helix which could facilitate TonB-outer membrane interaction. Amino acid replacements at one site in this region were found to affect energy transduction but did not appear to greatly alter TonB conformation or the formation of a TonB-FepA complex. The effects of amino acid substitutions at several other TonB sites were also examined.

Structure/activity studies of anti-inflammatory peptides based on a conserved peptide region of the lectin domain of E-, L- and P-selectin

Previously, it was established that the peptide YYWIGIRK-NH2 inhibits both myeloid cell adhesion to selectins in vitro and neutrophil influx into inflammatory sites in vivo (Briggs et al., 1995). Initial structure/activity studies revealed that at least one Y residue at the N-terminus of the peptide was essential for these bioactivities but that the C-terminal K residue was unnecessary for inhibitory activity. We have now synthesized a new series of peptides which contain single residue substitutions at each position of the reference peptide, YYWIGIR-NH2, and have tested these peptides for inhibitory activity in a selectin cell binding assay. In addition, peptides containing single D-amino acids at selected positions, or an all D-configured reference peptide sequence, or the retro-inverso version (rigiwyy-NH2) of the reference peptide sequence have also been analyzed for inhibitory activity in the same assays. Finally, the ability of the reference peptide and a specifically designed control sequence (YY(AIB)IGIR-NH2) to discriminate between potential synthetic saccharide ligands, including sialyl-Lewis x, Lewis x, and sialyl-N-acetyl-lactosamine, was investigated using isothermal titration calorimetry. The results of these studies demonstrate that whereas many single amino acid substitutions are tolerated in the peptide without complete loss of inhibitory activity, substitution at some positions (e.g., the W residue) results in relatively inactive compounds, clearly pointing to the importance of these residues in making critical contacts with the appropriate saccharide ligand. Titration calorimetry revealed that the reference peptide does not discriminate between Lewis x or sialyl-Lewis x in vitro, but binds these saccharides with nearly 40-fold higher affinity (KD 25 microM) than the nonfucosylated trisaccharide, sialyl-N-acetyl-lactosamine. We can infer from these studies that the presence of a sialyl group per se, is not a requisite for complex formation between the reference peptide and its saccharide ligand. Substitution of single D-amino acid residues at various positions in the reference peptide sequence reduces or eliminates all inhibitory properties. However, the all D-configured peptide or the retro-inverso peptide sequence have greater activity than the all L-configured reference peptide in the in vitro biological assays, and each was an effective inhibitor of neutrophil infiltration in a thioglycolate-induced mouse peritonitis model. These results, combined with the results of titration, allow us to conclude that binding between the reference peptide and its saccharide ligand, which affords its inhibitory properties, is mediated by the presence of a contiguous, nonpolar surface, or face, presented at the N-terminus of the reference peptide, likely encompassing the sequence YYWI. Furthermore, the W plays a critical role in binding, probably through formation of an essential hydrogen bond with a suitably juxtaposed group carried on the saccharide ligand.

Effect of fluconazole on fungicidal activity of flucytosine in murine cryptococcal meningitis

Both animal and in vitro studies have demonstrated that combinations of flucytosine with amphotericin B and with fluconazole have significantly improved activity against cryptococcal meningitis compared with the activity of each drug used alone. However, very few dose levels of these agents have been tested in combination. This study evaluated the efficacy of fluconazole plus flucytosine in a murine model of cryptococcal meningitis over a broad range of dose combinations (fluconazole, 0 to 40 micrograms/g of body weight per day; flucytosine, 0 to 200 micrograms/g/day). Both drugs were dissolved in drinking water, with treatment on days 2 to 11. In this highly reproducible model, fluconazole had a dramatic effect on the fungicidal activity of flucytosine. Flucytosine at dose levels of as much as 200 micrograms/g/day alone or in combination with low doses of fluconazole had minimal fungicidal activity, whereas in combination with fluconazole at 24 to 40 micrograms/g/day, flucytosine showed fungicidal activity in the range of 45 to 65% of the animals treated at doses of 40 to 100 micrograms/g/day. This striking effect of fluconazole is consistent with the results of both in vitro and clinical studies. In the clinic, the use of flucytosine is often limited by severe toxicity, while toxicity is rarely observed with fluconazole. These results suggest that when flucytosine is given with higher doses of fluconazole, the maximum therapeutic effect of the former in the clinic may be observed at dose levels that are far less than the doses commonly employed (150 micrograms/g daily).

