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Biomedical subjects

A Seiler

Publications and source records attributed to A Seiler.

At least 19 recordsLinked to original sources
PubMed2001

Transmission of the Ambystoma tigrinum virus to alternative hosts.

Ambystoma tigrinum virus (ATV) is a lethal virus originally isolated from Sonora tiger salamanders Ambystoma tigrinum stebbinsi in the San Rafael Valley in southern Arizona. USA. ATV is implicated in several salamander epizootics. We attempted to transmit ATV experimentally to fish and amphibians by injection, water bath exposure, or feeding to test whether ATV can cause clinical signs of infection or be recovered from exposed individuals that do not show clinical signs. Cell culture and polymerase chain reaction of the viral major capsid protein gene were used for viral detection. Salamanders and newts became infected with ATV and the virus was recovered from these animals, but virus could not be recovered from any of the frogs or fish tested. These results suggest that ATV may only infect urodeles and that fish and frogs may not be susceptible to ATV infection.

Ambystoma↗
PubMed2000

Interpregnancy interval as a risk factor for placenta accreta.

OBJECTIVE: To determine if the interval from a previous delivery or cesarean to the next conception differs between patients with abnormally adherent placentas as compared to those with normally implanted placentas. METHODS: We identified all histologically confirmed placentas--accreta, increta, and percreta--at our hospital from 1992-1999. Subjects were excluded for primigravidity in the affected pregnancy or inability to identify matched controls. Cases were matched to the next three consecutive women delivering for maternal age (> or = 35 years or < 35 years), placenta previa (yes or no), prior cesarean (yes or no), prior uterine curettage (yes or no), and prior vaginal delivery (yes or no). The primary outcomes were delivery-to-conception and cesarean-to-conception intervals. Secondary outcomes included measures of maternal and neonatal morbidity. RESULTS: Delivery-to-conception intervals for cases and controls were 37.1 +/- 18.7 months and 37.9 +/- 22.7 months, respectively (P = .91). Cesarean-to-conception intervals for cases and controls were 35.2 +/- 18.2 and 48.1 +/- 31.0 months, respectively (P = .35). Cases were more likely to require uterine curettage (54.5 vs 0%), hysterectomy (81.8 vs 0%), and transfusion (72.7 vs 0%), all P < .001. Subjects with accreta delivered earlier (31.7 +/- 9.4 vs 38.1 +/- 2.6 weeks, P = .054) and smaller infants (2,158 +/- 1,180 g vs 3,159 +/- 781 g, P = .006) who were more likely to have five-minute Apgar scores < 7 (18.2% vs 0%, P = .038). CONCLUSIONS: Cesarean-to-conception intervals but not delivery-to-conception intervals are shorter in patients with abnormally adherent placentas. Placenta accreta is associated with significant maternal and perinatal morbidity.

Adult↗
PubMed1997

[Liver transplantation in a small center: feasibility, efficacy and prospects].

Today, orthotopic liver transplantation is the treatment of choice for the end-stage of various liver diseases, and a 1-year survival rate of 80% and a 5-year survival rate of 70% in elective patients without tumor are reported in international surveys. The liver transplant programme of the Inselspital in Bern is small compared with international centres, which may raise questions about the results and the justification for such a programme. Over a period of 66 months, 62 liver transplantations were performed in 60 patients at the Inselspital. The hospital mortality was 3.3%, and the 2.5-year overall survival rate was 92% for elective cases without tumor. After a median follow-up of 30 months, 68% of all patients were re-integrated in housework or full- or part-time in their profession, and 83% were independent from the help of others. We conclude that a small liver transplant programme based only on routine resources can achieve results comparable to the international standards.

Academic Medical Centers↗
PubMed1997

Clonal descent and microevolution of Neisseria meningitidis during 30 years of epidemic spread.

