Infection of chicken erythrocytes with influenza and other viruses.

Chicken erythrocytes can be infected by the fowl plague (Rostock) strain (FP/R) of influenza type A, Newcastle disease virus (NDV), and Semliki Forest virus (SFV). Only NDV and SFV produced infectious progeny, albeit at low levels. Infection by FP/R was monitored by de novo synthesis of viral proteins, and the proteins synthesized could be identified by comparison with infected chicken fibroblast cells. FP/R synthesized far greater amounts of viral protein than did NDV or SFV.     

Pathogenesis of Herpetic Neuritis and Ganglionitis in Mice: Evidence for Intra-Axonal Transport of Infection

The pathogenesis of acute herpetic infection in the nervous system has been studied following rear footpad inoculation of mice. Viral assays performed on appropriate tissues at various time intervals indicated that the infection progressed sequentially from peripheral to the central nervous system, with infectious virus reaching the sacrosciatic spinal ganglia in 20 to 24 hr. The infection also progressed to ganglia in mice given high levels of anti-viral antibody. Immunofluorescent techniques demonstrated that both neurons and supporting cells produced virus-specific antigens. By electron microscopy, neurons were found to produce morphologically complete virions, but supporting cells replicated principally nucleocapsids. These results are discussed in the context of possible mechanisms by which herpes simplex virus might travel in nerve trunks. They are considered to offer strong support for centripetal transport in axons.     

Detection of turkey rhinotracheitis virus in turkeys using the polymerase chain reaction

Six-week-old turkey poults were infected with the virulent UK/3B/85 strain of TRTV. Tracheal and oesophageal swabs were made every 2 to 3 days from groups of five poults and the RNA extracted. The TRTV RNA was then reverse-transcribed into complementary DNA (cDNA) using an oligonucleotide complementary to the 3' end of the fusion protein (F) mRNA. The cDNA was then used in a polymerase chain reaction (PCR) with an upstream primer to generate a product of approximately 0.5 kbp which was detected by ethidium bromide staining after electrophoresis. In this way, TRTV was detected in both types of swab for 17 to 19 days post-infection, nearly 2 weeks after the peak titres of infectious virus. Swabs which were allowed to dry completely before RNA extraction were as successful as swabs kept wet and extracted almost immediately, useful for when samples are collected in the field. The oligonucleotides amplified the 0.5 kbp product from TRTV strains isolated in six countries over a 13-year period, indicating that they might be usable as 'universal' oligonucleotides for TRTV detection.     

Influence of chemical structure on the fracture behaviour of dimethacrylate composite resins

Previous studies have shown that the fracture resistance of dimethacrylate-based dental composite resins is enhanced by post-curing the matrix. Here, the influence of the chemical nature of the resin matrix is examined by a study of the fracture properties of composite resins formulated from 15 homologous dimethacrylate monomers and filled to 75 wt% with treated silica. The fracture toughness was determined via the double torsion technique and the elastic modulus and flexural strength were measured in flexure. The fracture energy calculated from the fracture toughness and elastic modulus, varied between 60 and 300 J/m2 while the fracture toughness ranged from 0.2 to 2.0 MN/m3/2 and the flexural strength varied from 17 to 111 MPa. The use of a blend of monomers was found to have a synergistic effect on the fracture resistance. Increasing the length of flexible spacer units (methylene or oxyethylene) between the methacrylate groups initially improved the fracture properties; however, beyond a certain length, these properties were impaired.     

Experimental infection of chimpanzees with antihemophilic (factor VIII) materials: recovery of virus-like particles associated with non-A, non-B hepatitis.

Non-A, non-B viral hepatitis was transmitted to four colony-born chimpanzees by infusion of three lots of antihemophilic factor (factor VIII) implicated in the transmission of non-A, non-B hepatitis to two human recipients. All four inoculated animals showed histopathological evidence of viral hepatitis, and all demonstrated significant ALT elevations between seven and one-half weeks after inoculation. Acute-phase plasma from one of the infected chimpanzees (no. 771) was shown to induce non-A, non-B hepatitis in two other chimpanzees approximately three weeks after their inoculation. In addition, an acute-phase open liver wedge biopsy obtained from animal no. 771 was processed and examined by immune electron microscopy (IEM) for virus-like particles with convalescent serum from a serologically confirmed case of non-A, non-B hepatitis. Twenty-five to 30 nm (mean = 27 nm) diameter virus-like particles that were either "full" or "empty" were identified in this liver preparation by IEM. Two additional chimpanzees inoculated with a cesium chloride gradient fraction of an isopycnically banded liver homogenate (animal no. 771) also developed elevated ALT activity two to two and one-half weeks later. Our findings have experimentally verified that commercially produced factor VIII materials can induce non-A, non-B hepatitis in champanzees and that the disease can be subpassaged in these animals by inoculation of either acute-phase plasma or liver. These results also provide evidence for the association of 27 nm-diameter virus-like particles with non-A, non-B viral hepatitis.     

Spontaneous cytotoxicity of murine cells treated with the interferon inducers BRL 5907 and BRL 10739.

The effects of the polyribonucleotide interferon inducers, BRL 5907 and BRL 10739, on the spontaneous cytotoxicity of CBA mouse cells towards the allogeneic lymphoma EL-4, were investigated. Intravenous administration of BRL 5907 and BRL 10739 increased the cytotoxic activity of a non-adherent, theta-negative, surface immunoglobulin-negative cell present in the spleen, but had no effect on cells in the lymph nodes. Spleen cell cytotoxicity was established within 24 h of injection of the polyribonucleotides, but had disappeared by 4 days. In addition, injection of mice with BRL 10739 increased the spontaneous cytotoxicity of a nylon-wool-adherent, theta-positive spleen cell. Intraperitoneal injection of mice with BRL 5907 and BRL 10739 also enhanced the cytotoxic activity of a non-adherent peritoneal exudate cell.     

