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Biomedical subjects

B Holm

Publications and source records attributed to B Holm.

At least 19 recordsLinked to original sources
PubMed1995

Tolerance induced by direct inoculation of donor antigen into the thymus in low and high responder rodents.

A novel approach to tolerance induction in rats was recently described where donor antigen is inoculated directly into the thymus along with a brief period of immunosuppression in a pretransplant strategy. To develop a strategy that has more clinical appeal, we evaluated the timing of donor antigen inoculation in relation to allografting, the use of frozen bone marrow as the antigen, and the dose response of purified T cells as the antigen in a low responder heterotopic heart allograft combination. Additionally, the success of this pretransplant strategy in different low and high responder strain combinations was defined. In tolerant low responder animals we evaluated in vitro and in vivo cellular immunity. Tolerant host strain naive CD8+ T cell responses to donor and third party stimulators were compared to determine if tolerance is related to the strength of the response of the T cell subsets to donor antigen. Frozen bone marrow can induce tolerance in a low responder combination. Additionally, the dose of purified T cells necessary for tolerance induction was 5 x 10(5) cells. The pretransplant strategy was successful in two low responder strain combinations, Lewis into Wistar Furth and Lewis into DA, but unsuccessful in all high responder strain combinations evaluated. Low responder animals unresponsive to donor heart allografts demonstrate intact cell-mediated immunity and donor-specific tolerance in vivo by rejecting third party but not second donor strain hearts. The in vitro responses of tolerant animals demonstrated donor-specific suppression of the MHC class II response but an intact (normal) response to third party stimulators by proliferation assays and IFN-gamma production, suggesting suppression at the CD4+ T cell subset level.

Animals↗
PubMed1995

A comparison of spontaneous versus induced tolerance in an experimental model of rat hepatic allograft transplantation.

In some rodent haplotype combinations, spontaneous tolerance (ST) develops after orthotopic liver transplantation (OLT) without any immunosuppression [e.g., Lewis (Lew, RT1) into Wistar Furth (WF, RT1u)] whereas in other combinations vigorous, progressive rejection rapidly leads to the death of the recipients. We (and others) have induced tolerance (IT) in a rejecting strain combination [Dark Agouti (DA, RT1a) into Lew] by intrathymic inoculation of donor bone marrow cells and 1 cc of antilymphocyte serum (ALS) 7-14 days prior to OLT. We hypothesized that cellular immunity in the two groups of animals was similar. We first compared survival in each group of animals and found that there was no difference in the number of animals surviving > 100 days (8/11 vs 16/17, ST vs IT, respectively, P = 0.11). Liver function studies were similar in these animals at 2 and 4 weeks after OLT and comparable to syngeneic Lew into Lew OLT animals, but significantly lower than in the rejecting DA into Lew combination treated with only ALS. Animals that were unresponsive to their allografts demonstrated donor-specific tolerance by the acceptance of donor strain (n = 4, ST and IT) and rejection of third party (n = 1 and n = 2, ST and IT groups, respectively) heterotopic heart allografts. One-way mixed lymphocyte cultures (MLC) of peripheral blood lymphocytes against donor and third party antigen were suppressed to donor and third party stimulators versus the MLC of unmanipulated animals. Naive host strain responder lymph node cells and purified T cells demonstrated strong proliferative responses to donor strain antigen in both the ST and IT animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Partial liquid ventilation in premature lambs with respiratory distress syndrome: efficacy and compatibility with exogenous surfactant.

OBJECTIVE: To determine the efficacy of partial liquid ventilation (PLV) by means of a medical-grade perfluorochemical liquid, perflubron (LiquiVent), in premature lambs with respiratory distress syndrome (RDS). Further, to determine the compatibility of perflubron with exogenous surfactant both in vitro and in vivo during PLV. DESIGN: Prospective, randomized, controlled study, with in vitro open comparison. SUBJECTS: Twenty-two premature lambs with RDS. INTERVENTIONS: In vitro assays were conducted on three exogenous surfactants before and after combination with perflubron. We studied four groups of lambs, which received one of the following treatment strategies: conventional mechanical ventilation (CMV); surfactant (Exosurf) plus CMV; PLV; or surfactant plus PLV. MEASUREMENTS AND MAIN RESULTS: In vitro surface tension, measured for three exogenous surfactants, was unchanged in each animal after exposure to perflubron. Lung mechanics and arterial blood gases were serially measured. All animals treated with PLV survived the 5 hours of experiment without complication; several animals treated with CMV died. During CMV, all animals had marked hypoxemia and hypercapnia. During PLV, arterial oxygen tension increased sixfold to sevenfold within minutes of initiation, and this increase was sustained; arterial carbon dioxide tension decreased to within the normal range. Compliance increased fourfold to fivefold during PLV compared with CMV. Tidal volumes were increased during PLV, with lower mean airway pressure. Resistance was similar for both CMV and PLV; there was no difference with surfactant treatment. CONCLUSIONS: We conclude that PLV with perflubron improves lung mechanics and gas exchange in premature lambs with RDS, that PLV is compatible with exogenous surfactant therapy, and that, as a treatment for RDS in this model, PLV is superior to the surfactant studied.

