Biomedical subjects

H Blum

Publications and source records attributed to H Blum.

At least 19 recordsLinked to original sources

PubMed2001

The genome of the archaeal virus SIRV1 has features in common with genomes of eukaryal viruses.

The virus SIRV1 of the extremely thermophilic archaeon Sulfolobus has a double-stranded DNA genome similar in architecture to the genomes of eukaryal viruses of the families Poxviridae, Pycodnaviridae, and Asfarviridae: the two strands of the 32,301 bp long linear genome are covalently connected forming a continuous polynucleotide chain and 2029 kb long inverted repeats are present at the termini. Very likely it also shares with these viruses mechanisms of initiation of replication and resolution of replicative intermediates.

Base Sequence↗

PubMed2001

A soluble form of the murine common gamma chain is present at high concentrations in vivo and suppresses cytokine signaling.

The common gamma-chain (gammac) is a component of the receptors for IL-2, IL-4, IL-7, IL-9, and IL-15 and is essential for their signal transduction. Western blotting and a newly established enzyme-linked immunosorbent assay detected substantial constitutive levels (50-250 ng/mL) of soluble gammac (sgammac) in sera of murine inbred strains. It was demonstrated that purified immune cells, such as T, B, and natural killer cells, and macrophages released this protein after activation. Transfection experiments with cDNA encoding the full-length gammac showed that shedding of the transmembrane receptor led to the release of sgammac. The shedding enzymes, however, appeared to be distinct from those cleaving other cytokine receptors because inhibitors of metalloproteases (eg, TAPI) did not influence sgammac release. In vivo, superantigen-induced stimulation of T cells enhanced sgammac serum concentrations up to 10-fold within 6 hours. Because these findings demonstrated regulated expression of a yet unknown molecule in the immune response, further experiments were performed to assess the possible function(s) of sgammac. A physiological role of sgammac was indicated by its capacity to specifically inhibit cell growth induced by gammac-dependent cytokines. Mutational analysis revealed that the C-terminus and the WSKWS motif are essential for the cytokine inhibitory effect of the sgammac and for binding of the molecule to cytokine receptor-expressing cells. Thus, competitive displacement of the transmembrane gammac by excess sgammac is the most likely mechanism of cell growth inhibition. It was implied that naturally produced sgammac is a negative modulator of gammac-dependent cytokines.

Amino Acid Motifs↗

PubMed2001

Toward a catalog of human genes and proteins: sequencing and analysis of 500 novel complete protein coding human cDNAs.

With the complete human genomic sequence being unraveled, the focus will shift to gene identification and to the functional analysis of gene products. The generation of a set of cDNAs, both sequences and physical clones, which contains the complete and noninterrupted protein coding regions of all human genes will provide the indispensable tools for the systematic and comprehensive analysis of protein function to eventually understand the molecular basis of man. Here we report the sequencing and analysis of 500 novel human cDNAs containing the complete protein coding frame. Assignment to functional categories was possible for 52% (259) of the encoded proteins, the remaining fraction having no similarities with known proteins. By aligning the cDNA sequences with the sequences of the finished chromosomes 21 and 22 we identified a number of genes that either had been completely missed in the analysis of the genomic sequences or had been wrongly predicted. Three of these genes appear to be present in several copies. We conclude that full-length cDNA sequencing continues to be crucial also for the accurate identification of genes. The set of 500 novel cDNAs, and another 1000 full-coding cDNAs of known transcripts we have identified, adds up to cDNA representations covering 2%--5 % of all human genes. We thus substantially contribute to the generation of a gene catalog, consisting of both full-coding cDNA sequences and clones, which should be made freely available and will become an invaluable tool for detailed functional studies.

3' Untranslated Regions↗

PubMed2000

Effect of three programmes for the treatment of endometritis on the reproductive performance of a dairy herd.

