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Biomedical subjects

E Freund

Publications and source records attributed to E Freund.

At least 19 recordsLinked to original sources
PubMed1990

[A new inhalation system for bronchodilatation. Study of the acceptance of the Ingelheim M inhaler in chronic obstructive respiratory tract diseases].

The aim of this study was to investigate the acceptance and convenience of a new inhalation system for the treatment of chronic obstructive pulmonary disease. The Ingelheim M inhalator, an inhalation system with a supply magazine for six powder-filled capsules represents a further development of the Ingelheim inhalator in which only a single capsule can be utilized. The study was designed as an open, randomized, crossover trial involving 60 ambulatory adult patients. Each treatment period lasted two weeks. The medication tested was Berodual Inhaletten. The success of treatment was checked on the basis of peak flow metering each morning prior to and after initial inhalation. The results of the study show a highly significant preference on the part of the patients for the new inhalation system. The advantage most emphasized by the patients was the fact that they were able to carry with them their entire daily dose. Differences in the symptomatology of chronic obstructive pulmonary disease were not observed with these inhalation systems.

Adolescent↗
PubMed1990

Expression of transforming growth factor beta 2 during the differentiation of murine embryonal carcinoma and embryonic stem cells.

Transforming growth factor beta 2 (TGF beta 2) mRNA expression was studied by Northern blot analysis in a range of feeder-independent murine embryonal carcinoma (EC) cells and in feeder-dependent EC and embryonic stem (ES) cells. TGF beta 2 transcripts were not detected in any undifferentiated cells including P19, F9, PC13, C1003, PSA-1, P10, and ES. Following induction of differentiation, however, TGF beta 2 became expressed, independently of the cell type formed. Retinoic acid (RA) addition and/or deprivation of the differentiation inhibiting activity of feeder cells resulted in the appearance of TGF beta 2 transcripts within 2 days. These kinetics correlated entirely with the first appearance of the protein; an anti-peptide antibody specifically recognizing TGF beta 2 did not stain P19 EC cells by immunofluorescence but 2-3 days after RA addition, a significant proportion of the population was strongly labeled. In addition, primitive endoderm cells emerging from the inner cell mass of substrate attached blastocysts stained brightly with anti-TGF beta 2, while the undifferentiated inner cell mass cells did not. Although all trophectoderm cells at the mid-blastocyst stage were stained, few had detectable levels of TGF beta 2 after plating on a substrate. Neither TGF beta 1 nor TGF beta 2 affected the growth of EC cells, but a range of differentiated derivatives were all inhibited, with TGF beta 2 being marginally more effective than TGF beta 1 at the same concentration.

Animals↗
PubMed1990

Expression of growth factors during the differentiation of embryonic stem cells in monolayer.

Embryonic stem (ES) cells, derived in culture directly from the inner cells mass (ICM) of blastocysts, more closely resemble their embryonic counterparts than the more commonly used embryonal carcinoma (EC) cells derived from teratocarcinomas. In view of the potential role of growth factors in early development, we have now followed changes in the expression of transforming growth factor beta (in particular TGF beta 1, beta 3, beta 4), platelet-derived growth factor (PDGF-A, PDGF-B) and insulin-like growth factor (IGF II) during the differentiation of ES cells in monolayer. When maintained in medium conditioned by Buffalo rat liver cells (BRL-CM) to inhibit differentiation, ES cells expressed 2.5 and 1.8 kb transcripts for TGF beta 1, as well as transcripts for TGF beta 4, PDGF-A, and low levels of PDGF-B, but not TGF beta 3 or IGF II. After formation of parietal endoderm-like cells by addition of retinoic acid (RA) to BRL-CM, the 1.8-kb transcript of TGF beta 1 and PDGF-A expression were reduced, IGF II mRNA and a single TGF beta 3 transcript of 3.8 kb were induced while PDGF-B and TGF beta 4 remained virtually unchanged. By contrast, in ES cells induced to differentiate by the absence of BRL-CM, unusual transcripts for TGF beta 3 of 3.0 and 6.0 kb became detectable and PDGF-B expression increased. The changes in growth factor expression in ES cells are compared with those in F9 and P19 EC cells induced to differentiate in monolayer by RA.

