Inflammatory, hemostatic, and clinical changes in a baboon experimental model for heatstroke.

The mortality and neurological morbidity in heatstroke have been attributed to the host's inflammatory and hemostatic responses to heat stress, suggesting that immunomodulation may improve outcome. We postulated that an experimental baboon model of heatstroke will reproduce human responses and clinical outcome to allow testing of new therapeutic strategies. Eight anesthetized juvenile baboons (Papio hamadryas) were subjected to heat stress in an incubator maintained at 44-47 degrees C until rectal temperature attained 42.5 degrees C (moderate heatstroke; n = 4) or systolic arterial pressure fell to <90 mmHg (severe heatstroke; n = 4) and were allowed to recover at room temperature. Four sham-heated animals served as a control group. Rectal temperature at the end of heat stress was 42.5 +/- 0.0 and 43.3 +/- 0.1 degrees C, respectively. All heat-stressed animals had systemic inflammation and activated coagulation, indicated by increased plasma IL-6, prothrombin time, activated partial thromboplastin time, and D-dimer levels, and decreased platelet count. Biochemical markers and/or histology evidenced cellular injury/dysfunction: plasma levels of thrombomodulin, creatinine, creatine kinase, lactic dehydrogenase, and alanine aminotransferase were increased, and varying degrees of tissue damage were present in liver, brain, and gut. No baboon with severe heatstroke survived. Neurological morbidity but no mortality was observed in baboons with moderate heatstroke. Nonsurvivors displayed significantly greater coagulopathy, inflammatory activity, and tissue injury than survivors. Sham-heated animals had an uneventful course. Heat stress elicited distinct patterns of inflammatory and hemostatic responses associated with outcome. The baboon model of heatstroke appears suitable for testing whether immunomodulation of the host's responses can improve outcome.

Correlation of antigenic expression with progress in antibiotic therapy of acute human brucellosis.

Human brucellosis is a zoonotic disease which is endemic in Saudi Arabia. The aim of this study was to investigate the humoral immune responses and identify the target antigens that persist at different stages in human brucellosis during antibiotic therapy. To do this, an acute case of accidental nosocomial infection was studied experimentally. Blood was collected from the patient at the time of diagnosis, and at weekly intervals during therapy until remission. IgG and IgM immunoblotting was used to characterize specific antigenic determinants, and ELISA antibody titration was performed to quantify the circulating antibodies. Results indicated that protein bands of 12-13.5 kDa bound IgG in the patient's sera but did not bind IgM on immunoblots and are probably not specific for, or important in, early stage infections. However, an 18 kDa band persisted during infection through remission. The pivotal and most important findings were that the number of protein bands seen on immunoblots, the magnitude of ELISA antibody titres and the concomitant changes in the intensity of the polypeptide bands of 42-43 kDa were positively correlated with the stage of infection. High numbers of anti-IgG and -IgM immunoblot bands coupled with high ELISA antibody titres and a concomitant increase in intensity of the 42-43 kDa bands were positively correlated with acute and severe infection. Conversely, a reduction in the number of polypeptide bands as well as a decrease in the intensity, until the complete disappearance of the 42-43 kDa bands, coupled with low (baseline) ELISA antibody titration values indicated successful treatment and remission. The routine use of the methods described here to ascertain the stage of the disease, assess the progress of antimicrobial therapy and monitor cases of relapse in human brucellosis is suggested.

Murine AIDS: a model for the human disease or a distinct entity?

The LP-BM5 mixture of murine retroviruses elicits a disease in mice referred to as murine immunodeficiency syndrome (MAIDS) that is considered by some to be an animal homologue of human AIDS. In this article, we present and discuss some recent findings on the pathogenesis of the murine disease and their implications for the proposed homology between murine and human syndromes. The murine disease seems to display as many similarities to as it does differences from human AIDS. Among the latter are: definitive and exclusive viral etiology, a strong genetic effect on susceptibility to infection, expansion of the CD4+ cell population in spleen and peripheral blood, consistent transmissibility by a single transfusion of the minute amounts of blood or plasma from infected donors, and striking similarity between virus-induced alteration of the in vitro spleen cell proliferation and those caused by treatment with a protein kinase inhibitor K252a. With this in mind, the use of the noncommittal term retrovirus-induced murine lymphoproliferative disease instead of MAIDS appears to be more appropriate at this time.

