Immunological and pharmacological analysis of the primary and secondary reagin response to Nippostrongylus brasiliensis in the rat

When systemic anaphylaxis has been induced in rats infected once with the nematode, Nippostrongylus brasiliensis, the gross pathological lesions are found in the small intestine (`early' anaphylaxis). When systemic anaphylaxis is induced in rats infected four times, these lesions appear predominantly in the lungs (`late' anaphylaxis). The reasons for the change in localization of the lesions have been studied.

Reaginic antibodies are involved in both `early' and `late' anaphylaxis but there was no difference in the physicochemical and biological properties of circulating reagins taken after one or after four infections. In particular, no differences in their preference for a distinct tissue structure was detected because, in rats given either `early' or `late' reaginic antibody, passive systemic anaphylaxis resulted in lesions restricted to the small intestine. The amount of `blocking' antibody increased after several successive infections and did not explain the decrease in sensitivity to systemic anaphylaxis which occurred in rats infected twice or three times.

Differences in the degree of anaphylactic sensitization of a given tissue were assessed by measuring titres of local reaginic antibody and concentrations of tissue histamine. Following an initial infection, anaphylactic sensitization is highest along the small intestine; following several successive infections, anaphylactic sensitization is especially high in lung tissue. It is suggested that the changes in the local site and degree of anaphylactic sensitization are due to the increase in immunity of the host which allows the parasite to migrate to the lungs but not to reach the intestine.

     

Long-term potentiation of thalamic input to the motor cortex induced by coactivation of thalamocortical and corticocortical afferents

1. Intracellular recordings were obtained from neurons in the motor cortex (MCx), in which excitatory postsynaptic potentials (EPSPs) were evoked by microstimulation of the somatosensory cortex (SCx) and the ventrolateral nucleus (VL) of the thalamus. The effects of combined tetanic stimulation of SCx and VL on the amplitudes of these EPSPs were studied. 2. Amplitudes of both corticocortical (CC) and thalamocortical (TC) EPSPs were potentiated after combined tetanic stimulation. This potentiation occurred exclusively in neurons that were located in the superficial layers (II/III) and that received direct input from both the SCx and VL, with both inputs synapsing in close proximity to each other. In all cases, the potentiation lasted until the electrode went out of the cell (21 +/- 25 min, mean +/- SD) the longest being 90 min. We therefore refer to this potentiation as long-term potentiation (LTP). 3. Tetanic stimulation of the thalamus only did not produce LTP in neurons receiving direct input from the VL. 4. LTP was not induced in either CC or TC EPSPs in neurons located in layer V and/or in neurons receiving long-latency CC EPSPs. 5. It is concluded that TC input from the VL to the MCx is potentiated only when coactivated with the CC input from the SCx.     

Lectins in diagnostic microbiology

Current literature suggests that lectins are becoming valuable reagents for the laboratory identification of infectious agents. The identification of bacteria, fungi, or protozoa may be confirmed if they bind to or agglutinate with certain lectins. Assay kits utilizing specific lectin agglutination reactions, coupled with conventional enzyme determinations, have been proposed for several bacteria. Factors such as specificity, stability, assay rapidity, and costs combine to make lectins attractive diagnostic reagents. It is likely that the use of lectins in diagnostic microbiology will continue to grow.     

Comparison of the effect of refrigerated versus room temperature media on the isolation of Neisseria gonorrhoeae from genital specimens.

We evaluated the effect of medium temperature at the time of inoculation on the isolation of Neisseria gonorrhoeae from urethral and cervical swabs. There were no major differences in the isolation rates of 176 positive cultures on cold or warm media. Colonies tended to be larger and more numerous on room temperature plates after 24 h; however, colonies on most refrigerated plates were easily recognized at 24 h, and growth was essentially the same on both plates after 48 h.     

Human polyspecific immunoglobulin attenuates group A streptococcal virulence factor activity and reduces disease severity in a murine necrotizing fasciitis model

Objectives

Streptococcus pyogenes causes life-threatening invasive infections including necrotizing fasciitis (NF). Current treatment guidelines recommend the use of a cell-wall–active antibiotic combined with a protein synthesis inhibitor and surgical debridement in NF patients. Adjunctive therapy with intravenous immunoglobulin (IVIG) has been proposed for superantigen-associated streptococcal toxic shock syndrome. So far, benefits of IVIG treatment remain unclear and prospective clinical studies are scarce. Thus, we aimed to assess the effects of IVIG on virulence factor activity in vitro, ex vivo in patients and in vivo in a NF mouse model.