Animals↗
PubMed1990

Characteristics of embryonic stem cell differentiation: a comparison with two embryonal carcinoma cell lines.

Embryonic stem (ES) cells isolated from late blastocysts can now be maintained in culture in an undifferentiated state provided they are grown in the presence of a specific differentiation inhibitor, known variously as leukaemia inhibiting factor (LIF) or differentiation inhibiting activity (DIA), found at high concentrations in medium conditioned by Buffalo rat liver (BRL) cells. ES cells acquired a differentiated phenotype in monolayer, either when in the absence of LIF/DIA or in the presence of retinoic acid (RA). We have now characterized this bipotential differentiation of ES cells in terms of a series of extracellular matrix and cell surface proteins as well as cytokeratin expression, and compared it with the changes observed during the differentiation of two embryonal carcinoma (EC) cell lines, P19 and F9. ES cells exposed to RA in the presence of LIF/DIA largely resembled F9 EC + RA after 5 days, while ES cells deprived of LIF/DIA formed a culture with mixed phenotype resembling P19 EC + RA. This study therefore establishes the predominantly parietal endoderm-like phenotype of cells derived from ES by RA induction, and suggests that a mixed population of endoderm- and ill-defined mesoderm-like cells are formed after removal of specific inhibitor(s) of differentiation.

Animals↗
PubMed1990

Functional organization of the ends of IS1: specific binding site for an IS 1-encoded protein.

The IS 1-encoded protein InsA binds specifically to both ends of IS1, and acts as a repressor of IS1 gene expression and may be a direct inhibitor of the transposition process. We show here, using DNasel 'foot-printing' and gel retardation, that the InsA binding sites are located within the 24/25 bp minimal active ends of IS1 and that InsA induces DNA bending upon binding. Conformational modification of the ends of IS1 as a result of binding of the host protein integration host factor (IHF) to its site within the minimal ends has been previously observed. Using a collection of synthetic mutant ends we have mapped some of the nucleotide sequence requirements for InsA binding and for transposition activity. We show that sequences necessary for InsA binding are also essential for transposition activity. We demonstrate that InsA and IHF binding sites overlap since some sequence determinants are shared by both InsA and IHF. The data suggest that these ends contain two functional domains: one for binding of InsA and IHF, and the other for transposition activity. A third region, when present, may enhance transposition activity with an intact right end. This 'architecture' of the ends of IS1 is remarkably similar to that of IS elements IS10, IS50 and IS903.

Bacterial Proteins↗
PubMed1988

[Experimental studies in animals of the regeneration of peripheral nerves].

In bridging nerve gaps and studying the process of nerve regeneration the method of "tubulation" becomes of new worldwide importance during the last years. In this technique the both stumps are introduced in a preformed tube without tension, the further healing process is left to the neuron's potency for self-repair. Although until now the experimental results confirm the possibility of this management it is often impossible to compare the findings because of the insufficient quantitative analyses. In this paper the own results of bridging a 4-6 mm defect in rat sciatic nerves with a connective tissue-teflon-tube are presented including an extensive quantitative analysis with methods of computer-based multivariate data analysis. The theoretic advantages of this technique are discussed in relation to the autologous interfascicular nerve transplantation.

Animals↗
PubMed1986

Identification of a nucleoside triphosphate binding site on calf thymus RNA polymerase II.

