Constitutive Model for Time-Dependent Flows of Shear-Thickening Suspensions

We develop a tensorial constitutive model for dense, shear-thickening particle suspensions subjected to time-dependent flow. Our model combines a recently proposed evolution equation for the suspension microstructure in rate-independent materials with ideas developed previously to explain the steady flow of shear-thickening ones, whereby friction proliferates among compressive contacts at large particle stresses. We apply our model to shear reversal, and find good qualitative agreement with particle-level, discrete-element simulations whose results we also present.

Effects of tail docking and tail biting on performance and welfare of growing-finishing pigs in a confinement housing system

A study was conducted to evaluate the effect of tail docking on the welfare and performance of victimized pigs by tail biting and tail biters. Pigs ( = 240; 25.7 ± 2.9 kg average weight), including 120 pigs that were tail docked at birth and 120 pigs that remained with intact tails, were used. Pigs were housed in 8 pens of 30 pigs in a confinement barn for 16 wk, with 4 pens each housing pigs of both sexes with docked or intact tails. Tail biters and victimized pigs with damaged tails were identified during outbreaks of tail biting. Growth performance was monitored, and skin lesions on the tail, ears, and body were assessed. Blood samples were collected from focal tail biters, victimized pigs, and nonvictimized pigs for analysis of total serum protein, IgG, and substance P concentrations. When pigs were marketed, carcass weights and the number of pigs with carcass trim loss were recorded. During the growing-finishing period, 48% of pigs with docked tails and 89% of pigs with intact tails experienced lesions on their tails, including 5% of docked pigs and 30% of intact pigs identified as victimized pigs that experienced puncture wounds with signs of infection on their tails or loss of tails ( < 0.001). Victimized pigs tended to gain less weight ( = 0.07) between 17 and 21 wk of age than other pigs when tail biting prevailed in this study. Victimized pigs were more frequently ( = 0.04) sold for less than full value and had a lower dressing percentage ( < 0.001) compared with nonvictimized pigs. For victimized pigs, total serum protein and IgG concentrations were elevated 5 d after tails were injured, suggesting that tail damage can cause inflammation, which may lead to carcass abscesses and trim loss. Compared with victimized pigs and nonvictimized pigs, tail biters had lower total serum protein ( = 0.01) and IgG ( = 0.01) concentrations, indicating that tail biters may experience poor immune functions. Results of this study demonstrated that tail docking reduced tail damage in pigs kept in a confinement system. Tail damage can cause inflammation and reduce the value of market pigs. More research is needed to test whether compromised immune functions predispose pigs to tail biting.

An investigation of side-effects and efficacy of foam-based sclerotherapy with carbon dioxide or room air in the treatment of reticular leg veins: a pilot study

OBJECTIVES

In sclerotherapy, carbon dioxide (CO(2)) or room air can be employed by phlebologists for foam creation. We compared room air (RA) and carbon dioxide in treating reticular leg veins with foam sclerotherapy.

METHODS

Twenty patients were randomly treated with RA- or CO(2)-created sodium tetradecyl sulphate (STS) foam. Concentration and volume of STS, side-effects and efficacy were determined.

RESULTS

There was no difference in the efficacy, local side-effects or distant side-effects between RA and CO(2) foam in the treatment of reticular leg veins. The total volume of foam sclerosant required for treatment was greater with CO(2) compared with RA (P value = 0.01).

CONCLUSION

No differences were found in efficacy or side-effects between RA- and CO(2)-foam sclerotherapy for reticular leg veins. CO(2) foam's shorter half-life was hypothesized to be responsible for larger total volumes of CO(2) foam sclerosant.

An investigation on the influence of glycerin on sclerosant foam stability

BACKGROUND

Foam sclerotherapy is an increasingly popular modality in the treatment of varicose veins. Foam stability varies according to foam composition, volume and injection technique.

MATERIALS AND METHODS

A disposable plastic connector was used to create foam from 0.50% sodium tetradecyl sulphate (STS) mixed with varying volumes of glycerin. As a measure of foam stability, the half liquid time was defined as the time required for half of the original volume of sclerosing solution to settle. Three recordings were determined for each of the three mixtures of sclerosant foam.

RESULTS

The time for sclerosing solution to settle to half of its initial volume was found to be 89 seconds for 0.50% STS alone, 117.7 seconds with the addition of 0.1 mL of 72% glycerin, and 114.7 seconds with the addition of 0.2 mL of 72% glycerin.

CONCLUSION

The small volumes of glycerin added to STS prolonged the half liquid time of STS foam up to 35%. As glycerin alone is unable to be foamed with the double-syringe system technique there may be a point at which further addition of glycerin has a negative effect on the half-life of foam.

Autoimmunity to type VII collagen in SKH1 mice is independent of regulatory T cells

Epidermolysis bullosa acquisita is an autoimmune blistering disease characterized by circulating and skin basement membrane-bound IgG autoantibodies to type VII collagen, a major structural protein of the dermal-epidermal junction. Regulatory T cells (T(reg)) suppress self antigen-mediated autoimmune responses. To investigate the role of T(reg) in the the autoimmune response to type VII collagen in a mouse model, a monoclonal antibody against mouse CD25 was used to deplete T(reg). A recombinant mouse type VII collagen NC1 domain protein and mouse albumin were used as antigens. SKH1 mice were used as a testing host. Group 1 mice received NC1 immunization and were functionally depleted of T(reg); group 2 mice received NC1 immunization and rat isotype control; and group 3 mice received albumin immunization and were functionally depleted of T(reg). Results demonstrated that anti-NC1 IgG autoantibodies with high titres, as determined by enzyme-linked immunosorbent assay and Western blotting, developed in all mice immunized with NC1 (groups 1 and 2), but were undetected in group 3 mice. The predominant subclasses of anti-NC1 autoantibodies were IgG1, IgG2a and IgG2b; furthermore, these antibodies carried only the kappa light chain. IgG autoantibodies in the sera of NC1-immunized mice reacted with mouse skin basement membrane in vitro and deposited in skin basement membrane in vivo as detected by indirect and direct immunofluorescence microscopy, respectively. Our data suggest that the development of autoimmunity against type VII collagen in mice is independent of T(reg) function and the autoimmune response is mediated by both Th1 and Th2 cells. We speculate that the basement membrane deposition of IgG may eventually lead to blister development.

