Showing papers by "David Long published in 1990"

Cysteine mutants of herpes simplex virus type 1 glycoprotein D exhibit temperature-sensitive properties in structure and function.

Abstract: We previously constructed seven mutations in the gene for glycoprotein D (gD) of herpes simplex virus type 1 in which the codon for one of the cysteine residues was replaced by a serine codon. Each of the mutant genes was cloned into a eucaryotic expression vector, and the proteins were transiently expressed in mammalian cells. We found that alteration of any of the first six cysteine residues had profound effects on protein conformation and oligosaccharide processing. In this report, we show that five of the mutant proteins exhibit temperature-sensitive differences in such properties as aggregation, antigenic conformation, oligosaccharide processing, and transport to the cell surface. Using a complementation assay, we have now assessed the ability of the mutant proteins to function in virus infection. This assay tests the ability of the mutant proteins expressed from transfected plasmids to rescue production of infectious virions of a gD-minus virus, F-gD beta, in Vero cells. Two mutant proteins, Cys-2 (Cys-106 to Ser) and Cys-4 (Cys-127 to Ser), were able to complement F-gD beta at 31.5 degrees C but not at 37 degrees C. The rescued viruses, designated F-gD beta(Cys-2) and F-gD beta(Cys-4), were neutralized as efficiently as wild-type virus by anti-gD monoclonal antibodies, indicating that gD was present in the virion envelope in a functional form. Both F-gD beta(Cys-2) and F-gD beta(Cys-4) functioned normally in a penetration assay. However, the infectivity of these viruses was markedly reduced compared with that of the wild type when they were preincubated at temperatures above 37 degrees C. The results suggest that mutations involving Cys-106 or Cys-127 in gD-1 confer a temperature-sensitive phenotype on herpes simplex virus. These and other properties of the cysteine-to-serine mutants allowed us to predict a disulfide bonding pattern for gD.

Hematological and biochemical changes during a short triathlon competition in novice triathletes

Abstract: Short-course ‘sprint’ triathlons have become popular in recent years, often as a precursor to the longer full-course triathlons We undertook a study investigating the haematological and biochemical changes that occur in novice triathletes between the start and finish and after each of the three legs of a short sprint triathlon involving swimming, cycling and running The changes that occurred in the triathlon included a significant (P<0003) decrease in weight from 717 kg, SD 79 to 703 kg, SD 76 Throughout the time span of the triathlon, the white blood cell count increased significantly (P<0001), as did the platelet count (P<0005) and plateletcrit (P<0001) There were no significant changes during the period of the race in any of the other haematological variables measured The biochemical variables measured were glucose, triglycerides, sodium, potassium, calcium, lactate dehydrogenase, creatinine and aspartate aminotransferase Triglyceride, calcium and potassium values did not change between the pre- and post-race samplings All other biochemical parameters showed a significant change (P<005 or better) Changes that occurred in the haematological and biochemical parameters between stages were many and varied There was also a significant change in plasma volume during the swimming event (P< 0001), but this returned to normal during the later stages of the triathlon In conclusion the changes that occurred during the triathlon were many and were similar to those reported elsewhere in the literature for longer events The novice triathletes who participated, found this short triathlon to be as stressful as the full-course triathlon is for the more experienced athlete We feel, however, that this type of event is useful as a precursor to the longer type of events

The role of arachidonic acid and oxygen radicals on cerebromicrovascular endothelial permeability.

Abstract: Arachidonic acid release from tissue membranes and/or formation of free radical species have been considered to affect blood-brain barrier permeability and formation of brain oedema. To determine whether exogenous arachidonic acid or H2O2 may alter blood-brain barrier permeability, we examined their effect on cultured endothelium derived from cerebral microvessels of human and animals. Release of 51Cr from labeled endothelium exposed to these substance was used as a main marker for the assessment of endothelial injury. The results of these studies indicate that endothelial cells (EC) are susceptible to exogenous arachidonic acid or H2O2 insult irrespective of their origin. However human endothelial cells are less affected than animal EC by H2O2-generated systems. The findings suggest that a disturbance of the existing balance between the endogenous antioxidant properties of EC and exogenous oxidant leads to EC injury.