Acquired immunodeficiency in murine lymphoproliferative disease: considerations on pathogenesis.

C57BL/6Kh mice were infected with a single i.p. injection of 1 x 10(5) FFU of LP-BM5 MuLV. The development and progress of the virus-induced lymphoproliferative disease was followed for 12 weeks after infection. As anticipated, progressive splenomegaly and lymphadenopathy, as well as almost total abrogation of immune responsiveness ensued. In contrast to previous reports, there was a dramatic increase in the frequency of CD4+ cells in spleens among which over 20% expressed V beta 5 TCR, as compared with fewer than 3% in spleens of normal mice. Spleen cells from infected mice retained their in vitro ability to proliferate upon stimulation with IL-2 and anti-CD3, but were unable to respond when stimulated with phorbol ester and either a low dose of IL-2 or calcium ionophore (ionomycin). A similar pattern of in vitro proliferative responses was obtained when normal spleen cells were treated with K252a compound, a known inhibitor of protein kinase C activity. Together with the observations that viral infection impaired down-regulation of the phorbol-induced kinase activity and that the kinase inhibitor only marginally enhanced suppression of virus-infected cells proliferation, this finding suggests that disturbances of protein kinase C activity may underly the pathological effects seen after viral infection. However, since no apparent quantitative and qualitative changes in protein kinase C itself and its translocation were observed, it is more likely that the virus may interfere with either the substrate or product of kinase activity.

Retrovirus-induced lymphoproliferative disease in mice: role of humoral immunity in perinatally exposed mice.

The mice born to female mice infected with LP-BM5 MuLV, the etiologic agent for lymphoproliferative disease and nursed for 4-6 weeks by them were less susceptible upon reinfection by i.v. transfusion of blood or plasma from infected donors with fully developed disease. Sera of 7 week or older perinatally exposed mice were capable of a complete in vitro neutralization of virus in plasma or blood from mice with fully developed disease. In contrast, sera from 3-week old perinatally exposed mice were ineffective. The neutralizing ability of the sera was drastically reduced or abrogated after their absorption with anti-mouse IgM. These observations are consistent with the notion that perinatally exposure results ina moderate form of the disease of the offspring. This perinatal infection is followed by a production of neutralizing antibodies of predominantly the IgM class that significantly alters the course of the lymphoproliferative disease and, in some instances, even prevents its development.

Evaluation of a new device for quick sutureless coronary artery anastomosis in surviving sheep.

OBJECTIVE: A new device for performing quick sutureless vascular anastomosis by means of stent technology has recently been developed by Jomed International, Helsingborg, Sweden. The efficacy of this GraftConnector was studied in a sheep model. METHODS: In adult sheep, a left anterior thoracotomy under the fourth rib extended across the sternum gave good access to the left anterior descending branch (LAD) and the right internal mammary artery (RIMA). On beating hearts, the GraftConnector group had the RIMA connected to the LAD by means of the new device, while the control animals had the same anastomoses sutured with continuous 7-0 polypropylene sutures. The time for completing the anastomosis (ischemic time) was recorded and the blood flow in the RIMA was recorded with the proximal LAD open and closed, respectively. An intra-operative fluoroscopy with contrast injection directly into the graft was done. Finally the proximal LAD was ligated. The surviving animals are to be followed up. RESULTS: Seven (46%) of the 15 animals operated on with the traditional suturing technique and seven (63%) of the 11 GraftConnector sheep survived the procedures and are to be followed up. The 11 anastomoses done with the GraftConnector were completed in 2.41+/-0.2 min, and the 14 anastomoses sutured with continuous suture were completed in 6.93+/-0.419 min (P<0.0001). The RIMA blood-flows in the two groups were comparable and are presented. All the surviving animals had open anastomoses at fluoroscopy. CONCLUSIONS: Quick coronary artery anastomoses without suturing on beating hearts can be completed with the new GraftConnector. The GraftConnector creates reproducible anastomoses in much less time than suturing, the per-operative mortality in the GraftConnector Group was accordingly lower. Long-time follow-up of the patency in surviving animals is pending. The presented device may ultimately permit quick anastomoses endoscopically.

