Granzyme B+ CD4 T cells accumulate in the colon during chronic HIV-1 infection

Chronic HIV-1 infection results in the sustained disruption of gut homeostasis culminating in alterations in microbial communities (dysbiosis) and increased microbial translocation. Major questions remain on how interactions between translocating microbes and gut immune cells impact HIV-1-associated gut pathogenesis. We previously reported that in vitro exposure of human gut cells to enteric commensal bacteria upregulated the serine protease and cytotoxic marker Granzyme B (GZB) in CD4 T cells, and GZB expression was further increased in HIV-1-infected CD4 T cells. To determine if these in vitro findings extend in vivo, we evaluated the frequencies of GZB⁺ CD4 T cells in colon biopsies and peripheral blood of untreated, chronically infected people with HIV-1 (PWH). Colon and blood GZB⁺ CD4 T cells were found at significantly higher frequencies in PWH. Colon, but not blood, GZB⁺ CD4 T cell frequencies were associated with gut and systemic T cell activation and Prevotella species abundance. In vitro, commensal bacteria upregulated GZB more readily in gut versus blood or tonsil-derived CD4 T cells, particularly in inflammatory T helper 17 cells. Bacteria-induced GZB expression in gut CD4 T cells required the presence of accessory cells, the IL-2 pathway and in part, MHC Class II. Overall, we demonstrate that GZB⁺ CD4 T cells are prevalent in the colon during chronic HIV-1 infection and may emerge following interactions with translocated bacteria in an IL-2 and MHC Class II-dependent manner. Associations between GZB⁺ CD4 T cells, dysbiosis and T cell activation suggest that GZB⁺ CD4 T cells may contribute to gut HIV-1 pathogenesis.

Butyrate directly decreases human gut lamina propria CD4 T cell function through histone deacetylase (HDAC) inhibition and GPR43 signaling

An important function of the gut microbiome is the fermentation of non-digestible dietary fibers into short chain fatty acids (SCFAs). The three primary SCFAs: acetate, propionate, and butyrate, are key mediators of metabolism and immune cell function in the gut mucosa. We previously demonstrated that butyrate at high concentrations decreased human gut lamina propria (LP) CD4 T cell activation in response to enteric bacteria exposure in vitro. However, to date, the mechanism by which butyrate alters human gut LP CD4 T cell activation remains unknown. In this current study, we sought to better understand how exposure to SCFAs across a concentration range impacted human gut LP CD4 T cell function and activation. LP CD4 T cells were directly activated with T cell receptor (TCR) beads in vitro in the presence of a physiologic concentration range of each of the primary SCFAs. Exposure to butyrate potently inhibited CD4 T cell activation, proliferation, and cytokine (IFNγ, IL-17) production in a concentration dependent manner. Butyrate decreased the proliferation and cytokine production of T helper (Th) 1, Th17 and Th22 cells, with differences noted in the sensitivity of LP versus peripheral blood Th cells to butyrate's effects. Higher concentrations of propionate and acetate relative to butyrate were required to inhibit CD4 T cell activation and proliferation. Butyrate directly increased the acetylation of both unstimulated and TCR-stimulated CD4 T cells, and apicidin, a Class I histone deacetylase inhibitor, phenocopied butyrate's effects on CD4 T cell proliferation and activation. GPR43 agonism phenocopied butyrate's effect on CD4 T cell proliferation whereas a GPR109a agonist did not. Our findings indicate that butyrate decreases in vitro human gut LP CD4 T cell activation, proliferation, and inflammatory cytokine production more potently than other SCFAs, likely through butyrate's ability to increase histone acetylation, and potentially via signaling through GPR43. These findings have relevance in furthering our understanding of how perturbations of the gut microbiome alter local immune responses in the gut mucosa.

