Blood, tissue, and intracellular concentrations of azithromycin during and after end of therapy.

Although azithromycin is extensively used in the treatment of respiratory tract infections as well as skin and skin-related infections, pharmacokinetics of azithromycin in extracellular space fluid of soft tissues, i.e., one of its therapeutic target sites, are not yet fully elucidated. In this study, azithromycin concentration-time profiles in extracellular space of muscle and subcutaneous adipose tissue, but also in plasma and white blood cells, were determined at days 1 and 3 of treatment as well as 2 and 7 days after the end of treatment. Of all compartments, azithromycin concentrations were highest in white blood cells, attesting for intracellular accumulation. However, azithromycin concentrations in both soft tissues were markedly lower than in plasma both during and after treatment. Calculation of the area under the concentration-time curve from 0 to 24 h (AUC(0-24))/MIC(90) ratios for selected pathogens suggests that azithromycin concentrations measured in the present study are subinhibitory at all time points in both soft tissues and at the large majority of observed time points in plasma. Hence, it might be speculated that azithromycin's clinical efficacy relies not only on elevated intracellular concentrations but possibly also on its known pleotropic effects, including immunomodulation and influence on bacterial virulence factors. However, prolonged subinhibitory azithromycin concentrations at the target site, as observed in the present study, might favor the emergence of bacterial resistance and should therefore be considered with concern. In conclusion, this study has added important information to the pharmacokinetic profile of the widely used antibiotic drug azithromycin and evidentiates the need for further research on its potential for induction of bacterial resistance.

Blood, tissue, and intracellular concentrations of erythromycin and its metabolite anhydroerythromycin during and after therapy.

For macrolides, clinical activity but also the development of bacterial resistance has been attributed to prolonged therapeutic and subtherapeutic concentrations. Although erythromycin is a long-established antimicrobial, concomitant determination of the pharmacokinetics of erythromycin and its metabolites in different compartments is limited. To better characterize the pharmacokinetics of erythromycin and its anhydrometabolite (anhydroerythromycin [AHE]) in different compartments during and after the end of treatment with 500 mg of erythromycin four times daily, concentration-time profiles were determined in plasma, interstitial space of muscle and subcutaneous adipose tissue, and white blood cells (WBCs) at days 1 and 3 of treatment and 2 and 7 days after end of therapy. In WBCs, concentrations of erythromycin exceeded those in plasma approximately 40-fold, while free concentrations in plasma and tissue were comparable. The observed delay of peak concentrations in tissue might be caused by fast initial cellular uptake. Two days after the end of treatment, subinhibitory concentrations were observed in plasma and interstitial space of both soft tissues, while 7 days after the end of treatment, erythromycin was not detectable in any compartment. This relatively short period of subinhibitory concentrations may be advantageous compared to other macrolides. The ratio of erythromycin over AHE on day 1 was highest in plasma (2.81 ± 3.45) and lowest in WBCs (0.27 ± 0.22). While the ratio remained constant between single dose and steady state, after the end of treatment the concentration of AHE declined more slowly than that of the parent compound, indicating the importance of the metabolite for the prolonged drug interaction of erythromycin.

Translational, rotational, and vibrational coupling into phase in diffractively coupled optical cavities.

All-reflective optical systems are under consideration for future gravitational wave detector topologies. A key feature of these all-reflective systems is the use of Fabry-Perot cavities with diffraction gratings as input couplers; however, theory predicts and experiment has shown that translation of the grating surface across the incident laser light will introduce additional phase into the system. This translation can be induced through simple side-to-side motion of the coupler, yaw motion of the coupler around a central point (i.e., rotation about a vertical axis), and even via internal resonances (i.e., vibration) of the optical element. In this Letter we demonstrate on a prototype-scale suspended cavity that conventional cavity length-sensing techniques used to detect longitudinal changes along the cavity axis will also be sensitive to translational, rotational, and vibrational motion of the diffractive input coupler. We also experimentally verify the amplitude response and frequency dependency of the noise coupling as given by theory.

