Gregory M. Anstead

The estradiol pharmacophore : Ligand structure-estrogen receptor binding affinity relationships and a model for the receptor binding site

The accumulated knowledge on the binding of estradiol (E2) and its analogs and the results of affinity-labeling studies have been reviewed and are used herein to derive a binding site model for the estrogen receptor (ER). Estradiol is nonpolar and hydrophobic, except at its molecular termini. Most of its skeletal flexibility resides in the B-ring, and it probably binds in a low-energy conformation. The phenolic OH group in the A-ring contributes about 1.9 kcal/mol to the binding free energy and probably acts primarily as a hydrogen bond donor. The 17 beta-hydroxyl group in the D-ring contributes approximately 0.6 kcal/mol to the binding and probably acts as a hydrogen bond acceptor, either directly or via a water molecule. There also seems to be a degree of flexibility in the region of the receptor that encompasses the D-ring. The aromatic ring contributes about 1.5 kcal/mol, probably through weak polar interactions with receptor residues that contact the beta-face of the steroid. The receptor seems to surround the ligand, so that all four rings contribute significantly to binding. Small hydrophobic substituents enhance binding affinity at positions 4, 12 beta, 14, and 16 alpha; whereas, larger hydrophobic substituents are tolerated at positions 7 alpha, 11 beta, and 17 alpha. In general, the ER is intolerant of polar substituents. Based on E2 analogs bearing affinity-labeling groups, cysteine residues might be present in the binding site in the area of C-4, C-17 alpha, and C-17 beta, and a lysine residue might be located near C-16. Models that represent the limits of deformability of the ligand binding site, the position of preformed pockets, and space occupied by the receptor are presented. The various elements in this model for the binding of steroidal estrogens by the estrogen receptor are consistent with evidence emerging from the crystal structures of related nuclear hormone receptor ligand complexes.

Malnutrition Alters the Innate Immune Response and Increases Early Visceralization following Leishmania donovani Infection

ABSTRACT Malnutrition is a risk factor for the development of visceral leishmaniasis. However, the immunological basis for this susceptibility is unknown. We have developed a mouse model to study the effect of malnutrition on innate immunity and early visceralization following Leishmania donovani infection. Three deficient diets were studied, including 6, 3, or 1% protein; these diets were also deficient in iron, zinc, and calories. The control diet contained 17% protein, was zinc and iron sufficient, and was provided ab libitum. Three days after infection with L. donovani promastigotes, the total extradermal (lymph nodes, liver, and spleen) and skin parasite burdens were equivalent in the malnourished (3% protein) and control mice, but in the malnourished group, a greater percentage (39.8 and 4.0%, respectively;P = 0.009) of the extradermal parasite burden was contained in the spleen and liver. The comparable levels of parasites in the footpads in the two diet groups and the higher lymph node parasite burdens in the well-nourished mice indicated that the higher visceral parasite burdens in the malnourished mice were not due to a deficit in local parasite killing but to a failure of lymph node barrier function. Lymph node cells from the malnourished, infected mice produced increased levels of prostaglandin E2(PGE2) and decreased levels of interleukin-10. Inducible nitric oxide synthase activity was significantly lower in the spleen and liver of the malnourished mice. Thus, malnutrition causes a failure of lymph node barrier function after L. donovani infection, which may be related to excessive production of PGE2and decreased levels of IL-10 and nitric oxide.