Gut Bacteria Induce Granzyme B Expression in Human Colonic ILC3s In Vitro in an IL-15-Dependent Manner

Group 3 innate lymphoid cells (ILC3s) in the gut mucosa have long been thought to be noncytotoxic lymphocytes that are critical for homeostasis of intestinal epithelial cells through secretion of IL-22. Recent work using human tonsillar cells demonstrated that ILC3s exposed to exogenous inflammatory cytokines for a long period of time acquired expression of granzyme B, suggesting that under pathological conditions ILC3s may become cytotoxic. We hypothesized that inflammation associated with bacterial exposure might trigger granzyme B expression in gut ILC3s. To test this, we exposed human colon lamina propria mononuclear cells to a panel of enteric bacteria. We found that the Gram-negative commensal and pathogenic bacteria induced granzyme B expression in a subset of ILC3s that were distinct from IL-22-producing ILC3s. A fraction of granzyme B⁺ ILC3s coexpressed the cytolytic protein perforin. Granzyme B expression was mediated, in part, by IL-15 produced upon exposure to bacteria. ILC3s coexpressing all three IL-15R subunits (IL15Rα/β/γ) increased following bacterial stimulation, potentially allowing for cis presentation of IL-15 during bacterial exposure. Additionally, a large frequency of colonic myeloid dendritic cells expressed IL-15Rα, implicating myeloid dendritic cells in trans presentation of IL-15 to ILC3s. Tonsillar ILC3s minimally expressed granzyme B when exposed to the same bacteria or to rIL-15. Overall, these data establish the novel, to our knowledge, finding that human colonic ILC3s can express granzyme B in response to a subset of enteric bacteria through a process mediated by IL-15. These observations raise new questions about the multifunctional role of human gut ILC3s.

Reduced immune-regulatory molecule expression on human colonic memory CD4 T cells in older adults

BACKGROUND

The etiology of the low-level chronic inflammatory state associated with aging is likely multifactorial, but a number of animal and human studies have implicated a functional decline of the gastrointestinal immune system as a potential driver. Gut tissue-resident memory T cells play critical roles in mediating protective immunity and in maintaining gut homeostasis, yet few studies have investigated the effect of aging on human gut T cell immunity. To determine if aging impacted CD4 T cell immunity in the human large intestine, we utilized multi-color flow cytometry to measure colonic lamina propria (LP) CD4 T cell frequencies and immune-modulatory marker expression in younger (mean ± SEM: 38 ± 1.5 yrs) and older (77 ± 1.6 yrs) adults. To determine cellular specificity, we evaluated colon LP CD8 T cell frequency and phenotype in the same donors. To probe tissue specificity, we evaluated the same panel of markers in peripheral blood (PB) CD4 T cells in a separate cohort of similarly aged persons.

RESULTS

Frequencies of colonic CD4 T cells as a fraction of total LP mononuclear cells were higher in older persons whereas absolute numbers of colonic LP CD4 T cells per gram of tissue were similar in both age groups. LP CD4 T cells from older versus younger persons exhibited reduced CTLA-4, PD-1 and Ki67 expression. Levels of Bcl-2, CD57, CD25 and percentages of activated CD38+HLA-DR+ CD4 T cells were similar in both age groups. In memory PB CD4 T cells, older age was only associated with increased CD57 expression. Significant age effects for LP CD8 T cells were only observed for CTLA-4 expression, with lower levels of expression observed on cells from older adults.

CONCLUSIONS

Greater age was associated with reduced expression of the co-inhibitory receptors CTLA-4 and PD-1 on LP CD4 T cells. Colonic LP CD8 T cells from older persons also displayed reduced CTLA-4 expression. These age-associated profiles were not observed in older PB memory CD4 T cells. The decline in co-inhibitory receptor expression on colonic LP T cells may contribute to local and systemic inflammation via a reduced ability to limit ongoing T cell responses to enteric microbial challenge.

