Natural killer (NK) cell function is likely to be important in controlling HIV infection and opportunistic pathogens. We therefore evaluated NK function and phenotype over the course of antiretroviral therapy (ART) and examined the potential mechanisms of altered NK activity in HIV infection.

To assess the influence of the CYP3A4 enzyme inducer rifampin on the pharmacokinetics of the immunosuppressant everolimus to provide guidance for their coadministration.

A proposed model of thrombopoietin (TPO) regulation is that of a constitutive production of TPO with circulating levels being predominately regulated by changes in platelet and megackaryocyte mass. Using a pharmacodynamic (PD) approach, the authors examined the validity of this model for patients with acute myeloid leukemia (AML) undergoing dose-intensive postinduction chemotherapy (HDT). TPO and platelet values were assayed weekly in AML patients undergoing HDT. A parsimonious dynamic model was then applied to these experimental data. The results (1) support the proposed model of TPO regulation, (2) model and quantify the effects of HDT on the megakaryocyte compartment, (3) characterize variables not amenable to direct measurement, and (4) have clinical utility as this model predicted that TPO given after HDT would not have a significant effect on platelet recovery, a finding borne out in clinical trials. This model provides information relevant to the interpretation of clinical trials of hematopoietic growth factors.

Angiotensin II (Ang II) type 1 receptor (AT(1)) antagonists such as losartan (LOS) are widely used for the treatment of hypertension and elicit antiinflammatory and antiaggregatory in vitro and in patients, although the underlying mechanism are unclear. Following computer-based molecule similarity, we proposed that on cytochrome-P450 degradation, the LOS metabolite EXP3179 is generated, which shows molecule homology to indomethacin, a cyclooxygenase inhibitor with antiinflammatory and antiaggregatory properties. Subsequently, serum-levels of EXP3179 were determined for 8 hours in patients receiving a single oral dose of 100 mg LOS. High-performance liquid chromatography followed by liquid chromatography-mass spectrometry (GC-MS) [corrected] from serum samples revealed a maximum of 10(-7) mol/L for EXP3179 peaking between 3 to 4 hours. The increase in serum-EXP3179 levels was associated with a significant reduction in platelet aggregation in vivo (-35+/-4%, P<0.001 versus control). EXP3179 generation was investigated in a chemical reaction mimicking the liver cytochrome-P450-dependent LOS-degradation and human endothelial cells were exposed to Ang II or lipopolysaccharides (LPS) in the presence of EXP3179 (10(-7) mol/L). LPS- and Ang II-induced COX-2 transcription was abolished by EXP3179. Moreover, EXP3179 significantly reduced Ang II- and LPS-induced formation of prostaglandin F2alpha as determined by GC-MS [corrected]. Thus, antiinflammatory properties of LOS are mediated via its EXP3179 metabolite by abolishing COX-2 mRNA upregulation and COX-dependent TXA2 and PGF2alpha generation. Serum levels of EXP3179 are detectable in patients in concentrations that exhibit antiinflammatory and antiaggregatory properties in vitro.

Neutralizing antibodies (NAB) to interferon beta (IFNbeta) occur in some multiple sclerosis (MS) patients, particularly during the first year of treatment. The presence of NAB may be associated with an attenuation of the therapeutic effect. The aim of this study was to compare the frequency of NAB occurrence in patients treated with IFNbeta-1 b with that in patients treated with IFNbeta-1 b combined with monthly pulses of intravenous methylprednisolone (MP). One hundred and sixty-one patients with relapsing-remitting MS were randomized in two treatment arms: 8 MIU of IFNbeta- 1 b subcutaneously injected every other day either alone or in combination with 1000 mg of monthly intravenous MP. NAB were evaluated at baseline and at months 3,6,9,12 and 15 by the MxA assay in a specialized laboratory. Positivity was defined as a titer of > or = 20 neutralizing units according to two different definitions: I) one or more non-consecutive positive samples, II) at least two consecutive positive samples. NAB (definition I) were observed in 26.8% of patients in the IFNbeta-1 b alone arm and in 12.1% of patients in the combination therapy arm (p = 0.05 by the chi-square test), which corresponds to a relative reduction of 54.9%, whereas according to definition II, these figures dropped to 22.5 % for the IFNbeta-1 b alone arm, and 10.6% for the combination therapy arm (relative reduction 52.9%, p = 0.10, NS). A higher probability of remaining in the NAB-free status was observed in patients treated with the combination therapy (p = 0.031 for definition I and p = 0.o49 for definition II, by the Wilcoxon-Gehan test). Methylprednisilone combined with IFNbeta-1 b reduces the incidence of neutralizing bodies to in terferon-beta during the first year of treatment in MS patients.

