Plant size, latitude, and phylogeny explain within-population variability in herbivory

Interactions between plants and herbivores are central in most ecosystems, but their strength is highly variable. The amount of variability within a system is thought to influence most aspects of plant-herbivore biology, from ecological stability to plant defense evolution. Our understanding of what influences variability, however, is limited by sparse data. We collected standardized surveys of herbivory for 503 plant species at 790 sites across 116° of latitude. With these data, we show that within-population variability in herbivory increases with latitude, decreases with plant size, and is phylogenetically structured. Differences in the magnitude of variability are thus central to how plant-herbivore biology varies across macroscale gradients. We argue that increased focus on interaction variability will advance understanding of patterns of life on Earth.

Identifying Environmental Risk Factors and Mapping the Distribution of West Nile Virus in an Endemic Region of North America

Understanding the geographic distribution of mosquito-borne disease and mapping disease risk are important for prevention and control efforts. Mosquito-borne viruses (arboviruses), such as West Nile virus (WNV), are highly dependent on environmental conditions. Therefore, the use of environmental data can help in making spatial predictions of disease distribution. We used geocoded human case data for 2004-2017 and population-weighted control points in combination with multiple geospatial environmental data sets to assess the environmental drivers of WNV cases and to map relative infection risk in South Dakota, USA. We compared the effectiveness of (1) land cover and physiography data, (2) climate data, and (3) spectral data for mapping the risk of WNV in South Dakota. A final model combining all data sets was used to predict spatial patterns of disease transmission and characterize the associations between environmental factors and WNV risk. We used a boosted regression tree model to identify the most important variables driving WNV risk and generated risk maps by applying this model across the entire state. We found that combining multiple sources of environmental data resulted in the most accurate predictions. Elevation, late-season humidity, and early-season surface moisture were the most important predictors of disease distribution. Indices that quantified interannual variability of climatic conditions and land surface moisture were better predictors than interannual means. We suggest that combining measures of interannual environmental variability with static land cover and physiography variables can help to improve spatial predictions of arbovirus transmission risk.

Mycoplasma pulmonisand Lymphoma in Bioassays in Rats

Lymphomas were reported to be induced in rats in bioassays of aspartame, methyl- tertiary-butyl ether (MTBE), and other chemicals conducted by a nonprofit cancer research organization. European regulatory authorities concluded that lymphomas in the aspartame study were caused by Mycoplasma pulmonis and suggested that this also was the case for the MTBE bioassay. To assess the role of M. pulmonis in these bioassays, we reviewed the tumor data for the aspartame and MTBE bioassays and, additionally, the organization's bioassay of methanol. For all 3 studies, the most frequently reported hematopoietic neoplasm was lympho-immunoblastic lymphoma, the most frequently affected organ was the lung, and, in almost half of the rats with this diagnosis, the lung was the only affected organ. Lesions diagnosed as lymphoma in published illustrations had pleomorphic cellular morphology and appeared to contain neutrophils. Information from these reports and other sources indicated that lesions typical of M. pulmonis disease were prevalent among the aspartame and MTBE study rats and that the rats were not specific-pathogen-free. Because the lymphoma type, cellular morphology, and organ distribution reported in these studies are atypical of lymphoma in rats, because lymphocyte and plasma cell accumulation in the lung is characteristic of M. pulmonis disease, and because M. pulmonis disease can be exacerbated by experimental manipulations, including chemical treatment, we suggest that a plausible alternative explanation for the reported results of these bioassays is that the studies were confounded by M. pulmonis disease and that lesions of the disease were interpreted as lymphoma.

A new hand-cooling device to enhance firefighter heat strain recovery

This study tested a new portable cooling device for fire fighting recovery. Participants (N = 8) walked and did arm curls (time-weighted VO(2): 1.6 L x min(-1) on a treadmill for 40 min in a heated chamber (wet bulb globe temperature: 33.7 degrees C; relative humidity: 40-45%) while wearing firefighter turn-out gear and self-contained breathing apparatus (SCBA). Immediately on finishing exercise, participants recovered for 40 min with either a hand-cooling device or seated passive recovery at an ambient temperature of 22 degrees C, 35% RH in a repeated-measures counterbalanced design. The cooling device had little impact on recovery during the first 30 min; however, compared with passive cooling, the cooling device resulted in significantly lower rectal temperature (T(re)) during the last 10 min. Relative to starting T(re) of the recovery period, Delta T(re) at 35 min had fallen 0.51 +/- 0.19 degrees C (passive) and 0.76 +/- 0.30 degrees C (active) (p = 0.03); and at 40 min Delta T(re) had fallen 0.63 +/- 0.17 degrees C (passive) and 0.88 +/- 0.31 degrees C (active) (p = 0.03). Cooling capacity of the device calculated from Delta T(re) over the whole recovery period averaged about 144% of passive. Reductions in heat storage enhance worker safety and performance in hot environments.

Effects of timing of pre-exercise nutrient intake on glucose responses and intermittent cycling performance

Objective. To evaluate the effects of two different pre-exercise feeding schedules (15 minutes and 60 minutes prior to exercise) of a mixed-nutrient nutritional bar on blood glucose levels and subsequent intermittent, high-intensity cycling performance. Methods. Ten moderately trained athletes participated in this counterbalanced, crossover, repeated measures study. Participants completed a 50-minute counterbalanced treatment intermittent exercise protocol. During one trial, participants consumed 400 ml water and a nutritional bar 15 minutes before the exercise session (15MPE). During another trial, participants consumed 400 ml water and a nutritional bar 60 minutes before the exercise session (60MPE). During a control trial (CON) participants consumed 400 ml water. Results. There were no significant differences in plasma glucose response at rest or during exercise among the three treatments (CON, 15MPE and 60MPE). There were no significant differences in mean power (MP) between the three trials. Conclusions. Pre-exercise nutrient feedings at 15 minutes or 60 minutes before exercise did not affect intermittent cycling performance or blood glucose concentration. These results suggest that the time of ingestion, within 1 hour prior to exercise, of a complex carbohydrate similar in composition and volume used in this study does not impact on performance. South African Journal of Sports Medicine Vol. 20 (3) 2008: pp. 86-90

Environmental enrichment of brown capuchins (Cebus apella): behavioral and plasma and fecal cortisol measures of effectiveness

