Valvular interstitial cells express angiotensinogen and cathepsin D, and generate angiotensin peptides

Cells capable of de novo angiotensin (Ang)II generation in the heart remain unidentified. High-density angiotensin converting enzyme (ACE) binding has been localized to sites of high collagen turnover, such as heart valve leaflets and their valvular interstitial cells (VIC). VIC express ACE mRNA and their membrane-bound ACE utilizes AngI as substrate. Whether VIC also express angiotensinogen (Ao) and an aspartyl protease, and whether they generate AngI and II de novo, is presently unknown. We sought to address these questions in serum-deprived cultured VIC. Ao, renin and cathepsin D (Cat-D) mRNA expression was addressed by RT-PCR. Production of Ao, AngI and AngII peptides were measured in VIC-culture media by radioimmunoassay (RIA). Immunoreactive Cat-D was detected by immunofluorescein labeling and Western blotting. Cat-D and renin activities were determined by spectrofluorometric and autoradiographic methods and AngI generation by RIA. Results showed (a) expression of Ao and Cat-D both at mRNA and protein levels; (b) AngI and AngII peptides in culture media; (c) acceleration of AngII production by exogenous AngI (1 nmol/l), which was blocked by lisinopril (0.1 mumol/l); (d) that dexamethasone (0.1 mumol/l) increased AngII production; (e) a 46 kDa immunoreactive Cat-D protein by Western blotting; (f) aspartyl protease activity, using chromogenic and 125I-labeled Ao as substrates, inhibited by pepstatin-A; and (g) the absence of renin mRNA and activity. It is concluded that at both the mRNA and protein levels, cultured VIC express Ao and Cat-D, and can generate AngI and AngII peptides by the action of a non-renin protease Cat-D and ACE, respectively. VIC therefore appear to represent a constitutive nonendothelial cell found in adult rat heart valve leaflets, which are capable of de novo Ang peptide generation.     

Determination of dioxins (PCDDs/PCDFs) and PCBs in food and feed using the DR CALUX® bioassay: Results of an international validation study

Maximum levels for dioxins in food and feedstuffs have been recently established by the European Commission through two regulations. Dioxin-monitoring programmes of food and feedstuffs will therefore be undertaken by the European Member States to implement these regulations, which would be facilitated by fast and low-cost screening methods. Commission Directives 2002/70/EC and 2002/69/EC describe specific characteristics for such screening methods. In the present study, the performance characteristics of the DR CALUX® method from BioDetection Systems were established in a validation study with 14 participants. The study was based on two materials (fish oil and feed), each containing four different levels of dioxins and dioxin-like PCBs around the current limits. The results demonstrate that the test is very promising but that in particular the clean-up procedure was a source of variation and requires further optimization and standardization. In addition the quantification is improved by the use of control samples to correct for background contamination, recovery and differences between the TEF values and REP (relative potency) factors in the test.     

Tamoxifen and toremifene concentrations in plasma are greatly decreased by rifampin

BACKGROUND: Rifampin (INN, rifampicin) is a potent inducer of cytochrome P450 (CYP) enzymes involved in drug metabolism and therefore causes many drug interactions. METHODS: The effects of rifampin on the pharmacokinetics of tamoxifen (study I) and toremifene (study II) were examined in 2 randomized, placebo-controlled crossover studies. Ten (study I) or 9 (study II) healthy male volunteers took either 600 mg rifampin or placebo orally once a day for 5 days. On the sixth day, 80 mg tamoxifen or 120 mg toremifene was administered orally. Blood samples were collected up to 336 hours after drug administration. RESULTS: Rifampin reduced the area under the plasma concentration-time curve (AUC) of tamoxifen by 86% (P < .001), peak plasma concentration (Cmax) by 55% (P < .001), and elimination half-life (t1/2) by 44% (P < .001). The AUC of toremifene was reduced by 87% (P < .001), Cmax by 55% (P < .001), and t1/2 by 44% (P < .01) with rifampin. During the rifampin phase, the AUC of N-demethyltamoxifen was 38% (P < .001) and the AUC of N-demethyltoremifene was 20% (P < .01) of that during the placebo phase. CONCLUSIONS: Rifampin markedly reduces the plasma concentrations of tamoxifen and toremifene by inducing their CYP3A4-mediated metabolism. Concomitant use of rifampin or other potent inducers of CYP3A4 with tamoxifen and toremifene may reduce the efficacy of these antiestrogens.     

Laparoscopic fimbrioplasty: an evaluation of 35 cases

The aim of this prospective study was to assess the value of laparoscopic treatment of severe fimbrial occlusions. During a period of 52 months infertile patients with fimbrial lesions were treated by operative laparoscopy. Only those patients requiring incision of the tubal serosa (salpingostomy) were included, representing the most severe lesions. The most frequent cases, those patients requiring simple adhesiolysis and deagglutination of the fringes, were excluded. All tubal lesions were documented carefully. Positive Chlamydia trachomatis (CT) serology was found in 65.7% of the patients. All the patients were followed up for at least 2 years. Three patients lost to follow-up were defined as failures. The global conception rate was 74.3%. The intrauterine pregnancy rate was 51.4%, and the 'take home baby rate' was 37.1% (only the first pregnancy being taken into account). The ectopic pregnancy rate was 22.9%. A positive CT serology was found to have a significant influence on the outcome. It can be concluded that the laparoscopic approach provides results similar to those obtained by microsurgery for the treatment of severe fimbrial occlusions, and represents an acceptable alternative to in-vitro fertilization (IVF) in selected cases.     