Serogroup A meningococci of subgroups III, IV-1 and IV-2 are probably descended from a common ancestor that existed in the nineteenth century. The 10.5kb sequences spanning five distinct chromosomal loci, encoding cell-surface antigens, a secreted protease or housekeeping genes and intergenic regions, were almost identical in strains of those subgroups isolated in 1966, 1966 and 1917 respectively. During the subsequent two to three decades, all of these loci varied as a result of mutation, translocation or import of DNA from unrelated neisseriae. Thus, microevolution occurs frequently in naturally transformable bacteria. Many variants were isolated only once or within a single geographical location and disappeared thereafter. Other variants achieved genetic fixation within months or a few years. The speed with which sequence variation is either eliminated or fixed may reflect sequential bottlenecks associated with epidemic spread and contrasts with the results of phylogenetic analyses from bacteria that do not cause epidemics.

Alleles↗
PubMed1996

Allelic polymorphism and site-specific recombination in the opc locus of Neisseria meningitidis.

The opc gene is widespread in epidemic and endemic Neisseria meningitidis, but most strains of certain epidemic clones (ET-37 complex, Cluster A4) and a few random endemic isolates lack an opc gene. Four percent of the 1148 bp that contain opc plus the surrounding intergenic region was polymorphic (18 alleles), and many of the alleles contained a 230 bp insertion at a fixed location in the intergenic region. The presence or absence of the insertion reflects site-specific recombination. The alleles are stably inherited within clonal groupings for up to at least 50 years, with rare cases of horizontal genetic exchange. Most statistical methods indicated significant intragenic recombination events within this dataset.

Alleles↗
PubMed1995

Different hemodynamic effects of celipropol and atenolol in patients with mild to moderate hypertension.

The hemodynamic effects of celiprolol (CAS 56980-93-9), a betablocker with beta 1 antagonist and beta 2 agonist properties, were compared with those of atenolol (CAS 29122-68-7) in 12 patients with mild to moderately severe hypertension (diastolic BP 95-110 mmHg). Celiprolol and atenolol lead to a similar and significant reduction of systolic and diastolic blood pressure (p < 0.005). However, with celiprolol heart rate at rest was significantly less depressed then with atenolol (p = 0.004) and showed a distinctly less pronounced depression of heart rate with exercise (p = 0.004). Cardiac output at rest was reduced by 19% under atenolol, but was increased by 9% under celiprolol treatment; in this respect, the two medications differed significantly (p = 0.03). The adaptation of heart rate and cardiac output to exercise was better with celipropol as compared to atenolol treatment. The difference between arm arterial pressure and ankle occlusion pressure at rest was not significantly influenced by atenolol, whereas celiprolol treatment increased this difference by a mean of up to 16 mmHg (p = 0.009). This different effect on peripheral arterial circulation was even more pronounced after exercise. Both celiprolol and atenolol increased blood cell flow velocity in the nailfold capillaries, but this increases was statistically only significant with celiprolol (p = 0.047). These results demonstrate that the hemodynamic effects of celiprolol were significantly different from those of atenolol; celiprolol produces less bradycardia, increases cardiac output at rest and decreases peripheral arterial resistance.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1994

[Congenital heart defects: prevalence and course during the school years (8 to 16 years)].

In continuation of former studies regarding the first year of life and the preschool period, the prevalence and course of congenital heart disease in children during compulsory schooling has been studied. Compared with the preschool period, few cardiac defects are discovered, the prevalence up to 16 years of age being 9.9/1000. The mortality rate (2.7%) and also the rate of spontaneous normalization (4%) is significantly lower (compared to 18.7% and 21% respectively in the preschool period). Medical measures are needed less frequently, with 10 times fewer operations and 15 times fewer heart catheterizations being performed. Apart from the decline of hospital stays, checkups in the outpatient clinic also declined 3-4 times in comparison with the period between birth and school entry. School performance is very good. Only 4% of the children are unable to attend a normal school for cardiac reasons, and the percentage of pupils attending secondary school is higher than normal. In 5% of the children exercise tolerance is decreased due to the cardiac condition. In 85%, the quality of life is normal during the compulsory school period. Impairment is most often caused by additional non-cardiac malformations or very severe heart disease.

Abnormalities, Multiple↗
PubMed1994

Microevolution within a clonal population of pathogenic bacteria: recombination, gene duplication and horizontal genetic exchange in the opa gene family of Neisseria meningitidis.

