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Biomedical subjects

H Meisner

Publications and source records attributed to H Meisner.

At least 37 records · Page 2Linked to original sources
PubMed1991

Experience with anatomical correction of transposition of the great arteries (TGA).

During the past seven years, 102 patients with TGA have been operated on using the switch operation. Overall early mortality was 5.9%, late mortality 2.%. Sixty-three newborns had an intact septum and were corrected between the 3th and 35th day after birth, 39 had a ventricular septal defect and/or associated anomalies. All operations were carried out under ECC and deep hypothermia. Myocardial function was recorded intraoperatively by using sonomicrometry. The data demonstrate that adaptation of the left ventricle to the new load conditions should be supported by drugs providing inotropic stimulation and afterload reduction. Mean follow-up time is 32.5 months, no rhythm problems have been recorded during that period, a few children revealed trivial pulmonary or aortic valve stenosis and/or incompetence. The switch operation permits good early results for newborns with TGA and intact septum and TGA with VSD. A decade has to pass in order to judge the long-term results.

Follow-Up Studies↗
PubMed1991

Long-term results after right ventricular outflow tract reconstruction with porcine and allograft conduits.

From 1975 to 1989, a total of 353 patients were operated for complex cardiac malformations with impaired pulmonary artery perfusion using 53 non-valved and 300 valved right heart to pulmonary artery conduits. In 108 patients a porcine conduit (Hancock or Carpentier-Edwards) 12-30 mm was used; the age range was 14 days to 37 years (mean 4.3 years) and body weight 2.9-68 kg (mean 15.3 kg). One hundred and ninety-two patients had an allograft of 9-29 mm implanted at the age of 17 days to 26 years (mean 3.8 years), body weight 2.7-73 kg (mean 14.2 kg). So far, 32 of the porcine valved conduits have had to be exchanged 2.5-10.5 years (mean 6.1 +/- 2.1 years) after the first implantation. In 3 patients, reoperated before 1982, another porcine valved conduit was used. After 1982, 29 exchanges were all performed using allografts. The main reason for xenograft conduit malfunction was degeneration and/or calcification of the valves. Some conduits, however, with rather small sizes of 12 and 14 mm had to be exchanged in spite of still sufficient function because the children had "outgrown" the conduit and needed a bigger one. Out of 192 patients with allografts implanted since 1982, so far 5 patients have had to be reoperated 2 months to 6 years (mean 4.6 +/- 2.8 years) after the first operation. The causes of allograft failure were degeneration and, in one case, infection of the conduit. Even though allografts seem to be the conduit of choice for right ventricular outflow tract reconstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Long-term results after right ventricular outflow tract reconstruction with porcine bioprosthetic conduits.

From 1975 to 1990, a total of 110 patients were operated for complex cardiac malformations with impaired pulmonary artery perfusion using porcine valved right heart to pulmonary artery conduits. Twelve- to 30-mm porcine valved conduits (Hancock or Carpentier-Edwards) were implanted at the age of 4 weeks to 28 years (mean 4.3 years). The patients' body weights were 2.9-68 kg (mean 15.3 kg). Early mortality was 5.5% (six patients), late mortality was 12.7% (14 patients), and 90 patients could be included in this long-term follow-up (426 patient-years). So far, 41 of the conduits had to be exchanged 4 months to 15 years (mean 6.5 years) after the first implantation. Forty-nine of the conduits are still in place. At reoperation, 38 patients received an allograft; three patients, reoperated before 1982, had a second xenograft. The main reason for porcine conduit malfunction was degeneration and/or calcification of the valves. In 11 patients, however, with 12- and 14-mm conduits implanted at a mean age of 3.1 years, a reoperation was necessary after a mean time of 6.8 years because these children had "outgrown" the conduit and needed a bigger one. We conclude that even though allografts seem to be the conduit of choice for right ventricular outflow tract reconstruction, our clinical experience shows that porcine valved conduits can be used just as well since most of them function sufficiently well for as long as 5 to 10 years, and early valve failure is relatively rare.