Complete genome sequence of a virulent isolate of Streptococcus pneumoniae

The 2,160,837-base pair genome sequence of an isolate of Streptococcus pneumoniae, a Gram-positive pathogen that causes pneumonia, bacteremia, meningitis, and otitis media, contains 2236 predicted coding regions; of these, 1440 (64%) were assigned a biological role. Approximately 5% of the genome is composed of insertion sequences that may contribute to genome rearrangements through uptake of foreign DNA. Extracellular enzyme systems for the metabolism of polysaccharides and hexosamines provide a substantial source of carbon and nitrogen for S. pneumoniae and also damage host tissues and facilitate colonization. A motif identified within the signal peptide of proteins is potentially involved in targeting these proteins to the cell surface of low-guanine/cytosine (GC) Gram-positive species. Several surface-exposed proteins that may serve as potential vaccine candidates were identified. Comparative genome hybridization with DNA arrays revealed strain differences in S. pneumoniae that could contribute to differences in virulence and antigenicity.

The Comprehensive Microbial Resource

One challenge presented by large-scale genome sequencing efforts is effective display of uniform information to the scientific community. The Comprehensive Microbial Resource (CMR) contains robust annotation of all complete microbial genomes and allows for a wide variety of data retrievals. The bacterial information has been placed on the Web at http://www.tigr.org/CMR for retrieval using standard web browsing technology. Retrievals can be based on protein properties such as molecular weight or hydrophobicity, GC-content, functional role assignments and taxonomy. The CMR also has special web-based tools to allow data mining using pre-run homology searches, whole genome dot-plots, batch downloading and traversal across genomes using a variety of datatypes.

Altered responsiveness of medial prefrontal cortex neurons to glutamate and dopamine after withdrawal from repeated amphetamine treatment

Using in vivo extracellular single-cell recording and microiontophoresis, we compared the responsiveness of medial prefrontal cortex (mPFC) neurons (layers V-VI) to dopamine and glutamate in rats that had received repeated amphetamine or saline injections. Neurons from amphetamine-pretreated rats showed increased responsiveness to glutamate and decreased responsiveness to dopamine after three days of withdrawal, suggesting that the mPFC is transiently hyperexcitable during amphetamine withdrawal. Published 2000 Wiley-Liss, Inc.

Complete genome sequence of Neisseria meningitidis serogroup B strain MC58

The 2,272,351-base pair genome of Neisseria meningitidis strain MC58 (serogroup B), a causative agent of meningitis and septicemia, contains 2158 predicted coding regions, 1158 (53.7%) of which were assigned a biological role. Three major islands of horizontal DNA transfer were identified; two of these contain genes encoding proteins involved in pathogenicity, and the third island contains coding sequences only for hypothetical proteins. Insights into the commensal and virulence behavior of N. meningitidis can be gleaned from the genome, in which sequences for structural proteins of the pilus are clustered and several coding regions unique to serogroup B capsular polysaccharide synthesis can be identified. Finally, N. meningitidis contains more genes that undergo phase variation than any pathogen studied to date, a mechanism that controls their expression and contributes to the evasion of the host immune system.

Evidence for lateral gene transfer between Archaea and bacteria from genome sequence of Thermotoga maritima

The 1,860,725-base-pair genome of Thermotoga maritima MSB8 contains 1,877 predicted coding regions, 1,014 (54%) of which have functional assignments and 863 (46%) of which are of unknown function. Genome analysis reveals numerous pathways involved in degradation of sugars and plant polysaccharides, and 108 genes that have orthologues only in the genomes of other thermophilic Eubacteria and Archaea. Of the Eubacteria sequenced to date, T. maritima has the highest percentage (24%) of genes that are most similar to archaeal genes. Eighty-one archaeal-like genes are clustered in 15 regions of the T. maritima genome that range in size from 4 to 20 kilobases. Conservation of gene order between T. maritima and Archaea in many of the clustered regions suggests that lateral gene transfer may have occurred between thermophilic Eubacteria and Archaea.

Analysis of leukocytes recruited to the pancreas by diabetogenic T cell clones

To investigate host leukocytes recruited to the pancreas by diabetogenic T cells, we administered islet-specific CD4(+) T cell clones to 2-week-old nonobese diabetic (NOD) mice and examined the resulting pancreatic infiltrate by flow cytometry. Two different Vbeta4(+)CD4(+) T cell clones, BDC 2.5 and BDC 6.9, were found to recruit a heterogeneous T cell population as determined by staining with a panel of anti-TCR Vbeta monoclonal antibodies. The majority of the diabetes-initiating, Vbeta4(+) T cell clones migrated to the spleen whereas only 5-8% of the T cell population infiltrating the pancreas was Vbeta4(+). Anti-IL-2 receptor staining indicated that fewer than 10% of the total population of infiltrating lymphocytes within the pancreas were in a highly activated state. We have further found that normal splenic T cells from the NOD mouse proliferate poorly to IL-2 in vitro, yet secrete IFN-gamma in response to IL-2 stimulation. These results suggest that the recruited host T cells in our disease transfer system are not directly pathogenic but, rather, are responding to the small numbers of inflammatory T cell clones by providing cytokines that facilitate the disease process.

Inhibition of angiogenesis by interleukin 4

Interleukin (IL)-4, a crucial modulator of the immune system and an active antitumor agent, is also a potent inhibitor of angiogenesis. When incorporated at concentrations of 10 ng/ml or more into pellets implanted into the rat cornea or when delivered systemically to the mouse by intraperitoneal injection, IL-4 blocked the induction of corneal neovascularization by basic fibroblast growth factor. IL-4 as well as IL-13 inhibited the migration of cultured bovine or human microvascular cells, showing unusual dose-response curves that were sharply stimulatory at a concentration of 0.01 ng/ml but inhibitory over a wide range of higher concentrations. Recombinant cytokine from mouse and from human worked equally well in vitro on bovine and human endothelial cells and in vivo in the rat, showing no species specificity. IL-4 was secreted at inhibitory levels by activated murine T helper (TH0) cells and by a line of carcinoma cells whose tumorigenicity is known to be inhibited by IL-4. Its ability to cause media conditioned by these cells to be antiangiogenic suggested that the antiangiogenic activity of IL-4 may play a role in normal physiology and contribute significantly to its demonstrated antitumor activity.

