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.

Characterization of mouse parvovirus infection by in situ hybridization

Infection of young adult BALB/cByJ mice with mouse parvovirus-1, a newly recognized, lymphocytotropic, nonpathogenic parvovirus, was examined by in situ hybridization. Virus appeared to enter through the small intestine and was disseminated to the liver and lymphoid tissues. Strand-specific probes detected virion DNA in a consistently larger number of cells than replicative forms of viral DNA and/or viral mRNA. The number of signal-positive cells in the intestinal mucosa, lymph nodes, spleen, and thymus increased through day 10 after oral inoculation but decreased after seroconversion. Positive cells were still detected, however, in peripheral lymphoid tissues of mice examined at 9 weeks postinoculation. The results underscore the need to assess potential effects of persistent mouse parvovirus-1 infection on immune function in mice.

Pez: a novel human cDNA encoding protein tyrosine phosphatase- and ezrin-like domains

We have isolated cDNAs from normal human breast tissue and breast tumour cells that encode a protein (pez) with features of a novel non-receptor tyrosine phosphatase possessing N-terminal sequence homology to the ezrin-band 4.1-merlin-radixin protein family. Northern blot analysis indicates that pez is expressed in a variety of human tissues including kidney, skeletal muscle, lung and placenta. Fluorescence in situ hybridization has mapped pez to chromosome 1 region q32.2-41. Sequence identity to a characterized polymorphic marker confirms this localization.

NMDA-receptor antagonists disrupt the formation of the auditory space map in the mammalian superior colliculus

In the ferret (Mustela putorius) the map of auditory space in the deeper layers of the superior colliculus (SC) matures over a period of several postnatal weeks, a process known to be guided by both visual and auditory experience. The auditory responses are initially very broadly tuned, and gradually become more selective for specific sound locations that coincide with the visual receptive fields recorded in the same region of the SC. To investigate the possible involvement of NMDA-type glutamate receptors in the postnatal development of this auditory representation, we have reared ferrets in which 400 microns thick sheets of the slow-release polymer Elvax, containing the NMDA receptor antagonists MK801 or APV, were placed on the dorsal surface of the SC. The Elvax was implanted on postnatal day (P) 25-27, just before the onset of hearing, and removed 5-6 weeks later, just prior to recording from the SC on around P61-70. In vitro measurements with Elvax containing 3H-MK801 revealed that the amount of drug released declined sharply over the first 10 d and then stabilized at a fairly constant rate for the following 5 weeks. These in vitro data were found to parallel the in vivo release of MK801 from implanted Elvax slices. Diffusion of MK801 from the implant was measured and significant levels were found within 800 microns of the SC surface, suggesting that the action of MK801 was restricted to the superficial and intermediate layers of the nucleus. Extracellular recordings were made from visual and auditory units in the SC in response to free-field stimulation. The visual responses of units recorded in the superficial layers appeared to be unaffected by either of the drug treatments, and formed a normal, adult-like map of visual azimuth along the rostrocaudal axis of the SC in all animals. Most of the auditory single-unit responses recorded at this age in normal, unoperated controls were spatially tuned and topographically organized, although the map of sound azimuth was less precise than that in adult ferrets. Data from age-matched control animals that had been reared with drug-free Elvax implants were not statistically different from the unoperated juvenile ferrets. However, in animals reared with APV or MK801 Elvax implants, there was an increase in the relative numbers of auditory units that were ambiguously tuned to two or more locations.(ABSTRACT TRUNCATED AT 400 WORDS)

Aerosol administration of antibiotics

Antibiotics can be aerosolized to the lower respiratory tract of patients with pulmonary infections. With attention to stability of the antibiotic, its ability to be aerosolized, and particle size of the aerosol, rational design of an antibiotic aerosol treatment regimen is possible. The choice of nebulizer for aerosol antibiotic administration depends not only on drug stability under the nebulization conditions, but practical considerations such as ease of use in the home and expense. In general, a greater volume of respirable aerosol is generated by an ultrasonic device in comparison to the jet nebulizers. Of the factors affecting antibiotic delivery to the lower respiratory tract, the patients and their disease are the most important. This patient effect is not directly amenable to medical intervention, but can be controlled through measurement of antibiotic concentrations in respiratory secretions, seeking a target estimated from the best available in vitro data.

Aerosol administration of antibiotics

Aerosol administration of antibiotics is an attractive approach to the treatment of the recurrent respiratory infections experienced by patients suffering from cystic fibrosis (CF). Through aerosol administration, drugs can, theoretically, be delivered directly to the target site of infection, i.e. the lumen of the lower respiratory tract, thus enabling smaller doses to be given. This, in turn, should result in reduced costs and decreased potential for systemic toxicity. The efficacy of aerosol antibiotic therapy is, however, influenced by numerous variables, including the type of nebulizer device used to deliver the aerosol, the drug's physical properties, its concentration in the aerosol and particle size, carrier gas and patient factors. The efficacy of aerosol antibiotics in the treatment of CF is controversial. This appears to be due mainly of problems and inconsistencies with clinical trials. However, various antibiotics, including beta-lactams, polymyxins and aminoglycosides, have demonstrated clinical benefits when administered by inhalation to CF patients.

