Pathogenesis of infection with a virulent allotropic variant of minute virus of mice and regulation by host genotype

Neonates of various inbred strains of mice expressed three susceptibility phenotypes in response to infection with the lymphocyte-specific variant of minute virus of mice (MVMi). MVMi caused asymptomatic infections in C57BL/6 (B6) mice, lethal infections with intestinal hemorrhage in DBA/2 mice, and lethal infections with renal papillary hemorrhage in BALB/c, SWR, SJL, CBA, and C3H (H) mice. Sequential virus titration, histology, in situ hybridization with a full-length MVMi genomic probe, and immunohistochemistry for viral capsid antigen were used to compare the pathogenesis of MVMi infection in B6 and H mice. Peak infectious virus titers in heart, lung, liver, spleen, kidney and intestine did not differ between strains but brains of B6 mice, unlike H mice, were refractory to infection. Lesions in H mice consisted of renal papillary infarcts and accelerated involution of hepatic erythropoietic foci. No lesions were seen in B6 mice. In situ hybridization and immunohistochemistry indicated that three cell types were primary targets of MVMi; endothelium, lymphocytes, and hepatic erythropoietic precursors. Renal papillary infarcts in H mice were associated with virus replication in endothelial nuclei of the vasa recta. In contrast to the parity of infectious virus titers between strains, fewer cells in target organs of B6 mice were labeled with the MVMi probe then were labeled in H mice and fewer cells expressed viral capsid antigen. These results indicate (a) that the allotropic variants of minute virus of mice may be useful tools to dissect molecular mechanisms of parvovirus virulence, (b) that the virulence of MVMi for neonatal mice does not reside in its lymphotropism, and (c) that genetic susceptibility to lethal MVMi infection may result from overproduction of noninfectious virus products.

Feasibility of semen collection and cryopreservation during chemotherapy

Collection and cryopreservation of semen was undertaken in a 40-year-old man undergoing combination cyclophosphamide-doxorubicin-vincristine-prednisone chemotherapy for diffuse large cell lymphoma. Semen samples worthy of cryopreservation could be obtained through 39 days of therapy, with azoospermia observed after 70 days. Although pregnancy has not been attempted in the current case, reports by others suggest that normal outcomes can be expected with thawed semen collected during chemotherapy.

Predictive value of oropharyngeal cultures for identifying lower airway bacteria in cystic fibrosis patients

Identifying lower respiratory pathogens in young, non expectorating cystic fibrosis (CF) patients has been problematic. Bronchial secretions are difficult to obtain, and little is known about lower airway flora in these patients. We collected simultaneous bronchial and oropharyngeal specimens in 43 CF patients in optimal respiratory status, including both expectorating (17) and nonexpectorating (26) patients, to determine the predictive value of oropharyngeal cultures for identifying lower airway pathogens. An additional goal was to characterize the lower respiratory flora of these patients. Predictive values were defined as the proportion of oropharyngeal culture results that accurately reflected the results of bronchial cultures. Predictive values of positive oropharyngeal cultures in nonexpectorating patients were 83% (95% confidence interval 36 to 100%) for Pseudomonas aeruginosa and 91% (59 to 100%) for Staphylococcus aureus. Predictive values of negative oropharyngeal cultures were lower: 70% (48 to 86%) for R aeruginosa and 80% (52 to 96%) for S. aureus. A relatively high proportion of nonexpectorating CF patients less than 10 yr old had R aerusginosa (11 of 24, 46%) or Klebsiella species (5 of 24, 21%) in their lower airways. The isolation of Klebsiella was associated with younger age (p = 0.03) and recent administration of antistaphylococcal antibiotics (p = 0.05). Our results suggest that oropharyngeal cultures yielding R aeruginosa or S. aureus are highly predictive, but such cultures lacking these organisms do not rule out the presence of these pathogens in the lower airways of CF patients.

