Differential roles of IL-1 and TNF-alpha on graft-versus-host disease and graft versus leukemia

We demonstrate an increase in graft-versus-host disease (GVHD) after experimental bone marrow transplant (BMT) when cyclophosphamide (Cy) is added to an otherwise well-tolerated dose (900 cGy) of total body irradiation (TBI). Donor T cell expansion on day +13 was increased after conditioning with Cy/TBI compared with Cy or TBI alone, although cytotoxic T lymphocyte (CTL) function was not altered. Histological analysis of the gastrointestinal tract demonstrated synergistic damage by Cy/TBI and allogeneic donor cells, which permitted increased translocation of LPS into the systemic circulation. TNF-alpha and IL-1 production in response to LPS was increased in BMT recipients after Cy/TBI conditioning. Neutralization of IL-1 significantly reduced serum LPS levels and GVHD mortality, but it did not affect donor CTL activity. By contrast, neutralization of TNF-alpha did not prevent GVHD mortality but did impair CTL activity after BMT. When P815 leukemia cells were added to the bone marrow inoculum, allogeneic BMT recipients given the TNF-alpha inhibitor relapsed at a significantly faster rate than those given the IL-1 inhibitor. To confirm that the role of TNF-alpha in graft versus leukemia (GVL) was due to effects on donor T cells, cohorts of animals were transplanted with T cells from either wild-type mice or p55 TNF-alpha receptor-deficient mice. Recipients of TNF-alpha p55 receptor-deficient T cells demonstrated a significant impairment in donor CTL activity after BMT and an increased rate of leukemic relapse compared with recipients of wild-type T cells. These data highlight the importance of conditioning in GVHD pathophysiology, and demonstrate that TNF-alpha is critical to GVL mediated by donor T cells, whereas IL-1 is not.

Keratinocyte growth factor separates graft-versus-leukemia effects from graft-versus-host disease

The major obstacles to successful outcome after allogeneic bone marrow transplantation (BMT) for leukemia remain graft-versus-host disease (GVHD) and leukemic relapse. Improved survival after BMT therefore requires more effective GVHD prophylaxis that does not impair graft-versus-leukemia (GVL) effects. We studied the administration of human recombinant keratinocyte growth factor (KGF) in a well- characterized murine BMT model for its effects on GVHD. KGF administration from day -3 to +7 significantly reduced GVHD mortality and the severity of GVHD in the gastrointestinal (GI) tract, reducing serum lipopolysaccharide (LPS) and tumor necrosis factor (TNF)alpha levels, but preserving donor T-cell responses (cytotoxic T lymphocyte [CTL] activity, proliferation, and interleukin [IL]-2 production) to host antigens. When mice received lethal doses of P815 leukemia cells at the time of BMT, KGF treatment significantly decreased acute GVHD compared with control-treated allogeneic mice and resulted in a significantly improved leukemia-free survival (42% v 4%, P <.001). KGF administration thus offers a novel approach to the separation of GVL effects from GVHD.

Short-term regulation of bile acid uptake by microfilament-dependent translocation of rat ntcp to the plasma membrane

The Na+-taurocholate cotransport polypeptide (ntcp) is the primary transporter for the uptake of bile acids in the liver. The second messenger adenosine 3':5'-cyclic monophosphate (cAMP) rapidly increases ntcp protein concentration in the plasma membrane, yet the mechanism is unknown. To investigate this, HepG2 cells were transiently transfected with a carboxy-terminal-tagged green fluorescence protein (GFP) conjugate of ntcp, and then examined by confocal video microscopy. Transporter activity was directly assayed with 3H-taurocholic acid (TC) scintigraphy. ntcp-GFP targeted to the plasma membrane in transfected cells, and the conjugate protein transported 3H-TC as effectively as unmodified rat ntcp. Stimulation of ntcp-GFP cells with cAMP increased GFP fluorescence in the plasma membrane by 40% (P <.0001) within 2.5 minutes and by 55% within 10 minutes. Similarly, cAMP increased transport of bile acids by 30%. Cytochalasin D, an inhibitor of microfilaments, did not prevent ntcp-GFP from targeting to the plasma membrane, but completely abolished the increase in GFP fluorescence seen in response to cAMP. In contrast, the microtubule inhibitor, nocodazole, prevented development of membrane fluorescence in 48 (96%) of 50 cells. Cells regained plasma membrane fluorescence within 2 hours after nocodazole removal. These findings suggest that targeting of ntcp to the plasma membrane consists of 2 steps: 1) delivery of ntcp to the region of the plasma membrane via microtubules; and 2) insertion of ntcp into the plasma membrane, in a microfilament- and cAMP-sensitive fashion.

Hepatic regulation of platelet-activating factor acetylhydrolase and lecithin:cholesterol acyltransferase biliary and plasma output in rats exposed to bacterial lipopolysaccharide

Normal rat bile contains secretory platelet-activating factor acetylhydrolase (PAF-AH), the enzyme capable of hydrolyzing the inflammatory mediator platelet-activating factor (PAF), and phospholipids containing oxidized truncated fatty acids. Because lecithin:cholesterol acyltransferase (LCAT) possesses intrinsic PAF-AH-like activity, it also may represent a potential anti-inflammatory enzyme. The behavior of PAF-AH and LCAT in hepatobiliary inflammatory responses in vivo has not been characterized. We therefore investigated the biliary and plasma secretion and pharmacological characteristics of these enzymes in rats subjected to intraportal bacterial endotoxin exposure (lipopolysaccharide [LPS], Escherichia coli, 055:B5). Portal vein LPS infusion (1 mg/kg, bolus) resulted in a maximal 4- to 5-fold increase in bile PAF-AH-specific activity with a gradual decline to baseline by 18 hours. Biliary PAF-AH hydrolyzed also the truncated sn-2-succinoyl and sn-2-glutaroyl analogs of PAF, indicating a broader activity of PAF-AH in bile toward byproducts of glycerophospholipid peroxidation. Plasma PAF-AH activity was not altered 5 hours after LPS injection compared with saline injection, but it was significantly elevated 18 hours after endotoxin exposure. The levels of LCAT in bile were low and declined to nearly undetectable values by 5 hours after cannulation in both control and LPS-exposed rats. Plasma LCAT activity was significantly increased after 5 hours and decreased 18 hours after LPS injection. In summary, hepatic exposure to endotoxin results in a rapid increase in biliary secretion of PAF-AH followed by elevation of LCAT and PAF-AH levels in plasma. We propose that biliary secretion of PAF-AH may be involved in the hepatic response to endotoxic insult by counteracting potential inflammatory damage in the biliary tree and gastrointestinal tract, whereas plasma increases in LCAT and PAF-AH may promote elimination of excess PAF and oxidized phospholipids in the circulation.

Lack of viral escape and defective in vivo activation of human immunodeficiency virus type 1-specific cytotoxic T lymphocytes in rapidly progressive infection

Human immunodeficiency virus type 1 (HIV-1)-specific immune responses over the course of rapidly progressive infection are not well defined. Detailed longitudinal analyses of neutralizing antibodies, lymphocyte proliferation, in vivo-activated and memory cytotoxic T-lymphocyte (CTL) responses, and viral sequence variation were performed on a patient who presented with acute HIV-1 infection, developed an AIDS-defining illness 13 months later, and died 45 months after presentation. Neutralizing-antibody responses remained weak throughout, and no HIV-1-specific lymphocyte proliferative responses were seen even early in the disease course. Strong in vivo-activated CTL directed against Env and Pol epitopes were present at the time of the initial drop in viremia but were quickly lost. Memory CTL against Env and Pol epitopes were detected throughout the course of infection; however, these CTL were not activated in vivo. Despite an initially narrow CTL response, new epitopes were not targeted as the disease progressed. Viral sequencing showed the emergence of variants within the two targeted CTL epitopes; however, viral variants within the immunodominant Env epitope were well recognized by CTL, and there was no evidence of viral escape from immune system detection within this epitope. These data demonstrate a narrowly directed, static CTL response in a patient with rapidly progressive disease. We also show that disease progression can occur in the presence of persistent memory CTL recognition of autologous epitopes and in the absence of detectable escape from CTL responses, consistent with an in vivo defect in activation of CTL.