No consensus exists about the quantity and variety of environmental enrichment needed to achieve an acceptable level of psychological well-being among singly housed primates. Behavioral and plasma and fecal cortisol measures were used to evaluate the effectiveness of four levels of toy and foraging enrichment provided to eight wild-caught, singly housed adult male brown capuchins (Cebus apella). The 16-week-long study comprised six conditions and began with a 4-week-long preexperimental and ended with a 4-week-long postexperimental period during which the subjects were maintained at baseline enrichment levels. During the intervening 8 weeks, the subjects were randomly assigned to a sequence of four 2-week-long experimental conditions: control (baseline conditions), toy (the addition of two plastic toys to each cage), box (access to a foraging box with food treats hidden within crushed alfalfa), and box & toy (the addition of two plastic toys and access to a foraging box). Behavioral responses to changes in enrichment were rapid and extensive. Within-subject repeated-measure ANOVAs with planned post hoc contrasts identified highly significant reductions in abnormal and undesirable behaviors (and increases in normal behaviors) as the level of enrichment increased from control to toy to box to box & toy. No significant behavioral differences were found between the control and pre- and postexperimental conditions. Plasma and fecal cortisol measures revealed a different response to changing enrichment levels. Repeated-measure ANOVA models found significant changes in both these measures across the six conditions. The planned post hoc analyses, however, while finding dramatic increases in cortisol titers in both the pre- and postexperimental conditions relative to the control condition, did not distinguish cortisol responses among the four enrichment levels. Linear regressions among weekly group means in behavioral and cortisol measures (n=16) found that plasma cortisol was significantly predicted by the proportions of both normal and abnormal behaviors; as the proportion of normal behaviors increased, the plasma cortisol measures decreased. Plasma cortisol weekly group means were also significantly and positively predicted by fecal cortisol weekly group means, but no behavioral measure significantly predicted fecal cortisol weekly group means. In sum, these findings argue strongly that access to a variety of toy and foraging enrichment positively affects behavioral and physiological responses to stress and enhances psychological well-being in singly housed brown capuchins.

Sequence analysis and initial characterization of two isozymes of hydroxylaminobenzene mutase from Pseudomonas pseudoalcaligenes JS45

Pseudomonas pseudoalcaligenes JS45 grows on nitrobenzene by a partially reductive pathway in which the intermediate hydroxylaminobenzene is enzymatically rearranged to 2-aminophenol by hydroxylaminobenzene mutase (HAB mutase). The properties of the enzyme, the reaction mechanism, and the evolutionary origin of the gene(s) encoding the enzyme are unknown. In this study, two open reading frames (habA and habB), each encoding an HAB mutase enzyme, were cloned from a P. pseudoalcaligenes JS45 genomic library and sequenced. The open reading frames encoding HabA and HabB are separated by 2.5 kb and are divergently transcribed. The deduced amino acid sequences of HabA and HabB are 44% identical. The HAB mutase specific activities in crude extracts of Escherichia coli clones synthesizing either HabA or HabB were similar to the specific activities of extracts of strain JS45 grown on nitrobenzene. HAB mutase activity in E. coli extracts containing HabB withstood heating at 85 degrees C for 10 min, but extracts containing HabA were inactivated when they were heated at temperatures above 60 degrees C. HAB mutase activity in extracts of P. pseudoalcaligenes JS45 grown on nitrobenzene exhibited intermediate temperature stability. Although both the habA gene and the habB gene conferred HAB mutase activity when they were separately cloned and expressed in E. coli, reverse transcriptase PCR analysis indicated that only habA is transcribed in P. pseudoalcaligenes JS45. A mutant strain derived from strain JS45 in which the habA gene was disrupted was unable to grow on nitrobenzene, which provided physiological evidence that HabA is involved in the degradation of nitrobenzene. A strain in which habB was disrupted grew on nitrobenzene. Gene Rv3078 of Mycobacterium tuberculosis H37Rv encodes a protein whose deduced amino acid sequence is 52% identical to the HabB amino acid sequence. E. coli containing M. tuberculosis gene Rv3078 cloned into pUC18 exhibited low levels of HAB mutase activity. Sequences that exhibit similarity to transposable element sequences are present between habA and habB, as well as downstream of habB, which suggests that horizontal gene transfer resulted in acquisition of one or both of the hab genes.

Genetic and biochemical comparison of 2-aminophenol 1,6-dioxygenase of Pseudomonas pseudoalcaligenes JS45 to meta-cleavage dioxygenases: divergent evolution of 2-aminophenol meta-cleavage pathway

Nitrobenzene is degraded to pyruvate and acetaldehyde by Pseudomonas pseudoalcaligenes JS45 via a reductive pathway, and by Comamonas sp. JS765 via an oxidative pathway. Although the initial reactions in the degradation of nitrobenzene by the two bacteria are totally different, the lower pathways are similar and converge at the level of 4-oxalocrotonate. In order to further investigate the biochemical properties and reveal the evolutionary relationships between the two lower pathways, the genes encoding the 2-aminophenol 1,6-dioxygenase were cloned and sequenced. 2-Aminophenol 1,6-dioxygenase from P. pseudoalcaligenes JS45 and catechol 2,3-dioxygenase from Comamonas sp. JS765 were able to act on both catechol and 2-aminophenol, but catechol was a suicide substrate of 2-aminophenol 1,6-dioxygenase. The activity of 2-aminophenol 1,6-dioxygenase was restored after removal of catechol and incubation with ascorbate and FeCl(2). Both the alpha-subunit (AmnA) and the beta-subunit (AmnB) of the dioxygenase from P. pseudoalcaligenes JS45 show a high degree of identity to the corresponding subunits of the ring-fission dioxygenase from Pseudomonas sp. AP-3: 67% for the alpha-subunit, and 84% for the beta-subunit. Sequence similarity studies suggest that the beta-subunits of both 2-aminophenol 1,6-dioxygenases are distantly related to homoprotocatechuate 2,3-dioxygenase from Escherichia coli strains W and C and then to catechol 2, 3-dioxygenase from Alcaligenes eutrophus. Four active-site-relevant histidines are conserved in AmnB, but not in AmnA. The lack of conserved histidines indicates the absence of an Fe(2+) binding site in AmnA, which explains the previous observations of only approximately one Fe(2+) per two subunits in the 2-aminophenol 1, 6-dioxygenases from P. pseudoalcaligenes JS45. The 2-aminophenol 1, 6-dioxygenase genes are located upstream of the 2-aminomuconic semialdehyde dehydrogenase gene, and a putative member of the YjgF protein family is upstream of the dioxygenase genes. Transcriptional analysis indicates that the YjgF-like protein, 2-aminophenol 1, 6-dioxygenase, and 2-aminomuconic semialdehyde dehydrogenase are coordinately transcribed. A putative ORF similar to part of the RNA helicase genes is downstream of the dehydrogenase gene. Both the novel organization of the genes and the phylogeny of the dioxygenases and dehydrogenase indicate that the 2-aminophenol pathway in P. pseudoalcaligenes JS45 represents an example of a distant divergent evolution of meta-cleavage pathways.

Antibody responses after Sendai virus infection and their role in upper and lower respiratory tract disease in rats

BACKGROUND AND PURPOSE

Sendai virus infection in rats is an excellent model for studying development and role of host defenses throughout the respiratory tract after this infection. Therefore, development of serum antibody responses and disease were studied.