Increased incidence of numerical chromosome abnormalities in spermatozoa injected into human oocytes by ICSI

The potential risk of transmitting chromosomally abnormal spermatozoa from infertile males into oocytes through intracytoplasmic sperm injection (ICSI) has prompted us to investigate the male pronuclei of tripronuclear zygotes (3PN) obtained after ICSI. To specify the type of anomalies, we used triple colour fluorescent in-situ hybridization (FISH) with three specific probes for chromosomes X, Y and 18. From a total of 163 paternal complements of ICSI-3PN zygotes, 90 (55.2%) had Y-chromosome signals. Eighty-three of these were normal, four had the disomy XY and three were diploid. In the remaining 73 ICSI-3PN zygotes without Y-chromosome signals, the origin of paternal pronuclei was extrapolated through chromosome constitution of the first polar body. Five anomalies were found in this group of zygotes, giving a total rate of numerical chromosome aberrations for fertilizing spermatozoa of 7.4%. In contrast to ICSI, only two disomies (1.5%) were found in the control group of IVF-3PN zygotes. Compared with the incidence of chromosome anomalies between paternal-derived pronuclei of ICSI- and IVF-3PN zygotes, the difference was statistically significant (P < 0.025). This study provides the first direct evidence of a higher incidence of numerical chromosome anomalies in sperm-fertilized human oocytes after ICSI.     

Novel murine clonal cell lines either express slow or mixed (fast and slow) muscle markers following differentiation in vitro

We have investigated whether the phenotype of myogenic clones derived from satellite cells of different muscles from the transgenic immortomouse depended on muscle type origin. Clones derived from neonatal, or 6- to 12-week-old fast and slow muscles, were analyzed for myosin and enolase isoforms as phenotypic markers. All clones derived from slow-oxidative muscles differentiated into myotubes with a preferentially slow contractile phenotype, whereas some clones derived from rapid-glycolytic or neonatal muscles expressed both fast and slow myosin isoforms. Thus, muscle origin appears to bias myosin isoform expression in myotubes. The neonatal clone (WTt) was cultivated in various medium and substrate conditions, allowing us to determine optimized conditions for their differentiation. Matrigel allowed expressions of adult myosin isoforms, and an isozymic switch from embryonic alpha- toward muscle-specific beta-enolase, never previously observed in vitro. These cells will be a useful model for in vitro studies of muscle fiber maturation and plasticity.     

Exercise-induced metallothionein expression in human skeletal muscle fibres

Exercise induces free oxygen radicals that cause oxidative stress, and metallothioneins (MTs) are increased in states of oxidative stress and possess anti-apoptotic effects. We therefore studied expression of the antioxidant factors metallothionein I and II (MT-I + II) in muscle biopsies obtained in response to 3 h of bicycle exercise performed by healthy men and in resting controls. Both MT-I + II proteins and MT-II mRNA expression increased significantly in both type I and II muscle fibres after exercise. Moreover, 24 h after exercise the levels of MT-II mRNA and MT-I + II proteins were still highly increased and the MT-II mRNA expression reached a 15-fold increase. As expected, immunohistochemical detection of malondialdehyde (MDA) and nitrotyrosine (NITT) showed that formation of free radicals and oxidative stress were clearly increased in exercising muscle peaking shortly after the end of exercise in both type I and II muscle fibres. This is the first report demonstrating that MT-I + II are significantly induced in human skeletal muscle fibres following exercise. As MT-I + II are antioxidant factors that protect various tissues during pathological conditions, the MT-I + II increases post exercise may represent a mechanism whereby contracting muscle fibres are protected against cellular stress and injury.     

The expression of the syn- gene of herpes simplex virus type 1. II. Requirements for macromolecular synthesis.

The fusion of cells infected with a single-step syn^? mutant of the Glasgow 17 strain of herpes simplex virus type 1 (HSV-1) is independent of the production of infectious virus. The fusion response of infected BHK cells occurs between 4 and 8 hr postinfection. Prior to this time, synthesis of both RNA and protein is required. The RNA required for the full expression of the syn^? phenotype is synthesized by 4 hr postinfection, while the protein required for the full expression of the syn^? phenotype is synthesized by 6 hr postinfection. In the presence of 2-deoxy-d-glucose (DOG), neither cell fusion nor the production of infectious virus occurs. As monitored by electrophoresis on sodium dodecyl sulfate-polyacrylamide gels, essentially all of the virus proteins are produced in the presence of DOG. However, the bands corresponding to glycoproteins are absent with a concomitant appearance of bands with faster mobilities. This observation suggests that the presence of DOG prevents the complete glycosylation of glycoproteins. These results support the idea that glycoproteins are required for cell fusion as well as for the production of infectious virus.