ras gene mutations are absent in NMU-induced mammary carcinomas from aging rats

Carcinoma induction in the rat mammary carcinogenesis model is age dependent. In this study, mammary cancer susceptibility and ras gene activation were investigated in rats exposed to N:-methyl-N:-nitrosourea (NMU) at 2, 6, 8 and 15 months. Animals were resistant to NMU-induced mammary tumor development when exposed at 6 and 8 months of age, whereas a significant number of mammary carcinomas developed in animals exposed to NMU at 2 and 15 months of age. G35-->A35 activating mutations in the Harvey ras gene were found only in mammary carcinomas from rats exposed to NMU at 2 months of age, but not in tumors that developed in animals exposed to NMU at 15 months of age. No G35-->A35 activating mutations were present in the Kirsten ras gene of any of the mammary tumors. Additional analysis of exons 1 and 2 of the Harvey ras gene from mammary carcinomas that developed in animals exposed to NMU at 15 months of age did not reveal any other activating mutations in this gene. In mammary carcinomas from animals exposed to NMU at 2 months of age, the frequency of mammary carcinomas with mutations in the Harvey ras gene was independent of the time from which the tumor first appeared. Therefore, age at the time of carcinogen exposure plays a critical role in both breast cancer susceptibility and the molecular events that contribute to mammary carcinoma development.

Surgeon perspectives on surgical options for early-stage breast cancer

To evaluate the practice patterns of general and plastic surgeons regarding patients with early-stage breast cancer, all general and plastic surgeons in Quebec and Maryland were mailed self-administered questionnaires evaluating surgeon demographics, practice patterns, treatment preferences, and satisfaction with the results of lumpectomy and radiation therapy or breast reconstruction. Response rates of 38.3 percent and 26.7 percent were obtained for general surgeons in Quebec and Maryland, respectively. The ratio of reported mastectomies to lumpectomies was 1:2 in Maryland and 1:5 in Quebec. All general surgeons considered lumpectomy an important option. Ninety percent of Maryland surgeons versus 44 percent of Quebec surgeons considered mastectomy important. A total of 53.6 percent versus 24.9 percent of general surgeons in Maryland and Quebec, respectively, considered delayed reconstruction an important option. Additionally, 81.3 percent of Maryland surgeons considered immediate reconstruction important, and 79.6 percent discussed it with all stage I or II patients. More than 75 percent of Quebec general surgeons reported discussing immediate or delayed reconstruction with < or =50 percent of these women. Response rates of 53.6 percent and 48.8 percent were obtained for plastic surgeons in Quebec and Maryland, respectively. In one year Quebec plastic surgeons reported that they performed less than half the number of reconstructions performed by Maryland plastic surgeons (7.2 versus 17.3). In Quebec, 82.3 percent of surgeons reported that they frequently discuss delayed reconstruction, 25.1 percent immediate, 62.5 percent pedicled TRAM, and 51.7 percent nonautogenous options. In Maryland, 74.3 percent of plastic surgeons frequently discuss delayed reconstruction, 95.7 percent immediate, 89.9 percent pedicled TRAM, and 85.9 percent nonautogenous options. For women with early-stage breast cancer, regional variations exist in the surgical options discussed and provided.

Surgical options for the early-stage breast cancer: factors associated with patient choice and postoperative quality of life

Patients with early-stage breast cancer have three surgical options: lumpectomy with radiotherapy, mastectomy alone, and mastectomy with breast reconstruction. Our objective was to compare women in these three groups with respect to demographics, preoperative counseling, postoperative body image, and quality of life. Women having undergone surgery for stage 1 or 2 breast cancer between 1990 and 1995 were selected by random sampling of hospital tumor registries and were mailed a self-administered questionnaire, which included the Medical Outcomes Survey Short Form 36. Patients were stratified into three mutually exclusive groups: lumpectomy with axillary node dissection and radiotherapy, modified radical mastectomy, and modified radical mastectomy with breast reconstruction. In total, 267 of 525 surveys were returned (50.9 percent). Compared with mastectomy patients, breast reconstruction patients were younger (p < 0.001), better educated (p = 0.001), and more likely Caucasian (p = 0.02). Among mastectomy patients, 54.9 percent recalled that lumpectomy had been discussed preoperatively and 39.7 percent recalled discussion of breast reconstruction. Post-operative comfort with appearance was significantly lower for mastectomy patients. The relationship between type of surgery and postoperative quality of life varied with age. Under 55, quality of life was lowest for mastectomy patients on all but two Medical Outcomes Survey Short Form 36 subscales. Over 55, quality of life was lowest for lumpectomy patients on all subscales (p < 0.05 for all subscales except social functioning and role-emotional). Treatment choice may be related to age, race, education, and preoperative counseling. Whereas the effect of breast cancer on a woman's life is complex and individual, the type of surgery performed is a significant variable, whose impact may be related to patient age.