Animals↗
PubMed1995

Interferon-gamma and interleukin-10 messenger RNA are up-regulated after orthotopic liver transplantation in tolerant rats: evidence for cytokine-mediated immune dysregulation.

BACKGROUND: Immune regulation requires antigen recognition, signaling, activation, secretion of cytokines, and effector function by lymphocytes. Although there is redundancy in the activation and function of the immune response, some cytokines simultaneously promote and suppress different pathways of immunity. In the experiments reported here we compare cytokine gene expression within liver allografts from tolerant rats with normal and isografted liver tissue. We also compare the secretion of interferon-gamma (IFN-gamma) in the supernatant from mixed lymphocyte cultures by using peripheral blood lymphocytes stimulated against donor antigen. METHODS: Orthotopic liver transplantations were performed using the cuff technique without hepatic artery revascularization. Nonisotopic in situ hybridization (ISH) was used to detect and localize messenger RNA to specific cells within tissue. Antisense DNA probes were generated to interleukin-2 (IL-2), IL-4, IL-10, and IFN-gamma. One-way mixed lymphocyte cultures were set up against irradiated donor splenocytes, and the supernatant was collected to measure IFN-gamma by enzyme-linked immunosorbent assay. RESULTS: Expression of IFN-gamma and IL-10 was up-regulated in tolerant animals versus normal or isografted liver (p = 0.0002 and 0.0001, IFN-gamma and IL-10, respectively). In situ hybridization localized the expression of messenger RNA predominantly to the cytoplasm of the hepatocytes. Levels of IFN-gamma were higher in the supernatant from proliferating peripheral lymphocytes against donor antigen from tolerant animals versus naive control animals. CONCLUSIONS: Expression of IFN-gamma and IL-10 is up-regulated in hepatocytes from allograft tissue after orthotopic liver transplantation. We believe that the up-regulation of IL-10 cross-regulates the effector function of IFN-gamma and supports cytokine-mediated immune dysregulation, which may be a mechanism of tolerance after orthotopic liver transplantation in rats.

Animals↗
PubMed1994

In vivo inhibition of etoposide-mediated apoptosis, toxicity, and antitumor effect by the topoisomerase II-uncoupling anthracycline aclarubicin.

A number of clinically important drugs such as the epipodophyllotoxins etoposide (VP-16) and teniposide (VM-26), the anthracycline daunorubicin and doxorubicin (Adriamycin), and the aminoacridine amsacrine exert their cytotoxic action by stabilizing the cleavable complex formed between DNA and the nuclear enzyme topoisomerase II. We have previously demonstrated in several in vitro assays that the anthracycline aclarubicin (aclacinomycin A) inhibits cleavable-complex formation and thus antagonizes the action of drugs such as VP-16 and daunorubicin. The present study was performed to validate these in vitro data in an in vivo model. At nontoxic doses of 6 and 9 mg/kg, aclarubicin yielded a marked increase in the survival of non-tumor-bearing mice given high doses of VP-16 (80-90 mg/kg) in six separate experiments. In therapy experiments on mice inoculated with Ehrlich ascites tumor cells, aclarubicin given at 6 mg/kg roughly halved the increase in median life span induced by VP-16 at doses ranging from 22 to 33 mg/kg. An attempt to determine a more favorable combination of VP-16 and aclarubicin by increasing VP-16 doses failed, as the two drugs were always less effective than VP-16 alone. The way in which VP-16-induced DNA strand breaks lead to cell death remains unknown. However, VP-16 has been reported to cause apoptosis (programmed cell death) in several cell lines. To ascertain whether the protection given by aclarubicin could have a disruptive effect on the apoptotic process, we used the small intestine as an in vivo model. Whereas VP-16-induced apoptosis in crypt stem cells was detectable at a dose as low as 1.25 mg/kg, aclarubicin given at up to 20 mg/kg did not cause apoptosis. Indeed, aclarubicin caused a statistically significant reduction in the number of cells rendered apoptotic by VP-16. The present study thus confirms the previous in vitro experiments and indicates the value of including an in vivo model in a preclinical evaluation of drug combinations.

