Biomedical subjects

J Böhme

Publications and source records attributed to J Böhme.

At least 19 recordsLinked to original sources

PubMed2006

[Use of the pelvic clamp in polytraumatised patients with unstable disruption of the posterior pelvic ring. Modified technique--risks--problems].

BACKGROUND: Unstable fractures of the posterior pelvic ring are frequently combined with severe hemorrhage. In 80% of cases the bleeding originates in the ruptured presacral venous plexus or the fracture itself. Arterial bleeding is less common. The pelvic clamp introduced by Ganz can make it possible to stabilise the pelvis, with subsequent compression of the fracture planes and reduction of the intrapelvic volume in such cases, so improving the prognosis. Use of the pelvic clamp can be integrated into the management in the emergency room with no problem. METHODS: This paper presents the authors' own modification of the technique for using the pelvic clamp in the emergency situation when only a clinical examination of the patient has been possible and also analyses specific problems that arise in this situation. To this end, the data relating to 29 polytraumatised patients with unstable posterior pelvic ring fractures were analysed in a retrospective study. RESULTS: In all, 8 complications were seen in 6 patients. There were 2 cases of pin malposition and 2 of over-compression of the ossa coxae and local wound problems. Secondary pin dislocation was observed in 1 case. In all these cases it was possible to correct the pelvic clamp, so that emergency stabilisation was practicable without further surgical intervention. Minor complications were found in 2 patients. These took the form of bleeding at the pin-insertion site. In 1 case an unstable transiliacal fracture was found, and in this case it was not possible to stabilise the posterior pelvic ring with the pelvic clamp. No iatrogenic lesions were detected following application of the pelvic clamp. CONCLUSION: In the hands of an experienced and practised user application of the pelvic clamp is a safe method for emergency stabilisation of the posterior pelvic ring in polytraumatised patients, even without blood volume control. Problems can be solved and do not generally mean the pelvic clamp cannot be used. The immediate radiological check (e.g. during the emergency CT -scan performed for primary diagnosis) is a must, however.

Adolescent↗

PubMed2003

Overexpression of bcl-2 in T cells affects insulitis in the nonobese diabetic mouse.

The nonobese diabetic (NOD) mouse is a useful model for human autoimmune diabetes. The gene for the anti-apoptotic protein Bcl-2 has previously been suggested as a probable susceptibility candidate for the NOD mouse disease. In this study, we investigated how overexpression of Bcl-2 in lymphocytes might affect insulitis in NOD mice. A bcl-2 transgene expressed constitutively under the SV40-promoter and the 5'Igh enhancer, Emu, was bred onto NOD background. Two bcl-2 transgenic NOD strains were produced and analysed, one with overexpression of Bcl-2 on only B cells and the other with overexpression of Bcl-2 on both B and T cells. Subsequent to verification of expression pattern and functionality of the transgene, insulitis intensity was investigated in different backcross generations of the two transgenic strains. Overexpression of Bcl-2 on both B and T cells leads to a statistically significant protection of the mice from insulitis compared with normal littermates. Overexpression of Bcl-2 on only B cells, on the other hand, does not have any statistically significant effect on insulitis. Possible mechanisms for the effect of Bcl-2 on insulitis in NOD mice are discussed.

Animals↗

PubMed2001

[The TRALI syndrome--a life-threatening transfusion reaction].

Transfusion related acute lung injury (TRALI) is a serious complication of blood transfusion, characterized by non-cardiogenic lung oedema. We describe a case of TRALI due to granulocyte-specific antibodies. The 58-year-old patient received 2 units of fresh frozen plasma following colon surgery and within 30 min the patient developed an acute respiratory distress syndrome. Granulocyte-specific antibodies were found in one of the transfused plasma of a female blood donor who most likely became immunized against granulocyte alloantigens during her three pregnancies.

Acute Disease↗

PubMed2001

Limits of peritoneal cytokine measurements during abdominal lavage treatment for intraabdominal sepsis.