A role for serotonin in season affective disorder (SAD) has been explored with a variety of serotonergic pharmacologic agents. The authors initially hypothesized that metergoline, a nonspecific serotonin antagonist, would exacerbate depressive symptoms. In a small, open-label pilot study, the authors observed the opposite effect. They decided to follow up on this finding with this formal study. The study followed a double-blind, randomized cross-over design. Sixteen untreated, depressed patients with SAD received single oral doses of metergoline 8 mg and of placebo, spaced 1 week apart. Fourteen patients were restudied after 2 weeks of light treatment. Depression ratings using the Structured Interview Guide for the Hamilton Depression Rating Scale-Seasonal Affective Disorder Version were performed at baseline and at 3 and 6 days after each intervention. These data were analyzed by baseline-corrected repeated measures with analysis of variance. In the off-lights condition, severity of depression was diminished after metergoline compared with placebo administration (p = 0.001). Patient daily self-ratings suggested that the peak effect occurred 2 to 4 days after study drug administration. In contrast, after 2 weeks of treatment with bright artificial light, metergoline did not demonstrate a significant effect on mood. These data suggest that single doses of metergoline may have antidepressant effects that last several days. Possible mechanisms include 5-hydroxytryptamine(2) receptor downregulation and dopamine agonism.

Neurohormonal activation in children with heart failure due to congenital heart disease leads to downregulation of myocardial beta-receptors that may influence the postoperative course after cardiothoracic surgery.

To determine the effect of a single dose of mifepristone (200 mg) on endometrial estrogen and progesterone receptors in Norplant users.

It was shown that the 3-month supplementation of patients having colon polyps with folic acid (5 mg/day) led to a 35% decrease in abnormally high ornithine decarboxylase activity in polyps that was accompanied by a 43% increase of S-adenosylmethionine content in polyps.

To investigate the mechanism of prolonged uterine hemorrhage after terminating early pregnancy by mifepristone plus misoprostol.

Megestrol acetate improves appetite and abrogates weight loss in some patients with advanced cancer. Moreover, preliminary studies suggest that progestational agents down-regulate interleukin-6 (IL-6), an inflammatory cytokine widely implicated in cancer-associated anorexia and weight loss. The present investigation examined the effects of megestrol acetate on IL-6 in an attempt to confirm these earlier, preliminary studies. The translational component of a large multi-institutional trial, this investigation examined 85 patients with advanced cancer and weight loss. Patients had been randomly assigned to receive megestrol acetate liquid suspension 800 mg/day + placebo tablets, or oral dronabinol tablets 2.5 mg b.i.d. + liquid placebo, or both agents. Other testing included serial physician-reported weight and patient-reported appetite and global quality of life. We found no significant differences in 1-month changes in serum IL-6 according to whether patients had been treated with megestrol acetate, dronabinol, or the combination: the mean differences +/- standard deviation were -1.52+/-4.7 pg/ml, -0.62+/-3.5 pg/ml, and -0.2+/-3.1 pg/ml, respectively (P=0.40, by one-way ANOVA). Among the patients who noted alterations in their appetite over 1 month, we observed no significant changes in IL-6. Finally, changes in serum IL-6 were not associated with shifts in weight or global quality of life. Our investigation provides no evidence that megestrol acetate down-regulates IL-6 in patients with cancer-associated anorexia and weight loss.

Functional foods enriched with plant stanols lower atherogenic LDL cholesterol concentrations. This effect is caused at least partly by a decreased intestinal cholesterol absorption. It has been suggested that LDL production is reduced after plant stanol consumption, but it is unknown whether LDL receptor expression is affected and contributes to the LDL-lowering effect of plant stanols. Markers for endogenous cholesterol synthesis (lathosterol) increase, but it is not known how this higher cholesterol synthesis is regulated at the molecular level. In a double-blind placebo controlled trial, we have found that compared with the control group (N=15), daily consumption of 3.8-4.0 g plant stanol esters (N=29) for 8 weeks increased LDL receptor mRNA levels in human mononuclear blood cells by 43% (P=0.003). LDL receptor protein concentrations on the surface of monocytes and T lymphocytes increased by 37% (P=0.003) and 25% (P=0.013), suggesting an increased translation. This increased protein expression appeared to be functional, since changes in serum LDL cholesterol correlated negatively with changes in LDL receptor mRNA levels (r=-0.361; P=0.015) and changes in LDL receptor protein expression in monocytes (r=-0.440; P<0.001) and T lymphocytes (r=-0.307; P=0.018). Based on these results, we suggest that the higher LDL receptor expression contributed to a lowered LDL formation along the apoB cascade. Whole body cholesterol synthesis increased, as indicated by the rise in serum cholesterol-standardized lathosterol concentrations, but the 34% increased HMG-CoA reductase mRNA concentrations did not reach statistical significance. Nor did it correlate significantly with changes in serum cholesterol-standardized lathosterol concentrations. This suggests that HMG-CoA reductase may be only partly regulated at a transcriptional level.

