Observational learning and the fearful child: influence of peer models on swimming skill performance and psychological responses

This study examined the role of peer mastery and coping models on children's swimming skills, fear, and self-efficacy. Children (N = 24; M age = 6.2 years), who were identified as fearful of the water, were matched to control, peer-mastery, or peer-coping model conditions. Day 1 included a preintervention assessment. Days 2-4 included exposure to model conditions followed by a 20-min swimming lesson, Day 5 consisted of postintervention assessments, and a follow-up test was conducted 4 days later. Data were analyzed in a series of 3 x 3 (Model Type x Assessment Period) repeated measures analyses of variance on the dependent variables. Results revealed differences between modeling and control groups at postintervention and follow-up, but the small sample size and large within-group variability compromised many statistically significant findings. Calculation of effect sizes indicated moderate-to-large pre- to posintervention differences between control and modeling groups on skill, self-efficacy, and fear of swimming. These findings suggest that a modeling intervention combined with swimming lessons is a more effective behavior change agent for fearful children than swimming lessons alone.

Molecular evidence for distinct genotypes of monkey B virus (herpesvirus simiae) which are related to the macaque host species

Although monkey B virus (herpesvirus simiae; BV) is common in all macaque species, fatal human infections appear to be associated with exposure to rhesus macaques (Macaca mulatta), suggesting that BV isolates from rhesus monkeys may be more lethal to nonmacaques than are BV strains indigenous to other macaque species. To determine if significant differences that would support this supposition exist among BV isolates, we compared multiple BV strains isolated from rhesus, cynomolgus, pigtail, and Japanese macaques. Antigenic analyses indicated that while the isolates were very closely related to one another, there are some antigenic determinants that are specific to BV isolates from different macaque species. Restriction enzyme digest patterns of viral DNA revealed marked similarities between rhesus and Japanese macaque isolates, while pigtail and cynomolgus macaque isolates had distinctive cleavage patterns. To further compare genetic diversity among BV isolates, DNA sequences from two regions of the viral genome containing genes that are conserved (UL27 and US6) and variable (US4 and US5) among primate alphaherpesviruses, as well as from two noncoding intergenic regions, were determined. From these sequence data and a phylogenetic analysis of them it was evident that while all isolates were closely related strains of BV, there were three distinct genotypes. The three BV genotypes were directly related to the macaque species of origin and were composed of (i) isolates from rhesus and Japanese macaques, (ii) cynomolgus monkey isolates, and (iii) isolates from pigtail macaques. This study demonstrates the existence of different BV genotypes which are related to the macaque host species and thus provides a molecular basis for the possible existence of BV isolates which vary in their levels of pathogenicity for nonmacaque species.

Single-field total lymphoid irradiation in the treatment of refractory rejection after heart transplantation

Nine heart transplant recipients were treated with single-field total lymphoid irradiation (TLI) for early (<1 year) or late (>1 year) rejection that was refractory to multiple regimens of immunosuppressive therapy. For patients with early rejection (n = 6), the rejection frequency (rejections/patient/month) decreased from pre-TLI of 1.63 to post-TLI of .02 (p < .001), and for patients with late rejection (n = 3), the rejection frequency decreased from pre-TLI of .23 to post-TLI of .05 (p < .02). The reduced rejection frequencies have been maintained for a mean follow-up of 28.6 (8 to 78) months, and adverse events during or late after TLI were uncommon. Single-field TLI is a safe and effective technique in the management of refractory rejection early or late after heart transplantation.

Child psychosis due to hypothyroidism

Images

Evolution of the major pilus gene cluster of Haemophilus influenzae

Haemophilus influenzae is a ubiquitous colonizer of the human respiratory tract and causes diseases ranging from otitis media to meningitis. Many H. influenzae isolates express pili (fimbriae), which mediate adherence to epithelial cells and facilitate colonization. The pilus gene (hif) cluster of H. influenzae type b maps between purE and pepN and resembles a pathogenicity island: it is present in invasive strains, absent from the nonpathogenic Rd strain, and flanked by direct repeats of sequence at the insertion site. To investigate the evolution and role in pathogenesis of the hif cluster, we compared the purE-pepN regions of various H. influenzae laboratory strains and clinical isolates. Unlike Rd, most strains had an insert at this site, which usually was the only chromosomal locus of hif DNA. The inserts are diverse in length and organization: among 20 strains, nine different arrangements were found. Several nontypeable isolates lack hif genes but have two conserved open reading frames (hicA and hicB) upstream of purE; their inferred products are small proteins with no data bank homologs. Other isolates have hif genes but lack hic DNA or have combinations of hif and hic genes. By comparing these arrangements, we have reconstructed a hypothetical ancestral genotype, the extended hif cluster. The hif region of INT1, an invasive nontypeable isolate, resembles the hypothetical ancestor. We propose that a progenitor strain acquired the extended cluster by horizontal transfer and that other variants arose as deletions. The structure of the hif cluster may correlate with colonization site or pathogenicity.

The development of topography in the hamster geniculo-cortical projection

Precise point-to-point connectivity is the basis of ordered maps of the visual field. The immaturity of the newborn hamster's visual system has allowed us to examine emerging topography in the geniculo-cortical projection well before thalamic axons have reached their cortical target, layer IV. Using anterograde transneuronal labeling with wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP), we visualized the ingrowth of the whole population of geniculate fibers in the neonatal hamster. Two days after birth (P2), the bulk of the fibers is in the deep cortical layers and the subplate. At the same age, injections of paired retrograde tracers (red and green fluorescent latex microspheres) into area 17 reveal an unordered projection from the dorsal lateral geniculate nucleus (dLGN) to cortex. Individual labeled cells are found throughout the dLGN, and quantitative analysis reveals no segregation of the red and the green populations. At P6, when the pattern of geniculate back label appears ordered and essentially adult-like, geniculate fibers have reached layer IV. The role of selective cell death in this process was investigated by making a tracer injection at P2 and allowing the animals to survive to P6 or P12, when the map is mature. The results show early labeled neurons that made inappropriate connections when the projection was scattered surviving through the period of geniculate cell death. We conclude that the geniculo-cortical map develops from an initially unordered projection to the subplate and the lower cortical layers. Selective cell death appears not to contribute significantly to this process.