Adolescent↗
PubMed1990

Special considerations on primary cardiac tumors in infancy and childhood.

Primary cardiac tumors are rare at all ages and are even less common in infants and children. In the vast majority of cases, they are benign tumors that show little tendency to growth. Primary malignant tumors of the heart are exceptionally rare. Rhabdomyomas are the most common type of tumors in infants, followed in frequency by the fibromas and the teratomas. Myxomas are very rare in pediatric patients. Symptoms that derive from the presence of a neoplastic mass are usually due to obstruction or compression. In young symptomatic patients, usually affected by rhabdomyomas, there is little chance of survival without surgery. On the other hand several patients with cardiac neoplasms are totally asymptomatic. The indication for surgery is differenciated according to the severity of the clinical picture. Since 1974, 15 infants with a cardiac tumor have been observed in our hospital. Our recent experience with 5 cases, which are described in this report, confirm our opinion, that the most important fact is the restoration of the best possible heart function. Total resection of a tumor should not always be the main therapeutical aim. Surgical intervention is required for those patients, who develop relevant clinical symptoms. Close observation of the clinical course is mandatory in all patients with a doubtful indication for operation.

Child, Preschool↗
PubMed1990

[Clinical experiences and long-term results after surgical treatment of type A thoracic aortic aneurysm].

For aortic aneurysms type A operative treatment is the method of choice. During the past 15 years 128 patients with this diagnosis have been operated on. Early mortality was 22%, 77% of all dissections were emergencies. Main causes of death were multiorgan failure. Up to 117 months 8 patients died late in part due to additional ruptures. 17% of the survivors required reoperation up to 154 months. The probability of survival after 10 years is 0.78, in the group with dissections only 0.4. Therefore close follow-up of this patient group is necessary in order to recognize progression of the disease and induce elective operative treatment.

Adult↗
PubMed1990

[Intraoperative diagnosis of the heart and great vessels--measuring blood flow and angiocardiography].

Among the methods for intraoperative diagnosis during cardiac surgery, flow measurements and angiography are of significant value. According to our experience, the electromagnetic method is the leading technique for judging bypass flow after coronary artery surgery; new trends using ultrasound techniques are promising. An exact demonstration and documentation of the operative situation, (e.g., bypass surgery) is only possible using intraoperative cinecoronary angiography. A wall-mounted unit provides excellent pictures; the method, however, is elaborate, expensive, and confined to one operating table only. Thus, a transportable angiography unit is desired that uses digital spot imaging for better evaluation. Recent developments such as intraoperative angioscopy, thermoangiography, and two-dimensional echocardiography present a promising outlook.

Angiocardiography↗
PubMed1989

Cloning and characterization of a cDNA encoding the beta subunit of human casein kinase II.

Previous studies [Summercorn et al. (1987) Proc. Natl. Acad. Sci. U.S.A. 84, 8834-8838; Klarlung & Czech (1988) J. Biol. Chem. 263, 15872-15875] have indicated that Balb/c 3T3 cells and 3T3-L1 adipocytes incubated with insulin show increased casein kinase II activity within minutes, implicating this serine/threonine kinase as an early step in an insulin signaling pathway. We recently reported the isolation of a cDNA encoding an alpha subunit of human casein kinase II [Meisner et al. (1989) Biochemistry 28, 4072-4076] as an initial step toward examining the regulation of this enzyme. We now describe a HepG2 cell casein kinase II beta subunit cDNA of 2.57 kb containing 96 bases of 5' untranslated sequence, 645 bases of open reading frame, and 1832 bases of 3' untranslated sequence with two polyadenylation consensus signal sequences and two poly(A) stretches. The open reading frame of the human beta subunit cDNA was 77% and 87% identical with the Drosophila sequence at the nucleotide and amino acid levels, respectively, and 99% identical with the bovine amino acid sequence. RNA analysis of HepG2 cell RNA utilizing HepG2 beta subunit cDNA fragments as probes revealed one major band migrating at 1.2 kb and two minor bands migrating at 3.0 and 4.2 kb. Results from DNA analysis of HepG2 genomic DNA, consistent with results utilizing Drosophila genomic DNA, suggest the presence of a single gene for the beta subunit of casein kinase II.

