Endothelial cytoskeletal elements are critical for flow-mediated dilation in human coronary arterioles

Mitochondrial H₂O₂ contributes to flow-mediated dilation (FMD) in human coronary arterioles (HCA). We examined the hypothesis that the endothelial cytoskeleton plays a critical role in transducing endothelial wall shear stress into a stimulus for releasing mitochondrial ROS. Phallacidin together with α-, β-tubulin antibodies and Mito-Tracker Red showed the proximity of F-actin, microtubules and mitochondria in endothelial cells. Cytochalasin D (CytoD) and nocodazole (Noc) disrupted endothelial F-actin and microtubules in HCA, respectively, concurrent with a reduction in the generation of cytosolic O₂ ^•− and H₂O₂ (hydroethidine and dichlorodihydrofluorescein fluorescence) and mitochondrial superoxide (mitoSox) during flow (control: 3.5 ± 1.6, Cyto D: 0.51 ± 0.2, Noc: 0.81 ± 0.6). FMD, but not the dilation to bradykinin or papaverine, was reduced by Cyto D (26 ± 10% vs. 56 ± 3%) or Noc (26 ± 11% vs. 58 ± 7%). These results suggest that cytoskeletal elements are a critical component of the signaling mechanism linking endothelial shear stress and mitochondrial release of ROS in the human coronary microcirculation.     

Inhibition of Feline Immunodeficiency Virus Infectionin Vitroby Envelope Glycoprotein Synthetic Peptides

Sixty-six 20- to 23-amino-acid synthetic peptides, partially overlapping by 10–12 amino acids, spanning the entire sequence of the envelope SU and TM glycoproteins of the Petaluma isolate of FIV, have been used to investigate the Env domains involved in viral infection. Peptides 5 to 7, spanning amino acids²²⁵E–P²⁶⁴located in a conserved region of the SU protein, and peptides 58 to 61, spanning amino acids⁷⁵⁷N–P⁸⁰⁶and encompassing hypervariable region 8 of TM protein, exhibited a remarkable and specific antiviral effect against the homologous and one heterologous isolate, as judged by inhibition of FIV-induced syncytium formation and p25 production in CrFK cells. Peptides 5 and 7, but not peptides 58 and 59, also inhibited viral replication of a fresh FIV isolate on nontransformed lymphoid cells. By flow cytometry, peptides 5, 7, 58, and 59 were shown to bind the surface of FIV permissive cells. The antiviral activity of peptides 5 and 7, however, was time-dependent, as inhibition of FIV replication was seen when the peptides were administered before or within 3 hr after virus inoculation; in contrast, TM peptides 58 and 59 exerted a potent inhibitory effect when added up to 24 hr after virus inoculation. Circular dychroism analysis showed that peptide 5 folds to a helical conformation in the presence of a hydrophobic environment. Although the basis for the antiviral action of the peptides is not understood, our data suggest that the inhibitory peptides may act by interacting with cell-surface molecules involved in viral infection.     

Plasminogen receptors, urokinase receptors, and their modulation on human endothelial cells

Endothelial cells are centrally involved in regulation of fibrinolysis, and receptors for plasminogen and urokinase provide a mechanism by which cells can regulate their fibrinolytic function. Therefore, the existence and characteristics of receptors for these fibrinolytic components on cultured human umbilical vein endothelial cells were examined. We verified the presence of plasminogen receptors on these cells (Kd = 2.1 +/- 1.3 mumol/L, and 1.8 +/- 1.3 x 10(7) binding sites/cell). These binding parameters and other characteristics indicate that these receptors are closely related to the plasminogen receptors on many circulating and adherent cells. Specific binding sites that interact with two-chain urokinase of mol wt 55,000 with a dissociation constant of 2.1 +/- 1.7 nmol/L, with 2.9 +/- 2.9 x 10(5) sites/cell were also identified. Single-chain urokinase of mol wt 55,000, but not the two-chain degradation product of mol wt 33,000 bound to the cells, implicating the amino-terminal aspects of the ligand in receptor recognition. When endothelial cells were stimulated with thrombin, an agent that modulates their fibrinolytic potential, both receptor types were modestly affected; urokinase binding increased 17%, whereas plasminogen binding decreased 19%. The presence and modulation of plasminogen and urokinase receptors provide a potentially important additional mechanism by which endothelial cells may regulate fibrinolysis.     

Experimental infections of the musculoskeletal system: evaluation with MR imaging and Tc-99m MDP and Ga-67 scintigraphy

Acute osteomyelitis, soft-tissue infection, or both were experimentally produced in 38 New Zealand white rabbits, and three-phase technetium-99m methylene diphosphonate, gallium-67, and magnetic resonance (MR) images were obtained 7 or 14 days after infection. There was no significant difference between radionuclide studies and MR images in the detection of osteomyelitis, but MR imaging was significantly more sensitive (100% vs. 69%; P less than .01) in the detection of soft-tissue infection. In addition, cellulitis could not be distinguished from soft-tissue abscess on radionuclide studies, whereas MR imaging was 92% accurate in depicting soft-tissue abscesses. Further research is necessary to determine how to relate these findings to true human clinical situations.     

