IgG antibody and delayed-type hypersensitivity responses in nude mice grafted with thymic epithelium.

This study compared the ability of foetal thymic epithelium depleted of lymphocytes and dendritic cells, by low temperature or deoxyguanosine (dGuo) treatment in organ culture, to reconstitute T-cell function in nude mice. It is shown that renal capsule grafts of either type could promote the development of functional T lymphocytes in the periphery, as judged by in vivo assays. Both syngeneic and allogeneic thymic epithelium endowed nude mice with the capacity to mount IgG antibody and delayed-type hypersensitivity (DTH) responses to the T-dependent antigen ovalbumin (OVA). Functional reconstitution was accompanied by the appearance of Thy-1-bearing cells in the spleens of thymic grafted nude mice. The results from allogeneically grafted recipients show that a substantial population of peripheral T cells was present that collaborated with B cells and other antigen-presenting cells (APC) which do not express major histocompatibility complex (MHC) molecules of the thymus donor haplotype.     

Interferon Sensitivity of Venezuelan Equine Encephalomyelitis Virus

Two strains of Venezuelan equine encephalomyelitis virus, which differ in virulence for mice, have been studied for their production of and sensitivity to chick and mouse interferon. Little interferon was produced by chick cells in response to the virulent Trinidad strain or the attenuated TC-83 strain without either aging or priming the cultures. Consistent differences in the production of chick interferon were not found between the two strains. Plaque variants of the Trinidad strain produced higher titers of mouse interferon than the TC-83 strain in both primed and control L-cell cultures. The TC-83 strain was found to be more sensitive than the Trinidad strain to the inhibitory effects of interferon. The greater sensitivity of the TC-83 strain was observed at both high and low multiplicities and for both chick and mouse interferons. These results are consistent with the hypothesis that interferon sensitivity may have a role as a determinant of virulence in some virus-host systems.     

Minnesota Multiphasic Personality Inventory (MMPI) cluster groups among chronically ill patients: Relationship to illness adjustment and treatment outcome

Cluster analysis of the MMPI has been utilized widely in the chronic low back pain literature to try to identify reliable patient subtypes predictive of treatment outcome. We extended this methodology to patients with heterogeneous chronic medical conditions by replicating prototypic MMPI cluster group profiles and by relating cluster groups to clinical baseline and outcome data. Subjects were two independent samples (n=254 and n=263) of chronically ill patients admitted to an inpatient medicine/psychiatry unit. Using a four-cluster solution, similar cluster profile groups were replicated in both samples. Consistent differences emerged between cluster groups on functional impairment, psychiatric diagnoses, depression, and psychosomatic symptoms. Cluster group membership also predicted changes in functional impairment and depression six months after treatment. Results are discussed in terms of similarities between chronic low back pain and chronic illness and tailoring treatment to different patient types.This research was supported in part by a grant from the Henry J. Kaiser Family Foundation.     

Comparative histopathology of lesions produced by Actinomyces israelii, Actinomyces naeslundii, and Actinomyces viscosus in mice.

The histopathologic features of experimental actinomycotic lesions produced in mice by Actinomyces israelii, Actinomyces naeslundii, and Actinomyces viscosus were examined. In lesions caused by A israelii the outer edge of the bacterial granule exhibited an eosinophilic fringe with no evidence of penetration of polymorphonuclear leukocytes (PMNs) into the bacterial granule. Chronic lesions after 6 weeks contained lobulated advancing fronts as well as areas of resolution showing heavy penetration by phagocytic cells. The number of macrophages and plasma cells in these lesions increased with time. In contrast, lesions caused by A viscosus and A naeslundii showed cellular evidence of resolution during the early stages of the infection (3-6 weeks). The bacterial core was readily penetrated and fragmented by PMNs in early A viscosus lesions. In lesions caused by A naeslundii there was less penetration of the central core by PMNs, and the bacterial granule tended to retain its structural integrity. Elongated crystals of hyaloid material appeared in lesions caused by all species. These protein-rich bodies appeared to be associated with resolving areas of the lesions. The observed contrast in the histopathologic appearance of actinomycotic lesions caused by A israelii, A naeslundii, and A viscosus is suggestive of important differences in the immune response of the host to infections caused by these three species.     

Expression of silencer of death domains and death-receptor-3 in normal human kidney and in rejecting renal transplants

We have previously reported the pattern of cellular expression of tumor necrosis factor receptors (TNFR) in human kidney and their altered expression in transplant rejection. We have extended our studies to examine the expression of Silencer of Death Domains (SODD), a protein that binds to the cytoplasmic portion of TNFR1 to inhibit signaling in the absence of ligand. In normal human kidney SODD is expressed in glomerular endothelial cells where it colocalizes with TNFR1. During acute rejection both SODD and TNFR1 are lost from glomeruli, but we found strong expression of SODD on the luminal surface of tubular epithelial cells. This occurs in the absence of detectable TNFR1 expression, suggesting that SODD could interact with other proteins at these sites. Several other members of the TNF superfamily, including Fas and death receptors (DR)-3, -4, and -5, also contain intracellular death domains, but SODD only interacts with the death domain of DR3. We therefore studied the expression of DR3 in human kidney, and report that this death receptor is up-regulated in renal tubular epithelial cells and endothelial cells of some interlobular arteries, in parallel with SODD, during acute transplant rejection. In less severe rejection episodes, DR3 and SODD were more focally induced, generally at sites of mononuclear cell infiltrates. In ischemic allografts, eg, with acute tubular necrosis but no cellular rejection, DR3 was induced on tubular epithelial cells and on glomerular endothelial cells. These data confirm that TNF receptor family members are expressed in a regulated manner during renal transplant rejection, and identify DR3 as a potential inducible mediator of tubular inflammation and injury.     

