Allergic Complications of Meningococcal Disease II—Immunological Investigations

Immunological investigation of four patients with meningococcal meningitis who developed arthritis or cutaneous lesions showed circulating meningococcal antigen at the time of presentation in each patient. It was cleared from the circulation over the next few days. Circulating antibody was detectable in three of the four patients about a week after the onset of the illness. A marked fall in the serum C₃ level occurred in two patients at about that time. Deposits of meningococcal antigen, immunoglobulin, and C₃ were detected in the synovial fluid white cells of the two patients studied and in one of three skin biopsies examined. These findings suggest that the arthritis and cutaneous lesions of meningococcal meningitis may be due to immune complex formation.     

Replication of cauliflower mosaic virus DNA in leaves and suspension culture protoplasts of cotton

Cauliflower mosaic virus (CaMV) replicated in protoplasts and in inoculated leaves of the non-host, cotton (Gossypium hirsutum, L.). Protoplasts prepared from suspension-cultured cotton cells were infected by incubation with liposome-encapsulated CaMV virions. During a 1-week culture period the amount of CaMV nucleic acid as detected by nucleic acid hybridization in the protoplasts increased significantly regardless of whether or not the protoplasts contained vacuoles. In leaves inoculated with CaMV virions or CaMV DNA, viral DNA sequences were found by leaf skeleton hybridization to be located in small circular areas. DNA extracted from ultracentrifugal pellets of homogenates of inoculated leaves contained circular, gapped CaMV DNA only when inocula contained CaMV virions, CaMV DNA, or partial nested dimer CaMV plasmid DNA. When plants had been heavily watered, the CaMV DNA recovered contained degraded CaMV DNA. The results suggest that the host range limitation for CaMV is not due to an inability to replicate or spread locally in inoculated leaves.     

Inhibition of the oxygen-induced contraction of the isolated human umbilical artery by indomethacin, flurbiprofen, aspirin and drugs modifying Ca2+ disposition

In this study we have quantified the potency of three cyclo-oxygenase inhibitors, indomethacin, flurbiprofen and aspirin to reduce the vasoconstriction of isolated strips of human umbilical artery (HUA) to changing the oxygen-tension (PO2) of the bathing medium. The inhibitory potencies (IC50) of indomethacin and flurbiprofen were similar (IC50 = 2.1 x 10(-9) M and 7.6 x 10(-9) M respectively) while aspirin (IC50 = 2.5 x 10(-5) M) was approximately 12,000 fold less potent than indomethacin. At the physiological PO2 of 15 mmHg the isolated HUA was found to have an inherent cyclo-oxygenase induced tone since either reducing the PO2 from 15 to OmmHg or adding cyclo-oxygenase inhibitors caused vasorelaxation. O2-induced contractions were partly dependent on extracellular Ca2+: nifedipine and Bay K 8644 inhibited and enhanced oxygen-induced contractions, respectively, but did not have a significant effect on calcium-dependent 5-hydroxy-tryptamine-induced (5-HT) contractions. Therefore cyclo-oxygenase products and 5-hydroxytryptamine-induced contractions of the HUA may both utilise extracellular calcium but through different processes.     

Platelet and cardiovascular activity of the hydantoin BW245C, a potent prostaglandin analogue

The platelet anti-aggregating, cardiovascular and gastro-intestinal actions of a hydantoin prostaglandin analogue, BW245C have been compared with prostacyclin and PGD2 in several species. In human plasma in vitro, BW245C was 0.2 times as active as prostacyclin and 8 times as active as PGD2 in inhibiting platelet aggregation. In rat and rabbit plasma, BW245C was only weakly active but was more potent in sheep and horse plasma. Since the activity of PGD2 varied in a parallel fashion, BW245C may interact with PGD2 binding sites on platelets. The potency of BW245C as a vasodepressor also varied between species, being 0.5, 0.1, 0.06 and less than 0.02 times as active as prostacyclin in the anaesthetised dog, monkey, rat and rabbit respectively. The relative activity of BW245C as an inhibitor of platelet aggregation ex vivo was more comparable, being 0.08, 0.04 and 0.05 times as active as prostacyclin following intravenous infusion in the rabbit dog and monkey respectively. In the rabbit, BW245C was a highly selective platelet inhibitor with minimal cardiovascular actions, whereas in the dog and monkey, BW245C lowered BP in anti-aggregating doses. The potent platelet anti-aggregating actions of BW245C following parenteral or oral administration makes this hydantoin a potentially-useful anti-thrombotic prostaglandin analogue.     

The behaviour of 14C profiles in Helianthus seedlings

Summary The log. ¹⁴C activity/distance profile in the stems of Helianthus seedlings consists of two main parts: region 1, the linear advancing front and region 2, which is also linear but with a less steep slope. As the front passes down the stem, the slope of region 1 remains constant but the amplitude of the front becomes attenuated. The attenuation increases with temperature. The apparent velocity of the profile, which can be derived from the position of the front, is also temperature dependent. Small amounts of ¹⁴C occur in the stem ahead of the profile; these amounts increase with a rise of temperature. Region 2 behaves differently: its slope decreases steadily with time but it is insensitive to temperature. The behaviour of this region is dependent on the movement of tracer into an immobile fraction as well as on the longitudinal movement of tracer in the translocation stream.     

Biological and molecular variability of human immunodeficiency virus type 2 isolates from The Gambia.

Seven new human immunodeficiency virus type 2 (HIV-2) isolates (CBL-20 to CBL-26) from The Gambia were characterized. Their cytopathogenicity and growth in vitro correlated with the severity of clinical disease. CBL-22 was highly sensitive to neutralization by HIV-2 sera and was cross-neutralized by some HIV-1 sera. These findings, the differing sizes of envelope glycoproteins of individual isolates, and the sequence analysis of amplified regions of the viral DNAs show that these HIV-2 isolates from one geographical region in West Africa exhibit biological and genome variability comparable to that observed for HIV-1.     

Involvement of the endoplasmic reticulum in the assembly and envelopment of African swine fever virus.

African swine fever (ASF) virus is a large enveloped DNA virus assembled in the cytoplasm of cells. In this study, the membrane compartments involved in the envelopment of ASF virus were investigated. A monoclonal antibody recognizing p73, the major structural protein of ASF virus, was generated to analyze the binding of p73 to membranes during the assembly of the virus. Approximately 50% of the intracellular pool of p73 associated with membranes as a peripheral membrane protein. Binding was rapid and complete within 15 min of synthesis. Subcellular membrane fractionation showed that newly synthesized p73 molecules cosedimented with endoplasmic reticulum (ER) membranes and remained associated with the ER during a 2-h chase. A similar distribution on gradients was recorded for p17, a structural membrane protein of ASF virus. The results suggested that the ER was involved in the assembly of ASF virus. A protease protection assay demonstrated a time-dependent envelopment of the membrane bound, but not cytosolic, pool of p73. Envelopment of p73 took place 1 h after binding to membranes and was completed 1 h before the first detection of p73 in virions secreted from cells. Envelopment was unaffected by brefeldin A and monensin, drugs that block membrane transport between the ER and Golgi. Taken together the results provide evidence for the binding of ASF virus structural proteins to a specific membrane compartment and implicate a role for the ER in the assembly and envelopment of ASF virus.