Cellular and molecular biology of the liver

This paper highlights several key issues, ideas, and findings that significantly contribute to our understanding of the organization, communication, and molecular machinery of the liver. The functional anatomy of the liver has been studied in several ways that have revealed the extent of the biliary tree within the hepatic parenchyma, including identification of the canals of Hering as their most distal ramification. The canals of Hering are also considered as the potential residence of hepatic progenitor cells. Hepatocytes can "communicate" with each other via gap junctions, but might also deliver hormones and nucleotides downstream to cholangiocytes. The interaction of inflammatory cells and inflammatory mediators with hepatocytes is of particular importance in transplant immunology, infection, inflammation, viral hepatitis, and fibrogenesis. The role of these mediators as well as certain "toxic" bile acids in apoptosis has become clearer with the discovery of the mitochondrial permeability transition. Moreover, ursodeoxycholic acid can reduce apoptosis by minimizing the mitochondrial permeability transition. Two new nuclear hormone receptors, PXR and SXR, have been identified. These are both activated by a variety of chemically distinct ligands, whose final common goal is the activation of cytochrome P450-containing drug-metabolizing enzymes. Thus, these two receptors are critical to the body's ability to metabolize a variety of compounds properly. Additional insight into the role of cytokines and cytokine receptors in liver regeneration is presented. Finally, in vivo gene therapy of liver-expressed genes by chimeric oligonucleotides appears quite promising as a means of correcting single nucleotide gene defects.

Agricultural hazard data from a population-based survey of cash grain farms: Ohio observations

In response to congressional concerns, the National Institute for Occupational Safety and Health (NIOSH) initiated a multistate agricultural surveillance effort in 1990. The Farm Family Health and Hazard Surveillance (FFHHS) program involved separate population-based surveillance efforts by six state agencies or universities which gathered health and hazard data on farm operators and farm families. The results of the Ohio program are presented as an example of the data collection capabilities developed during the course of this project, which include the application of these data in documenting the prevalence of specific agricultural occupational hazards as well as the current attitudes of agricultural operators toward control and elimination of safety and health hazards. Specifically, three operationally defined areas of hazard audit (Structures, Landscape, and Mobile Equipment) are examined for the prevalence of such safety hazards as potential electrical shock, slippery or badly maintained walkways, inadequate chemical and fuel storage, and missing farm equipment moving-part guards. Questionnaire survey response examples are presented as an indication of farm operator attitudes toward safety and health training, on-site professional service access, and use of personal protective equipment. Current plans for data use and distribution, and the potential applications of the data as an occupational safety and health tool are also discussed.

Neutralization escape in human immunodeficiency virus type 1-infected long-term nonprogressors

Neutralization-escape variants of human immunodeficiency virus type 1 (HIV-1) were sought in persons who had persistent low virus loads and who remained asymptomatic for at least 12-16 years of infection without antiretroviral therapy. Viruses were isolated from 3 persons at two or three time points during the course of infection and were assessed for neutralization by sequential autologous serum samples. Virus neutralization was poor or undetectable with contemporaneous autologous serum but improved with later serum samples for each person. In particular, later isolates resisted neutralization by autologous serum samples that neutralized an earlier isolate. Strain-specific neutralizing antibodies remained detectable for up to 4.2 years without diminishing in titer. The results demonstrate that neutralization-escape variants arise periodically in HIV-1-infected long-term nonprogressors.

In vivo identification of colonic dysplasia using fluorescence endoscopic imaging

BACKGROUND

Previous in vitro studies showed that autofluorescence images of colonic mucosa collected endoscopically can be used to detect dysplasia with high sensitivity. This method is extended to the collection of fluorescence images of adenomatous polyps in vivo.

METHODS

Fluorescence images were collected during colonoscopy in 30 patients. A total of 12 adenomatous and 6 hyperplastic polyps were identified. A fiberoptic excitation probe, located in the instrument channel of the colonoscope, delivered 300 mW of near-ultraviolet light at lambdaex = 351 and 364 nm. Mucosal fluorescence in the spectral bandwidth between 400 and 700 nm was imaged, processed, and displayed with various likelihoods of associated dysplasia.

RESULTS

Adenomatous polyps exhibited decreased fluorescence intensity compared with adjacent mucosa with normal appearance. With the fluorescence threshold set to 80% of the average intensity of normal mucosa, a sensitivity of 83% for dysplasia identification was achieved. All hyperplastic polyps were correctly identified as being non-dysplastic. Optimal identification of dysplastic regions was obtained with the colonoscope oriented at a near-normal angle of incidence to the polyps. At higher angles of incidence, artifacts caused by illumination shadows were introduced.

CONCLUSIONS

The dysplasia associated with adenomatous polyps can be identified in vivo by fluorescence imaging with high sensitivity, thus demonstrating the potential to guide endoscopic procurement of biopsy specimens.

Prevalence of chronic respiratory symptoms among Ohio cash grain farmers

BACKGROUND

The prevalence of chronic cough, chronic phlegm, dyspnea, and non-cold wheeze was estimated from a mixed-mode survey of Ohio cash grain farmers in 1993.

METHODS

Personal characteristics of the principal operators (POs) such as age and cigarette smoking, in addition to selected farm characteristics and relevant medical and work history factors potentially associated with both exposure to respiratory irritants and subsequent respiratory symptoms were considered.

RESULTS

The overall design-adjusted prevalences (and the corresponding 95% confidence intervals (CIs) were: 9.4% (7.6-11.1%) for chronic cough, 10.8% (9.0-12.6%) for chronic phlegm, 16.2% (14.1-18.3%) for dyspnea, and 8.1% (6.4-9.8%) for non-cold wheeze. In univariate and multivariate analyses, smoking status was found, not surprisingly, to be the strongest predictor of increased symptom prevalence compared to all other factors. Other non-occupational factors found associated with increased symptom prevalence include age (cough, phlegm, dyspnea) and pet allergy (non-cold wheeze). Occupational factors found at least weakly associated with increased symptom prevalence include lifetime hours of cab tractor operation (cough); percent time spent farming (phlegm); having livestock other than cattle, cows, and calves (dyspnea); acres of corn for silage or green chop (cough); acres of alfalfa hay (non-cold wheeze); and personal involvement with pesticides (cough).

CONCLUSIONS

Symptom prevalences reported here are consistent with previous findings from studies of other groups of farmers. Results pertaining to factors found associated with symptom prevalences should be interpreted in light of several sources of potential bias.