Macromolecular mechanisms of sputum inhibition of tobramycin activity

Tobramycin, an aminoglycoside antibiotic, is used in the treatment of Pseudomonas aeruginosa infections in cystic fibrosis patients. Tobramycin bioactivity, however, is antagonized by sputum. Glycoproteins (mucins) and high-molecular-weight DNA make up 2 to 3% (P. L. Masson and J. F. Heremans, p. 412-475, In M. J. Dulfano, ed., Sputum: Fundamentals and Clinical Pathology, 1973) and 3 to 10% (W. S. Chernick and G. J. Barbero, Pediatrics 24:739-745, 1959, and R. Picot, I. Das, and L. Reid, Thorax 33:235-242, 1978) of the dry weight of sputum, respectively. tobramycin binds to both mucins and DNA obtained from sputum (R. Ramphal, M. Lhermitte, M. Filliat, and P. Roussel, J. Antimicrob. Chemother. 22:483-490, 1988). In vitro, recombinant human DNase (rhDNase) hydrolyzes high-molecular-weight DNA of > 50 kb within sputum to fragments of 2 to 4 kb. Studying dialyzable tobramycin, we examined drug binding to whole sputum and to "mock sputum," which consisted of porcine gastric mucin and calf thymus DNA. We also studied the effects of rhDNase treatments of sputum, mock sputum, and calf thymus DNA on tobramycin binding. We found that treatments of sputum, mock sputum, and calf thymus DNA with rhDNase did not significantly increase the tobramycin bioactivity within the dialysates; surprisingly, sputum binding of tobramycin was increased by rhDNase. We conclude that rhDNase does not increase the bioactivity of tobramycin in sputum.

Differences in eucaryotic cell binding of Pseudomonas

The lungs of cystic fibrosis (CF) patients are frequently chronically colonized by Pseudomonas aeruginosa. Recently there has been an increase in colonization by another pathogen Pseudomonas cepacia, which can cause a rapid decline in clinical condition or death of the patient. The nature of the factor(s) which predispose CF patients to colonization by one or both of these opportunistic pathogens is unknown. It has been suggested that the genetic defect in CF patients results in an increase in the number of epithelial cell receptors available to P. aeruginosa in the lung, thus rendering CF patients more susceptible to bacterial colonization than non-CF individuals. In this study, we have examined adherence of several strains of P. aeruginosa and P. cepacia to a variety of continuous cell lines, as well as primary cultures of CF and non-CF nasal polyp cells. The results suggested that there may be a decrease in the number of receptors available to both strains of Pseudomonas on cells of canine origin compared to human cells. Both strains appear to use pili as the primary adhesin, but there is also evidence that non-pilus adhesins contribute significantly to eucaryotic cell binding. P. cepacia exhibited microcolony formation on all cell types, which is typical of the localized adherence pattern characteristic of the enteropathogenic Escherichia coli. However, we were unable to demonstrate, with either P. cepacia or P. aeruginosa, a significant increase in adherence to CF compared to non-CF nasal polyp cultures.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of aerosolized recombinant human DNase on exacerbations of respiratory symptoms and on pulmonary function in patients with cystic fibrosis. The Pulmozyme Study Group

BACKGROUND

Respiratory disease in patients with cystic fibrosis is characterized by airway obstruction caused by the accumulation of thick, purulent secretions, which results in recurrent, symptomatic exacerbations. The viscoelasticity of the secretions can be reduced in vitro by recombinant human deoxyribonuclease I (rhDNase), a bioengineered copy of the human enzyme.

METHODS

We performed a randomized, double-blind, placebo-controlled study to determine the effects of once-daily and twice-daily administration of rhDNase on exacerbations of respiratory symptoms requiring parenteral antibiotics and on pulmonary function. A total of 968 adults and children with cystic fibrosis were treated for 24 weeks as outpatients.

RESULTS

One or more exacerbations occurred in 27 percent of the patients given placebo, 22 percent of those treated with rhDNase once daily, and 19 percent of those treated with rhDNase twice daily. As compared with placebo, the administration of rhDNase once daily and twice daily reduced the age-adjusted risk of respiratory exacerbations by 28 percent (P = 0.04) and 37 percent (P < 0.01), respectively. The administration of rhDNase once daily and twice daily improved forced expiratory volume in one second during the study by a mean (+/- SD) of 5.8 +/- 0.7 and 5.6 +/- 0.7 percent, respectively. None of the patients had anaphylaxis. Voice alteration and laryngitis were more frequent in the rhDNase-treated patients than in those receiving placebo but were rarely severe and resolved within 21 days of onset.

CONCLUSIONS

In patients with cystic fibrosis, the administration of rhDNase reduced but did not eliminate exacerbations of respiratory symptoms, resulted in slight improvement in pulmonary function, and was well tolerated.

The role of natural killer cells in resistance to coccidiosis: investigations in a murine model

Natural killer (NK) activity, detected by the lysis of Yac-1 target cells, was examined in splenic and mesenteric lymph node (MLN) cells throughout the course of infection with Eimeria vermiformis in BALB/c and C57B1/6 (B6) mice. These strains are, respectively, relatively resistant and susceptible to primary infections, which render them equally, and completely, resistant to challenge. Resting levels of NK activity were higher in B6 than in BALB/c, and B6 responded earlier in the course of infection than BALB/c, but splenic peak values were higher in BALB/c; the pattern of response in MLN cells was similar in both strains, but the peak was higher in BALB/c. At the time (7 days p.i.) of peak NK response in BALB/c mice there was, depending upon the choice of NK-resistant/lymphokine-activated killer (LAK)-sensitive target cells, either little (P388D1), or no (P815) splenic LAK activity. Challenge of immunized BALB/c mice did not evoke a detectable NK response. Although the higher NK activity in BALB/c mice correlated with greater control of primary infection, depletion of NK activity (demonstrated in splenic cells) in vivo by treatment with anti-asialo GM1 antibodies did not greatly affect the course of infection. Furthermore, this treatment did not augment the exacerbation of infection produced by treatment with anti-interferon-gamma (IFN-gamma) MoAb, indicating that, at least in this system, NK cells are not a fundamentally important source of this controlling cytokine of eimerian infections. The results suggest that NK cells may not greatly influence the outcome of coccidial infections.