Identification of TonB homologs in the family Enterobacteriaceae and evidence for conservation of TonB-dependent energy transduction complexes

The transport of Fe(III)-siderophore complexes and vitamin B12 across the outer membrane of Escherichia coli requires the TonB-dependent energy transduction system. A set of murine monoclonal antibodies (MAbs) was generated against an E. coli TrpC-TonB fusion protein to facilitate structure and function studies. In the present study, the epitopes recognized by these MAbs were mapped, and their distribution in gram-negative organisms was examined. Cross-species reactivity patterns obtained against TonB homologs of known sequence were used to refine epitope mapping, with some epitopes ultimately confirmed by inhibition experiments using synthetic polypeptides. Epitopes recognized by this set of MAbs were conserved in TonB homologs for 9 of 12 species in the family Enterobacteriaceae (including E. coli), including previously unidentified TonB homologs in Shigella, Citrobacter, Proteus, and Kluyvera species. These homologs were also detected by a polyclonal alpha-TrpC-TonB serum that additionally recognized the known Yersinia enterocolitica TonB homolog and a putative TonB homolog in Edwardsiella tarda. These antibody preparations failed to detect the known TonB homologs of either Pseudomonas putida or Haemophilus influenzae but did identify potential TonB homologs in several other nonenteric gram-negative species. In vivo chemical cross-linking experiments demonstrated that in addition to TonB, auxiliary components of the TonB-dependent energy transduction system are broadly conserved in members of the family Enterobacteriaceae, suggesting that the TonB system represents a common system for high-affinity active transport across the gram-negative outer membrane.

Identification of patients with acute AIDS-associated cryptococcal meningitis who can be effectively treated with fluconazole: the role of antifungal susceptibility testing

No method currently exists to predict which patients with acute AIDS-associated cryptococcal meningitis can be effectively treated with fluconazole. The objective of this study was to determine the relationship of cryptococcal susceptibility to fluconazole, along with clinical variables, to the risk of treatment failure for patients with acute AIDS-associated cryptococcal meningitis. Results of in vitro fluconazole susceptibility testing of cryptococcal isolates and data from two clinical trials were analyzed. Susceptibility to fluconazole was determined by means of both microtiter and macrobroth (M27-P) dilution methods. Treatment was defined as successful if the patient was alive at 10 weeks and if a cerebrospinal fluid culture was sterile at that time. Seventy-six patients receiving fluconazole +/- flucytosine were included; therapy failed for 19. Patients whose therapy failed were more likely to have a positive blood and urine culture and a higher titer in serum and cerebrospinal fluid of cryptococcal antigen, and the MIC of fluconazole against their isolates (as determined by the microtiter method) was more likely to be higher; they were less likely to have received flucytosine. Logistic regression modeling revealed that a negative blood culture, a low MIC of fluconazole (per the microtiter method), and treatment with flucytosine were factors independently associated with successful treatment.

Characterization of the exbBD operon of Escherichia coli and the role of ExbB and ExbD in TonB function and stability