Cellularization in Drosophila melanogaster is disrupted by the inhibition of rho activity and the activation of Cdc42 function

Regulation of cytoskeletal dynamics is essential for cell shape change and morphogenesis. Drosophila melanogaster embryos offer a well-defined system for observing alterations in the cytoskeleton during the process of cellularization, a specialized form of cytokinesis. During cellularization, the actomyosin cytoskeleton forms a hexagonal array and drives invagination of the plasma membrane between the nuclei located at the cortex of the syncytial blastoderm. Rho, Rac, and Cdc42 proteins are members of the Rho subfamily of Ras-related G proteins that are involved in the formation and maintenance of the actin cytoskeleton throughout phylogeny and in D. melanogaster. To investigate how Rho subfamily activity affects the cytoskeleton during cellularization stages, embryos were microinjected with C3 exoenzyme from Clostridium botulinum or with wild-type, constitutively active, or dominant negative versions of Rho, Rac, and Cdc42 proteins. C3 exoenzyme ADP-ribosylates and inactivates Rho with high specificity, whereas constitutively active dominant mutations remain in the activated GTP-bound state to activate downstream effectors. Dominant negative mutations likely inhibit endogenous small G protein activity by sequestering exchange factors. Of the 10 agents microinjected, C3 exoenzyme, constitutively active Cdc42, and dominant negative Rho have a specific and indistinguishable effect: the actomyosin cytoskeleton is disrupted, cellularization halts, and embryogenesis arrests. Time-lapse video records of DIC imaged embryos show that nuclei in injected regions move away from the cortex of the embryo, thereby phenocopying injections of cytochalasin or antimyosin. Rhodamine phalloidin staining reveals that the actin-based hexagonal array normally seen during cellularization is disrupted in a dose-dependent fashion. Additionally, DNA stain reveals that nuclei in the microinjected embryos aggregate in regions that correspond to actin disruption. These embryos halt in cellularization and do not proceed to gastrulation. We conclude that Rho activity and Cdc42 regulation are required for cytoskeletal function in actomyosin-driven furrow canal formation and nuclear positioning.

A cross-sectional case control study of work-related injuries among Ohio farmers

The agricultural industry has consistently been ranked among the most hazardous in the U.S. To date, few analytic studies of occupational injury among farm operators and workers have been conducted. A case control study was undertaken to investigate risk factors for agricultural work-related injury among Ohio farm operators. Cases were selected from among 1,793 respondents to a questionnaire administered during the first phase of the NIOSH-sponsored Ohio Farm Family Health and Hazard Study (OFFHHS). Analysis consisted of description of the injury experience of the sample as a whole, followed by logistic estimation of prevalence odds ratios (pORs) measuring the effect of potential risk factors on injury risk. The case series consisted of 90 white male principal operators (POs) injured doing farm work in the 12 months prior to questionnaire completion. Controls consisted of 1,475 white male POs who reported no injuries. The overall rate of injury was 5 per 100 person-years. The most notable result is the relationship between self-reported neurotoxic symptoms and injury, suggesting those with more reported symptoms were at greater risk of injury. The crude OR, when compared to the reference score of < or = 27, increased from 1.74 (95% CI = 0.60-5.09) in the 28-30 category, to 1.89 (95% CI = 0.71-5.03) in the 31-35 category, to 2.96 (95% CI = 1.10-7.96) in the highest category of test score. The P value for trend was 0.0218. These associations largely persisted after controlling for potential confounders with multiple logistic regression. Risk was inversely related to age. The results show marked increases in risk of injury associated with farmers younger than 30 and increased severity of self-reported neurological symptoms, controlling for potential confounding.

Tumor necrosis factor- alpha production to lipopolysaccharide stimulation by donor cells predicts the severity of experimental acute graft-versus-host disease

Donor T cell responses to host alloantigen are known predictors for graft-versus-host disease (GVHD); however, the effect of donor responsiveness to an inflammatory stimulus such as lipopolysaccharide (LPS) on GVHD severity has not been investigated. To examine this, we used mouse strains that differ in their sensitivity to LPS as donors in an experimental bone marrow transplant (BMT) system. Lethally irradiated (C3FeB6)F1 hosts received BMT from either LPS-sensitive (LPS-s) C3Heb/Fej, or LPS-resistant (LPS-r) C3H/ Hej donors. Mice receiving LPS-r BMT developed significantly less GVHD as measured by mortality and clinical score compared with recipients of LPS-s BMT, a finding that was associated with significant decreases in intestinal histopathology and serum LPS and TNF-alpha levels. When donor T cell responses to host antigens were measured, no differences in proliferation, serum IFN-gamma levels, splenic T cell expansion, or CTL activity were observed after LPS-r or LPS-s BMT. Systemic neutralization of TNF-alpha from day -2 to +6 resulted in decreased intestinal pathology, and serum LPS levels and increased survival after BMT compared with control mice receiving Ig. We conclude that donor resistance to endotoxin reduces the development of acute GVHD by attenuating early intestinal damage mediated by TNFalpha. These data suggest that the responsiveness of donor accessory cells to LPS may be an important risk factor for acute GVHD severity independent of T cell responses to host antigens.

Host reactive donor T cells are associated with lung injury after experimental allogeneic bone marrow transplantation

Noninfectious lung injury is common after allogeneic bone marrow transplantation (BMT), but its association with acute graft-versus-host disease (GVHD) is unclear. Using a murine BMT system where donor and host differ by multiple minor histocompatibility (H) antigens, we investigated the nature of lung injury and its relationship both to systemic GVHD and host-reactive donor T cells. Lethally irradiated CBA hosts received syngeneic BMT or allogeneic (B10.BR) T-cell-depleted (TCD) bone marrow (BM) with and without the addition of T cells. Six weeks after BMT, significant pulmonary histopathology was observed in animals receiving allogeneic BMT compared with syngeneic controls. Lung damage was greater in mice that received allogeneic T cells and developed GVHD, but it was also detectable after TCD BMT when signs of clinical and histologic acute GVHD were absent. In each setting, lung injury was associated with significant alterations in pulmonary function. Mature, donor (Vbeta6(+) and Vbeta3(+)) T cells were significantly increased in the broncho-alveolar lavage (BAL) fluid of all allogeneic BMT recipients compared with syngeneic controls, and these cells proliferated and produced interferon-gamma (IFN-gamma) to host antigens in vitro. These in vitro responses correlated with increased IFN-gamma and tumor necrosis factor-alpha (TNF-alpha) in the BAL fluid. We conclude that alloreactive donor lymphocytes are associated with lung injury in this allogeneic BMT model. The expansion of these cells in the BAL fluid and their ability to respond to host antigens even when systemic tolerance has been established (ie, the absence of clinical GVHD) suggest that the lung may serve as a sanctuary site for these host reactive donor T cells. These findings may have important implications with regard to the evaluation and treatment of pulmonary dysfunction after allogeneic BMT even when clinical GVHD is absent.

