Search PubMed⌕ Search

Biomedical subjects

S Otto

Publications and source records attributed to S Otto.

At least 37 records · Page 2Linked to original sources
PubMed1999

Genetic dissection of X-linked interspecific hybrid placental dysplasia in congenic mouse strains.

Interspecific hybridization in the genus Mus results in male sterility and X-linked placental dysplasia. We have generated several congenic laboratory mouse lines (Mus musculus) in which different parts of the maternal X chromosome were derived from M. spretus. A strict positive correlation between placental weight and length of the M. spretus-derived part of the X chromosome was shown. Detailed analysis was carried out with one congenic strain that retained a M. spretus interval between 12.0 and 30.74 cM. This strain consistently produced hyperplastic placentas that exhibited an average weight increase of 180% over the weight of control placentas. In derived subcongenic strains, however, increased placental weight could no longer be observed. Morphometric analysis of these placentas revealed persistence of abnormal morphology. Fully developed placental hyperplasia could be reconstituted by recombination of proximal and central M. spretus intervals with an intervening M. musculus region. These results may suggest that placental dysplasia of interspecific mouse hybrids is caused by multiple loci clustered on the X chromosome that act synergistically. Alternatively, it is possible that changes in chromatin structure in interspecific hybrids that influence gene expression are dependent on the length of the alien chromosome.

Animals↗
PubMed1998

Dissolution of multicomponent microbubbles in the bloodstream: 2. Experiment.

The effect of the nature of the filling gas on the persistence of microbubbles in the bloodstream was studied. All the microbubbles were covered with the same shells. Various perfluorocarbons and perfluoropolyethers alone and as mixtures with nitrogen were used as the filling gases. The persistence time of microbubbles in the bloodstream tau increased with the molecular weight of the filling gas, from approximately 2 min for perfluorethane, to > 40 min for perfluorodiglyme, C6F14O3, and then decreased again to 8 min for C6F14O5. An acceptable ultrasound scattering efficacy was exhibited by the filling gases with intermediate molecular weights that possessed both a high saturated vapor pressure and a comparatively low water solubility (Ostwald coefficient). On the basis of the experimental data, it is concluded that the microbubble persistence tau is controlled primarily by the dissolution of microbubbles and not by the removal of the microbubbles by the reticular endothelial system. Although the qualitative experimental trends are in good agreement with the theoretical model developed previously, there are some quantitative differences. Possible reasons for these differences are discussed.

Air↗
PubMed1998

Neonatal fulminant hepatitis B: structural and functional analysis of complete hepatitis B virus genomes from mother and infant.

Transmission of hepatitis B virus (HBV) from anti-hepatitis B e (anti-HBe)-positive carrier mothers to their infants may result in neonatal fulminant hepatitis B (FHB). We investigated whether HBV variants with a particular DNA sequence and functional phenotype, responsible for FHB, are selected during transmission. Full-length HBV genomes from a mother-infant pair were completely sequenced and transfected into human hepatoma cells. The dominant neonatal and maternal HBV populations were nearly identical (homology 99.8%) and showed a precore stop codon mutation, T-1762 and A-1764 substitutions in the core promoter region, and pre-S2 start codon mutations. Cells transfected with variants from mother and child, compared with wild-type virus, synthesized and released a similar number or fewer HBV DNA-containing particles. In conclusion, no particular HBV strain emerged during neonatal FHB. In this case, a de novo infection with variants showing a defect in HBe antigen and pre-S2 protein synthesis but not a high replication competence probably contributed to the fulminant disease course.

Adult↗
PubMed1997

A new class of defective hepatitis B virus genomes with an internal poly(dA) sequence.