There is accumulating evidence that theophylline has anti-inflammatory or immunomodulatory effects. This may be, in part, mediated via an upregulation in the production of the anti-inflammatory cytokine interleukin (IL)-10. We determined whether low-dose theophylline (LDT) would increase the production of IL-10, and attenuate the production of proinflammatory cytokines by alveolar macrophages.

The present investigation tests the clinical hypothesis that Leydig-cell responsiveness to pulsatile and midphysiological LH drive is impaired in older men. To this end, we implemented a novel clinical investigative paradigm consisting of preadministration of an LH-down-regulating dose (3.75 mg) of leuprolide acetate followed, 3-4 wk later, by controlled challenge of the testis, with pulsatile iv infusions of saline vs. recombinant human (rh) LH. Based on a preliminary dose-finding experiment, we evaluated LH action in 8 young (ages, 18-25 yr) and 7 older (ages, 60-85 yr) volunteers by infusing eight consecutive 6-min squarewave pulses of saline or 50 IU rhLH iv every 2 h. Analyses were carried out 48 or 72 h apart in a prospective, randomly assigned, double-blind, within-subject cross-over design. Serum concentrations of T (RIA) and LH (immunoradiometric assay) were measured in blood sampled every 10 min concurrently. Leuprolide injection suppressed pre-LH-infusion (0800 h baseline) serum T concentrations (pooled mean +/- SEM) markedly in both age groups (P < 10(-3)); namely, to 40 +/- 20 ng/dl (young) and 12 +/- 3.1 ng/dl (older; P < 0.05 vs. young) (to convert to nM, multiply by 0.0347). Successive iv pulses of rhLH stimulated T output, over time, to an asymptotic maximum of 166 +/- 42 ng/dl in young men (P = 0.0008 vs. saline) and 57 +/- 9.8 ng/dl in older subjects (P = NS vs. saline, and P < 0.05 vs. young). Further regression analyses identified significant reductions of both the initial rate and maximum of the time-dependent incremental rise in LH-driven serum T concentrations in older men. In contrast, infused serum LH concentrations, distribution volumes, and calculated LH half-lives were comparable in the two age cohorts. We conclude that older men manifest both a delayed initial and reduced maximal serum T concentration rise compared with young men exposed to identical controlled midphysiological pulsatile LH drive.

Growth hormone (GH), insulin-like growth factor I (IGF-I), and testosterone (T) are important mediators of muscle protein synthesis, and thus muscle mass, all of which decline with age. We hypothesized that circulating hormones would be related to the transcriptional levels of their respective receptors and that this expression would be negatively related to expression of the myostatin gene. We therefore determined content of mRNA transcripts (by RT-PCR) for GH receptor (GHR), IGF-I, androgen receptor (AR), and myostatin in skeletal muscle biopsy samples from 27 healthy men >65 yr of age. There were no significant relationships between age, lean body mass, or percent body fat and transcript levels of GHR, IGF-I, AR, or myostatin. Moreover, there were no significant correlations of serum GH, IGF-I, or T with their corresponding target mRNA levels (GHR, intramuscular IGF-I, or AR) in skeletal muscle. However, GHR was negatively correlated (r = -0.60, P = 0.001) with myostatin mRNA levels. The lack of apparent relationships of muscle transcripts with their respective ligands in healthy older adults suggests that age-related deficits in both GH and T may lead to an increase in myostatin expression and a disassociation in autocrine IGF-I effects on muscle protein synthesis, both of which could contribute to age-related sarcopenia.

