PubMed Health⌕ Search

Biomedical subjects

U Müller

Publications and source records attributed to U Müller.

At least 415 records · Page 23Linked to original sources
PubMed1989

Glomerular tubular balance: mediation by luminal hypotonicity.

Late proximal rat tubular segments were microperfused with slightly hypo- or hypertonic artificial late proximal tubular fluid (ATF) at low (11-13 nl/min) or high (30-38 nl/min) perfusion rates. Volume reabsorption, net chloride and solute reabsorption were measured as a function of length. In addition, the transepithelial resistance and voltage (Vte) were measured as a function of the applied osmotic gradient. Hypertonic solutions equilibrated to isotonicity by solute outflow rather than water influx. With hypertonic ATF the lumen positive Vte was decreased compared with free flow or with hypotonic ATF. The resistance was not significantly different between the different groups. In contrast to hypotonic ATF, hypertonic or isotonic ATF was not significantly reabsorbed. In addition, hypotonic ATF maintained its hypotonicity along the perfused segments. Its reabsorption was flow-dependent. Hypotonicity appeared to enhance solute reabsorption.

Absorption↗
PubMed1988

Structure of a hypervariable tandemly repeated DNA sequence on the short arm of the human Y chromosome.

The structure of a repeated DNA sequence located on the short arm of the human Y chromosome is described. Genomic mapping and cloning in lambda or cosmid vectors show that the repeated sequence consists of units 20.3 x 10(3) base-pairs long that contain the three previously described DNA sequences: Y-156, Y-190 and Y-223a. Analysis of male genomic DNA by pulsed-field gel electrophoresis shows that the units are tandemly arranged and are organized into two blocks. The major block is hypervariable in size and alleles in the range approximately 540 x 10(3) to 800 x 10(3) base-pairs were detected. The minor block is not variable in size and is approximately 60 x 10(3) base-pairs long. Analysis of rearranged Y chromosomes shows that both blocks are located on the short arm of the chromosome. Most commonly, the major block is distal to the minor block, but the opposite arrangement is also found.

Cell Line↗
PubMed1988

Reactivation of the methylation-inactivated late E2A promoter of adenovirus type 2 by E1A (13 S) functions.

The inactivating effect of sequence-specific promoter methylations was extensively studied by using the late E2A promoter of adenovirus type 2 (Ad2) DNA. The modification of the three 5' CCGG 3' sequences at nucleotides +24, +6 and -215, relative to the cap site in this promoter, sufficed to silence the gene in transient expression either in Xenopus laevis oocytes or in mammalian cells, and after the fixation of the E2A promoter-chloramphenicol-acetyltransferase (CAT) gene construct in the genome of hamster cells. It will now be demonstrated that the inactivation of the late promoter of Ad2 DNA can be reversed by transactivating functions that are encoded in the 13S messenger RNA of the E1A region of Ad2 DNA. The reactivation of a methylation-inactivated eukaryotic promoter by transactivating functions has general significance in that the value of a regulatory signal can be fully realized only by its controlled reversibility. It was demonstrated in transient expression experiments that the 5' CCGG 3'-methylated late E2A promoter was at least partly reactivated in cell lines constitutively expressing the E1 region of Ad2 or of adenovirus type 5 (Ad5) DNA. The reactivation led to transcriptional initiation at the authentic cap sites of the late E2A promoter and was not associated with promoter demethylation, at least not in both DNA complements. Reactivation of the methylation-inactivated E2A promoter could also be demonstrated in two BHK21 cell lines (mc14 and mc20), which carried the late E2A promoter-CAT gene assembly in an integrated form. In these cell lines the late E2A promoter was methylated and the CAT gene was not expressed. By transfection of cell lines mc14 and mc20, the reactivating functions were shown to reside in the pAd2E1A-13 S cDNA clone of Ad2 DNA. The pAd2E1A-12 S cDNA clone or the pAd2E1B clone showed no reactivating function. These findings implicated the E1A 289 amino acid residue protein of Ad2, a well-known transactivator, as the reactivating function of the endogenous, previously dormant, late E2A promoter-CAT gene assembly. The methylated promoter was not demethylated, at least not in both complements, and it was shown that reactivation of the methylated promoter entailed transcriptional initiation at the authentic late E2A cap site. Since E1A and E1B jointly had a more pronounced effect, it was conceivable that genes in both regions acted together in the abrogation of the inhibitory effect of promoter methylations in the late E2A promoter.