Amino Acid Sequence↗
PubMed1989

Molecular cloning of the human casein kinase II alpha subunit.

A human cDNA encoding the alpha subunit of casein kinase II and a partial cDNA encoding the rat homologue were isolated by using a Drosophila casein kinase II cDNA probe. The 2.2-kb human cDNA contains a 1.2-kb open reading frame, 150 nucleotides of 5' leader, and 850 nucleotides of 3' noncoding region. Except for the first 7 deduced amino acids that are missing in the rat cDNA, the 328 amino acids beginning with the amino terminus are identical between human and rat. The Drosophila enzyme sequence is 90% identical with the human casein kinase II sequence, and there is only a single amino acid difference between the published partial bovine sequence and the human sequence. In addition, the C-terminus of the human cDNA has an extra 53 amino acids not present in Drosophila. Northern analysis of rat and human RNA showed predominant bands of 5.5, 3.1, and 1.8 kb. In rat tissues, brain and spleen had the highest levels of casein kinase II alpha subunit specific RNA, while skeletal muscle showed the lowest. Southern analysis of human cultured cell and tissue genomic DNA using the full-length cDNA probe revealed two bands with restriction enzymes that have no recognition sites within the cDNA and three to six bands with enzymes having single internal sites. These results are consistent with the possibility that two genes encode the alpha subunits.

Amino Acid Sequence↗
PubMed1988

Renal enzyme activities in experimental ochratoxin A-induced porcine nephropathy: diagnostic potential of phosphoenolpyruvate carboxykinase and gamma-glutamyl transpeptidase activity.

Enzyme activities have been measured in needle biopsies from kidneys of pigs fed 1 ppm or 0.2 ppm of ochratoxin A for 1-5 wks. After feeding 1 ppm toxin for 1 wk, the activity of cytosolic phosphoenolpyruvate carboxykinase (PEPCK) was decreased by 40% and remained inhibited until the termination of the experiment (5 wk). The activity of gamma-glutamyl transpeptidase, a brush-border enzyme found in the proximal tubules, was reduced to a similar degree and remained inhibited. The activities of hexokinase, a cytosolic enzyme of general distribution in the nephron, and phosphate-dependent glutaminase, a distal tubule enzyme, were not affected. The biopsy results were confirmed by measurements in renal slices taken at the termination of the experiment, except that biopsy samples showed more variation in enzyme activity and a lower PEPCK activity. A guinea pig antibody against the cytosolic form of PEPCK was used to demonstrate that the mitochondrial form of the enzyme, which accounts for a considerable part of the total cellular activity, was not affected by ochratoxin A. When mitochondrial PEPCK activity present in the cytosolic fraction was accounted for, ochratoxin A was found to reduce PEPCK activity by 70-80%. The increase of ochratoxin A exposure from zero through 0.2 ppm to 1 ppm, which resulted in dose-dependent activity decrease of PEPCK and gamma-glutamyl transpeptidase, was accompanied by dose-dependent decrease of renal function, as measured by a reduction of maximal tubular excretion of para-aminohippurate per clearance of inulin (TmPAH/CIn) and an increase in glucose excretion. This suggest that these enzymes are sensitive indicators of ochratoxin A-induced porcine nephropathy. Assuming that porcine nephropathy represents a valid model of endemic (Balkan) nephropathy in humans, the measurement of cytosolic PEPCK and gamma-glutamyl transpeptidase activity in the kidney could be a sensitive test for ochratoxin A-induced disease in humans.

Animals↗
PubMed1987

Regulation of transferrin receptor cycling by protein kinase C is independent of receptor phosphorylation at serine 24 in Swiss 3T3 fibroblasts.