Three management programmes to improve the reproductive performance of a dairy herd were compared in a prospective controlled field study on one commercial farm. A total of 542 cows were examined for endometritis 22 to 28 days postpartum and assigned to one of three treatment groups: in group 1 the cows with signs of endometritis were treated with an intrauterine infusion of 100 ml of a 2 per cent polycondensated m-cresolsulphuric acid formaldehyde solution; in group 2 the cows with signs of endometritis were treated with an intrauterine infusion of 125 ml of a 20 per cent eucalyptus compositum solution; and in group 3 all the cows were injected intramuscularly with 0.75 mg of tiaprost, an analogue of prostaglandin F2alpha (PGF2alpha) at two-week intervals, starting on day 43, until they were inseminated. Thirty-four per cent of the cows showed signs of endometritis. In group 3, oestrus detection efficiency was significantly higher than in groups 1 and 2 (P<0.05), the interval to first service was shorter, and the cows had fewer days open than the cows in groups 1 and 2 (P<0.05). The results indicate that management programmes based on the strategic use of PGF2alpha are an effective alternative to traditional programmes based on rectal palpations and intrauterine infusions to control endometritis at a herd level.

Animal Husbandry↗

PubMed1999

Integrin antagonists.

Integrins are a family of cell surface glycoproteins that mediate numerous cell-cell and cell-matrix interactions and are involved in biological processes such as tissue morphogenesis, leukocyte recirculation and migration, wound healing, blood clotting and immune response. Aberrant cell adhesion has been implicated in the pathogenesis of several diseases, including a number of inflammatory disorders such as rheumatoid arthritis, inflammatory bowel disease and asthma, as well as cancer and coronary heart disease. As such integrins are seen as excellent targets for the development of therapeutic agents. This report begins with an examination of the structure of integrin molecules and their ligands and then goes on to review the current state of development of antiintegrin antagonists.

Animals↗

PubMed1999

High reliability of performance of well-trained rowers on a rowing ergometer.

High retest reliability is desirable in tests used to monitor athletic performance, but the reliability of many popular tests has not been established. The aim of this study was to determine the reliability of performance of a 2000-m time-trial lasting approximately 7 min performed on a Concept II rowing ergometer. Eight well-trained rowers (peak oxygen uptake 61+/-5 ml x kg(-1) x min(-1); mean +/- standard deviation) performed the time-trials on three occasions at 3-day intervals. Mean power (313+/-38 W in trial 1) improved by 2.3% (95% confidence interval 0.1 to 4.5%) in trial 2 and by a further 0.9% (-1.4 to 3.3%) in trial 3. The variability of performance for individual rowers expressed as a coefficient of variation for mean power was 2.0% (1.3 to 3.1%), and the retest correlation was 0.96 (0.87 to 0.99). Variability and changes in performance expressed as time to complete the test were approximately one-third those of mean power, apparently because simulated velocity is proportional to the cube root of power on this ergometer. Such high reliability makes this combination of ergometer, athlete and test protocol very suitable for monitoring rowing performance and for investigating factors that affect performance in short, high-intensity endurance events.

Adolescent↗

PubMed1998

Specific antagonism of type I IL-4 receptor with a mutated form of murine IL-4.

IL-4 is a pleiotropic cytokine that is essential for the differentiation of Th2 cells and is critically involved in the pathogenesis of certain infectious and allergic diseases. We have produced and functionally characterized a mutant of murine IL-4 (IL-4.Y119D) as a potential antagonist of IL-4. The analysis of IL-4R binding revealed no differences between wild-type and mutated IL-4. Despite this finding, IL-4.Y119D was unable to induce proliferation of several IL-4-responsive T cell lines mediated via the type I IL-4R (IL-4Ralpha/common gamma chain (gamma c chain)) and specifically inhibited the proliferative effect of wild-type IL-4. In contrast, with IL-4.Y119D we found induction of MHC class II and CD23 molecules on resting splenic B cells as well as proliferation of B9 plasmocytoma cells. In addition, IL-4.Y119D induced mRNA for soluble IL-4R, leading to the release of soluble IL-4R protein by spleen cells. In macrophages, mutated IL-4 in combination with IFN-gamma induced TNF-alpha-dependent killing of Leishmania major parasites such as wild-type IL-4. The agonistic effects of IL-4.Y119D were observed on cells expressing the IL-13R alpha-chain, including an IL-13R alpha-chain transfected T cell line, but were absent in T cells that lack this molecule, indicating that IL-4.Y119D conveys its activity via the type II IL-4R (IL-4Ralpha/IL-13Ralpha). The described IL-4 mutant, therefore, represents a new tool to use in dissecting different IL-4 functions that are mediated by either type I or type II IL-4R complexes.

