Epstein-Barr virus (EBV)-lymphoid cell interactions. I. Quantification of EBV particles required for the membrane immunofluorescence assay and the comparative expression of EBV receptors on different human B, T and null cell lines

We report data on the number of Epstein-Barr virus (EBV) particles required to detect virus binding to target cells (Raji or BJA-B) by means of membrane immunofluorescence (MIF). After determining the optimum conditions for the MIF assay the following aspects of EBV-lymphoid cell interactions were examined: (i) binding of two different strains of EBV to various types of human lymphoid cell lines, (ii) expression of receptors for both EBV and complement on these lines and (iii) induction of EBV-induced nuclear antigen (EBNA) in the different target cells used. The results showed that a minimum of about 2.7 x 10(3) enveloped virus particles/cell were required for an optimum visualization of EBV binding to the target cells tested, and that a lymphoid cell may bear receptors for one prototype strain of EBV but not for the other. A number of cell lines, particularly those of T and null type which express EBV receptors, did not synthesize EBNA, thus indicating that these lines were resistant to EBV infection. Several of these lines, although expressing cell surface EBV receptors, lacked complement receptors.

Age related differences in cellular immune response to vaccine induced rubella infection

Employing the techniques of in-vitro lymphocyte transformation (LTF) and using Putnam strain of rubella virus as the antigen, the development of rubella specific cellular immune response was studied in different age groups of rubella seronegative normal subjects at various intervals after subcutaneous administration of HPV=77/DE5 live attenuated rubella vaccine. The rubella specific lymphocyte response in children ranging in age from two to twelve years was characterized by significant LTF activity at two months, followed by a gradual decrease. The response in adult subjects 18 to 35 years of age showed a slight delay initially in the appearance and the maximum LTF activity appeared to be 3--4 fold lower (P less than 0.01) than observed in the children. No difference was observed in the maximum antibody titers to rubella virus between these two groups of subjects. These observations suggest that the age related differences in the lymphoproliferative responses might be associated with adverse effects which are known to occur more frequently in adolescent and older patients than in childhood population after vaccine induced rubella infection.

Cellular adaptations of the ventilatory muscles to a chronic increased respiratory load

It is not known whether cellular adaptations of the ventilatory muscles are induced by increased respiratory loads. A chronic respiratory load was produced in rats by tracheal banding. Five weeks after the imposition of this increased load, biochemical and histochemical analyses were performed on the diaphragm and intercostal muscles. The oxidative capacity, as indicated by succinate dehydrogenase (SDH) activity, increased 38% in the diaphragm. The capacity for beta-oxidation fatty acids, as indicated by 3-hydroxy-acyl-CoA dehydrogenase (HADH) activity, increased 29%. The glycolytic capacity, as indicated by phosphofructokinase (PFK) activity, did not change. Similar enzymatic adaptations were observed in the intercostal muscles. The proportion of slow-twitch muscle fibers, as indicated by the myofibrillar adenosine triphosphatase (ATPase) stain, increased in the diaphragm, but not in the intercostal muscles. Thus, these ventilatory muscles responded with an increase in their oxidative capacity, and the diaphragm reponded with an increase in the proportion of muscle fibers having the myofibriller ATPase staining characteristic of slow-twich fibers. We conclude that cellular adaptations are induced in the ventilatory muscles by chronic increased respiratory loads.

Drug therapy in intermittent claudication: an objective assessment of the effects of three drugs on patients with intermittent claudication

It has been suggested that, by reducing the viscosity of blood, flow through capillaries is increased with consequent improvement in the symptoms of patients with peripheral vascular disease. We examined the effects of treatment with drugs purported to reduce blood viscosity to test the validity of this claim. Measurements of viscosity and the rate of blood flow to the leg were made in a group of patients before and after treatment with three different drugs--tetranicotinoylfructose (Bradilan), oxypentifylline (Trental) and cinnarizine (Stugeron). All patients had intermittent claudication in one leg and the distribution of arteriosclerosis was similar in each patient. After treatment there was little or no change in blood viscosity and no change in the rate of flow recorded in the symptomatic legs. We did not find any objective evidence to support the use of these drugs in patients with intermittent claudication.

Presence of Epstein-Barr virus receptors, but absence of virus penetration, in cells of an Epstein-Barr virus genome-negative human lymphoblastoid T line (Molt 4)

This paper reports a unique type of interaction of Epstein-Barr virus (EBV) with an EBV receptor-positive, genome-negative human lymphoid T cell line (Molt 4), which can be summarized as follows. Although Molt 4 cells express receptors for EBV, they appear to block the penetration of this virus. These observations are derived from combined studies with immunofluorescence and electron microscopy. It is possible that T cell lines bearing receptors for EBV may express such a control on virus penetration.

Pulsatile changes of electrical impedance in the lower limb

The ratio of the pulsatile and the mean value of the volume of blood flowing through the calves of normal subjects with each heart beat was calculated from electrical impedance changes during venous occlusion plethysmography. Measurements made concurrently by proven Doppler ultrasound techniques did not correlate with ratios derived from the impedance measurements. The pulsatile change in electrical impedance in the limbs appears to be due more to changes of resistance in the blood than to pulsatile changes in the volume of the limb.