BACKGROUND: Monitoring of peritoneal cytokine concentrations of tumor necrosis factor (TNF)-alpha was recommended for early detection of severe postoperative complications. In the present study the clinical application of cytokine monitoring was examined in the treatment course of severe peritonitis. METHODS: Nineteen patients with secondary peritonitis were followed up during 75 abdominal lavages. Serum and peritoneal interleukin (IL)-6, IL-8, and IL-10 and TNF-alpha were measured before the surgical intervention, after 1 hour, 3 hours, 6 hours, and 24 hours. Additionally, cardiorespiratory parameters, osmolarity, C-reactive protein, and total leucocyte count were recorded. RESULTS: Serum and peritoneal cytokine concentrations did not correlate to each other as well as to the observed cardiorespiratory parameters. Peritoneal cytokine concentrations were 10- to 1000-fold higher to serum concentrations and showed an intermittent wash out. There were no differences in determined cytokine concentrations between survivors and nonsurvivors. CONCLUSIONS: Once elevated, peritoneal cytokine measurements offer no new diagnostic or prognostic tool in abdominal lavage peritonitis treatment.

Ascitic Fluid↗

PubMed1999

DNA damage caused by etoposide and gamma-irradiation induces gene conversion of the MHC in a mouse non-germline testis cell line.

We have explored the effects of gamma-irradiation and etoposide on the gene conversion frequency between the endogenous major histocompatibility complex class II genes Abk and Ebd in a mouse testis cell line of non-germline origin with a polymerase chain reaction assay. Both gamma-rays and etoposide were shown to increase the gene conversion frequency with up to 15-fold compared to untreated cells. Etoposide, which is an agent that stabilise a cleavable complex between DNA and DNA topoisomerase II, shows an increased induction of gene conversion events with increased dose of etoposide. Cells treated with gamma-rays, which induce strand breaks, had an increased gene conversion frequency when they were subjected to low doses of irradiation, but increasing doses of irradiation did not lead to an increase of gene conversion events, which might reflect differences in the repair process depending on the extent and nature of the DNA damage. These results where DNA damage was shown to be able to induce gene conversion of endogenous genes in mouse testis cells suggests that the DNA repair system could be involved in the molecular genetic mechanism that results in gene conversion in higher eukaryotes like mammals.

Amino Acid Sequence↗

PubMed1999

E expression is needed on both bone marrow derived cells and thymic epithelium to increase IL-4 production and achieve protection in NOD bone marrow chimeras.

The NOD mouse is an animal model for insulin-dependent diabetes with many similarities to the human disease. NOD mice which are transgenic for the Ea gene, allowing expression of the E molecule, are protected from diabetes and rarely develop insulitis. We have constructed bone marrow chimeras between transgenic and non-transgenic NOD mice to study the correlation of E expression on bone marrow derived cells and thymic epithelium vs the production of IL-4 and IFN-gamma. We show that NOD-E-->NOD-E and NOD-E-->NOD chimeras have elevated levels of IL-4 compared to NOD-->NOD and NOD-->NOD-E chimeras in the thymus. However, in the periphery the protected NOD-E-->NOD-E show much higher IL-4 levels than any of the other chimeras. This drop in peripheral IL-4 production seen in NOD-E-->NOD, NOD-->NOD-E and NOD-->NOD chimeras correlates with the increased insulitis seen in these mice compared to NOD-E-->NOD-E. In contrast, there were no differences in IFN-gamma production between the chimeras. We suggest that the precommitted, regulatory T cells, selected in an E-expressing thymic environment, need continuous interaction with E-expressing primary antigen presenting cells in the periphery for optimal IL-4 production. Decrease in IL-4 production correlates with increased insulitis.

Animals↗

PubMed1999

Differential MHC expression requirements for positive selection of separate TCR Vb families.