Alcohol consumption alters antigen-specific Th1 responses: mechanisms of deficit and repair

Among the physiological effects associated with excessive alcohol consumption are alterations in immune function. Alcohol impairs T-helper 1 lymphocyte (Th1) regulated, cell-mediated immune responses. Antibody responses, regulated by T-helper 2 lymphocyte (Th2), are either unimpaired or enhanced. Antigen presenting cells are central to the development of both Th1 and Th2 regulated immune responses. We used both T-cell receptor transgenic and conventionally immunized mice to demonstrate that ethanol consumption directly affects antigen presenting cells that, in turn, determines whether Th1 or Th2 response patterns predominate. Ethanol consumption inhibits Th1-associated interleukin-12 and interferon-gamma cytokine production and delayed-type hypersensitivity. Administration of exogenous recombinant interleukin-12 both restores interferon-gamma levels and delayed-type hypersensitivity responses in ethanol-consuming mice.

Glutathione levels in antigen-presenting cells modulate Th1 versus Th2 response patterns

Current thinking attributes the balance between T helper 1 (Th1) and Th2 cytokine response patterns in immune responses to the nature of the antigen, the genetic composition of the host, and the cytokines involved in the early interaction between T cells and antigen-presenting cells. Here we introduce glutathione, a tripeptide that regulates intracellular redox and other aspects of cell physiology, as a key regulatory element in this process. By using three different methods to deplete glutathione from T cell receptor transgenic and conventional mice and studying in vivo and/or in vitro responses to three distinct antigens, we show that glutathione levels in antigen-presenting cells determine whether Th1 or Th2 response patterns predominate. These findings present new insights into immune response alterations in HIV and other diseases. Further, they potentially offer an explanation for the well known differences in immune responses in "Th1" and "Th2" mouse strains.

Interleukin-12 therapy restores cell-mediated immunity in ethanol-consuming mice

Previous studies from our laboratory show that ethanol consumption impairs antigen-specific, cell-mediated, but not, humoral immune responses of C57BL/6, BALB/c, and DO11.10 T-cell receptor transgenic mice. This ethanol-associated deficit is associated with decreased interleukin (IL)-12 and interferon-gamma (IFN-gamma) production, but not IL-2 or antigen-specific T-cell proliferation by explanted leukocytes from ethanol-consuming mice. IL-12 expression by macrophage/monocytes is viewed as a requirement for the production of IFN-gamma by Th1 lymphocytes that mediate cellular immunity. In this study, we restored antigen-specific, cell-mediated immunity, delayed hypersensitivity, to ethanol-consuming C57BL/6 or BALB/c mice with a single 100 ng of intravenous injection of recombinant IL-12 at the time of immunization. The addition of exogenous recombinant IL-12 to co-cultures of antigen-presenting cells derived from ethanol-consuming mice and purified T cells derived from ethanol-nonconsuming DO11.10 repairs the ability of Th1 cells to make IFN-gamma in response to antigen. Administration of recombinant IL-12 opens a potential for restoring cell-mediated immune function to ethanol-consuming individuals.

Human antibody responses to Trypanosoma cruzi 70-kD heat-shock proteins

Heat-shock proteins of the 70-kD (hsp70) family are targets of humoral and cellular immune responses following bacterial or parasitic infections, including Chagas' disease. In the present study, we measured antibodies in human sera reactive with hsp70s from the cytoplasm (cy-hsp70), mitochondrion (mt-hsp70), and endoplasmic reticulum (grp78) of Trypanosoma cruzi. Of the three hsp70s tested, only grp78 detected T. cruzi infection in more than 90% of nontreated (NT) patients, with cy-hsp70 and mt-hsp70 detecting only 78% and 25% of NT patients, respectively. Reactivity of leishmanial sera was 77% with cy-hsp70, 13% with grp78, and 5% with mt-hsp70. Therefore, considering sensitivity and specificity, the best candidate for T. cruzi serodiagnosis is grp78. Combination of grp78 with a T. cruzi 24-kD flagellar calcium binding protein (FCaBP) increased the diagnostic sensitivity from 90% to 97% but increased leishmanial reactivity from 3% to 8%. To determine whether hsp70s are useful for discriminating between cured and noncured patients treated with trypanocidal drugs, we tested sera from treated noncured (TNC) patients and cured patients who have positive conventional serology, termed treated dissociated (TD). The cy-hsp70 and grp78 reacted with 74% and 68% of TNC patient sera, respectively, but these antigens did not discriminate TNC from TD patients (52% and 45% positive, respectively). The mt-hsp70 was detected by sera from few TNC patients (18%) and no TD patients. Although individual hsp70s were not useful for determining the effect of trypanocidal drugs on T. cruzi infection in individual patients, the majority of TNC patient sera (70-80%) reacted with two or three of the hsp70s. In contrast, no TD sera reacted with all three hsp70s, and 40% did not react with any of the hsp70s, indicating that the number of hsp70s detected decreases following successful treatment. Considered together, these results show that grp78 has potential as a diagnostic antigen and that absence of reactivity to all three hsp70s may be indicative of effective treatment.