Adenoviridae↗
PubMed1988

Immunoprecipitation of a male-specific polypeptide after in vitro translation of testicular poly(A)+ RNA.

Poly(A)+ RNAs from male and female gonads of 20-day-old rats were translated in vitro using rabbit reticulocyte lysates. The resulting polypeptides were incubated with specific anti-male (anti-H-Y) antisera raised in female rats by intrasplenic immunization with syngeneic male skin. Using a second antibody, a male-specific polypeptide of molecular weight approximately 18,000 was immunoprecipitated. This male-specific polypeptide was not cotranslationally modified in vitro and appeared to be identical to serological H-Y antigen.

Animals↗
PubMed1988

1-O-methyl-rac-glycerol: a new agent for the cryopreservation of mononuclear cells.

1-O-methyl-rac-glycerol (1-O-MG), also known as 3-methoxy-1,2-propanediol is a lipophilic derivative of glycerol, and has been studied as a new cryoprotective agent (CPA) for mononuclear blood cells (MNC), a well-established experimental model in cryopreservation. The chemical modification of the glycerol molecule results in improved cryobiological properties, such as membrane permeability, thus allowing easier handling in the freeze/thaw process. The optimum preincubation period for MNC and 1-O-MG before freezing is 5 min at 4 degree C, resulting in 86% recovery of viable cells, whereas optimal recovery of glycerol-frozen MNC is only guaranteed after 30 min of preincubation at room temperature (74% viable recovery). The optimal concentration of 1-O-MG is 10% (v/v). Although this new agent offers no improvement in cryoprotective properties over dimethyl sulfoxide (Me2SO) there may be possible pharmacological advantages when used in humans. It is, however, obviously superior to glycerol with regard to its permeation kinetics. 1-O-MG might therefore also be of interest in the cryoprotection of other hematopoietic cells and biological tissues.

Blood Preservation↗
PubMed1988

Twelve loci form a continuous linkage map for human chromosome 18.

We have constructed a primary genetic map of human chromosome 18 consisting of 11 DNA markers and one serological marker (JK). Two of these loci define highly polymorphic VNTR systems. The markers define a continuous genetic linkage map of 97 cM in males and 205 cM in females; female genetic distances in a panel of 59 three-generation families were consistently about twice those observed in males. The high odds in support of the linear order of the markers on this recombination map, and the extent of coverage of chromosome 18, indicate that this map will permit efficient linkage studies of human genetic diseases that may be segregating on chromosome 18 and will provide anchor points for development of high-resolution maps for this chromosome.

Alleles↗
PubMed1988

Changes in the pattern of microsomal fatty acids in rat liver after thermal injury and therapeutic intervention.

Despite substantial progress in handling the acute phase after thermal injury, severely burned patients still succumb to systemic sepsis as a consequence of a compromised defence system. It is likely that autotoxic mechanisms play an important role in the aetiology of the impaired host defence. One of the primary target systems of autotoxic cell damage is the liver. In the present work oxidative alterations in the microsomal compartment of liver cells have been investigated. It was found that thermal burns are associated with extensive oxidation of polyunsaturated fatty acids which can be antagonized by antioxidants such as silibinin.

Animals↗
PubMed1988

Insulin-like growth factor I in depressed patients and controls.

To explore the role of the somatomedin-mediated long-loop negative feed-back mechanism in altered growth hormone (GH) secretory dynamics associated with depression, plasma IGF-I concentrations were measured in 34 patients with a major depressive episode and matched healthy subjects. Compared with controls, depressed patients exhibited significantly increased plasma IGF-I concentrations. In the patient group plasma IGF-I concentrations were positively correlated with the maximum post-dexamethasone plasma cortisol concentrations. Our data suggest that increased plasma IGF-I concentration may reflect diurnal GH hypersecretion, contribute to deficient GH responses to dynamic challenges, and indicate an interrelationship between the hypothalamic-pituitary-somatotropic (HPS) and -adrenocortical (HPA) system regulation in depression.

Adult↗
PubMed1988

Degradation of 1,4-naphthoquinones by Pseudomonas putida.