METHODS

Forty-two anesthetized pathogen-free 3- to 4- week-old LEW/NCr rats were inoculated intranasally with Sendai virus. At postinoculation days 0, 2, 3, 5, 8, 10, and 14, rats were euthanized by administration of a pentobarbital sodium overdose followed by exsanguination. Serum was obtained from all animals, and nasal wash and bronchoalveolar lavage specimens were collected during selected experiments. An ELISPOT assay was used to measure numbers of Sendai virus-specific antibody-forming cells in respiratory tract lymphoid tissue.

RESULTS

Recovery from disease and clearance of virus from respiratory tract tissues coincided with development of serum antibody responses. Upper respiratory tract lymph nodes were the initial and major sites of appearance of antibody-forming cells. Immunoglobulin G was the predominant subtype of these cells during recovery from the infection and in rats resistant to infection. Passive transfer of antisera or specific IgG protected the lower but not the upper respiratory tract.

CONCLUSIONS

Circulating components of immunity have a major role in resistance and recovery from disease in the lower respiratory tract, whereas local responses are likely involved in protection of the upper respiratory tract. Local lymphoid tissues are the major production sites of IgG, which contributes to resistance to and recovery from respiratory tract diseases.

Effects of Mycoplasma fermentans incognitus on differentiation of THP-1 cells

Mycoplasma fermentans incognitus has been isolated from human tissue in patients both with and without AIDS who died of systemic infection. M. fermentans incognitus and other strains of M. fermentans have been associated with rheumatoid arthritis. While cell extracts of M. fermentans incognitus can induce changes in murine and human cells of the monocytic lineage, little is known about interactions of viable organisms with such cells. Because of the central role of macrophages in chronic inflammation, we examined the effects of M. fermentans incognitus on surface markers and functions of THP-1 cells, a well-characterized human monocytic cell line. This cell line has been used extensively in studies of macrophage differentiation, especially following exposure to phorbol esters. Changes in cell morphology, phagocytosis, rate of cell division, and selected surface markers were evaluated in cultures of THP-1 cells exposed to phorbol myristate acetate (PMA), M. fermentans incognitus, or both. As reported by other investigators, PMA induced THP-1 cells to differentiate into cells resembling tissue macrophages. M. fermentans incognitus only minimally affected changes induced by PMA, slightly increasing the percentage of cells positive for FCgammaRI and major histocompatibility complex (MHC) class II antigens. M. fermentans incognitus alone induced an incomplete arrest in the cell cycle at G0 phase, increased phagocytic ability, and enhanced expression of FCgammaRI, CR3, CR4, and MHC class II antigens.

Purification, characterization, and sequence analysis of 2-aminomuconic 6-semialdehyde dehydrogenase from Pseudomonas pseudoalcaligenes JS45

2-Aminonumconic 6-semialdehyde is an unstable intermediate in the biodegradation of nitrobenzene and 2-aminophenol by Pseudomonas pseudoalcaligenes JS45. Previous work has shown that enzymes in cell extracts convert 2-aminophenol to 2-aminomuconate in the presence of NAD+. In the present work, 2-aminomuconic semialdehyde dehydrogenase was purified and characterized. The purified enzyme migrates as a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with a molecular mass of 57 kDa. The molecular mass of the native enzyme was estimated to be 160 kDa by gel filtration chromatography. The optimal pH for the enzyme activity was 7.3. The enzyme is able to oxidize several aldehyde analogs, including 2-hydroxymuconic semialdehyde, hexaldehyde, and benzaldehyde. The gene encoding 2-aminomuconic semialdehyde dehydrogenase was identified by matching the deduced N-terminal amino acid sequence of the gene with the first 21 amino acids of the purified protein. Multiple sequence alignment of various semialdehyde dehydrogenase protein sequences indicates that 2-aminomuconic 6-semialdehyde dehydrogenase has a high degree of identity with 2-hydroxymuconic 6-semialdehyde dehydrogenases.

Bioethical aspects of HIV infection in children

The care of HIV-infected children is fraught with many bioethical conflicts and dilemmas that require careful attention if care is to be provided appropriately. Understanding of the interplay of such general principles as autonomy, nonmaleficence, confidentiality, and veracity helps to clarify the nature of specific conflicts. This article addresses both general principles and their specific applications to pediatric patients with HIV infection. It addresses these matters from the points of view both of patients and parents. It shows why conflict is practically inevitable, and it points the way toward prevention and resolution of conflict. Practical guidelines are provided in relation to the critical problem of disclosure of diagnosis to the patient.

Detection of urogenital mycoplasmal infections in primates by use of polymerase chain reaction

Urogenital mycoplasmal infections could affect use of primates as models for reproductive system studies and could affect reproduction in captive primates, but could be useful as animal models of similar human infections. We conducted a pilot study to assess detection of urogenital mycoplasmal infections in primates by use of polymerase chain reaction (PCR). Healthy animals were anesthetized, and vaginal, cervical, or endometrial and urethral swab specimens were collected from females and males, respectively. Specimens were tested by PCR supplemented with dot blotting and nonradiolabeled oligonucleotide probing for 16S rRNA sequences conserved among mollicutes. Specimens with positive results were tested by species-specific PCRs with primers for 16S rRNA sequences of Ureaplasma urealyticum and Mycoplasma hominis and for adhesin gene sequences of Mycoplasma genitalium. Spiked duplicate reactions were included as internal controls for each reaction. Results for 232 specimens from 166 animals indicate that naturally acquired urogenital infections are readily detected and suggest that urogenital mycoplasmal infections are common in laboratory primates (48/166 [29%] overall). M. hominis and U. urealyticum appeared to be common among the studied primates overall and especially in chimpanzees. Mycoplasmas other than M. genitalium, M. hominis, and U. urealyticum appeared to be at least as common as these three, with specimens from 18 of 48 animals (38%) having positive "generic" PCR results, but no positive results in species-specific PCRs.

Pathogenicity of cilia-associated respiratory (CAR) bacillus isolates for F344, LEW, and SD rats

We conducted experiments to test whether rats of F344, LEW, and SD strains differ in susceptibility to mycoplasma-free isolates of cilia-associated respiratory (CAR) bacillus, whether Mycoplasma pulmonis can affect expression of CAR bacillus disease, and whether isolates of CAR bacillus differ in virulence for rats. In the first experiment, 24 rats of each strain were inoculated intranasally with 10(7) bacilli of CAR bacillus X1428D/AS, and 24 rats of each strain were inoculated with sterile medium (controls). Eight weeks later, eight inoculated rats and eight control rats of each strain were euthanatized, eight inoculated and eight control rats were given 10(6.5) colony-forming units of M. pulmonis X1428D, and eight inoculated rats and eight control rats were sham inoculated. Four rats of each group were euthanatized 4 or 8 weeks after the second inoculation. Severity of lesions in nasal passages, middle ear, trachea, and lungs was assessed by scoring. Rats of all three strains given CAR bacillus had typical lesions of similar severity; M. pulmonis X1428D was avirulent and did not exacerbate CAR bacillus disease. In the second experiment, groups of eight rats of F344 and SD strains were given 10(5) or 10(7) CAR bacillus X1328E, X1428D/AS, or X2450D and euthanatized 8 or 16 weeks later. Isolates X1428D/AS and X2450D caused similar lesions in rats of both strains and at both doses, but CAR bacillus X1328E was avirulent. Rats of the tested strains are similarly susceptible to CAR bacillus disease, but CAR bacillus isolates differ in virulence.