The complete genome sequence of the hyperthermophilic, sulphate-reducing archaeon Archaeoglobus fulgidus

Archaeoglobus fulgidus is the first sulphur-metabolizing organism to have its genome sequence determined. Its genome of 2,178,400 base pairs contains 2,436 open reading frames (ORFs). The information processing systems and the biosynthetic pathways for essential components (nucleotides, amino acids and cofactors) have extensive correlation with their counterparts in the archaeon Methanococcus jannaschii. The genomes of these two Archaea indicate dramatic differences in the way these organisms sense their environment, perform regulatory and transport functions, and gain energy. In contrast to M. jannaschii, A. fulgidus has fewer restriction-modification systems, and none of its genes appears to contain inteins. A quarter (651 ORFs) of the A. fulgidus genome encodes functionally uncharacterized yet conserved proteins, two-thirds of which are shared with M. jannaschii (428 ORFs). Another quarter of the genome encodes new proteins indicating substantial archaeal gene diversity.

The complete genome sequence of the gastric pathogen Helicobacter pylori

Helicobacter pylori, strain 26695, has a circular genome of 1,667,867 base pairs and 1,590 predicted coding sequences. Sequence analysis indicates that H. pylori has well-developed systems for motility, for scavenging iron, and for DNA restriction and modification. Many putative adhesins, lipoproteins and other outer membrane proteins were identified, underscoring the potential complexity of host-pathogen interaction. Based on the large number of sequence-related genes encoding outer membrane proteins and the presence of homopolymeric tracts and dinucleotide repeats in coding sequences, H. pylori, like several other mucosal pathogens, probably uses recombination and slipped-strand mispairing within repeats as mechanisms for antigenic variation and adaptive evolution. Consistent with its restricted niche, H. pylori has a few regulatory networks, and a limited metabolic repertoire and biosynthetic capacity. Its survival in acid conditions depends, in part, on its ability to establish a positive inside-membrane potential in low pH.

Ethanol impairs the induction of delayed hypersensitivity in C57BL/6 mice

Excessive alcohol consumption impairs T-cell-dependent immune function. Whether this impairment results from the direct inhibition of helper T (Th) cells or from inhibition of the cells that process and present antigen to Th cells is unclear. The present study examines the temporal effect of dietary alcohol on the development of delayed hypersensitivity (DTH) in C57BL/6 mice. We find that ethanol consumption just prior to and during the cognitive phase of the immune response impairs the development of a DTH response. Ethanol consumption initiated after the cognitive phase and during the effector phase of the immune response has no significant effect upon the elicitation of a DTH response. The results suggest that significant ethanol-induced impairment of DTH responses occurs during the cognitive phase of the immune response, when antigen presentation and recognition occur.

Transfer of diabetes in the NOD-scid mouse by CD4 T-cell clones. Differential requirement for CD8 T-cells

Transfer of an interleukin 2/interferon-gamma-secreting islet-specific CD4+ T-cell clone, BDC-6.9, in the immunodeficient NOD-scid mouse induces destruction of pancreatic beta-cells without help from host B-cells, CD4+ T-cells, or CD8+ T-cells. However, a second islet-specific T-cell clone, BDC-2.5, showing the same cytokine profile and T-cell receptor Vbeta expression as BDC-6.9 was not capable of inducing diabetes or insulitis in NOD-scid mice. Even though BDC-2.5 by itself readily induces diabetes in young unmanipulated NOD mice, cotransfer of CD8-enriched T-cells was required to induce disease in NOD-scid mice. Immunohistochemical staining of pancreatic lesions in young NOD mice receiving either BDC-2.5 or BDC-6.9 showed the presence of CD4+, CD8+, Vbeta4+, and MAC-1+ cells within the infiltrate, similar to infiltrates in lesions of spontaneously diabetic female NOD mice. In contrast, NOD- scid mice that received BDC-6.9 showed only the presence of CD4+Vb4+ T-cells and a large population of MAC-1+ cells in islet lesions. NOD-scid recipients of cotransferred BDC- 2.5/CD8+ splenic T-cells showed a small population of CD4+ T-cells and a larger population of CD8+ T-cells within the infiltrated islets, whereas no infiltrate was detectable in recipients of CD8+ splenocytes or BDC-2.5 alone. Our results suggest that at least two types of islet-specific CD4+ T-cell clones play a role in diabetes pathogenesis.

Inhibition of Theiler's virus-mediated demyelination by peripheral immune tolerance induction

Theiler's murine encephalomyelitis virus (TMEV), a member of the cardiovirus subfamily of the Picornaviridae, is a natural pathogen of mice. Thirty to 60 days following intracerebral infection with TMEV, susceptible inbred mouse strains develop a chronic, progressive, T cell-mediated inflammatory demyelinating disease of the central nervous system (CNS) characterized by spastic hind limb paralysis and a lifelong persistent CNS virus infection. We have examined the effect of peripheral virus-specific tolerance on the development of demyelinating disease. Treatment of SJL/J mice with TMEV-coupled, ethyl carbodiimide-treated splenocytes either before or after infection with live TMEV prevented the development of clinical disease, including inflammation and demyelination in the CNS. Prevention of clinical disease was paralleled by significant reductions in virus-specific immune responses, including delayed type hypersensitivity and T cell proliferative responses. Tolerance induction resulted in a significant reduction in the absolute numbers of mononuclear cells infiltrating the CNS, particularly the CD4+IL-2R+ T cell subset, 3, 5, and 8 wk postinfection. In contrast, tolerance induction had no effect on the numbers of CD8+IL-2R+ T cells infiltrating the CNS. Treatment with TMEV-coupled splenocytes failed to prevent the development of relapsing experimental autoimmune encephalomyelitis, demonstrating the specificity of in vivo tolerance induction. Prevention of demyelinating disease did not correlate with the increased TMEV-specific Ab responses observed in tolerized mice. These results indicate that induction of immune tolerance to TMEV can down-regulate a chronic immunopathogenic disease directed against virus Ag persisting in the CNS that normally results in a progressive demyelinating disease similar to multiple sclerosis.