Posaconazole for the Treatment of Azole-Refractory Oropharyngeal and Esophageal Candidiasis in Subjects with HIV Infection

BACKGROUND We evaluated the efficacy and safety of oral posaconazole for human immunodeficiency virus (HIV)-infected subjects with oropharyngeal candidiasis (OPC) and/or esophageal candidiasis (EC) who were clinically refractory to treatment with oral fluconazole or itraconazole. METHODS Subjects with confirmed OPC or EC who did not improve after receiving standard courses of fluconazole or itraconazole treatment were eligible for study enrollment. Subjects received either oral posaconazole (400 mg twice daily) for 3 days followed by oral posaconazole (400 mg once daily) for 25 days (regimen A; 103 patients) or oral posaconazole (400 mg twice daily) for 28 days (regimen B; 96 patients). The primary end point was cure or improvement after 28 days. Primary efficacy analyses were performed on the subset of treated subjects with refractory disease (e.g., baseline culture positive for fluconazole- or itraconazole-resistant Candida species or persistent or progressive clinical signs or symptoms consistent with treatment failure). RESULTS Of the modified intent-to-treat population, 132 (75%) of 176 subjects achieved a clinical response to posaconazole treatment. Clinical response rates were similar between regimen A recipients (75.3%) and regimen B recipients (74.7%). Clinical responses occurred in 67 (73%) of 92 subjects with baseline isolates resistant to fluconazole, 49 (74%) of 66 subjects with baseline isolates resistant to itraconazole, and 42 (74%) of 57 subjects with isolates resistant to both. Clinical response was achieved in 32 (74.4%) of 43 subjects with endoscopically documented EC. The most common treatment-related adverse events were diarrhea (11%), neutropenia (7%), flatulence (6%), and nausea (6%). Eight subjects (4%) discontinued therapy as a result of a treatment-related adverse event. CONCLUSIONS Posaconazole offers a safe and effective treatment option for HIV-infected subjects with azole-refractory OPC and/or EC.

Refractory coccidioidomycosis treated with posaconazole

BACKGROUND Disseminated coccidioidomycosis (which is caused by the endemic fungi of the genus Coccidioides) can be a life-threatening systemic fungal infection. Although conventional antifungal therapies have activity against Coccidioides, the disease can be refractory to standard therapies. Drug-associated toxicities also may limit the clinical utility of the standard antifungal drugs. In addition, relapses in patients with disseminated coccidioidomycosis are common, making long-term management of this disease challenging. METHODS We report the outcomes of 6 patients with coccidioidomycosis who were treated with posaconazole salvage therapy after treatment with conventional antifungal therapies failed to produce sustained clinical improvement. Patients were administered posaconazole oral suspension 800 mg/day in divided doses as part of an open-label clinical trial. A modified version of the Mycoses Study Group Coccidioides scoring system was used to evaluate the burden of disease. Posaconazole therapy resulted in rapid clinical improvements in the signs and symptoms of coccidioidomycosis. RESULTS At the end of therapy, 5 of 6 patients had successful outcomes. Posaconazole was well tolerated despite long-term administration (1-2 years), and 2 patients continued to receive posaconazole maintenance therapy at the time of writing. CONCLUSIONS The successful outcomes observed in this case series suggest that posaconazole is an effective therapy for coccidioidomycosis.

Recent advances in the treatment of infections due to resistant Staphylococcus aureus.

Purpose of review This paper reviews recent data on the treatment of infections caused by drug-resistant Staphylococcus aureus, particularly methicillin-resistant S. aureus (MRSA). This review will focus on new findings reported in the English-language medical literature from June 2003 to September 2004. Recent findings Despite the emergence of resistant and multidrug-resistant S. aureus, we have three effective drugs in clinical use for which little resistance has been observed: quinupristin-dalfopristin, linezolid, and daptomycin. Linezolid looks particularly promising in the treatment of MRSA pneumonia. Daptomycin displays rapid bactericidal activity in vitro, but, so far, clinical trials have only been conducted for the treatment of skin and soft-tissue infections. There are three drugs with broad-spectrum activity against Gram-positive organisms at an advanced stage of testing: two new glycopeptides with potent bacteriocidal activity and long half-lives (oritavancin and dalbavancin), and tigecycline, a minocycline derivative. These drugs have also shown efficacy in the treatment of skin and soft-tissue infections. Summary The promising data that have emerged in the last year indicate that we may have six available drugs to treat resistant S. aureus infections within the next few years. The next goal is to determine the appropriate indications and cost-effectiveness of each of these drugs in our treatment strategy against S. aureus and other Gram-positive pathogens.