Detection of Mycoplasma pulmonis in cilia-associated respiratory bacillus isolates and in respiratory tracts of rats by nested PCR

To improve the detection of Mycoplasma pulmonis contamination of isolates of cilia-associated respiratory (CAR) bacillus, we developed a nested PCR method using primers for 16S rRNA gene sequences. Of 140 samples of 16 different CAR bacillus isolates, 73 (52%) were inhibitory in the first PCR, as indicated by the absence of amplicons of the internal control, but only 11 of 140 (7.9%) were inhibitory in the second PCR. Of 27 samples known to contain M. pulmonis, only 12 (44%) were positive in the first PCR, but 25 of 27 (93%) were positive in the second PCR. Nested PCR also detected M. pulmonis in 21 of 61 (34%) CAR bacillus samples from which M. pulmonis could not be cultured and identified 2 additional M. pulmonis-contaminated CAR bacillus isolates. Of 359 respiratory and reproductive tract lavage samples from rats and mice, 35 (9.8%) were inhibitory in the first PCR, but only 15 (4.2%) were inhibitory in the second PCR. Of 72 lavage specimens from rats inoculated with an avirulent, poorly infective M. pulmonis strain, 14 (19%) were positive by nested PCR, but only 2 of 72 (2.8%) were positive by culture. Nested PCR also detected M. pulmonis in 14 of 20 (70%) paraffin sections of lung and trachea from rats and mice inoculated with CAR bacillus isolates known to contain M. pulmonis, whereas single PCR gave no positive results. We conclude that nested PCR is superior to single PCR or culture for detecting M. pulmonis, and that M. pulmonis is present in all but four CAR bacillus isolates in our collection that were from naturally infected rats; the four isolates that were exceptions were obtained from rats from a single colony.

Comparative severity of respiratory lesions of sialodacryoadenitis virus and Sendai virus infections in LEW and F344 rats

In several chronic diseases, lesions are more severe in LEW rats than in F344 rats. To determine whether or not acute viral diseases also are more severe in LEW rats than in F344 rats, we inoculated 6-7-week-old LEW and F344 rats with 10(7.2) cell culture infective units of sialodacryoadenitis virus or 10(4.7) infective units of Sendai virus. Twenty-four rats of each strain were given each virus. Lesions in nasal passages, tracheas, intrapulmonary airways, and pulmonary alveoli in 6 or 12 rats inoculated with each virus were assessed by scoring 5, 10, and 14 days after inoculation. Both viruses caused typical patchy necrotizing rhinitis, tracheitis, bronchitis, and bronchiolitis, with multifocal pneumonitis, in rats of both strains. Mean lesion indices for LEW rats given sialodacryoadenitis virus were significantly different from those for F344 rats for nasal passages on days 10 (0.999 vs. 0.680) and 14 (0.736 vs. 0.278), bronchi on day 5 (0.479 vs. 0.361), and alveoli on day 5 (0.677 vs. 0.275). Lesion indices for LEW rats given Sendai virus were significantly different from those for F344 rats for nasal passages on days 10 (1.000 vs. 0.611) and 14 (0.778 vs. 0.583); trachea on day 10 (0.625 vs. 0.028); bronchi on days 5 (0.476 vs. 0.331), 10 (0.123 vs. 0.013), and 14 (0.038 vs. 0); and alveoli on days 5 (0.413 vs. 0.114) and 10 (0.185 vs. 0.020). Thus, at the tested doses, both viruses caused more severe respiratory tract lesions in LEW rats than in F344 rats.

Gene expression and production of tumor necrosis factor alpha, interleukin 1, interleukin 6, and gamma interferon in C3H/HeN and C57BL/6N mice in acute Mycoplasma pulmonis disease

Studies were conducted to determine whether the production of various cytokines is associated with Mycoplasma pulmonis disease expression. Susceptible C3H/HeN and resistant C57BL/6N mice were inoculated intranasally with 10(7) CFU of virulent M. pulmonis UAB CT or avirulent M. pulmonis UAB T. Expression of genes for tumor necrosis factor alpha (TNF-alpha), interleukin 1 alpha (IL-1 alpha), IL-1 beta, IL-6, and gamma interferon (IFN-gamma) in whole lung tissue and TNF-alpha gene expression in bronchoalveolar lavage (BAL) cells was determined by reverse transcription-PCR using specific cytokine primers at various times postinoculation. In addition, concentrations of TNF-alpha, IL-1, IL-6, and IFN-gamma were determined in BAL fluid and serum samples at various times postinoculation. Our results showed that there was a sequential appearance of cytokines in the lungs of infected mice: TNF-alpha, produced primarily by BAL cells, appeared first, followed by IL-1 and IL-6, which were followed by IFN-gamma. Susceptible C3H/HeN mice had higher and more persistent concentrations of TNF-alpha and IL-6 in BAL fluid than did resistant C57BL/6N mice, indicating that TNF-alpha and possibly IL-6 are important factors in pathogenesis of acute M. pulmonis disease in mice. Serum concentrations of IL-6 were elevated in C3H/HeN mice, but not C57BL/6N mice, following infection with M. pulmonis, suggesting that IL-6 has both local and systemic effects in M. pulmonis disease.

Chronic respiratory mycoplasmosis in C3H/HeN and C57BL/6N mice: lesion severity and antibody response

Mycoplasma pneumoniae is a leading, worldwide cause of death and disability due to pneumonia. Mycoplasma pulmonis infection in mice is an invaluable model for the study of host defenses against respiratory mycoplasmas in vivo. C3H/HeN mice are much more susceptible to acute inflammatory lung disease due to M. pulmonis than C57BL/6N mice, but little is known about the chronic disease in these mouse strains. We infected C3H/HeN and C57BL/6N mice with 10(4) CFU of M. pulmonis UAB CT and evaluated them at weekly intervals by quantitative mycoplasma culture of nasal passages, trachea, and lungs, assessment of lesion severity in nasal passages, trachea, and lungs, and determination of serum immunoglobulin classes and subclasses by enzyme-linked immunosorbent assay. We found that C3H/HeN mice had 2 to 5 logs more organisms in their lungs and far more severe lung disease than C57BL/6N mice through 63 days postinfection. Although both strains of mice developed the same classes of antibody, C3H/HeN mice had much greater anti-M. pulmonis immunoglobulin G (IgG) responses in the IgG1 and IgG2a subclasses than C57BL/6N mice. These results suggest that adaptive immunity does not effect resolution of chronic mycoplasma infection and disease in the lungs.