Inhibition of Theiler's virus-mediated demyelination by peripheral immune tolerance induction

Theiler's murine encephalomyelitis virus (TMEV), a member of the cardiovirus subfamily of the Picornaviridae, is a natural pathogen of mice. Thirty to 60 days following intracerebral infection with TMEV, susceptible inbred mouse strains develop a chronic, progressive, T cell-mediated inflammatory demyelinating disease of the central nervous system (CNS) characterized by spastic hind limb paralysis and a lifelong persistent CNS virus infection. We have examined the effect of peripheral virus-specific tolerance on the development of demyelinating disease. Treatment of SJL/J mice with TMEV-coupled, ethyl carbodiimide-treated splenocytes either before or after infection with live TMEV prevented the development of clinical disease, including inflammation and demyelination in the CNS. Prevention of clinical disease was paralleled by significant reductions in virus-specific immune responses, including delayed type hypersensitivity and T cell proliferative responses. Tolerance induction resulted in a significant reduction in the absolute numbers of mononuclear cells infiltrating the CNS, particularly the CD4+IL-2R+ T cell subset, 3, 5, and 8 wk postinfection. In contrast, tolerance induction had no effect on the numbers of CD8+IL-2R+ T cells infiltrating the CNS. Treatment with TMEV-coupled splenocytes failed to prevent the development of relapsing experimental autoimmune encephalomyelitis, demonstrating the specificity of in vivo tolerance induction. Prevention of demyelinating disease did not correlate with the increased TMEV-specific Ab responses observed in tolerized mice. These results indicate that induction of immune tolerance to TMEV can down-regulate a chronic immunopathogenic disease directed against virus Ag persisting in the CNS that normally results in a progressive demyelinating disease similar to multiple sclerosis.

Induction of diabetes with islet-specific T-cell clones is age dependent

To investigate the effects of recipient age on the induction of diabetes by CD4+ islet-specific T-cell clones, we tested four different clones in non-obese diabetic (NOD) mice of different ages. Transfer of each of the T-cell clones resulted in insulitis and full development of diabetes in unirradiated 8-18-day-old NOD mice within 2-3 weeks. A small gender bias in disease susceptibility was seen in 8-14-day-old female NOD mice, which showed a twofold increase in disease incidence over both age-matched males and slightly older (15-18-day-old) females. In contrast, both male and female NOD mice, 19 days or older, were highly resistant to T-cell clone-induced insulitis and completely resistant to the development of diabetes. In mice of an intermediate age range (15-18 days old), two of the clones showed a three- to fourfold reduction in transfer of overt diabetes regardless of gender. These results suggest that an important developmental event occurs in both male and female NOD mice between the age of 15 and 19 days, leading to the inhibition of disease induced by T-cell clones.

Islet-specific T cell clones transfer diabetes to nonobese diabetic (NOD) F1 mice

To investigate diabetes resistance to T cell-mediated disease transfer, we administered islet-specific T cell clones to the F1 progeny of nonobese diabetic (NOD) mice that were crossed with various nondiabetes-prone inbred mouse strains. We investigated four diabetogenic CD4+ T cell clones and all induced insulitis and full development of diabetes in (SWR x NOD)F1, (SJL x NOD)F1, and (C57BL/6 x NOD)F1 mice. In contrast, (BALB/c x NOD)F1 and (CBA x NOD)F1 mice were susceptible to disease transfer by some T cell clones but not others, and (C57/L x NOD)F1 mice seemed to be resistant to both insulitis and disease transfer by all of the clones tested. Disease induced by the T cell clones in susceptible F1 strains was age dependent and could only be observed in recipients younger than 13 days old. Full or partial disease resistance did not correlate with the presence or absence of I-E, different levels of Ag expression in islet cells, or differences in APC function. The results from this study suggest that there may be multiple factors contributing to susceptibility of F1 mice to T cell clone-mediated induction of diabetes, including non-MHC-related genetic background, the immunologic maturity of the recipient, and individual characteristics of the T cell clones.

Islet-specific T cell clones transfer diabetes to nonobese diabetic (NOD) F1 mice

To investigate diabetes resistance to T cell-mediated disease transfer, we administered islet-specific T cell clones to the F1 progeny of nonobese diabetic (NOD) mice that were crossed with various nondiabetes-prone inbred mouse strains. We investigated four diabetogenic CD4+ T cell clones and all induced insulitis and full development of diabetes in (SWR x NOD)F1, (SJL x NOD)F1, and (C57BL/6 x NOD)F1 mice. In contrast, (BALB/c x NOD)F1 and (CBA x NOD)F1 mice were susceptible to disease transfer by some T cell clones but not others, and (C57/L x NOD)F1 mice seemed to be resistant to both insulitis and disease transfer by all of the clones tested. Disease induced by the T cell clones in susceptible F1 strains was age dependent and could only be observed in recipients younger than 13 days old. Full or partial disease resistance did not correlate with the presence or absence of I-E, different levels of Ag expression in islet cells, or differences in APC function. The results from this study suggest that there may be multiple factors contributing to susceptibility of F1 mice to T cell clone-mediated induction of diabetes, including non-MHC-related genetic background, the immunologic maturity of the recipient, and individual characteristics of the T cell clones.

BALB/c substrain differences in susceptibility to Theiler's murine encephalomyelitis virus-induced demyelinating disease

We report differences among BALB/c substrains in susceptibility to Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease, an immune-mediated inflammatory demyelinating disease and experimental model for human multiple sclerosis. BALB/cJ and BALB/cAnNCr mice are susceptible, while BALB/cByJ and BALB/cCum are resistant. Hybrids between BALB/cBy and BALB/cAnNCr were intermediate, although closer to the resistant parent. Backcrosses gave results compatible with differential susceptibility being related to a single segregating locus. Exposure of resistant BALB/cByJ mice to low dose irradiation, 2 days prior to infection, rendered them susceptible to TMEV-induced demyelination. The susceptibility pattern of TMEV-induced demyelinating disease among BALB/c substrains is distinct from those of several autoimmune disorders.