Sequence heterogeneity of hepatitis B virus (HBV) is increasingly recognized to play a role in virus-host interaction. We have used a recently established method for HBV full-length genome amplification to search for novel types of HBV variants and to investigate further the sequence heterogeneity of HBV genome populations. Using this method, a substantial fraction of HBV genomes much shorter than wildtype size was found in some sera and liver biopsies from infected patients. Cloning and sequencing of a number of these HBV genomes as well as hybridization studies revealed a new minor class of HBV genomes with an internal poly(dA) sequence approximately 60 to more than 100 nucleotides long in 4 of 10 patients. The 5'-ends of the internal poly(dA) sequences are located at positions corresponding to the authentic processing/polyadenylation sites of the RNA pregenome, whereas the positions of the 3'-ends are variable due to different sizes of adjacent deletions. These data suggest that the poly(A) tail of the pregenomic RNA is occasionally reverse transcribed by the HBV P-protein and during this process a deletion seems to be introduced into the DNA minus strand. We propose a mechanism by which this could be accomplished during DNA minus strand synthesis.

Base Sequence↗
PubMed1997

[Dying and death in an acute-care medical hospital].

Nowadays, more people seem to die in hospitals or other establishments than in their own homes. The following paper reports on 50 consecutive cases of death that occurred in a clinic of internal medicine. The analysis concentrated on the circumstances, the symptoms and the treatment of the patients during the 12 h. preceding and immediately before death as well as on the opinion of the relatives and the attending staff. A questionnaire registered the different opinions. Nearly a third of these deaths occurred after a fairly short hospitalization time. Death was not always the result of a long illness and it involved also young people. Most of the patients died in their hospital room, in the presence of their relatives and/or of the attending staff. They were mostly unconscious during the moments preceding their death. Terminal symptoms such as pain, anxiety, shortness of breath or thirst were largely kept under control. The relatives and concerned people were, as far as possible, informed about the grievance and the fatal issue of the patient's illness. Their reactions were diverse. Most relatives were satisfied with the treatment and care given to the hospitalized patient. The doctors and nursing staff considered their working together as being better than usually expected. Clear therapeutical concepts, appropriate palliative care as much as optimal communication are important requirements for a good treatment of the dying. The following results allow us to question many a prejudice concerning death in a hospital surrounding, but also show us possibilities of improvement. So we should sometimes question ourselves about the sense and the need of certain nursing interventions. We should spend more time during our medical training on the question of palliative care and on the problem of the relationship of doctors to death and to the dying. We feel that establishing a "science of death" or a segregation of the dying in specialized institutions makes no sense.

Adult↗
PubMed1996

[Effectiveness and tolerance of a polyvidon substance in treatment of dry eye syndromes].

BACKGROUND: Insufficient wetting of the ocular surface is very frequent. Artificial tears are commonly used for therapy. The influence on symptoms and tolerability of a product formulated with polyvidon and electrolytes resembling natural tears were investigated. METHOD: Efficacy and local tolerability of a polyvidon (polyvinylpyrrolidon) formulation in the treatment of the "dry-eye" syndrome were tested in an open multicenter study on 586 patients with dry-eye conditions of various etiology. Patients were treated under the conditions of daily usage with the tear substitutes Oculotect fluid or Oculotect fluid sine which are formulations with electrolytes in a composition which resembles natural tears. The duration of treatment was 8 weeks and application frequency was dependent on severity of dry-eye syndrome. The therapeutic effect was evaluated before treatment and after one, four and eight weeks by tear film break-up time (BUT test). Schirmer-I test and by ratings of patient's self assessment of their complaints. Additionally patients general and ophthalmological history was recorded. RESULTS: Before the start of the treatment the BUT test and Schirmer-I test yielded mean values of 9.0 (+/-5.2) sec and 6.2 (+/-3.8) mm respectively. These values increased over the course of the approximately 8-week treatment period to 12.3 (+/-5.6) sec and 10.1 (+/-4.8) mm respectively. Both parameters increased as highly significant (p < or = 0.0001, Wilcoxon-Test). Before treatment patients rated the following complaints as medium strong or strong: sensation of foreign body (66%), burning (69%), sensation of pressure (48%) and/or conjunctival hyperemia (48%). Some 8 weeks later, only 5% (sensation of foreign body), 8% (burning), 5% (sensation of pressure) and 6% (conjunctival hyperemia) of the patients with all examination time points rated these complaints similarly. The efficacy and tolerability were rated by the ophthalmologist on visual analog scales (minimum 0, very poor to a maximum of 100, very good). The average efficacy rating was 72.9 (+/-21.5), Oculotect fluid and Oculotect fluid sine were rated practically identically. The tolerability was rated high at 81.6 (+/-17.6). Reports of undesirable side-effects were given by 15 patients (3%), none of these side-effects were serious. CONCLUSIONS: In patients typically met in ophthalmologists' office, treatment with preserved or unpreserved artificial tear with polyvidone resulted in distinct improvement of their complaints.