The normal adult human liver biopsy: a quantitative reference standard

In assessing adult human liver histology, questions remain concerning the normal number of portal tracts and bile ducts in a liver biopsy. We therefore reviewed liver biopsies obtained with use of a percutaneous Menghini cutting needle (14G, internal diameter 1.6 mm), from 16 patients undergoing liver biopsy for screening procedures (age 49 +/- 14 years, +/-SD) and found to be normal by histological examination. The average aggregate length of the liver tissue was 1.8 +/- 0.8 cm (area of 16.4 +/- 10.7 mm2), representing 7 +/- 3 tissue fragments. Portal triads containing at least one profile each of a portal vein, hepatic artery, and interlobular bile duct numbered 11 +/- 6 per biopsy (range 3-23). Portal dyads, which did not contain one of these profiles, usually the portal vein, numbered 8 +/- 5 (range 1-18). On a per-specimen basis, 38% of portal tracts did not contain a portal vein, 7% did not contain a bile duct, and 9% did not contain a hepatic artery. Because of multiplicity of profiles within portal tracts, however, the average number of profiles per portal tract was 6 +/- 5 (range 2-35). Notably, on average there were 2.3 +/- 2.2 interlobular bile ducts per portal tract, compared to 2.6 +/- 2.3 hepatic arteries and 0.7 +/- 0.7 portal veins. The average minimum external diameter of interlobular bile ducts was 13 +/- 4 microm, of hepatic arteries 12 +/- 5 microm, and of portal veins 35 +/- 25 microm. Bile ducts greater than 30 microm in diameter were rare, only one each in two biopsies were observed. In contrast, probable canals of Hering were occasionally evident at the periphery of portal tracts (6 +/- 6 per biopsy) and within the lobular parenchyma as strings of cuboidal cells (5 +/- 5 per biopsy). We conclude that, although multiplicity of profiles is normal, portal dyads are almost as common as portal triads in normal peripheral liver tissue. On average, there are two interlobular bile ducts, two hepatic arteries, and one portal vein per portal tract, with 6 full portal triads per linear cm of tissue obtained by external Menghini biopsy technique with use of a 14G needle, equivalent to 0.8 +/- 0.5 portal triads per mm2. By serving as a reference standard for adult human liver histology, these findings may assist in the histopathological assessment of liver biopsies, particularly those performed for disease conditions featuring loss of intrahepatic bile ducts.

Molecular characterization of the hemagglutinin gene and oral immunization with a waterfowl-origin avian influenza virus

Vaccination against highly pathogenic (HP) subtypes of avian influenza (AI) virus in poultry has been prohibited in the United States. Recently, policy has been changed to potentially allow use of inactivated vaccines in emergency programs to control HP H5 and H7 AI. Vaccination with inactivated virus against non-highly pathogenic AI viruses has been allowed in the U.S. turkey industry since 1979 (1) but requires expensive handling of individual birds for parenteral inoculation. Oral immunization would provide a less expensive method to protect commercial poultry from AI. Prime candidates for oral vaccines are waterfowl-origin (WFO) isolates, which have a tropism for the alimentary tract. One WFO isolate, A/mallard/Ohio/556/1987 (H5N9) (MOh87), was characterized by determining the complete nucleotide sequence of its hemagglutinin (HA) gene. The HA protein of this isolate possessed a deduced amino acid sequence nearly identical to the consensus amino acid sequence for all published H5 genes, indicating that it has potential as a broadly effective vaccine. Experimental results demonstrated measurable serum antibody responses to orally delivered live and inactivated preparations of MOh87. Oral vaccination also protected chickens from diverse, lethal H5 AI virus challenge strains and blocked cloacal shedding of challenge virus.

Interleukin-11 promotes T cell polarization and prevents acute graft-versus-host disease after allogeneic bone marrow transplantation

Administration of IL-11 prevented lethal graft-versus-host disease (GVHD) in a murine bone marrow transplant (BMT) model (B6 --> B6D2F1) across MHC and minor H antigen barriers (survival at day 50: 90 vs 20%, P < 0.001). Surpisingly, IL-11 administration polarized the donor T cell cytokine responses to host antigen after BMT with a 50% reduction in IFNgamma and IL-2 secretion and a 10-fold increase in IL-4. This polarization of T cell responses was associated with reduced IFNgamma serum levels and decreased IL-12 production in mixed lymphocyte cultures (MLC). In addition, IL-11 prevented small bowel damage and reduced serum endotoxin levels by 80%. Treatment with IL-11 also reduced TNFalpha serum levels and suppressed TNFalpha secretion by macrophages to LPS stimulation in vitro. IL-11 thus decreased GVHD morbidity and mortality by three mechanisms: (a) polarization of donor T cells; (b) protection of the small bowel; and (c) suppression of inflammatory cytokines such as TNFalpha. We conclude that brief treatment with IL-11 may represent a novel strategy to prevent T cell-mediated inflammatory processes such as GVHD.

Spectral pathology

We are investigating the use of optical spectroscopy (fluorescence, reflectance, Raman scattering) for detecting precancerous lesions in the mucosal linings of hollow organs. We present a morphological model for extracting quantitative pathological information from fluorescence spectra, using colonic dysplasia as an example. The potential of this technique in providing histological information in real time without the need for tissue removal is discussed.

Enhanced Na+-dependent bile salt uptake by WIF-B cells, a rat hepatoma hybrid cell line, following growth in the presence of a physiological bile salt

Although bile salts are toxic to the liver at high plasma concentrations, the effects of physiological concentrations of bile salts on normal hepatic function are poorly understood. We examined the effect of taurocholate (TC) on the basolateral uptake of [3H]TC in WIF-B cells, a hybrid cell line stably exhibiting in vitro the structural and functional polarity of hepatocytes. Cells were grown in the absence or presence of TC (50 micromol/L) over 12 days, and then incubated with [3H]TC concentrations ranging from 1 to 250 micromol/L. For both control and TC-grown cells, uptake of [3H]TC was linear over 2 minutes. In control cells, the Km for [3H]TC Na+-dependent uptake over 1 minute was 6 +/- 5 micromol/L, and the Vmax was 45 +/- 6 pmol TC/mg protein/min (+/- SEM). TC-grown cells exhibited no significant change in Km but showed a doubling of Vmax to 87 +/- 6 pmol TC/mg protein/min (P < .005). In both control and TC-grown cells, maximal uptake of [3H]TC occurred following 10 to 12 days in culture, with TC-grown cells consistently showing greater rates of [3H]TC uptake from 4 to 14 days in culture. Western blots immunostained for the basolateral Na+-dependent plasma membrane protein, ntcp, revealed the appropriate approximately 50-kd band in control and TC-grown cells, and confocal immunofluorescence microscopy demonstrated staining along the basolateral plasma membrane. Northern blots hybridized with a cDNA probe directed against ntcp indicated a modest TC-induced increase in mRNA levels. Reverse-transcriptase polymerase chain reaction (RT-PCR) using RNA isolated from WIF-B cells and oligonucleotide primers specific for rat ntcp or human NTCP transcripts revealed only the presence of the rat ntcp transcript. We conclude that bile salts, at concentrations normally found in mammalian portal blood, may be capable of promoting enhanced hepatocellular bile salt uptake via an increase in basolateral Na+-dependent plasma membrane transport capacity.

Hepatic secretion of phospholipid vesicles in the mouse critically depends on mdr2 or MDR3 P-glycoprotein expression. Visualization by electron microscopy

Hepatocellular secretion of bile salts into the biliary space induces phospholipid and cholesterol secretion, but the mechanism for integrated lipid secretion is poorly understood. Knockout mice unable to make the canalicular membrane mdr2 P-glycoprotein exhibit normal rates of bile salt secretion, yet are virtually incapable of secreting biliary phospholipid and cholesterol. As the mdr2 P-glycoprotein is thought to mediate transmembrane movement of phospholipid molecules, this mouse model was used to examine the mechanism for biliary phospholipid secretion. In wild-type mdr2 (+/+) mice, ultrarapid cryofixation of livers in situ revealed abundant unilamellar lipid vesicles within bile canalicular lumina. Although 74% of vesicles were adherent to the external aspect of the canalicular plasma membrane, bilayer exocytosis was not observed. Vesicle numbers in mdr2 (+/-) and (-/-) mice were 55 and 12% of wild-type levels, respectively. In a strain of mdr2 (-/-) mice which had been "rescued" by heterozygous genomic insertion of the MDR3 gene, the human homologue of the murine mdr2 gene, vesicle numbers returned to 95% of wild-type levels. Our findings indicate that biliary phospholipid is secreted as vesicles by a process largely dependent on the action of the murine mdr2 P-glycoprotein or human MDR3 P-glycoprotein. We conclude that mdr2-mediated phospholipid translocation from the internal to external hemileaflet of the canalicular membrane permits exovesiculation of the external hemileaflet, a vesiculation process promoted by the detergent environment of the bile canalicular lumen.