Genetic analysis of the essential components of the immunoprotective response to infection with Eimeria vermiformis

The immune responses generated after infection with Eimeria spp. are complex, include both cellular and humoral components, and lead to protection against re-infection. To facilitate the rational development of the next generation of anticoccidial vaccines it is important that the nature of the immunoprotective response against infection with Eimeria spp. is determined. In this brief report we discuss results that were obtained using a combination of genetic and cellular approaches to dissect the essential immune effector components that operate against infection with Eimeria vermiformis. Mice rendered deficient of immune function by targeted gene disruption at a variety of immune loci represent an integral component of our studies and include those with targeted gene disruption at loci that encode the B- and T-cell receptors (BCR, TCR), antigen presentation molecules and immune-effector molecules. Our studies demonstrated that TCR-alpha-beta + T cells are essential for immunoprotection during both primary and secondary infection. Moreover, during primary infection the major effector cell type is a population of major histocompatibility complex class II-restricted, interferon-gamma-producing TCR-alpha-beta T cell consistent with a T helper 1 phenotype. In addition, there is a supplementary role for another class of cells (presumably T cells) that are restricted to either non-classical antigen presentation molecules or classical major histocompatibilty complex class I loaded via an atypical pathway. Mice with a deficiency in interleukin-6 were slightly more susceptible to primary infection than intact animals, consistent with the reported effects of interleukin-6 upon the generation of T helper 1-type responses in vivo. In terms of the host response to re-infection, TCR-alpha-beta T cells were essential for immunity, but the requirement for specific cell subsets and effector mechanisms was much less stringent. Mice deficient in gamma-delta T cells, classical major histocompatibility complex class I, non-classical antigen presentation pathways, the cytokines interferon-gamma, interleukin-4, interleukin-6 and the cytolytic effector molecules perforin or FasL were completely immune to secondary infection. Moreover, major histocompatibility complex class II-deficient I-A-beta-/- mice were capable of mounting a substantial response to secondary infection, manifest by a 95% reduction in oocyst output compared with primary infection. These data have important consequences for the development of immune intervention strategies and indicate that vaccine development may be targeted toward the generation of a wider range of effector mechanisms than those that operate during primary infection.

Mouse parvovirus infection potentiates allogeneic skin graft rejection and induces syngeneic graft rejection

BACKGROUND

The recently identified autonomous mouse parvovirus designated mouse parvovirus-1 (MPV-1) persists in adult BALB/c mice for at least 9 weeks, infects lymphoid tissues, interferes with the ability of cloned T cells to proliferate, and exhibits immunomodulatory properties. As a consequence of these findings, the present studies were undertaken to characterize further the inmunomodulatory effects of MPV-1 on T cell-mediated immune responses in vivo and in vitro.

METHODS

To evaluate the effect of MPV-1 infection on CD8+ T cell-mediated responses, BALB/c-H2dm2 mice were infected after transplantation of allogeneic BALB/c skin.

RESULTS

MPV-1 potentiated the rejection of allogeneic skin grafts. This potentiation was not a result of virus infecting the cellular or vascular component of the graft as determined by in situ hybridization, but was mediated by T cells. However, the proliferative capacity of alloantigen-reactive lymphocytes from graft-sensitized infected mice was diminished. MPV-1 also induced the rejection of syngeneic skin grafts, and T cells from these infected graft-sensitized mice lysed syngeneic P815 target cells.

CONCLUSIONS

These results suggest that MPV-1 infection of skin-grafted mice may disrupt normal mechanisms of peripheral tolerance and provide a unique model to study virus-induced autoimmunity.

Treatment of septic shock with immunotherapy

Sepsis is the thirteenth leading cause of death in the United States. Despite increased knowledge about its pathophysiology, availability of powerful antibiotics, and advanced diagnostic and monitoring techniques, mortality rates have not changed significantly over the past 30 years. Immunotherapy may improve outcome in the critically ill with sepsis, although trial results have been disappointing to date.

Development of laminar distributions of kainate receptors in the somatosensory cortex of mice

Kainate receptors were present at birth in the murine somatosensory cortex as revealed by quantitative in vitro autoradiography. During the first five postnatal days [3H]kainate binding rapidly increased and the maximum density in layer IV was reached at P12. The adult laminar pattern of receptor binding distribution was established by the third postnatal week with the heaviest labeling of infragranular layers. The sharp increase of kainate receptor during the first postnatal week coincides with the critical period for cytoarchitectonic plasticity of the barrels and establishment of functional thalamo-cortical connections in the barrel field.

Progress in the management of Alzheimer's disease

As the population of the United States continues to age, age-related diseases such as Alzheimer's, the most common form of dementia, pose an increasing clinical challenge. The diagnosis of Alzheimer's disease hinges on the evaluation of cognitive function. Management options are expanding and include new cholinesterase inhibitors, cholinergic agonists, antioxidants, monoamine oxidase inhibitors, and estrogen.

Flare during drug withdrawal as a method to support efficacy in rheumatoid arthritis: amiprilose hydrochloride as an example in a double blind, randomized study

OBJECTIVE

To evaluate the use of a randomized, double blind, drug withdrawal design as a means to test the efficacy of longterm therapy with antirheumatic drugs.