Treatment of Swiss 3T3 fibroblasts with tumor-promoting phorbol diester or with platelet-derived growth factor caused the phosphorylation of the transferrin receptor by protein kinase C (Ca2+/phospholipid-dependent enzyme) at serine 24 and increased the cell surface expression of the transferrin receptor. The hypothesis that the regulation of transferrin receptor cycling by protein kinase C is causally related to the phosphorylation of the receptor at serine 24 was critically tested. Site-directed mutagenesis of the human transferrin receptor cDNA was used to substitute serine 24 with threonine or alanine residues in order to create phosphorylation defective receptors. Wild-type and mutated transferrin receptors were expressed in Swiss 3T3 fibroblasts using the retrovirus vector pZipNeoSV (X). These receptors were functionally active and caused the receptor-mediated endocytosis of diferric transferrin. Incubation of the fibroblasts with phorbol diester caused the phosphorylation of the wild-type (Ser-24) human transferrin receptor, but this treatment did not result in the phosphorylation of the mutated (Ala-24 and Thr-24) receptors. The cycling of the phosphorylation defective receptors was regulated by phorbol diester and platelet-derived growth factor in a manner similar to that observed for the wild-type receptor. We conclude that the regulation of transferrin receptor cycling by protein kinase C is independent of receptor phosphorylation at serine 24 in Swiss 3T3 fibroblasts.

Animals↗
PubMed1986

Androgen induction of messenger RNA concentrations in mouse kidney is posttranscriptional.

The concentrations of several mRNAs in mouse kidney increase in response to testosterone. To determine if the increases are generated at the level of gene transcription, we have assayed transcription rates for several androgen-inducible mRNAs in kidney nuclei in vitro. No significant changes were found in the synthesis of three mRNAs whose concentrations increase 10-20-fold during testosterone treatment. Kinetic analysis of changes in transcript levels after testosterone administration and withdrawal suggests that mRNA stabilization is a major factor in the inductions. Thus, the androgen-mediated induction of these kidney mRNAs is generated predominantly at the posttranscriptional level.

Animals↗
PubMed1986

Changes of renal mRNA species abundance by ochratoxin A.

Ochratoxin A is a nephrotoxin produced by certain species of Aspergillus and Penicillium. We have found previously that renal but not hepatic P-enolpyruvate carboxykinase, and the mRNA for this enzyme, are rapidly decreased in rats and swine fed 0.1 to 1 mg/kg body weight for a few days. In the present study, we isolated kidney mRNA from rats fed ochratoxin A for 2-5 days. By screening a rat kidney cDNA library with [32P]RNA, we have identified several renal mRNAs whose concentration is changed within 2 days by the toxin. The transcription rate of each mRNA was measured in nuclei isolated from kidneys of rats fed ochratoxin A. The incorporation of [32P]UMP into P-enolpyruvate carboxykinase mRNA and the synthesis of other RNAs were not affected. Therefore, the toxin changes mRNA abundance at the post-transcriptional level.

Animals↗
PubMed1986

Interrupted aortic arch: natural history and operative results.

The chances of survival for patients with interruption of the aortic arch depend mainly on early recognition and medical treatment before symptoms of cardiogenic shock appear, and specifically on early operative repair after the exact diagnosis has been established. Accurate angiography with visualization of the interrupted aortic arch and delineation of associated cardiac malformations is of prime importance for the surgical management and prognosis. Among our 36 patients with interrupted aortic arch, 27 were operated on. The operative mortality in 22 patients with associated ventricular septal defect (VSD) and persistent ductus arteriosus (PDA) was reduced from 43% (in seven patients seen up until 1979) to 7% (in 15 patients seen since 1980). One patient with interrupted aortic arch type C and another infant with associated truncus arteriosus were successfully corrected on day 9 and day 17 of life, respectively. In the patients with associated VSD and PDA as well as in the one patient with associated truncus arteriosus, the primary correction--direct anastomosis of the interrupted segments without prosthesis and VSD closure and in the case with truncus, the additional positioning of a valve-bearing allograft conduit from the right ventricle to the pulmonary artery--has been more successful than a two-step approach with initial pulmonary artery banding.