Harvey ras results in a higher frequency of mammary carcinomas than Kirsten ras after direct retroviral transfer into the rat mammary gland

Exclusive activation of either the Harvey-, Kirsten-, or N-ras gene is often found in human and rodent cancers, although the mechanisms responsible for tissue-specific ras gene activation are poorly understood. In this study, the contribution of ras gene expression and Ras protein activity to the tissue-specificity of ras gene activation was investigated using the rat mammary carcinogenesis model where ras activation, when it occurs, is exclusively in the Harvey ras gene. Differential ras gene expression was examined in mammary tissue from virgin, pregnant, and lactating rats. Harvey ras expression was 1.5-2-fold higher than Kirsten ras or N-ras at each adult stage of development, with the highest ras levels expressed during pregnancy. The modest difference in total mRNA expression found between the independent members of the ras gene family is unlikely to fully account for the exclusive tissue-specificity of Harvey ras activation observed in rat mammary carcinogenesis. Thus, the role of Ras protein specificity was studied by infecting the mammary gland of virgin rats in situ with replication-defective retroviral vectors expressing either the activated or wild-type forms of Harvey- or Kirsten-ras. A 7-14-fold higher number of mammary carcinomas was observed after infection with vectors expressing the G35 to A activated Harvey ras gene product compared with those expressing G35 to A activated Kirsten ras. Mammary carcinomas also developed from infusion of vectors expressing wild-type Harvey ras, but not wild-type Kirsten ras. These data suggest the importance of the Ras protein itself in determining the specificity of the highly homologous Ras family members in organ-specific carcinogenesis.

Induction of apoptosis by organotin compounds in vitro: neuronal protection with antisense oligonucleotides directed against stannin

Immortalized cell lines and primary neuronal cultures were used to characterize the selective toxicity of trimethyltin (TMT),triethyltin (TET) and tributyltin (TBT). TBT and TET were cytotoxic at similar concentrations in the immortalized cell lines tested; the 50% toxic concentration (TC50) was 1 to 11 microM. In contrast, immortalized cell lines varied considerably in their sensitivity to TMT, with sensitive cell lines (neuroblastomas, T-, B-cell lines) showing TC50 values of 2 to 8 microM, whereas insensitive cells (NIH-3T3 fibroblast, HTB-14 glioma, TC-7 kidney cells) had TC 50 values > 100 microM. Primary neuronal cell cultures were very sensitive to organotins (TC50 values, 1-10nM), and showed patterns of selective toxicity with respect to neuronal and glial cells. Because organotin toxicity evolves over 24 to 48 hr. we determined whether these compounds induced apoptosis in primary cultures. TMT increased (P < .05) the fraction of apoptotic cells 6 and 12 hr after treatment with TMT at TC50 concentrations. Prior studies suggested that a protein, stannin, was localized in cells sensitive to organotins. Stannin was expressed in several TMT-sensitive cell lines (PC12, T, B cells) and in primary neurons in culture. Stannin was absent in the resistant HTB-14 glioma cell line. The role of stannin in mediating TMT toxicity in primary cultures was investigated by blocking stannin expression with specific antisense oligonucleotides. Treatment of primary cultures with antisense oligonucleotides for 48 hr before and during TMT treatment significantly protected neurons from the neurotoxic and apoptotic effects of TMT. This effect was not observed with scrambled oligonucleotide controls. Thus, TMT may induce apoptosis in sensitive cells, which is partly mediated by stannin. Based on the available data we conclude that stannin expression is necessary, but not sufficient for TMT toxicity.