METHODS

We evaluated 286 patients with rheumatoid arthritis (RA) treated with amiprilose hydrochloride for 1-3 years, with response, with or without other antirheumatic therapy, in a double blind, 12 week withdrawal study that compared patients randomized to continue amiprilose therapy vs patients randomized to placebo. The primary efficacy variable was preventing a predefined degree of clinical reactivation, or flare; the statistical tests of success were a difference in the proportion of flares and in the mean time to flare.

RESULTS

Thirty percent of patients taking amiprilose and 43% of placebo patients experienced flare (p = 0.026). Patients taking amiprilose had a longer flare-free interval compared to placebo patients (p = 0.027), with the time to reactivation or flare becoming statistically different 73 days after withdrawal.

CONCLUSION

Placebo controlled withdrawal designs are useful as evidence to support the longterm effectiveness of therapy in a proportion of patients with RA.

A first-generation whole genome-radiation hybrid map spanning the mouse genome

We have assembled a first-generation anchor map of the mouse genome using a panel of 94 whole-genome-radiation hybrids (WG-RHs) and 271 sequence-tagged sites (STSs). This is the first genome-wide RH anchor map of a model organism. All of the STSs have been previously localized on the genetic map and are located 8.8 Mb apart on average. This mouse WG-RH panel, known as T31, has an average retention frequency of 27.6% and an estimated potential resolution of 145 kb, making it a powerful resource for efficient large-scale expressed sequence tag mapping. [All of the mapping data for the maps presented here have been deposited at the Research Genetics, Inc., web site and can be freely accessed and downloaded at http://www.resgen.com/.]

A study of the factors affecting the metabolic clearance of quinine in malaria

OBJECTIVE

To assess the factors that contribute to impaired quinine clearance in acute falciparum malaria.

PATIENTS

Sixteen adult Thai patients with severe or moderately severe falciparum malaria were studied, and 12 were re-studied during convalescence.

METHODS

The clearance of quinine, dihydroquinine (an impurity comprising up to 10% of commercial quinine formulations), antipyrine (a measure of hepatic mixed-function oxidase activity), indocyanine green (ICG) (a measure of liver blood flow), and iothalamate (a measure of glomerular filtration rate) were measured simultaneously, and the relationship of these values to the biotransformation of quinine to the active metabolite 3-hydroxyquinine was assessed.

RESULTS

During acute malaria infection, the systemic clearance of quinine, antipyrine and ICG and the biotransformation of quinine to 3-hydroxyquinine were all reduced significantly when compared with values during convalescence. Iothalamate clearance was not affected significantly and did not correlate with the clearance of any of the other compounds. The clearance of total and free quinine correlated significantly with antipyrine clearance (rs = 0.70, P = 0.005 and rs = 0.67, P = 0.013, respectively), but not with ICG clearance (rs = 0.39 and 0.43 respectively, P > 0.15). In a multiple regression model, antipyrine clearance and plasma protein binding accounted for 71% of the variance in total quinine clearance in acute malaria. The pharmacokinetic properties of dihydroquinine were generally similar to those of quinine, although dihydroquinine clearance was less affected by acute malaria. The mean ratio of quinine to 3-hydroxyquinine area under the plasma concentration-time curve (AUC) values in acute malaria was 12.03 compared with 6.92 during convalescence P = 0.01. The mean plasma protein binding of 3-hydroxyquinine was 46%, which was significantly lower than that of quinine (90.5%) or dihydroquinine (90.5%).

CONCLUSION

The reduction in quinine clearance in acute malaria results predominantly from a disease-induced dysfunction in hepatic mixed-function oxidase activity (principally CYP 3A) which impairs the conversion of quinine to its major metabolite, 3-hydroxyquinine. The metabolite contributes approximately 5% of the antimalarial activity of the parent compound in malaria, but up to 10% during convalescence.

Safety of repeated intermittent courses of aerosolized recombinant human deoxyribonuclease in patients with cystic fibrosis

OBJECTIVES

To determine the effect of repeated doses of aerosolized recombinant human deoxyribonuclease (rhDNase) on the development of anti-rhDNase antibodies, acute allergic reactions, and pulmonary function in patients with cystic fibrosis.

DESIGN

A multicenter, open-label study in which 184 patients received 10 mg aerosolized rhDNase twice a day for 14 days followed by a 14-day washout period for a total of 6 treatment cycles. Serial determinations of anti-rhDNase antibodies and pulmonary functions were performed.

RESULTS

Detectable anti-rhDNase antibodies developed in 16 (8.7%) patients. These patients had no changes in their symptoms from the time they entered the trial. Antibodies detected were all of the IgG isotype. Increases in both forced expired volume in 1 second and forced vital capacity were noted from the beginning to the end of each cycle of treatment returning to baseline during the off-treatment period of each cycle. Seropositivity to rhDNase was not associated with allergic reactions and had no relationship on improvement in pulmonary function.

CONCLUSIONS

Development of anti-rhDNase antibodies occurred in a small number of patients and was not associated with side effects. Intermittent administration of rhDNase for 24 weeks to patients with cystic fibrosis was well tolerated and was not associated with anaphylaxis in any patient. Pulmonary function improved significantly during the 14-day cycles while rhDNase was administered and returned to baseline when rhDNase was discontinued.

Sterile abscess formation following plague vaccination

As part of the immunisation programme of servicemen on OP Granby, deployed in the Gulf, plague vaccine was recommended as a prophylaxis. Out of a total of 524 vaccinations at our location, one sterile abscess formation was noted. The case report is described.