Aorta, Thoracic↗
PubMed1985

[Reconstruction of the right ventricular outflow tract with xenogeneic or allogeneic valve-bearing conduits].

From April 1974 to February 1985 131 patients were operated for reconstruction of the right ventricular outflow tract with 147 valve-carrying conduits. 79 were xenogenic (XC) and 68 sterilized and preserved allogenic (AC) conduits between right heart and lung in the following heart defects: DOLV 2, DORV 6, Fallot 24, pulmonary atresia 33, TGA, VSD and pulmonic stenosis 20, single ventricle 7, tricuspid atresia 10 and truncus arteriosus 41. Mean age was 6.6 and 5.2 years of age. The operative mortality was 13.6%. 11 more patients died later--2.0 months to 2.5 years postoperatively. 16 patients were reoperated (change of the conduit). The observation time is now 5 years in the XC-group and 1.4 years in the AC series. Up to now no dysfunction in the AC-group could be seen.

Adolescent↗
PubMed1985

Effect of hormones on transcription of the gene for cytosolic phosphoenolpyruvate carboxykinase (GTP) in rat kidney.

The effect of hormones on the transcription rate of cytosolic phosphoenolpyruvate carboxykinase and level of mRNA for this enzyme in the rat kidney has been investigated. In renal nuclei isolated from rats given dibutyryladenosine cyclic 3',5'-phosphate (Bt2cAMP) or 8-bromoadenosine cyclic 3',5'-phosphate (8-Br-cAMP), [32P]UMP incorporation into hybridizable phosphoenolpyruvate carboxykinase mRNA increased severalfold within 1 h. Changes in the concentration of cytosolic phosphoenolpyruvate carboxykinase mRNA, measured by hybridization of [32P]cDNA to poly(A)+ mRNA, paralleled alterations in the transcription rate. Dexamethasone treatment of adrenalectomized rats increased the transcription rate and the level of phosphoenolpyruvate carboxykinase mRNA 3-4-fold after 4 h. Both parameters then declined to control values by 8 h. When dexamethasone (5 mg/kg) and Bt2cAMP (25 mg/kg) were given together, the rate of phosphoenolpyruvate carboxykinase RNA synthesis and the level of cytosolic mRNA were not increased more than those with either drug alone. Transcription of the gene for renal phosphoenolpyruvate carboxykinase was not affected by diabetes or glucose refeeding but was increased 2-fold after 24 h of starvation and reduced by bicarbonate feeding after 2 h. We conclude that glucocorticoids and cAMP change the rate of transcription of the phosphoenolpyruvate carboxykinase gene in rat kidney, leading to changes of similar magnitude in mRNA level and, hence, enzyme activity. The results presented here and in previous work [Lamers, W., Hanson, R. W., & Meisner, H. (1982) Proc. Natl. Acad. Sci. U.S.A. 79, 5137] indicate that the transcription rate of the gene for phosphoenolpyruvate carboxykinase in liver and kidney responds to hormones in a tissue-specific manner.

Animals↗
PubMed1985

Ten years experience with povidone-iodine in heart surgery.

Ten years experience with povidone-iodine (PVP-I) (10%) ('Beta-isodona') in 7566 patients undergoing open-heart operations in the German Heart Centre, Munich, is reported. Povidone-iodine was used pre-, intra- and postoperatively for skin and wound disinfection according to a regime introduced more than 10 years ago and retained unchanged until today. The incidence of minor, superficial wound healing defects was 5%, whereas severe, deep sternal or retrosternal infections occurred in 0.5% of all patients. Superficial infections are no risk to the patient and can be treated successfully with local application of PVP-I. Deep infections, however, are associated with a mortality of about 40% despite the use of antibiotics and continuous wound irrigation with PVP-I (0.5%). Many factors contribute to the risk of these infections and only meticulous observation of aseptic and surgical technique, the prophylactic and therapeutic use of highly effective antibiotics, as well as the exclusion of sources of exogenous bacteria, can further reduce the incidence of these complications.

Anti-Bacterial Agents↗