Amino Acid Substitution↗

PubMed1998

Acclimation of photosynthesis to elevated CO2 under low-nitrogen nutrition is affected by the capacity for assimilate utilization. Perennial ryegrass under free-Air CO2 enrichment

Acclimation of photosynthesis to elevated CO2 has previously been shown to be more pronounced when N supply is poor. Is this a direct effect of N or an indirect effect of N by limiting the development of sinks for photoassimilate? This question was tested by growing a perennial ryegrass (Lolium perenne) in the field under elevated (60 Pa) and current (36 Pa) partial pressures of CO2 (pCO2) at low and high levels of N fertilization. Cutting of this herbage crop at 4- to 8-week intervals removed about 80% of the canopy, therefore decreasing the ratio of photosynthetic area to sinks for photoassimilate. Leaf photosynthesis, in vivo carboxylation capacity, carbohydrate, N, ribulose-1,5-bisphosphate carboxylase/oxygenase, sedoheptulose-1,7-bisphosphatase, and chloroplastic fructose-1, 6-bisphosphatase levels were determined for mature lamina during two consecutive summers. Just before the cut, when the canopy was relatively large, growth at elevated pCO2 and low N resulted in significant decreases in carboxylation capacity and the amount of ribulose-1,5-bisphosphate carboxylase/oxygenase protein. In high N there were no significant decreases in carboxylation capacity or proteins, but chloroplastic fructose-1,6-bisphosphatase protein levels increased significantly. Elevated pCO2 resulted in a marked and significant increase in leaf carbohydrate content at low N, but had no effect at high N. This acclimation at low N was absent after the harvest, when the canopy size was small. These results suggest that acclimation under low N is caused by limitation of sink development rather than being a direct effect of N supply on photosynthesis.

Journal Article↗

PubMed1997

Quasispecies analysis in hepatitis C virus infection by fluorescent single strand conformation polymorphism.

Hepatitis C virus (HCV) results frequently in chronic hepatitis and its sequelae liver cirrhosis and hepatocellular carcinoma. Interferon-alpha is at present the most effective treatment, resulting in a sustained response in about 20-25% of patients. HCV genotype, titer and quasispecies determine the success of treatment. In this study, fluorescent single strand conformation polymorphism (f-SSCP) was evaluated for the analysis of HCV quasispecies. Two sera from a chronically HCV-infected patient, obtained 6 years apart, were examined. The hypervariable region I (HVRI) of the HCV genome was amplified by reverse transcription and PCR. The PCR products were cloned and sequenced or fluorescein-labeled and subjected to f-SSCP. Both methods demonstrated a single HCV species in the early serum and multiple quasispecies in the late serum. Single clones of the heterogeneous virus population were used to optimize conditions for f-SSCP. The most important factors were the gel temperature and virus titer. At the optimal running temperature one base exchange in 218 bases was detectable. Repeat extractions and amplifications gave identical results. Dilution of the serum containing multiple quasispecies resulted in a 'loss' of species. Provided the running temperature is optimal and virus titer is sufficient, f-SSCP is shown to be fast and reliable for HCV quasispecies analysis.

Amino Acid Sequence↗

PubMed1997

Nucleic acid-based antiviral and gene therapy of chronic hepatitis B infection.