TonB protein appears to couple the electrochemical potential of the cytoplasmic membrane to active transport across the essentially unenergized outer membrane of gram-negative bacteria. ExbB protein has been identified as an auxiliary protein in this process. In this paper we show that ExbD protein, encoded by an adjacent gene in the exb cluster at 65', was also required for TonB-dependent energy transduction and, like ExbB, was required for the stability of TonB. The phenotypes of exbB exbD+ strains were essentially indistinguishable from the phenotypes of exbB+ exbD strains. Mutations in either gene resulted in the degradation of TonB protein and in decreased, but not entirely absent, sensitivities to colicins B and Ia and to bacteriophage phi 80. Evidence that the absence of ExbB or ExbD differentially affected the half-lives of newly synthesized and steady-state TonB was obtained. In the absence of ExbB or ExbD, newly synthesized TonB was degraded with a half-life of 5 to 10 min, while the half-life of TonB under steady-state conditions was significantly longer, approximately 30 min. These results were consistent with the idea that ExbB and ExbD play roles in the assembly of TonB into an energy-transducing complex. While interaction between TonB and ExbD was suggested by the effect of ExbD on TonB stability, interaction of ExbD with TonB was detected by neither in vivo cross-linking assays nor genetic tests for competition. Assays of a chromosomally encoded exbD::phoA fusion showed that exbB and exbD were transcribed as an operon, such that ExbD-PhoA levels in an exbB::Tn10 strain were reduced to 4% of the levels observed in an exbB+ strain under iron-limiting conditions. Residual ExbD-PhoA expression in an exbB::Tn10 strain was not iron regulated and may have originated from within the Tn10 element in exbB.

Itraconazole treatment of disseminated histoplasmosis in patients with the acquired immunodeficiency syndrome. AIDS Clinical Trial Group

PURPOSE

Amphotericin B has been the treatment of choice for disseminated histoplasmosis in patients with acquired immunodeficiency syndrome (AIDS). Oral antifungal agents would be welcome alternatives to standard treatment of disseminated histoplasmosis in less severe cases. The purpose of this study was to assess the efficacy and safety of itraconazole therapy in patients with AIDS and disseminated histoplasmosis.

PATIENTS AND METHODS

This was a multicenter, open-label, nonrandomized prospective trial conducted in university hospitals of the AIDS Clinical Trial Group. All patients had AIDS and first episodes of disseminated histoplasmosis. Patients with central nervous system involvement or with severe clinical manifestations were excluded. Patients were treated with itraconazole BID by mouth 300 mg for 3 days and then 200 mg BID for 12 weeks. Resolution of clinical findings, clearance of positive cultures, and drug tolerance were the main outcome measurements. A secondary objective was effect of therapy on Histoplasma capsulatum var capsulatum antigen levels.

RESULTS

Of 59 evaluable patients, 50 (85%) responded to therapy. Five patients withdrew because of progressive infection, 1 died of a presumed pulmonary embolus within the first week of therapy without improvement, 2 withdrew because of toxicity, and 1 was lost to follow-up after week 2 of therapy. Patients with moderately severe clinical (fever > 39.5 degrees C or Karnofsky score < 60) or laboratory abnormalities (alkaline phosphatase > 5 times normal or albumin < 3 g/dL) at baseline tended to respond more poorly than did other patients. Resolution of complaints of fever and improvement in fatigue occurred after a median of 3 and 6 weeks, respectively, and weight gain after 2 weeks. Fungemia cleared after a median of 1 week. H capsulatum var capsulatum antigen cleared from the urine and serum at rates of 0.2 and 0.3 units per week, respectively.

CONCLUSIONS

Itraconazole is safe and effective induction therapy for mild disseminated histoplasmosis in patients with AIDS, offering an alternative to amphotericin B in such cases. Patients with moderately severe or severe histoplasmosis should first be treated with amphotericin B and then may be switched to itraconazole after achieving clinical improvement.

Fluconazole combined with flucytosine for treatment of cryptococcal meningitis in patients with AIDS

Treatment of cryptococcal meningitis with amphotericin B or fluconazole is often unsuccessful; in only 35%-40% of cases do CSF cultures become negative by 10 weeks after initiation of such therapy. We conducted a prospective, open-label clinical trial involving persons with AIDS to determine whether the rate of clinical success would improve when fluconazole (400 mg daily) was combined with flucytosine (150 mg/kg daily). At the conclusion of 10 weeks of therapy, 75% (95% confidence interval, 58%-87%) of 32 subjects' CSF cultures were negative. The Kaplan-Meier estimate of clinical success at 10 weeks was 63% (95% confidence interval, 48%-82%). The median time to negativity of the CSF culture was 23 days. Toxic side effects that were sufficiently severe to lead to the withdrawal of flucytosine were observed in nine subjects (28%). In this pilot study of fluconazole combined with flucytosine, the rate of clinical success at 10 weeks was greater than that previously reported with regard to the use of fluconazole alone or amphotericin B alone.