Aclarubicin↗
PubMed1994

Streptococcus phocae sp. nov., a new species isolated from clinical specimens from seals.

A new beta-hemolytic streptococcal species, Streptococcus phocae, was isolated from organ specimens obtained from seals. This taxon is described on the basis of the results of a study of 22 strains. S. phocae was serologically somewhat heterogeneous (group antigen -/F/C). Strains belonging to this species exhibited high levels of DNA-DNA homology to each other, as determined by DNA-DNA hybridization, but low levels of DNA-DNA homology to the type strains of other streptococcal species. A simple scheme for the differentiation of S. phocae from other beta-hemolytic streptococci is presented. Strain 8399 H1 (= NCTC 12719) is the type strain of S. phocae.

Animals↗
PubMed1993

Homogeneous antigen receptor beta-chain genes in cloned CD4- CD8- alpha beta T suppressor cells.

The rearrangements of beta-chain genes of the T cell Ag receptor were examined in 12 CD4- CD8- alpha beta + T cell lines derived from the spleen or thymus of neonatal or adult BALB/c mice. Eleven of the lines were cloned and established from six independent cloning procedures from different mice. Five cloned lines used V beta 9, four cloned lines used V beta 15, and two cloned lines used V beta 7. Nucleotide sequencing of the beta-chain genes showed that clones that used a given V beta were identically rearranged even when they were derived from independent cloning procedures. In the case of V beta 7 and V beta 15 all nucleotides in the V-D-J joining region were in the germ line configuration without N region additions. Rearrangements of the V beta 7, V beta 9, and V beta 15 genes were functional. Each V beta 15 clone also had a homogeneous rearrangement of the V beta 13 gene, which was nonfunctional. The predicted amino acid sequence of the joining regions of the V beta 7, V beta 9, and V beta 15 rearrangements showed homology in four of seven amino acids in the peptide contact region.

Animals↗
PubMed1993

Marginal tissue response adjacent to Astra Dental Implants supporting overdentures in the mandible.

The aim of this study was to evaluate the marginal tissue response adjacent to implant supported overdentures. Twenty edentulous patients had 2 Astra Dental Implants placed in the canine region of the lower jaw. New overdentures were retained by individual ball attachments in 11 patients and by a bar attachment in 9 patients. Periodontal registrations were recorded 0 months, 6 months, 12 months and 24 months after the overdentures were inserted. One of the 40 fixtures was lost at the stage of abutment connection. No fixtures were lost during the 2- to 4-year observation period and no fixtures showed any periodontal signs of failure. At the 2-year examination, no pocket depths adjacent to the implants exceeded 4 mm and no bone loss exceeded 3 mm. The mean annual bone loss was less than 0.2 mm during the first 2 years. The preliminary results from this limited study were promising and showed that two osseointegrated Astra Dental Implants could successfully retain an overdenture in the lower jaw. However, long-term observation is needed for a definitive evaluation of this treatment concept.

Aged↗
PubMed1993

Induction of tolerance to heart allografts in rats using posttransplant total lymphoid irradiation and anti-T cell antibodies.

This study examined whether posttransplant anti-T cell monoclonal or polyclonal antibody therapy could provide a window of treatment to allow posttransplant total lymphoid irradiation (TLI) to induce tolerance. These experiments were conducted in a high responder strain combination of an ACI cardiac allograft into a Lewis rat. In this situation, treatment with antibody or posttransplant TLI alone is insufficient to induce tolerance, while similar treatments alone have been shown to induce tolerance in low responder strains. The affects of three anti-T cell therapies were compared: anti-CD4 mAb therapy, anti-CD3 mAb, and rabbit antithymocyte globulin (RATG). None of these antibody therapies alone prolonged graft survival indefinitely. Combining anti-CD4 therapy with posttransplant TLI markedly delayed rejection but failed to induce long-term graft survival. Tolerance could be induced by a combination of anti-pan T cell antibody (anti-CD3) and TLI, and, all grafts survived beyond 100 days. RATG failed to prevent graft rejection when used alone or in combination with TLI. However, posttransplant therapy with a combination of RATG, TLI, and single-donor blood transfusion resulted in graft survival beyond 100 days. Recipients bearing long-term donor grafts rejected third-party (PVG) grafts within 2 weeks. Low density donor bone marrow cells used instead of a blood transfusion did not facilitate tolerance. The results indicate that monoclonal or polyclonal anti-pan T cell antibodies, TLI, and a donor blood cell infusion function synergistically in facilitating tolerance to allografts in the posttransplant period.