Invasive disease caused by Neisseria meningitidis relatively resistant to penicillin in North Carolina

A case of sepsis and meningitis caused by Neisseria meningitidis with relative resistance to penicillin occurred in North Carolina in August 1992. This isolate was relatively resistant due to decreased affinity of its penicillin-binding protein 2 for penicillin. Such isolates have been reported in Spain, elsewhere in Europe, in South Africa, and in Canada, but invasive disease caused by meningococcal isolates relatively resistant to penicillin was not recognized in the United States before a preliminary report of this case in October 1992. The Centers for Disease Control and Prevention recently retrospectively identified 3 additional cases from 1991. A fifth case occurred in Kentucky in 1993. Surveillance studies of penicillin susceptibility of N. meningitidis isolates suggest such meningococci have existed sporadically in the past. Increases in prevalence and magnitude of penicillin resistance among strains of N. meningitidis would require reconsideration of current clinical practice with regard to treatment of meningococcal disease.

Distinct laminar differences in the distribution of excitatory amino acid receptors in adult ferret primary visual cortex

In order to explore the relative contributions of the different ionotropic excitatory amino acid receptor subtypes to signalling in primary visual cortex, we have mapped their distributions in area 17 of adult ferret cerebral cortex by quantitative in vitro autoradiography. D,L-alpha-amino-3-hydroxy-5-methoxy-4-isoxazole propionate (AMPA) and kainate receptors, gating fast, Na(+)-permeable channels, were localized with [3H]dizocilpine maleate ([3H]MK-801). All three radioligands bound to single sites, with KDs of 414 nM [3H]AMPA and [3H]kainate, respectively. Slower-acting N-methyl-D-aspartate receptors, which gate the influx of Ca2+ as well as Na+, were localized with ([3H]AMPA), 78 nM ([3H]kainate) and 16 nM ([3H]MK-801), and each receptor subtype displayed a different laminar distribution pattern within area 17. AMPA receptors were concentrated in superficial layers, with intermediate densities in deep layers and lowest levels in layer IV. Kainate receptor levels were high in layers V and VI and low in all other layers. N-methyl-D-aspartate receptors were more homogeneously distributed than AMPA or kainate receptors, but were expressed at highest levels in layers I and IV and lowest levels in layers V and VI. The binding site densities found in the layers containing most receptors were Bmax = 2812 fmol/mg for [3H]AMPA, Bmax = 626 fmol/mg for [3H]MK-801 maleate and Bmax = 278 fmol/mg for [3H]kainate. Thus, while AMPA receptors were predominant and kainate receptors least abundant in all cortical layers, a complementary relative distribution of excitatory amino acid receptors was apparent, with AMPA receptor density highest in superficial layers, kainate receptor density highest in inferior layers and N-methyl-D-aspartate receptor density highest in the middle granular layer, as well as in layer I. The results indicate that although AMPA receptors are principally involved in excitatory signalling in adult ferret primary visual cortex, kainate receptors in layers V and VI and N-methyl-D-aspartate receptors in layers I and IV may have particularly important roles in mediating synaptic transmission.

Telecommuting: stress and social support

Occupational stress and social support were measured in adults, 15 working as telecommuters, 9 working at home, and 14 working in a company office. Analysis showed telecommuters and office workers perceived more support than those working at home. Telecommuters also reported less stress and a stronger preference for this new work option.

Automated ventilator testing

A new era has arrived for the Biomedical Engineering Department at the Royal Women's Hospital in Melbourne. We have developed a system to qualitatively test for intermittent or unconfirmed faults, associated with Bear Cub ventilators. Where previous testing has been inadequate, computer logging is now used to interface the RT200 Timeter Calibration Analyser (TCA) to obtain a real time display of data, which can be stored and graphed. Using Quick Basic version 4.5, it was possible to establish communication between the TCA and an IBM compatible computer, such that meaningful displays of machine performance were produced. From the parameters measured it has been possible to obtain data on Peak Pressure, Inspiratory to Expiratory ratio (I:E ratio) Peak Flow and Rate. Monitoring is not limited to these parameters, though these were selected for our particular needs. These parameters are plotted in two ways: 1. Compressed average versus time, up to 24 hours on one screen 2. Raw data, 36 minutes displayed on each screen. The compressed data gives an overview which allows easy identification of intermittent faults. The uncompressed data confirms that the averaged signal is a realistic representation of the situation. One of the major benefits of this type of data analysis, is that ventilator performance may be monitored over a long period of time without requiring the presence of a service technician. It also allows individual ventilator performance to be graphically compared to other ventilators.

Reovirus serotype 3 infection in infants with extrahepatic biliary atresia or neonatal hepatitis

Infection with reovirus serotype 3 (reo 3) has been postulated to be associated with extrahepatic biliary atresia (EHBA) in infants, and with neonatal hepatitis (NNH). We have investigated this association by assaying antireo 3 antibodies in sera from infants (aged < 4 months) with EHBA (n = 40), NNH (59), cholestatic liver disease due to other causes (61) and control infants with no liver disease (138). Antireo 3 immunoglobulins (Ig) of the G, A and M classes were measured by enzyme-linked immunosorbent assay. No differences in the prevalence of antireo 3 IgG or IgA were found between any of the four groups. A significantly higher prevalence of positive antireo 3 IgM was found in infants with EHBA (12/40), NNH (12/59) or cholestatic liver disease associated with parenteral nutrition (7/17), alpha-1 antitrypsin deficiency (4/15) or a variety of other causes (15/29) compared with control infants (13/138). These data support an association between reovirus 3 infection and cholestatic liver disease in infants. The nature of this association may differ for EHBA, NNH and cholestatic liver disease due to other causes, and remains to be determined.