Immunologic and autoradiographic localisation of the Na+, K(+)-ATPase in articular cartilage: upregulation in response to changes in extracellular Na+ concentration

The maintenance of a relatively low intracellular Na+:K+ ratio is essential for the functioning of a wide range of cellular processes, and is achieved principally by the activity of the membrane-bound Na+, K(+)-ATPase. Chondrocytes, the cells of articular cartilage, exist in an ionic environment where the free extracellular [Na+] is higher (250-400 mM) than that of most other tissues (approximately 140 mM) owing to the fixed negative charges on glycosaminoglycans in the extracellular matrix. This can increase further during static joint loading when fluid expression occurs. To determine aspects of how chondrocytes regulate their ionic composition, in this study, the in situ distribution, pattern of isoform expression and density of the Na+, K(+)-ATPase within cartilage has been investigated. The density of the Na+, K(+)-ATPase was found to be high in the mid-zone, but lower in the surface and deep zones. Immunofluorescence microscopy using monoclonal antibodies to the catalytic alpha subunits of the Na+, K(+)-ATPase revealed the expression of isoforms alpha 1 and alpha 3. Alterations to the extracellular [Na+] (from 80-220 mM, or 120-220 mM) significantly elevated Na+, K(+)-ATPase density of in situ chondrocytes. The results indicate that the Na+, K(+)-ATPase is abundantly expressed in articular chondrocytes and its density is sensitive to the extracellular [Na+]. The expression of the alpha 3 isoform is surprising for a non-neuronal cell, and may indicate a physiological adaptation to the unusually high extracellular [Na+] to which chondrocytes are exposed in the extracellular matrix of cartilage.

A comparison of peak sputum tobramycin concentration in patients with cystic fibrosis using jet and ultrasonic nebulizer systems. Aerosolized Tobramycin Study Group

STUDY OBJECTIVE

To determine whether adequate concentrations of a new formulation of tobramycin could be delivered to the lower respiratory tract of patients with cystic fibrosis (CF) using a jet nebulizer delivery system.

DESIGN

A multicenter, open-label, randomized, crossover study.

SETTING

Ten tertiary care, university-affiliated, teaching hospitals in the United States.

PATIENTS AND CONTROL SUBJECTS

Sixty-eight patients recruited from 10 CF Foundation centers and who were at least 8 years of age, had a diagnosis of CF, and expectorated daily sputum. No control subjects enrolled.

INTERVENTIONS

Each patient received one administration of aerosolized tobramycin from each of the three nebulizer systems in random order. Each administration was separated by a minimum of 48 h. The two jet nebulizer systems tested were the Sidestream (Medic-Aid; Sussex, UK), and the Pari LC (Pari Respiratory Equipment; Richmond, Va), with a DeVilbiss Pulmoaide compressor (DeVilbiss Health Care; Somerset, Pa), both administering 300 mg tobramycin in 5 mL of 1/4 normal saline solution (NS). Patients were also administered 600 mg tobramycin in 30 mL of 1/2 NS with the UltraNeb 99/100 (DeVilbiss).

MEASUREMENTS

Sputum and serum tobramycin concentration and pulmonary function were monitored. An adequate peak sputum tobramycin concentration was defined as > 128 microg/g sputum at any of three time points (10, 60, or 120 min) after completion of treatments.

RESULTS

The peak tobramycin concentrations in expectorated sputum were 687+/-663 microg/g (mean+/-SD) with the Pari LC and 489+/-402 microg/g with the Sidestream. Adequate peak sputum tobramycin concentration was achieved in 93% of the patients with the Sidestream, and in 87% of the patients with the Pari LC. Peak sputum concentrations were found to be substantially higher when patients received tobramycin administered with the UltraNeb 99/100, 1,498+/-1,331 microg/g with 30% of patients having levels exceeding 2,000 microg/g. Serum tobramycin concentrations were < or = 4 microg/mL for all patients following administration with each nebulizer.

CONCLUSIONS

Adequately high sputum tobramycin concentrations were documented in sputum in > 85% of patients following the administration of 300 mg/5 mL formulation of tobramycin aerosolized by the two jet nebulizer delivery systems, Sidestream and Pari LC. The single tobramycin administration delivered by these two systems is well-tolerated.

Xanthogranulomatous pyelonephritis--a rare case of fistula between colon and kidney

We report the case of a 63 year old lady with xanthogranulomatous pyelonephritis. The treatment of choice is nephrectomy. At operation a fistula between large bowel and kidney was found requiring bowel resection. This is a rare complication of xanthogranulomatous pyelonephritis.

The role of T cells in the regulation of B cell tolerance

The study of conventional models of B cell tolerance has suggested that self-tolerance is imposed on B cells at an early stage in their development due to a peculiar sensitivity of immature B cells to tolerance induction. While this concept accounts for some aspects of central B cell tolerance, it is inconsistent with recent reports of tolerance induction in mature splenic B cells from immunoglobulin transgenic mice. We present an alternative model, the hierarchical model (Aust. N. Z. J. Med. 25, 761-767, 1995), in which regulation of naive B cell reactivity is a function of antigen signal strength and availability of T cell help, but is independent of B cell maturation stage. In turn, the development of tolerance or memory in the T cell compartment is dependent on a combination of antigen-MHC recognition by T cells and antigen-nonspecific signalling by antigen-presenting cells. Using a transgenic model of T-B collaboration, we have shown that both immature and mature self-reactive B cells can be rescued and induced to secrete auto-antibody if the B cell determinant is linked to a carrier protein bearing a foreign T cell determinant.

Haemophilus influenzae pili are composite structures assembled via the HifB chaperone

Haemophilus influenzae is a Gram-negative bacterium that represents a common cause of human disease. Disease due to this organism begins with colonization of the upper respiratory mucosa, a process facilitated by adhesive fibers called pili. In the present study, we investigated the structure and assembly of H. influenzae pili. Examination of pili by electron microscopy using quick-freeze, deep-etch and immunogold techniques revealed the presence of two distinct subassemblies, including a flexible two-stranded helical rod comprised of HifA and a short, thin, distal tip structure containing HifD. Genetic and biochemical studies demonstrated that the biogenesis of H. influenzae pili is dependent on a periplasmic chaperone called HifB, which belongs to the PapD family of immunoglobulin-like chaperones. HifB bound directly to HifA and HifD, forming HifB-HifA and HifB-HifD complexes, which were purified from periplasmic extracts by ion-exchange chromatography. Continued investigation of the biogenesis of H. influenzae pili should provide general insights into organelle development and may suggest novel strategies for disease prevention.