Adolescent↗
PubMed1995

Expression of a novel integrin beta 1 chain epitope and anti-beta 1 antibody-mediated enhancement of fibronectin binding are dependent on the stage of T cell differentiation.

Beta 1 integrins are a family of alpha beta heterodimers that serve as cell surface receptors for extracellular matrix proteins. We demonstrate that the anti-mouse integrin beta 1 chain mAb KMI6 selectively recognizes a beta 1 epitope that is constitutively expressed by certain immature thymocytes and is induced only slightly on mature thymocytes and peripheral T cells by activation with Con A. Because virtually all cells examined expressed beta 1 integrins on their surface, expression of the KMI6 epitope is T cell differentiation stage specific. Most CD3-4-8- thymocytes were KMI6+, with the lowest level of staining observed on the earliest CD44+IL-2R- cells within this subset. Expression was down-regulated during the CD3-4-8- to CD3-4-8+ transition, and lost by the CD4+8+ stage. Mature single positive thymocytes and resting peripheral T cells were also KMI6-. In contrast with the loss of the epitope before TCR expression by other thymocytes, most CD3+4-8- and certain CD8+ gamma delta TCR+ thymocytes were KMI6+ Addition of KMI6 to cell adhesion assays enhanced CD4-8- thymocyte, but not activated mature thymocyte or peripheral T cell, binding to fibronectin (via alpha 4 beta 1 and alpha 5 beta 1), whereas laminin binding (via alpha 6 beta 1) was unaffected. These properties distinguish the KMI6 epitope from other epitopes involved in beta 1 integrin activation in mice and other species. The unique selectivity of KMI6 recognition of beta 1 integrins, and its selective enhancement of ligand binding suggest that beta 1 integrin structure and factors that regulate beta 1 integrin binding are correlated with the stage of T cell differentiation.

Animals↗
PubMed1995

Alpha 3 beta 1 and alpha 6 beta 1 integrins mediate laminin/merosin binding and function as costimulatory molecules for human thymocyte proliferation.

Integrins comprise a superfamily of alpha beta heterodimers that serve as cell signaling as well as adhesion molecules. We demonstrate that the alpha 3 beta 1 and alpha 6 beta 1 integrins are laminin/merosin receptors expressed in human thymocytes. By reverse transcriptase-PCR analysis, we determined that the alpha 3A beta 1, but not the alpha 3B beta 1, cytoplasmic structural variant of alpha 3 beta 1 is expressed in thymocytes. In contrast, both alpha 6A beta 1 and alpha 6B beta 1 cytoplasmic structural variants of alpha 6 beta 1 are expressed. A small percentage (10 to 15%) of human thymocytes bind to immobilized laminin, and even fewer (3 to 5%) bind to merosin, the laminin isoform normally present in the thymus. This binding, however, can be increased to 39 to 41% after activation of thymocytes with Mn2+ (or PMA). Binding to either laminin or merosin is completely inhibited by anti-beta 1 mAb or by a mixture of anti-alpha 3 and anti-alpha 6 mAbs, indicating that both alpha 3 beta 1 and alpha 6 beta 1 participate in thymocyte adhesion to the laminin family of extracellular matrix proteins. The protein kinase C inhibitors, calphostin C and staurosporine, inhibit Mn(2+)-enhanced thymocyte binding, suggesting that protein kinase C activity is crucial for the binding. Furthermore, the data indicate that at least two divalent cation binding sites serve to regulate integrin binding activity. Finally, we show that both immobilized laminin and merosin have costimulatory function for anti-CD3-induced thymocyte proliferation, and both anti-alpha 3 and anti-alpha 6 mAbs can block this proliferative response. The cooperative function of alpha 3 beta 1 and alpha 6 beta 1 evidenced in the laminin/merosin binding and proliferation assays suggests that thymocyte-merosin interactions may play an important role in thymic T cell development.