Opacity (Opa) proteins are a family of antigenically variable outer-membrane proteins of Neisseria meningitidis. Even among clonally related epidemic meningococcal isolates, there is greater variation of Opa protein expression than can be accounted for by the opa gene repertoire of any individual strain. We characterized the opa genes of eight closely related isolates of serogroup A N. meningitidis (subgroup IV-1) from a recent meningitis epidemic in West Africa. DNA sequence analysis and Southern blot experiments indicated that changes occurred in the opa genes of these bacteria as they spread through the human population, over a relatively short period of time. Such changes in one or a few loci within a clonal population are referred to as microevolution. The distribution of sequences present in hypervariable (HV) regions of the opa genes suggests that duplication of all or part of opa genes into other opa loci changed the repertoire of Opa proteins that could be expressed. Additional variability in this gene family appears to have been introduced by horizontal exchange of opa sequences from other meningococcal strains and from Neisseria gonorrhoeae. These results indicate that processes of recombination and genetic exchange contributed to variability in major surface antigens of this clonal population of pathogenic bacteria.

Antibodies, Bacterial↗
PubMed1993

[Electron microscopic studies of fimbriae and lectin phagocytosis of Salmonella typhimurium variety copenhagen (STMVC)].

On Salmonella typhimurium variatio copenhagen (STMVC) strains, isolated from pigeons with acute Salmonellosis, two types of fimbriae can be identified, depending on different growth conditions. In addition to the common 7 nm fimbriae we were able to demonstrate in the electron microscope, thin, curled fimbriae 3 nm in diameter which are characterized by a mannose-resistant hemagglutination. The simultaneous expression of both types of fimbriae on a single bacterial cell can be induced by transferring a microcolony from agar medium (3 nm fimbriae), to the surface of a nutrient broth (7 nm fimbriae) and continuing the incubation. One selected strain expresses only the thin fimbriae on nearly all the bacteria on an agar medium. These thin fimbriae seem to play a role in the lectinophagocytosis in macrophage cultures. The attachment of Salmonellae mediated by these fimbriae as well as the internalization of fimbriated cells by macrophages is shown in the electron microscope and discussed in respect to infection and immunization.

Animals↗
PubMed1990

[Molecular biologic methods for epidemiological precision characterization of disease agents using Salmonella enteritidis from poultry as an example].

The principles of molecular biological methods for epidemiological investigation of infectious bacteria are described. They were applied for differentiating S. enteritidis isolates originating from poultry. Among the methods described are the determination of the chromosomal DNA fingerprints (BRENDA), the methods of multilocus enzyme electrophoresis, plasmid profiles, and the outer membrane protein as well as lipopolysaccharide pattern. It turned out, that S. enteritidis strains isolated before 1987, in 1988 and the ones originating from Great Britain did not differ in anyone of these criteria. Consequently one has to assume, that the strains recently causing problems originate from the population of S. enteritidis which had existed in poultry before.

Animals↗
PubMed1989

[Colonoscopy: indications, procedure, results].

Colonoscopy in childhood is indicated as a valuable procedure mainly in rectal bleeding and suspected inflammatory bowel disease. Because of high efficiency and low complication rates this procedure should be used more often.

Adolescent↗
PubMed1987

[Sonographic diagnosis of solid space-occupying abdominal lesions in childhood].

Between 1981 and May 1986 31 children with solid abdominal tumor masses were observed in our clinic. The first diagnostic procedure was a sonographic examination, followed by further radiological investigations if necessary. 30 cases were examined histologically; in one case the sonographic findings were confirmed by an angiography. The most frequent abdominal masses were neuroblastomas and Wilms tumors (7 cases each). A mesoblastic nephroma was diagnosed in 3 cases, a lymphoma, a hepatoblastoma and a rhabdomyosarcoma 2 times each. One time we found a pancreas carcinoma, a teratoma, a hemangiomatosis of the liver, a malignant Schwannoma, a Ewing sarcoma, an adenoma of the adrenal gland, a pheochromocytoma and an osteosarcoma. According to our own experience and recent reports in the literature it seems possible in most cases, to predict the correct diagnosis of solid abdominal masses using the informations of sonographic imaging. Sonography is a highly specific non-invasive diagnostic tool for planning treatment (e.g. early surgery, cytostatic therapy and/or radiation) of solid abdominal masses. Nevertheless the histological examination should be performed in every case to confirm the definitive diagnosis.

