Catechol O-methyltransferase inhibitor tolcapone has minor influence on performance in experimental memory models in rats

DNA-based immunization is a promising new technique for generating antibodies in laboratory animals for diagnostic purposes in biological science. The main advantages are the elimination of time and labor and the technically demanding steps of antigen purification. The DNA sequence of the protein of interest, cloned in a suitable in vivo expression vector that is administered intramuscularly or intradermally, is sufficient to induce an immune response in animals. We report the induction of antibodies to tobacco mosaic virus (TMV) coat protein (CP) as a highly immunogenic structural protein and potato virus Y (PVY) P1 protein (P1) as a nonstructural protein. The appropriate nucleotide sequences were introduced in a mammalian expression vector (pSG5) and injected intramuscularly into New Zealand White rabbits (Oryctolagus cuniculus). By 10 days post-injection (dpi) a specific immune response was detected against TMV-CP, while it took about 5 weeks for a response to PVY P1. In both cases the antibody titers were significantly above the corresponding pre-immune serum, however, they were considerably below the titer of the matching conventionally produced antiserum. To our knowledge, this is the first report of DNA-based immunization in order to generate antibodies to plant viral proteins, but further improvements are necessary to increase antibody titers before this promising new technique can be introduced broadly in plant science for diagnostic purposes.     

Ethical hazards of the substituted judgement test in decision making concerning the end of life of dementia patients

Previously we reported that the South American gray short-tailed opossum, Monodelphis domestica, had an MHC class-I locus similar to that of eutherian species. In addition to the detection of lymphocyte antigens by cytotoxic antisera, we concluded that this marsupial rejected allogeneic skin grafts, as would be expected of animals with MHC class-I polymorphism. However, this conclusion was based on a limited number of skin transplants that were assayed for only a short period. Here we report the results of 22 reciprocal skin grafts made between individuals of known genetic relationships. On the basis of gross inspection of the grafts and histologic examination, we found that the average time of the onset of graft rejection was about 19 days and that the average time for complete graft rejection was about 31 days. In general, it took longer for the onset of graft rejection among pairs of genetically related animals than among less related animals. These results indicate unequivocally that this marsupial species has a high degree of class-I polymorphism and rejects allogeneic skin transplants in a manner similar to but more slowly than eutherian mammals.     

Influence of biosynthetic human growth hormone on the biomechanical strength development in skin incisional wounds of diabetic rats

The influence of biosynthetic human growth hormone (b-hGH) on the mechanical strength development of skin incisional wounds in diabetic rats has been investigated after 4, 7 and 21 days of healing. Diabetes caused decreased mechanical strength of the wounds. After 21 days of healing, the diabetic animals treated with b-hGH from 7 days before wound infliction had an increased maximum load (14%) compared with the untreated diabetic animals. After 4 and 7 days of healing, no differences in the biomechanical strength of diabetic wounds with and without b-hGH treatment were found. The diabetic animals receiving b-hGH showed a significant increase in body weight compared with the untreated diabetic animals. In the diabetic animals, the blood glucose concentration was increased by treatment with b-hGH. In conclusion, treatment with b-hGH from 7 days before operation can counteract the reduced mechanical strength of skin wounds in diabetic rats on day 21.     

