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Biomedical subjects

R Zimmermann

Publications and source records attributed to R Zimmermann.

At least 271 records · Page 15Linked to original sources
PubMed1994

The relationship between size of a presecretory protein and extent of signal-recognition-particle-mediated arrest of its translation.

Small eukaryotic presecretory proteins, such as preprocecropinA, prepromelittin, and prepropeptideGLa, are transported into mammalian microsomes both with the aid of ribosome and signal recognition particle (SRP) and independently of these ribonucleoprotein particles. Typically, synthetic extensions of these precursor proteins show the phenotype of naturally occurring large presecretory proteins. However, it was shown that small truncated forms of naturally occurring large presecretory proteins are not transport competent or transport competent only in the presence of the two ribonucleoprotein particles. In order to directly address this apparent paradox, we studied the sensitivities of nascent polypeptide chains, related to preprocecropinA and prepromelittin, to SRP-mediated arrest of elongation and compared them with synthetic extensions of various length.

Animals↗
PubMed1994

The membrane proteins TRAMp and sec61 alpha p may be involved in post-translational transport of presecretory proteins into mammalian microsomes.

The presecretory protein ppcecDHFR, a hybrid between preprocecropinA and dihydrofolate reductase, is transported into mammalian microsomes post-translationally, i.e. independent of ribosome and signal recognition particle. Here, the involvement of microsomal proteins in ribonucleoparticle-independent transport of ppcecDHFR was analyzed by transport into trypsin-pretreated microsomes and by transport of a truncated version of ppcecDHFR and subsequent chemical cross-linking. We observed that post-translational transport of ppcecDHFR can occur into microsomes which had been pretreated with trypsin (final concentration, 100 micrograms/ml) and that of the known transport components only TRAMp and sec61 alpha p are still present under these conditions. Furthermore, we found that the truncated ppcecDHFR, ppcecDHFR-98mer', can be cross-linked to 36 kDa microsomal membrane proteins during post-translational transport. Therefore, the two microsomal membrane proteins with molecular masses of about 36 kDa, TRAMp and sec61 alpha p, appear to be involved in the post-translational transport of ppcecDHFR and ppcecDHFR-98mer.

Adenosine Triphosphate↗
PubMed1994

A stably folded presecretory protein associates with and upon unfolding translocates across the membrane of mammalian microsomes.

The presecretory protein ppcecDHFR, a hybrid between preprocecropin A and dihydrofolate reductase, is transported into mammalian microsomes post-translationally, i.e. independently of ribosome and signal recognition particle. Upon staging the transport process, stably folded ppcecDHFR bound to mammalian microsomes and subsequently translocated across the membrane. Membrane association depended on the signal peptide but involved neither ATP nor an N-ethylmaleimide-sensitive microsomal protein. Membrane insertion of bound ppcecDHFR did not necessitate unfolding of the DHFR domain but depended on ATP and an N-ethylmaleimide-sensitive microsomal protein. Completion of translocation relied on unfolding of the DHFR domain. Thus mammalian microsomes have the capability of transporting a bound and folded precursor protein, i.e. to trigger unfolding of a precursor protein on the membrane surface.

Adenosine Triphosphate↗
PubMed1994

Decreased expression of calmodulin mRNA in human end-stage heart failure.

Calmodulin (CaM) is the primary Ca2+ regulatory protein in cardiac cells, thus alterations in calmodulin would greatly influence the contractile response and may play a role in the abnormal calcium handling observed in human heart failure. We used Northern blot analysis to determine changes in calmodulin mRNA expression in left ventricular tissues isolated from 20 failing and four control human hearts. Only hearts with failure due to idiopathic dilated cardiomyopathy (DCM) or ischaemic heart disease (IHD) were studied. A human calmodulin cDNA probe 95% homologous to Type 3 CaM was used, which hybridized to a single 2.3 kb mRNA. CaM mRNA levels were expressed as a function of total RNA, as determined by hybridization to an 18S cDNA probe, and as a function of myocyte specific mRNA, as determined by hybridization to a myosin heavy chain (MHC) cDNA probe. In both DCM and IHD, CaM mRNA expression relative to total RNA (CaM/18S), was significantly decreased (45% and 61%, respectively) compared to control hearts. CaM mRNA expression in DCM tissues was also significantly decreased (45%) relative to myocyte specific mRNA (CaM/MHC), when compared to control hearts. In IHD, CaM mRNA was not significantly decreased in relation to myocyte specific mRNA, which suggests a greater loss of myocytes or contractile proteins in IHD as compared with DCM. The decreased expressed of CaM mRNA observed in failing hearts could affect many Ca(2+)-dependent processes, and contribute to the inability of these hearts to handle Ca2+ in a viable manner.