Population pharmacokinetic comparison and pharmacodynamic breakpoints of ceftazidime in cystic fibrosis patients and healthy volunteers.

Despite the promising activity of ceftazidime against Pseudomonas aeruginosa and Burkholderia cepacia, there has not yet been a study that directly compared the pharmacokinetics (PK) of ceftazidime in cystic fibrosis (CF) patients and healthy volunteers by population PK methodology. We assessed the population PK and PK/pharmacodynamic (PD) breakpoints of ceftazidime in CF patients and healthy volunteers. Eight CF patients (total body weight [WT] [average +/- standard deviation] = 42.9 +/- 18.4 kg) and seven healthy volunteers (WT = 66.2 +/- 4.9 kg) received 2 g ceftazidime as a 5-min intravenous infusion. High-performance liquid chromatography (HPLC) was used for drug analysis, and NONMEM (results reported), S-ADAPT, and NPAG were used for parametric and nonparametric population PK modeling. We considered linear and allometric body size models to scale clearance and volume of distribution. Monte Carlo simulations were based on a target time of non-protein-bound plasma concentration of ceftazidime above MIC of > or =65%, which represents near-maximal killing. Unscaled total clearance was 19% lower in CF patients, and volume of distribution was 36% lower. Total clearance was 7.82 liters/h for CF patients and 6.68 liters/h for healthy volunteers with 53 kg fat-free mass. Allometric scaling by fat-free mass reduced the between-subject variability by 32% for clearance and by 18 to 26% for volume of both peripheral compartments compared to linear scaling by WT. A 30-min ceftazidime infusion of 2 g/70 kg WT every 8 h (q8h) achieved robust (> or =90%) probabilities of target attainment (PTAs) for MICs of < or =1 mg/liter in CF patients and < or =3 mg/liter in healthy volunteers. Alternative modes of administration achieved robust PTAs up to markedly higher MICs of < or =8 to 12 mg/liter in CF patients for 5-h infusions of 2 g/70 kg WT q8h and < or =12 mg/liter for continuous infusion of 6 g/70 kg WT daily.

[Spontaneous rupture of a splenic artery]. / Idiopathische spontane Milzarterienruptur.

BACKGROUND: Hemoperitoneum due to spontaneous rupture of a visceral vessel may result from a variety of underlying pathologies. However, its idiopathic form does not show evidence of any predisposition. PATIENT AND METHODS: An abdominal CT scan for acute abdominal pain yielded the unexpected diagnosis of a ruptured splenic artery in a 21-year-old patient. Hemostasis was achieved by endovascular coiling of a segmental splenic artery lacking any evidence of pathological transformation. An extensive intraabdominal hematoma was evacuated in a consecutive laparoscopy which, furthermore, confirmed interventional success. Despite extensive diagnostic efforts, the cause of the bleeding remained undefined. CONCLUSION: Spontaneous hemoperitoneum may occasionally be considered as a cause of acute abdomial pain and is diagnostically challenging. An interdisciplinary approach is desirable to meet the objective of modern organ-preserving therapy in splenic artery rupture.

Pharmacokinetics, pharmacodynamics and tolerability of multiple oral doses of linagliptin, a dipeptidyl peptidase-4 inhibitor in male type 2 diabetes patients.