Disposition of drugs in cystic fibrosis. VI. In vivo activity of cytochrome P450 isoforms involved in the metabolism of (R)-warfarin (including P450 3A4) is not enhanced in cystic fibrosis

OBJECTIVE

To determine whether the activity of cytochrome P450 isoforms involved in the metabolism of (R)-warfarin is enhanced in cystic fibrosis.

DESIGN

Six adult subjects with cystic fibrosis and six healthy control subjects, matched by age and sex, were administered (R)-warfarin as a single intravenous bolus dose (0.375 mg/kg), and urine and plasma samples were collected for 192 hours. The concentration of (R)-warfarin in plasma and the concentration of (R)-warfarin and its metabolites in urine were determined by HPLC and GC/MS, respectively. Plasma protein binding of (R)-warfarin was measured by ultrafiltration.

RESULTS

The unbound plasma clearance of (R)-warfarin was not significantly (p > 0.05) different between the cystic fibrosis and the control groups (cystic fibrosis, 997 +/- 483 ml/hr/kg; control, 788 +/- 219 ml/hr/kg). The unbound metabolic clearances of (R)-warfarin to its oxidative metabolites--6-hydroxywarfarin, 7-hydroxywarfarin, 8-hydroxywarfarin, and 10-hydroxywarfarin (mediated by P450 3A4)--were also similar (p > 0.05) in the two groups (6-hydroxywarfarin: cystic fibrosis: 124.2 +/- 72.8 ml/hr/kg, control: 99.4 +/- 37.3 ml/hr/kg; 7-hydroxywarfarin: cystic fibrosis: 43.8 +/- 32.2 ml/hr/kg, control: 34.5 +/- 10.6 ml/hr/kg; 8-hydroxywarfarin: cystic fibrosis: 80.4 +/- 85.4 ml/hr/kg, control: 69.5 +/- 39.5 ml/hr/kg; 10-hydroxywarfarin: cystic fibrosis: 4.38 +/- 2.72 ml/hr/kg, control: 16.28 +/- 13.71 ml/hr/kg).

CONCLUSION

The in vivo activity of cytochrome P450 isoforms involved in the metabolism of (R)-warfarin, including P450 3A4, is not enhanced in cystic fibrosis.

Accuracy and cost of antibiotic susceptibility testing of mixed morphotypes of Pseudomonas aeruginosa

Chronic Pseudomonas aeruginosa colonization of the lower respiratory tract of patients with cystic fibrosis frequently results in pulmonary exacerbations requiring treatment with antimicrobial agents. Multiple morphotypes with different antibiotic susceptibilities are often isolated from a single sputum sample. Determination of MICs of antibiotics for each sputum morphotype is used to guide therapy but is time-consuming and expensive. We explored an alternative assay for determining MICs for all P. aeruginosa morphotypes cultured from a homogenized sputum sample. We sought correlations of those MICs with the MIC for the most resistant morphotypes tested separately. The MICs determined for a mixture of morphotypes correctly predicted the highest MICs (+/- one dilution) determined for isolated morphotypes 73.5% of the time. The MIC for the mixed morphotypes correctly predicted susceptibility in 90.4% of samples. In contrast, determination of the MIC for the mixture of morphotypes correctly predicted resistance in only 57.0%. For sputa containing susceptible isolates, testing the mixed culture may provide adequate susceptibility data with significant laboratory time and cost savings. However, for sputa with resistant strains, the traditional method of testing isolated morphotypes should still be used.

Disposition of drugs in cystic fibrosis. VII. Acetylation of sulfamethoxazole in blood cells: in vitro-in vivo correlation and characterization of its kinetics of acetylation in lymphocytes

OBJECTIVE

To determine if acetylation of sulfamethoxazole in blood cells is a surrogate measure of its acetylation in vivo. If it is, to use these cells to determine the mechanism(s) by which acetylation of sulfamethoxazole is enhanced in cystic fibrosis.

METHODS

Single-point sulfamethoxazole acetylation activity in blood cells obtained from patients with cystic fibrosis (n = 6) and control subjects (n = 7) who had previously participated in our in vivo study was determined. The parameters, Vmax and Km, for acetylation of sulfamethoxazole in lysed lymphocytes obtained from patients with cystic fibrosis (n = 6) and control subjects (n = 5) were also determined.

RESULTS

The acetylation activity in cystic fibrosis whole blood, lysed erythrocytes, and lysed peripheral blood mononuclear cells was significantly (p < 0.05) greater than that in cells obtained from control subjects and was highly correlated with acetylation of sulfamethoxazole in vivo (r > 0.80). The apparent Vmax for cystic fibrosis lymphocyte lysate was significantly (p < 0.05) greater than that obtained for control lymphocyte lysate (72.99 +/- 9.07 versus 60.97 +/- 2.26 pmol/mg protein/min), and the apparent Km was significantly (p < 0.05) lower (0.51 +/- 0.07 versus 0.73 +/- 0.06 mmol/L).

CONCLUSION

Blood cells may be used as surrogate markers to elucidate the mechanism(s) by which acetylation of sulfamethoxazole (catalyzed by the monomorphic N-acetyltransferase) is enhanced in subjects with cystic fibrosis. Both activation or activation and induction of the monomorphic N-acetyltransferase should be considered as possible mechanism(s) to explain this phenomenon.

