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Biomedical subjects

A Nolte

Publications and source records attributed to A Nolte.

At least 37 records · Page 2Linked to original sources
PubMed1996

Mirror-image RNA that binds D-adenosine.

A 58-mer L-RNA ligand that binds to naturally occurring D-adenosine with a dissociation constant of 1.7 microM in solution was identified from a combinatorial library employing mirror-design. The corresponding D-RNA ligand shows identical binding affinity to L-adenosine. Reciprocal chiral specificity was also evident from ligand discrimination; the binding affinity of the L-RNA ligand for D-adenosine was 9000-fold greater than its affinity for L-adenosine and vice versa. While the D-RNA ligand was rapidly degraded in human serum, the L-RNA ligand displayed an extraordinary stability. This indicates the potential application of specifically designed L-RNA ligands as stable monoclonal antibody analogues and the development of highly stable L-ribozymes.

Adenosine↗
PubMed1996

Mirror-design of L-oligonucleotide ligands binding to L-arginine.

The high affinity and selectivity of nucleic acid ligands have clearly demonstrated that RNA can be targeted to a variety of molecules. In practice, however, the use of unmodified aptamers is impeded by the low stability of RNA in biological fluids. Here we describe the mirror-design of a stable 38-mer L-oligoribonucleotide ligand that binds to L-arginine. This L-RNA ligand was also able to bind to a short peptide containing the basic region of the human immunodeficiency virus type-1 Tat-protein. The L-RNA ligand displayed the expected stability in human serum. These findings may contribute to the identification of novel diagnostics and pharmaceuticals.

Amino Acid Sequence↗
PubMed1996

[Nurses' and patients' experience of combined health service delivery to all population groups in a hospital].

In a community hospital in Gauteng, the hospital management had, on short notice, to provide combined health services to all population groups. In the past different health services were delivered to each population group. The integration of health service delivery was a sudden change. Based on this, research questions arose, namely: how do nurses and patients experience this change, and how could they be assisted to adjust to the change. The research objectives were twofold, namely: to explore and describe nurses and patients' experience of combined health delivery to all population groups and based on the results to make recommendations to assist them with adjustment to a combined health delivery system. An exploratory, descriptive and contextual research design was followed. Trustworthiness was ensured by applying Guba's approach. Phenomenological and individual focus interviews were conducted with forty nurses and patients who were selected purposively. Field notes were written after completion of each interview. The transcribed data was analysed by using Giorgi's and Kerlinger's methods combined. Results were discussed and a literature control completed. The most important conclusions reached were: there was an insufficient administrative structure in the hospital as a result of insufficient preparation for the combined health service delivery for all population groups; the whites' perception of different populations groups is based on an ethnocentric Western approach. This led to their experience of culture shock that resulted in feelings of anger/frustration, fear and sadness; the willingness of other populations groups to adjust to combined health service delivery led to their experience of happiness; there exists communication problems between population groups because of their not being able to communicate in their own language and the difference in communication styles; the verbalised Christian viewpoint and values of whites nurses and patients are not congruent with their prejudiced perception of people of other population groups and cultures, and the different population groups do not know each other's lifeworlds and that leads to prejudices that block open communication. Several recommendations were made based on these conclusions.

Black or African American↗
PubMed1995

Crystallization and preliminary diffraction studies of the structural domain E of Thermus flavus 5S rRNA.

The ribosomal 5S RNA is an essential constituent of the large ribosomal subunit. To overcome the difficulties of crystallizing large RNA molecules such as 5S rRNAs, we decided to divide the 5S rRNA in five domains A through E to determine their structure. Recently we determined the crystal structural of the helical domain A. Here we report the crystallization of the chemically synthesized domain E of the Thermus flavus 5S rRNA. The crystal form is trigonal with unit cell dimensions: a = b = 42.80 A and c = 162.20 A. Diffraction-data to 2.8 A have been recorded and the structure solution is currently underway by means of MIR and MAD techniques.

Base Sequence↗
PubMed1995

Differences between the practice of nurses and midwives.

It is often claimed by midwives that they have an unique role which is complementary to but different from the roles of other health care professionals. Most of the studies done in midwifery so far lack clarity of definition and distinction with regard to process as well as contents. It is important to describe the functions of a midwife clearly, because the absence of a clearly defined sphere of practice creates problems in the development of an appropriate curriculum. The aim of this study is to describe the unique functional activities of midwives and compare it with those of the nurse.

Humans↗
PubMed1994

Short- and long-term effects of neonatal diazepam exposure on local cerebral glucose utilization in the rat.