Partial suppression of an Escherichia coli TonB transmembrane domain mutation (delta V17) by a missense mutation in ExbB

Active transport of vitamin B12 and Fe(III)-siderophore complexes across the outer membrane of Escherichia coli appears to be dependent upon the ability of the TonB protein to couple cytoplasmic membrane-generated protonmotive force to outer membrane receptors. TonB is supported in this role by an auxiliary protein, ExbB, which, in addition to stabilizing TonB against the activities of endogenous envelope proteases, directly contributes to the energy transduction process. The topological partitioning of TonB and ExbB to either side of the cytoplasmic membrane restricts the sites of interaction between these proteins primarily to their transmembrane domains. In this study, deletion of valine 17 within the aminoterminal transmembrane anchor of TonB resulted in complete loss of TonB activity, as well as loss of detectable in vivo crosslinking into a 59 kDa complex believed to contain ExbB. The delta V17 mutation had no effect on TonB export. The loss of crosslinking appeared to reflect conformational changes in the TonB/ExbB pair rather than loss of interaction since ExbB was still required for some stabilization of TonB delta V17. Molecular modeling suggested that the delta V17 mutation caused a significant change in the predicted conserved face of the TonB amino-terminal membrane anchor. TonB delta V17 was unable to achieve the 23 kDa proteinase K-resistant form in lysed sphaeroplasts that is characteristic of active TonB. Wild-type TonB also failed to achieve the proteinase K-resistant configuration when ExbB was absent. Taken together these results suggested that the delta V17 mutation interrupted productive TonB-ExbB interactions. The apparent ability to crosslink to ExbB as well as a limited ability to transduce energy were restored by a second mutation (A39E) in or near the first predicted transmembrane domain of the ExbB protein. Consistent with the weak suppression, a 23 kDa proteinase K-resistant form of TonB delta V17 was not observed in the presence of ExbBA39E. Neither the ExbBA39E allele nor the absence of ExbB affected TonB or TonB delta V17 export. Unlike the tonB delta V17 mutation, the exbBA39E mutation did not greatly alter a modelled ExbB transmembrane domain structure. Furthermore, the suppressor ExbBA39E functioned normally with wild-type TonB, suggesting that the suppressor was not allele specific. Contrary to expectations, the TonB delta V17, ExbBA39E pair resulted in a TonB with a greatly reduced half-life (approximately 10 min). These results together with protease susceptibility studies suggest that ExbB functions by modulating the conformation of TonB.

Evaluation of neurosyphilis in human immunodeficiency virus-infected individuals

The diagnosis of neurosyphilis in patients infected with the human immunodeficiency virus (HIV) remains problematic. We examined the use of the Treponema pallidum hemagglutination (TPHA) index and quantitative tests of CSF by means of microhemagglutination-T. pallidum for diagnosis of neurosyphilis in 58 HIV-infected persons with latent syphilis who had not recently received therapy for syphilis. Five patients (9%) had reactive CSF VDRL tests and thus had proven neurosyphilis. For 13 patients (22%), CSF findings were normal and revealed no evidence of neurosyphilis. For 40 patients (69%), abnormal CSF findings were characteristic of neurosyphilis, but their CSF VDRL tests were nonreactive. Twenty-five of the 40 patients with possible neurosyphilis had pleocytosis and elevated CSF levels of protein and/or IgG. Five (12.5%) of these 40 patients had positive TPHA indices that indicated intrathecal antitreponemal antibody production, a finding that provided greater support for the diagnosis of active neurosyphilis. With use of the TPHA index, patients with CSF abnormalities can be better classified in regard to their need for therapy for neurosyphilis.

