Heterogeneity of binding sites for ICI 198,615 in human lung parenchyma.

We have identified and characterized two different subclasses of binding site for the novel peptido-leukotriene (LT) antagonist, [3H]ICI 198,615, in membranes from human lung parenchyma using a receptor-ligand assay. This novel compound is representative of a new class of LT receptor antagonists and it has been demonstrated to be several orders of magnitude more potent and selective than most other LT antagonists described to date. The binding of [3H]ICI 198,615 is rapid, specific and saturable. Equilibrium was reached within 5-10 min. Non linear fitting of dissociation time courses has revealed the presence of two different components (K(off)1 = 8.3 +/- 6.8 x 10(-4) sec-1 and K(off)2 = 0.79 +/- 1.66 x 10(-3) sec-1) of the kinetic curves, suggesting heterogeneity of the binding sites. Computer analysis of equilibrium binding data obtained at 25 degrees results in a model with two classes of binding sites, a high affinity-low capacity class with Kd1 = 0.024 +/- 0.014 nM and Bmax1 = 0.015 +/- 0.004 pmol/mg protein and a low affinity-high capacity class with Kd2 = 6326 +/- 3859 nM and Bmax2 = 473 +/- 383 pmol/mg protein. In competition studies, LTD4 was also found to interact with two classes of binding site (Kd1 = 0.016 +/- 0.008 nM and Kd2 = 15195 +/- 8965 nM). On the contrary, LTE4 and LTC4 were found to interact with a homogeneous class of sites only with Kd = 7466 +/- 4629 nM and Kd = 428 +/- 73 nM, respectively. Furthermore, we have evaluated the effect of a number of LT antagonists on the binding of [3H]ICI 198,615. Ro 24-5913 (Kd = 3.0 +/- 2.1 nM), FPL55712 (Kd = 4945 +/- 2868 nM), LY171883 (Kd = 19628 +/- 12365 nM), SKF 104353 (Kd = 74.2 +/- 46 nM) and its enantiomer SKF 104373 (Kd = 13627 +/- 6813 nM) were found to interact with a single class of binding sites. The present studies indicate a heterogeneity of binding sites for ICI 198,615 in membranes from human lung parenchyma and that ICI 198,615 is a very potent and selective antagonist of LTD4 receptors in this tissue.     

Decrease in rat brain calcitonin binding sites and adenylyl-cyclase activity during ageing.

In order to investigate the effects of ageing on the cerebral receptors for calcitonin (CT), we used an in vitro autoradiographic method to study the distribution of the binding sites for eel CT (eCT) in young and old rat brain. The inhibitory action of eCT on adenylyl-cyclase (AC) activity upon isolated brain cell membranes was also evaluated. The results show area-specific reduction of binding particularly in the hypothalamus and pons medulla of the old rat. The inhibitory action of eCT on AC activity was significantly reduced in the same areas, whereas in the striatum and mesencephalon no changes were observed. The parallel decrease of binding of eCT and of the inhibitory action of eCT on AC in ageing may represent a functional decline of neuronal activities during ageing.     

Study on tissue concentrations of antibiotics: bacampicillin in gingiva and maxillary bones

21 patients, whose age ranged from 17 to 60 years and who had not been previously treated with antibiotics or other drugs, received bacampicillin as a perioperative prophylaxis for minor operations in the oral cavity. Four oral doses of bacampicillin were administered: each dose of 800 mg every 12 h, and the last dose was administered 2 h before surgery. To assess bacampicillin serum concentrations two blood samples were collected from each patient: the first sample was obtained 1 h before surgery and the second one during surgery. Together with the second blood sample, small quantities of gingiva and bone were obtained from each patient to also assess the antibiotic concentrations in these tissues (microbiological method). The results show that bacampicillin reaches high concentrations in both the blood and tissues studied by us, and that a direct correspondence exists between blood and gingival and bone tissue concentrations. Furthermore, it should be noted that no postoperative infections developed in our patients. These results lead to the conclusion that bacampicillin appears to be a suitable drug in the therapy of dental infections.     

