Comparitive study of the milk fat globule membrane and the mouse mammary tumour virus prepared from the milk of an infected strain of Swiss albino mice

Milk fat globule membranes and mammary tumour virus particles (d = 1.17 g/cm³) have been obtained from the milk of a Swiss albino mice strain. Comparitive biochemistry shows that these two structures differ significantly in the phospholipid, polypeptide and glycopolypeptide patterns and enzymatic activities. However, the lipid profile and the morphology of both structures suggest a filiation with the plasma membrane. Density fractions obtained from the crude virus preparation have been thoroughly investigated. The results suggest that most of these fractions represent degraded virus and/or atypical virus assembly.     

Design and evaluation of head unit for wheelchair control by quadriplegic patients.

A control unit was designed to allow persons who have lost hand and arm function to control the speed, steering, reversal and on-off switching of an electric wheelchair by means of backward movement and rotation of the head. When possible, shoulder movement was used to control both reversal and on-off switching. Clinical evaluation in 10 patients with quadriplegia and 2 with severe neuromuscular disease showed that the unit neither interfered with nor restrained the patients'' residual body movements, permitted use of natural head movements for smooth and fast control of the wheelchair, and was well accepted by and integrated into the life of the patients.     

Anomeric Mixtures of D-Xylo-and D-Lyxo-Furanonucleosides: Correlations between their Structures and their Retention Times in HPLC Analysis

Abstract

Rationalization of the intrinsic structural factors which can influence retention times of anomeric D-xylo- and lyxofuranonucleoside analogues in reversed-phase high-performance liquid chromatography (HPLC) has been established.     

Reconstitution in vitro of human gingiva

A model of human gingiva to be used in pharmacological, basic and clinical research was performed in vitro. This model was obtained through a method of low density seeding epithelialization, from a seeding made up of dissociated human gingiva epithelial cells, of a connective tissue equivalent composed of human fibroblasts included in a collagen gel. The histological and ultrastructural data show a multilayered epithelium and the biochemical analysis (two dimensional gel electrophoresis known as NEPHGE) of the cytokeratins used as molecular markers for epithelial differentiation shows the precise differentiation state of the epithelium thus reconstituted. Even though this model has less of a differentiation than that of an in vivo gingival epithelium, it does actually reproduce exactly the structures of the human gingiva namely a multilayered epithelium lying on a connective tissue. It also offers the advantage of cellular elements which are compatible with gingival graftings.     

Anti-HIV Pronucleotides: SATE Versus Phenyl as a Protecting Group of AZT Phosphoramidate Derivatives

Abstract

We comparatively studied the decomposition pathways in CEM cell extract of several PHENYL phosphoramidate diesters of AZT. A correlation between anti-HIV activities in TK^? cell lines and pharmacokinetic data has been observed. This study would help to design corresponding SATE phosphoramidate diesters which revealed potent anti-HIV properties.     

2′-and/or 3Y-Deoxy-β-L-pentofuranosyl Nucleoside Derivatives: Stereospecific Synthesis and Antiviral Activities

Abstract

Several L-enantiomers of nucleoside analogues were stereospecifically synthesized by a multi-step reaction from L-xylose and their antiviral properties were examined in vitro. Two of them, namely β-L-2′,3,′-dideoxycytidine (β-L-ddC) and its 5-fluoro derivative (β-L-FddC) were found to have potent anti-human immunodeficiency virus (HIV) and significant anti-hepatitis B virus (HBV) activities in cell cultures.     

Synthesis and Antiviral Evaluation of the β-L-Enantiomers of Some Thymine 3′-Deoxypentofuranonucleoside Derivatives

Abstract

3′-Deoxy-β-L-erythro- (3), 3′-deoxy-β-L-thero- (6), 2′-fluoro- (7) and 2′-azido-2′,3′-dideoxy-β-L-erythro- (10) pentofuranonucleoside derivatives of thymine have been synthesized and their antiviral properties examined. All these derivatives were stereospecifically prepared by glycosylation of thymine with a suitable peracylated 3-deoxy-L-erythro-pentofuranose sugar (1), followed by appropriate chemical modifications. The prepared compounds were tested for their activity against HIV, but they did not show an antiviral effect.     

DDC- and 3TC-bis(SATE) Monophosphate Prodrugs Overcome Cellular Resistance Mechanisms to HIV-1 Associated with Cytidine Kinase Deficiency

Abstract

A 2,3′-dideoxycytidine (ddC)-resistant T-lymphoid cell line (MOLT-4/8^rddC²⁵⁰), in which deoxycytidine kinase (dCK) gene-expression was decreased when compared with parental cells, has been selected. Cytotoxic and antiretroviral activity of ddC and 3TC was significantly lower in MOLT-4/8^rddC²⁵⁰ than in parental MOLT-4/8 cells. ddC- and 3TC-bis(SATE)phosphotriesters completely overcame cellular resistance mechanisms and showed comparable both cytotoxic and antiretroviral activity in parental and ddC-resistant cells.     

Antiviral Activities of β-Enantiomers of 3′-Substituted-3′-deoxythymidine Analogs

Abstract

Several β-L-3′-substituted-3′-deoxythymidine were stereospecifically synthesized. None of these analogs inhibited HIV-1 nor HBV replication in vitro suggesting that these β-L-pyrimidine derivatives may not be efficiently phosphorylated inside the cells.     

Development of isoporous microslit silicon nitride membranes for sterile filtration applications

The widely used 0.2/0.22 µm polymer sterile filters were developed for small molecule and protein sterile filtration but are not well-suited for the production of large nonprotein biological therapeutics, resulting in significant yield loss and production cost increases. Here, we report on the development of membranes with isoporous sub-0.2 μm rectangular prism pores using silicon micromachining to produce microslit silicon nitride (MSN) membranes. The very high porosity (~33%) and ultrathin (200 nm) nature of the 0.2 µm MSN membranes results in a dramatically different structure than the traditional 0.2/0.22 µm polymer sterile filter, which yielded comparable performance properties (including gas and hydraulic permeance, maximum differential pressure tolerance, nanoparticle sieving/fouling behavior). The results from bacteria retention tests, conducted according to the guidance of regulatory agencies, demonstrated that the 0.2 µm MSN membranes can be effectively used as sterile filters. It is anticipated that the results and technologies presented in this study will find future utility in the production of non-protein biological therapeutics and in other biological and biomedical applications.