Tolerogenic behavior of skin allografts from neonatal mice

Neonatal skin allografts can be tolerogenic when transplanted to appropriately immunosuppressed hosts. Single grafts of neonatal skin survive longer than adult skin grafts when recipients are treated with antilymphocyte serum (ALS) and donor bone marrow cells (BMC). Neonatal skin grafts can also prolong the survival of adult grafts of the same donor strain simultaneously cotransplanted with the neonatal grafts. To probe the mechanisms involved in this cotransplantation phenomenon, we delayed placement of the neonatal cotransplants relative to grafting with adult skin. Neonatal allografts placed either 7-9 days or 14 days after grafting with adult skin significantly prolonged adult graft survival in mice treated with ALS and BMC. However, day 0-placed neonatal cotransplants must remain on the recipient for > 2 weeks to prolong adult graft survival. Removal of cotransplants from ALS- and BMC-treated recipients after 7 or 14 days abrogated the cotransplantation effect. If left in place until day 21, neonatal cotransplants could significantly prolong adult graft survival, but did not induce the long-term graft survival observed in approximately 50% of the recipients whose cotransplants were not removed. Cotransplant removal after 1 year did not affect subsequent adult graft survival. Additionally, cotransplants were removed from recipients either on day 14 or from long-term graft-bearing mice and retransplanted to other ALS/BMC-treated recipients. These retransplanted grafts were unable to prolong survival of adult grafts on the new recipients. After transplant, but not before transplant, cyclophosphamide treatment of recipients prevented expression of the cotransplant effect in ALS-treated mice. However, recipient splenectomy > or = 1 week before grafting did not interfere with the effect. These results reflect on the contributions of the donor tissue, and the recipients' response, to the tolerogenic signals that permit a neonatal cotransplant to prolong adult graft survival.     

Adoptive immunotherapy of murine lymphosarcoma: comparative study using allo-immune or tumor-immune T cells

The antitumor effect of allosensitization with lymphocytes and skin graft of DBA/2 mice was evaluated using immunogeneic, transplantable Lymphosarcoma (LS-A) syngeneic to Swiss mice. A dose dependent tumor inhibitory effect in terms of tumor free mice was observed in mice sensitized i.p. with lymphocyte doses between 10-100 million per animal. Sensitization with allogeneic primary skin graft was more effective than lymphocyte immunization. The antitumor immunity could be adoptively transferred in syngeneic Swiss mice using either allo-immune or tumor-immune T cells. Analysis of T cell phenotypes using monoclonal antibodies against cell surface markers CD4 and CD8, indicated absolute dependence on the CD4+ T cells subset in tumor cure in case of allo-immune as well as tumor-immune T cells. CD8+ T cell subset was found essential only in case of allo-immune T cell therapy. Immunosuppression of mice with whole body gamma irradiation (4 Gy), 6 hr before transfer of allo-immune or tumor-immune T cells did not abrogate the therapeutic ability of allo-immune or tumor-immune T cells. Our results suggest that allosensitization could be an effective method of generating effector lymphocyte populations that might be used to treat tumors that exhibit detectable immunogenecity.     

Accelerated (malignant) hypertension: a study of 121 cases between 1974 and 1996

DNA-based immunization is one of the most promising strategies to induce protective immunity against a variety of pathogens, presenting clear advantages as compared to the use of recombinant antigens. One of these advantages might be the ability to induce antibodies directed primarily against conformational determinants, as compared to immunization with recombinant proteins. To test this possibility, we have analyzed the antibody responses induced in mice by immunization with either recombinant soluble CD4 (rCD4) or by immunization with plasmid DNA-encoding CD4 (CD4-DNA). Mice immunized with CD4-DNA had lower titers of antibodies able to recognize rCD4 than mice immunized with rCD4. However, immunization with CD4-DNA induced antibodies reactive with the native cell surface CD4 molecule in all mice, whereas only two out of five mice immunized with rCD4 produced antibodies reactive with cell surface CD4, thus demonstrating that the genetic immunization approach may lead to an antibody response more consistent and superior at a qualitative level as compared to immunization with the corresponding recombinant protein. In addition, differences in the kinetics of appearance of antibodies directed against the native CD4 molecule were observed between mice immunized with CD4-DNA or rCD4. In the first case, antibodies reacting with cell surface CD4 were present 28 days after the first immunization, whereas mice immunized with rCD4 produced antibodies directed against the native molecule only following a booster injection. Finally, the two groups of mice produced antibodies with a different isotype distribution. No clear predominance of a specific IgG subclass was detected in the antibody population produced in response to DNA immunization. Conversely, mice immunized with rCD4 produced predominantly antibodies of the IgG1 isotype, indicating generation of a TH2 response. Together, results from this study indicate that the CD4 molecule endogenously produced following DNA immunization is expressed, at least partially, in a native conformation. This feature confers a major advantage to the DNA immunization approach as compared to immunization with the corresponding recombinant protein, which seems to elicit antibodies predominantly directed to epitopes uniquely expressed on the recombinant molecule.     