Effect of alcohol on spleen cells and their functions in C57BL/6 mice.

Spleen cells from C57BL/6 mice maintained on alcohol containing liquid diet for two weeks were evaluated for different immune functions. On an average, 22% fewer spleen cells were recovered from alcohol-fed mice when compared to cells from control animals. In alcohol-fed mice, the relative frequency of B cells increased, whereas total T cells including CD4+ cells decreased significantly. Alcoholic mice, when challenged with poly(rI) poly(rC), produced significantly less interferon than control mice. In vitro production of interferon alpha and gamma by the spleen cells of alcoholic mice was reduced by 67-90%. No significant differences were seen in the level of natural killer cell activity in spleen cells of control and alcoholic mice. These results suggest that chronic alcohol intake can result in not only changes in the number of immune cells, but more importantly affect their biological functions such as their ability to produce interferons.

Chronic cutaneous candidiasis in bottle-nosed dolphins.

In a 20-month period, generalized chronic cutaneous candidiasis developed in 3 performing bottle-nosed dolphins kept in an indoor pool. Extensive esophagogastric ulcerations were observed in 2 of the dolphins, each of which died, presumably because of these lesions. The 3rd dolphin died during a surgical procedure and did not have any esophagogastric ulcerations. Candida albicans was the only organism isolated from skin lesions but was not isolated from adjacent normal skin of dolphins. Treatment with antifungal drugs was unsuccessful. Subsequently, immunopotentiating treatment with levamisole phosphate resulted in formation of granulation tissue and healing of the skin lesions.

Interaction of macrophages and lymphocytes in rat skin allografts.

Light microscopy of 2 microgram sections of rejecting rat skin allografts, embedded in hydroxyethyl methacrylate, revealed among the cells infiltrating the graft base extravascular macrophages containing a small lymphocyte. Toluidine blue staining indicated DNA degradation in some of these phagocytosed lymphocytes. More frequently small lymphocytes were in intimate contact with the surface of the macrophages, resembling "Periopolesis', which others have previously observed in vitro. These macrophage-lymphocyte interactions were not seen in sections of autografts. Despite a previous report that diphenylhydantoin (phenytoin) impairs macrophage function, these macrophage-lymphocyte interactions were present in grafts placed in rats receiving this drug. This treatment did not hasten or delay the onset of graft rejection. These in vivo findings both accord with recent in vitro studies on the mechanisms of phagocytosis and with reports that phagocytosis is one of the effector mechanisms in allograft rejection. However, macrophage phagocytosis of lymphocytes has also been observed in testicular lymph collected from conscious normal sheep.

Experimental congenital syphilis: guinea pig model.

Neonates born to female guinea pigs of either a highly susceptible (C4D) or a resistant (Albany) strain, infected prior to or during pregnancy with a single dose of Treponema pallidum, showed in their sera from the first day of life immunoglobulin M (IgM) antibodies to T. pallidum, circulating immune complexes consisting of IgM antibodies and treponemal antigens, and IgM rheumatoid factor. Although the animals were asymptomatic for a 6-month observation period, several lines of evidence indicated that they were infected in utero. Molecular analysis of whole sera, purified serum IgM fraction, or dissociated immune complexes demonstrated IgM reactivity against one (47 kDa) or more of several T. pallidum peptides (15, 17, 37, 42, 45, and 87 kDa) recognized as integral membrane components. Sequential analysis of the neonates' sera by immunoblot and enzyme-linked immunosorbent assay, using alcohol-treated T. pallidum, T. phagedenis biotype Reiter, and T. vincentii, demonstrated early IgM antibodies followed 3 to 4 months later by IgG2- and IgG1-specific antibodies to T. pallidum. Moreover, an infectivity test done in five rabbits with pooled tissue extracts prepared from liveborn or stillborn animals evoked a seroconversion in two rabbits (reactive Venereal Disease Research Laboratory and fluorescent treponemal antibody tests), suggesting the presence of T. pallidum in the organs. Sera from neonates born to either T. phagedenis biotype Reiter-injected mothers or three normal pregnant females were all serologically negative. The model offers new possibilities for exploration of factors responsible for asymptomatic infection often observed in human congenital syphilis.