T-cell alpha beta + and gamma delta + deficient mice display abnormal but distinct phenotypes toward a natural, widespread infection of the intestinal epithelium

Vertebrate immune systems contain T cells bearing either alpha beta or gamma delta T-cell antigen receptors (TCRs). alpha beta T cells perform all well-characterized T-cell effector functions, while the biological functions of gamma delta + cells remain unclear. Of particular interest is the role of gamma delta + cells during epithelial infections, since gamma delta + cells are commonly abundant within epithelia. Eimeria spp. are intracellular protozoa that infect epithelia of most vertebrates, causing coccidiosis. This study shows that in response to Eimeria vermiformis, mice lacking alpha beta T cells display defects in protective immunity, while mice lacking gamma delta + cells display exaggerated intestinal damage, apparently due to a failure to regulate the consequences of the alpha beta T cell response. An immuno-downregulatory role during infection, and during autoimmune disease, may be a general one for gamma delta + cells.

Gamma delta T cell help of B cells is induced by repeated parasitic infection, in the absence of other T cells

BACKGROUND

gamma delta T cells, like alpha beta T cells, are components of all well-studied vertebrate immune systems. Yet, the contribution of gamma delta T cells to immune responses is poorly characterized. In particular, it has not been resolved whether gamma delta cells, independent of any other T cells, can help B cells produce immunoglobulin and form germinal centers, anatomical foci of specialized T cell-B cell collaboration.

RESULTS

TCR beta-/- mice, which lack all T cells except gamma delta T cells, routinely displayed higher levels of antibody than fully T cell-deficient mice. Repeated parasitic infection of TCR beta-/- mice, but not of T cell-deficient mice, increased antibody levels and induced germinal centers that contained B cells and monoclonal gamma delta cells in close juxtaposition. However, antibody specificities were more commonly against self than against the challenging pathogen. gamma delta T cell-B cell help was not induced by repeated inoculation of TCR beta-/- mice with mycobacterial antigens.

CONCLUSIONS

In the absence of any other T cells, gamma delta T cell-B cell collaboration can be significantly enhanced by repeated infection. However, the lack of obvious enrichment for antibodies against the challenging pathogen distinguishes gamma delta T cell help from alpha beta T cell help induced under analogous circumstances. The increased production of generalized antibodies may be particularly relevant to the development of autoimmunity, which commonly occurs in patients suffering from alpha beta T cell deficiencies, such as AIDS.

Genetic characterization of trimethoprim resistance in Haemophilus influenzae

We previously demonstrated that trimethoprim (Tmp) resistance in Haemophilus influenzae is mediated by chromosomally encoded dihydrofolate reductase (DHFR) with a modified primary structure and distinct kinetic properties. To gain insight into the relationship of the DHFR structure and the level of Tmp resistance that it confers on the host bacterium, we cloned and characterized the folH genes of one Tmp-susceptible and two Tmp-resistant H. influenzae strains. Differences were observed between Tmp-susceptible and Tmp-resistant isolates both in the promoter region and in the coding sequences. The effect of differences between H. influenzae folH genes on Tmp susceptibility was investigated in Escherichia coli. Various folH gene hybrids were constructed, and their influence on Tmp susceptibility was determined. Resistance in E. coli mediated by folH from H. influenzae strain R1047 was associated with alterations in the promoter and the central part of folH. In contrast, the E. coli Tmp resistance phenotype associated with the folH gene of H. influenzae R1042 was characterized by alterations in one or more of three amino acid residues at the C-terminal part of the protein. These data indicate that Tmp resistance is not only related to alterations in the promoter region of the folH gene and the Tmp binding domains at the N-terminal and central part of DHFR. Alterations in the C-terminal part may also cause Tmp resistance, probably as a result of a change in secondary structure and the subsequent loss of Tmp binding affinity.

Efficient induction of persistent and prenatal parvovirus infection in rats

Parvoviruses are prevalent and disruptive infectious agents of laboratory rats. Risks to rat-based research from infection are increased by the persistence of virus in immune rats and by prenatal transmission of infection. The mechanisms leading to viral persistence and prenatal infection are poorly understood and have been difficult to study for lack of reliable and humane induction methods. We report here protocols for inducing persistent and prenatal infection without causing clinical disease using the UMass strain of rat virus (RV), a common rat parvovirus. Infant rats inoculated by the oronasal route at 6 days of age had greater than 90% prevalence of persistent infection. RV-UMass also induced intrauterine infection in pregnant rats inoculated by the oronasal route. Inoculation of dams at gestation day 9 frequently caused severe disease in the fetuses whereas inoculation at gestation day 12 caused primarily asymptomatic fetal infection that persisted post partum RV-UMass infection facilitates study of parvoviralhost interactions that are relevant to laboratory rats and which also may improve understanding of persistent and prenatal human parvovirus infection.

Rodent parvovirus infections

Parvoviruses are among the most common infectious agents of laboratory rodents and major impediments to rodent-based research. The original prototypic rodent parvoviruses-minute virus of mice, rat virus, and H-1 virus-have recently been joined by biologically and antigenically distinct parvoviruses in mice, rats, and hamsters. Recognition of the increased diversity of rodent parvoviruses presents new challenges for determining the impact of parvovirus infection on research and for detecting, preventing, and eliminating infection. This review summarizes current knowledge about rodent parvoviruses and parvovirus infections, highlighting recent research on newly isolated virus strains.

