HTLV-I activates complement leading to increased binding to complement receptor-positive cells

This investigation was performed to determine whether HTLV-I can activate complement, since previous studies show that complement activation by some viruses, including HIV-1, can enhance binding to, and infection of complement receptor-positive (CR+) cells. Complement treatment increased binding of HTLV-I to CR+ HPB-ALL cells by approximately 5-fold. In contrast, increased binding was not observed with H9 cells, which lack CR. Heat inactivation or EDTA treatment of complement blocked this increased binding while EGTA treatment only partially blocked binding. Anti-CR2 antibody significantly blocked binding of complement-treated HTLV-I to HPB-ALL cells. Since previous studies showed that HIV-1 could activate complement, activation of complement by this virus was compared with HTLV-I. It was observed that binding of HTLV-I to HPB-ALL cells was enhanced by highly dilute complement (> or = 1:810) while HIV-1 required much higher concentrations of complement (> or = 1:30), indicating that HTLV-I is a much stronger complement activator. Treatment with complement transiently increased the ability of HTLV-I to infect CR+ cell lines as judged by provirus formation (4- to 8-fold increase) and p24 production (5- to 10-fold increase). In contrast, complement treatment did not increase infection of CR- cells. In conclusion this study shows that HTLV-I activates complement leading to increased binding to, and transiently increased infection of, CR+ cells. This complement-mediated increased binding of HTLV-I may dramatically affect viral trafficking and immunological reactivity of virus in vivo.     

Neomycin inhibits secretion of apolipoprotein[a] by increasing retention on the hepatocyte cell surface

Neomycin therapy reduces plasma levels of low density lipoprotein and lipoprotein[a] (Lp[a]). To determine whether neomycin directly alters the biogenesis of Lp[a], we have examined the effect of neomycin on apolipoprotein[a] (apo[a]) synthesis and secretion in primary cultures of baboon hepatocytes. Using this system, we have previously shown that apo[a] is synthesized as a lower molecular weight precursor that upon maturation becomes associated with the cell surface before release into the culture medium. Treatment of hepatocytes with 10 mM neomycin reduced levels of apo[a] in the culture medium by as much as 12-fold. Although a portion of the reduced secretion could be accounted for by a reduction in total protein synthesis, the greatest effect of neomycin on apo[a] secretion was to decrease the release of mature apo[a] from the hepatocyte cell surface into the culture medium. Treatment of hepatocyte cultures with trypsin confirmed that mature apo[a] in neomycin-treated cells was still transported to the cell surface. Examination of related antibiotics demonstrated that inhibition of apo[a] secretion is a general property shared by the deoxystreptamine antibiotics. The mechanism by which neomycin affects the apo[a]-cell surface interaction is not known, but neomycin is known to perturb cell surface membranes, inhibit the interaction of some ligands with their cell surface receptors, and inhibit the metabolism of phosphatidylinositol 4,5 biphosphate. These studies suggest that cell surface association of apo[a] may play a role in Lp[a] biogenesis in vivo.     

Microsurgery and changes in the testicular and epididymal production of spermatozoa

The researchers studied a group of azoospermic patients with obstructions of the seminal canals and a group of oligoasthenospermic patients suffering from varicocele in order to analyze the factors that influence the success of surgery aimed at recovering fertility. In the 46 patients suffering from obstructions of the deferent duct and the extremity of the epididymis, the time factor proved decisive if the obstruction lasted longer than 6 years: in this case, damage to the seminiferous tubules is not reversible. With obstructions dating back less than 4 years, the causes and the location of the obstruction are more incisive. Success was achieved in 100% of vasectomy cases and in 37.5% of epididymal-deferential anastomoses. In research literature, the superiority of microsurgery for treating these types of pathologies is taken for granted. In patients affected by oligoasthenospermia the effectiveness of laparoscopic ligation of the spermatic veins was compared to that of the Belgrano I technique. Of the 30 patients with bilateral varicocele and oligoasthenospermia dating back less than 4 years, 73.3% of the 15 patients operated on using the Belgrano 1 technique experienced sperm normalization; in the 15 cases operated on using laparoscopic ligation of the spermatic canals, normalization was much less frequent. Seventy-five percent of another group of 40 patients whose infertility did not have a duration of longer than 4 years and were operated on using microsurgery techniques were normalized. The percentage of the 60 oligoasthenospermic patients for longer than 6 years normalized was 16.6%.     

Detecting biomolecules in picoliter vials using aequorin bioluminescence

The quantitative determination of proteins in picoliter-volume vials is described. The assay is based on the bioluminescence of the photoprotein aequorin along with photon-counting detection. Using this approach, avidin can be detected at femtomole levels by taking advantage of its inhibitory effect on the bioluminescence signal generated by biotinylated recombinant aequorin. The picoliter vials were fabricated on glass substrates using a laser ablation technique. Parameters that affect the reproducibility of the assay such as the fabrication and calibration of the pipets, the fabrication of the vials, and the composition of the assay solutions were studied.     

Hepatocellular carcinoma in mixed cryoglobulinemia patients

Rosacea is an uncommon disease of the eye and facial skin. Ocular rosacea is often undiagnosed by the ophthalmologist especially when skin manifestations are not evident yet. Early diagnosis and treatment is important to decrease morbidity of this potentially blinding disease. A case of ocular rosacea in a 14-year-old Chinese girl is reported. Our patient presented with chronic non-specific keratoconjunctivitis. Only much later did the characteristic corneal and facial skin lesions appear. She responded to guttae prednisolone, oral and guttae tetracycline. This case illustrates the difficulty of early diagnosis when ocular manifestations precede those of the skin. We believe this is the first case of ocular rosacea reported in Singapore.     

N6,C8-distributed adenosine derivatives as partial agonists for adenosine A1 receptors

The synthesis and biological evaluation of N6, C8-disubstituted derivatives of adenosine as potential partial agonists for adenosine receptors is described. Via three routes, two series of compounds were prepared, viz., N6-cyclopentyladenosine derivatives 3a-e and C8-(cyclopentylamino)adenosine analogs 3e and 9a-d, respectively. The X-ray structure determination of one of these compounds, N6-ethyl-8(cyclopentylamino)adenosine (9b), was carried out (orthorhombic, space group P2(1)2(1)2(1) (No. 19) with a = 11.039(3), b = 8.708(2), and c = 24.815(12) angstrom, Z=4,R1=0.0974,R2(W) = 0.2455). Due to intramolecular hydrogen bonding, the ribose moiety of this compound is in an anti conformation. The compounds were tested in vitro in radioligand binding studies, yielding their affinities for A1 and A2a adenosine receptors. All compounds appeared A1 selective, with affinities in the high nanomolar, low micromolar range. On A1 receptors the so-called GTP shift was also determined, i.e., the ratio between the affinities measured in the presence and absence of 1 mM GTP. All GTP shifts (values between 1.1 and 3.8) were lower than the GTP shift for CPA (6.0). This GTP shift appeared indicative for partial agonism in vivo, since the N6-cyclopentyladenosine derivatives showed lower intrinsic activities than the prototypic full agonist N6-cyclopentyladenosine on the decrease in heart rate in conscious, normotensive rats.