Positive selection has been proposed to be involved in protection from diabetes. We examined positive selection by fluorescence-activated cell sorter analyses in thymocytes of protected and susceptible E-transgenic and non-transgenic NOD mice. Three Vb families showed positive selection in E-transgenic mice. Vb6(+)CD4(+) and Vb10(+)CD4(+) thymocytes were found at higher frequencies in both protected NOD-Ea and susceptible NOD-DY mice. The increased frequencies of Vb13(+)CD8(+) thymocytes were found in protected NOD-Ea mice only, and not in susceptible NOD-DY transgenic mice. These three Vb families were further examined in bone-marrow chimeras between NOD-Ea and non-transgenic NOD mice, where we could examine the contribution of E-expressing bone-marrow-derived cells in positive selection. We find that NOD-Ea-->NOD-Ea chimeras have an increased positive selection of Vb13(+)CD8(+) cells and that positive selection is more efficient when both thymic epithelium and bone-marrow-derived cells express the E molecule. This was also seen for Vb6(+)CD4(+) cells. However, for Vb6, bone-marrow-derived cells alone were also capable of positive selection. Positive selection of Vb10(+)CD4(+) cells was restricted to E-expressing thymic epithelium only. For Vb13(+)CD8(+ )cells, we found that positive selection is most efficient with E-expression on both thymic epithelium and bone-marrow-derived cells, although positive selection also occurs with E-positive epithelium only. For Vb6(+) CD4(+) cells, the dominating selecting cells are bone-marrow-derived cells, and Vb10(+)CD4(+ )cells seem to be selected exclusively by the thymic epithelium. Thus, the conditions for positive selection seem to vary considerably between different Vb families.

Animals↗

PubMed1999

Gene conversion of major histocompatibility complex genes is associated with CpG-rich regions.

We examined 32 DNA sequences of mouse and human major histocompatibility complex (MHC) genes believed to have been subjected to gene conversion events. All regions of the mouse H2 genes as well as the human HLA genes which have been implied to be involved in gene conversion events had elevated levels of CpG dinucleotides, whereas the rest of the genes showed extensive CpG suppression. Mouse MHC genes which have been suspected but not directly implied to be involved in gene conversion events also showed elevated levels of CpG dinucleotides. Moreover, both mouse and human MHC genes which have never been suspected of undergoing gene conversion had low levels of CpG throughout the genes. These results indicate that high CpG levels are correlated with gene conversion rather than with polymorphism, as non-polymorphic genes that have been implicated as gene conversion donors also have elevated levels of CpG dimers in the involved regions, whereas polymorphic genes which have never been considered to undergo gene conversion events have a low level of CpG dinucleotides. We also studied the methylation pattern of CpG dimers in the Abk gene by restriction enzyme digestion of mouse testis DNA followed by Southern blot and hybridization to an Abk-specific probe. The examined CpG dimers in prepubescent mice, where the latest germline stages are spermatogonia, leptene, or pachytene, are respectively non-methylated. Accordingly, the CpG dimers appear to be non-methylated in germline DNA from the testis of prepubescent mice, where gene conversions have been reported to occur.

Animals↗

PubMed1999

Minute defects in the expression of MHC E molecules lead to impaired protection from autoimmunity in NOD mice.

The E complex of the major histocompatibility complex (MHC) can prevent the spontaneous development of diabetes in nonobese diabetic (NOD) mice transgenic for the Ea gene. None of three promoter-mutated Ea constructs with Ea expression directed to different subsets of immunocompetent cells exerts full protection in NOD mice. The promoter-mutated constructs are all capable of mediating intrathymic elimination of I-E-restricted T cells. Thus, thymic negative selection is not responsible for the protective effect but a more complex effect is likely. Here we show that combinations of two or three different mutated Ea constructs do not protect against intra-islet insulitis either. We also show that spleen cells from protected animals are sufficient to protect NOD mice in adoptive transfer experiments. The only detectable expression defects in splenic cells or cells influencing the repertoire of splenic cells are in the B-cell compartment. Furthermore, in three construct combinations, the differences to wild-type expression are extremely small. Thus, we conclude that even minute disturbances of the E expression pattern might reduce the protection of NOD mice from insulitis.