Infectivity, disease patterns, and serologic profiles of reovirus serotypes 1, 2, and 3 in infant and weanling mice

The oronasal median infectious doses of reovirus serotypes 1, 2, and 3 were established in infant and weanling Sencar mice on the basis of disease expression and seroconversion. Infant mice were susceptible to infection with low doses of all three serotypes, whereas weanling mice were comparatively resistant to infection. Uniform transmission of virus to cagemates or mothers of infants did not occur, indicating low contagiousness of all three virus serotypes. The comparative susceptibility of 2-day-old Sencar mice to disease was examined following oronasal inoculation with reovirus 1, 2, or 3. Tissues were collected on days 3, 5, 7, 9, 14, 16, and 21 after inoculation for virus isolation, histologic examination, and serologic analysis. Disease patterns in infant mice were distinctly different among reovirus serotypes. Reovirus 3 induced severe disease, with focal myocarditis, hepatitis, diffuse encephalitis, and generalized lymphoid depletion, whereas reovirus 1 induced a similar pattern, but much milder disease. In contrast, reovirus 2 induced mild transient enteritis without lesions in other organs. Sera from experimentally infected mice were tested in virus serotype-specific enzyme immunoassays. Cross reactivity of antibody among the three virus serotypes was found, but antibody titers were always highest with the homologous antigen. These studies confirm that infant laboratory mice are susceptible to infection with all three serotypes of virus; weanling mice are comparatively resistant to infection and disease; the viruses induce different patterns of disease in infant mice; and infecting virus serotypes can be distinguished serologically by enzyme immunoassay.

Variant responses of mice to Borrelia burgdorferi depending on the site of intradermal inoculation

C3H/He mice inoculated intradermally at one of two sites with Borrelia burgdorferi responded differently to infection. Shoulder-inoculated mice developed spirochetemia, B. burgdorferi-specific antibody, and arthritis earlier than foot-inoculated mice. Lymphocyte populations derived from spleen tissue were elevated in the shoulder- but not the foot-inoculated mice, and those from lymph nodes were increased in both groups. Lymphocytes derived from blood and spleen tissue showed impaired proliferative responses to all mitogens for shoulder-inoculated mice only, whereas proliferation of lymph node cells was not affected, regardless of route. These results demonstrate that the site of initial B. burgdorferi inoculation is an important determinant in the pathogenesis of B. burgdorferi infection.

Pilot investigation of naproxen/methotrexate interaction in patients with juvenile rheumatoid arthritis

OBJECTIVE

To investigate the potential interaction of naproxen and methotrexate (MTX) in children with juvenile rheumatoid arthritis (JRA).

METHODS

Nine children with JRA served as their own control taking their usual doses of MTX (0.22-1.02 mg/kg/week) and naproxen (14.6-18.8 mg/kg/day) separately and in combination.

RESULTS

MTX affected a > or = 30% change in naproxen kinetics in 6/8 patients, while naproxen altered MTX kinetics by > or = 30% in 4/9 patients.

CONCLUSION

MTX can alter nonsteroidal antiinflammatory drug (NSAID) kinetics in children with JRA and NSAID can alter MTX kinetics. NSAID toxicity should be considered when assessing adverse reactions in patients receiving the combination treatment of MTX and NSAID:

Disposition of drugs in cystic fibrosis. IV. Mechanisms for enhanced renal clearance of ticarcillin

To investigate the hypothesis that renal secretion of penicillins is enhanced in cystic fibrosis the maximal tubular secretion rate (Tmax) of ticarcillin and the serum concentration of ticarcillin at half-maximal secretion rate (TC50) were determined in patients with cystic fibrosis (n = 6) and control subjects (n = 6). Each subject received three consecutive constant-rate intravenous infusions of ticarcillin (4, 13, and 70 mg/kg/hr; 2 1/2 hours each) simultaneously with a constant-rate (30 mg/kg/hr) infusion of insulin. Urine samples were collected at 1/2-hour intervals and serum samples at the midpoint of the urine collections. Ticarcillin and inulin concentrations in serum and urine were determined by high-performance liquid chromatographic and a spectrophotometric method, respectively. Ticarcillin serum protein binding was determined by ultrafiltration. Steady-state ticarcillin serum concentrations were achieved at all three infusion rates. The TC50 was significantly lower (p < 0.05) in patients with cystic fibrosis (33.7 +/- 12.2 micrograms/ml) compared with that in control subjects (77.6 +/- 38.4 micrograms/ml). In contrast, the Tmax was similar (cystic fibrosis, 0.25 +/- 0.12 mg/min/kg; control, 0.22 +/- 0.14 mg/min/kg; p > 0.05). These data indicate that renal clearance of penicillins is enhanced in cystic fibrosis because of greater affinity of the renal secretory system for these drugs.

Effect of age on distribution of zidovudine (azidothymidine) into the cerebrospinal fluid of Macaca nemestrina

The brain tissue is an important target for anti-HIV drug therapy. Since the permeability of the blood-brain and blood-cerebrospinal fluid (CSF) barriers may differ between neonates and adults, we have determined the effect of age on the distribution of zidovudine (ZDV or azidothymidine) into the CSF in the macaque (M. nemestrina). Five newborn macaques were administered ZDV (iv bolus, 5 mg/kg) at various ages (2 days to 4 months). Both CSF (cisternal) and venous blood samples were obtained at approximately 60 and 90 min after drug administration. In another series of experiments, adult female macaques received ZDV as either an iv bolus (5 and 10 mg/kg) or an infusion for at least 12 hr. CSF (lumbar) and venous blood samples were obtained at approximately 60 and 90 min after iv bolus and at more than 12 hr after iv infusion. ZDV concentration in the CSF and the plasma samples was determined by high-performance liquid chromatography. The CSF/plasma concentration ratio of ZDV in the newborn and adult macaques, after iv bolus administration, was independent of time. In addition, no significant (P > 0.05) difference was observed in the pooled iv bolus ZDV CSF/plasma concentration ratio between the adult group (0.236 +/- 0.058) and the newborns (0.213 +/- 0.039). Moreover, the ZDV CSF/plasma concentration ratio in the adults and the newborns, after iv bolus administration, was found not to be significantly (P > 0.05) different from the ratio obtained at steady state in the adults (0.224 +/- 0.094). These data indicate that the distribution of ZDV into the CSF in macaque neonates and adults is similar.