Adult↗
PubMed1994

[Diabetic coma with deep hypothermia. Successful resuscitation with hemofiltration].

A 41-year-old woman with severe juvenile diabetes mellitus suffered from profound hypothermia after loss of thermoregulation in diabetic ketoacidosis. She was found unconscious, without measurable blood pressure; the electrocardiogram (ECG) showed bradycardia of 30 min and the rectal temperature was 23.7 degrees C. The patient received mechanical ventilation, fluid therapy, warmed gastric lavage, and, unfortunately, inotropic medication. She was transferred to a department of cardiac surgery in order to continue the therapy with cardiopulmonary bypass (CPB). On arrival, the patient had a rectal temperature of 27.3 degrees C, the ECG showed an absolute arrhythmia with a frequency of 70/min, and the blood pressure was 63/43 mmHg. We decided to use a rapidly available but not highly invasive venovenous hemofiltration technique for slowly rewarming the patient. Vascular access was achieved by percutaneous femoral vein cannulation with a Shaldon catheter. The hemofiltration system (Gambro AK-10, Gambro AB, Sweden) was instituted with a blood flow rate of 200 ml/min. The hemofiltration monitor controls the pumps for filtering and substituting fluid volumes and allows the infusion solutions to be heated up to 40 degrees C. Sinus rhythm resumed without antiarrhythmic medications at a temperature of 29.5 degrees C, and within 8 h the patient was rewarmed to 35.5 degrees C. After treatment of the adult respiratory distress syndrome caused by pneumonia, she was discharged from the intensive care unit to complete treatment with no evidence of any permanent organ damage. We conclude that hemofiltration may be the method of choice for rewarming deeply hypothermic patients when their circulation is preserved.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

The effect of methylene blue phototreatment on plasma proteins and in vitro coagulation capability of single-donor fresh-frozen plasma.

BACKGROUND: Photodynamic virus inactivation of fresh-frozen plasma (FFP) may result in its impaired coagulation capability. STUDY DESIGN AND METHODS: Double-volume plasmapheresis samples from 11 donors were divided in pairs of 250 mL. One group underwent methylene blue (MB) phototreatment (MB-FFP). The other group was treated according to the standards of the American Association of Blood Banks for preparation and storage of FFP. Parameters of hemostasis and clinically important plasma proteins were tested in native plasma, thawed MB-FFP, thawed FFP, and twice-frozen and thawed FFP (FFP-II). RESULTS: Mean activities of factor V (73.4 vs. 94.5%; p < 0.01), factor VIII (58.1 vs. 86.7%; p < 0.001), and fibrinogen (1.8 vs. 2.8 g/L; p < 0.001) were reduced in MB-FFP as compared to those in FFP. The comparison of MB-FFP to FFP-II revealed reduced activities of factor VIII (58.1 vs. 85.2%; p < 0.001) and fibrinogen (1.8 vs. 2.8 g/L; p < 0.001) but no changes in factor V. Activated partial thromboplastin time in MB-FFP was prolonged beyond the upper normal range (+5.3 sec; p < 0.001) and prothrombin time increased in MB-FFP versus FFP (+0.96 sec; p < 0.001). CONCLUSION: MB phototreatment reduces the in vitro coagulation capacity of FFP, most likely as a result of the effects of an additional freezing and thawing procedure and photooxidation-induced protein damage.

Blood Coagulation↗
PubMed1994

[Mechanical recanalization and local thrombolysis in a patient with fulminant pulmonary embolism and craniocerebral trauma].

A 77-year-old female patient presenting with recurrent pulmonary embolism and shock had a severe craniocerebral trauma after collapsing at home 2 days before admission. Since systemic thrombolytic therapy appeared hazardous in this patient, percutaneous fragmentation and distal dispersion of the proximal pulmonary emboli was performed using a pigtail catheter. This procedure improved cardiac output immediately by 15%, whereas the mean pulmonary artery pressure dropped only slightly from 48 to 46 mmHg. Thereafter, a streptokinase infusion of 100,000 IU during 1 h was instituted through the pigtail catheter into the pulmonary artery. 12 hours after the treatment was started, cardiac output was raised by 70% and mean pulmonary artery pressure was decreased from 48 to 25 mmHg. 14 days after admission, control ventilation-perfusion scan showed a markedly improved pulmonary perfusion, and right heart catheterization revealed normal right heart pressures. The patient recovered rapidly and there was no evidence of recurrent pulmonary embolism 18 months later. This report demonstrates that a percutaneous catheter fragmentation of proximal pulmonary emboli combined with local intermediate-dose infusion of streptokinase may be a helpful therapeutic option in patients with massive pulmonary embolism in whom systemic thrombolytic therapy is contraindicated.