Pseudomonas putida J1 and J2, enriched from soil with juglone, are capable of a total degradation of 1,4-naphthoquinone, 2-hydroxy-1,4-naphthoquinone, and 2-chloro-1,4-naphthoquinone. Naphthazerin and plumbagin are only converted into the hydroxyderivatives 2-hydroxynaphthazerin and 3-hydroxyplumbagin, respectively, whereas 2-amino-1,4-naphthoquinone is not attacked at all. The degradation of 1,4-naphthoquinone begins with a hydroxylation of the quinoid ring, yielding 2-hydroxy-1,4-naphthoquinone (lawsone). Lawsone is reduced to 1,2,4-trihydroxynaphthalene with consumption of NADH. The fission product of the quinol could not be detected by direct means because of its instability. However, the presence of 2-chromonecarboxylic acid, a secondary product of lawsone degradation, leads to the conclusion, that the cleavage of the quinol takes place in the meta-position. The resulting ring fission product is converted into salicylic acid by removal of the side chain, presumably as pyruvate. Further degradation of salicyclic acid leads to the formation of catechol, which is then cleaved in the ortho-position and then metabolized via the 3-oxoadipate pathway. The initial steps in the degradation of 2-chloro-1,4-naphthoquinone, namely, the hydroxylation of the quinone to 2-chloro-3-hydroxy-1,4-naphthoquinone, followed by the elimination of the chlorine substituent lead to lawsone, which is further degraded through the pathway described. The degradation steps could be verified by the accumulation products of mutant strains blocked in different steps of lawsone metabolism. Generation of mutants was carried out by chemical and by transposon mutagenesis. The regulation of the first steps of the pathway catalysed by juglone hydroxylase and lawsone reductase, was investigated by induction experiments.

Biotransformation↗
PubMed1988

H-Y antigens, testis differentiation, and spermatogenesis.

H-Y antigen defined by graft rejection and by cytotoxic T cell action ('transplantation H-Y') appears to be different from H-Y antigen that is characterized by antibodies ('serological H-Y'). Gene(s) for the transplantation H-Y were assigned to the long arm or to the centromeric region of the human Y chromosome. A regulatory gene for serological H-Y seems to be located in a distal region of the Y short arm. Various investigations suggest that serological H-Y has a molecular weight of approximately 18,000. While serological H-Y might be involved in the differentiation of the heterogametic gonad of vertebrates, transplantation H-Y may be required for normal spermatogenesis to occur in mammals.

Animals↗
PubMed1988

[Treatment of severe respiratory distress syndrome in the premature infant with natural surfactant].

14 preterm infants with severe respiratory distress syndrome (birthweight 1170 +/- 369 g, mean +/- 1SD) have been treated with a single dose of natural porcine surfactant (Curosurf, 200 mg/kg); follow up and outcome data were compared with matched controls (1200 +/- 288 g, n = 20). Treated infants showed improved oxygenation and gas exchange within minutes after surfactant application. Duration of intermittent positive pressure ventilation was significantly reduced in treated patients when compared to controls (surfactant treated: 16 d (mean value), controls 27 d, p less than 0.05). Similarly, total exposition in greater than 40% oxygen was 5.5 h in treated infants versus 79 h in controls (p less than 0.001). Pneumothorax occurred in 7 of the 20 control infants (35%), but in none of the treated patients (p less than 0.05). However, haemodynamically significant patent ductus arteriosus (PDA) occurred more often in the surfactant group (50% versus 30%, not significant). The incidence of PDA requiring treatment was the same in both groups. Occurrence of intracranial haemorrhage, bronchopulmonary dysplasia and retinopathy of prematurity was identical in both groups. Mortality was 25% in controls and 7% in treated babies. This study confirms the efficacy of surfactant treatment in neonates with severe respiratory distress syndrome.

Birth Weight↗
PubMed1988

[Is spontaneous, internal bilio-digestive fistula a surgical indication?].

Spontaneous enterobiliary fistulas are recognized preoperatively in only about 50 per cent of patients. Ultrasonography and intravenous cholangiogram merely demonstrate alterations of cholelithiasis. In plain abdominal radiograph biliary gas is presumptive evidence of enterobiliary fistula formation. Barium studies or ERC often succeed in outlining fistula preoperatively. Because of additional findings in more than 70 per cent of cases, such as calculous biliary disease, carcinoma of gallbladder and ascending cholangitis surgical repair of enterobiliary fistula always should be performed. This counts among the most difficult surgical procedures in biliary tract and is burdened with a mortality of 4 to 22 per cent. Experience with 33 patients operated on are reported. In 5 patients enterobiliary fistula was associated with carcinoma of gallbladder, which was discovered in 3 patients only at histopathologic investigation.

Adult↗