Studies of rabbit testes infected with Treponema pallidum. I Immunopathology.

Rabbit testes were injected with suspensions of Treponema pallidum, washed T pallidum, heat killed T pallidum, or Reiter treponemes. The testes were removed three to 24 days after injection and examined for the number of treponemes, the presence of treponemal antibodies, histopathological changes, and presence of T and B cells. In animals infected with T pallidum a substantial number (10(6)-10(7)/ml) of organisms were still present at day 24 in spite of early local production of antibodies and increasing infiltration with plasma cells, T lymphocytes, and macrophages. In animals infected with washed T pallidum a lower degree of inflammation was observed than in those infected with unmodified T pallidum, and the treponemal antibodies were detected simultaneously in samples of testicular fluid and serum. In the groups injected with heat killed T pallidum and Reiter treponemes no macroscopical or microscopical changes were detected, although in the group injected with heat killed T pallidum treponemal antibodies were detected in the testicular fluid on day 24.

Experimental syphilis: guinea pig model.

Outbred Hartley male guinea pigs (300-400 g) were infected intradermally with various concentrations of Treponema pallidum Nichols strain in the pubic region. The median lethal dose (ID50) was approximately 10(5). The animals produced lesions visible by darkfield microscopy, treponemal antibodies (IgG only), and histopathological changes in the lymphoid organs. Though less susceptible to T pallidum infection than the rabbit when infected with a sufficient number of organisms, the guinea pig may be a useful model in experimental syphilis.

Adoptive transfer of immunity to Treponema pallidum Nichols infection in inbred strain 2 and C4D guinea pigs.

T lymphocytes purified from lymph nodes and spleens of chancre-immune, inbred strain 2 guinea pigs, when infused into syngeneic guinea pigs, conferred protection against challenge with Treponema pallidum subsp. pallidum Nichols. No protection was conferred by similar injections of cell suspensions from normal guinea pigs or guinea pigs immunized with T. phagedenis biotype Reiter or T. pallidum-free testis supernatants from infected rabbits. Similar results were obtained with homozygous C4D guinea pigs. After several months of infection, 2 of 11 strain 2 and 1 of 8 strain C4D recipients of T. pallidum-immune cells developed an erythematous reaction of short duration at the injection site; 2 of these recipients were positive for T. pallidum. Throughout the experimental period the humoral response to treponemal antigens was substantially lower in the adoptively immune guinea pigs than in various unprotected control groups. Passive immunity to infection with T. pallidum, however, seems to be dose related, since asymptomatic infection persisted for as long as 3 months after challenge in strain 2 guinea pigs transfused with 10(8) T. pallidum-immune lymphocytes, but not in C4D recipients of twice as many immune cells.

Assessment of neutrophil chemotaxis and random migration in childhood. Comparison between leading-front and lower surface count methods.

Neutrophil chemotaxis and random migration were studied in 65 healthy children and 18 normal adults. The method used, the leading-front technique, was more accurate and reproducible than the lower surface count method. Chemotaxis in children under 15 years differed from that in adults. This age effect was most pronounced in those less than 6 years, and particularly in those less than 2 years. When investigating chemotaxis in childhood, comparisons with age-matched controls should be made.

Neutrophil chemotaxis and random migration in acute lymphoblastic leukaemia of childhood. Cellular and humoral aspects.