In vitro effects of Mycoplasma pulmonis on murine natural killer cell activity

We evaluated the effect of coculture of virulent and avirulent strains of Mycoplasma pulmonis with mononuclear cells from resistant and susceptible strains of mice on natural killer (NK) cell activity against YAC-1 cells in a standard 4-h 51Cr-release assay. Endogenous NK activity was minimal in the specific-pathogen-free-mice without an external stimulus. There was no correlation between in vivo virulence of the mycoplasmas or host resistance and the in vitro stimulation of NK cell activity. Only two of the avirulent strains of M. pulmonis tested induced significant increases in NK cell activity, and virulent M. pulmonis increased activity only in cells from susceptible C3H/HeN mice.

Acute Mycoplasma pulmonis infection associated with coagulopathy in C3H/HeN mice

Experimentally induced infection with high doses of Mycoplasma pulmonis results in acute pneumonia characterized by severe pulmonary hemorrhage, edema, and, often, death in C3H/HeN mice. To determine whether specific disease manifestations were associated with coagulopathy, we measured serum fibrin, fibrinogen degradation products, and plasma fibrinogen concentrations in C3H/HeN mice infected with high doses of a virulent strain of M. pulmonis. We also examined the lungs and other tissues from infected mice for the presence of intravascular fibrin clots and other lesions. Increased concentrations of fibrinogen degradation products indicated that coagulopathy occurs in acute M. pulmonis infection; however, intravascular fibrin clots were not present. Rather than decreasing, as might be expected during a consumptive coagulopathy, fibrinogen concentrations increased. The hyperfibrinogenemia probably is associated with an acute phase response to M. pulmonis infection.

Role of neutrophils in breakdown of the blood-retinal barrier following intravitreal injection of platelet-activating factor

Breakdown of the blood-retinal barrier occurs in inflammatory conditions and in ischemic retinal diseases such as diabetic retinopathy. Platelet-activating factor (PAF) is a potent inflammatory mediator which increases vascular permeability. The purpose of this study was to determine if intravitreally-injected PAF would cause breakdown of the blood-retinal barrier and, if so, by what mechanism. Fluorescein angiography was performed before and at 0.5, 1, 2, 3 and 4 hr after PAF injection into the vitreous cavity of rabbit eyes and the eyes were enucleated immediately for light and electron microscopy. Slow flowing thrombi were observed in all PAF-injected eyes. Complete vascular occlusion was observed in 10 of 16 eyes after 3 and 4 hr. There was no fluorescein leakage in any of eyes before or at 0.5 or 1 hr after PAF injection. Fourteen of 20 eyes had fluorescein leakage at 2, 3 and 4 hr after PAF injection. The extent of fluorescein leakage correlated with the degree of polymorphonuclear leukocyte (PMN) margination, disruption of the endothelial cell layer, infiltration into vascular walls and migration into the vitreous cavity. PMNs appeared to migrate by both intercellular and transcellular routes across the endothelium. Pretreatment of rabbits with a PAF inhibitor, BN52021, prevented most of the abnormal findings.

Effects of viral and mycoplasmal infections, ammonia exposure, vitamin A deficiency, host age, and organism strain on adherence of Mycoplasma pulmonis in cultured rat tracheas

Adherence to host cells is thought to be a pathogenetic mechanism in mycoplasmal diseases, thus, factors affecting adherence could affect disease expression. To determine whether factors that affect expression of Mycoplasma pulmonis respiratory disease in rats alter adherence of the organism to respiratory epithelium, we studied adherence of radiolabelled M. pulmonis in perfused whole rat tracheas. Adherence was significantly increased in tracheas from rats with sialodacryoadenitis virus infection or vitamin A deficiency (103 +/- 16% and 112 +/- 29% of control means, respectively), but Sendai virus infection, ammonia exposure, and host age (40 versus 8 weeks) were not associated with increased adherence. We also assessed the relationship between adherence and virulence of M. pulmonis strains. The virulent strain 5782C was more adherent (51 +/- 7%) than the type strain, PG34(Ash), and a polystyrene-adherent, hemadsorbing UAB CT subclone was more adherent (229 +/- 40%) than a UAB CT subclone that does not adhere to polystyrene or erythrocytes. PG34(Ash) and the UAB CT subclones caused rhinitis only; however, the adherent UAB CT subclone caused significantly more severe rhinitis than either the nonadherent subclone or PG34(Ash) as determined by scoring of histologic sections. To determine whether M. pulmonis itself induces changes in respiratory epithelium resulting in enhanced adherence, we studied adherence in tracheas from rats inoculated with M. pulmonis 3 weeks earlier. Adherence was increased 64 +/- 22%, compared with that in tracheas from control rats. Adherence in infected tracheas treated with tetracycline for 2 days was not increased, indicating that M. pulmonis-induced changes in epithelial adherence are rapidly resolved after elimination of infection.

Cultivation of cilia-associated respiratory bacillus in artificial medium and determination of the 16S rRNA gene sequence

Cilia-associated respiratory (CAR) bacillus, an unclassified gliding bacterium associated with respiratory disease in rats, mice, and rabbits, has previously been cultivated only in embryonated chicken eggs, cell culture, or cell culture medium supplemented with conditioned medium from cultured tracheas. A reference strain of CAR bacillus, originally isolated in eggs, grew in cell culture flasks as adherent individual bacilli and ropy, whorled fascicles in cell culture media supplemented only with fetal calf serum. Using Dulbecco's minimal essential medium, we isolated CAR bacillus from naturally infected rats and a naturally infected rabbit and from experimentally inoculated mice and rats. Isolates were maintained for up to 20 passages. Isolates from rats were similar in morphology to the reference strain, but most were more actively motile and formed pincushion-like aggregates. The rabbit bacilli were smaller and formed fewer aggregates. DNAs of rat isolates differed only slightly in restriction fragment patterns from that of the reference strain, whereas that of the rabbit isolate was distinctly different. Cultures of CAR bacilli of all strains from rats contained Mycoplasma fermentans, Mycoplasma pulmonis, or both, and cultures of the CAR bacillus from the rabbit contained an unidentified arginine-utilizing mycoplasma. The sequence of the 16S rRNA gene of the reference strain was determined by amplification by polymerase chain reaction, cloning of the product, and sequencing by the dideoxynucleotide chain termination method. Comparison of the sequence with sequences in the GenBank data base indicated that CAR bacillus is a unique organism most closely related to Flavobacterium ferrugineum and Flexibacter sancti.

