VITAMIN A AT PHARMACOLOGIC DOSES AMELIORATES THE MEMBRANE LIPID PEROXIDATION INJURY AND TESTICULAR ATROPHY THAT OCCURS WITH CHRONIC ALCOHOL FEEDING IN RATS

The interaction of ethanol (ETOH) with testicular subcellularmembranes contributes, at least in part, to alcohol-inducedgonadal dysfunction. Vitamin A reaches the testes via the circulationas the retinyl ester and is converted to the free alcohol (retinol)and then to the aldehyde (retinal); retinal is the form of thevitamin which is essential for normal spermato-genesis. Becauseretinol can function as a free radical scavenger, testicularmitochondria were evaluated for evidence of a protective roleprovided by supplemental dietary vitamin A on ETOH-induced alterationsin testicular structure and function in rats. Lipid peroxidationwas evaluated by measurement of malonaldehyde formation andglutathione content of the testes. Compared to isocaloricallymatched dextrimaltose-fed controls (ISO) receiving a modifiedvitamin A containing diet, rats fed the corresponding ETOH dietfor 50 days had a reduced testes/body ratio (ETOH: 0.0114±0.0004vs ISO: 0.0128 ±0.0004). Mitochondrial enriched extractsobtained from the testes of these ETOH-fed rats showed significantincreases in malonaldehyde formation; moreover, gluthathionelevels were reduced in the testes of the alcohol-fed animalswhen compared to their isocaloric controls. In contrast, noevidence for testicular atrophy was present in ETOH-fed ratsreceiving a standard vitamin A enriched diet; moreover, suchETOH-fed rats had a reduced rate of malonaldehyde formationas compared to their respective controls. Similarly, glutathionelevels were not depleted in the testes of the ETOH-fed ratsreceiving the vitamin A enriched diet. Taken together, thesedata suggest that lipid peroxidation is a consequence of ethanolmetabolism which can be attenuated, at least in part, by vitaminA.     

Mannan-Binding Protein and Bovine Conglutinin Mediate Enhancement of Herpes Simplex Virus Type 2 Infection in Mice

A broad range of plant lectins have recently been shown to inhibit the infectivity of herpes simplex virus type I (HSV-1) in viiro . We decided to investigate the role of mammalian Icctins in infection witb herpes simplex virus. Two lectins, conglutinin and mannan-binding protein (also called mannose-binding protein. MBP). belonging to the collectin family of lectins, were examined.
Four week-old BALB/c mice were injected subcutaneously with 100 μg bovine conglutinin or 50 μg human MBP 1 day before intravenous infection with 5 × 10⁴ PFU of herpes simplex virus type 2 (HSV-2). A three-fold increase in virus titre of the liver was observed on day 3 of the infection in the mice pretreated with conglutinin or MBP. whereas no effect was seen on days I and 5.
In a standard plaque assay using Vero cells we were not able to demonstrate reproducibly either infection inhibition or infection enhancement, when virus was pre-incubated with differing concentrations ofthe collectins. Tbe concentrations used were similar to tbose used by us in livo , and by others in in vitro experiments showing inhibition of the infectivity of HSV-1 with plant lectins.
In an ELISA with HSV-2 antigens captured on anti-HSV-2 antibodies, calcium-dependent and carbohydrate inhibitabte binding of the collectins was observed. Our results indicate that the effect of endogenous mammalian collectins in vivo may not be neutralization as suggested by the data using plant lectins. Instead, the previously described opsonizing activity of the mammalian collectins may provide the virions witb an alternative port of entry into cells leading to infection enhancement.     

A Low Serum Concentration of Mannan-Binding Protein is Not Associated with Serogroup B or C Meningococcal Disease

The mammalian C-type serum lectin, mannan-binding protein (MBP), may induce Clq- and antibody-independent activation of the classical pathway of complement. Accordingly, MBP is considered as a member of the complement system. Complement deficiencies have been found with increased frequency in patients with meningococcal disease. Therefore, we investigated the MBP levels in patients with meningococcal disease. Ninety-nine Norwegian individuals (age 12–21 years) who survived severe systemic disease caused by serogroup B or C meningococci were investigated. No significant differences were observed in the MBP concentration between patients with serogroup B (n = 76) or C (n = 25) disease and healthy blood donor controls (n = 40) (P >0.05). The frequency of patients with low levels of MBP (< 100 μg/1) was 10.1%. This was not different from controls (12.5%). Thus, low MBP concentrations do not appear to predispose to serogroup B or C meningococcal disease.