Anergy in vivo: down-regulation of antigen-specific CD4+ Th1 but not Th2 cytokine responses

Efficient immunologic tolerance, defined as antigen-specific unresponsiveness, can be peripherally induced by the i.v. injection of syngeneic splenocytes coupled with antigen using ethylene carbodiimide (ECDI). We have previously reported that unresponsiveness induced via i.v. injection of syngeneic splenocytes coupled with intact, UV-inactivated Theiler's murine encephalomyelitis virus (TMEV-SP) resulted in 'split tolerance'. Both virus-specific delayed-type hypersensitivity and IgG2a levels were inhibited, whereas IgG1 levels were increased when compared with sham tolerized controls. In the present report we demonstrate that tolerance induced by i.v. injection of TMEV-coupled splenocytes resulted in antigen-specific inhibition of T cell proliferation, as well as IL-2 and IFN-gamma production in response to both whole TMEV and the immunodominant viral epitope. Additionally, tolerance induction resulted in abrogation of Th1-derived [IL-2, IFN-gamma and LT/tumor necrosis factor-beta (TNF-beta)] cytokine mRNA expression in response to in vitro stimulation with UV-inactivated TMEV as determined by reverse transcriptase polymerase chain reaction. In contrast, expression of Th2-derived (IL-4, IL-6 and IL-10) cytokine mRNA was not affected in tolerized mice. Tolerance functioned directly at the level of CD4+ Th1 cells at both the induction and effector limbs as depletion of CD8+ T cells both prior to in vivo tolerization or in vitro culture had no effect on inhibition of Th1-specific responses. The mechanism of in vivo tolerance induction appeared to be anergy of CD4+ Th1 cells since IL-2, IFN-gamma and LT/TNF-beta mRNA expression as well as virus-specific proliferative responses could be restored by addition of rIL-2 to in vitro cultures of tolerant, CD4+ Th1 populations. These results suggest that in vivo 'split tolerance' induced by i.v. injection of ECDI-fixed, antigen-coupled splenocytes involves anergy of TMEV-specific, CD4+ Th1 lymphocytes and concomitant priming of Th2 cells. The induction of antigen-specific, in vivo anergy has important implications in the design of therapeutic strategies for immunopathologic diseases mediated by Th1 lymphocytes, especially T cell-mediated autoimmune disorders.

Class II-restricted T cell responses in Theiler's murine encephalomyelitis virus-induced demyelinating disease. V. Mapping of a dominant immunopathologic VP2 T cell epitope in susceptible SJL/J mice

Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease is a relevant mouse model of multiple sclerosis. Demyelination is linked to persistent TMEV infection of the central nervous system and characterized by perivascular inflammatory mononuclear infiltrates and primary demyelination. Myelin damage is a T cell-dependent process and susceptibility correlates with the temporal development of chronic virus-specific delayed-type hypersensitivity (DTH) responses. Our previous results have shown that inflammatory processes mediated by Th1 cells specific for a determinant(s) on virus capsid protein 2 (VP2) play a major immunopathologic role in SJL/J mice. This study identifies a 13 amino acid peptide on VP2 (VP2(74-86)) as the immunodominant T cell epitope in TMEV-infected and -immunized SJL/J mice, and demonstrates the ability of that sequence to prime for the majority of the SJL/J DTH T cell response to intact TMEV. The importance of T cell responses to this epitope in the demyelinating process was illustrated by experiments in which SJL/J mice displayed an increased incidence and accelerated onset of clinical disease after peripheral immunization with a fusion protein containing VP2(74-84) before intracerebral infection with a suboptimal dose of the BeAn strain of TMEV. Identification of this immunopathologic TMEV T cell epitope will be critically important for delineation of the mechanisms of T cell-mediated myelin damage and for potential use to prevent and/or treat TMEV-induced demyelinating disease via the induction of epitope-specific tolerance.

Class II-restricted T cell responses in Theiler's murine encephalomyelitis virus-induced demyelinating disease. V. Mapping of a dominant immunopathologic VP2 T cell epitope in susceptible SJL/J mice

Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease is a relevant mouse model of multiple sclerosis. Demyelination is linked to persistent TMEV infection of the central nervous system and characterized by perivascular inflammatory mononuclear infiltrates and primary demyelination. Myelin damage is a T cell-dependent process and susceptibility correlates with the temporal development of chronic virus-specific delayed-type hypersensitivity (DTH) responses. Our previous results have shown that inflammatory processes mediated by Th1 cells specific for a determinant(s) on virus capsid protein 2 (VP2) play a major immunopathologic role in SJL/J mice. This study identifies a 13 amino acid peptide on VP2 (VP2(74-86)) as the immunodominant T cell epitope in TMEV-infected and -immunized SJL/J mice, and demonstrates the ability of that sequence to prime for the majority of the SJL/J DTH T cell response to intact TMEV. The importance of T cell responses to this epitope in the demyelinating process was illustrated by experiments in which SJL/J mice displayed an increased incidence and accelerated onset of clinical disease after peripheral immunization with a fusion protein containing VP2(74-84) before intracerebral infection with a suboptimal dose of the BeAn strain of TMEV. Identification of this immunopathologic TMEV T cell epitope will be critically important for delineation of the mechanisms of T cell-mediated myelin damage and for potential use to prevent and/or treat TMEV-induced demyelinating disease via the induction of epitope-specific tolerance.

Split tolerance of Th1 and Th2 cells in tolerance to Theiler's murine encephalomyelitis virus

Theiler's murine encephalomyelitis virus (TMEV) produces a chronic, inflammatory demyelinating disease in susceptible mouse strains that is used as a model for multiple sclerosis. Because disease susceptibility correlates temporally with the development of virus-specific delayed-type hypersensitivity (DTH) responses, we studied methods and mechanisms by which virus-specific DTH could be specifically inhibited. The intravenous injection of UV-inactivated TMEV coupled to syngeneic splenocytes via a carbodiimide linkage (TMEV-SP), prior to immunization, induced a significant degree of tolerance in virus-specific helper (Th) cells as determined by decreased DTH and T cell proliferative responses, and decreased interleukin (IL)-2 and interferon (IFN)-gamma protein and mRNA levels. In contrast to the reduced levels of Th1-specific lymphokine mRNA levels, IL-4-specific mRNA levels in response to virus stimulation were not affected in tolerant mice. Surprisingly, the total anti-TMEV antibody response in DTH tolerant mice was enhanced 20-100-fold over sham-tolerized controls and was composed of reduced levels of anti-virus IgG2a, but dramatically increased levels of anti-virus IgG1. The "split-tolerance" was antigen specific, dependent on the concentrations of TMEV and carbodiimide used in the coupling procedure, and varied with the number of coupled syngeneic splenocytes administered. The fixative effects of carbodiimide on antigen-presenting function were necessary for the induction of DTH tolerance with TMEV-SP, since intravenous administration of virus coupled to splenocytes via a biotin-avidin linkage led to enhanced virus-specific antibody responses, but was unable to inhibit DTH unless concomitantly fixed with carbodiimide. Collectively, the data indicate that Th1 cells (mediating DTH, IL-2 and IFN-gamma production, and helper function for IgG2a production) were specifically anergized, with concomitant stimulation of Th2 cells (producing IL-4 and mediating helper function for IgG1 antibody production).