Persistent hepatitis B virus (HBV) infection often leads to the development of chronic hepatitis, cirrhosis and hepatocellular carcinoma. There is a need to develop new antiviral approaches for the treatment of this disease. We have explored various nucleic acid-based strategies designed to inhibit HBV replication including: the use of antisense RNA and DNA constructs, DNA-based immunization techniques to stimulate broad-based cellular immune responses with particular emphasis on the generation of cytotoxic lymphocyte (CTL) activity to viral structural proteins, hammerhead ribozymes to cleave HBV pregenomic RNA in vitro and dominant negative HBV core mutant proteins as inhibitors of nucleocapsid formation within cells. In order to optimize these antiviral effects, various novel expression vectors have been developed to deliver such DNA constructs to cells. For example, adenoviral vectors carrying genes that encode for dominant negative proteins have been employed to transfect hepatocytes in vitro and in vivo. In addition, plasmid vectors have been produced to promote expression of HBV structural genes following injection into muscle cells as a means to stimulate the host's cellular and humoral immune response in the context of histocompatibility antigen (HLA) class I and II antigen presentation. These experimental approaches may have important implications for the generation of efficient antiviral effects during chronic HBV infection.

Antiviral Agents↗

PubMed1996

Two distinct stimulus-dependent pathways lead to production of soluble murine interleukin-4 receptor.

The IL-4R exists in two forms, either membrane bound or as a soluble (s) molecule. Since the sIL-4R binds to its ligand with high affinity, thereby acting as an immunoregulatory molecule, we were interested in the processes leading to its release. First, the release of sIL-4R in the model of murine leishmaniosis was analyzed. Infection of mice with Leishmania major resulted in up-regulation of sIL-4R production by Ag-stimulated CD4+ T cells, with a maximum around 7 days after infection. To clarify the mechanisms underlying sIL-4R release, in vitro studies were performed. After stimulation of naive lymphoid cells with IL-4, sIL-4R release was dependent on up-regulation of spliced IL-4R mRNA, as shown by inhibition with specific antisense oligonucleotides. In contrast to this, no increase in the spliced IL-4R mRNA and no inhibitory influence of antisense oligonucleotides were observed after stimulation of T cells from IL-4-deficient mice with anti-CD3 mAb. Thus, TCR stimulation can lead to IL-4-independent sIL-4R production. Under these conditions proteolytic shedding of membrane-bound IL-4R appears to be the principal mechanism of release, since in contrast to stimulation with IL-4, iodinated sIL-4R could only be immunoprecipitated after cell surface labeling and subsequent TCR stimulation. The common gamma-chain, a component of the IL-4R complex, did not appear to be involved in the pathways leading to sIL-4R expression. This analysis suggests the existence of two differentially regulated pathways of sIL-4R release, possibly having different consequences for the regulation of IL-4 bioactivity.

Alternative Splicing↗

PubMed1996

Expression and co-cytokine function of murine thioredoxin/adult T cell leukaemia-derived factor (ADF).

Human ADF (adult T cell leukaemia-derived factor), an isoform of thioredoxin, promotes proliferation of certain human lymphoid cell lines and is involved in many thiol-dependent reducing reactions. To study functional aspects of the murine homologue, we established inducible overexpression of murine ADF in E. coli and a purification method which led to an apparently homogeneous 14 kDa protein. This recombinant ADF was tested in proliferation assays with murine Th2 cells (D10.G4.1) and CTLL-2 cells. In synergy with IL-2, IL-4, IL-7 and IL-9 ADF displayed co-cytokine activity. These proliferative effects were neutralized by an affinity-purified polyclonal rabbit anti-ADF antiserum. The effects of ADF were critically dependent on the presence of 2-mercaptoethanol. Bacterial thioredoxin had similar effects on the proliferation of murine T cells. Thus, the thiol-related reducing capacity of these proteins is essential for their growth promoting activity. As investigated at the levels of mRNA and protein in several murine cell clones and lines as well as in mouse tissues ADF is expressed ubiquitously. Finally it could be demonstrated by competitive PCR that in contrast to cytokine mRNAs (e.g. IL-4 and IL-13) the expression of ADF mRNA in murine Th2 clones and spleen cells is not influenced by stimulation of these cells through the T cell receptor complex. Murine ADF therefore represents a protein constitutively expressed in a wide variety of cells with the capacity to enhance the proliferative effect of several cytokines on murine T cells.