Disposition of drugs in cystic fibrosis. V. In vivo CYP2C9 activity as probed by (S)-warfarin is not enhanced in cystic fibrosis

Enhanced metabolism of theophylline in subjects with cystic fibrosis suggests that the activity of certain cytochrome P450 isoforms is affected in subjects with this genetic disease. To determine whether this effect on the P450 enzymes is selective, the in vivo activity of the cytochrome P450 isoform CYP2C9 was determined in adult subjects with cystic fibrosis (n = 6) and in control subjects (n = 8). Subjects were administered (S)-warfarin as a single intravenous bolus dose (0.375 mg/kg), and urine and plasma samples were collected for 96 hours. Plasma (S)-warfarin concentrations were determined by HPLC; urinary concentrations of (S)-warfarin and its metabolites were determined by gas chromatography-mass spectrometry. The total plasma clearance of (S)-warfarin (subjects with cystic fibrosis, 3.6 +/- 0.48 ml/hr/kg; control subjects, 3.82 +/- 0.73 ml/hr/kg), elimination half-life (subjects with cystic fibrosis, 29.5 +/- 4.2 hours; control subjects, 25.9 +/- 5.4 hours); and steady-state volume of distribution (subjects with cystic fibrosis, 153 +/- 18 ml/kg; control subjects, 138 +/- 22 ml/kg) were similar in the two groups (p > 0.05). The metabolic clearance of (S)-warfarin to its major metabolites mediated by CYP2C9, 6-hydroxywarfarin and 7-hydroxywarfarin, was not significantly (p > 0.05) different between the two groups (6-hydroxywarfarin: subjects with cystic fibrosis, 0.33 +/- 0.1 ml/hr/kg; control subjects, 0.41 +/- 0.1 ml/hr/kg; 7-hydroxywarfarin: subjects with cystic fibrosis, 1.34 +/- 0.49 ml/hr/kg; control subjects, 1.8 +/- 0.45 ml/hr/kg). On the basis of these data, we conclude that the in vivo cytochrome P450 activity is selectively affected in persons with cystic fibrosis.

Chronic Lyme borreliosis in the laboratory mouse

C3H/HeJ mice were inoculated intraperitoneally with 10(7) uncloned Borrelia burgdorferi at 4 weeks of age and examined on days 30, 90, 180, and 360. Spirochetes were isolated from multiple tissues at all intervals. Joint and heart disease were present in all mice at 30 days and resolved after 90 days. At 180 and 360 days, some mice had mild recurrent joint and heart disease, and most had peripheral segmental periarteritis. The protein electrophoretic migration of 360-day isolates differed from the original inoculum. The experiment was repeated with C3H/HeN and BALB/cByJ mice inoculated intradermally with 10(4) cloned B. burgdorferi. Characterization of infection and disease at 180 and 360 days were similar to those of the first experiment, but spirochetal proteins of isolates from both intervals displayed no protein variation in electrophoretic mobilities. Spirochetes isolated at 360 days were fully pathogenic in naive mice. Sera from infected mice showed an initial immunoglobulin M response, followed by a sustained immunoglobulin G response, involving IgG1, IgG2a, IgG2b and IgG3, with expanding reactivity against multiple antigens over time. These results indicate that immunocompetent mice sustain persistent infections and develop early acute joint and heart lesions that resolve and then recur intermittently.

Enterotropic coronavirus (mouse hepatitis virus) in mice: influence of host age and strain on infection and disease

The course of enterotropic mouse hepatitis virus (MHV) infection was examined in genetically susceptible (BALB) and resistant (SJL) mice of different ages at inoculation (1, 3, and 12 weeks) and at sequential intervals (1, 2, 3, 5, 10, 20, and 30 days) after oral inoculation with the Y strain of MHV (MHV-Y). Virus was quantified in stomach, upper and lower segments of small intestine, cecum, upper and lower segments of colon, Peyer's patches, mesenteric lymph node, and feces, and tissues were examined microscopically. An infant mouse bioassay was used to quantify virus in all tissues of 3-week-old BALB mice and ascending colons of other mouse groups. MHV-specific serum IgG antibody titers were measured with an enzyme immunoassay, using MHV-S-infected 17 Cl 1 cells as antigen. Lesions were first detectable at 2 days and were most severe in 1-week-old mice and more severe in BALB mice, compared with SJL mice of the same age. Additional BALB mice inoculated at the age of 24 hours developed severe necrotizing enterocolitis, whereas SJL mice inoculated at the age of 24 hours developed lesions equivalent to those in 1-week-old BALB mice. Virus was first detectable at 2 days and virus titers were highest at 2, 3, and 5 days, then diminished on days 10, 20, and 30. Low titers of virus were found in a few mice of different ages and genotypes through day 30. Lesions were most severe and virus titers highest in the ascending colon.(ABSTRACT TRUNCATED AT 250 WORDS)

Trophectoderm microbiopsy in murine blastocysts: comparison of four methods

PURPOSE

This study compares four trophectoderm microbiopsy techniques for removal of blastomeres from murine blastocysts: (1) aspiration, trophectoderm pipetted through the zona; (2) incision, trophectoderm excised with a microrazor; (3) slit/excision, the zona slit and herniating trophectoderm excised; and (4) hatch/excision, trophectoderm cells excised after spontaneous hatching.

RESULTS

Murine blastocysts were comparatively biopsied using one of four methods and contrasted to zona slit and nonmicromanipulated controls. Operative cellular injury was assessed by uptake of fluorescein isothiocyanate (FITC). Postoperative embryonic viability was assessed by blastocoele reexpansion and hatching inner cell mass development and trophectoderm plating. All techniques yielded cells available for genetic analysis.