Late onset haemorrhagic disease in premature infants who received intravenous vitamin K1

The clinical details are reported of two premature infants who developed late onset haemorrhagic disease after receiving their initial doses of vitamin K1 prophylaxis intravenously. Both reported infants had received two doses of intravenous vitamin K1, 0.1 mg, in the 1st week of life, and a further oral dose, 1.0 mg, at 4 weeks. Bleeding due to vitamin K deficiency occurred on days 74 and 84, respectively. Vitamin K deficiency bleeding is rare in low birthweight infants, probably because it has been routine practice to give such infants intramuscular vitamin K1. One of the reported infants had cytomegalovirus hepatitis, the other did not have liver disease. These findings could be explained if intramuscular vitamin K1 were to have a longer duration of effect than intravenous vitamin K1. This may be because intramuscular vitamin K1 acts as a depot preparation. The findings suggest that intravenous vitamin K1 is less effective than intramuscular for long-term prophylaxis against late onset haemorrhagic disease. Intravenous vitamin K1 should not be used for long-term prophylaxis in the prevention of late onset haemorrhagic disease.

Growth characteristics and protein profiles of prototype and wild-type rat coronavirus isolates grown in a cloned subline of mouse fibroblasts (L2p.176 cells)

Rat coronaviruses (RCVs) infect laboratory rats and confound biomedical research results. In vitro systems developed so far have limited the growth in knowledge about RCVs by not permitting generation of plaque-cloned virus stocks, reliable isolation of RCVs from rat tissues, or growth of high titered stocks of all isolates. Due to the fact that less than 20% of L2(Percy) cells were becoming infected, sublines were produced and selected for maximal growth of RCVs. Screening of 238 cell sublines yielded L2p.176 cells which were highly susceptible to all RCVs tested; however, susceptibility declined after 30 passages in vitro. Low-passaged L2p.176 cells were used to isolate virus from natural outbreaks and to propagate individual RCV plaques into high titered stocks. Proteins from six RCV isolates were immunoblotted using polyclonal rat and mouse antibodies to sialodacryoadenitis virus and polyclonal monospecific rabbit and goat antibodies against the peplomer (S) and nucleocapsid (N) proteins of mouse hepatitis virus (MHV). Proteins of two prototype, one Japanese and three wild type RCVs were examined and found to be similar to those of MHV, although the exact sizes and ratios of protein forms were unique for most RCV isolates. This study reports the development of a continuous cell line which reliably supports RCVs opening an opportunity for further in vivo studies of the biology of these agents. As a first step in the characterization of RCVs, we have shown that RCV proteins are very similar to those of MHV.

Mouse parvovirus infection potentiates rejection of tumor allografts and modulates T cell effector functions

Lymphocytotropic mouse parvoviruses can perturb immune responses. For example the recently identified mouse parvovirus designated MPV-1 persistently infects lymphoid tissues and interferes with the ability of cloned T cells to proliferate. As a consequence of these findings the present studies were undertaken to characterize further the immunomodulatory effects of MPV-1 on T cell-mediated immune responses in vivo and in vitro. To evaluate the effect of MPV-1 on CD8+ T cell-mediated responses sarcoma I (SaI) cells, devoid of class II major histocompatibility (MHC) antigens, were administered to MPV-1-infected adult BALB/c mice. MPV-1 infection accelerated tumor allograft rejection. Immunofluorescence staining and in situ hybridization studies of tumors suggested that direct infection of the tumor cells was not responsible for accelerated rejection. Furthermore, compared with uninfected mice, T cells from infected mice that had rejected SaI tumors had a diminished cytolytic capacity. Taken together these results suggest that MPV-1 may induce "bystander help." To examine the in vivo effect of MPV-1 on CD4+ T cell mediated responses adult mice were primed with ovalbumin (OVA) and infected with MPV-1. Spleen and popliteal lymph node cells from OVA-primed mice 3 or 7 days after MPV-1 inoculation had reduced proliferation responses, whereas the proliferative capacity of mesenteric lymph node cells from these mice was increased. Similarly, MPV-1 reduced cytokine-induced proliferation of allospecific CD8+ cloned L3 T cells and OVA-reactive CD4+ T cells without effecting cell viability. Since parvoviruses are widespread among laboratory rodents, these findings emphasize the importance of identifying and excluding parvovirus infections in mice used for transplantation studies and in cultures of mouse T lymphocytes.

The development of topographically-aligned maps of visual and auditory space in the superior colliculus

The role of the superior colliculus in attending and orienting to sensory stimuli is facilitated by the presence within this midbrain nucleus of superimposed maps of different sensory modalities. We have studied the steps involved in the development of topographically-aligned maps of visual and auditory space in the ferret superior colliculus. Injections of fluorescent beads into the superficial layers showed that the projection from the contralateral retina displays topographic order on the day of birth (PO). Recordings made from these layers at the time of eye opening, approximately 1 month later, revealed the presence of an adult-like map of visual space. In contrast, the auditory space map in the deeper layers emerged gradually over a much longer period of postnatal life. In adult ferrets in which one eye had been deviated laterally just before eye opening, the auditory spatial tuning of single units recorded in the contralateral superior colliculus was shifted by a corresponding amount, so that the registration of the visual and auditory maps was maintained. Chronic application of the NMDA-receptor antagonist MK801 disrupted the normal development of the auditory space map, but had no effect on the visual map in either juvenile or adult animals, or on the auditory map once it had matured. These findings indicate that visual cues may play an instructive role, possibly via a Hebbian mechanism of synaptic plasticity, in the development of appropriately tuned auditory responses, thereby ensuring that the neural representations of both modalities share the same coordinates. Changes observed in the auditory representation following partial lesions of the superficial layers at PO suggest that these layers may provide the source of the visual signals responsible for experience-induced plasticity in auditory spatial tuning.