Phosphorylated KDR is expressed in the neoplastic and stromal elements of human renal tumours and shuttles from cell membrane to nucleus

Vascular endothelial growth factor (VEGF)-A is an important angiogenic factor in establishing the vasculature in renal cell carcinomas (RCCs). Since little is known about VEGF signalling in RCCs, the profile of phosphorylated KDR (pKDR) has been investigated and the intracellular location of the receptor has been examined in the present study. Using two monoclonal antibodies raised against the phosphorylated KDR epitopes (Y1059 and Y1214) known to mediate different VEGF functions, together with a commercial anti-KDR antibody and immunohistochemistry, the expression of pKDR was investigated in a series of normal (n = 25) and neoplastic kidneys (n = 54; clear cell n = 35; papillary n = 10; oncocytomas n = 8). pKDR was present in many tissue elements of both normal and neoplastic renal tissues, with strong expression in the cell membrane, cytoplasm, and nuclei of normal kidney and tumour cells, as well as endothelial cells in tumours of all histological types. Patterns and intensity were similar using both anti-pKDR antibodies. There was no significant correlation in clear cell carcinomas between pKDR expression and age (p = 0.57), tumour size (p = 0.2), gender (p = 0.59), grade (p = 0.2) or histological type (p = 0.36). To delineate further the intracellular processing that might account for the cellular distribution, confocal microscopy was also performed. Antibodies to the different phosphorylated epitopes demonstrated different intracellular staining patterns. This study shows that pKDR is present in a wide variety of renal tumours, suggesting that anti-VEGF therapy might have direct effects on tumour cells. It further suggests that cells traffic pKDR depending on the precise KDR tyrosines that are autophosphorylated in a manner that enables receptor activation to result in different functions.     

Beneficial effects of interleukin-6 in neonatal mouse models of group B streptococcal disease.

Previous studies have shown that tumor necrosis factor alpha (TNF-alpha) plays a pathophysiologic role in sepsis induced in rat pups by group B streptococci (GBS). In this model, TNF-alpha is also partially responsible for the induction of interleukin-6 (IL-6). The present study was undertaken to investigate the role of IL-6 in neonatal BALB/c mice infected with type III GBS. The effect of anti-IL-6 monoclonal antibodies and recombinant IL-6 on lethality and TNF-alpha production was investigated. In mouse pups infected with GBS strain COH1, plasma IL-6 reached levels of 3,067 +/- 955 and 1,923 +/- 891 U/ml when measured at 22 and 48 h, respectively (P < 0.05 compared with uninfected controls). Pretreatment with 25 micrograms of anti-IL-6 antibodies totally prevented the increase in circulating IL-6 bioactivity at both 22 and 48 h after infection (P < 0.05). Treatment with anti-IL-6 also induced a moderate decrease in survival time of mice infected with lethal doses of strains COH1 and COH31, as evidenced by increased lethality (P < 0.05) at 24 to 48 h but not at 96 h. Mouse recombinant IL-6 (12,500 U) given 6 h before challenge with strains COH1 and COH31 consistently increased survival time, as evidenced by decreased (P < 0.05) lethality at 48 to 72 h but not at 96 h. The effects of IL-6 pretreatment were dose dependent, since no protection was observed with doses lower than 12,500 U. In addition, no effects on lethality were noted when IL-6 was given at the time of challenge or at later times. TNF-alpha elevations (P < 0.05 compared with uninfected controls) were measured at 12, 22, and 48 h after challenge with strain COH1 (68 +/- 28, 233 +/- 98, and 98 +/- 34 U, respectively). Pretreatment with IL-6 significantly (P < 0.05) decreased plasma TNF-alpha levels at 12 and 22 h, with 55 and 69% inhibitions, respectively. Anti-IL-6 had an opposite effect, as evidenced by a 145% increase (P < 0.05) in TNF-alpha levels at 48 h after challenge. Collectively, our data are compatible with the hypothesis that IL-6 is involved in negative feedback regulation of plasma TNF-alpha levels in experimental GBS sepsis. In this model, IL-6 pretreatment can increase survival time. Future studies will be needed to investigate the mechanisms underlying this effect.     

Cardiovascular responses of women with chronic fatigue syndrome to stressful cognitive testing before and after strenuous exercise

OBJECTIVE: The purpose of this study was to compare the cardiovascular responses of patients with chronic fatigue syndrome (CFS) to healthy control subjects when performing stressful cognitive tasks before and after strenuous exercise. METHOD: Beat-by-beat blood pressure and electrocardiogram were recorded on 19 women with CFS and 20 healthy nonexercising (ie, sedentary) women while they performed cognitive tests before, immediately after, and 24 hours after incremental exercise to exhaustion. RESULTS: Diminished heart rate (p <.01) and systolic (p <.01) and diastolic (p <.01) blood pressure responses to stressful cognitive testing were seen in patients with CFS when compared with healthy, sedentary controls. This diminished stress response was seen consistently in patients with CFS across three separate cognitive testing sessions. Also, significant negative correlations between self-ratings of CFS symptom severity and cardiovascular responses were seen (r = -0.62, p <.01). CONCLUSIONS: Women with CFS have a diminished cardiovascular response to cognitive stress; however, exercise did not magnify this effect. Also, the data showed that the patients with the lowest cardiovascular reactivity had the highest ratings of CFS symptom severity, which suggests that the individual response of the patient with CFS to stress plays a role in the common complaint of symptoms worsening after stress.