Interactions of mycoplasmas with B cells: antibody production and nonspecific effects

Interactions between mycoplasmas and B cells consist primarily of the development of specific antibody and of nonspecific interactions with B lymphocytes or antibody. Antibody responses are important in the resistance to mycoplasmal disease in both humans and animals. However, the ability of mycoplasmas to survive in their host despite vigorous responses suggests that these play a limited role in the host's recovery from infection. Antibody also may prevent dissemination of mycoplasmal infections from mucosal sites and may account for the appearance of systemic mycoplasmal infections in immunocompromised patients. In some cases, antibody responses may contribute to disease pathogenesis through the development of hypersensitivity responses or the deposition of immune complexes. In addition, nonspecific interactions between mycoplasmas and B lymphocytes have been implicated in disease pathogenesis, possibly leading to autoimmune reactions, modulation of immunity, and/or promotion of lesion development. For example, several mycoplasmas, including Mycoplasma pneumoniae and Mycoplasma pulmonis, are able to activate B cells polyclonally in vitro and in vivo, but the mechanisms and consequences of these responses have yet to be defined. In addition to activating B lymphocytes, mycoplasmas are capable of producing chemotactic factors, Fc receptors, and immunoglobulin proteases that may also be involved in lesion development and/or survival of the organisms. Thus, both specific and nonspecific interactions of mycoplasmas with B cells can have important effects on disease progression, especially since many mycoplasmal infections are chronic and the cumulative effect of these interactions may be substantial.

IDDM patients' sera recognize a novel 30-kD pancreatic autoantigen related to chymotrypsinogen

We have examined, by western immunoblot analysis, the sera of 16 insulin-dependent diabetes mellitus patients (IDDM) for the presence of autoantibodies against proteins extracted from islet-cell enriched preparations of normal human pancreata. A novel putative autoantigen recognized by late stage IDDM patients sera was identified, and its amino acid sequence was partially determined. Islets of Langerhans were partially purified by a modified collagenase digestion procedure, and subsequent protein extracts were fractionated by one-dimensional or two-dimensional polyacrylamide gel electrophoresis (1-D or 2-D SDS-PAGE). Immunoblot analysis revealed a 30-kD species which was recognized by 4 of 16 IDDM patients sera, but none of 16 normal sera. The 30-kD protein, appeared as a single band on 1-D SDS-PAGE, but was resolved on 2-D gel electrophoresis as several distinct protein species with different isoelectric points (pI's), ranging from 7 to 9. The amino terminal sequence of one such species was partially determined by microsequencing, and the second through the fourteenth amino acids were found to be identical to the corresponding sequence in human chymotrypsinogen. The fifteenth through the eighteenth amino acids were different from the known chymotrypsinogen sequence. This region corresponds with the site that is cleaved to activate chymotrypsinogen. Based on the size and sequence homology, this antigen appears to be related to chymotrypsinogen. We conclude that this 30-kD species may be an autoantigen in some late stage IDDM patients.

Pulmonary clearance of Mycoplasma pulmonis in rats with respiratory viral infections or of susceptible genotype

We sought to determine whether or not increased severity of bronchopulmonary disease due to Mycoplasma pulmonis infection in rats with respiratory viral infections and in rats of susceptible genotype could result from altered pulmonary clearance. Pathogen-free rats were exposed to aerosols of radiolabeled M. pulmonis and the numbers of M. pulmonis colony-forming units, and amounts of radiolabel in the lungs were determined immediately after exposure or 4 hours later. Intrapulmonary killing of M. pulmonis during the 4-hour interval was determined from decreases in ratios of colony-forming units to radiolabel, and physical clearance was determined from decreases in radiolabel. Neither intrapulmonary killing nor physical clearance differed between control F344 rats and F344 rats inoculated with Sendai virus or sialodacryoadenitis virus, or between F344 and LEW rats. Rates of intrapulmonary killing and physical clearance were 64 +/- 3% and 44 +/- 2%, respectively (overall means +/- standard error).

Infection-induced airway fibrosis in two rat strains with differential susceptibility

Chronic infections play a significant role in the morbidity and mortality of patients with chronic airflow limitation. By stimulating airway inflammation, persistent infection has the potential to cause airway fibrosis. However, in patient this condition is most typically found in lungs damaged by other factors, such as smoking, abnormal secretions, or barotrauma. We report the characterization of Mycoplasma pulmonis infection-induced lung fibrosis in two immunocompetent rat strains with no preexisting lung disease. The fibrosis was predominantly in the airways, as demonstrated by the findings for infected animals of increased airway inflammation, airway fibrosis, and airway wall thickness, which correlated with the collagen content of the lungs. Also, the physiological alterations were the opposite of those found in interstitial fibrosis, with a positive correlation between lung compliance and collagen content. The airway fibrosis was noted earlier and to a greater extent in Lewis rats than in Fisher rats, and this result apparently was related to regulation of the inflammatory response. Airway wall thickness, airway inflammation, and airway fibrosis are commonly reported in tissue specimens from patients with chronic airway diseases and have been shown to correlate with airflow limitation in patients with chronic obstructive pulmonary disease. Thus, this model may be useful in furthering our understanding of the role of chronic infection and airway inflammation in airflow obstruction.

Decreased intrapulmonary killing of Mycoplasma pulmonis after short-term exposure to NO2 is associated with damaged alveolar macrophages

Previous studies have shown that exposure of pathogen-free C57BL/6N mice to 5 or 10 ppm NO2 increases the severity of murine respiratory mycoplasmosis and that this effect is associated with decreased intrapulmonary killing of Mycoplasma pulmonis. The purposes of the present studies were to determine the effects of doses of NO2 lower than 5 ppm on pulmonary clearance and to provide experimental links between NO2 exposure, defects in intrapulmonary killing, and alterations in alveolar macrophages. Exposure to less than 5 ppm NO2 had no effect on intrapulmonary killing of M. pulmonis. Bronchoalveolar lavage cells killed M. pulmonis in vitro only if they were allowed to associate with mycoplasmas in vivo. Prior exposure to NO2 abrogated killing in this in vivo-in vitro model. More than 95% of the BAL cells were macrophages, and more than 98% of the cell-associated mycoplasmas were on or in alveolar macrophages. Immediately after exposure, the viability of alveolar macrophages was 89 +/- 4% in the control group, 56 +/- 19% in the group receiving M. pulmonis alone, 23 +/- 7% in the group receiving 10 ppm NO2, and 16 +/- 6% in the group receiving both M. pulmonis and NO2 exposures. Viability was significantly decreased following exposure to 10 and 5 ppm NO2 but not following exposure to 2 ppm. Both viability and intrapulmonary killing were depressed at 3 days after exposure to NO2 but were normal by 7 days after exposure. The cellular target of NO2 exposure in relation to intrapulmonary killing of M. pulmonis appears to be the alveolar macrophages.

Mycoplasma pulmonis possesses a novel chemoattractant for B lymphocytes

Mycoplasma pulmonis causes chronic murine respiratory mycoplasmosis, which is characterized by extensive peribronchial and perivascular infiltration of mononuclear cells, including B lymphocytes. B-lymphocyte recruitment into sites of inflammation is presently poorly understood but must involve directed chemotaxis of these cells in response to some external recruitment stimulus. In these studies, picogram amounts of M. pulmonis membrane protein were found to possess potent chemoattractant activity for resting rat B lymphocytes. This report is the first description of a bacterially derived chemoattractant for B lymphocytes and offers a unique opportunity to study regulation of B-lymphocyte recruitment to a site of chronic pulmonary inflammation. Furthermore, M. pulmonis membrane activation of fresh rat serum was found to produce a potent stimulus for recruitment of peritoneal and alveolar macrophages. M. pulmonis-mediated recruitment of lymphocytes and macrophages may play a significant role in the pathogenesis of murine respiratory mycoplasmosis, a role in which organisms on the bronchiolar epithelial surfaces may release proteins which can directly or indirectly promote chemotaxis of inflammatory cells from the circulation.