Extensive areas of aneuploidy are present in the respiratory epithelium of lung cancer patients

According to the field cancerisation theory the entire upper aerodigestive tract has been mutagenised, thereby placing the affected individual at risk for the development of one or more cancers. To investigate this concept we studied the respiratory epithelium in lungs bearing cancer, including bronchi, bronchioles and alveoli. After identifying preneoplastic and preinvasive lesions by light microscopy, we determined the DNA content of their nuclei in Feulgen-stained sections using a high-performance digitised image analyser. Archival material from 35 resected cases of non-small-cell lung cancer (NSCLC) was selected, including 16 central tumours (mainly squamous cell carcinomas) and 19 peripheral tumours (mainly adenocarcinomas) and five resected cases of metastatic tumour from extrathoracic primary sites. Of the NSCLCs, 31/35 (89%) were aneuploid, as were 60% of the metastases from extrathoracic sites. Multiple, focal areas of preneoplasia or preinvasive carcinoma were present in the selected cases. The lesions ranged in severity from hyperplasia through metaplasia and dysplasia to carcinoma in situ. Aneuploid preinvasive lesions were not noted in association with the four diploid tumours but were present only when the accompanying NSCLC was aneuploid. With both central and peripheral tumours, aneuploid preneoplastic lesions were more frequent in the peripheral parts of the lung (bronchioles or alveoli) than in the central bronchi. Both the degree and incidence of aneuploidy increased with progressive severity of morphological change. Aneuploidy was not found in preinvasive lesions accompanying the five metastatic cases. Our findings provide strong support for the concept of field cancerisation.

A virulent nonencapsulated Haemophilus influenzae

Nontypeable Haemophilus influenzae strain INT1 was isolated from the blood of a young child with clinical signs of meningitis following acute otitis media. No immunologic or anatomic predisposition of this child for invasive bacterial infection with an unusual organism was documented. Sensitive ELISA proved the absence of intra- or extracellular capsular polysaccharide production by INT1 and Southern blot analysis confirmed the lack of an intact capsulation (cap) gene locus within the chromosome. Nevertheless, INT1 established bacteremia and meningitis in infant and weanling rat models of invasive H. influenzae infection. High-molecular-weight DNA isolated from INT1 was shown to confer an invasive phenotype on transformation of a nonencapsulated, avirulent laboratory strain of H. influenzae. Together these findings imply the presence of one or more as-yet-undiscovered, noncapsular virulence factors of H. influenzae that are capable of mediating invasive disease and resistance to immunologic clearance.

Serologic responses of dogs naturally exposed to or vaccinated against Borrelia burgdorferi infection

OBJECTIVE

To characterize the serologic responses of dogs naturally exposed to or vaccinated against Borrelia burgdorferi and to assess responses at intervals after antibiotic treatment.

DESIGN

Prospective, controlled clinical trial.

ANIMALS

19 dogs of various breeds and ages with narrowly defined clinical criteria of limb/joint borreliosis and 10 control dogs of equivalent age were used to determine serologic responses following natural exposure to the organism. Eight seronegative dogs were used to determine serologic responses following vaccination.

PROCEDURE

Serologic responses to B burgdorferi and recombinant outer surface protein (Osp)A, flagellin, and P39 were assessed by means of ELISA and western immunoblot. Passive protective activity was assessed by use of a mouse protection assay.

RESULTS

Naturally exposed dogs were seropositive, but had variable ELISA titers and immunoblot profiles. Immunoblot analysis did reveal consistent reactions to flagellin, P39, and a 22 kd protein, but not to OspA. Antibody responses did not change appreciably up to 13 weeks after antibiotic treatment. Vaccinated dogs had strong reactions to OspA and OspB, but not to P39.

CLINICAL IMPLICATIONS

Dogs with clinical borreliosis are seropositive and remain seropositive after antibiotic treatment, emphasizing that serologic testing is not a useful means of measuring clinical response. Serologic responses of infected dogs can be discriminated from those of vaccinated dogs by means of immunoblot analysis, and recombinant P39 is a potentially useful antigen for that purpose.

Food shopping practices and family health

"The way in which a family selects, obtains and stores food has a major impact on diet. This includes who in the family makes decisions about food and how, who does the shopping and where, whether they stick to a pre-determined plan or buy whatever looks good at the time, and how much influence the shopper's knowledge of the health effects of diet has on shopping practices. Ways in which shopping practices could be changed - with a high likelihood of compliance over the long term - to improve the family's diet were considered as an exercise in medical education."

A nonlethal rat parvovirus infection suppresses rat T lymphocyte effector functions

Inoculation of the UMass strain of rat virus (RV-UMass) into adult immunocompetent rats results in a prolonged subclinical infection that is resolved in 4 to 8 wk. Co-labeling studies, using in situ hybridization (ISH) and immunohistochemistry (IHC), confirmed that RV-UMass was lymphocytotropic and capable of infecting CD4+ and CD8+ T cells as well as B cells. ISH studies also revealed that virus replication was restricted in unstimulated cells but was productive in concanavalin A-stimulated lymphocytes. A corollary of productive infection of lymphocytes was the suppression of lymphocyte functions. Although RV-UMass did not appear to induce phenotypic changes during the course of infection, cells from infected rats had diminished proliferation and cytolytic responses. Both peripheral and mesenteric lymph node cells exhibited only partial recovery of their proliferative and cytolytic capacities one month after infection. Furthermore, RV-UMass-infected tissue culture maintained alloreactive CD4+ T cells in vitro, and a nonlethal infection of this T cell line inhibited Ag- and IL-2-induced proliferation. Because parvoviruses are widespread among laboratory rodents, these findings emphasize the importance of identifying and excluding parvovirus infection in rodents and in cultures of rat T lymphocytes.