Animals↗

PubMed1996

Reversible injury: creatinine kinase recovery restores bioenergetics and function.

In postischemia hearts, cytoplasmic creatinine kinase (CK) inactivation resulting from toxic oxygen metabolite injury may lead to bioenergetic and mechanical dysfunction. This study determines the relationship between CK activity, mechanical function, and bioenergetics during reperfusion (RP) after a reversible ischemic injury. Rat hearts pretreated after 12 hr without (CTRL) or with myristic acid (MA) underwent 10 min global, 37 degrees C ischemia followed by 10 or 40 min RP while developed pressure (DP) was monitored. Catalase and CK were assayed at preischemia. CK was also assayed at end ischemia and 10 and 40 min RP. 31 P nuclear magnetic resonance spectra assessed changes in phosphocreatinine (PCr) and adenosine triphosphate (ATP) concentration. Preischemic DP was 95 +/- 5 mm Hg. CTRL DP returned to 84 +/- 3 by RP10 and 88 +/- 6 by RP40 while MA hearts recovered fully by RP10 (90 +/- 2). Preischemic catalase activity was significantly increased in MA hearts (1217 +/- 36 U/g left ventricular tissue (LV) vs 1007 +/- 40 U/g LV, P < 0.01, MA vs CTRL). CTRL CK activity fell from 1870 +/- 75 to 1103 +/- 11 U/g LV at RP10, but rose to 1272 +/- 13 by RP40 (P < 0.01, RP10 vs RP40). MA hearts lost no CK activity during RP. By RP10, CTRL PCr/ATP ratio was elevated to 2.2 +/- 0.2 (P < 0.001) from a preischemic level of 1.7 +/- 0.4 and normalized by RP40, while MA hearts had a normal PCr/ATP throughout RP. Reversible RP injury transiently depresses mechanical function. Cytoplasmic CK damage during RP impairs PCr utilization, leading to a PCr overshoot. Functional recovery and metabolic recovery follow return of CK activity. Increased endogenous catalase preserves CK during RP, resulting in normal function and bioenergetics.

Adenosine Triphosphate↗

PubMed1996

The Irma dream, self-analysis, and self-supervision.

The Irma dream has special historical significance. Erikson and others have placed it in historical, social, and cultural context. The manifest dream was elaborated in terms of analytic surface with analysis of form and content, patterns and movement in time and space, etc. There are, however, limits to textual reinterpretations. Further psychobiographic consideration of the Irma dream highlights issues of transference, countertransference and their sources in unconscious conflict and trauma. The Irma dream was initially a secret dream which represented the initiation of a self-analytic and supervisory process. Freud's revealing the dream and imagining the commemoration of the discovery of "the secret of the dream" marked the termination of formal self-analysis within analysis interminable.

Countertransference↗

PubMed1995

The phosphocreatine overshoot occurs independent of myocardial work.

Although the exact mechanism(s) responsible for the phosphocreatine/ATP overshoot have not been completely elucidated, our data demonstrate that the overshoot does not stem from reduced myocardial work, and consequently, reduced utilization of phosphocreatine (PCr). Additionally, we highlight a basic difference in the physiologic responses of skeletal and cardial muscle to work demands. By understanding the bioenergetic derangements which accompany reperfusion injury, one may hope to better salvage post-ischemic myocardium.

Adenosine Triphosphate↗

PubMed1994

Intracellular sodium in cardiomyocytes using 23Na nuclear magnetic resonance.