IgG subclass responses to Theiler's murine encephalomyelitis virus infection and immunization suggest a dominant role for Th1 cells in susceptible mouse strains

Inbred mouse strains differ in susceptibility to Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease. A strong correlation between disease susceptibility and delayed-type hypersensitivity (DTH) has been previously demonstrated, but no strong correlation between disease susceptibility and total anti-TMEV ELISA titres was shown. Since both DTH and IgG2a antibody production are regulated by CD4+ Th1 cells, we investigated three strains of mice to determine whether antivirus IgG2a antibody levels, like DTH in previous studies, correlated with disease susceptibility. Susceptible SJL/J, intermediately susceptible C3H/HeJ, and resistant C57BL/6 mice were infected intracerebrally (i.c.) with the BeAn strain of TMEV and monitored for clinical signs of demyelination and for levels of TMEV-specific antibody of different IgG subclasses using a particle concentration fluorescence immunoassay (PCFIA). Resistant C57BL/6 mice were found to have significantly lower concentrations of total anti-TMEV antibody than susceptible SJL/J mice and intermediately susceptible C3H/HeJ mice show variable antibody responses. A predominance of anti-TMEV IgG2a (Th1 regulated) antibody was seen in susceptible and intermediately susceptible mice, whereas resistant mice displayed a predominant anti-TMEV IgG1 (Th2 regulated) response accompanied by a marked deficiency of IgG2a. In contrast, immunization of C57BL/6 mice with UV-inactivated TMEV in adjuvant revealed that this strain was not defective either in its ability to generate high levels of anti-TMEV antibody or in its ability to produce IgG2a antibody. These results suggest that the antivirus IgG subclass profile is dependent upon the immunization route, virus viability and/or the use of adjuvant and that the levels of antivirus subclasses may be predictive of disease susceptibility.

Rapid biotin-avidin method for quantitation of antiviral antibody isotypes

A rapid and efficient method is described for isotype quantitation of antiviral antibodies in mice infected with Theiler's murine encephalomyelitis virus (TMEV). Serum antibodies were reacted with fluorochrome-labeled TMEV in a modified fluid-phase particle concentration fluorescence immunoassay (PCFIA). Biotin and avidin were used to attach anti-immunoglobulin isotype antibodies to polystyrene particles by the separate incubation of biotinylated goat anti-mouse isotypes (IgG1-, IgG2a-, IgG2b-, IgG3-, or IgM-specific) with avidin coupled polystyrene particles. These anti-isotype particles captured the virus-antibody complexes. Mouse myeloma proteins were used to quantitate and standardize isotype profiles of normal mouse serum using fluorescein isothiocyanate (FITC)-labeled, goat anti-mouse isotypes and polystyrene particles coated with goat anti-mouse. These assays quantitated the affinity-purified mouse serum antiviral antibodies for the standardization of antiviral isotype assays. Immunoglobulin of all serum isotypes as well as the amount of virus-specific isotypes can be quantitated rapidly and accurately.

Class II-restricted T cell responses in Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease. III. Failure of neuroantigen-specific immune tolerance to affect the clinical course of demyelination

Intracerebral inoculation of Theiler's murine encephalomyelitis virus (TMEV) into susceptible mouse strains produces a chronic demyelinating disease in which mononuclear cell-rich infiltrates in the central nervous system (CNS) are prominent. Current evidence strongly supports an immune-mediated basis for myelin breakdown, with an effector role proposed for TMEV-specific, major histocompatibility complex (MHC) class II-restricted delayed-type hypersensitivity (DTH) responses in which lymphokine-activated macrophages mediate bystander demyelination. The present study examined the possibility that concomitant or later-appearing neuroantigen-specific autoimmune T cell responses, such as those demonstrated in chronic-relapsing experimental allergic encephalomyelitis (R-EAE), may contribute to the demyelinating process following TMEV infection. T cell responses against intact, purified major myelin proteins (myelin basic protein (MBP) and proteolipid protein (PLP], and against altered myelin constituents were readily demonstrable in SJL/J mice with R-EAE, but were not detectable in SJL/J mice with TMEV-induced demyelinating disease. TMEV-infected mice also did not display T cell responses against the peptide fragments of MBP(91-104) and PLP(139-151) recently shown to be encephalitogenic in SJL/J mice. In addition, induction of neuroantigen-specific tolerance to a heterogeneous mixture of CNS antigens, via the i.v. injection of syngeneic SJL/J splenocytes covalently coupled with mouse spinal cord homogenate, resulted in significant suppression of clinical and histologic signs of R-EAE and the accompanying MBP- and PLP-specific DTH responses. In contrast, neuroantigen-specific tolerance failed to alter the development of clinical and histologic signs of TMEV-induced demyelinating disease or the accompanying virus-specific DTH and humoral immune responses. These findings demonstrate that TMEV-induced demyelinating disease can occur in the apparent absence of neuroantigen-specific autoimmune responses. The relationship of the present results to the immunopathology of multiple sclerosis is discussed.