Early experience with laser disc decompression. A percutaneous method

A study over an 18-month period involved 40 patients with a contained HNP who underwent laser-assisted percutaneous lumbar discectomy utilizing KTP/532. Access to the disc was via an 18-gauge probe followed by dilating cannulas under fluoroscopic control. A 400 um quartz fiber was utilized. The laser power was set between 10 and 15 watts and the exposure duration at 0.5 seconds and repeated with intervals of 0.5 seconds. Two of six patients required an open conventional L4-5 discectomy; four refused additional surgery. These failures are considered probably secondary to a subligamentous location of disc. Based upon early results, laser-assisted percutaneous lumbar discectomy with KTP laser appears to be a viable alternative to automated percutaneous discectomy in selected cases and perhaps an improvement over other techniques.

Murine respiratory mycoplasmosis: a model to study effects of oxidants

Previous studies have shown that exposure to nitrogen dioxide at concentrations of 5 and 10 parts per million (ppm) decreases intrapulmonary killing of Mycoplasma pulmonis, and that this decrease is related to increased lung lesions and mortality. The specific objectives of the present study were to titrate the effects of nitrogen dioxide on pulmonary clearance of M. pulmonis, determine the mechanisms by which this organism is killed within the lungs, and determine the target that the nitrogen dioxide affects. Pathogen-free C57BL/6N mice were exposed to 0, 0.5, 1, 2, or 5 ppm of nitrogen dioxide (contamination with other oxides of nitrogen compounds was 5% or less) for four hours and then immediately were exposed to aerosols of viable, radiolabeled M. pulmonis strain UAB CT. One-half of the animals in each group were killed immediately after exposure to the infectious aerosols, and the rest were killed 24 hours later. The amount of radioactivity and the number of viable M. pulmonis were determined for each group. Exposure to less than 5 ppm of nitrogen dioxide had no effect on intrapulmonary killing of M. pulmonis, although exposure to 1 ppm of nitrogen dioxide did increase mechanical removal. We were unable to develop a completely in vitro mycoplasma killing method. However, we were able to demonstrate the in vitro killing of M. pulmonis that had been allowed to associate with alveolar macrophages in vivo. Thus, mouse lungs contain unidentified factors that allow cells to kill M. pulmonis. Furthermore, we obtained evidence that suggests that prior exposure to nitrogen dioxide abrogates killing in these experiments. We also have shown that exposure to nitrogen dioxide does not increase the protein content of bronchoalveolar lavage fluid. Using immunofluorescence, more than 95% of the cells recovered by lavage were macrophages; with double-label immunofluorescence, more than 98% of the cell-associated mycoplasmas were on or in alveolar macrophages. In assessing the cytological parameters of lung lavage cells from mice exposed to nitrogen dioxide, M. pulmonis, or both, we found that both insults affected the viability of recovered macrophages. Viability immediately after exposure as measured by trypan blue exclusion or by fluorescein diacetate uptake, was 89% +/- 4% and 88% +/- 4% in the control group, respectively; 56% +/- 19% and 64% +/- 11% in the group receiving M. pulmonis alone; 23% +/- 7% and 48% +/- 9% in the group receiving nitrogen dioxide alone; and 16% +/- 6% and 25% +/- 6% in the group receiving both M. pulmonis and 10 ppm nitrogen dioxide exposures.(ABSTRACT TRUNCATED AT 400 WORDS)

Specific and nonspecific antibody responses in different segments of the respiratory tract in rats infected with Mycoplasma pulmonis

Murine respiratory mycoplasmosis resulting from Mycoplasma pulmonis infection in rats provides a useful model for the study of immunological and inflammatory mechanisms operative in the respiratory tract. We have previously shown that LEW rats develop more severe disease than do F344 rats. To further study the production of antibody responses in chronic respiratory disease due to M. pulmonis infection, we examined the distribution and development of M. pulmonis-specific antibody-forming cells (AFC) in different segments of the respiratory tracts of infected LEW and F344 rats. In these studies, the upper respiratory nodes were the initial site of antibody production after infection and remained the major site for recovery of AFC. Since infected LEW rats had equal or higher numbers of AFC than did infected F344 rats, these results suggest that the level of local antibody production alone is not responsible for the decreased susceptibility of F344 rats to murine respiratory mycoplasmosis. The differences in total antibody responses appear to be due to the greater numbers of cells recovered from the tissues of infected LEW rats compared with those recovered from F344 rats, suggesting that LEW rats may have greater production of chemotactic factors. Also, we demonstrate that nonspecific activation and/or recruitment of B cells occurs in the respiratory tracts of both LEW and F344 rats after infection with M. pulmonis.

The effects of three serotypes of Ureaplasma urealyticum on spermatozoal motility and penetration in vitro

The effects of incubation of spermatozoa with three serotypes of Ureaplasma urealyticum on spermatozoal motility and penetration in vitro were investigated. Using computer-assisted video microscopy, three parameters of motility were determined: individual path lengths, individual vectorial distances, and percentage motility. Polyacrylamide gels were used as a medium for assessment of spermatozoal penetration. Ureaplasma-infected spermatozoa did have significantly greater path lengths and individual distances than did uninfected controls, but ureaplasma infection had no significant effect on percentage motility. Overall, there were no significant differences in penetration distances between ureaplasma-infected spermatozoa and their corresponding uninfected controls. Our conclusion is that the ureaplasmas did not adversely affect motility or penetration when spermatozoa were incubated with ureaplasmas for 45 minutes at ureaplasma:sperm ratios as high as 100:1.

The Sunglass Standard and its rationale

This paper reports on the 17-year development of the current Z80.3 Sunglass Standard. The dioptric tolerances of +0.125 to -0.25 D power, 0.125 D astigmatism, 0.25 delta prism, and 0.18 D power imbalance are based on research by optometry's leaders. The traffic signal and luminous transmittance requirements are the result of study of the literature and original research. There has been much misunderstanding regarding the UV transmittance specifications. They too were exhaustively researched and discussed. That work is reviewed in detail. New equations for calculating exposures are presented with sample spectra. Graphic evaluations of severe risk exposures are presented. They show that based on the accepted criteria, for reasonable assumptions the Standard offers a 10x margin of safety. Studies of retinal risk indicate the Standard provides ample protection. Some criteria need further study. Potential problems are based on the fact that some sunglasses are too dark for driving and that use of ordinary sunglasses for sports provides inadequate protection from injuries.