Adoptive Transfer↗

PubMed1999

Gene conversion can create new MHC alleles.

It is possible to measure gene conversion of MHC genes with the help of a semi-nested PCR assay. Several considerations are of utmost importance when such an assay is set up. Using this assay, we have found that gene conversion occurs in MHC class II genes in mouse sperm, but not in somatic cells tested. Although this gene conversion occurs in germline cells, it is already completed in spermatogonia, and consequently is mitotic event unlinked to meiosis. The frequency of gene conversion events in MHC class II genes varies strongly from one allele to another, with the highest detected frequencies as high as 1/40,000 for an individual heterozygous for both donor and acceptor sequences. Deletions or insertions in one gene relative to the other seem to lower the efficiency of gene conversion considerably. Stretches within MHC genes amenable to gene conversion are located in CpG clusters, whereas MHC genes not involved in gene conversion have background CpG levels. DNA damage, either chemical or radiation induced, increases the frequency of gene conversion of MHC class II genes in cultured cells of the fibroblastoid lineage. The effect of chemical DNA damage seems roughly dose dependent, whereas irradiation has a maximal effect at low doses.

Alleles↗

PubMed1998

Intrachromosomal gene conversion frequency in the H2 differs between haplotypes.

We examined two intrachromosomal gene conversion events with a polymerase chain reaction assay at the DNA level between the two major histocompatibility complex class II genes Eb and Ab in mice sperm before selection has occurred. The frequency of the intrachromosomal gene conversion event between Ebd and Abd was found to be at least one order of magnitude higher than between Ebk and Abk in the same mice. Parental imprinting of the genes appears not to have an effect on gene conversion, as both (dxk)F1 and (kxd)F1 mice have indistinguishable frequencies in both haplotypes. The number of DNA copies of the donor and acceptor genes present in the cell at the time of mutation does not seem to influence the frequency of the intrachromosomal gene conversion in the k haplotype, whereas the frequency in the d haplotype is increased when double the number of donor and acceptor genes is present. The DNA fragment transferred between Ebd and Abd is invariably short, and need not comprise more than six nucleotides. The fragment transferred within the k haplotype varies in length, and can attain at least 100 nucleotides. The difference between the haplotypes both in length and frequency might be attributed to a six-nucleotide deletion in the Abk gene, which might make base-pairing between the genes less efficient and less precise.

Amino Acid Sequence↗

PubMed1998

Disease-protected major histocompatibility complex Ea-transgenic non-obese diabetic (NOD) mice show interleukin-4 production not seen in susceptible Ea-transgenic and non-transgenic NOD mice.

The non-obese diabetic (NOD) mouse is an animal model for insulin-dependent diabetes that has many similarities to the human disease. NOD mice transgenic for the Ea gene, allowing expression of the E molecule, are protected from diabetes and rarely develop insulitis. An Ea transgene mutated in the promoter region, (DeltaY) lacks E expression on most B cells, thymic medullary epithelium and primary antigen-presenting cells, and confers no protection whatsoever. We have used these transgenic NOD mice, together with non-transgenic NOD mice, to study the correlation of E expression and production of interleukin-4 (IL-4) and interferon-gamma (IFN-gamma). We show that protected E-transgenic NOD mice have elevated levels of IL-4 compared with non-transgenic mice, both in the thymus and in the periphery. However, susceptible DeltaY-transgenic mice have elevated thymic IL-4 levels, but express almost as little IL-4 as non-transgenic NOD mice in the periphery. This drop in peripheral IL-4 production seen in DeltaY-transgenic mice thus correlates with the decreased E expression in the periphery of DeltaY-transgenic NOD mice. In contrast, there were no differences in IFN-gamma production between the three NOD lines. We suggest that Ea-transgenic NOD mice have E-selected regulatory T cells producing IL-4, which are subsequently activated by E-expressing primary antigen-presenting cells in the periphery. This activation would then be instrumental for the E-mediated protection from disease in NOD mice. Such a process would explain the total absence of protection in DeltaY-transgenic NOD mice, despite their widespread E expression.