Chronic Toxicity and Carcinogenicity Studies with the {beta}-Adrenoceptor Antagonist Levobunolol

The chronic toxicity and carcinogenicity of levobunolol, a nonselectiveß-adrenoceptor antagonist, was evaluated in Swissmice and Wistar rats. The drug was administered in the dietto mice at 0, 12, 50, and 200 mg/kg/day for 80 weeks and torats at 0, 0.5, 2, 5, 30, and 180 mg/kg/day for 2 years. Inmice, uterine leiomyomas were present in 4 of 50 females at200 mg/kg but not in any other group. The incidences of othertumor types, as well as pathologic findings, were comparableamong groups. In rats, significant body weight gain suppressionoccurred at 5, 30, and 180 mg/kg. Brown discoloration of perianalfur and steel-gray discoloration of hairless skin were evidentin high-dose rats. A generalized steel-gray discoloration ofinternal organs and tissues occurred in the 30 and 180 mg/kggroups. No other differences between treated and control groupswere evident. The clinical relevance of the increased incidenceof uterine leiomyoma in mice is questionable because it occurredonly in one species at more than 200 times the projected therapeuticdose.     

Effect of isoproterenol on serum potassium and magnesium

Some ventricular arrhythmias can be related to a decrease inthe level of potassium (K) and/or magnesium (Mg). Because adrenergicstimulation decreases serum K⁺ and Mg⁺⁺, we decided to investigatethe effects of a beta-receptor agonist, isoproterenol, on serumK⁺ and Mg⁺⁺, and their consequences on the induction of tachycardia.Programmed atrial and ventricular stimulation was performedin 95 patients before and during infusion of 1.6µg . ml^–1of isoproterenol. During isoproterenol infusion, 61 patientshad no inducible tachycardias (group I) and 34 had induciblesustained tachycardias (group II): 16 of them (group IIA) hadinducible sustained supraventricular tachyarrhythmias and 18(group IIB) had inducible sustained ventricular tachycardia.Serum K⁺ and Mg⁺⁺ were measured at the end of stimulation inthe control state and during isoproterenol infusion. The basalvalues in groups I and II did not differ (3.8 + 0.38 vs 3.86+ 0.39 mEq . 1^–1 for K⁺, and 20.18 + 2.68 vs 19.83+1.63mg l^–1 for Mg⁺⁺). Isoproterenol infusion induced a significant(P<0.001) hypokalaemia in all groups and a decrease in serumMg in group II: there was a significant decrease in serum Mg⁺⁺(P<0.05) in group IIA (19.55±1.7 vs 20.4 + 4.6). Thedecrease in serum Mg⁺⁺ in group IIB (18.9+1.55 vs 19.32 + 1.63)was not significant. However the serum Mg⁺⁺ level during isoproterenolinfusion was significantly lower in group IIB than in groupI. In conclusion, the infusion of isoproterenol was responsiblefor a significant hypokalaemia, which did not explain the inductionof tachycardia. On the other hand, it also induced a decreasein serum Mg⁺⁺, which might facilitate the induction of supraventricularand ventricular tachycardia.     

Maternal and paternal moderate daily alcohol consumption and unexplained miscarriages

Summary. The relation between parental moderate alcohol consumption and the risk of miscarriage was analysed using data from a casecontrol study in Milan between January 1987 and June 1988. Cases were 94 women who had two or more 'unexplained' miscarriages (after exclusion of genetic, endocrine and Miillerian factors) and without full-term pregnancies, admitted or referred to the First Obstetric and Gynecologic Clinic of the University of Milan. A total of 176 women admitted for normal delivery on selected days to the same university clinic and without previous miscarriages were chosen as controls. Compared with non-drinkers the risk of recurrent miscarriage was 0·9 for regular drinkers. The point estimates were 0·9 for women reporting one drink per day and 0·8 for those reporting two or more. Compared with non-drinkers, the relative risk estimates for drinking by fathers were slightly above unity, being 1·7 for less than three drinks and 1·4 for three or more drinks per day, but the trend in risk was not statistically significant.     

Human leukocyte interferon-mediated granulopoietic differentiation arrest and its abrogation by lithium carbonate

Interferon has been shown to inhibit erythropoietic and granulopoietic differentiation. Since lithium carbonate (Li) elevates granulocyte levels in a variety of neutropenic disorders, we investigated the effect of Li on human leukocyte interferon (HLIF)-mediated inhibition of granulopoietic differentiation. Using an agar culture technique for cloning granulocyte-macrophage progenitor cells (GM-CFC), we demonstrated that Li blocks HLIF-induced granulopoietic differentiation arrest in a dose-dependent manner. Results of removal of T lymphocytes from marrow cells suggest that this Li effect is not mediated through marrow T lymphocytes.