AIMS: To investigate the safety, tolerability, pharmacokinetic and pharmacodynamic properties of multiple oral doses of the dipeptidyl peptidase-4 (DPP-4) inhibitor linagliptin (BI 1356) in patients with type 2 diabetes mellitus. METHODS: Forty-seven male type 2 diabetic patients received linagliptin 1, 2.5, 5 or 10 mg, or placebo, once daily for 12 days. RESULTS: Linagliptin exposure [area under the plasma concentration-time curve and maximum plasma concentration (Cmax)] increased less than proportionally with dose. Accumulation half-life was short (8.6-23.9 h), resulting in rapid attainment of steady state (2-5 days) and little accumulation (range: 1.18-2.03). The long terminal half-life (113-131 h) led to a sustained inhibition of DPP-4 activity. Renal excretion was below 1% on day 1 in all dose groups. Inhibition of plasma DPP-4 activity correlated well with linagliptin plasma concentrations, resulting in DPP-4 inhibition >90% in the two highest dose groups; even 24 h postdose, DPP-4 inhibition was >80%. Following an oral glucose tolerance test, 24 h after the last dose, statistically significant reductions of glucose excursions were observed with linagliptin (2.5, 5 and 10 mg doses) compared with placebo. Linagliptin was well tolerated. The frequency of adverse events (AEs) was not higher with linagliptin (54%) than with placebo (75%). No serious AEs and no episodes of hypoglycaemia were reported. CONCLUSIONS: In type 2 diabetic patients, multiple rising doses of linagliptin were well tolerated and resulted in significant improvements of glucose parameters. Together with the favourable pharmacokinetics, these results confirm the unique profile of linagliptin in the DPP-4 inhibitor class.

Safety, tolerability, pharmacokinetics, and pharmacodynamics of single oral doses of BI 1356, an inhibitor of dipeptidyl peptidase 4, in healthy male volunteers.

This randomized, double-blind, parallel, placebo-controlled, single rising-dose study investigated the safety, tolerability, pharmacokinetic, and pharmacodynamic profiles of BI 1356 (once-daily, given orally) in healthy men. BI 1356 was well tolerated and safe up to and including a dose of 600 mg. The incidence of drug-related adverse events was equal in subjects receiving BI 1356 (30%) or placebo (31%). No clinically relevant deviations in laboratory or ECG parameters were reported. Exposure of BI 1356 increased less than proportionally from 2.5 mg to 5 mg, more than proportionally from 25 mg to 100 mg and approximately proportionally for doses from 100 mg to 600 mg. The geometric mean terminal half-life was up to 184 hours. Renal excretion was low. All doses of BI 1356 inhibited plasma dipeptidyl peptidase 4 activity. Single doses of 2.5 mg and 5 mg inhibited dipeptidyl peptidase 4 activity by 72.7% and 86.1% from baseline, respectively. The time to achieve maximum inhibition shifted with increasing doses from 3 hours (2.5 mg) to <0.7 hours (> or =200 mg). Within the dose range tested, a direct pharmacokinetic/pharmacodynamic relationship was observed. The pharmacokinetic and pharmacodynamic profile results demonstrate the potency and full 24-hour duration of action of BI 1356. Based on an estimated therapeutic dose of 5 mg, the therapeutic window of BI 1356 is expected to be >100-fold.

Optical modulation techniques for length sensing and control of optical cavities.

We present a discussion of the use of amplitude modulation techniques with regard to the length sensing and control of optical cavities for laser interferometric gravitational-wave detectors. Traditional radio-frequency amplitude modulation techniques automatically include phase modulation as a product of the modulation process, which can contaminate the signal after demodulation. In particular, with many length-sensing and control schemes the detected signals are demodulated in quadrature, which, in the case of a traditional amplitude modulation scheme, will result in offsets due to the additional phase modulation. We demonstrate this effect using a simple optical cavity configuration and show that minor adjustments to the modulator system can be used to compensate for the extra modulation components and provide additional flexibility.

[Minimal Change Glomerulonephritis]. / Minimal Change Glomerulonephritis.

We report two cases of minimal change glomerulonephritis (synonyms: idiopathic nephrotic syndrom, minimal change disease). A 47-year old female patient was admitted to our unit with a relapsing nephrotic syndrome since childhood. Another patient, a 22-year old female, presented with moderately swollen legs that developed over several months and a complaint of frequent upper respiratory tract infections during the last year. In both cases we suspected a minimal change glomerulonephritis which can only be proven by renal biopsy. Therapeutic options comprise steroids, cyclosporin, tacrolimus or even cyclophosphamide, depending on the clinical presentation of the disease in the individual case.