Malingering behavior in private medical practice

OBJECTIVE: This study investigated the influence of the fetal environment on the healing characteristics of adult skin. SUMMARY BACKGROUND DATA: The remarkable ability of the fetus to heal without scarring is poorly understood. The unique qualities of fetal wound healing may be caused by the fetal environment, the fetal tissues, or a combination of both. There are numerous differences between the prenatal and postnatal environments that may play a role in the unique fetal response to injury. METHODS: Full-thickness adult sheep skin was transplanted onto the backs of 60-day-gestation fetal lambs (term, 145 days of gestation). The adult skin grafts were thus perfused by fetal blood and bathed in amniotic fluid. Previous work has demonstrated that, before midgestation, fetal lambs do not reject allogenic skin grafts. Forty days later (100 days of gestation), incisional wounds were made on both the adult skin graft and the adjacent fetal skin. The wounds were harvested 14 days postwounding and analyzed by both light microscopy and immunohistochemical testing using antibodies to collagen types I, III, and VI. RESULTS: The wounds in the adult skin grafts healed with scar formation. This observation contrasts strongly with the scarless healing of the incisional fetal skin wounds. CONCLUSIONS: This study suggests that scarless fetal skin healing properties are intrinsic to fetal skin and are not primarily the result of the fetal environment.     

Comparative study of biological glues: cryoprecipitate glue, two-component fibrin sealant, and "French" glue

BACKGROUND: Although biological glues have been used clinically in cardiovascular operations, there are no comprehensive comparative studies to help clinicians select one glue over another. In this study we determined the efficacy in controlling suture line and surface bleeding and the biophysical properties of cryoprecipitate glue, two-component fibrin sealant, and "French" glue containing gelatin-resorcinol-formaldehyde-glutaraldehyde (GRFG). METHODS: Twenty-four dogs underwent a standardized atriotomy and aortotomy; the incisions were closed with interrupted 3-0 polypropylene sutures placed 3 mm apart. All dogs had a 3- by 3-cm area of the anterior wall of the right ventricle abraded until bleeding occurred. The animals were randomly allocated into four groups: in group 1 (n = 6) bleeding from the suture lines and from the epicardium was treated with cryoprecipitate glue; in group 2 (n = 6) bleeding was treated with two-component fibrin sealant; group 3 (n = 6) was treated with GRFG glue; group 4 (n = 6) was the untreated control group. The glues were also evaluated with regard to histomorphology, tensile strength, and virology. RESULTS: The cryoprecipitate glue and the two-component fibrin sealant glue were equally effective in controlling bleeding from the aortic and atrial suture lines. Although the GRFG glue slowed bleeding significantly at both sites compared to baseline, it did not provide total control. The control group required additional sutures to control bleeding. The cryoprecipitate glue and the two-component fibrin sealant provided a satisfactory clot in 3 to 4 seconds on the epicardium, whereas the GRFG glue generated a poor clot. There were minimal adhesions in the subpericardial space in the cryoprecipitate and the two-component fibrin sealant groups, whereas moderate-to-dense adhesions were present in the GRFG glue group at 6 weeks. The two-component fibrin sealant was completely reabsorbed by 10 days, but cryoprecipitate and GRFG glues were still present. On histologic examination, both fibrin glues exhibited minimal tissue reaction; in contrast, extensive fibroblastic proliferation was caused by the GRFG glue. The two-component and GRFG glues had outstanding adhesive property; in contrast, the cryoprecipitate glue did not show any adhesive power. The GRFG glue had a significantly greater tensile strength than the two-component fibrin sealant. Random samples from both cryoprecipitate and the two-component fibrin glue were free of hepatitis and retrovirus. CONCLUSIONS: The GRFG glue should be used as a tissue reinforcer; the two-component fibrin sealer is preferable when hemostatic action must be accompanied with mechanical barrier; and finally, the cryoprecipitate glue can be used when hemostatic action is the only requirement.     

