Biochemical analysis of human milk treated with sodium dodecyl sulfate, an alkyl sulfate microbicide that inactivates human immunodeficiency virus type 1.

Reduction of transmission of human immunodeficiency virus type 1 (HIV-1) through human milk is needed. Alkyl sulfates such as sodium dodecyl sulfate (SDS) are microbicidal against HIV-1 at low concentrations, have little to no toxicity, and are inexpensive. The authors have reported that treatment of HIV-1-infected human milk with < or = 1% (10 mg/mL) SDS for 10 minutes inactivates cell-free and cell-associated virus. The SDS can be removed with a commercially available resin after treatment without recovery of viral infectivity. In this article, the authors report results of selective biochemical analyses (ie, protein, immunoglobulins, lipids, cells, and electrolytes) of human milk subjected to SDS treatment and removal. The SDS treatment or removal had no significant effects on the milk components studied. Therefore, the use of alkyl sulfate microbicides to treat milk from HIV-1-positive women may be a simple, practical, and nutritionally sound way to prevent or reduce transmission of HIV-1 while still feeding with mother's own milk.     

Ganglioside composition of human neuroblastomas. Correlation with prognosis. A Pediatric Oncology Group Study

The ganglioside composition of neuroblastoma samples from 53 patients was determined. Tumor sites included the adrenals (15), and the thoracic (20), abdominal (15), and pelvic (3) areas. Age of the patients at the time of surgery ranged from 1 day to over 10 years and the Stage of the tumors from A to D. Differences in ganglioside patterns were observed, with neuroblastomas from patients who were either disease positive or dead of disease tending to have more monosialogangliosides and fewer gangliotetraose gangliosides of the B series (formula; see text) than tumors from patients who were disease-free. More specifically, six of the seven patients lacking GT1b died of disease, suggesting that the absence of GT1b is indicative of a poor prognosis.     

Adherence of botulinum and tetanus neurotoxins to synaptosomal proteins

The ability of 125I-labeled botulinum type A and tetanus neurotoxins to adhere to blots of synaptosomal proteins separated by SDS-polyacrylamide gel electrophoresis was studied. Both neurotoxins appeared to adhere preferentially to an approximately 80 kDa and to a lesser extent to an approximately 116 kDa protein(s). Adherence of the neurotoxins to these proteins was enhanced by preincubation of the neurotoxins with GT 1b. The approximately 100 kDa heavy chain segment of BTxA adhered to the same proteins. The carboxy terminal half of the heavy chain adhered primarily to the approximately 80 kDa protein(s) while the amino terminal portion bound most intensely to the approximately 116 kDa protein(s). The ability of the approximately 80 and approximately 116 kDa proteins to stain positively with the periodic acid-Schiff reagent and to bind 125I-labeled wheat germ lectin suggests that they are glycosylated. Both neurotoxins appear to adhere to the same approximately 80 and approximately 116 kDa proteins because tetanus neurotoxin preincubated with GT 1b was able to reduce binding of radiolabeled botulinum type A neurotoxin to both proteins. Neither neurotoxin adhered to blots of proteins from liver, spleen, or kidney, suggesting that the proteins adhered to are neural components.     

Differential accumulation of gangliosides by the brains of MPTP-lesioned mice

Although gangliosides have been reported to enhance recovery from 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced lesions of the substantia nigra, evidence as to whether the administered gangliosides actually reach this or any other site of lesion in the central nervous system (CNS) at which they putatively enhance recovery is lacking. Therefore, studies were carried out to determine the amount of ³H-labeled ganglioside that was accumulated by the brains of MPTP-treated mice as well as by brains of control mice. No significant difference in the accumulation of ³/-bovine brain gangliosides or ³H-GD1a was seen between lesioned and control brains up to 240 min after injection of the labeled lipids. However, significantly more label was associated with the brains of MPTP-treated mice compared to controls 120 and 240 min after the injection of ³H-GM1. Analysis of the lipids extracted from the brain of a ³H-GM1-treated mouse revealed that the majority of label was still associated with ³-GM1, 240 min after its administration. Autoradiography of tissue sections from the brains of MPTP-treated mice injected with ³H-GM1 showed that label was present in the ventricular spaces of the brain. This observation suggests that the administered gangliosides are present in the cerebrospinal fluid, which indicates that they have the potential to reach the lesioned CNS site at which they putatively enhance recovery. © 1994 Wiley-Liss, Inc.     

Effects of exogenous GM1 and GD1a on S20Y neuroblastoma cells

The effects of exogenous GM1 and GD1a on S20Y murine neuroblastoma cells were assessed by monitoring morphology, tumorigenicity, mitotic index, and plating efficiency. S20Y cells were seeded at a density equivalent to 5 X 10(4) cells per 35-mm tissue culture dish; 38-42 hr after seeding (preconfluent stage) the cells were treated for 12 hr with 100 micrograms of ganglioside per ml of medium in which the serum content was reduced from 10% to 0.5%. Analysis of the cell lipids indicated that added ganglioside became tightly associated with the membrane during the 12-hr exposure. GM1 treatment resulted in increased projections on the cell surface and fine structures projecting from the cell processes. GD1a treatment resulted in a reduction in the cellular mitotic index. Plating efficiency was reduced by both GM1 and GD1a. Neither ganglioside affected tumorigenicity of the S20Y cells. Twelve hours after removal of the added ganglioside and exposure of the cells to normal medium, the ganglioside composition of the membranes from treated cells approached that of the controls, and the ganglioside-induced effects had been reversed. These results suggest that addition of specific gangliosides induces different cellular responses and that these changes are dependent upon the continued presence of the ganglioside.     