Serum antibody does not account for differences in the severity of chronic respiratory disease caused by Mycoplasma pulmonis in LEW and F344 rats

Chronic respiratory disease in rats, resulting from Mycoplasma pulmonis infection, is useful in the study of the immunological mechanisms in similar inflammatory diseases and provides a unique opportunity to study the interactions between systemic and mucosal immune systems in a naturally occurring infection. The present study examined the serum antibody responses to M. pulmonis in strains of rats which differ in disease progression and severity; LEW rats developed more severe disease than did F344 rats. Serum antibody responses were evaluated as to their levels, isotypes, and antigens recognized. Infected LEW rats produced greater or equal levels of the major classes of serum antibody to M. pulmonis than did infected F344 rats, suggesting that development of serum antibody responses alone does not resolve lesions and is not responsible for the difference in disease severity found in LEW and F344 rats. Although LEW rats produced higher responses in all subclasses of immunoglobulin G (IgG), the specific IgG response of LEW rats was composed predominately of IgG1 and IgG2a subclasses, while IgG2b was the major component of the IgG response in F344 rats. Finally, LEW rats responded more quickly to M. pulmonis antigens than did F344 rats, and there was no difference in the antigens eventually recognized by each strain, confirming previous work which suggested that LEW rats do not exhibit an unresponsiveness to a specific antigen(s) of M. pulmonis.

Upper respiratory tract is the major site of antibody production in mycoplasmal induced chronic respiratory disease

Chronic respiratory disease in rats, resulting from Mycoplasma pulmonis infection, provides a unique opportunity to study the interactions between systemic and mucosal immune systems in a naturally occurring infection of the respiratory tract. In the present studies, an ELISPOT assay specific for the determination of numbers of anti-M, pulmonis antibody forming cells (AFC) was developed. Using this assay, the numbers of IgG, IgM, and IgA AFC in respiratory and nonrespiratory associated lymphoid tissues were determined. The lymphoid tissues associated with the upper respiratory tract, which includes nasal passages and lymph nodes which drain various portions of the upper respiratory tract, were the major site of antibody production. Antibody responses within the lung were minimal. IgM and IgA were the major antibody isotypes produced in each of the tissues examined.

Short-term exposure to nitrogen dioxide enhances susceptibility to murine respiratory mycoplasmosis and decreases intrapulmonary killing of Mycoplasma pulmonis

In C57BL/6N and C3H/HeN mice known to be free of all murine pathogens and matched for age, sex, microbiologic, and environmental factors, exposure to NO2 for 4 h prior to exposure to infectious aerosols of Mycoplasma pulmonis resulted in potentiation of murine respiratory mycoplasmosis (MRM). In the C57BL/6N mice, NO2 increased the incidence of death, incidence of gross lung lesions, and incidence of microscopic lung lesions, but did not increase the incidence of infection in the lungs. Nitrogen dioxide affected the C3H/HeN mice (a strain known to be more susceptible than the C57BL/6N strain to MRM) similarly, with the exception that the incidence of death and microscopic lesions were not affected in this strain at the concentrations of M. pulmonis used. Exposure to the oxidant also increased the severity of microscopic lesions and the numbers of Mycoplasma organisms in the lungs of both mouse strains. Thus, NO2 appeared to affect host lung defense mechanisms responsible for limiting the extent of infection. The NO2 exposure level required to produce potentiation varied with the genetic background of the host, the number of Mycoplasma organisms administered, and the end point measured. In further experiments in C57BL/6N mice, exposure to 5 or 10 ppm of NO2 for 4 h prior to infection with aerosolized, radiolabeled M. pulmonis reduced clearance of these organisms from the lungs over a 72-h time period. Nitrogen dioxide exposure did not change the rate of physical removal of Mycoplasma organisms from the lung. Reduced clearance was due to impaired intrapulmonary killing of Mycoplasma organisms in NO2-exposed mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Ureaplasma urealyticum pneumonia: experimental production and demonstration of age-related susceptibility

Two different strains of Ureaplasma urealyticum isolated in pure culture from the lungs of newborn human infants were shown to produce an acute, self-limiting, interstitial pneumonia in newborn C3H/HeN and C57BL/6 mice that were free of other respiratory pathogens. Lesion severity peaked 3 to 6 days following intranasal inoculation of ureaplasmas and was resolved by 12 days. Rhinitis and otitis also occurred but did so less frequently than pneumonia. Organisms were localized within the alveoli in areas of inflammation. In comparison with newborn mice, 14-day-old mice were less susceptible to either colonization or disease.

Clearance of different strains of Mycoplasma pulmonis from the respiratory tract of C3H/HeN mice

Pathogen-free C3H/HeN mice were exposed by aerosol to Mycoplasma pulmonis PG34(ASH), UAB 5782C, M1, UAB T, or UAB CT, and clearance of mycoplasmas from the nasal passages, trachea, and lungs was determined during the first 72 h postinoculation (PI). There were differences among strains of mycoplasmas in physical removal of organisms and in killing by nonspecific factors in the nasal passages and trachea. The avirulent strain, PG34(ASH), was quickly removed from the nasal passages and trachea. Physical removal of the other mycoplasmal strains occurred slowly, with 60 to 89% of the radioactive label remaining in the nasal passages and trachea even after 72 h. There were significant differences in killing among mycoplasmal strains by nonspecific host mechanisms in the nasal passages, trachea, and lungs. Strain UAB T was quickly killed at all levels of the respiratory tract. Strains UAB 5782C and M1 were killed at all three sites by 2 to 4 h PI. The most virulent strain, UAB CT, was killed much more slowly than the other strains. However, there was no statistical difference in the relative numbers of mycoplasmas present in the lungs at 72 h PI among strains UAB CT, UAB 5782C, and M1. These studies showed that the different mycoplasmal strains were cleared from the respiratory tract by different mechanisms and suggest that the differences in virulence among the mycoplasma strains can be explained, in part, by the differences in elimination of the organisms from the respiratory tract by nonspecific host defense mechanisms.

Natural mycoplasmal infections in isolator-maintained LEW/Tru rats

For 4 years a colony of cesarean-derived, isolator-maintained LEW/Tru rats was evaluated for mycoplasmal infection by serology, culture and histopathology. Anti-mycoplasmal antibodies were detected by enzyme-linked immunosorbent assay (ELISA), and the colony eventually was found to have inapparent infections of Mycoplasma pulmonis and Mycoplasma arthritidis. Rats, naturally infected with M. pulmonis, remained consistently positive in the M. pulmonis ELISA after their initial seroconversion, and eventually developed clinical signs and lesions of respiratory and genital mycoplasmosis. M. pulmonis was apparently eliminated by serological testing and removal of infected rats. Rats naturally infected with M. arthritidis did not develop clinical or histologic evidence of mycoplasmal disease and their sera gave inconsistent results in the M. pulmonis ELISA, but eventually developed positive M. arthritidis ELISA responses. M. arthritidis was isolated from the genital tract, the intestinal tract, and Harderian gland. In contrast to M. pulmonis, removal of serologically positive animals was not sufficient for elimination of M. arthritidis from the colony.