Effect of cytomegalovirus on an experimental model of chronic renal allograft rejection under triple-drug treatment in the rat

BACKGROUND: Cytomegalovirus (CMV) infection is thought to be a risk factor of chronic rejection. In clinical studies and animal models, mainly concerning graft vasculopathy, CMV has been demonstrated to enhance allograft arteriosclerosis. In this study we have investigated the effect of CMV on the early inflammatory response and graft histology in an experimental model of renal transplantation in a rat strain combination that develops chronic rejection under triple-drug immunosuppression. METHODS: Renal transplantations were performed in a rat strain combination of DA-->BN receiving triple-drug treatment (2 mg/kg methylprednisolone, 2 mg/kg azathioprine, 5 mg/kg cyclosporine daily subcutaneously). One group of immunosuppressed animals was infected with rat CMV, the Maastricht strain (10(5) plaque-forming units intraperitoneally), and the other group was left uninfected. As a positive control for alloresponse, one group of recipients received neither immunosuppression nor virus. Syngenic transplantations with triple-drug treatment and CMV were used as negative controls. The grafts were monitored by frequent ultrasound-guided fine-needle aspiration biopsies, and the intragraft inflammation was quantified in detail by the increment method and expressed in corrected increment units (CIU). Graft histology was performed in parallel. RESULTS: Nonimmunosuppressed animals developed acute rejection with a high peak of inflammation (7.9+/-3.2 CIU), a typical blast response, and lymphocytosis followed by infiltration of macrophages and necrosis within 7 days. Triple drug-treated animals had a short, mild inflammatory response (3.3+/-1.4 CIU at the peak) in the graft 3-5 days after transplantation but ended up with histological changes characteristic of chronic rejection with vasculopathy and fibrosis 40-60 days later. Triple drug-treated animals with CMV demonstrated a significantly stronger inflammation (4.5+/-1.8 CIU, P<0.01) than those without, and lymphoid activation continued longer and was followed by infiltration of macrophages in the graft. CMV infection of the graft was demonstrated by viral culture and antigen detection. In histology, chronic rejection with intimal thickening of arteries and arterioles and medial necrosis of large arteries was seen at 14 days, ending up with remarkable graft fibrosis within 20 days after transplantation. CONCLUSION: CMV prolonged and increased graft inflammation and accelerated chronic rejection of renal allografts under triple-drug treatment.     

Partial protection against Plasmodium vivax blood-stage infection in Saimiri monkeys by immunization with a recombinant C-terminal fragment of merozoite surface protein 1 in block copolymer adjuvant

Merozoite surface protein 1 is a candidate for blood-stage vaccines against malaria parasites. We report here an immunization study of Saimiri monkeys with a yeast-expressed recombinant protein containing the C terminus of Plasmodium vivax merozoite surface protein 1 and two T-helper epitopes of tetanus toxin (yP2P30Pv20019), formulated in aluminum hydroxide (alum) and block copolymer P1005. Monkeys immunized three times with yP2P30Pv20019 in block copolymer P1005 had significantly higher prechallenge titers of immunoglobulin G (IgG) antibodies against the immunogen and asexual blood-stage parasites than those immunized with yP2P30Pv20019 in alum, antigen alone, or phosphate-buffered saline (PBS) (P < 0.05). Their peripheral blood mononuclear cell proliferative responses to immunogen stimulation 4 weeks after the second immunization were also significantly higher than those from the PBS control group (P < 0.05). Upon challenge with 100,000 asexual blood-stage parasites 5 weeks after the last immunization, monkeys immunized with yP2P30Pv20019 in block copolymer P1005 had prepatent periods longer than those for the control alone group (P > 0.05). Three of the five animals in this group also had low parasitemia (peak parasitemia, 相似文献   

Transient contralateral hypoglossal nerve palsy following third molar surgery under day-case general anaesthesia: a case report and review of the literature