CONCLUSIONS

The slit/excision technique and hatch/excision techniques exhibited lower operative injury and the higher postoperative viability than aspiration or incision. The slit/excision and the hatch/excision techniques, though requiring two operative steps, appear to be the least damaging of the four methods. Therefore, they should be most applicable to human blastocysts obtained either by extended culture in vitro or by uterine lavage.

Chemistry and biology of natural and designed enediynes

Ever since the initial reports of the enediyne anticancer antibiotics in the late 1980s, researchers from a number of disciplines have been devoting increasing attention to their chemistry, biology, and potential medical applications. Synthetic chemists and molecular designers have been engaged in attempts to synthesize these molecules and to model their unique architecture. Considerable efforts have been directed at understanding and mimicking the various processes involved in the targeting, activation, and DNA cleavage associated with these natural products. This review summarizes the main contributions to the field, with particular emphasis on work from our laboratories. Highlights include studies of the Bergman reaction, which is central to the mechanism of action of enediynes, the design and chemical synthesis of a number of these systems, and biological studies with selected molecules. Finally, the total synthesis of calicheamicin gamma 1I, the most prominent member of this class of naturally occurring compounds, is discussed.

Localization of the A1.12/9 antigen family to the neurones, putative sensory receptors and tegument of Schistosoma mansoni

The A1.12/9 antigen family were localized to the periphery of vesicle-like structures in neurones and in the putative sensory receptors of cercariae by immuno-electron microscopy. After transformation into schistosomula, the antigens were rapidly lost until, after 18 h, no immunoreactivity could be detected. Expression resumed at approximately 36 h post-transformation and had returned to high levels by 4 days post-infection. This level was maintained through to the adult worm stage. In 4 day lung schistosomula and in 14 day and 21 day liver schistosomula immunolabelling was observed within the matrix of the tegument itself and also in association with the tegumental membrane and vesicles within the tegument. These properties suggest that the A1.12/9 antigens may be involved in neuropeptide processing pathways. In particular, this family may represent the schistosome homologue of the granin family with which they share common properties and some sequence homology.

Virulence of a Bordetella pertussis strain expressing a mutant adenylyl cyclase with decreased calmodulin affinity

Bordetella pertussis, the pathogen responsible for whooping cough, produces a toxic calmodulin-sensitive adenylyl cyclase which enters animal cells and increases intracellular cAMP. A point mutant of B. pertussis with abolished adenylyl cyclase catalytic activity was over 1000-fold less pathogenic to newborn mice than wild-type bacteria, demonstrating the importance of the adenylyl cyclase for B. pertussis virulence (Gross et al.). The B. pertussis adenylyl cyclase is highly sensitive to calmodulin with an apparent Kd for calmodulin of approximately 1 nM. The importance of this high-affinity calmodulin binding for virulence in vivo was examined by the creation of a B. pertussis point mutant (Trp-242 to Glu-242) with 200-fold lower calmodulin affinity than the native enzyme. This mutant B. pertussis strain retained its virulence in a newborn mouse model of pertussis, but the time course for establishment of a lethal infection in vivo was significantly delayed for the mutant strain. These data illustrate that high-affinity calmodulin binding is not obligatory for the activity of this toxin but is important for the rate for establishment of a lethal infection.

Development and optimization of plaque assays for rat coronaviruses

Plaque assays under Sephadex or agarose overlays are described for rat coronaviruses (RCVs) grown in L2 mouse fibroblasts. A plaque assay using Sephadex was simple; however, viable plaques could not be collected for propagation, and fixation was necessary before evaluation. Plaque formation under agarose was optimized using diethylaminoethyl-dextran (DEAE-D) in the pre-treatment and absorption media and trypsin added to the absorption media and agarose overlay. The use of DEAE-D alone, trypsin alone or trypsin combined with DEAE-D significantly increased plaque numbers and visibility. Plaque numbers were highest when pre-treatment media contained DEAE-D, absorption media contained DEAE-D and trypsin, and the agarose overlay contained trypsin. The assay was useful for plaque isolation and quantification of sialodacryoadenitis virus (SDA), Parker's rat coronavirus (PRCV) and other coronavirus isolates from rats and its specificity was demonstrated by plaque-reduction neutralization testing. These methods will facilitate production of cloned virus stocks for study of RCV biology and virus quantification for in vitro and in vivo studies of RCVs.

Long-term study of cell-mediated responses to Borrelia burgdorferi in the laboratory mouse

Borrelia burgdorferi infection of disease-susceptible (C3H) and -resistant (BALB) mice resulted in impaired proliferation to both T- and B-cell mitogens up to 30 days after inoculation. Interleukin-2 and -4 production was also impaired, paralleling the T-cell response to concanavalin A. Impaired lymphocyte proliferation could not be attributed to diminished numbers of T or B cells and was found to depend on the lymphoid organ (spleen or lymph node) examined. Prostaglandin production accounted for part of this immune dysfunction. Attempts to assess antigen-specific proliferation to B. burgdorferi were inconsistent, and delayed-type hypersensitivity responses were not detected. Adoptive transfer of T-enriched cells from chronically infected donors failed to prevent infection and disease development in recipient C3H mice. The current study emphasizes caution in the study of B. burgdorferi antigen-specific assays and argues against the role of a vigorous T-cell response in Lyme borreliosis in infected laboratory mice.