A nonlethal rat parvovirus infection suppresses rat T lymphocyte effector functions

Inoculation of the UMass strain of rat virus (RV-UMass) into adult immunocompetent rats results in a prolonged subclinical infection that is resolved in 4 to 8 wk. Co-labeling studies, using in situ hybridization (ISH) and immunohistochemistry (IHC), confirmed that RV-UMass was lymphocytotropic and capable of infecting CD4+ and CD8+ T cells as well as B cells. ISH studies also revealed that virus replication was restricted in unstimulated cells but was productive in concanavalin A-stimulated lymphocytes. A corollary of productive infection of lymphocytes was the suppression of lymphocyte functions. Although RV-UMass did not appear to induce phenotypic changes during the course of infection, cells from infected rats had diminished proliferation and cytolytic responses. Both peripheral and mesenteric lymph node cells exhibited only partial recovery of their proliferative and cytolytic capacities one month after infection. Furthermore, RV-UMass-infected tissue culture maintained alloreactive CD4+ T cells in vitro, and a nonlethal infection of this T cell line inhibited Ag- and IL-2-induced proliferation. Because parvoviruses are widespread among laboratory rodents, these findings emphasize the importance of identifying and excluding parvovirus infection in rodents and in cultures of rat T lymphocytes.

Enzyme-linked immunosorbent assay for detection of antibody to lymphocytic choriomeningitis virus in mouse sera, with recombinant nucleoprotein as antigen

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of antibody to lymphocytic choriomeningitis virus (LCMV) in mouse sera. This assay is based on recombinant LCMV nucleoprotein generated in a baculovirus system. Sera from experimentally and naturally infected as well as noninfected mice were tested, and the results were compared with those obtained from an established immunofluorescence assay (IFA) that uses infected cells as antigen. An excellent correlation was found; the ELISA specificity and sensitivity were calculated to be 100 and 95% respectively. Unlike the IFA, this ELISA does not require the handling of infective virus. It eliminates the need to work with a zoonotic agent in the laboratory while allowing effective screening of laboratory mouse populations for LCMV antibody.

Manufacture and release characteristics of Elvax polymers containing glutamate receptor antagonists

Implantable sustained-release polymers offer an alternative to osmotic minipumps for the local delivery of drugs to specific brain areas. Here we describe the production of Elvax polymers containing a range of glutamate receptor antagonists and the quantitative characterization of their release properties. Sections of Elvax (200 or 400 microns), prepared by a dimethyl sulphoxide-based method, containing the NMDA antagonist MK-801 or the non-NMDA antagonist CNQX exhibited similar release profiles: an initial 2-week burst followed by a slow decline in release rate over the next 6 weeks. Differences in slice preparation method and thickness or drug concentration and solubility all led to alterations in the level of drug release, but not the overall exponential nature of the release curve. Elvax sections prepared by an aqueous method containing the NMDA antagonists CPP or APV displayed more constant but much lower levels of release than those from the dimethyl sulphoxide-based method. The in vitro release characteristics were compared with in vivo release of MK-801 and the close correspondence observed indicates that the in vitro release data is an accurate predictor of the drug release behaviour of implanted Elvax slices.

Mechanism of amikacin resistance in Pseudomonas aeruginosa isolates from patients with cystic fibrosis

We studied 27 amikacin-resistant isolates of Pseudomonas aeruginosa from patients with cystic fibrosis to determine the mechanism of antibiotic resistance. The absence of aminoglycoside-modifying enzymes (AMEs) in these isolates was inferred from the failure of DNA probes for 16 candidate AMEs to hybridize with DNA harvested from these isolates and, in addition, the uniform reduction in susceptibility to a panel of aminoglycosides. In eight of the 27 isolates that were resistant to amikacin at high levels (minimum inhibitory concentration > or = 250 micrograms/ml), plasmids were not detected. The ribosomes of these isolates were sensitive to amikacin in studies of protein synthesis by cell "ghosts." These data suggest that impermeability is the mechanism of amikacin resistance in isolates of P. aeruginosa from patients with cystic fibrosis. Recognition of this mode of resistance may be difficult, as some isolates appeared to be borderline susceptible when tested against aminoglycosides other than amikacin, or had zone diameters that overlapped those obtained with amikacin-susceptible isolates.

Persistent rat virus infection in juvenile athymic rats and its modulation by immune serum

In contrast to euthymic juvenile rats, which develop acute, self-limiting infection with rat virus (RV), RV infection of juvenile athymic rats was persistent for up to 12 weeks as demonstrated by recovery of infective virus, transmission to cagemates, and detection of viral DNA in the lungs. Administration of RV antiserum at the time of virus inoculation prevented persistent infection in five of six rats. Among rats given RV antiserum 1 week after virus, the interval at which euthymic rats begin to seroconvert, RV was not detected 1 week later but was recovered from four of six rats 3 weeks later. Results of these studies confirm that T-cell deficiency facilitates persistent RV infection and indicate that antibody provides significant protection from persistent infection only if it is present at the time of virus inoculation. The results support the concept that factors which prevent persistent infection in euthymic rats act early after virus inoculation and may include cellular immunity.

Attentional strategy use by experienced distance runners: physiological and psychological effects

The purpose of this investigation was twofold: (a) to compare most and least economical runners on use of attentional strategies and (b) to determine whether the least economical runners within the subject sample could improve running economy (RE) with the use of an active associative (relaxation) attentional strategy. Subjects (N = 36) completed an initial assessment of attentional style and RE; then the 12 least economical runners ran in each of three laboratory sessions using control, passive associative, and active associative attentional strategies. Results showed that the most economical and least economical runners did not differ in associative style use. The most economical runners, however, reported less dissociation use and more use of relaxation than did the least economical runners. No significant physiological or psychological changes were associated with any of the three attentional strategy conditions. The findings are related to possible differences in how most and least economical runners use associative strategies.