Abdominal Neoplasms↗
PubMed1986

The mom gene of bacteriophage Mu: the mechanism of methylation-dependent expression.

Transcription of the DNA modification gene (mom) of bacteriophage Mu requires methylation of three GATC sites upstream of the mom promoter by the Escherichia coli deoxyadenosine methylation function (Dam). The three sites map within a 40-bp segment termed region I. Small deletions, inversions, duplications and specific point mutations have been introduced in region I. Their effect on mom expression has been studied in dam+ and dam strains. Dam-dependent expression of the mom gene requires a specific arrangement of the three GATC sites and the presence of the methylated base in at least two of the three sites. We show that mom specific modification is regulated by a host protein. The Mom function is expressed in dam strains if they are defective in one component of the methylation-instructed mismatch correction system, mutH. We suggest that the product of mutH functions as a transcriptional repressor by binding to region I.

Base Sequence↗
PubMed1986

Epidemiology and chromosomal location of genes encoding multiresistance in Salmonella dublin.

Multiresistant Salmonella dublin strains isolated between 1971 to 1984 were investigated for their genetic and physical properties. It turned out that the multiresistance of the 1971 to 1973 isolates was plasmid-encoded. In the following years, however, the plasmid profiles of the strains were indistinguishable from sensitive isolates and the genes encoding the multiresistance were located on the Salmonella chromosome.

Chromosome Mapping↗
PubMed1985

The mom gene of bacteriophage mu: a unique regulatory scheme to control a lethal function.

The mom gene of bacteriophage Mu encodes a DNA modification function which converts adenine to acetamido adenine in a sequence-specific manner. The mom gene itself is subject to a complex regulation: gene expression requires methylation by the Escherichia coli Dam methylase of specific sites upstream of the mom promoter and transactivation of the promoter by a Mu gene product. The requirement for transactivation can be overcome when mom is transcribed from foreign promoters. When cloned into various sites in pBR322, the mom gene is always found in an orientation where transcription from vector promoters is excluded. The productive orientation is lethal to the cell. This effect is mediated by the concerted action of the mom gene product and the product of gene com (control of mom, previously termed ORF-x) whose coding region overlaps the 5-coding region of the mom gene. When mom is expressed from its own promoter, internal deletions in com completely abolish expression of the mom gene. Fragments lacking the 5' end of com can be cloned downstream of constitutive plasmid promoters. The com gene product itself is not lethal to the cell. The region encoding mom has been cloned in pL expression vectors. The mom gene product, a peptide of 27 kDal, has been visualized on gels. Efficient expression of Mom from pL requires gene com. A fusion between MS-2 polymerase and com has been generated. The fusion product is made in large amounts, whereas the mom gene product is not overproduced although the gene is present on the same transcriptional unit.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriophage mu↗
PubMed1984

Renal glycosuria in patients with the nephrotic syndrome.

Transient or persistent renal glycosuria may occur in patients with the nephrotic syndrome. In an attempt to elucidate its mechanism, glucose titration experiments were performed in 20 nephrotic patients. The type A titration curve was found in one and type B in four patients with severe organic changes and low glomerular filtration rate. The remaining subjects displayed a particular type of curve (type C) characterized by a low point of splay but an otherwise almost physiological tracing. In type B and C patients the maximal rate of reabsorption per ml glomerular filtrate (TmG/GFR) was significantly increased and correlated inversely with the filtration fraction. In these patients the point of splay correlated with the glomerular filtration rate and the sodium clearance, but not with the plasma albumin concentration or the rate of proteinuria. These observations suggest that type A was due to diffuse tubular atrophy, and type B to increased nephron heterogeneity resulting from chronic organic changes. Type C was presumably caused by a potentially reversible alteration of the late proximal or distal glucose transport related to the nephrotic syndrome itself.

Adolescent↗