Superovulation fails to increase human blastocyst yield after uterine lavage

Uterine lavage affords the potential for non-invasive human blastocyst recovery, with obvious potential for preimplantation genetic diagnosis. In an effort to duplicate in women the multiple blastocyst recovery per cycle that can be achieved in several other species, we initiated a programme in which fertile women underwent superovulation, followed by lavage and embryo collection. We superovulated 15 fertile women, aged 21-40, in 29 cycles using one of four regimens. Insemination was by either intercourse or artificial intracervical donor insemination with cryopreserved sperm from men of proven fertility. In 28 of 29 cycles, the uterus was lavaged daily for 1, 2, or 3 days between 5 and 10 days after human chorionic gonadotropin (hCG) administration or luteinizing hormone (LH) surge. Almost total fluid volume was recovered in every lavage. There were no retained pregnancies and no complications. Surprisingly, only two morulae, one blastocyst, and four unfertilized ova were recovered. Thus, alterations in ovulation induction, insemination timing, or lavage techniques must be contemplated in order to increase the blastocyst yield and thus fulfil the potential of uterine lavage for preimplantation diagnosis.

Characterization of accessory cell function during acute infection of BALB/cByJ mice with mouse hepatitis virus (MHV), strain JHM

Earlier studies revealed defective concanavalin A-stimulated proliferation and cytokine production by spleen cells derived from BALB/cByJ mice acutely infected with mouse hepatitis virus (MHV), strain JHM. Based on those observations, assays of in vitro antigen-presenting cell (APC) function were undertaken. APC function of unfractionated spleen cells from individual MHV-infected mice was highly variable. Experiments using pooled spleen cells derived from MHV-infected mice revealed that adherent spleen cell APC function was impaired to a much greater degree than B cell APC function. Adherent cells derived from peritoneal exudates of infected mice exhibited an APC defect that was similar in magnitude to that observed for splenic adherent cells. Splenic B cells derived from acutely infected BALB/cByJ mice harbored infectious MHV. In contrast, lysates of adherent spleen cells from acutely infected mice did not kill intracerebrally inoculated neonatal mice, but did induce seroconversion among all survivors. Despite impairment of APC function of cells derived from MHV-infected donors, neither indomethacin nor accessory cells from uninfected control mice restored concanavalin A-induced proliferative responses of spleen cells collected from acutely infected mice. These results and those of earlier studies suggest that, although APC function is impaired, in vitro T cell dysfunction exhibited by spleen cells from MHV-JHM-infected donors is probably related to an inherent proliferative defect subsequent to T cell activation. Defective concanavalin A-stimulated proliferation does not appear to be secondary to accessory cell function suppression or to inhibitory factors secreted by accessory cells.

Monoclonal antibody to the receptor for murine coronavirus MHV-A59 inhibits viral replication in vivo

Because many strains of mouse hepatitis virus (MHV) infect laboratory mice, no effective vaccine has yet been developed. An alternative approach to control MHV disease is the use of a host cell receptor-targeted ligand. To address the potential usefulness of this approach, a monoclonal antibody directed against the host cell receptor for the coronavirus MHV-A59 was administered to infant mice that were then challenged oronasally with 10(4) intracerebral infant mouse median lethal doses of MHV-A59. Antibody treatment of virus-challenged mice resulted in lower proportions of mice with MHV-A59 in target organs and markedly reduced viral titers in these organs compared with mock-treated infected mice. Some antibody-treated infected mice survived for 7 days after viral challenge, whereas no mock-treated, infected mice survived beyond day 3 after viral inoculation. These results support a receptor-targeted approach to intervention in coronavirus disease.

Disposition of drugs in cystic fibrosis. I. Sulfamethoxazole and trimethoprim

The disposition of sulfamethoxazole and trimethoprim, after constant rate intravenous administration (10 mg/kg/hr sulfamethoxazole and 2 mg/kg/hr trimethoprim for 1 hour), was investigated in adult patients with cystic fibrosis (n = 7) and in age-matched healthy subjects (control subjects, n = 8). The total plasma clearance of sulfamethoxazole was found to be increased in cystic fibrosis (0.0262 +/- 0.0064 L/hr/kg) when compared with that found in control subjects (0.0188 +/- 0.0043 L/hr/kg). This increase in clearance was found to be primarily attributable to an increase in the metabolic clearance of sulfamethoxazole to N4-acetylsulfamethoxazole (0.00903 +/- 0.00247 versus 0.00355 +/- 0.00049 L/hr/kg) with the renal clearance of sulfamethoxazole remaining unchanged. These conclusions were not altered when the pharmacokinetic parameters were computed for the unbound drug or when they were normalized with respect to body surface area. These data indicate that, in cystic fibrosis, the enzymes mediating the metabolism of sulfamethoxazole to N4-acetylsulfamethoxazole, N-acetyltransferase(s), may be induced, activated, or both, or that the uptake of sulfamethoxazole by cells that metabolize sulfamethoxazole to N4-acetylsulfamethoxazole is enhanced. The total plasma clearance of trimethoprim was also found to be increased in cystic fibrosis (0.1808 +/- 0.0440 L/hr/kg) when compared with that found in control subjects (0.1139 +/- 0.0193 L/hr/kg). In contrast to sulfamethoxazole, this increase in clearance was found to be primarily attributable to an increase in the renal clearance of trimethoprim (0.1240 +/- 0.0299 versus 0.0720 +/- 0.0166 L/hr/kg). These data indicate that the tubular secretion of trimethoprim may be enhanced in cystic fibrosis.