Mixed-mode survey of female veterinarians yields high response rate

In a recent study of female veterinarians, a subgroup of health professionals growing rapidly in number, the authors employed a mixed-mode survey design in targeting the cohort of women graduating from all US veterinary colleges during the 11-year period 1970-80 (n = 2,997). The questionnaire elicited information on a variety of health and occupational factors and required 35 minutes on average to complete. In the first stage, a modified version of Dillman's Total Design Method for mailed, self-administered questionnaires was employed, yielding a response rate of 82.9%. In the second stage, a telephone interview of all mail non-respondents was attempted, yielding a response rate here of only 30.1%, but increasing the overall response rate among those contacted to 90.2%. Non-respondents differed little from mail (early) or telephone (late) respondents with respect to year of graduation and geographic region of veterinary college attendance. Gentle probing of telephone non-respondents suggested the personal nature of some questions and the amount of time required to answer all questions were the main reasons they chose not to participate. It therefore appears that conventional survey techniques may be successfully employed in health studies of health professionals, particularly if issues of great concern to the target population are addressed.

Total body irradiation and acute graft-versus-host disease: the role of gastrointestinal damage and inflammatory cytokines

The influence of bone marrow transplantation (BMT) conditioning regimens on the incidence and severity of graft-versus-host disease (GVHD) has been suggested in clinical BMT. Using murine BMT models, we show here an increase in GVHD severity in several donor-recipient strain combinations after intensification of the conditioning regimen by increasing the total body irradiation (TBI) dose from 900 cGy to 1,300 cGy. Increased GVHD was mediated by systemic increases in tumor necrosis factor alpha (TNF alpha). Histologic analysis of gastrointestinal tracts showed synergistic damage by increased TBI and allogeneic donor cells that permitted increased translocation of lipopolysacharide (LPS) into the systemic circulation. In vitro, LPS triggered excess TNF alpha from macrophages primed by the GVH reaction. In addition, macrophages isolated within 4 hours of conditioning were primed in proportion to the TBI dose itself to secrete TNF alpha. Thus, the higher TBI dose increased macrophage priming and increased gut damage after allogeneic BMT, causing higher systemic levels of inflammatory cytokines and subsequent severe GVHD. These data highlight the importance of conditioning in GVHD pathophysiology and suggest that interventions to prevent LPS stimulation of primed macrophages may limit the severity of GVHD after intensive conditioning for allogeneic BMT.

Evolution of H5 subtype avian influenza A viruses in North America

The phylogenetic relationships of the hemagglutinin (HA) and non-structural (NS) genes from avian influenza (AI) H5 subtype viruses of North American origin are presented. Analysis of the HA genes of several previously uncharacterized isolates from waterfowl and turkeys provided clear evidence of significant sequence variation and existence of multiple virus clades or sub-lineages, maintained in migratory waterfowl. Phylogenetic analysis of NS gene sequences further demonstrated multiple sub-lineages and also demonstrated re-assortment of two NS alleles in wild duck populations. Based on currently available HA1 gene sequences, at least four clades exist with waterfowl isolates included in three of the four groups. The most genetically unstable of these sub-lineages is composed of recent poultry isolates from the outbreak of AI in Central Mexico. This group of viruses, which replicated unabated in chickens for at least 16 months, exhibited an increased rate of mutation in both the HA and NS gene. Comparison of the HA1 sequence data for all available North American H5 subtype viruses demonstrated minimal variation both in and around the amino acids predicted to be involved in the HA receptor binding site. The sequences also revealed that migratory waterfowl, live poultry market chicken, and turkey isolates uniformly lack a glycosylation site at amino acid 236 in the HA protein which is present in commercial chicken isolates.

A longitudinal study of unsaturated iron-binding capacity and lactoferrin in unstimulated parotid saliva

Availability of iron is one important nutritional parameter for microbial growth in saliva. This longitudinal study measured the diurnal and day-to-day variations in the total iron (TI), total iron-binding capacity (TIBC), unsaturated iron-binding capacity (UIBC), and lactoferrin (LF) in unstimulated human parotid saliva. Saliva was collected from 15 young male subjects in the morning and afternoon hours each day for five consecutive days. The TI and TIBC were determined by flameless atomic absorption spectroscopy, and UIBC was determined by subtraction of TI from TIBC. The LF was determined by "sandwich" enzyme-linked immunosorbent assay (ELISA). One peripheral blood sample of each subject was also analyzed for TI, TIBC, and ferritin. The results showed no significant diurnal or day-to-day variation of TI, TIBC, UIBC, or LF in saliva for most subjects. However, significant between-subject variations were observed for most parameters. Variations ranged from subjects with constantly positive UIBC values to subjects with constantly negative UIBC values. The relationship between the LF values and the TI and TIBC values suggests that other iron-binding protein(s) are present in saliva. Also, saliva had significantly lower TIBC values than serum. This finding indicated that iron may be easily available in saliva. However, further studies are required to determine the relationship between UIBC value of saliva and oral and dental diseases, and also to detect the presence of other iron-binding proteins in saliva.

Lack of evidence for vesicle trafficking of fluorescent bile salts in rat hepatocyte couplets

The role of intracellular vesicles in the movement of bile salts through hepatocytes from blood to bile has not been resolved. To determine whether bile salts are sequestered during transit, rat hepatocyte couplets were incubated with the fluorescent bile salts cholyl-lysyl-fluorescein (CLF) and chenodeoxycholyl-lysyl-fluorescein (CDCLF). Cellular and canalicular fluorescence were measured by confocal scanning fluorescence microscopy; inhomogeneity in intracellular fluorescence was used to evaluate potential sequestering of bile salts. Mean cellular and canalicular fluorescence increased in parallel over 10 min, slightly exceeding (P < 0.05) the degree of increase in intracellular inhomogeneity. The microtubule inhibitor colchicine had no effect on cellular or canalicular fluorescence patterns. In contrast, the nonfluorescent bile salt taurocholate enhanced the recovery of microtubules from cold-induced depolymerization, measured by confocal immunofluorescence of beta-tubulin. Thus no evidence was obtained for intracellular sequestering of bile salts or microtubule-dependent trafficking before canalicular secretion; cellular uptake and distribution occurred in parallel with canalicular secretion. The previously documented dependence of bile salt secretion on intact microtubule function therefore appears to be an indirect rather than a direct consequence of microtubule-dependent events. In particular, enhanced microtubule assembly may play a role in bile salt-induced delivery of bile salt transporters to the canalicular membrane.

Sexual negotiation in the AIDS era: negotiated safety revisited

OBJECTIVE

To test the safety of the 'negotiated safety' strategy-the strategy of dispensing with condoms within HIV-seronegative concordant regular sexual relationships under certain conditions.

METHOD

Data from recently recruited cohort of homosexually active men (Sydney Men and Sexual Health cohort, n = 1037) are used to revisit negotiated safety. The men were surveyed using a structured questionnaire and questions addressing their sexual relationships and practice their own and their regular partner's serostatus, agreements entered into by the men concerning sexual practice within and outside their regular relationship, and contextual and demographic variables.