Treatment of coccidioidomycosis with SCH 39304

A new oral triazole antifungal, SCH 39304, was administered to 54 patients with progressive infections due to Coccidioides immitis from six collaborating centers. Patients were grouped according to site of infection including chronic pulmonary (25), bone/joint (17) and skin/soft tissue (12). The median age was 40 years; 83% were male, 52% white, 13% HIV-infected and 35% had failed previous therapy. The majority of patients were treated with either 100 mg or 200 mg day-1. One patient on renal dialysis received 300 mg day-1. Baseline abnormalities were reassessed for evidence of efficacy every 4 months and expressed in a standardized scoring system. Cumulative overall response rates at 4, 8 and 12 months were 7%, 36% and 66% respectively. Twelve month response rates by disease were 77% (pulmonary), 62% (skin/soft tissue) and 31% (bone/joint). Fifteen patients failed therapy although seven of these were still on treatment when the study was discontinued. Two failed due to toxicity. Possible symptoms or signs of toxicity occurred in 24 (44%) patients and were generally mild. SCH 39304 is an effective and well tolerated therapy for progressive forms of coccidioidomycosis.

The conserved proline-rich motif is not essential for energy transduction by Escherichia coli TonB protein

TonB protein functions as an energy transducer, coupling cytoplasmic membrane electrochemical potential to the active transport of vitamin B12 and Fe(III)-siderophore complexes across the outer membrane of Escherichia coli and other Gram-negative bacteria. Accumulated evidence indicates that TonB is anchored in the cytoplasm, but spans the periplasmic space to interact physically with outer membrane receptors. It has been presumed that this ability is caused by a conserved (Glu-Pro)n-(Lys-Pro)m repeat motif, predicted to assume a rigid, linear conformation of sufficient length to reach the outer membrane. Based on in vitro studies with synthetic peptides and purified FhuA outer membrane receptor, it has been suggested that this region contains a site that directly binds outer membrane receptors and is essential for energy transduction. We have found a TonB lacking the (Glu-Pro)n-(Lys-Pro)m repeat motif (TonB delta(66-100)). TonB delta(66-100) is fully capable of irreversible phi 80 adsorption, except under physiological circumstances where the periplasmic space is expanded. Based on the ability of TonB delta(66-100) to interact with outer membrane receptors and components of the energy transduction apparatus under normal physiological conditions, it is evident that the TonB proline-rich region has no role in energy transduction other than to provide a physical extension sufficient to reach the outer membrane.

Fluconazole therapy for coccidioidal meningitis. The NIAID-Mycoses Study Group

OBJECTIVE

To determine the efficacy and safety of fluconazole treatment of coccidioidal meningitis.

DESIGN

Uncontrolled clinical trial.

SETTING

Four university-based treatment centers in California, Arizona, and Texas. Most therapy was conducted without hospitalization.

PATIENTS

Fifty consecutive patients with active coccidioidal meningitis, of which 47 (94%) were evaluable. Twenty-five patients had received no previous treatment for their meningitis, and nine had coinfection with human immunodeficiency virus (HIV).

INTERVENTION

Fluconazole was administered in an oral dose of 400 mg once per day for up to 4 years (median, 37 months) in responding patients. Concurrent therapy with another antifungal agent was prohibited.

MEASUREMENTS

Predefined assessment of infection-related abnormalities was done at the time of enrollment and was repeated at least every 4 months during treatment. Elimination of 40% or more of baseline abnormalities was considered a response.

RESULTS

Thirty-seven of 47 (79%; 95% CI, 61% to 90%) evaluable patients responded to treatment. Response rates were similar for patients with and without previous therapy, for patients with and without concomitant HIV infection, and for patients with and without pre-existing hydrocephalus. Most improvement occurred within 4 to 8 months after starting treatment. Patient symptoms resolved more quickly than did cerebrospinal fluid abnormalities. In 15 of 20 responding patients followed for 20 months or more, residual low-level cerebrospinal fluid abnormalities remained throughout therapy. No patient discontinued therapy because of drug-related side effects, although confusion developed in two patients that resolved when the dose of fluconazole was reduced.

CONCLUSION

Fluconazole therapy is often effective in suppressing coccidioidal meningitis.