We have noticed that bone marrow transplanted in a vascularized limb graft providing a continuous supply of donor BMC may prolong the survival time of skin graft from the same donor. The question arises whether the raised microchimerism plays a role in the prolonged survival of skin allograft. The aim of the study was to follow the development of microchimerism after allogeneic vascularized bone marrow transplantation (VBMTx) concomitantly with the rejection processes of transplanted skin. The BN rats served as donors and LEW rats as recipients of VBMTx and free skin flap allograft. Hind limb was transplanted followed by a full-thickness skin graft on the dorsum. Cellular microchimerism was investigated in recipients of VBMTx and skin grafts in blood, spleen, mesenteric lymph node and bone marrow with monoclonal antibody OX27 directed against MHC class I polymorthic RTI on BN cells and quantitatively analysed in FACStar. In VBMTx group free skin flap survived 70 days after weaning of CsA. Intravenous infusion of BMC in suspension equivalent to that grafted in hind limb did not prolong skin graft survival after cessation of CsA therapy. Donor-derived cells could be detected in VBMTx recipients as long 70 days after wearing of CsA but not in recipients of i.v. suspension BMC grafting.     

Attempts to immunize chickens with Cryptosporidium baileyi oocyst extract

In order to study the possibility of immunization against Cryptosporidium baileyi with extracted crude antigen, Arbor Acres chickens were injected intramuscularly with 80 micrograms of C. baileyi oocyst-derived proteins (uninfected immunized, UI) or inoculated orally with 8 x 10(5) viable C. baileyi oocysts (infected control, IC) at 1 wk of age. The immunization was repeated in the UI group at 2 wk of age. Uninfected (UC) birds served as controls. All animals in UI, IC, and UC groups were challenged orally with 8 x 10(5) C. baileyi oocysts at the age of 4 wk. Blood samples were collected when birds were 4 and 6 wk of age, and sera were examined by enzyme-linked immunosorbent assay for the presence of antibodies against C. baileyi. Total oocyst output of UI chickens was about 60% of that of UC birds after challenge, and the prepatent and patent periods were nearly identical in the latter 2 groups. In contrast, IC birds developed complete resistance to challenge infections. These results suggest that immunization with the oocyst extract of C. baileyi may confer some degree of protection against oral challenge; however, the protection is less effective than that induced by primary oral infection. The lack of significant difference between the antibody responses of IC and UI animals to C. baileyi at 2 wk of age suggests that serum antibodies play little role in acquired resistance to challenge infection.     

Selective suppression of antibody production with the aid of radiolabelled birch pollen allergen

In accordance with the clonal selection theory we intended to prevent the development of artificially induced birch pollen allergy in rabbits with the aid of the radiolabelled pollen allergen (75-1000 microCi125 I-pollen/animal) intravenously administered prior to pollen sensitization. The birch pollen allergen, is accordance with Burnet's working hypothesis, reacts only with a genetically determining B cell subpopulation. The fixation of the radiolabelled birch pollen allergen to the receptors of the competent B cell clone causes the lesion of the latter. Compared with the control group, this group of rabbits showed an extensive suppression of anaphylactic reagin-like PCA-antibodies, and haemagglutinating antibodies in the blood as well as in nasal secretion. In addition, we tried to influence the already ongoing synthesis of the antibodies with the aid of subsequent intravenously administered radiolabelled birch pollen allergen (750-100 microCi 125 I-pollen/animal). An intensive suppression of the synthesis of antibodies could also be proved in this case. The simultaneous immunization of the control rabbits with birch pollen and egg albumin resulted in the production of antibodies against both antigens, as expected. The hot-labelled birch pollen antigen intravenously injected before or after immunization with egg albumin and birch pollen led selectively to suppression of anti-birch-pollen PCA antibodies. The synthesis of anti-egg albumin PCA antibodies was unaffected.     

Long term evolution in Blackfan-Diamond hypoplastic anemia (author''s transl)

Hearts of newborn mice were cut into small pieces, the fragments transplanted under the ear skin of adult recipients, and the graft survival followed visually (pulsating fragments were considered viable). Donor-recipient combinations were chosen from H-2 congenic (recombinant and mutant) strains in such a way as to provide differences in the entire H-2 complex or in only a small portion of it. The data obtained indicate that a difference between the donor and the recipient in either K, D, or I regions suffices for the rejection of the heart fragments. The rejection is often accompanied by the production of antibodies against classical H-2 antigens (in the case of K- or D-region disparities) or Ia antigens (in the case of I region disparities). In some instances, the antibodies persist in the recipient for more than 50 days. We conclude from these experiments that the same loci that cause acute skin graft rejection (H-2K, H-2D, and H-2I) are responsible for heart graft rejection. Furthermore, we also conclude that serologically Ia-negative tissues may carry Ia antigens in sufficient quantities to stimulate the production of Ia antibodies.     