RESULTS

The findings indicate that a significant number of men used negotiated safety as an HIV prevention strategy. In the 6 months prior to interview, of the 181 men in seroconcordant HIV-negative regular relationships, 62% had engaged in unprotected anal intercourse within their relationship, and 91% (165 men) had not engaged in unprotected anal intercourse outside their relationship. Of these 165 men, 82% had negotiated agreements about sex outside their relationship. The safety of negotiation was dependent not only on seroconcordance but also on the presence of an agreement; 82% of the men who had not engaged in unprotected anal intercourse outside their regular relationship had entered into an agreement with their partner, whereas only 56% of those who had engaged in unprotected anal intercourse had an agreement. The safety of negotiation was also related to the nature of the safety agreement reached between the men and on the acceptability of condoms. Agreements between HIV-negative seroconcordant regular partners prohibiting anal intercourse with casual partners or any form of sex with a casual partner were typically complied with, and men who had such negotiated agreements were at low risk of HIV infection.

CONCLUSIONS

The adoption of the strategy of negotiated safety among men in HIV-seronegative regular relationships may help such men sustain the safety of their sexual practice.

Histologic liver abnormalities in an autopsy series of patients with rheumatoid arthritis

A retrospective review was performed on 188 autopsied cases of rheumatoid arthritis at our institutions during 1958-1985, prior to the widespread use of methotrexate. Hepatic histology was reported in 182 cases. All available microscopic liver slides from cases in which the autopsy report described portal tract inflammation, fibrosis, cirrhosis, tumour, amyloid, vasculitis, or infections involving the liver were examined and graded by a hepatic pathologist blinded to the original diagnosis, along with a representative sample of cases with reports describing fatty change or no hepatic pathologic abnormalities. Ninety normal and abnormal cases were reviewed from the 182 for which hepatic histology was available. Fifteen cases of diffuse fibrosis were identified upon blinded review. Two cases were graded as severe fibrosis (grades 3 or 4 on a scale of 0-4) without an identifiable pathologic cause, in both of which the liver disease was suspected premortem (alcohol abuse and viral hepatitis). Although the incidence of fibrosis in this series is slightly higher than that previously described, serious fibrotic liver disease was rare. These results support the current practice of limiting pre-treatment liver biopsies prior to methotrexate therapy to patients with suspected liver disease.

Transplantation of polarized type 2 donor T cells reduces mortality caused by experimental graft-versus-host disease

Acute graft-versus-host disease (GVHD) is thought to be initiated by alloreactive type 1 T cells that secrete gamma-interferon (IFN-gamma). IFN-gamma induces the production of inflammatory cytokines, e.g., tumor necrosis factor-alpha and interleukin (IL)-1, which are the distal mediators of GVHD. We demonstrate that the transplantation of polarized type 2 murine T cells (i.e., cells secreting IL-4 but not IFN-gamma) together with T-cell-depleted bone marrow results in a significant increase in survival (P<0.001) after bone marrow transplantation across minor histocompatibility barriers (B10.BR-->CBA/J). Further analysis demonstrated that increased survival in recipients of polarized type 2 T cells correlated with diminished production of both IFN-gamma and tumor necrosis factor-alpha but with increases in IL-4 2 weeks after transplantation. Despite improved survival, histologic changes of GVHD were evident in oral mucosal and hepatic tissues at 7 weeks after bone marrow transplantation. These data provide further evidence that inflammatory cytokines in the immediate posttransplant period are pivotal to the development of mortality but that they do not correlate with individual target organ damage.

Fluorescence endoscopic imaging of human colonic adenomas

BACKGROUND & AIMS

Endoscopic screening for sporadic colorectal cancer relies in part on the detection of adenomatous polyps. Nonpolypoid adenomas or flat dysplasia may go unrecognized by conventional endoscopy. This study attempted to develop and test a novel endoscopic method for detecting polypoid and nonpolypoid colonic adenomas.

METHODS

Colectomy specimens from 3 patients with familial adenomatous polyposis containing polypoid and nonpolypoid adenomas were illuminated with excitation light at 351 and 364 nm. Endoscopic images of the net tissue fluorescence emitted were collected over the spectral bandwidth from 400 to 700 nm. Each raw image was corrected for differences in distance and instrument light collection efficiency by normalizing to a spatially averaged image. Intensity thresholding was then used to identity regions of diseased mucosa.

RESULTS

The average fluorescence intensity from normal mucosa was found to be greater than that from adenomas by a factor of 2.2 +/- 0.6. The sensitivity and specificity for detecting a region of dysplasia varied with the threshold value selected. At a threshold of 75% of the average normal intensity, a sensitivity of 90% and a specificity of 92% were achieved.

CONCLUSIONS

Fluorescence images of colonic mucosa can be collected endoscopically, and dysplasia can be detected and localized with high sensitivity and specificity. These results show the potential of this technique to direct endoscopic biopsy.

An experimental model of idiopathic pneumonia syndrome after bone marrow transplantation: I. The roles of minor H antigens and endotoxin

Idiopathic pneumonia syndrome (IPS) refers to diffuse, non-infectious pneumonia that occurs after allogeneic bone marrow transplantation (BMT). We have developed a model of IPS using a well-characterized murine BMT system (B10.BR-->CBA) in which lung injury after BMT can be induced by minor histocompatibility (H) antigenic differences between donor and host. Lung pathology and broncho-alveolar lavage (BAL) fluid were analyzed in transplant recipients before and after both syngeneic and allogeneic BMT. At 2 weeks after BMT, no specific pathologic abnormalities were noted; at 6 weeks, both pneumonitis and mononuclear cell infiltration around vessels and bronchioles were observed only in mice receiving allogeneic BMT. This injury was associated with elevated BAL fluid levels of endotoxin (lipopolysaccharide [LPS]), neutrophils, and tumor necrosis factor alpha. No pathologic organisms were isolated from the respiratory tract of any animal. We also tested the role of endotoxin in the development of this injury. Injection of LPS 6 weeks after transplantation caused profound lung injury only in mice with moderate graft-versus-host disease; dramatic increases in BAL neutrophils and tumor necrosis factor alpha were observed, with alveolar hemorrhage occurring in 4 of 12 of these mice but in no other group. We conclude that (1) this murine BMT system is a potentially useful model of clinical IPS; (2) minor H differences between donor and recipient can be important stimuli in the pathogenesis of IPS; and (3) endotoxin in BAL fluid is associated with lung injury, and excess endotoxin can cause the development of alveolar hemorrhage in this model.

Detection of dysplasia at colonoscopy using laser-induced fluorescence: a blinded study

BACKGROUND

Laser-induced fluorescence spectroscopy has the potential to detect colonic dysplasia in vivo. However, previous studies have limited their analyses to multivariate regression techniques and unblinded retrospective evaluation. The purpose of this study was to develop a probability-based algorithm to detect colonic dysplasia using laser-induced fluorescence spectroscopy and to evaluate it in a blinded manner.

METHODS

Fluorescence spectra were collected from normal mucosa and colonic polyps during colonoscopy using 370 nm excitation. Tissue was classified as normal, hyperplastic, or adenomatous by histologic examination. Preliminary data was used to devise an algorithm to differentiate tissue type based on probability distributions of the fluorescence intensity at 460 nm and the ratio of the intensity at 680 nm to that at 600 nm. The algorithm was then tested in a blinded fashion.