The short- and long-term consequences of a neonatal exposure to diazepam (DZP) on the postnatal changes in local cerebral metabolic rates for glucose (LCMRglcs) were studied by the quantitative autoradiographic [14C]2-deoxyglucose method in a total number of 66 brain structures of freely moving rats. Rat pups received a daily subcutaneous injection of 10 mg/kg DZP, of the dissolution vehicle or of saline from postnatal day 2 (P2) to 21 (P21). The animals were studied at 4 ages, P10, P14, P21 and P60. DZP induced a decrease in LCMRglcs which was restricted to 13 areas at P10, mainly sensory and limbic regions. At P14, the treatment had significant metabolic effects on 48 structures belonging to all functional systems. By P21, 23 brain areas were still affected by the treatment, mainly sensory, limbic and motor areas. At P60, i.e. at about 40 days after the end of drug exposure, LCMRglcs still decreased in 14 brain regions which were mainly sensory and limbic structures. The structures most sensitive to both short- and long-term consequences of the anticonvulsant treatment are mammillary body, limbic cortices and sensory regions. The dissolution vehicle increased LCMRglcs in a few brain regions at P14 and P60, whereas it decreased metabolic levels in 5 brain regions at P21. The results of the present study show that the brain appears to be particularly vulnerable to the treatment at P14, period of active brain growth, whereas by P21, the drug is actively metabolized and a tolerance to the treatment may occur. The long-term effects of the treatment are in good accordance with the well-known effects of DZP on anxiety, sedation and memory. The structures most sensitive to early neonatal DZP exposure are the mammillary body, limbic cortices and sensory regions that all contain a high density of benzodiazepine binding sites.

Aging↗
PubMed1994

Interleukin-1 beta (IL-1 beta) binds to intact porcine thyroid follicles, decreases iodide uptake but has no effect on cAMP formation or proliferation.

Interleukin-1 beta (IL-1 beta) is known to be involved in autoimmune thyroiditis. Since the results of different in vitro-studies on the effect of IL-1 on thyrocytes are controversial, our aim was to investigate the existence of specific binding sites for IL-1 beta and its influence on specific functions and growth of isolated porcine thyroid follicles ex vivo with a preserved iodide metabolism. For binding studies isolated thyroid follicles were incubated with 125I-IL-1 beta (213.5 nCi/ml) and with increasing concentrations of unlabelled IL-1 beta (0.06-11.5 nmol/l) for 24 h at 4 degrees C. The dissociation constant Kd was 0.85 x 10(-10) mol/l and about 800 binding sites per cell were calculated. IL-1 beta (10 U/ml) decreased basal and TSH-stimulated iodide uptake and organification after an incubation time of 45 min to 6 h without any influence on cAMP-formation. In addition, after 40 h of incubation IL-1 beta dose-dependently increased T3-secretion, followed by a decrease during simultaneous TSH-stimulation, whereas there was no effect on T4-secretion. In contrast to these functional effects IL-1 beta showed no influence on the growth of thyroid follicles, so that the cytokine cannot be made responsible for goiter growth in thyroid diseases by directly influencing thyroxytes.

Animals↗
PubMed1994

[The midwife in South Africa. Part I--The practice of the midwife].

Part 1, of a two part series on the dilemma of the midwife in South Africa, deals with the practice of the midwife. It is difficult to estimate the number of practicing midwives, as they form part of the general nursing register. Also midwifery is part of the basic nurse training and is not taught as a separate entity. The midwife in South Africa practices in the areas of primary health care, hospitals, clinics, mobile clinics, homes and MOU's. The governments commitment to PHC will likely result in most midwives practicing in this area. Problems are high maternal deaths, shortages and maldistribution of midwives in an urban/rural context and the fragmentation and poor coordination of the health services. The safe motherhood initiative of the WHO has been adopted, there are recommendations that midwifery education be separated from general nurse education, and that clinical skills be strengthened. Midwifery services in South Africa do not fulfill the basic criteria for a PHC service.

Humans↗
PubMed1993

[Disorders of eye movements in schizophrenia--a critical review and future perspectives].

Disorders of smooth pursuit eye movements and saccadic eye movements have been reported frequently in schizophrenics. Probably 50% of the schizophrenic probands and of their unaffected relatives perform abnormal smooth pursuit movements. These deficiencies have been regarded as a possible genetic trait marker for schizophrenic vulnerability. Saccadic eye movements have been investigated less intesively. The most prominent pathological feature is a lack of precision of reflexive saccades in case of schizophrenic probands. Although a large body of research has been conducted, the multitude of the results of eye movement disorders in schizophrenics and also technical and methodological problems impair the significance of these findings. In this review, the most important results are critically elaborated and research perspectives are pointed out. A valid identification of eye movement abnormalities is necessary.