Dual effects of melatonin on barbiturate-induced narcosis in rats

Melatonin affects the circadian sleep/wake cycle, but it is not clear whether it may influence drug-induced narcosis. Sodium thiopenthal was administered intraperitoneally into male rats pre-treated with melatonin (0.05, 0.5, 5 and 50 mg/kg). Melatonin pre-treatment affected in a dual manner barbiturate narcosis, however, no dose-effect correlation was found. In particular, low doses reduced the latency to and prolonged the duration of barbiturate narcosis. In contrast, the highest dose of melatonin (50 mg/kg) caused a paradoxical increase in the latency and produced a sustained reduction of the duration of narcosis, and a reduction in mortality rate. Melatonin 0.5 and 5 mg/kg influenced the duration but not the latency of ketamine- or diazepam-induced narcosis. Thus, the dual action of melatonin on pharmacological narcosis seems to be specific for the barbiturate mechanism of action.     

Use of the fascial stapler® in proctopexy for rectal prolapse

Proctopexy using synthetic mesh is a popular method of treating rectal prolapse. Suturing the graft to the presacral fascia is time-consuming and can lead to complications. With the fascial staper^®, two parallel rows of three staples are used to quickly and securely anchor the Marlex sling to the sacrum, thus avoiding hemorrhage from the presacral veins. Fourteen patients have been treated with no complications.     

Early Transplant Arteriopathy in Kidney Transplantation

BackgroundEarly dysfunction of renal allografts may be associated with vascular injury, which raises the specter of active rejection processes that require medical intervention. In our practice, we have encountered patients who present with delayed graft function and demonstrate a unique pattern of endothelial cell injury that raises concern for rejection in their biopsy. Therefore, we sought to systematically determine the biopsy characteristics and outcome of these patients.MethodsDuring a 17-year period at the University of Washington in Seattle, United States, we identified 24 cases of a distinct arterial vasculopathy presenting in the first year posttransplantation. This early transplant arteriopathy (ETA) is characterized by endothelial cell swelling and intimal edema but without the intimal arteritis that defines vascular rejection.ResultsApproximately 1% of transplant biopsies during the study period showed ETA, almost all of which were in deceased donor organs (96%), and most presented with delayed graft function (54%) or increased serum creatinine (38%) soon after transplantation (median 13 days; range, 5-139). In this study, 77% of patients were managed expectantly, with only 2 patients (7.6%) subsequently developing acute vascular rejection. Except for 1 patient who died, all patients had functioning allografts at 1 year follow-up.ConclusionRecognizing ETA and distinguishing it from vascular rejection is important to prevent over-treatment because most patients appear to recover allograft function rapidly with expectant management.     

Characterization of the Ca2+ responses evoked by ATP and other nucleotides in mammalian brain astrocytes

1. This study was aimed at characterizing ATP-induced rises in cytosolic free calcium ion, [Ca²⁺]_i, in a population of rat striatal astrocytes loaded with the fluorescent Ca²⁺ probe Fura2, by means of fluorescence spectrometry.
2. ATP triggered a fast and transient elevation of [Ca²⁺]_i in a concentration-dependent manner. The responses of the purine analogues 2-methylthio-ATP (2-meSATP), adenosine-5′-O-(2-thiodiphosphate) (ADPβS), as well as uridine-5′-triphosphate (UTP) resembled that of ATP, while α,β-methylene-ATP (α,β-meATP) and β,γ-methylene-ATP (β,γ-meATP) were totally ineffective.
3. Suramin (50 μM) had only a minor effect on the ATP response, whereas pyridoxal phosphate-6-azophenyl-2′,4′-disulphonic acid (PPADS) (5 μM) significantly depressed the maximum response.
4. Extracellular Ca²⁺ did not contribute to the observed [Ca²⁺]_i rise: removing calcium from the extracellular medium (with 1 mM EGTA) or blocking its influx by means of either Ni²⁺ (1 mM) or Mn²⁺ (1 mM) did not modify the nucleotide responses.
5. Furthermore, after preincubation with 10 μM thapsigargin, the nucleotide-evoked [Ca²⁺]_i increments were completely abolished. In contrast, 10 mM caffeine did not affect the responses, suggesting that thapsigargin-, but not caffeine/ryanodine-sensitive stores are involved.
6. Both application of the G-protein blocker guanosine-5′-O-(2-thiodiphosphate) (GDPβS) (1 mM) and preincubation with pertussis toxin (PTx) (350 ng ml⁻¹) partially inhibited the nucleotide-mediated responses. Moreover, the phospholipase C (PLC) inhibitor U-73122, but not its inactive stereoisomer U-73343 (5 μM), significantly reduced the ATP-evoked [Ca²⁺]_i rise.
7. In conclusion, our results suggest that, in rat striatal astrocytes, ATP-elicited elevation of [Ca²⁺]_i is due solely to release from intracellular stores and is mediated by a G-protein-linked P2Y receptor, partially sensitive to PTx and coupled to PLC.