RESULTS

The algorithm correctly determined the tissue type in 88% of cases, equal to the agreement of independent pathologists. Sensitivity, specificity, and positive predictive value for the detection of dysplasia was 90%, 95%, and 90%, respectively.

CONCLUSIONS

Dysplasia was detected in vivo using fluorescence spectroscopy and a probability-based algorithm. This method may form the basis for a new surveillance technique for patients with increased risk for dysplastic transformation.

Heterogeneity in the haemagglutinin gene and emergence of the highly pathogenic phenotype among recent H5N2 avian influenza viruses from Mexico

Molecular changes in the haemagglutinin (HA)-coding regions and proteolytic cleavage sites from multiple H5N2 subtype viruses isolated during a recent outbreak of avian influenza (AI) in central Mexico have been characterized. Eighteen isolates, collected during a 15 month period (October 1993 to January 1995) from six central states, were sequenced. None of the 18 predicted HA1 amino acid sequences were identical and changes were not restricted to a specific region of the sequence. Phylogenetic analyses of the HA1 sequences demonstrated two virus lineages, designated Puebla and Jalisco, with sequence variation as high as 10.5 percent for amino acid and 6.2 percent for nucleotide sequences. During the latter months of the surveillance period, highly pathogenic (HP) strains of AI emerged causing lethal disease in commercial poultry flocks. In each of the HP strains isolated, the HA protein was cleaved in chicken embryo fibroblast cells in the absence of trypsin, and two alterations not found in earlier non-HP isolates were detected. In the HA protein, HP strains all had a glutamic acid --> lysine substitution at amino acid position 324 and an insertion of arginine and lysine as new residues 325 and 326. The insertion appears to be due to a duplication of the nucleotide sequence AAAGAA at nucleotide positions 965-970 of the HA1-coding region. Computer-assisted secondary structure analyses place the target for the insertion in a predicted RNA stem-loop structure. A mechanism is suggested by which the polymerase duplicates the sequence.

A multi-center clinical trial of a new chairside test in distinguishing between diseased and healthy periodontal sites. II. Association between site type and test outcome before and after therapy

The aim of the present study was to evaluate the association between the outcome of a chairside test measuring gingival crevicular fluid (GCF) levels of the enzyme aspartate aminotransferase (AST) and other clinical measures of disease including probing depth, severity of inflammation, and GCF flow before and after therapy. We studied 91 patients with moderate to severe periodontitis. Eight sites with probing depths between 5 mm and 8 mm and obvious signs of inflammation were selected and designated diseased sites. Four sites with probing depth < or = 3 mm with no or minimal signs of inflammation were selected and designated non-diseased sites in patients. Thirty healthy individuals were enrolled and four sites in each were selected and designated healthy controls. Patients were treated with scaling and root planing and control subjects with supragingival prophylaxis. Measurements including GCF volume, gingival inflammation, and probing depth were performed at screening baseline, 1 week later at pretreatment baseline, and at weeks 2 and 4 after treatment. AST content of GCF was measured using a chairside colorometric test. It was concluded that the outcome of the test is an effective objective measure distinguishing between diseased sites and non-diseased sites in patients and control subjects when evaluated both prior to and following application of therapy. Use of this simple chairside test, when combined with other standard diagnostic procedures, provides an objective measurement permitting improved capacity to distinguish between diseased and non-diseased periodontal sites, and to better assess and monitor the outcome of therapy.

Role of vesicle-mediated transport pathways in hepatocellular bile secretion

Bile formation by hepatocytes involves the secretion of organic and inorganic solutes derived from a number of intracellular sources. Plasma-to-bile trafficking of bile salts and proteins, in particular, is a major route for solute movement through the hepatocyte. Intracellular vesicle trafficking is the primary pathway for delivery of plasma proteins to bile, via either fluid-phase or receptor-mediated endocytosis. In contrast, bile salts do not appear to traffic via vesicles. Rather, bile salts appear to promote the insertion of vesicles containing the apical transport proteins into the hepatocyte canalicular membrane. Lysosomal protein also is released into bile by fusion of vesicles or possibly of tubular lysosomes with the canalicular membrane. Structural phospholipid is presumably delivered to the canalicular membrane as part of vesicular traffic, but biliary phosphatidylcholine molecules are more likely delivered via binding to cytosolic transfer proteins. Cholesterol may be delivered either via cystolic proteins or via vesicular trafficking, the latter in conjunction with sphingomyelin recycling to and from the canalicular membrane. Lastly, the primary mechanism for phospholipid secretion into bile appears to be the budding of phospholipid vesicles from the exoplasmic hemileaflet of the hepatocyte canalicular membrane. Thus, vesicle-mediated pathways play a major role in a number of bile secretory mechanisms.

Morphological model of human colon tissue fluorescence

Fluorescence spectroscopy of tissue is a promising technique for early detection of precancerous changes in the human body. Investigation of the microscopic origin of the clinically observed tissue fluorescence can provide valuable information about the tissue's histology. The objective of this study was the development of a morphological model of colon tissue fluorescence which connects the clinically observed spectra with their underlying microscopic origins. Clinical colon tissue fluorescence which connects the clinically observed spectra with their underlying microscopic origins. Clinical colon tissue fluorescence spectra were modeled by measuring the intrinsic fluorescence properties of colon tissue on a microscopic level and by simulating light propagation in tissue using the Monte-Carlo method. The computed spectra were in good agreement with the clinical spectra acquired during colonoscopy, and exhibited the characteristic spectral features of the in vivo collected spectra. Our analysis quantitated these spectral features in terms of the intrinsic fluorescence properties of tissue and its general histological characteristics. The fluorescence intensity difference between normal and adenoma observed in vivo was found to be due to the increased hemoglobin absorption, the reduced mucosal fluorescence intensity, and the absence of submucosal fluorescence in adenomatous polyps. The increased red fluorescence in adenoma was found to be associated with the dysplastic crypt cell fluorescence.

A novel carbohydrate addition site on the hemagglutinin protein of a highly pathogenic H7 subtype avian influenza virus

The highly pathogenic (HP) avian influenza isolate, A/Fowl/Victoria/76 (H7N7), contains two naturally occurring hemagglutinin (HA) variants. The two hemagglutinin proteins differ only in the possession of a potential asparagine-linked glycosylation site at amino acid position 188-190, which is near the proposed receptor binding region of the HA. Expanded virus plaques which possess the addition site exhibit more slowly migrating HA1 subunits and are significantly more lethal in chickens than those which lack the site. When artificial mixtures of the two variants were inoculated in birds, as few as 1 in 1000 particles containing the glycosylation site was sufficient to exhibit 100% lethality in birds. The data raise the possibility that presence of carbohydrate near the receptor site on the H7 avian influenza virus hemagglutinin may influence virulence.