Experimental laparoscopic aortobifemoral bypass

The goal of the present study is to develop a technique for laparoscopic aortobifemoral bypass. Piglets weighing between 60 and 78 kg were anesthetized with halothane. The lateral retroperitoneal approach was preferred to the more familiar anterior transperitoneal approach and was successfully completed in 19 piglets. The piglets were placed in the right lateral decubitus position. The first port (2 cm) was inserted halfway between the tip of the 12th rib and the iliac crest. Four other trocars were placed in the retroperitoneum after balloon inflation had allowed creation of a space which permitted visualization of the aorta from the left renal artery down to the aorto-iliac junction. After evacuation of the retropneumoperitoneum, the cavity was maintained using an abdominal lift device and a retractor. Using this approach, we performed four aorto-bifemoral bypasses (end-to-end aortic anastomosis) after conventional intravenous heparinization (100 IU/kg) in less than 4 h. Blood loss did not exceed 250 ml and the hematocrit remained stable. Postmortem evaluation of the grafts revealed they were positioned as in a conventional bypass, their limbs having followed in the created retroperitoneal tunnels along the path of the native arteries. No mortality occurred before sacrifice of the animals. We believe that this first performed series of totally retroperitoneal laparoscopic aortobifemoral bypasses in the porcine model is useful in preparation for human application due to the anatomical similarities in the periaortic region.

Transcriptional regulatory and response mapping of the rat Ha-ras upstream sequence using primary mammary epithelial cells

The rat Ha-ras upstream sequence (-2876 to +986 bp relative to the most 5' transcriptional start site) was transcriptionally mapped at a gross level. Ha-ras upstream sequence and 5' unidirectional deletion reporter constructs were transfected via particle bombardment into primary cultures of rat mammary epithelial cells. Analyses of Ha-ras reporter expression show that a fragment extending from -2876 to -2110 bp contains a positive regulatory sequence. The majority of Ha-ras expression is attributed to this sequence, since its deletion results in a 4-fold decrease in expression. The Ha-ras gene was also assessed for autoregulation using similar co-transfection experiments. Wild-type and activated (codon 12 G-->A transition) Ha-ras expression vectors, transcriptionally driven by Ha-ras upstream sequence, were co-transfected with Ha-ras upstream sequence deletion reporter constructs. The activated Ha-ras gene product induced its own transcription 2-fold, targeting the regulatory region between -2119 and -313 bp.

Transient promoter activity in primary rat mammary epithelial cells evaluated using particle bombardment gene transfer

The relative strengths of several commonly used viral promoters in primary cultures of rat mammary epithelial cells were studied using a particle bombardment gene transfer method. NIH 3T3 cells were also examined as a representative cell line. Initially, the conditions necessary for efficient gene transfer using particle bombardment were determined. Discharge voltage for particle bombardment was evaluated to maximize the levels of gene expression and cell viability. After transfection, transgene expression decreased over a 5-day period in both mammary cells and NIH 3T3 cells. Particle bombardment gene transfer was at least fivefold more efficient than lipofection, calcium phosphate co-precipitation, or electroporation. The activity of five viral enhancer/promoters was compared using a luciferase gene assay system. The relative promoter strengths in mammary cells were determined to be: RSV approximately CMV approximately SV40 > MLV > MMTV. Tissue-specific activity of the MMTV-LTR was demonstrated, although this promoter conferred the lowest expression level among the promoters tested.

Alterations in mitogen-induced calcium mobilization and intracellular free calcium produced by 7,12-dimethylbenz(a)anthracene in the Jurkat human T cell line

The purpose of these studies was to assess the effects of 7,12-dimethylbenz(a)anthracene (DMBA), an immunosuppressive polycyclic aromatic hydrocarbon (PAH), on Ca+2 mobilization induced by phytohemagglutinin (PHA) in the Jurkat human T cell line. Intracellular levels of free cytosolic Ca+2 were examined by flow cytometry using Indo-1 loaded cells. At doses of 3-30 microM, DMBA was found to produce a dose and time-dependent inhibition of Ca+2 mobilization in Jurkat following in vitro exposure. The decrease in Ca+2 mobilization was correlated with an increase in baseline levels of cytoplasmic free Ca+2. Two non-immunosuppressive PAH, benzo(e)pyrene and anthracene, failed to inhibit PHA-induced Ca+2 mobilization or alter baseline levels of free Ca+2. These results suggest that DMBA may produce immunosuppression by inhibiting Ca+2 mobilization or by altering Ca+2 homeostasis in activated T cells.