Intracellular sodium content in superfused isolated rat cardiomyocytes was measured using 23Na nuclear magnetic resonance. The shift reagent dysprosium tripolyphosphate was added to the buffer to distinguish between NMR signals from the intracellular region and the extracellular buffer. The NMR visibility of the intracellular sodium signal was experimentally determined by measuring the changes induced in the sodium NMR signals by application of ischemia as an intervention. Intracellular volume was accounted for by determining the change in the sodium signal upon adding cells (in beads) to the buffer solution at the beginning of each experiment and by killing the cells (in beads) with Triton X-100 at the end of each experiment. The visibility of intracellular sodium (relative to extracellular) was 0.47 +/- 0.12 (mean +/- S.D., n = 12). The average intracellular sodium concentration using this visibility is 29 +/- 4.5 mM (n = 12). This value is much higher than results obtained by some investigators using NMR techniques and by others using different standard methods, with the exception of those methods which evaluate the total intracellular sodium (atomic absorption spectroscopy and X-ray microanalysis). We conclude that total Nai is higher than generally reported, using other accepted techniques such as ion-specific electrodes, and that 23Na-NMR analysis can be used to accurately determine Nai in intact cells.

Animals↗

PubMed1994

Ischemic preconditioning preserves end-ischemic ATP, enhancing functional recovery and coronary flow during reperfusion.

The mechanisms by which ischemic preconditioning (IPC) protects against reperfusion (RP) injury are unknown. The purpose of this study was to relate IPC to postischemic mechanical function, vascular reactivity, and bioenergetics. Isolated perfused rat hearts were randomized to two groups. Control (CTRL) hearts underwent 25 min of global, 37 degrees C ischemia and 40 min RP. IPC hearts underwent 2.5 min ischemia and 10 min RP followed by 25 min ischemia and 40 min RP (RP40). Left ventricular developed pressure (DP) and coronary flow were continuously measured. 31P NMR spectra determined phosphocreatine and ATP concentrations in parallel hearts every 5 min. Results are means +/- SEM; n = 6/group. Significance was assumed for P < 0.05 by paired (within groups) and unpaired (between groups) t test. CTRL heart DP recovered to 35 +/- 4% of preischemic (PI) DP by RP40 (P < 0.001), while IPC heart DP reached 99 +/- 4% (P = NS vs PI; P < 0.001 vs CTRL). CTRL coronary flow recovered to only 75 +/- 3% of PI (P < 0.001) by RP40. IPC coronary flow exceeded baseline during RP (RP40 = 118 +/- 3%, P < 0.001 vs CTRL; P < 0.05 vs PI). After 25 min ischemia, CTRL heart ATP fell to 40 +/- 4% of PI (P < 0.001) while the IPC group fell to only 60 +/- 4% (P < 0.05 IPC vs CTRL; P < 0.001 vs PI). IPC preserves more end-ischemic ATP compared to CTRL hearts with a resultant improvement in mechanical function during reperfusion. Only preconditioned hearts preserve the adaptive mechanism(s) responsible for postischemic vasodilatation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗

PubMed1994

Hepatic phosphate trapping, decreased ATP, and increased feeding after 2,5-anhydro-D-mannitol.

The mechanism by which the fructose analogue 2,5-anhydro-D-mannitol (2,5-AM) elicits feeding behavior was investigated by studying its metabolism and biochemical effects in liver. Thin-layer chromatography of liver extracts from rats given 2,5-AM containing 14C-labeled 2,5-AM showed that the analogue is phosphorylated in vivo with a time course that parallels the eating response. In vivo 31P nuclear magnetic resonance spectroscopy of rat liver during intravenous infusion of 2,5-AM and high-resolution nuclear magnetic resonance analyses of liver extracts showed that 2,5-AM is rapidly phosphorylated in liver, trapping hepatic phosphate and decreasing ATP, inorganic phosphate, and phosphate diesters. These changes occurred in a time frame in which the feeding response is elicited in conscious animals given the same dose of 2,5-AM by the same route. During an interval in which 2,5-AM increased eating, it also increased urinary uric acid excretion, implicating enhanced adenosine degradation in the reduction in hepatic ATP. These results provide the first direct evidence that changes in a high-energy phosphate-carrying compound in liver may provide a signal to initiate eating behavior.

Adenosine Triphosphate↗