Presynaptic depolarization in myelinated vagal afferent fibres terminating in the nucleus of the tractus solitarius in the cat

The presynaptic influences that act on terminals of slowly adapting lung stretch receptor afferents and aortic baroreceptor afferents within the nucleus of the solitary tract were assessed using intracellular recording and antidromic stimulation techniques.Central respiratory influences on the axcitability of lung stretch receptor terminals were observed in 29% (4 of 14) of measurements. These were confirmed in intracellular recordings where membrane depolarizations in synchrony with phrenic nerve discharge were seen in 17% (4 of 24) of fibres. In three cases membrane depolarization also occurred synchronously with artificial lung inflation.Neither tests of excitability nor intracellular recording revealed any evidence for equivalent presynaptic influences on 16 myelinated aortic baroreceptor terminals.Stimulation of the superior laryngeal nerve evoked depolarizations in 50% (7 of 14) of lung stretch receptor terminals. These took the form of complex waves of depolarization with both short (3–8 ms) and long latency (27–35 ms) components. The amplitude of the long latency response increased during the period of phrenic nerve discharge, i.e. during central inspiration.These effects are discussed in relation to the central respiratory influences on both respiratory and cardiovascular reflexes.     

Blinded, two-laboratory comparative analysis of Escherichia coli heat-stable enterotoxin production by using monoclonal antibody enzyme-linked immunosorbent assay, radioimmunoassay, suckling mouse assay, and gene probes

Heat-stable enterotoxin (ST)-producing enterotoxigenic Escherichia coli (ETEC) can be identified by a variety of assays, including the suckling mouse assay (SMA), radioimmunoassay (RIA), polyclonal or monoclonal antibody enzyme-linked immunosorbent assay (ELISA), and DNA hybridization with STh and STp gene probes. To compare the sensitivity and reliability of these assays, 100 coded ETEC and non-ETEC isolates were blindly tested in two independent laboratories. SMA, RIA, and monoclonal ELISA were performed in Cincinnati, Ohio, while gene probe analysis was performed in Baltimore, Md. The method of storage of organisms had a profound effect on the stability of plasmids in certain strains. Hybridization experiments to determine the presence or absence of the enterotoxin gene showed that strains stored on Dorset egg medium at room temperature better retained their plasmids than strains stored frozen in skim milk. Forty-four of the 100 organisms obtained from the skim milk stock were found to produce STa in liquid culture by the RIA, SMA, and monoclonal ELISA (100% agreement). However, 50 of 54 of the strains stored on Dorset egg medium which were originally classified as STa+ or ST+ LT+ (positive for both heat-stable and heat-labile [LT] enterotoxins) were found to produce STa and retain the plasmid by each of these assays. Three additional strains were found which harbored the plasmid but did not elaborate STa by any of the assays (3% discrepancy). The monoclonal antibody ELISA appears to be highly reliable for determination of STa production by ETEC and can be easily scored visually even by untrained personnel. Furthermore, when this STa assay is coupled with a polyclonal antibody assay, it is possible to predict the genotype of STh- and STp-producing organisms.     

The minimum inhibitory concentration of kitasamycin, tylosin and tiamulin for Mycoplasma gallisepticum and their protective effect on infected chicks

The minimum inhibitory concentration (m.i.c.) of kitasamycin, tylosin and tiamulin for Mycoplasma gallisepticum (Mg) were compared with 10(6), 10(4), and 10(2) CFU/ml of the organisms with the drug incorporated in mycoplasma agar. The lowest m.i.c. was obtained with tiamulin and the highest with kitasamycin and, in general, the m.i.c.'s were directly influenced by the concentration of mycoplasmas. Chick embryos at 19 days of incubation were infected with Mg and the hatched infected chicks were used for comparing the protective effect of the three drugs. They were given in the drinking water when the chicks were 2, 3 and 4 days of age. Weight gains for the infected treated birds were similar for all three drugs; they were significantly lower than for those of uninfected chicks and significantly higher than for those of untreated infected chicks. However Mg could be isolated from a high proportion of chicks in the infected treated and untreated groups at 32 days of age.     

Cytokine gene polymorphisms moderate illness severity in infants with respiratory syncytial virus infection

Illness severity and frequency of complications in infants with respiratory syncytial virus (RSV) infection may be influenced by the local elaboration of cytokines. Cytokine gene polymorphisms moderate severity of illness in various inflammatory and infectious diseases. We performed cytokine genotyping on 77 infants hospitalized with confirmed RSV infection to determine whether specific cytokine gene polymorphisms are associated with illness severity or complications. DNA was extracted from buccal brushings and assayed for tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, interleukin (IL)-6 and IL-10, and transforming growth factor (TGF)-beta1 genotypes using polymerase chain reaction-sequence-specific primer technology. Clinical outcomes consisted of severity scores of lower respiratory illness, blood oxygen saturation, lengths of oxygen supplementation, and intensive care unit (ICU) and hospital stays, and the presence or absence of pneumonia and otitis media. IFN-gamma genotype was related to severity of lower respiratory illness, duration of ICU stay, and frequency of otitis media. Additionally, IL-6 genotype was related to the length of oxygen (O(2)) supplementation and hospital stay, IL-10 genotype to the frequency of pneumonia, and TGF-beta1 genotype to O(2) saturations at presentation. There were no associations between TNF-alpha genotype and any of the outcome parameters. These results demonstrate that certain cytokine gene polymorphisms contribute to illness severity and complications during RSV infection in infants. If future prospective studies confirm these observations, cytokine genotyping may be a useful tool for identifying "at risk" infants who may benefit from the selective use of preventive or early intervention treatments for RSV.