Multivalent dendrimeric compounds containing carbohydrates expressed on immune cells inhibit infection by primary isolates of HIV-1

All herpesviruses encode a homolog of the herpes simplex virus type-1 UL11 tegument protein. Deletion of UL11 disrupts virus envelopment, causes capsid accumulation within the cytoplasm, and reduces virus release. UL11 requires acylation with myristate and palmitate for membrane binding, lipid raft trafficking, and accumulation at the site of virus envelopment. Thus, it was predicted that acylation of UL11 would be necessary for efficient virion production, similar to HIV-1 Gag which requires myristylation for virus production. Accordingly, recombinant viruses were created to express UL11 derivatives that are not acylated, are partially acylated, or contain foreign acylation signals. Unexpectedly, the non-acylated UL11 rescued some growth defects of a UL11-null mutant, even though the unmodified protein was unstable. Furthermore, a myristylated and palmitylated chimera did not fully rescue the null virus. These results suggest that UL11 maintains some function(s) when not membrane-bound, and the sequence context of the acylations is important for UL11 function.     

Glycoconjugates: roles in neural diseases caused by exogenous pathogens

Numerous reports indicate that lipid or protein associated carbohydrates are essential for infection of cells by various viruses, bacteria, or bacterial toxins, some of which affect the nervous system. Examples of such pathogens include tetanus and botulinum neurotoxin, Shiga and Shiga-like toxins, Borrelia burgdorferi, Mycobacterium leprae, and human immunodeficiency virus. This review discusses evidence indicating that carbohydrates are essential for these pathogens to induce their deleterious effects, the putative function of the carbohydrates, and how this knowledge might be used to combat the effects of the pathogen.     

Cellular effects of a brain extract factor or factors inhibiting neuroblastoma cell growth in vitro

The mechanism of inhibition of neuroblastoma cell proliferation in vitro by extract prepared from the brains of newborn mice was partially elucidated. Flow cytometric analysis of propidium iodide-stained cells showed that a significant increase occurred in the pre-G0/G1 cell population after exposure to the extract for 24 hr. Fluorescence microscopy indicated that the pre-G0/G1 cells had small "micronuclei" in association with their nucleus, whereas post-G2/M cells had enlarged propidium iodide-staining nuclei. 3H-thymidine incorporation was unchanged from that of control cells, in cells exposed to the extract for either 6 or 24 hr. No effect was seen on choline acetyl transferase activity or on morphology. These results suggest that the inhibitor blocks neuroblastoma cell proliferation either by inducing an uneven distribution of DNA at the time of cell division or by altering its packaging within the nucleus.     

Dendrimers and antivirals: a review

In response to the need for antiviral agents, dendrimers, hyper-branched, well-defined, and chemically versatile molecules, have been found to have a number of potential uses. How they are used is based on knowledge of 1) how a virus interacts with its target cells, 2) how it replicates, and 3) which viral components are recognized by the immune response of the host. Many viral-host cell interactions are initiated by viral proteins binding to specific cell surface carbohydrates. Dendrimers offer an efficient means of presenting multiple ligands, or sites of contact, on a single molecule. Derivatized with carbohydrate residues, the multivalent ligands have been shown to inhibit viral binding. Dendrimers derivatized with peptides or anionic groups have also been found to inhibit infection. The availability of a number of different types of dendrimers permits synthesis of potential inhibitors of viral binding to be tailored to meet the dimensions needed for optimum adherence by the virus. Future directions should see increased studies of the use of dendrimers as carriers of 1) multiple indicators on a viral probe to increase diagnostic sensitivity, 2) multiple peptides for use as immunogens or as inhibitors of viral binding, and 3) inhibitors of viral enzymes. While the field of dendrimer chemistry is relatively young, promising results indicate that dendrimers may provide the scaffolding needed for development of effective antivirals.     

Sialidase activity of oncogenic cells transformed by herpes simplex virus

Sialidase in normal nononcogenic hamster embryo fibroblasts was not active toward added disialo- and trisialoganglioside, but all transformed lines of hamster embryo fibroblasts studied had sialidase active toward added ganglioside substrate. The levels of exogenous sialidase activity suggested a parallel trend in the amount of this activity and the degree of oncogenicity of the transformed cells. Exogenous sialidase activity in a weakly oncogenic cell line was found to increase after passage of the cells into hamsters and isolation and cell culture of the resulting tumors which gave rise to a cell line of relatively high oncogenicity.