Phenytoin in Wound Healing

OBJECTIVE: To describe a patient with a massive Grade IV pressure ulcer that responded rapidly to treatment with topical phenytoin and to review the literature supporting the use of this therapy. CASE SUMMARY: A 55-year-old morbidly obese white man (266 kg), with respiratory failure secondary to obesity-hypoventilation syndrome and heart failure, developed pressure ulcers on his lower back and sacrum within the first 2 weeks of hospitalization. Traditional methods of treatment were unsuccessful, and by day 79, the wound involved the entire lumbosacral area and buttocks, and had extensive undermining and sinus tract formation. Within 2 days of applying topical phenytoin, fresh granulation tissue was apparent. After 54 days of treatment, nearly all the sinus tracts were healed. Four months after treatment with topical phenytoin was begun, the sacral wound was nearly healed and the lumbar wound was much reduced in size. It was evident that phenytoin had facilitated the healing of the wounds, even though the patients multiple underlying medical problems had not resolved. DISCUSSION: Phenytoin has been used in the healing of pressure sores, venous stasis and diabetic ulcers, traumatic wounds, and bums. Many of the existing clinical studies have methodologic flaws, such as inappropriate statistical analysis, inadequate control groups, and the absence of randomization and double-blinding. Nevertheless, all the studies have reported enhancement of wound healing, with insignificant adverse effects. Phenytoin may promote wound healing by a number of mechanisms, including stimulation of fibroblast proliferation, facilitation of collagen deposition, glucocorticoid antagonism, and antibacterial activity. CONCLUSIONS: Phenytoin promoted the healing of a massive, necrotizing soft tissue wound that was unresponsive to conventional treatment. Clinical success in this difficult case and the other reports in the literature suggest that phenytoin is effective in wound healing and deserves further investigation.

Multinutrient undernutrition dysregulates the resident macrophage proinflammatory cytokine network, nuclear factor-κB activation, and nitric oxide production

We have described previously a murine model of multinutrient undernutrition that reproduced the features of moderate human malnutrition and led to increased early dissemination of Leishmania donovani. Peritoneal cells from these malnourished mice produced decreased NO after stimulation with IFN‐γ/LPS. We hypothesized that malnutrition may cause a deficit in NF‐κB activation, a principal transcription pathway for inducible NO synthase and proinflammatory cytokines. Macrophages from malnourished mice, stimulated with IFN‐γ/LPS, showed increased IL‐6 production and decreased IL‐10 and TNF‐α production. Neutralization of TNF‐α in macrophage cultures from the control mice mimicked the effect of malnutrition on NO and IL‐10 production, whereas supplemental TNF‐α added to cultures of macrophages from malnourished mice increased NO secretion. NF‐κB nuclear binding activity in macrophages from the malnourished mice was reduced early after stimulation, but increased to supranormal values by 16‐ or 24‐h poststimulation. Blocking NO production in the macrophages from the control mice reproduced the effect of malnutrition on the late activation of NF‐κB, whereas supplemental NO decreased the late NF‐κB activation in the malnourished mice. Thus, in macrophages from the malnourished mice, initial deficits in NF‐κB activity probably lead to decreased TNF‐α, which results in decreased NO; however, IL‐6 is regulated independently from NF‐κB and TNF‐α. The late activation of NF‐κB in the macrophages from malnourished mice is due to absence of negative feedback from NO.

Adiaspiromycosis Causing Respiratory Failure and a Review of Human Infections Due to Emmonsia and Chrysosporium spp.