Effect of alignment of the transplanted graft extracellular matrix on cellular repopulation and newly synthesized collagen

This study examines the effect of alignment of the transplanted graft extracellular matrix on cellular repopulation and new collagen synthesis. The lateral half of the patellar tendon was harvested as a tendon graft from Lewis rats and frozen at -80 degrees C. In order to maintain the original alignment of the graft extracellular matrix, the graft was transplanted to a same size defect in the patellar tendon of other Lewis rats (group I). For controls, the graft was transplanted in a lax condition after excision of only the distal half of the lateral side of a patellar tendon (group II). After transplantation, six animals in each group were killed at 3, 7, 14, and 28 days. Cellular repopulation was assessed by using fibrillar-actin (F-actin) labeling with rhodamine-phalloidin, and new collagen synthesis was detected by means of a polyclonal antibody against type III collagen aminopropeptide (pN collagen III). Collagen fibril profiles were observed under the transmission electron microscope. On the 3rd day after transplantation, no specific fluorescence was detected in either group. Specific labeling for F-actin and pN collagen III, however, was observed at both ends of the graft in both groups at 1 week and throughout the graft at 2 weeks after transplantation. Consistent with the actin bundles' orientation, pN collagen III was aligned parallel to the longitudinal axis of the graft in group I. Collagen fibrils with a smaller diameter, mixed evenly and everywhere with a larger diameter, increased gradually in group I. However, smaller collagen fibrils in group II increased more slowly and were distributed unevenly. In summary, the dense collagen arrangement in the native patellar tendon determined the alignment of the repopulating cells, and the distribution of newly synthesized collagen might be affected by the actin cytoskeleton within the repopulating cells.     

Large surface of cultured human epithelium obtained on a dermal matrix based on live fibroblast-containing fibrin gels

The aim of this study was to develop a new keratinocyte culture system on a dermal equivalent suitable for skin wound closure. Our dermal matrix is based on a fibrin gel from plasma cryoprecipitate containing live human fibroblast (from human foreskin). Keratinocytes obtained from primary culture according to the Rheinwald and Green method, were seeded on the gel at different seeding ratios. In all cases, the keratinocytes plated on the dermal equivalent grew to confluence and stratified epithelium was obtained within 10-15 days in culture. Early expression of basal membrane proteins was detected by immunostaining with laminin and type IV collagen antibodies. Cell proliferation was detected both in the epidermal layer and in the fibroblast embedded in the gel as assessed by BrdU incorporation. Detachment of composite cultures from dishes or flasks is a simple and quick procedure without the need for dispase treatment. Grafting of composite cultures to nude mice gave rise to an orderly stratified, orthokeratinized epithelium resembling human epidermis. A number of advantages including a large expansion factor without the need of 3T3 feeder layer, the availability of fibrin/plasma cryoprecipitate from blood banks and the versatile manipulation of composite cultures suggest that this system could be suitable for the definitive coverage of severely burned patients.     

Split tolerance to a viral antigen expressed in thymic epithelium and keratinocytes