Prevalence of viral antibodies and helminths in field populations of house mice (Mus domesticus) in southeastern Australia

A 13-month study of wild mice (Mus domesticus) in wheatlands in southeastern Australia contrasted changes in the seroprevalence of antibody to 13 viruses and the occurrence of helminths with changes in their population dynamics. Mice were seropositive for mouse hepatitis virus (MHV), rotavirus, minute virus of mice (MVM), mouse adenovirus (MAdV), reovirus (reo 3), and murine cytomegalovirus (MCMV). The seroprevalences of all but rotavirus varied significantly with time and increased with host density. Near the end of the study, host density declined rapidly and the seroprevalence of MVM and reo 3 increased significantly. These two viruses had low seroprevalence when host survival was high and high seroprevalence when host survival was low, indicating they may play a role in regulating mouse populations. In the case of MVM, there was evidence of a viral epizootic during the decline in mouse abundance. The prevalence of four helminths (Taenia taeniaeformis, Syphacia obvelata, and Vampirolepis spp.) differed significantly with time but showed no apparent association with host density. These findings highlight the need for further study on the effect of viruses on the population dynamics of mice.

Exacerbation of Pneumocystis carinii pneumonia in immunodeficient (scid) mice by concurrent infection with a pneumovirus

scid mice naturally infected with Pneumocystis carinii and inoculated with a normally apathogenic pneumovirus had significantly higher P. carinii cyst counts and developed significantly more severe P. carinii-related disease than did sham-inoculated, P. carinii-infected scid mice. P. carinii-free, virus-infected scid mice survived for 2 months despite high pulmonary virus titers. These results show that a respiratory virus infection can exacerbate P. carinii disease in an immunocompromised-rodent model.

In vivo studies with an "orphan" parvovirus of mice

A virus antigenically related to, but distinct from, minute virus of mice was assessed for infectivity in neonatal and weanling random-bred mice and was equally infectious for both age groups. The virus, designated a mouse "orphan" parvovirus (OPV), was also localized in tissues of experimentally infected random-bred, inbred, and immunodeficient mice by in situ hybridization. Hybridization signal was seen in exocrine and endocrine pancreas, abdominal lymph nodes, mesentery, intestine, and sporadically in other tissues of Sencar, C3H, and DBA mice inoculated as infants. In adult BALB/c severe combined immunodeficient (scid) mice, signal was seen in lung, liver, spleen, lymph nodes, and intestine but not in pancreas. Transmission of OPV by Sencar mice inoculated as infants was intermittent, whereas transmission by Sencar mice inoculated as weanlings was consistent during the first 2 weeks both by direct contact and by exposure to soiled bedding. The longest duration of transmission was 6 weeks among mice inoculated as infants. The results implicate a role for urinary, fecal, and perhaps respiratory excretion of virus, depending on host genotype and route of virus exposure. They also suggest that evaluation of pancreatic and immune function during acute infection is warranted.

Characterization of acute rat parvovirus infection by in situ hybridization

In situ hybridization and virus titration were used to characterize early stages of rat virus (RV) infection of rat pups after oronasal inoculation. Results suggest that virus enters through the lung and that early viremia leads rapidly to pantropic infection. Cells derived from all three germ layers were infected with RV, but those of endodermal and mesodermal origin were the predominant targets. Infection of vascular endothelium was widespread and was associated with hemorrhage and infarction in the brain. Convalescence from acute infection was accompanied by mononuclear cell infiltrates at sites containing RV DNA. Viral DNA was also detected in endothelium, fibroblasts and smooth muscle myofibers four weeks after inoculation. Further examination of these cells as potential sites of persistent infection is warranted.

Lethal exacerbation of Pneumocystis carinii pneumonia in severe combined immunodeficiency mice after infection by pneumonia virus of mice

Mice homozygous for the mutant allele scid (severe combined immunodeficiency) have been described as excellent models for Pneumocystis carinii (Pc) pneumonia (PCP), a major health problem in patients with acquired immune deficiency syndrome (AIDS) and other immunodeficiency states. Other microorganisms have been shown to infect AIDS patients simultaneously with Pc, but whether one opportunist is able to directly influence the pathogenicity of another has not been determined previously. We have deliberately coinfected scid mice (with extent Pc infection) with a variety of primarily pneumotropic viruses and bacteria and have identified pneumonia virus of mice as causing a dramatic increase in the density of Pc organisms and the morbidity due to PCP in immunodeficient scid mice. This finding has clinical significance in the management of PCP, in that the identification and treatment of coinfecting pneumotropic pathogens may be as important as treatment targeted at Pc. A search for other synergistic (or antagonistic) microorganisms and determination of their mechanism(s) of action in altering the progression of PCP is indicated.

A serologic survey for viruses and Mycoplasma pulmonis among wild house mice (Mus domesticus) in southeastern Australia

Plasma samples from 267 wild house mice (Mus domesticus) trapped at 14 sites in southeastern Australia were screened for antibody to 14 viruses normally associated with laboratory-reared rodents and to Mycoplasma pulmonis. Serologic prevalence was high for murine cytomegalovirus (99%, n = 94), murine coronavirus (95%), and murine rotavirus (74%). Samples from mice collected at all sites contained antibody to these viruses. The serologic prevalence was lower for mouse adenovirus, strain K87 (37%), parvovirus (33%), and reovirus type 3 (28%), with substantial site-to-site variation. Plasma from mice collected at 12 sites contained mouse adenovirus or reovirus antibody, and samples from mice at eight sites contained parvovirus antibody. Parvovirus-antibody positive mice were typically from high density populations or from low density populations that had recently declined from high density. Antibody to lymphocytic choriomeningitis virus (LCMV) and Sendai virus occurred at only three sites, and the serologic prevalence was very low (9.6% and 1.8%, respectively). All of the LCMV-positive mice were from northeastern New South Wales. The presence of this zoonotic virus in a mouse plague-prone region raises questions about human health risks resulting from cohabitation with large numbers of mice. It appeared that mouse populations at high density or declining from high density had higher prevalence of viral antibody than populations that had been at low or moderate density for some time. Thus, viral epizootics may occur among high-density populations and may be responsible for or precipitate declines in mouse density. These data raise the possibility of rodent viruses having potential as biological control agents.