Catastrophic visual loss due to Cryptococcus neoformans meningitis

We have reviewed our experience with 17 of our own patients with cryptococcal meningitis and 32 cases from the literature. Although this complication is an uncommon event, patients with cryptococcal meningitis may develop visual loss in the absence of other ocular lesions (endophthalmitis or cryptococcomas in the visual pathway) that could explain the visual symptoms. There are 2 distinct patterns of visual loss: rapid visual loss and slow visual loss. Rapid visual loss is characterized by onset of profound visual loss over a period as short as 12 hours before or early in the course of therapy and a clinical syndrome that is strongly suggestive of optic neuritis. Direct invasion of the optic nerve by C. neoformans is demonstrated by cases in this and other reports. Slow visual loss is characterized by slow but progressive visual loss which typically begins later during therapy and may be due to the effects of increased intracranial pressure. While the initial deficit may be mild, patients with slow visual loss can progress to severe visual loss over weeks to months. The only factors that appear to predict either pattern of visual loss are the presence of papilledema, an elevated CSF opening pressure, and a positive CSF India ink preparation. In the 25 visual loss patients for whom data were available for all 3 items, 10 (40%) were positive for all 3, as opposed to only 4 of 114 (3.5%) from a reference group of cryptococcal meningitis patients without visual loss (p < 0.00001). The only therapeutic measures with any degree of consistent success were those directed at reducing intracranial pressure. When begun early and used aggressively, such therapy halted and sometimes even reversed the course of visual loss, particularly in the slow visual loss group. Corticosteroids did not appear to be of value in the small number of patients who received them.

Tuberculous meningitis in patients with and without human immunodeficiency virus infection

OBJECTIVE

To characterize the symptoms, signs, laboratory findings, and outcome of culture-proven meningitis due to Mycobacterium tuberculosis in patients with and without human immunodeficiency virus (HIV) infection.

DESIGN

Retrospective chart review.

SETTING

Urban public general hospital in the United States.

PATIENTS

Fifteen patients with and 16 without HIV infection.

MEASUREMENTS

Demographics, symptoms, physical exam findings, serum sodium, complete blood cell count, CD4+ cell count, cerebrospinal fluid findings, imaging data, and in-hospital mortality.

MAIN RESULTS

Symptoms, signs, chest radiograph appearance, cerebrospinal fluid cell counts and chemistries, and mortality were similar in both groups (p = NS). Median CD4+ cell counts were lower in HIV-infected patients (median 99/mm3, range 7 to 251, versus 384/mm3, range 171 to 724 in those without HIV infection, p = 0.007). Intracerebral mass lesions were more common in the HIV-infected group (60% versus 14% in the uninfected group, p = 0.01), although the presence of a mass did not correlate with focal neurologic deficits, altered level of consciousness, or mortality.

CONCLUSION

With the exception of an increased incidence of intracerebral mass lesions in HIV-infected individuals, HIV infection appears to have little impact on the findings and in-hospital mortality of tuberculous meningitis.

Prevalence of neurosyphilis in human immunodeficiency virus-infected patients with latent syphilis

PURPOSE

A prospective study was done to determine the prevalence of confirmed neurosyphilis (cerebrospinal fluid [CSF] Venereal Disease Research Laboratory [VDRL]-reactive) in human immunodeficiency virus (HIV)-infected patients with latent syphilis (reactive serum rapid plasma reagin [RPR] and microhemagglutination-Treponema pallidum [MHA-TP]).

PATIENTS AND METHODS

All HIV-infected patients seen for their first visit at the Los Angeles County/University of Southern California Medical Center AIDS Clinic from June through December 1990 were screened for latent syphilis. Those with reactive serum RPRs and MHA-TPs who had not received recent (within 6 months) therapy for syphilis were offered diagnostic CSF sampling.

RESULTS

A total of 312 patients were screened, of whom 71 (22.8%) had reactive serum RPRs and MHA-TPs. Thirty-three of these patients (47%) had diagnostic CSF sampling (26 refused lumbar puncture or were lost to follow-up; 12 had had recent therapy for syphilis and thus did not have CSF sampling). Among the 33 patients who had CSF sampling, 20 (60.6%) had normal CSF profiles (white blood cell count less than 8/mm3; protein less than 0.60 g/L; glucose greater than 2.8 mmol/L) and nonreactive CSF VDRLs. Ten of the 33 patients (30.3%) had abnormal CSF profiles and nonreactive CSF VDRLs, and three of 33 (9.1%) had reactive CSF VDRLs.