Strain differences in in vitro rat hepatocyte unscheduled DNA synthesis (UDS): effect of UV is independent of strain while increased sensitivity is apparent using Fischer-344 instead of Sprague-Dawley rats

The unscheduled DNA synthesis (UDS) assay measures DNA repair following in vitro treatment of rat primary hepatocytes. This report compares the UDS response of primary hepatocytes from 2 widely used rat strains, the Fischer-344 (F344) and Sprague-Dawley (SD) strains. Ultraviolet (UV) light and 5 known genotoxic chemicals were evaluated in each strain in parallel experiments. The chemicals tested were 2-acetylaminofluorene (2-AAF), 4-aminobiphenyl (4-AB), benzidine, dimethylnitrosamine (DMN) and N-propyl-N'-nitro-N-nitrosoguanidine (PNNG). Four of these compounds (2-AAF, 4-AB, benzidine and DMN) require metabolic activation. Benzidine and PNNG were both negative using SD rat hepatocytes, but were weakly positive using F344 rat hepatocytes. In the first of 2 experiments, 4-AB was inconclusive in SD hepatocytes, but strongly positive in F344 cells. In the second experiment, 4-AB was positive in hepatocytes from both strains. 2-AAF was more strongly positive in F344 cells than in SD cells. DMN and UV light induced positive dose responses with little or no differences between strains. It is concluded that hepatocytes from F344 rats may be more sensitive, qualitatively and quantitatively, than hepatocytes from SD rats as indicators of UDS. This difference is not due to intrinsic differences in DNA repair mechanisms but is probably due to differences in drug-metabolizing enzymes between these strains. Thus, for routine screening, F344 rats are preferable for measurement of the in vitro UDS-inducing potential of compounds.

In vitro splenic T cell responses of diverse mouse genotypes after oronasal exposure to mouse hepatitis virus, strain JHM

Mortality rates among BALB/cByJ, A/JCr, C3H/HeSnJ, and C57BL/6NCr mice inoculated oronasally with mouse hepatitis virus (MHV) strain JHM, ranged from 25 to 67%. Spleen cells harvested from the first three genotypes at 5 days postinoculation proliferated poorly in response to concanavalin A stimulation and produced significantly less interleukin (IL) 2 than cells from uninfected control mice. The function of spleen cells harvested at 14 days postinoculation varied and was host genotype-dependent. Despite clinical signs among some infected C57BL/6NCr mice, spleen cell function was relatively unaffected. C57BL/10ScNCr, B10.A, and SJL/JCr mice remained clinically normal after MHV inoculation. Proliferation and IL2 production by cells from inoculated C57BL/10ScNCr and B10.A mice were similar to responses of their respective controls. In contrast, cells from inoculated SJL/JCr mice were hyper-responsive and produced peak levels of IL2 earlier than control cells. Among the seven genotypes tested, only BALB/cByJ and C3H/HeSnJ spleen cells produced detectable IL4 after primary stimulation with concanavalin A or after priming and restimulation. Primary IL4 production by cells from these two genotypes was significantly reduced if donors were inoculated with MHV 5 days prior to spleen harvest. IL4 production by cells from acutely infected BALB/cByJ mice was considerably enhanced by priming and restimulation.