A nucleoside triphosphate binding site on calf thymus RNA polymerase II was identified by using photoaffinity analogues of adenosine 5'-triphosphate and guanosine 5'-triphosphate. Both radiolabeled 8-azidoadenosine 5'-triphosphate (8-N3ATP) and radiolabeled 8-azidoguanosine 5'-triphosphate (8-N3GTP) bound to a single polypeptide of this enzyme. This polypeptide has a molecular mass of 37 kilodaltons and an isoelectric point of 5.4. Ultraviolet (UV) irradiation was necessary for photolabeling to occur. In addition, no labeling occurred when the probe was prephotolyzed or when the enzyme was inactivated. Furthermore, photolabeling of the enzyme could be decreased by preincubation with natural substrates. To provide evidence that the radiolabeled polypeptide forms a part of the domain of the nucleoside triphosphate binding site, experiments were performed using unlabeled 8-N3ATP. Although this unlabeled analogue was not a substrate for RNA polymerase II, it photoinactivated the enzyme in the presence of UV irradiation, and it inhibited transcription elongation by the enzyme in a competitive manner in the absence of UV irradiation. As in the case with photolabeling, photoinactivation by 8-N3ATP could be decreased by natural substrates; in both cases, purine ribonucleoside triphosphates were more efficient than pyrimidine nucleoside triphosphates. Furthermore, photoinactivation was saturable at about the same concentration as the inhibition constant for 8-N3ATP. Collectively, these results provide evidence that the radiolabeled polypeptide in calf thymus RNA polymerase II is an essential component for activity and suggest that this polypeptide may be part of this enzyme's purine ribonucleoside triphosphate binding site.

Adenosine Triphosphate↗
PubMed1986

Characterization of RNA polymerase type II from human term placenta.

RNA polymerase type II from human term placenta has been isolated and characterized with respect to its template, ammonium sulfate, divalent cation, and buffer preferences. In addition, the apparent Michaelis constants for AMP and UMP incorporation have been determined. The enzyme was also analyzed by native and denaturing polyacrylamide gel electrophoresis, and evidence is presented that a single polypeptide is radiolabeled with azido purine nucleoside triphosphate photoprobes.

Adenosine Triphosphate↗
PubMed1986

[Toe transfer to a mid-hand stump covered with abdominal skin].

Following amputation of all four fingers from the hand, the cover of the amputation site with an abdominal flap gives a hand which is functionally inferior. This paper reports our experiences of three toe transfers to such a hand in two patients, one a 22-year-old man, the other, a 50-year-old woman. In our opinion, the toe transfer will be successful if the vessels, nerves and tendons are harvested to the level of the extensor retinaculum, giving a length in excess of the skeleton of some 12-15 cm. The routing of these structures beneath the abdominal flap is done in such a way as to avoid any ischemia and therefore, infection. In the first case, these latter considerations were not fully observed and in the third postoperative week, arterial thrombosis with loss of the transfer developed, following an infection. The two other transposed digits have survived with a good functional result.

Adult↗
PubMed1985

[Toe transfer].

Today toe-to-hand transfer by micro-anastomoses is one of the most important methods in reconstructing severely injured hands. An experienced surgeon will obtain a survival rate of the transplant in about 94 to 96% of cases. All measures required can be performed by only one operation. The free toe-to-hand transfer guarantees the best functional and aesthetic results so far known.

Amputation, Traumatic↗
PubMed1985

[Cephalic insulin secretion--neuromorphologic findings].

The paper presented deals with the electron microscopy bases of experimental results, which show a cephalic insulin secretion. The B cell-producing insulin--is a highly innervated endocrine cell. Several nerve endings often form synaptic connexions at a single B cell. The synaptic clefts are usually 20-25 nm. The nerve endings cause an evident impression of the cell membrane. The narrow neuro-cellular connexions form a structural bases of the cephalic insulin response. The interruption of this reflex loop caused by vagotomy eliminates cephalic mechanism. However, the innervation of the islets (electron microscopic examination) remains unaffected. Therefore the intramural nervous mechanism seems to be not excluded by vagotomy.

Animals↗