Animals↗

PubMed1997

Monokine-producing cells predominate in the recruitment phase of NOD insulitis while cells producing Th1-type cytokines characterize the effector phase.

Cells infiltrating the Langerhans' islets of prediabetic NOD females were isolated from 6 weeks to 6 months of age. These cells were assayed at a single-cell level for production of eight different cytokines by intracellular immunofluorescent staining. Quiescent in vivo preactivated cells were detected by in vitro stimulation with PMA and ionomycin for 4 h. The cell recruitment phase, between 6 and 12 weeks of age, is predominated by production of the monokines IL-1alpha, IL-6, and TNF After stimulation IFN-gamma and occasional IL-10 and GM-CSF producing cells could also be observed. This cytokine pattern occurs simultaneously with increasing insulitis, and we suggest that these cytokines are important in attracting inflammatory cells to the islets and maintaining the inflammatory state. A high frequency of endocrine cells producing IL-6 during this period may denote a stress response caused by initial beta-cell destruction due to cytokines released by the inflammatory cells. During the effector phase, between 4 and 6 months, there is a characteristic Th1 cytokine profile with lymphocytes producing IL-2, IFN-gamma and TNF, supposedly TNF-beta. No IL-4 production could be detected and IL-10 was very rarely found, indicating the absence of a Th2 response. Our findings show that the effector phase in NOD insulitis is a Th1 rather than a Th2-mediated event. We also demonstrate that cytokines that may cause initial tissue destruction are produced during the recruitment of inflammatory cells.

Aging↗

PubMed1997

Alleviation of insulitis in NOD mice is associated with expression of transgenic MHC E molecules on primary antigen-presenting cells.

Major histocompatibility complex (MHC) class II genes are important in the pathogenesis of insulin-dependent diabetes mellitus (IDDM) both in the mouse and in man. The non-obese diabetic (NOD) mouse, which is a good model for human IDDM, has a particular MHC class II with an A complex consisting of A alpha d and the unique A beta g7 chain, as well as an absent E molecule due to a deletion in the Ea promoter region. Transgenic insertion of a functional Ea gene protects against insulitis and diabetes, but when the transgene expression is restricted to certain compartments of the immune system by deleting parts of the promoter region, the protection against insulitis is disrupted. We have analysed three promoter-mutated lines where one lacks expression on B cells and has a reduced expression on approximately 1/3 of the dendritic cells and macrophages (Sma), one lacks thymic cortical expression and has a slightly reduced B-cell expression (delta X), and one lacks expression in the thymic medulla, on macrophages, dendritic cells and about half of the B cells (delta Y). None of these lines is protected against insulitis, but Sma and delta X display a reduced intensity of insulitis, with an average of 10-15% of the islets infiltrated in each mouse, while delta Y resembles non-transgenic mice with 30-35% infiltrated islets. Bone-marrow chimeras between Sma and delta Y mice demonstrate that peripheral cells of Sma origin reduce insulitis significantly when developed in the delta Y host, while insulitis is enhanced when delta Y bone marrow is given to Sma mice. This shows that E expression on the primary antigen-presenting macrophages and dendritic cells is of crucial importance to the alleviation of insulitis.

Animals↗

PubMed1997

T cells are unresponsive to transgenic MHC class II molecules expressed on pancreatic beta cells.

It has been proposed that the autoimmune attack on the pancreatic beta cells leading to insulin-dependent diabetes mellitus can be caused by the expression of MHC class II molecules on the beta cells. Transgenic mice expressing normal levels of allogeneic MHC class II Ak on the beta-cell surface (IP-Ak) do not develop either insulitis or diabetes, yet these mice are not tolerant to Ak when expressed on normal antigen-presenting cells. The authors have stimulated T cells from IP-Ak mice in vitro with Ak-expressing beta cells. Mice were also primed in vivo in order to facilitate the antiallogeneic response. The authors found that neither IP-Ak positive nor IP-Ak negative mice were able to respond to Ak-expressing beta cells, and that in vivo priming does not overcome this inability. They suggest that beta cells do not act as antigen-presenting cells, probably due to inability of delivering costimulatory signals. This strengthens the notion that MHC class II expression per se is not sufficient to induce an autoimmune attack on the beta cells.