A rapid method for quantitation of antiviral antibodies

This paper examines the parameters necessary for the efficient measurement of anti-Theiler's murine encephalomyelitis virus (TMEV) antibodies in an affinity-dependent manner using a variation of a solid-phase particle concentration fluorescence immunoassay (PCFIA). By allowing antibody to react with fluorochrome-labelled virus in fluid phase and subsequently capturing the resulting virus-antibody complexes with anti-immunoglobulin coated polystyrene particles (fluid-phase PCFIA), the present assay allows for both greater sensitivity, specificity and preservation of conformational viral epitopes than do solid-phase immunoassays. Fluid-phase PCFIA proved to be a more rapid quantitative assay than ELISA and significantly diminished non-specific binding by both untreated and heat-inactivated normal mouse sera. This methodology also allowed us to perform competition assays and to determine the dissociation kinetics of anti-viral antibody preparations, investigations which cannot generally be performed as solid-phase immunoassays. Thus fluid-phase PCFIA is a rapid and efficient immunoassay with excellent reproducibility and great versatility.

Protein thiol-disulfide interchange and interfacing with biological systems

Disulfide-containing proteins offer unique advantages for mechanistic studies of the formation of native three-dimensional structure from unordered, reduced precursors. The main advantage is that covalent intermediates are formed; by characterizing these intermediates, one obtains substantial information about the reaction pathway. Thiol-disulfide interchange is a major component of most oxidative mechanisms carrying thiol to disulfide; thus, it required some attention in its own right. Afinsen's descriptions of a "shuffle-ase" enzyme led us to examine the rates of the uncatalyzed exchange under physiologically plausible conditions. Somewhat surprisingly, we found that the rates for formation of several native proteins in uncatalyzed systems containing GSSG and GSH are as great as with the "shuffle-ase" enzyme, suggesting that a substantial portion of biological thiol oxidations proceed by uncatalyzed exchange. While thiol-disulfide exchange of course results in no net change in the oxidation level of a system, catalytic linkage of thiol or disulfide to other redox systems provides a mechanism for achieving net changes.

The amino acid sequence of the insulin from a primitive vertebrate, the atlantic hagfish (Myxine glutinosa)

Insulin has been isolated and purified from the islet organs of the cyclostome, Myxine glutinosa, by means of acid-ethanol extraction, fractional precipitation, and gel filtration. The complete amino acid sequence of the hormone has been determined by Edman degradation of the S-carboxymethylated or performic acid-oxidized A and B chains, and of various tryptic peptides derived from the chains. The 52-residue hagfish insulin has many structural features in common with other vertebrate insulins including the locations of the 6 half-cystine residues, the NH2-terminal 7 residues and the COOH-terminal 6 residues of the A chain, and several shorter sequences in the B chain that are known to comprise the dimer interface in porcine insulin crystals. Of the 24 residues which are invariant among the other known insulins, 23 are identical in hagfish int 16 of these sites it contains residues not previously observed in vertebrate insulins. The B chain also contains an additional COOH-terminal residue of methionine, making it 1 residue longer than the usual 30-residue mammalian B chains. Several features of the tertiary and quaternary structure of hagfish insulin, including the probable absence of a metal ion-stabilized hexameric form, are discussed on the basis of these findings. The results suggest that the conformation of the insulin molecule has been well conserved throughout the entire evolution of the vertebrates.

On the biosynthesis, intracellular transport and mechanism of conversion of proinsulin to insulin and C-peptide

The detailed mechanism of the enzymic transformation of proinsulin has not yet been elucidated, but it appears to be a complex process requiring the participation of several proteolytic activities. A useful model system is described in which ordinary pancreatic trypsin arid carboxypeptidase B are shown to rapidly and quantitatively convert proinsulin to insulin. This reaction is accompanied by the liberation of the C-peptide and four basic amino acids. Studies on the biosynthesis and conversion of proinsulin in isolated islets of Langerhans suggest that the conversion to insulin begins in the Golgi apparatus and continues within newly formed secretory granules. Evidence bearing on this conclusion is summarized, and experiments are described that demonstrate conversion of proinsulin to insulin in a crude secretory granule fraction prepared from islets of Langerhans. Lysates of this subcellular fraction have been shown to contain low levels of trypsin-like activity. With lightly trypsin-treated proinsulin labeled with [3H]-arginine in the regions of specific cleavage as a substrate, a carboxypeptidase B-like activity has also been detected. Further studies will be required to elucidate the nature of these enzymes and their possible relationship to the pancreatic acinar trypsins and carboxypeptidases. Structural studies on C-peptides from several mammalian species are briefly discussed. Comparisons of these amino acid sequences indicate that considerably greater interspecies variation occurs in this region of the molecule. Extension of these comparative studies of C-peptide structure should shed light on the role of this region in facilitating the correct folding of the proinsulin polypeptide chain, and these also may disclose new aspects of insulin evolution.

Risk of complications of first metatarsal head osteotomies with biodegradable pin fixation: Biofix versus Orthosorb

Bioabsorbable materials for fracture repair have recently become available in the United States. These products have been especially attractive to surgeons that perform elective foot surgeries because an additional surgery is not required to remove internal fixation, and exposed pins and their complications can be avoided. The aim of this study was to compare complications in distal first metatarsal head osteotomies fixed with Biofix, polyglycolide pins and Orthosorb, polydioxanon pins. The authors identified nine patients with 11 distal first metatarsal osteotomies repaired with Biofix and 28 patients with 34 osteotomies repaired with Orthosorb from surgery logs for a 2-year period. The authors abstracted medical records and radiographs to identify sterile sinus formation, non-unions, malunions, and osteolytic lesions. The age and gender of patients in the Orthosorb and Biofix groups were similar. Six osteotomies in five patients in the Biofix group demonstrated bone resorption and osteolytic changes involving the osteotomy. Two of these patients also had a dorsally subluxed malunion of the first metatarsal head. There was one dorsally subluxed malunion in the Orthosorb group. No sterile sinus tracts were identified in either group. Complications were more common in distal first metatarsal osteotomies fixed with Biofix compared with Orthosorb (Biofix 55%, Orthosorb 3%, p < 0.001, odds ratio: 39.6, confidence interval (CI) = 3.9-401.6). Complications in the Biofix group were significantly more common in patients 50 years of age and older (p < 0.05).