Base Sequence↗
PubMed1995

Marked changes of arginine vasopressin, oxytocin, and corticotropin-releasing hormone in hypophysial portal plasma after pituitary stalk damage in the rat.

Mechanical compression of the pituitary stalk with the help of a blunt stereotaxic knife results in posterior pituitary denervation (PPD) and sprouting proximal to the injury, leading to formation of an ectopic neurohypophysis in the stalk. This provides an experimental model for those cases in which traumatic damage severs the nerve fibers to the neural lobe but does not obliterate the hypophysial-portal circulation. The effect of PPD on the hypophysial-portal concentration profile of putative ACTH secretagogues as well as basal and stimulated ACTH secretion in vitro were investigated at varying times after PPD. The contents of arginine vasopressin (AVP) and oxytocin (OT) in extracts of the stalk median eminence 1 week after PPD were markedly elevated, whereas corticotropin-releasing hormone (CRH) content was unaffected. Levels of these three neuropeptides in hypophysial-portal blood collected under anesthesia from the proximal stump of the transected stalk (or the ectopic neural lobe) were measured at weekly intervals in groups of rats after sham or PPD surgery. Hypophysial-portal AVP levels showed a monotonic increase with time after PPD from a 1.8-fold elevation at 1 week post-PPD to a maximum concentration 6-fold greater than that in sham groups at 4 weeks post-PPD. Portal plasma OT levels also exhibited extreme elevation. In contrast, portal plasma CRH levels showed an initial 72% decline 1 week post-PPD. We suggest that mechanical damage to the pituitary stalk and the subsequent sprouting redirected secretion of AVP and OT from the neural lobe to the pituitary stalk. This caused sustained elevations of portal plasma concentrations of AVP and OT. The resulting tonic exposure to AVP and/or OT may down-regulate anterior pituitary receptors to these neurohypophyseal peptides and indirectly decrease CRH release into the portal circulation.

Adrenocorticotropic Hormone↗
PubMed1995

Multichannel auditory brain stem implant: case studies comparing fitting strategies and results.

A new 8-electrode prosthesis has been developed for individuals deafened by bilateral auditory nerve tumors (neurofibromatosis-2). Twelve patients have received the multichannel auditory brain stem implant at House Ear Institute since 1992, 11 of whom receive useful auditory sensations. Processor fitting includes scaling and ranking of electrode-specific pitch sensations, and determination of any nonauditory sensations. Two representative patients differing in experience and number of usable electrodes are compared in terms of range of auditory sensations and speech perception performance. An inexperienced patient with two electrodes using a new speech-processing strategy (Speak) performed comparably to an experienced patient with six electrodes using an earlier feature-extraction processor.

Adult↗
PubMed1994

[Hormonal and biochemical characterization of breast cyst fluid in gross cystic mastopathy].

A total of 93 breast cyst fluids (BCF) obtained by needle aspiration of women suffering from gross cystic mastopathy was hormonally investigated. The mean age of the patients was 45 years (range 27-65). Estradiol (E2), progesterone (PROG), testosterone (TE), prolactin (PROL), estriol (E3), dehydroisoandrosterone and its sulfate (DHA, DHA-S) levels were investigated in the BCF and in the respective sera. Tumour marker beta-HCG and CA 15-3 as well as cations (K+, Na+) were determined, too. E2, E3, PROG, TE, PROL, DHA, DHA-S and K+ showed significant accumulation in the BCF compared to the serum values. The K+/Na+ ratio proved to be a useful tool to divide cysts into type I (> or = 1), type II (< 1 but > or = 0.1) and type III (< 0.1) subgroups. In case of type I BCF, higher E2, DHA, DHA-S and PROL levels could be detected, while PROG and TE contents proved to be the highest in type II cysts. These findings indicate that the type I BCF is a marker for "active" GCD of the breast and suggest that it may be associated with increased breast cancer risk. It is suggested therefore when macrocysts are aspirated, sex steroids, steroid hormone precursors and cations in the BCF should be examined routinely, and women with type I cysts should be controlled carefully.

Adult↗
PubMed1994

Environmental behavior of bentazon herbicide.