Aged↗
PubMed1994

Changes in gene expression following short coronary occlusions studied in porcine hearts with run-on assays.

OBJECTIVE: Brief coronary occlusions cause upregulation of expression in a wide variety of genes. These changes in tissue mRNA concentration could have been produced by transcriptional or post-transcriptional events. The aim of this study was to discriminate between increased transcription and changes in mRNA stability using run-on assays with isolated myocyte nuclei. METHODS: Myocyte nuclei isolated from ischaemic/reperfused and normal myocardium were incubated with labelled ribonucleotides. The radioactive RNA was then hybridised with specific cDNA probes and slot blots were autoradiographed. RESULTS: There was increased transcriptional activity for the proto-oncogenes c-myc, c-jun, jun-B, and jun-D. There were marked increases in transcriptional activity for sarcoplasmic Ca(2+)-ATPase, calmodulin, phospholamban, and calsequestrin. Strong transcriptional activity was found for the ubiquitin and heat shock protein (hsp27, hsp70) genes, and for PAI-1 and GAPDH. The transcription for the beta myosin heavy chain gene was not altered. CONCLUSIONS: Changes in the tissue concentration of mRNA species following brief coronary occlusion and reperfusion are most often the result of altered transcriptional activity. Increased c-fos mRNA concentrations observed in earlier studies cannot be explained by transcriptional activity of myocytes during reperfusion. Calmodulin is strongly transcribed but tissue concentration stays constant. The overall pattern of gene expression is indicative of damage at the molecular level, and calcium binding proteins (among perhaps many others) are in need of repair.

Adenosine Triphosphate↗
PubMed1994

Detection of herpesvirus type 6 by polymerase chain reaction in blood donors: random tests and prospective longitudinal studies.

In order to evaluate the prevalence of HHV-6 in blood donors, we examined 112 persons by polymerase chain reaction (PCR) and ELISA. HHV-6 antibodies could be detected in 107/111 (96.4%) of the donors. The median ELISA antibody level was 0.451 (range 0.056-0.914). 14 individuals (12.5%) were PCR positive in either oral lavage fluid, urine or buffy coat. Six persons (5.4%) were PCR positive in buffy coat samples. The prospective longitudinal analysis of 11 donors for periods between 7 and 13 weeks revealed that 4/6 persons who were initially PCR negative had positive tests in 9/63 weeks studied. Two persons were consistently PCR positive over the whole observation period of 12 and 13 weeks. HHV-6 variants could be determined in 14 persons as variant A in nine and variant B in five cases. These observations emphasize the high prevalence of HHV-6 and suggest that some blood donors carry detectable concentrations of the virus and therefore may be a source for transmission of HHV-6. The finding of positive PCR in antibody negative individuals suggests that antibody determination may not be sufficient to identify potentially infectious persons.

Antibodies, Viral↗
PubMed1994

Isotypes and IgG subclasses of anti-Fab antibodies in human immunodeficiency virus-infected hemophilia patients.

We reported recently that anti-Fab autoantibodies of the IgG isotype are associated with the decrease of helper/inducer (CD4+) lymphocytes in human immunodeficiency virus-infected (HIV+) hemophilia patients with acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC). In the present study we investigated the subclass distribution of IgG-anti-Fab autoantibodies, and whether anti-Fab antibodies of the IgA and IgM isotypes also are associated with the development of AIDS. Sera of HIV+ patients with AIDS had significantly higher IgA-anti-Fab activity than HIV+ patients with ARC (p < 0.02), HIV+ patients without AIDS/ARC (p < 0.0001), HIV-negative (HIV-) patients (p < 0.001), or healthy controls (p < 0.0001). An inverse association was found between IgA-anti-Fab activity and CD4+ cell counts (r = -0.396, p < 10(-6)). In contrast, no association of CD4+ cell counts was observed with IgM-anti-Fab. However, IgM-anti-Fab was significantly increased in patients with thrombocytopenia. We found a significant association between IgA-anti-Fab activity and serum neopterin concentrations (r = 0.310, p < 10(-5)). IgG-anti-Fab activity was detected mainly in the IgG3 fraction, although in HIV+ patients with AIDS/ARC various IgG subclasses were present. Affinity-purified anti-Fab antibodies isolated from sera of AIDS patients bound to rgp120-preincubated CD4+ cells of a healthy individual, supporting our hypothesis that anti-Fab antibodies and free circulating gp120 molecules are involved in the elimination of uninfected CD4+ cells. Removal of anti-Fab autoantibodies from the circulation by immune adsorbance might be a useful approach in the treatment of AIDS.