When expressed as a transgene from the keratin 14 (K14) promoter in an MHC class II-deficient mouse, I-Ab expressed in thymic cortical epithelium promotes positive but not negative selection of I-Ab-restricted CD4+ T cells (Laufer, T. M. et al., Nature 1996. 383:81-85). Transgenic mice expressing the E7 protein of human papilloma virus 16 from the K14 promoter were studied to determine the consequence of expression of a cytoplasmic/ nuclear protein from the K14 promoter. K14E7-transgenic mice express E7 in the thymus and skin without evidence for autoimmunity to E7. Repeated immunization of FVB(H-2q) or F1(C57BL/6JxFVB) mice with E7 elicited similar antibody responses to the defined B cell epitopes of E7 in K14E7-transgenic and non-transgenic animals. In contrast, for each genetic background, a single immunization with E7 elicited demonstrable T cell proliferative responses to the major promiscuous T helper epitope of E7 in the transgenic but not the non-transgenic animals. Further, E7-immunized non-transgenic F1 (FVBxC57BL/6J) animals developed strong E7-specific cytotoxic T lymphocyte (CTL) responses and were protected against challenge with E7+ tumors, whereas similarly immunized K14E7-transgenic animals had a markedly reduced CTL response to E7 and no E7-specific tumor protection was observed, although the antibody and CTL response to ovalbumin was normal. Expression of E7 protein as a transgene from the K14 promoter in the skin and thymus thus induces E7-specific tolerance in the cytotoxic T effector repertoire, together with expansion of the E7-specific T helper repertoire. These findings demonstrate that limited tissue distribution of an autoantigen may result in "split" tolerance to that autoantigen.     

Prevalence of asthma and wheeze in primary school children in northern Jordan

While the existence of chimeric cells in host tissue following organ transplantation is well documented, its distribution, temporal evolution and relationship to allograft survival is less clear. To explore this phenomenon, Lewis recipients of ACI cardiac allografts representing a wide range of immunosuppressive protocols and graft survival times were examined for the presence of chimerism using a sensitive polymerase chain reaction assay. Four groups of animals were examined: untransplanted animals receiving donor specific transfusion (DST)/cyclosporine A (CsA); allograft recipients with no treatment; recipients treated with DST/CsA/supplementary immunosuppression with rejection at 21-183 days; and recipients sacrificed with functioning allografts, treated with DST/CsA/supplementary immunosuppression and surviving > 200 days. To elucidate variations in the tissue distribution of chimeric cells, bone marrow, skin, liver, spleen, and thymus were examined in each animal. Untransplanted animals receiving DST/CsA displayed no evidence of chimerism. In animals receiving a cardiac allograft but no treatment, there was extensive evidence of chimerism in four of five animals. Chimerism was also detected in seven of nine animals with intermediate graft survival at the time of rejection. In animals with long-term graft survival, only four of eight displayed chimerism. These results suggest that, without immunosuppression, early chimerism does not lead to prolonged graft survival and that, even when graft survival is moderately prolonged, these cells are not sufficient to prevent rejection. In conclusion, chimerism appears to be a common phenomenon following transplantation, is not a result of DST, and may not be necessary for maintenance of long-term graft survival.     

Vaccine evaluation studies of replication-defective SIVsmB7

Non-infectious virus-like particles of SIVsmB7 that expresses env and gag gene products but are defective in pol and vpx/vpr were assessed for their ability to induce protective immunity against infection with pathogenic SIVsmE660 in rhesus macaques. Animals were immunized in three groups: group A was primed with cell-associated SIVsmB7 and boosted with cell-free SIVsmB7; group B was primed with cell-free SIVsmB7 and boosted with cell-free SIVsmB7 conjugated to iron oxide microbeads; group C was primed with cell-free SIVsmB7 mixed with Titer Max adjuvant and boosted with cell-free SIVsmB7 mixed with SAF-M adjuvant followed by secondary boosting with cell-free SIVsmB7 conjugated to microbeads. Animals were challenged intravenously with 20 animal infectious doses of SIVsmE660 grown in rhesus peripheral blood mononuclear cells 3 weeks after final boosting. All animals became infected as evidenced by quantitative virus cultivation. Sera from immunized animals contained low-titer antibodies by ELISA and low or undetectable neutralizing antibodies on the day of challenge but strong anamnestic antibody responses were observed following challenge. Interestingly, 2 of 3 animals in group A showed evidence of transient viremia and more stable CD4 counts following challenge as compared to the other immunized animals and to non-immunized controls. Thus, immunization with cell-associated SIVsmB7 did not provide sterilizing immunity against challenge with a highly pathogenic SIV strain but might have caused virus clearance later in infection.