Neurturin exerts potent actions on survival and function of midbrain dopaminergic neurons

Glial cell line-derived neurotrophic factor (GDNF) exhibits potent effects on survival and function of midbrain dopaminergic (DA) neurons in a variety of models. Although other growth factors expressed in the vicinity of developing DA neurons have been reported to support survival of DA neurons in vitro, to date none of these factors duplicate the potent and selective actions of GDNF in vivo. We report here that neurturin (NTN), a homolog of GDNF, is expressed in the nigrostriatal system, and that NTN exerts potent effects on survival and function of midbrain DA neurons. Our findings indicate that NTN mRNA is sequentially expressed in the ventral midbrain and striatum during development and that NTN exhibits survival-promoting actions on both developing and mature DA neurons. In vitro, NTN supports survival of embryonic DA neurons, and in vivo, direct injection of NTN into the substantia nigra protects mature DA neurons from cell death induced by 6-OHDA. Furthermore, administration of NTN into the striatum of intact adult animals induces behavioral and biochemical changes associated with functional upregulation of nigral DA neurons. The similarity in potency and efficacy of NTN and GDNF on DA neurons in several paradigms stands in contrast to the differential distribution of the receptor components GDNF Family Receptor alpha1 (GFRalpha1) and GFRalpha2 within the ventral mesencephalon. These results suggest that NTN is an endogenous trophic factor for midbrain DA neurons and point to the possibility that GDNF and NTN may exert redundant trophic influences on nigral DA neurons acting via a receptor complex that includes GFRalpha1.     

The binding protein for globular heads of complement C1q, gC1qR. Functional expression and characterization as a novel vitronectin binding factor

A binding protein for the globular head domains of complement component C1q, designated gC1qR, recently described to be present on vascular and blood cells (Ghebrehiwet, B., Lim, B.-L., Peerschke, E. I. B., Willis, A. C., and Reid, K. B. M. (1994) J. Exp. Med. 179, 1809-1821 was expressed in recombinant form in bacteria to investigate its functional and structural properties. The recombinant gC1qR was found to be functional because tetramerization of the 24.3-kDa polypeptide occurred as described for the native protein, and the binding of the ligand C1q by recombinant gC1qR was indistinguishable from binding shown by gC1qR isolated from Raji cells. Recombinant gC1qR immobilized to microspheres was used to search for additional binding proteins unrelated to C1q. Surprisingly, it was found that vitronectin or complexes containing vitronectin were retained from plasma or serum, and subsequent analysis revealed the specific binding of the ternary vitronectin-thrombin-antithrombin complex to gC1qR. Because the thrombin-antithrombin complex was unable to interact with gC1qR, direct binding with vitronectin was investigated in a purified system. The heparin binding multimeric form of vitronectin but not the plasma form of vitronectin was found to bind specifically to gC1qR isolated from Raji cell membrane as well as to recombinant gC1qR. This interaction was saturable (KD approximately 20 nM) and inhibitable by glycosaminoglycans such as heparin but not by chondroitin sulfate. C1q and vitronectin did not compete with each other for binding to gC1qR, and both ligands seem to interact with different parts of the gC1qR because a truncated version of recombinant gC1qR lacking the N-terminal 22-amino acid portion hardly interacted with vitronectin but bound C1q as well as the intact gC1qR. These findings establish gC1qR as a novel vitronectin-binding protein that may participate in the clearance of vitronectin-containing complexes or opsonized particles or cooperate with vitronectin in the inhibition of complement-mediated cytolysis.     

Microbial growth control in water hydraulic systems by conventional filtration

As a service to readers who understand German, French or Spanish better than English, the abstract of the research article in this issue follows in these languages.     

A comparison of 2 modes of administration of recombinant interleukin-2: continuous intravenous infusion alone versus subcutaneous administration plus interferon alpha in patients with advanced renal cell carcinoma

PURPOSE: To compare 2 treatment modalities with recombinant Interleukin-2 (rIL-2) for patients with advanced Renal Cell carcinoma (RCC): continuous intravenous infusion (CIV) alone versus subcutaneous (s/c) rIL-2 + Interferon-alpha (IFN-alpha). PATIENTS AND METHODS: Data have been collected on 425 patients with RCC, treated CIV rIL-2 alone, (225 patients), or rIL-2 by the s/c route (200 patients). Patients receiving s/c rIL-2 also received s/c IFN-alpha both drugs being administered on an outpatient basis. Patients receiving CIV rIL-2 were treated as inpatients. Patient eligibility criteria were similar on all studies, and included patients with progressive, advanced disease, but with an ambulatory performance status. RESULTS: The overall response rate for the CIV schedules was not significantly different from the s/c regimens: 15% (95% confidence limits (CL) 10-20%) vs 20% (95%CL 14-26%) with 4% CR in both approaches. Durable responses were seen in both CIV and s/c schedules and there was no evidence of a significant difference in survival in multivariate analysis. There was however an important shift in the toxicity profile. The s/c regimens do not induce a clinically detectable capillary leak syndrome, which is the dose limiting toxicity for CIV regimens. CONCLUSION: Although the introduction of CIV regimens of rIL-2 was a major step forward compared to high-dose bolus, because most patients could be treated in a normal oncology ward, the s/c schedule of rIL-2 + IFN-alpha offers the possibility of outpatient (home) therapy, with no evidence of a reduction in efficacy.