AIDS-Related Complex↗
PubMed1994

Microbiologic contamination of peripheral blood stem cell autografts.

We have determined the incidence and clinical significance of positive microbiologic cultures in a series of 290 peripheral blood stem cell concentrates in 95 patients undergoing multiple apheresis procedures for autologous stem cell rescue. Specimens for bacterial cultures were obtained after processing of the autografts just prior to freezing. The incidence of microbial contamination was 4.5% (n = 13). The predominant pathogenic microorganism cultured was coagulase-negative Staphylococcus (n = 11). From 8 patients with contaminated leukapheresis products 6 underwent autologous stem cell transplantation. Five patients received 1-5 culture-positive stem cell concentrates without serious sequelae, whereas the sixth patient was autografted with noncontaminated leukapheresis products, 1 concentrate contaminated with Aspergillus fumigatus being not reinfused. No microorganism present in the stem cell autograft was recovered in vivo in the posttransplantation period, although fever as a sign of infection occurred in all but 1 patient. Peripheral blood stem cell collection and ex vivo processing for cryopreservation may result in microbiologic contamination. However, our data show that infusion of contaminated stem cell autografts does not play a significant role as a source for infections in the clinical setting of autologous stem cell rescue.

Adolescent↗
PubMed1994

Identification of antibodies toward private and public class I HLA epitopes in sensitized patients.

BACKGROUND: Antibodies to HLA determinants may decrease the increment after platelet transfusion and are correlated with increased rates of rejection in renal transplantation. Cross-match tests and HLA antibody specification are used to identify compatible donors for sensitized patients. However, search for cross-match negative donors may be ineffective, and many sera containing antibodies toward public HLA epitopes give no clear results in conventional specificity analysis. MATERIALS AND METHODS: We tested a series of 4,625 sera from 1,073 patients with hematological, malignant or other diseases using a fluorescence lymphocytotoxicity test (LCT). We applied an evaluation program incorporating a list of public antigens belonging to known cross-reacting groups (CREGs) to detect antibodies toward private and just as well public epitopes. RESULTS: In 694 sera (15.0%) from 240 patients the panel reactivity (PRA) in LCT assay was higher than 5%. PRA was > or = 50% in 258 (37.2%) and < 50% in 436 sera (62.8%). In both groups we identified specific antibodies toward public HLA class I epitopes. Overall antibody specification was successful in 429 of 694 sera (61.8%) and in 175 of 240 patients (72.9%), respectively. The rate of antibodies against public epitopes shared by more than one HLA class I gene product was 203/694 (29.3%) with respect to tested sera and 83/240 (34.5%) with respect to patients. The rate of public epitope antibodies was highest in sera with PRA values from 30 to 90% showing public epitope specificity in 159 of 353 sera (45.0%). CONCLUSIONS: We conclude that antibodies toward public HLA class I determinants are detectable not only in highly sensitized patients. The described program may increase the rate of antibody specification and facilitate the platelet supply in platelet refractory patients.

Blood Grouping and Crossmatching↗
PubMed1994

HLA-DPB1 typing by PCR-SSO reverse dot blot hybridization after group-specific amplification.

BACKGROUND: The allelic diversity of HLA-DPB1 antigens can be determined at the DNA level after PCR amplification. The pattern of polymorphism at the DPB1 locus makes it difficult to unambiguously assign all genotypes in a typing system using one single pair of generic primers. MATERIALS AND METHODS: We apply here a simple technique based on the reverse dot blot analysis to the typing of HLA-DPB1 alleles. In order to increase its resolution, a group-specific amplification based on sequence variations of the polymorphic region F was used subdividing the HLA-DPB1 alleles in 2 nonoverlapping families. A separate analysis was then performed within each group of alleles. RESULTS: Using these 2 primer pairs, 21 group 1 and 30 group 2 alleles were separately amplified. From 1,378 possible allele combinations for DPB1*0101-5301 only 33 gave ambiguous typing results compared to 61 using a single pair of generic primers. CONCLUSIONS: This procedure provides a rapid and simple HLA-DPB1 genotyping. Especially in heterozygotes the hybridization patterns were easier to interpret. The utilization of group-specific amplification substantially reduced ambiguous typing results.

Alleles↗
PubMed1994

[Pregnancy after liver transplantation].

We present a case of pregnancy and delivery after liver transplantation. Even during pregnancy immunosuppression was maintained with cyclosporin (2 x 175 mg/day). The pregnancy was uneventful and there were no side effects of the cyclosporin therapy. At term we performed a cesarean section because of transverse presentation. A healthy child was born. Successful pregnancy is possible after liver transplantation, but team approach must be guaranteed.

Adult↗