Bioequivalence of carbamazepine chewable and conventional tablets: single-dose and steady-state studies

Single-dose and steady-state studies were carried out on separate occasions to examine the bioequivalence of the newly formulated carbamazepine chewable tablet. In the single-dose study, the plasma levels resulting from 2 X 200-mg conventional tablets (CT), 4 X 100-mg chewable tablets swallowed whole (SW), and 4 X 100-mg chewable tablets chewed before swallowing (CHEW) were compared. A randomized 3 X 3 Latin-square design balanced for residual effects, with a 3-week washout period, was used (n = 6). Plasma samples were analyzed by a specific GC method for carbamazepine. The following parameters were used for evaluation: AUC, Cmax, tmax, and t1/2. None of the parameters were significantly different except Cmax and t1/2 values for CHEW and CT. The Cmax was 25% higher and t1/2 was 11% shorter for CHEW than CT. The impact of differences in the peak plasma levels at steady state were examined by pharmacokinetic projection (400 mg b.i.d.) based on the single-dose data and with simulated induction equal to a 50% reduction in t1/2. The projected steady-state CT and CHEW plasma concentrations were similar, with a difference of only 4%. The results demonstrate the bioequivalence of the dosage forms with respect to the extent of absorption, and similar steady-state concentrations of carbamazepine in plasma can be expected. To test the conclusion from the projected study, a separate bioequivalence study to compare CHEW relative to CT was performed at steady state in normal volunteers (200 mg b.i.d.).(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of a solid-phase immunofluorescence assay for detection of antibodies to Legionella pneumophila

A semiautomated solid-phase immunofluorescence technique (FIAX) was compared with the standard indirect immunofluorescence assay (IFA) for the determination of antibody levels to Legionella pneumophila serogroup 1 in paired human serum samples. The FIAX method was in agreement with the IFA test for 91.8% of the serum pairs but gave evidence of a recent Legionella infection significantly fewer times than did the IFA. These results suggest that the FIAX technique may eventually be a useful alternative test for measuring Legionella antibodies. However, further study will be required to determine its efficacy in providing a serodiagnosis of legionellosis.

Aminoglutethimide bioavailability, pharmacokinetics, and binding to blood constituents

The bioavailability of aminoglutethimide tablets was examined using a spectrophotometric assay. For six subjects receiving 500 mg of aminoglutethimide as an oral solution, the average peak concentration was 6.2 micrograms/ml with a median time of 0.8 hr. The corresponding average peak concentration for tablet administration was 5.9 micrograms/ml with a median time of 1.5 hr. Average values for the area under the curve (AUC) extrapolated to infinity were 89.0 and 96.8 micrograms hr/ml for the solution and tablets, respectively. The tablets had a 9% larger mean for the AUC than the solution and a 5% lower value for the mean maximum concentration. The bioavailability of the tablets is considered equal to that of oral solution. Data for individual concentration versus time curves were treated by nonlinear least-squares curve fitting. A two-compartment model with first-order absorption gave an acceptable fit for most data sets, but the individual absorption rate coefficients were not reliably determined. Values were estimated for plasma clearance, renal clearance, and volume of distribution. The distribution of aminoglutethimide between plasma and cells of human blood was examined in vitro; the drug concentration in cells was 1.4-1.7 times the concentration in plasma. The binding of aminoglutethimide to plasma proteins of human blood was measured by equilibrium dialysis at starting concentrations of 5 and 10 micrograms/ml. The binding ranged from 21.3 to 25.0% without concentration dependence.