CONCLUSIONS

Asymptomatic neurosyphilis was found in 9.1% of our patient population undergoing CSF sampling, giving a 1.0% prevalence of CSF VDRL-reactive neurosyphilis in the population we screened. The abnormal CSF findings may have been due to either nonreactive CSF VDRL neurosyphilis, central nervous system infection with HIV, or infection with some unrecognized agent.

Case report: recurrent Salmonella typhi chest wall abscess associated with a pituitary macroadenoma

An unusual manifestation of a Salmonella typhi infection is presented in a patient with a growth hormone producing tumor. Growth hormone may effect cell mediated immunity and predispose to localized or disseminated intracellular infections.

Control of alkaline phosphatase activity in C3H10T1/2 cells: role of retinoic acid and cell density

The enzyme alkaline phosphatase (AP) has been shown to be lost or inappropriately expressed during carcinogenesis in some tissues. Because retinoic acid (RA) appears to play a role in the normal regulation of the enzyme (RA up-regulates AP in a variety of cell types) we have suggested that altered AP expression in some cancers may be caused by a defect in the ability of the cells to respond normally to retinoid. We have begun to use the chemically transformable mouse embryo fibroblast cell, C3H10T1/2, to investigate this possibility. In this initial study we characterized AP regulation in normal C3H10T1/2 cells and show that: (1) 10(-7) M RA increases AP activity within 3-4 h in serum-free medium; (2) serum inhibits short-term induction (0-8 h) in a concentration-dependent manner (10% serum causes complete inhibition); (3) during long-term RA exposure (24 h and 48 h), induction can be detected in serum-containing medium; (4) AP induction is dose related at RA concentrations from 10(-10) M to 10(-6) M in serum-free medium; (5) 10(-5) M RA is ineffective at inducing AP in serum-free medium during 8 h but is the most effective concentration in serum-containing medium during 24 h and 48 h exposures; (6) AP inducibility by RA requires near-confluent cell densities; and (7) when cultures become confluent, cells become constitutive for AP and no longer require RA for enzyme expression. The effects of serum and cell density on AP inducibility by RA and implications of the RA up-regulation of AP for teratogenesis are discussed.

Abdominal angiostrongyliasis mimicking acute appendicitis and Meckel's diverticulum: report of a case in the United States and review

Two cases of children with abdominal angiostrongyliasis acquired within the United States are reported. The index patient presented with complaints consistent with appendicitis, but at surgery findings were thought to represent an atypical presentation of a Meckel's diverticulum. His sole sibling (sister) had eosinophilia, no other intestinal parasites on fecal examination, and a positive serologic test, all suggesting infection with Angiostrongylus costaricensis. Because infections with this parasite are not known to result from human-to-human transmission, his sister's infection represents a second case.

Randomized trial of meatal care with silver sulfadiazine cream for the prevention of catheter-associated bacteriuria

A randomized, controlled, prospective clinical trial involving 696 hospitalized patients was undertaken to determine the effectiveness of 1% silver sulfadiazine cream applied twice daily to the urethral meatus in preventing transurethral catheter-associated bacteriuria. The overall incidence of bacteriuria was 11.4% (38/332) in the treated group and 13.2% (48/364) in the untreated group (P = .56; odds ratio, 0.85; 95% confidence interval, 0.53-1.37). Cox proportional hazards analysis identified female sex, lack of antibiotic use, and a positive initial meatal culture (but not treatment randomization or lack of urinemeter use) as independent variables associated with an increased risk of bacteriuria. Survival curve analysis of subgroups stratified by sex and antibiotic use failed to detect an effect of silver sulfadiazine on the rate of bacteriuria. Meatal care with silver sulfadiazine cream did not prevent the development of catheter-associated bacteriuria in short-term catheterized patients.