     

Predictability of PSA failure in prostate cancer by computerized cytometric assessment of tumoral cell proliferation

OBJECTIVES: To evaluate the relationship of DNA ploidy and cell proliferation (CP) with Gleason score (GS) and clinical outcome in prostate cancer. METHODS: Sixteen patients with benign prostatic hyperplasia (BPH) and 65 patients with prostate cancer classified by GS (four groups: 2 to 4, 5 to 6, 7, and 8 to 10) were studied. All patients with carcinoma underwent prostatectomy and were separated into prostate-specific antigen (PSA) failure and nonfailure groups (failure if PSA 0.1 ng/mL or more three times after surgery). Tumoral CP (Ki-67 inmunostaining and SG2M phase) and DNA ploidy were evaluated by computerized cytometry. RESULTS: BPH were diploid with low CP (8% SG2M cells or less). Carcinomas were either diploid with high CP (greater than 8% SG2M cells) or aneuploid. CP was significantly higher (P <0.001) in tumors with GS 7 or greater than in tumors with GS less than 7 (mean percent Ki-67 cells 18.3% versus 7.8%, respectively). PSA failure increased with GS (7.1% in GS 2 to 4, 21% in GS 5 to 6, 28.6% in GS 7, and 50% in GS 8 to 10), as well as with aneuploidy (18.5% in diploid tumors versus 72.7% in aneuploid tumors). Those experiencing PSA failure had significantly higher (P <0.001) CP than those not failing (mean percent Ki-67 cells 24% and mean percent SG2M 30.4% versus 8.7% and 13.5%, respectively). Cox regression analysis showed GS, DNA ploidy, Ki-67, and SG2M to each be univariately prognostic for time to PSA failure; however, Ki-67 and SG2M were more highly significant (P <0.0001 for both) than GS (P = 0.007) or DNA ploidy (P = 0.002). After adjusting for either SG2M or Ki-67 measures of CP, neither ploidy nor GS contained additional prognostic value. CONCLUSIONS: Tumor CP and DNA ploidy can be reliably determined in prostate cancer by computerized cytometry. On the basis of our preliminary results, CP correlates well with GS and predicts PSA failure better than DNA ploidy or GS.     

Type I insulin-like growth factor receptor function in breast cancer

Experimental evidence suggests an important role of the type I IGF receptor (IGF-IR) in breast cancer development. Breast tumors and breast cancer cell lines express the IGF-IR. IGF-IR levels are higher in cancer cells than in normal breast tissue or in benign mammary tumors. The ligands of the IGF-IR are potent mitogens promoting monolayer and anchorage-independent growth of breast cancer cells. Interference with IGF-IR activation, expression, or signaling inhibits growth and induces apoptosis in breast cancer cells. In addition, recent studies established the involvement of the IGF-IR in the regulation of breast cancer cell motility and adhesion. We have demonstrated that in MCF-7 cells, overexpression of the IGF-IR promotes E-cadherin-dependent cell aggregation, which is associated with enhanced cell proliferation and prolonged survival in three-dimensional culture.The expression or function of the IGF-IR in breast cancer cells is modulated by different humoral factors, such as estrogen, progesterone, IGF-II, and interleukin-1. The IGF-IR and the estrogen receptor (ER) are usually co-expressed and the two signaling systems are engaged in a complex functional cross-talk controlling cell proliferation.Despite the convincing experimental evidence, the role of the IGF-IR in breast cancer etiology, especially in metastatic progression, is still not clear. The view emerging from cellular and animal studies is that abnormally high levels of IGF-IRs may contribute to the increase of tumor mass and/or aid tumor recurrence, by promoting proliferation, cell survival, and cell-cell interactions. However, in breast cancer, except for the well established correlation with ER status, the associations of the IGF-IR with other prognostic parameters are still insufficiently documented.