Animals↗

PubMed1997

Gene conversion of major histocompatibility complex genes in the mouse spermatogenesis is a premeiotic event.

The molecular genetic mechanism of gene conversion in higher eukaryotes remains unknown. We find it of considerable interest to determine when during spermatogenesis gene conversion occurs. We have therefore purified pachytene spermatocytes and haploid spermatocytes from adult mice and analyzed these fractions for the presence of gene conversion products resulting from the transfer between the major histocompatibility complex class II genes Ebd and Abk in a polymerase chain reaction assay. We have further isolated spermatogenic cells from prepubescent mice and analyzed them for the presence of the same gene conversion products. We can detect gene conversion products in testis cells as early as in 8-d-old mice where the only existing spermatogenic cells are spermatogonia. The frequency of gene conversion products remains the same as the cells reach meiosis in 18-d-old mice, and is unchanged after meiosis is completed in haploid spermatocytes. Gene conversion of this specific fragment therefore appears to be a premeiotic event and, consequently, relies on genetic mechanisms other than normal meiotic recombination.

Aging↗

PubMed1997

Timing and effects of template number for gene conversion of major histocompatibility complex genes in the mouse.

Pachytene spermatocytes and haploid spermatocytes from adult mice, as well as testis cells from prepubescent mice were analysed for the presence of gene conversion products resulting from the transfer between the MHC class II genes Ebd and Abk in a PCR assay. Gene conversion products were detected in testis cells as early as in 8 days old mice, where the only existing spermatogenic cells are spermatogonia. The frequency of gene conversion products remains the same as the cells reach meiosis in 18 days old mice or in pachytene cells, and is unchanged after meiosis is completed in haploid spermatocytes, thus indicating that gene conversion is largely completed already in the mitotically dividing spermatogonia. We have furthermore analysed the frequency of gene conversion between the Eb and Ab loci within the same MHC haplotype, the k haplotype. The frequency of such events is the same in animals with one and two copies of the same haplotype, and consequently seems to be independent of template number.

Animals↗

PubMed1995

Demonstration of a TH1 cytokine profile in the late phase of NOD insulitis.

Cells infiltrating the Langerhans' islets of prediabetic NOD females were isolated from 6 weeks to 6 months of age. These cells were assayed at a single-cell level for production of eight different cytokines by intracellular immunofluorescent staining. By in vitro stimulation with PMA and ionomycin for 4 hours the method is enhanced also to detect in vivo preactivated cells. During the early phase of insulitis from 6 to 12 weeks of age, mainly the monokines IL-1 alpha, IL-6, and TNF were detected. After stimulation, also IFN-gamma and low numbers of IL-10 and GM-CSF producing cells could be observed, but no IL-2 or IL-4 was seen. This cytokine pattern correlates with an increasing insulitis, and we suggest that these cytokines are important in attracting inflammatory cells to the islets, and may cause initial beta-cell destruction. During a later phase, between 4 and 6 months, there is a characteristic TH1 cytokine profile with production of IL-2 and IFN-gamma occurring after stimulation, as well as lymphocytes producing TNF, supposedly TNF-beta. During this period IL-10 was very rarely observed, and no IL-4 production could be found throughout the study. This indicates the absence of a TH2 cytokine profile in this lesion. In addition IL-6 production occurs in high frequencies at all ages, also in endocrine islet cells. We interpret this as a stress response caused by the inflammatory lesion. Our findings show that the effector phase in NOD insulitis is TH1 rather than TH2 mediated. We also demonstrate that cytokines, that may cause initial tissue destruction, are produced during the recruitment of inflammatory cells.

Aging↗