[CT-guided sympathicolysis in peripheral artery disease - Indications, patient selection and long-term results]. / CT-gesteuerte Sympathikolyse bei peripherer arterieller Verschlusskrankheit - Indikationen, Patientenauswahl, Langzeitergebnisse.

PURPOSE: Assessment of long-term results of CT-guided lumbar sympathicolysis (LSL) in advanced peripheral arterial vascular disease (pavd). Establishment of a suitable patient selection. PATIENTS AND METHODS: LSL was performed in 138 cases with Fontaine stages III (13 %) and IV (87 %). 250 consecutive patients were examined with a radionuclide perfusion study of the feet prior to and during peridural anaesthesia (PDA) in order to select suitable patients for LSL. LSL was not performed in patients with impaired perfusion under PDA (n = 112). Early and long-term results after one to five years were evaluated. RESULTS: In 79 % an initial improvement was found after LSL. After more than one year success was established in 38 %. 49 % of the cases had a progression of the disease. This is significantly better compared to a control group with conservative treatment and an initial improvement of 36 %. After more than one year only12 % revealed an improvement. In 82 % the disease was progressive. Diabetics showed also a positive response to LSL. CONCLUSION: LSL has a positive influence on the course of pvad in patients selected by radionuclide perfusion studies. Diabetes and angiographic findings do not play any first role in patient selection for LSL.

Current practice of temporary vena cava filter insertion: a multicenter registry.

PURPOSE: To evaluate the current practice of temporary vena cava filter placement and its complications. MATERIALS AND METHODS: A multicenter registry was conducted from May 1995 until May 1997 using a standardized questionnaire. One hundred eighty-eight patients were evaluated. Patient characteristics, filter indications, filter characteristics, and complications were registered. RESULTS: Deep vein thrombosis was proven in 95.2% of the patients. Main filter indication was thrombolysis therapy (53.1%). Average filter time was 5.4 days. An Antheor filter was inserted in 56.4%, a Guenther filter in 26.6%, and a Prolyser filter in 17.%. Transfemoral filter implantation was slightly preferred (54.8%). Four patients died of pulmonary embolism (PE) during filter protection. Major filter problems were filter thrombosis (16%) and filter dislocation (4.8%). When thrombus was found in or at the filter before explantation, additional thrombolysis was performed in 16.7%, additional filter implantation in 10%, and thrombus aspiration in 6.7%; 4.8% of filters were replaced with permanent filters. DISCUSSION: Temporary vena cava filters are placed to prevent PE in a defined patient population. Despite their presence, PEs still occur in a small percentage. Problems of filter thrombosis and dislocation have to be solved. CONCLUSION: The results of this multicenter registry support the need for innovative filter design, as well as a randomized, prospective study.

Gene cloning and sequencing, and enzyme purification of the malate synthase of Streptomyces arenae.

Streptomyces arenae is able to grow on acetate or ethanol as the sole carbon source. The metabolic pathway used for gluconeogenesis from C2 compounds in streptomycetes has not yet been characterized. In the course of a sequencing project we identified the gene for malate synthase (aceB), a key enzyme in the glyoxylate cycle in S. arenae. The gene was cloned and sequenced. The open reading frame of 1632 bp codes for a potential protein of 61.360 kDa. A comparison with the sequences of malate synthase from other organisms shows that the phylogenetic distance to the E. coli aceB gene is no closer than that to genes from plants or fungi. Malate synthase activity was detected in cell extracts from S. arenae. Its dependence on media conditions and on the growth phase was investigated. A purification procedure was established which allows a 188-fold enrichment of the enzyme. The molecular weight of the monomer determined by SDS PAGE confirms the weight calculated from the gene sequence. However, the holoenzyme appears to be dimeric as shown by gel filtration. All other known malate synthases from eubacteria are monomeric, while those of fungi or plants are oligomeric (di-, tri-, tetra- or octameric). The apparent Km value for glyoxylate is significantly higher than that of the malate synthases of all other species published so far. The enzyme is inactive at pH values of 7 and below; the strain cannot grow on ethanol or acetate as the sole carbon source at media pH values of 7 or below.