Infection of BALB/cByJ mice with the JHM strain of mouse hepatitis virus alters in vitro splenic T cell proliferation and cytokine production

Earlier studies from this laboratory showed that infection of BALB/cByJ mice by a natural route with mouse hepatitis virus, strain JHM (MHV-JHM), results in functional splenic T cell suppression in vitro. This was evidenced by reduced concanavalin A-driven spleen cell proliferation and interleukin (IL)2 production measured after conventional intervals of cell culture (72 and 24 h, respectively). The purpose of the present work was to determine whether MHV-induced T cell dysfunction is kinetic or absolute and whether production of other T-cell derived cytokines is defective. Bioassays revealed that production of IL2, gamma interferon, and IL4 by spleen cells from acutely infected mice is suppressed and that some of the defects are kinetic as well as absolute. Proliferative responses of both CD4+ and CD8+ T cells were depressed, but neither cell type contained infectious virus. Cells that proliferated poorly in response to concanavalin A were fully capable of responding to specific virus stimulation. These results further emphasize the potential complications that MHV infection may pose to immunologic research using mice.

Trimethoprim resistance in Haemophilus influenzae is due to altered dihydrofolate reductase(s)

We characterized a highly purified preparation of the chromosomally encoded dihydrofolate reductase (DHFR) from a trimethoprim-susceptible (Tmp8; strain MAP) and two trimethoprim-resistant (TmpR) strains (MAP/47 and MAP/42) of Haemophilus influenzae. The enzymes were purified between 650- and 3000-fold by gel-filtration and dye-ligand chromatography. The apparent molecular mass of the three proteins was 18400 Da by PAGE under denaturing and nondenaturing conditions. Total enzyme activity was greater in all fractions from the TmpR strains compared with the Tmp8 isolate. The three enzymes had a similar Km for dihydrofolate (7, 9 and 5 microM) and NADPH (2, 5 and 6 microM). However, the Tmp IC50 (the concentration necessary for 50% inhibition of DHFR activity) for the Tmp8 strain MAP was 0.001 microM, whereas DHFR from the TmpR strains MAP/47 and MAP/42 had values of 0.1 microM and 0.3 microM respectively. The methotrexate IC50 of the MAP/42 DHFR was 0.06 microM in comparison with the enzyme from MAP (0.008 microM) and MAP/47 (0.007 microM). Isoelectric focusing indicated that the DHFR from MAP/42 had a different isoelectric point (pI 7.6) compared with the enzymes from MAP and MAP/47 (pI 7.3). Peptide mapping after digestion with trypsin revealed one major peptide fragment (7.9 kDa) in the DHFR of MAP and MAP/47 and three major tryptic fragments (7.9, 9.6 and 12.5 kDa) in DHFR from MAP/42. We conclude that trimethoprim resistance in H. influenzae results from overproduction of structurally altered DHFR(s).

Gamma interferon-mediated inhibition of Eimeria vermiformis growth in cultured fibroblasts and epithelial cells

The growth of Eimeria vermiformis within cultured murine fibroblastlike (L-929) or rat epithelial-like (RATEC) cells was inhibited by treatment of the cells with the appropriate recombinant gamma interferon. The effect was apparent as a reduction in both the initial numbers of intracellular sporozoites and, to a much greater extent, the numbers of subsequent developmental stages. Pretreatment of the host cells was more effective than treatment in the early postinvasive period, and recombinant gamma interferon had no effect on the development of the parasite if added 24 h or later after the inoculation of sporozoites. Incubation of sporozoites in medium containing recombinant gamma interferon in no way affected their ability to invade or to grow within host cells. These findings indicate that the inhibitory effects of recombinant gamma interferon on the growth of E. vermiformis are mediated via the host cell and are directed mainly against the transforming sporozoite, although the ability of the sporozoite to invade the host cell was also reduced to some extent. The later developmental stages were refractory to the effects of this lymphokine.

The role of gamma interferon in infection of susceptible mice with murine coronavirus, MHV-JHM

Infection of BALB/c mice with mouse hepatitis virus, strain JHM (MHV-JHM), at any of several intervals relative to ovalbumin (OVA) administration resulted in elevated OVA-specific IgG 2 a titers. Since gamma interferon (IFN) has been implicated as an up-regulator of IgG 2 a production, attempts were made to determine whether levels of this cytokine were modified in sera of infected mice. Serum IFN-gamma was not detected, but treatment of MHV-JHM-infected mice with monoclonal anti-IFN-gamma antibody resulted in high mortality with decreased survival times, enhanced virus titers in liver and spleen, and more severe virus-associated pathology, compared to mock-treated, infected mice. Immunotherapy with recombinant IFN-gamma ameliorated disease as reflected by mortality rates and virus titers in target organs.