Imaging biliary lipid secretion in the rat: ultrastructural evidence for vesiculation of the hepatocyte canalicular membrane

Physical-chemical and biological studies of hepatic bile suggest that biliary phospholipid molecules are secreted as unilamellar vesicles. Systematic ultrastructural studies of bile canaliculi were undertaken to visualize this event. Liver tissue was obtained from normal adult male rats (control), from bile salt-depleted rats (by overnight biliary diversion), and from depleted rats infused intravenously with a hydrophilic-hydrophobic congener series of common taurine-conjugated bile salts. Livers were fixed in situ either by modified chemical methods or by ultrarapid cryofixation. In control rats, chemical fixation revealed unilamellar vesicles 63 +/- 17 (+/- SD) nm in diameter, mostly free within canalicular lumena. Vesicles were infrequent in canaliculi of bile salt-depleted rats, but were present in canaliculi of rats infused with taurocholate. In cryofixed liver tissue, vesicles 67 +/- 13 nm in diameter were observed in canaliculi of control rats and bile-salt depleted rats infused with common bile salts. The majority of these vesicles were affixed to the luminal side of the canalicular membrane. The average number of vesicles per bile canaliculus was in agreement with that estimated on the basis of biliary phospholipid secretion rates, mean vesicle size, and area of close-packed phosphatidylcholine molecules. By immunoelectron microscopy, canalicular vesicles were free of actin and of a 100 kDa canalicular membrane protein. We conclude that biliary phospholipid molecules are secreted from hepatocytes into bile canalicular lumena as unilamellar vesicles approximately 63-67 nm in average diameter. We postulate that this secretion mechanism involves lumenal bile salt-induced vesiculation of lipid microdomains in the exoplasmic hemileaflet of the canalicular membrane.

A multicenter clinical trial of PerioGard in distinguishing between diseased and healthy periodontal sites. (I). Study design, methodology and therapeutic outcome

We designed and performed a multicenter clinical trial to determine the relationship between measurements of the level of the enzyme aspartate aminotransferase (AST) in gingival crevicular fluid (GCF) to other measures used to detect periodontal disease and monitor outcome of treatment, including pocket depth and gingival inflammation. 32 periodontitis patients were enrolled at the University of Washington, Seattle, 30 at the University of Florida, Gainesville, and 34 at the University of Illinois, Chicago. 10 periodontally normal control subjects were enrolled at each location. 8 diseased and 4 healthy sites were designated for study in each patient and 8 healthy sites designated in each control subject. Measures of disease included pocket depth, severity of gingival inflammation, and GCF volume. AST levels were measured using the PerioGard test kit. Clinical measurements were made and GCF samples harvested and tested 2x before and 2x after therapy consisting of scaling and root planing under local anesthetic. Specific design and other issues are discussed, including selection of patients and control subjects, sample size, selection of experimental test sites, methods for assessment of diseased and therapeutic improvement, harvesting of GCF and selection of appropriate biostatistical methods for data analysis. Demographics of the patient populations at the 3 locations are reported. As expected, therapy induced only negligible changes in the measures of disease at healthy sites in control subjects, and relatively minor improvement in healthy sites in patients. In contrast, statistically significant improvement relative to pretreatment baseline status in all 3 measures of disease was observed for diseased sites at all 3 study locations with all p-values less than 0.0002. The magnitude of improvement was comparable to that reported previously by others. The % of PerioGard-positive sites decreased significantly between the screening baseline and both post-treatment visits for patients at all 3 locations, with p values of 0.0001 to <0.0008.

Role of bile salt hydrophobicity in hepatic microtubule-dependent bile salt secretion

Under basal conditions, bile salt secretion by the liver is not affected by microtubule disruption. However, when a bile salt load is imposed on the liver, a microtubule-dependent secretion mechanism is recruited (J. Lipid Res. 1988. 29: 144-156). We tested the hypothesis that recruitment of this microtubule-dependent mechanism is influenced by the relative hydrophobicity of the bile salts being secreted. Intact male rats were depleted of bile salts by overnight biliary diversion, pretreated with colchicine (a microtubule inhibitor) or its inactive isomer, lumicolchicine (control), and reinfused intravenously with bile salts of increasing hydrophobicity (taurodehydrocholate < tauroursodeoxycholate < taurocholate) at 200 nmol/min.100 g. After 45 min, when steady-state bile salt secretion was achieved, tracer [3H]taurocholate was administered intravenously. The colchicine-insensitive component of bulk bile salt secretion was constant at approximately 130 nmol/min.100 g, and the colchicine-sensitive component increased from approximately 0 to 35 and 60 nmol/min.100 g, respectively, with reinfusion of the more hydrophobic bile salts. Retained bile salts accumulated in the liver and serum and were detectable in urine. Peak biliary secretion of [3H]taurocholate in control animals increased linearly from 15.3 to 18.0% administered dose/min with increasing hydrophobicity of the secreted bile salts (P < 0.002). In colchicine-pretreated animals, peak secretion rates decreased linearly from 13.8 to 9.2%/min (P < 0.001), with maximal inhibition in taurocholate-reinfused animals (P < 0.01). Utilization of a microtubule-dependent secretion mechanism increases with increasing bile salt hydrophobicity. This mechanism permits more efficient hepatic secretion of bile salts, but increases the susceptibility of bile salt secretion to microtubule disruption. We postulate that microtubule-dependent insertion of bile salt transporters into the canalicular membrane underlies the enhanced bile salt secretion observed when a bile salt load is imposed upon the liver.

Ultrastructural localization of a fluorinated bile salt in hepatocytes

BACKGROUND

Interactions of bile salts with hepatocellular organelles are critical for the formation of bile, yet these interactions remain poorly characterized. We present a novel approach for visualizing bile salts at the ultrastructural level within hepatocytes, using a unique fluorinated bile salt conjugate and electron energy loss spectroscopy.

EXPERIMENTAL DESIGN

Isolated rat hepatocytes were incubated for 5 and 20 minutes with the 2-fluoro-beta-alanine (FBAL) N-acyl amidate conjugate of cholic acid (C-FBAL, 50 microM). FBAL is a byproduct of hepatic 5-fluorouracil catabolism, and when conjugated to cholic acid is excreted into bile in a manner similar to the naturally occurring N-acyl amidates of bile salts. Cells were subjected to rapid cryofixation and automated freeze-drying followed by vapor-phase fixation using the LifeCell system, thus avoiding exposure to the leaching action of liquid fixatives. After resin infiltration, the cellular distribution of fluorine was determined in ultrathin sections with a Zeiss CEM902 electron microscope equipped for electron energy loss spectroscopy.

RESULTS

Fluorine was detected primarily in association with intracellular membranes, particularly membranes of the endoplasmic reticulum (p < 0.05 at 20 minutes by morphometric analysis). Fluorine also was detected in association with membranes of the Golgi apparatus. The fluorine signal was confirmed by serial spectra of cell regions containing these organelles (p < 0.01), but was not detectable in the free cytosol, mitochondria or extracellular medium, nor in hepatocytes not exposed to C-FBAL.

CONCLUSIONS

We conclude that cryofixation and freeze-dry processing followed by electron microscopy with electron energy loss spectroscopy is a valuable technique for examining intracellular processing of bile salts. Our results suggest that bile salts localize to the membranes, but not lumena, of organelles during hepatocyte exposure to bile salts, calling into question the proposed role for vesicular transport of bile salts within hepatocytes.

Cell adhesion molecules in inflammation and immunity: relevance to periodontal diseases

Inflammatory and immune responses involve close contact between different populations of cells. These adhesive interactions mediate migration of cells to sites of inflammation and the effector functions of cells within the lesions. Recently, there has been significant progress in understanding the molecular basis of these intercellular contacts. Blocking interactions between cell adhesion molecules and their ligands has successfully suppressed inflammatory reactions in a variety of animal models in vivo. The role of the host response in periodontal disease is receiving renewed attention, but little is known of the function of cell adhesion molecules in these diseases. In this review we summarize the structure, distribution, and function of cell adhesion molecules involved in inflammatory/immune responses. The current knowledge of the distribution of cell adhesion molecules is described and the potential for modulation of cell adhesion molecule function is discussed.