The cellular and humoral components of the neutrophil chemotactic response were studied in 65 children with acute lymphoblastic leukaemia (ALL). An abnormality in both components was found during relapse. In remission the cellular component only was affected. Although less obvious than during relapse the abnormality persisted while all cytotoxic therapy was given, returning to normal several weeks after treatment had been stopped. The absence of significant infection in relapse in this series could be due to the fact that a remisison was achieved within 3 weeks in all patients. However, a positive correlation between the migration index and incidence of bacterial infection during remission stressed the importance of impaired neutrophil chemotaxis in ALL.

Intraoral distraction osteogenesis in the baboon mandible using a tooth and bone-anchored appliance.

PURPOSE: The purpose of this study was to determine the feasibility of using an intraoral, bone and tooth-anchored appliance to distract baboon mandibles using the principles of distraction osteogenesis (DO). MATERIALS AND METHODS: Seven juvenile baboons were used in this study. Mandibular corticotomies were made in the ramus of the mandible unilaterally (n = 5) or bilaterally (n = 2), and a "pin-in-tube" (PIT) distraction appliance was applied. The device was secured to the mandibular ramus posterior to the cortical cut with a bicortical screw and anteriorly to an occlusal splint. The appliance was activated an average of 0.86 mm/d (0.5 to 1.3 mm/d) for an average of 12.4 days (10 to 14 days). Predistraction and postdistraction measurements were made between metallic markers placed in the distraction area, in the dental midline, and of the overjet and overbite. RESULTS: Bone healing was complete in all mandibles. The average mandibular lengthening measured between the metallic markers was 7.9 mm. The mandibular midlines showed an average of 4.25 mm of lateral movement in the unilaterally distracted mandibles. There were no infections. CONCLUSIONS: The results of this study indicate that an intraoral bone and tooth-anchored distraction appliance is an effective method to produce lengthening in the mandible by distraction osteogenesis.

Effect of irradiation and depletion of C3-complement component on the course of Treponema pallidum infection in a resistant guinea pig strain.

The role of complement and ionizing radiation in the natural resistance to Treponema pallidum infection of Albany guinea pigs was explored. Depletion of C3 by cobra venom factor for a period of 14 days affected neither the host's susceptibility to infection nor the humoral response. Total body irradiation with 420 or 800 R was fatal within 20-30 days and there was no multiplication of treponemes in the infected host. Animals showing lethal signs were euthanized and tissues removed for examination. Exposure to a nonlethal dose of 300 R increased the susceptibility to infection (46% symptomatic lesions) and facilitated multiplication of treponemes at the site of inoculation and in the lymphoid organs, but the humoral response was not different from that of non-irradiated controls. The results seem to suggest a defect in antigen recognition by the immunocompetent cells in the resistant Albany guinea pigs.

Experimental neonatal syphilis in a susceptible (C4D) and a resistant (Albany) strain of guinea pig.

Despite similar levels of natural antibodies and treponemicidal activity, 83% of fourth complement component-deficient (C4D) mother guinea pigs developed ulcerative lesions to a challenge of 5 x 10(7) Treponema pallidum, whereas 75% of offspring 1 to 5 days old were temporarily (2-3 months) resistant to development of dermal lesions. In contrast, only 17% of Albany-strain mothers developed small papular lesions, while 68% of 1- to 5-day-old newborns developed large papular or ulcerative lesions within 9-15 days postinfection. These findings, together with the late development of both dermal lesions and antibodies in C4D neonates, preclude the concept of an antibody-associated natural resistance. T. pallidum infection in either C4D or Albany neonates was not associated with depletion of any particular cell population in lymphoid tissue. However, marked age- and strain-dependent histologic differences were noted. Histologic examination of lymph nodes and spleens from 17-day-old and 3- to 4-month-old animals showed that maturation of lymphoid tissues in C4D animals lagged behind the Albany strain at either age. Moreover, 75% of C4D newborns contained significantly higher levels of immunomodulatory alpha 1 fetoprotein than Albany neonates. The possibility that differences in susceptibility to T. pallidum infection between C4D and Albany guinea pigs as neonates and again as adults is the result of genetically associated changes in immunologic recognition is discussed.