Flow cytometric detection of activation-induced cell death (apoptosis) in peripheral blood lymphocyte subpopulations from healthy cats.

Human peripheral blood lymphocytes (PBLs) from healthy individuals are resistant to in vitro-induced apoptosis, but activated human lymphocytes can readily undergo apoptosis. The activation of human lymphocytes is accompanied by the upregulation of a cell surface antigen, the major histocompatibility complex (MHC) class II-antigen. Only a minority of PBLs are usually MHC class II-antigen-positive in healthy humans. In contrast, in healthy cats the majority of feline PBLs are MHC class II-antigen-positive. We have, therefore, investigated the sensitivity of feline peripheral blood lymphocytes obtained from specified pathogen free (SPF) cats to the induction of apoptosis. Feline PBLs from SPF cats (n = 16) and human PBLs from healthy donors (n = 2) were isolated. After short-term culture, cells were examined for the presence of fragmented DNA as a result of apoptosis by a DNA agarose gel electrophoresis method and for the presence of DNA double strand breaks by in situ 3' end labeling. In addition, relative DNA content per cell was flow cytometrically determined using propidium iodide (PI) or 7-actinomycin-D (7-AAD) and apoptotic cells were identified on the basis of a reduced DNA content. Cell surface antigens and cellular DNA were analyzed simultaneously by dual-color flow cytometric analyses in order to study lymphocyte subsets. Single- and dual-color analysis revealed that, in contrast to human lymphocytes, feline lymphocytes rapidly underwent apoptosis when cultured overnight in medium. Furthermore, the majority of apoptotic cells was found within the MHC II-positive cell subject.

T-cell death by apoptosis in vertically human immunodeficiency virus-infected children coincides with expansion of CD8+/interleukin-2 receptor-/HLA-DR+ T cells: sign of a possible role for herpes viruses as cofactors?

One mechanism proposed to play a role in T-cell depletion in human immunodeficiency virus (HIV) infection is apoptosis (activation-induced cell death). We assessed whether apoptosis is related to activation of T cells in vivo and its possible triggers. DNA was extracted from peripheral blood mononuclear cells (PBMC) taken from 16 vertically HIV-infected children and 9 HIV-negative children born to HIV-positive mothers (controls) and tested by agarose gel electrophoresis for the presence of DNA fragments specific for apoptosis. Signs of apoptosis were found on in vitro culture of PBMC from 12 of 16 HIV-infected children, but not in PBMC from the nine controls. Eleven of the 12 HIV-infected children with apoptosis showed an elevated (> 15%) proportion of CD3+/HLA-DR+ cells. This was due to an increased proportion of CD8+/HLA-DR+ cells, as shown in 7 of 7 further tested patients. In none of the probands an increased (> 5%) proportion of IL-2 receptor expressing CD3+ cells was found. T cells undergoing apoptosis were preferentially of the CD8+ phenotype. Expansion of circulating CD8+/interleukin-2 receptor (IL-2R)-/HLA-DR+ T cells is known to occur during active infection with herpes viruses. To investigate the possible role of herpes viral coinfections for apoptosis in HIV infection, we focused on Epstein-Barr virus (EBV) as an example for a herpes virus usually acquired during childhood. In 10 of 12 patients with apoptosis, we found increased levels of EBV genome in PBMC and/or tissues, indicating active EBV replication. By contrast, no increased burden of EBV was found in the four HIV-infected patients without apoptosis or in the controls. Our data indicate that in children the occurrence of apoptosis in HIV infection is closely related to activation of CD8+ T cells. Furthermore, primoinfection with or reactivation of herpes viruses, such as EBV, may substantially contribute to such T-cell activation and the ensuing apoptosis. Additional studies are warranted to evaluate the contribution of herpes virus-triggered apoptosis to the T-cell loss leading to the acquired immunodeficiency syndrome.