Animals↗
PubMed1992

Different subsets of T cells in the adult mouse bone marrow and spleen induce or suppress acute graft-versus-host disease.

Fractionation of normal adult mouse spleen and bone marrow cells (C57BL/Ka) was performed by discontinuous Percoll density gradients. The fractionated low density (1.050-1.060 g/ml) C57BL/Ka spleen cells completely suppressed acute lethal graft vs host disease (GVHD) when coinjected with unfractionated C57BL/Ka spleen cells into sublethally irradiated (400 rad) BALB/c mice. In dose response experiments, as few as 0.5 x 10(6) low density cells from the spleen fractions suppressed acute GVHD induced by 2.5 x 10(6) unfractionated allogeneic spleen cells. Although the low density spleen fractions inhibited acute GVHD, the high density (1.075-1.090 g/ml) spleen fractions induced acute GVHD in sublethally irradiated BALB/c recipients. Fractionation of C57BL/Ka bone marrow cells showed that none of the high or low density fractions or unfractionated cells induced lethal GVHD. When these fractions were tested for their capacity to suppress GVHD by coinjection with C57BL/Ka unfractionated spleen cells, all fractions protected the BALB/c recipients. Unfractionated bone marrow cells showed modest protection. Evaluation of the dose response characteristics of the suppressive activity of the low and middle density (1.060-1.068 g/ml) bone marrow cell fraction showed that reproducible protection could be achieved at a 5:1 ratio of inducing to suppressing cells. The low density fractions of both bone marrow and spleen cells had a marked depletion of typical TCR(+)-alpha beta CD4+ or CD8+ T cells, and a predominant population of TCR(+)-alpha beta CD4- CD8- T cells. Purified populations of the latter cells suppressed GVHD. Recipients given unfractionated C57BL/Ka spleen cells and protected with low-density bone marrow or spleen cells were chimeras.

Animals↗
PubMed1992

Treatment of BCL1 leukemia by transplantation of low density fractions of allogeneic bone marrow and spleen cells.

C57BL/Ka bone marrow and spleen cells fractionated by density gradients were transplanted to lethally irradiated (800 rad) BALB/c recipients. Unfractionated bone marrow and spleen cell mixtures (1:1), or high density fractions of these cells induced acute lethal graft-vs-host disease (GVHD). In contrast, low and middle density fractions of bone marrow and spleen cell mixtures reconstituted the irradiated hosts, and the majority survived for at least 100 days. The latter cells contained sufficient hemopoietic cells for reconstitution, but were deficient in inducing GVHD. Examination of the T cell subsets in the low density fractions showed a reduction of typical alpha beta TCR+ CD4+ or CD8+ cells and little change in the proportion of alpha beta TCR+ CD4- CD8- cells. BALB/c mice injected with the BCL1 B cell leukemia/lymphoma were lethally irradiated and transplanted with unfractionated BALB/c or C57BL/Ka bone marrow and spleen mixtures or low density fractions of C57BL/Ka mixtures. All control unirradiated BALB/c mice given the BCL1 tumor cells died by day 55. Almost all BALB/c mice given the BCL1 tumor cells, irradiation, and injected with a syngeneic marrow and spleen mixture died by day 95. All of the latter recipients tested showed evidence of tumor relapse. Almost all BALB/c mice given BCL1 cells, irradiation, and a C57BL/Ka unfractionated marrow and spleen mixture died by day 40. The survival of BALB/c mice given BCL1 cells, irradiation, and a low density fraction of the C57BL/Ka mixture was markedly prolonged as compared to those recipients given unfractionated allogeneic or syngeneic mixtures. None of the low density fraction recipients tested showed evidence of tumor relapse. Similar results were obtained with leukemic C57BL/Ka x BALB/c F1 hybrid mice. Thus, the low density fraction fails to induce acute lethal GVHD, but retains graft-vs-leukemia activity.

Animals↗
PubMed1992

Studies of CD4- CD8- alpha beta bone marrow T cells with suppressor activity.

The predominant T cell subset in the bone marrow of specific pathogen-free C57BL/Ka and BALB/c mice expressed the alpha beta+ TCR CD4- CD8- surface phenotype. Purified C57BL/Ka alpha beta+ TCR CD4- CD8- marrow cells obtained by cell sorting suppressed the MLR of C57BL/Ka responder and BALB/c stimulator spleen cells. Although the percentage of typical T cells in the spleen was markedly reduced in adult nude mice or normal neonatal mice as compared to the normal adult, the percentage of alpha beta+ TCR CD4- CD8- cells in the spleen and marrow was not. The percentage of "self-reactive" V beta 5+ T cells in the BALB/c spleen was markedly reduced as compared to that in the C57BL/Ka spleen. However, the percentages in the bone marrow were similar. The results indicate that the predominant subset of marrow T cells in these pathogen-free mice differ with regard to surface marker phenotype, function, dependence on the adult thymus, and deletion of certain self-reactive V beta receptors as compared to typical spleen T cells. The marrow T cells appear to develop directly from marrow precursors without rearranged beta chain genes during a 48 hour in vitro culture.