Indigenous nasopharyngeal, auditory canal, and middle ear bacterial flora of gerbils: animal model for otitis media

The indigenous microbial flora of the middle ear cavity of Mongolian gerbils, Meriones unguiculatus, was isolated, characterized, and identified, showing it to be sparse and transitory. Organisms, when found in the middle ear cavity, were most likely to be Staphylococcus epidermidis-like organisms. Cerumen from the external auditory canal of these animals yielded mostly staphylococci, coryneforms, and other gram-positive rods, including some anaerobic species. The nasopharynx supported a flora consisting mainly of staphylococci, lactobacilli, and coryneforms, with a smaller incidence and numbers of many other species. No mycoplasmas were cultured or seen in scanning electron microscope studies. None of the major pathogens of human otitis media were found; therefore, Mongolian gerbils are microbiologically acceptable candidates as a model for induced otitis media, using organisms isolated from human otitic infections.

Legionella micdadei (Pittsburgh pneumonia agent): direct fluoresent-antibody examination of infected human lung tissue and characterization of clinical isolates

Legionella micdadei (Pittsburgh pneumonia agent) was identified by direct fluorescent-antibody (DFA) examination of lung tissue in six of seven persons diagnosed previously as having L. micdadei pneumonia only by histopathology and in four persons who also had positive cultures of the organism. No cross-reactions occurred with monospecific DFA conjugates prepared against Legionella pneumophila serogroups 1 to 6, Legionella bozemanii, Legionella dumoffii, and Legionella gormanii. One person had L. pneumophila serogroup 6 identified by DFA examination of lung tissue and subsequent culture of stored pulmonary secretions. Characterization of the four strains of L. micdadei revealed specific DFA reactions, bacteriological behavior, and cellular fatty acid composition that allow identification of the organism. DFA testing appears to be a sensitive method for identifying L. micdadei prescent in human lung tissue or cultured on artificial media.

Laboratory studies of disinfectants against Legionella pneumophila

Legionella pneumophila suspended in tap water was exposed to biocides recommended for inhibiting biological growth in cooling towers and evaporative condensers of air-conditioning systems. Chlorine, 2,2-dibromo-3-nitrilopropionamide, and a compound containing didecyldimethylammonium chloride and isopropanol were effective in destroying concentratiois of 10(5) to 10(6) viable cells per ml. Formulations consisting of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one, disodium ethylene bis(thiocarbamate) and sodium dimethyl dithiocarbamate, and a phenolic with pentachlorophenate and sodium salts of other chlorophenols were less effective.

Effects of aspirin on 14C-pirprofen disposition in rats

The effects of aspirin on 14C-pirprofen disposition in the rat were studied. An oral 60-mg/kg dose of aspirin significantly reduced plasma radioactivity during the 1--8-hr interval after an intravenous 5-mg/kg injection of 14C-pirprofen. The aspirin-treated group had only 69% as much area under the radioactivity curve as the control group. The radioactive material in plasma consisted almost entirely of 14C-pirprofen, as shown by GLC. The plasma clearance of 14C-pirprofen was 7.4 ml/hr for the aspirin-treated group and 5.1 ml/hr for the control group, while the volumes of distribution were 0.32 and 0.20 liter/kg, respectively. The apparent elimination half-life was unchanged at 5.9 hr. 14C-Pirprofen was approximately 98.6% bound to plasma proteins, and the binding decreased to an average of 97.2% in the presence of salicylate. Binding to blood cellular constituents was insignificant. Rats give 14C-pirprofen by intravenous injection without aspirin secreted 36.0--42.8% of the dose radioactivity into bile during 4 hr while a comparable group given 60 mg of aspirin/kg secreted 46.4--70.8%. TLC and GLC demonstrated that the radioactivity in rat bile was 80--90% conjugated 14C-pirprofen. The increased radioactive material secretion into bile was compensated in the intact rat by reabsorption, since the total radioactive material excreted in urine was not changed by aspirin administration.