Susceptibility of rodent cell lines to rat coronaviruses and differential enhancement by trypsin or DEAE-dextran

Cell lines of rodent origin were tested for susceptibility to infection with rat coronavirus (RCV), including sialodacryoadenitis virus (SDAV) and Parker's rat coronavirus (PRCV). LBC rat mammary adenocarcinoma cells were susceptible only if the cells were treated with diethylaminoethyl-dextran (DEAE-D). A recent report that RCVs grow well in L2 mouse fibroblast cells was confirmed and expanded. RCV infection of L2 cells was substantially enhanced by treatment of cells with trypsin but not by treatment with DEAE-D. Primary isolation of SDAV from experimentally infected rats was accomplished using trypsin-treated L2 cells. One of 13 additional cell lines tested (rat urinary bladder epithelium, RBL-02) supported growth of RCVs, and growth was slightly enhanced by DEAE-D, but not by trypsin. These refinements of in vitro growth conditions for RCVs should facilitate further studies of their basic biology and improve options for primary isolation.

Modulation of lethal and persistent rat parvovirus infection by antibody

Two day-old athymic (rnu/rnu) and euthymic (rnu/+) rat pups nursing immune or non-immune dams were inoculated oronasally with the Yale strain of rat virus (RV-Y). All athymic and euthymic pups (57/57) from immune dams remained clinically normal, whereas 51 of 66 athymic and euthymic pups from non-immune dams died within 30 days. Infectious RV was detected by explant culture in 12 of 15 surviving pups of both genotypes from non-immune dams 30 days after inoculation, but in none of the 57 surviving pups from immune dams. RV-Y DNA was detected by Southern blotting in kidneys of surviving athymic pups from non-immune dams but was not detected in pups from immune dams. Euthymic pups from immune dams appeared not to produce endogenous antibody to RV after virus challenge, whereas euthymic pups from non-immune dams produced high-titered RV immune serum. Pups of both genotypes given immune serum prior to or with RV were fully protected from disease and persistent infection, whereas pups given immune serum 24 hours after RV were partially protected. These studies show that RV antibody offers significant protection against lethal and persistent RV infection.

Duodenal pH in cystic fibrosis and its relationship to fat malabsorption

To investigate the relationship between duodenal pH levels and supplemental pancreatic enzyme function in cystic fibrosis, 18 children with this condition had pH recordings performed from the second and fourth part of the duodenum. Compared to age-matched controls, patients with cystic fibrosis had significantly longer periods below a pH of 4.0 in the postprandial period and significantly less time above pH 5.8. These values correspond to the pH levels at which lipase is irreversibly destroyed (pH 4.0) and enteric coating of enzyme supplements dissolves (pH 5.8). A significant relationship was found between the pH recordings from the fourth part of the duodenum and the degree of residual fat malabsorption while taking enteric-coated enzyme supplements. Four patients with an excessively acidic duodenum and residual fat malabsorption despite high-dose enzyme supplementation were treated with misoprostol (Searle), a known acid-reducing agent. There were significant improvements in both duodenal pH values and fat absorption. We conclude that there is a wide range of duodenal pH values found in patients with cystic fibrosis and that the efficiency with which enzyme supplements work is closely related to these pH levels. Administration of misoprostol to those patients with excessively acidic duodenal pH levels as well as residual malabsorption appears to be of benefit in improving both the excessively acidic pH levels and the fat malabsorption.

Susceptibility of laboratory mice to intranasal and contact infection with coronaviruses of other species

The susceptibility of laboratory mice to intranasal and contact infection with mouse hepatitis virus (MHV)-related coronaviruses was tested in infant CD1 mice. One day old mouse pups were inoculated intranasally with respiratory MHV-S, enteric MHV-Y, rat sialodacryoadenitis virus (SDAV), human coronavirus OC43 (HCV-OC43) or bovine coronavirus (BCV). Twenty-four hours later, they were placed in direct contact with age matched sham inoculated pups. Indices of infection in virus inoculated mice included lesions by histopathology and viral antigen by immunoperoxidase histochemistry in brain, lung, liver and intestine at 3 days after inoculation. Indices of infection in contact mice included mortality or seroconversion by 21 days after exposure. Infant mice were susceptible to infection with all five viruses. Transmission by direct contact exposure occurred with MHV and SDAV, but not HCV or BCV. Furthermore, adult mice were not susceptible to infection with HCV. Tissue distribution of lesions and antigen varied markedly among viruses, indicating that they do not induce the same disease as MHV. This study demonstrates that although these coronaviruses are antigenically closely related, they are biologically different viruses and disease patterns in susceptible infant mice can be used to differentiate viruses.