Based on an in vitro study and an uncontrolled in vivo trial we examined the effects of indomethacin on the expression of L-selectin by leukocytes in healthy volunteers. Eight subjects received infusions of 0.7 mg/kg indomethacin and placebo t.i.d. (three times daily) in a randomized, controlled trial. Indomethacin decreased the mean fluorescence intensity of the L-selectin expression on isolated neutrophils incubated with toxic indomethacin concentrations. However, indomethacin did not lower the L-selectin expression in whole blood or in-vivo. Thus, therapeutic doses of the cyclo-oxygenase inhibitor indomethacin do not lower the L-selectin expression on leukocytes. Hence, the inhibition of cyclo-oxygenase cannot explain the previously observed dexamethasone-induced decrease in L-selectin.

Interferon-beta reduces clinical exacerbations in multiple sclerosis (MS) through several immunomodulatory mechanisms that may involve augmentation of programmed cell death (apoptosis) of T lymphocytes. The anti-apoptosis protein FLIP (Fas-associated death domain-like interleukin-1beta-converting enzyme inhibitory protein) has been recently identified as a potent regulator of T lymphocyte susceptibility to apoptosis. In a prospective study, we evaluated the expression of FLIP and other apoptosis regulatory proteins in ex vivo activated T lymphocytes from MS patients, before and serially after treatment with interferon-beta. We also investigated the long-term effects of interferon-beta on T cell apoptosis in a cross-sectional study of MS patients receiving chronic drug therapy. Treatment with interferon-beta reduced the expression of FLIP isoforms in activated T lymphocytes. This reduced expression correlated with augmented T cell susceptibility to apoptosis and with clinical response to treatment. In contrast, interferon-beta therapy did not alter cellular expression of the anti-apoptotic protein Bcl-2. This downregulatory effect of interferon-beta on cellular FLIP expression was maintained following long-term therapy. Our findings suggest that interferon-beta therapy exerts a regulatory effect on peripheral T lymphocytes through a pro-apoptosis mechanism that involves the downregulation of cellular FLIP expression.

St John's wort (Hypericum perforatum) is a popular over-the-counter dietary supplement and herbal remedy that has been implicated in drug interactions with substrates of several cytochrome P450 (CYP) isozymes. The effect of St John's wort on CYP activity in vivo was examined with a probe drug cocktail.

The influence of 3-month interferon-alpha (IFN-alpha) treatment on plasma erythropoietin (EPO) concentration in patients with chronic active hepatitis (CAH) induced by hepatitis B virus (HBV) infection was investigated. The study was carried out in 44 nonanemic patients divided into two groups: CAH B, 30 subjects not treated with IFN-alpha, and CAH B-IFN, 14 subjects treated with IFN-alpha for the first 3 months of the study (5 MU/m(2) body surface subcutaneously (s.c.) three times per week). In all patients, blood samples were taken at the beginning of the study (0) and after 1, 2, 3, 6, 9, and 12 months of observation. At the beginning, plasma EPO levels in the CAH B (27.8 +/- 2.21 mU/ml) and CAH B-IFN (27.3 +/- 3.04 mU/ml) groups did not differ significantly from each other and were significantly higher (p < 0.0001) than in healthy subjects (10.4 +/- 1.06 mU/ml). In patients in the CAH B group, plasma EPO concentrations did not change significantly during the whole observation period. In patients in the CAH B-IFN group, a transient, significant increase in plasma EPO level was found. The highest plasma EPO concentration in this group was noted after the third month of treatment (41.1 +/- 3.41 mU/ml). In conclusion, patients with CAH induced by HBV infection are characterized by increased plasma EPO concentrations, and IFN-alpha treatment in these patients causes a transient increase in the plasma EPO level.

In two studies, the effects of the potentially interacting drugs mirtazapine and carbamazepine on their pharmacokinetics have been investigated. Subjects were treated with carbamazepine combined with placebo for 21 days and subsequently with carbamazepine combined with mirtazapine for another 7 days (Study A) or with mirtazapine combined with placebo for 7 days and subsequently mirtazapine combined with carbamazepine for another 21 days (Study B). Pharmacokinetic results indicate that carbamazepine decreased significantly AUC and Cmax values for mirtazapine and increased values for demethyl-mirtazapine Cmax. Mirtazapine had no effect on carbamazepine pharmacokinetic parameters, but did lower carbamazepine-10,11-epoxide levels. Mirtazapine did not affect the single dose kinetics or the enzyme inducing properties of carbamazepine. VAMRS alertness scores reflected the somnolence-inducing effects of carbamazepine and mirtazapine and psychometric test results revealed impairment of specific tasks. The combination was safe and routine laboratory testing did not reveal clinically relevant abnormalities. The dose of mirtazapine in patients on carbamazepine may have to be increased for optimal antidepressant efficacy.