ABSTRACT We report a case of a 27-year-old male who presented with respiratory distress that required mechanical ventilation. Transbronchial biopsy revealed adiaspores of the fungus Emmonsia crescens within granulomata, a condition known as adiaspiromycosis. The patient received amphotericin products and corticosteroids, followed by itraconazole, and made a full recovery. Emmonsia crescens is a saprobe with a wide distribution that is primarily a rodent pathogen. The clinical characteristics of the 20 cases of human pulmonary adiaspiromycosis reported since the last comprehensive case review in 1993 are described here, as well as other infections recently reported for the genus Emmonsia. Pulmonary adiaspiromycosis has been reported primarily in persons without underlying host factors and has a mild to severe course. It remains uncertain if the optimal management of severe pulmonary adiaspiromycosis is supportive or if should consist of antifungal treatment, corticosteroids, or a combination of the latter two. The classification of fungi currently in the genus Emmonsia has undergone considerable revision since their original description, including being grouped with the genus Chrysosporium at one time. Molecular genetics has clearly differentiated the genus Emmonsia from the Chrysosporium species. Nevertheless, there has been a persistent confusion in the literature regarding the clinical presentation of infection with fungi of these two genera; to clarify this matter, the reported cases of invasive Chrysosporium infections were reviewed. Invasive Chrysosporium infections typically occur in impaired hosts and can have a fatal course. Based on limited in vitro susceptibility data for Chrysosporium zonatum, amphotericin B is the most active drug, itraconazole susceptibility is strain-dependent, and fluconazole and 5-fluorocytosine are not active.

High Risk of Obesity and Weight Gain for HIV-Infected Uninsured Minorities

Background:Obesity and HIV disproportionately affect minorities and have significant health risks, but few studies have examined disparities in weight change in HIV-seropositive (HIV+) cohorts. Objective:To determine racial and health insurance disparities in significant weight gain in a predominately Hispanic HIV+ cohort. Methods:Our observational cohort study of 1214 nonunderweight HIV+ adults from 2007 to 2010 had significant weight gain [≥3% annual body mass index (BMI) increase] as the primary outcome. The secondary outcome was continuous BMI over time. A 4-level race–ethnicity/insurance predictor reflected the interaction between race–ethnicity and insurance: insured white (non-Hispanic), uninsured white, insured minority (Hispanic or black), or uninsured minority. Logistic and mixed-effects models adjusted for baseline BMI, age, gender, household income, HIV transmission category, antiretroviral therapy type, CD4+ count, plasma HIV-1 RNA, observation months, and visit frequency. Results:The cohort was 63% Hispanic and 14% black; 13.3% were insured white, 10.0% uninsured white, 40.9% insured minority, and 35.7% uninsured minority. At baseline, 37.5% were overweight, 22.1% obese. Median observation was 3.25 years. Twenty-four percent of the cohort had significant weight gain, which was more likely for uninsured minority patients than insured whites [adjusted odds ratio = 2.85, 95% confidence intervals (CIs): 1.66 to 4.90]. The rate of BMI increase in mixed-effects models was greatest for uninsured minorities. Of 455 overweight at baseline, 29% were projected to become obese in 4 years. Conclusions and Relevance:In this majority Hispanic HIV+ cohort, 60% were overweight or obese at baseline, and uninsured minority patients gained weight more rapidly. These data should prompt greater attention by HIV providers for prevention of obesity.

Cognitive efficiency is associated with endogenous cytokine levels in patients with chronic hepatitis C

The etiology of cognitive dysfunction in chronic hepatitis C (CHC) infection is unknown. Among the possibilities is cytokine activation, which has been associated with cognitive dysfunction in other chronic conditions. The purpose of this study was to investigate the relationship between endogenous IFN-alpha, IL-6, and TNF-alpha and cognitive functioning in CHC patients. Seventy-eight veterans with CHC underwent cognitive testing and measurement of serum cytokines. In patients with detectable IFN-alpha, higher levels of IL-6 and TNF-alpha were related to poorer cognitive functioning. Findings suggest CHC patients with immune responses characterized by elevated IFN-alpha may be at risk for cognitive difficulties.