Urogenital, maternal and neonatal isolates of Haemophilus influenzae: identification of unusually virulent serologically non-typable clone families and evidence for a new Haemophilus species

A collection of 117 strains of Haemophilus influenzae, including 112 non-typable isolates recovered predominantly in the USA and France from genital, obstetric and neonatal sources, was characterized by the electrophoretic mobilities of 10 metabolic enzymes. Eighty-six distinctive multilocus chromosomal genotypes (electrophoretic types, ETs) were distinguished on the basis of allele profiles at the enzyme loci. Isolates of five allied biotype IV ETs were highly divergent from all other strains and hybridization of chromosomal DNA revealed that they undoubtedly represent a previously unrecognized species of Haemophilus. Isolates representing these ETs were recovered predominantly from obstetric infections and serious neonatal diseases and apparently possess specific tropism for the genital tract. Strains of these five ETs were present in samples from both the USA and France, but only in the USA did they cause bacteraemia and meningitis, an occurrence which probably reflects differences in patient management between the two countries. Although strains assigned to H. influenzae (sensu stricto) were strongly polymorphic in multilocus enzyme genotype, 69% of isolates recovered from patients with meningitis and/or septicaemia were assigned to only two clone families, a result suggesting that some serologically nontypable strains of H. influenzae originating from the genital tract are unusually virulent.

Duration of mouse hepatitis virus infection: studies in immunocompetent and chemically immunosuppressed mice

The duration of mouse hepatitis virus (MHV) infection was examined in mice inoculated intranasally with selected strains of MHV. Following inoculation with virulent MHV-JHM, genetically susceptible BALB/c mice and resistant CD1 mice had detectable virus in the brain at 1 month, but not later intervals up to 12 months. BALB/c mice infected with avirulent MHV-S or MHV-1 had no detectable virus in brains at 1 month or thereafter. Immunosuppression of BALB/c mice with treatment regimens of hydrocortisone acetate or cyclophosphamide at 1 and 2 months after infection with MHV-JHM did not activate detectable virus in liver or increase the prevalence or degree of brain infection. Immunosuppression with these drugs during the acute phase of MHV-JHM infection influenced MHV infection, based on virus quantification in livers, but timing of drug treatment relative to MHV infection was critical. Mice infected with MHV developed IgG serum antibody titers that persisted without decline for up to 1 year after infection. Antibody titers varied with mouse genotype and infecting virus. These studies, using intranasal inoculation, support the conclusions of others, using other routes of inoculation, that MHV infection is not persistent in adult, immunocompetent mice.

Pharmacokinetics of ticarcillin in patients with cystic fibrosis: a controlled prospective study

We compared the pharmacokinetics of ticarcillin at a dose of 120 mg/kg in 11 patients with cystic fibrosis to 11 control subjects matched for age and sex. The mean elimination half-life of ticarcillin in serum was 70.8 minutes in the control subjects and 53.1 minutes in the patients with cystic fibrosis. The total body clearance of ticarcillin was significantly higher in cystic fibrosis patients (65.6 +/- 22.0 versus 46.2 +/- 10.9 ml/min/m2 in control subjects; p = 0.017). The nonrenal clearance of ticarcillin was also significantly higher in patients with cystic fibrosis (24.8 +/- 11.1 versus 13.3 +/- 6.0 ml/min/m2 for the control group; p = 0.006). There was no significant difference in volume of distribution between the two groups. We concluded that the shorter elimination half-life and the higher total body clearance of ticarcillin in patients with cystic fibrosis are a result of an increase in both renal and nonrenal elimination.