Bentazon is a postemergence herbicide used in early spring to early summer in many crops, usually at application rates of 1.0 kg a.i./ha. Its selectivity is based on the ability of the crop plants to metabolize bentazon quickly to 6-OH- and 8-OH-bentazon and conjugate these with sugars, while weeds do not, so that photosynthesis is disrupted and the weeds die. Also, there is a further degradation to small fragments, which subsequently are incorporated into natural plant products. Residues in the raw agricultural commodities range from 0.1 to approximately 1.0 mg/kg (straw and other "leftover" plant parts). In the upper soil layer, bentazon is quickly degraded, microbially and aerobically, via the intermediary and instable products 6-OH-, 8-OH-bentazon, and AIBA. These are immediately bound biotically and abiotically to the mostly nonbioavailable soil organic matter fraction. Additionally, a considerable part (24-50%) is mineralized to CO2. Half-lives in field soils ranged from 3 to 21 d with an average of 12 d. Abiotic degradation processes predominantly involve photolyses on plant and soil surfaces and in surface water. The physical-chemical properties and soil column laboratory studies with bentazon would seem, at first glance, to predict a leaching potential. However, several field lysimeter studies unambiguously proved that it does not leach under field situations. Annual averages in the leachates were always < 0.1 microgram/L, also after the second year. Reasons for the favorable field behavior, in contrast to the laboratory studies, are discussed. Reports on bentazon findings in groundwater and drinking water were classified as resulting predominantly from former filtrate along Rhine banks. Since 1988, the bentazon levels in the Rhine River ranged below or near 0.1 microgram/L. Very few isolated point-source contaminations, arising from accidents and other reasons, are marked by sporadic findings of concentrations > 1 microgram/L. Nonvalidated findings at various locations are reported that lie below or near the determination limit. In such situations, it is highly recommended to identify bentazon with a "full" MS-spectrum. The ecotoxicological effects of bentazon lead to "no classification necessary." The small octanol/water partition coefficient precludes bioaccumulation. Bentazon is rapidly excreted by warm-blooded animals without any uptake of residues in edible tissues. Based on its toxicological properties, bentazon was classified as noncarcinogenic ("Group E") by the EPA. The ADI is set at 0.1 mg/kg body weight/d. The WHO drinking water guideline value, based on the toxicological profile of bentazon, was recently raised to 30 micrograms/L.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

[Different opioids in patients at cardiovascular risk. Comparison of central and peripheral hemodynamic adverse effects].

Efficient analgesia may be the major objective in the cardiovascular risk patient following myocardial infarction, acute occlusion of peripheral vessels, or dissection/perforation of major abdominal vessels. It was the purpose of the study to investigate the haemodynamic and respiratory side effects of eight different opioids in 57 circulatory risk patients prior to major vascular surgery. METHODS. Patients were randomly allocated to eight groups, each receiving a different opioid within a clinical, equipotent dose range (buprenorphine, fentanyl, morphine, nalbuphine, pentazocine, pethidine, tramadol, alfentanil). A complete haemodynamic and blood gas status was obtained prior to as well as 5, 10, 15, and 20 min following opioid administration. Monitoring included a complete invasive haemodynamic and blood gas status. Statistical evaluation was performed by 1- and 2-factorial ANOVA (P < 0.05). RESULTS. Significant time effects (changes from baseline at the time of measurement) were observed for heart rate and total peripheral resistance, while significant group (group-specific differences in the course of values at the different times of measurements) and time effects were noted for mean pulmonary artery pressure, pulmonary capillary wedge pressure, stroke volume index, and PaO2. No major effects were observed following morphine, fentanyl, alfentanil, tramadol, and nalbuphine. Buprenorphine caused distinct respiratory depression accompanied by an increase in pulmonary vascular tone. Pentazocine and pethidine caused a significant increase in MPAP and peripheral vascular resistance while pethidine also produced marked respiratory depression. CONCLUSIONS. For interpretation of the results, factors such as respiratory depression, histamine release, secretion of endogenous catecholamines, and hypoxia-induced pulmonary vasoconstriction have to be discussed. Tramadol, an opioid with moderate potency, seems to offer some advantages due to its minor cardiovascular and respiratory side effects.

Aged↗