Animals↗
PubMed1992

Pathophysiology of congenital diaphragmatic hernia II: the fetal lamb CDH model is surfactant deficient.

The high mortality for congenital diaphragmatic hernia (CDH) has been attributed to a combination of pulmonary hypoplasia and pulmonary hypertension. We hypothesize that a surfactant deficiency may in part be contributing to the pathophysiology of CDH. This study documents the functional, quantitative, and qualitative aspects of the surfactant status of the alveolar air-liquid interface and the type II pneumocyte in the fetal lamb CDH model. Ten lamb fetuses (gestational age, 80 days) had a CDH created via a left thoracotomy and then were allowed to continue in utero development until term. Three litter mates and three nonoperated time-dated fetuses served as controls. At term, pressure-volume curves were performed to measure pulmonary compliance and total lung capacity. Alveolar lavage was then performed to measure the quantitative and the qualitative aspects of pulmonary surfactant. Finally, isolation of type II pneumocytes allowed quantification of phospholipid synthesis. When compared with controls (N = 6), the CDH lambs (N = 5) had significantly smaller lungs (P = .009), decreased total lung capacity (P less than .001) and compliance (P less than .001), reduced total lavaged phospholipids (P = .006), and decreased percent phosphatidylcholine (P = .02). CDH lambs also had increased total lavaged proteins (P = .05) and higher minimum dynamic surface tension (P less than .001). A surfactant deficiency may be contributing to the pathophysiology of CDH. Surfactant replacement therapy in premature infants has been shown to improve lung compliance, decrease morbidity, and improve survival. Exogenous surfactant may also benefit infants with CDH.

Animals↗
PubMed1991

Incidence and follow-up of asymptomatic multiple myeloma. The myeloma project of health region I in Norway. II.

During a general population follow-up study in Health Region I in Norway, 162 patients with multiple myeloma (MM) were diagnosed. 71 of these (44%) were asymptomatic, and were observed without chemotherapy. The great majority (90%) were in stage I, and there were only 2 with light chain disease. 45 of the 71 asymptomatic patients developed progressive disease during the 4-5 year follow-up period. Estimated median time to disease progression was 26 months. The presence at diagnosis of osteolytic lesions and/or at least 20% plasma cells in the bone marrow defined a group with significantly shorter time to progression (median 10 vs 39 months). Median survival from diagnosis for the asymptomatic patients was 45 months, which is significantly longer than the 26 months of the symptomatic group. However, when estimated from the start of treatment, the survival was similar for the two groups.

Adult↗
PubMed1990

[Factors determining the development of wound infection after appendectomy].

In order to illustrate which factors are of significance for the development of wound infection after appendectomy, an extensive prospective material of 2,097 patients submitted to appendectomy was analysed. Regression analyses demonstrated that age alone, employment of preoperative antibiotics (cefoxitin) and patient delay (time from onset of symptoms till admission) were of significance. The present authors conclude, on the basis of this material, that all patients over 25 years of age should be given preoperative antibiotic prophylaxis which covers aerobic and also anaerobic microorganisms. If a gangrenous or perforated appendix is found, antibiotics should be administered intraoperatively if prophylactic treatment has not been administered. In cases of perforation, antibiotics should be administered postoperatively for 72 hours.

Adolescent↗
PubMed1990

Cellular and molecular characteristics of transformed T cells from an antigen-specific T-cell line.

An antigen-specific T-cell line which transforms into T-lymphoma cells in vitro but apparently not in vivo is described. Membrane markers, tumorigenicity and T-cell receptor (TcR) V alpha and V beta-gene usage of the in vitro transformed T-cell line were analysed to investigate whether the transformation event was poly-, oligo-, or monoclonal. The results indicate that the T lymphoma has no chromosome abnormalities, contains no tumour-inducing virus, can induce clone-specific immunity, and is oligoclonal with respect to TcR V alpha and V beta expression. The nature of the transformation event and clinical application of vaccination against T lymphomas is discussed. In addition, the expressed TcR V alpha and V beta repertoire of Con A T blasts was apparently not affected by the Igh-l or the MHC haplotype, as investigated in Igh-l and MHC congeneic C57Bl mice.

Animals↗