An analysis of staining methods for the detection of Cryptosporidium spp. oocysts in water-related samples

The ability of five staining techniques, originally developed for the rapid identification of Cryptosporidium spp. oocysts in faecal samples, to detect oocysts in water and water-related samples was assessed. All the stains used (modified Ziehl Neelsen, auramine-phenol (Lempert), Wright-Giemsa, safranin-methylene blue and FITC-labelled monoclonal antibody) stained oocysts after storage in water for 2 months at 4 degrees C (71-89% of control values). Storage of oocysts below 0 degrees C greatly reduced the staining ability of auramine-phenol. With the exception of oocysts stored in raw and final waters, the histochemical stains proved less useful in detecting oocysts than the monoclonal antibody. Organisms of similar size and shape took up these stains, causing confusion in interpretation. Cold Ziehl Neelsen and the FITC-labelled monoclonal antibody were best at identifying oocysts from a waterborne outbreak. Screening with a fluorescent antibody, followed by confirmation with cold Ziehl Neelsen, where possible, are the currently recommended procedures for the detection of oocysts in water-related samples.

A comparison of fluorescein diacetate and propidium iodide staining and in vitro excystation for determining Giardia intestinalis cyst viability

The viability of 4 human isolates of Giardia intestinalis cysts using either the fluorogenic vital dyes fluorescein diacetate (FDA) and propidium iodide (PI) or in vitro excystation was assessed. Whereas viable cysts, as defined by in vitro excystation were present in each of the 4 isolates, cysts from only 3 of the 4 isolates took up the vital dyes. FDA consistently over-estimated cyst viability whilst PI under-estimated non-viable cysts when compared with in vitro excystation. Following in vitro excystation, both FDA and PI stained a proportion of unexcysted cysts indicating that FDA stained cysts which were incapable of excystation, whereas PI did not stain all cysts which were incapable of excystation. One human cyst isolate, which underwent in vitro excystation, could not be stained with either FDA or PI. In the absence of currently more specific fluorescent indicators of viability, PI alone could be used to determine the lower limit of nonviability in positive water-related samples, where small numbers of cysts are to be expected.

Genetic relatedness of antibiotic resistance determinants in multiply resistant Hemophilus influenzae

Antimicrobial resistance determinants and plasmids present in 10 multiply antibiotic-resistant strains of Hemophilus influenzae isolated from patients in different geographic regions of Spain were characterized. Conjugative plasmids with molecular sizes of 38-50 MDa encoded resistance to ampicillin, chloramphenicol, kanamycin, streptomycin, sulfamethoxazole, and tetracycline. Trimethoprim resistance was not linked to the other antibiotic resistance determinants and trimethoprim-resistant transconjugants and transformants lacked detectable plasmid DNA, suggesting that this determinant is chromosomal. Restriction endonuclease analysis revealed similarities among the plasmids, but several restriction patterns could be distinguished. Three hybridization patterns were found with DNA probes coding for H. parainfluenzae beta-lactamase and chloramphenicol-acetyltransferase. Resistance to kanamycin was due to drug modification by aminoglycoside-phosphotransferase (3')I. In Spain, it appears that multiple antibiotic resistance phenotypes in H. influenzae did not arise from acquisition of a single R plasmid; rather, both plasmid and chromosomal resistance evolved independently from several sources.

Psychiatric disorders in the first-degree relatives of probands with bulimia nervosa

Data from a family study of psychiatric disorders showed higher rates of major affective disorders, eating disorders, and alcoholism in first-degree relatives of 40 bulimic probands than in first-degree relatives of 24 control subjects. More importantly, the data showed higher rates of major affective disorders in relatives of bulimic probands who themselves had no history of major affective disorders than in relatives of control subjects. This significant finding indicates a familial relationship between bulimia nervosa and major affective disorders, which suggests the possibility of a common diathesis.

Endobronchial infection in cystic fibrosis

In symptomatic patients with cystic fibrosis, the recovery of bacteria in an inflammatory exudate from the lower respiratory tract is strong evidence of endobronchitis. It is not known when this chronic infection begins, the etiologic agents during infancy or the mechanism of evolution from Haemophilus influenzae and Staphylococcus aureus to Pseudomonas aeruginosa. Antibiotic administration to "suppress" the infection in relatively well patients is an unproven benefit. During an exacerbation of bronchitis, administration of appropriate antibiotics decreases sputum bacterial density and is accompanied by decreased amounts of indicators of inflammation in sputum: pulmonary function improves, particularly that reflecting medium to small airway status. In the future aggressive diagnostic procedures will be followed by therapeutic and prophylactic antibiotic administration conducted in a manner to minimize emergence of antibiotic-resistant bacteria. Adjunctive therapy, to minimize those aspects of the host response which inflict lung damage, will become standard.