Humans↗
PubMed1993

Human neutrophil elastase increases permeability of cultured pulmonary endothelial cell monolayers.

Polymorphonuclear leukocytes (PMN) contribute to increased pulmonary vascular permeability in inflammatory lung injury, but the mechanism of their action is complex. In the present study we examined possible effects of PMN-derived proteases on the permeability of pulmonary endothelial cell monolayers grown on polycarbonate filter membranes and exposed continuously to a hydrostatic pressure of 10 cm H2O. Cell- and serum free PMN-supernatants (human PMN, stimulated with 30 ng/ml phorbol-myristate acetate for 30 min, presence of catalase, were centrifuged, the supernatants were passed through a 0.45 micron filter) dose-dependently (calculated PMN: endothelial cell ratio of 2:1 and more) increased hydraulic conductivity of endothelial cell monolayers ten- to twentyfold within 20-70 min. At the same time the dextran reflection coefficient decreased from 0.8 to 0.1. Phase contrast and scanning electronmicroscopy showed a widening of intercellular gaps. The effects of the postsecretory PMN-supernatant were blocked dose-dependently by inhibitors of human neutrophil elastase (HNE) but not of cathepsin G. On quantitative grounds highly purified HNE was similarly active as postsecretory PMN supernatant. The effects of HNE were inhibited by pretreatment with eglin-c or heat, but not with heparin. The data suggest that HNE is an effective and sufficient neutrophil-derived mediator to increase endothelial permeability. HNE appears to act primarily enzymatically and not as a cationic protein.

Amino Acid Sequence↗
PubMed1992

Abnormal length of cilia--a cause of primary ciliary dyskinesia--a case report.

A 7-year-old Turkish boy had suffered from chronic coughing from early childhood. Severe bronchiectasis in the right lung was confirmed by bronchography. Ciliary beat frequency determined in a bronchial mucosal biopsy was markedly decreased (5.7 Hz). Electron microscopy revealed cilia with a length of 15 microns. No structural abnormality was found. A possible link between the abnormally long, slow beating cilia and the clinical symptoms is discussed.

Bronchi↗
PubMed1988

Transport systems for amphipathic compounds in normal and neoplastic hepatocytes.

Photoaffinity labeling of plasma membrane subfractions from liver and of intact liver tissue with a photolabile bile salt derivative, the sodium salt of (7,7-azo-3 alpha,12 alpha-dihydroxy-5 beta-cholan-24-oyl)-2-aminoethanesulfonic acid, revealed that the hepatobiliary transport of bile salts is accomplished by transport systems different for sinusoidal uptake and canalicular secretion. Polypeptides with apparent Mr values 54,000 and 48,000 interact with bile salts at sinusoidal membrane, whereas a polypeptide with an apparent Mr of 100,000 is involved in bile salt secretion through the canalicular membrane. Photoaffinity labeling with photolabile derivatives of uncharged and cationic compounds provided evidence that the sinusoidal membrane polypeptides exhibit a broad binding specificity. Photoaffinity labeling studies and kinetic studies suggest that hepatic uptake of different amphipathic anions, uncharged compounds and even of cations is mediated by the sinusoidal transport systems which are involved in the uptake of bile salts. Relatively little is known about the specificity of the canalicular bile salt transport system. The fluorescent bile salt derivative, the sodium salt of (N-[7-(4-nitrobenzo-2-oxa-1,3-diazol)]-3 beta-amino-7 alpha, 12 alpha-dihydroxy-5 beta-cholan-24-oyl)-2-aminoethanesulfonic acid, is readily taken up into the hepatocytes of all acinar zones and may be used for the evaluation of the functional state of bile salt transport by fluorescence microscopy. Fluorescent microscopic studies with the fluorescent bile salt derivative showed that ascites hepatoma AS 30D cells do not have the ability to take up bile salts and demonstrated the absence of hepatobiliary bile salt transport in the solid Morris hepatoma 7777. Photoaffinity labeling studies revealed that in both tumor cell models, in hepatoma AS 30D and in Morris hepatoma 7777, the plasma membranes were devoid of the polypeptides having affinities to bile salts and amphipathic cations. A slight labeling of bile salt binding membrane polypeptides in plasma membranes from Morris hepatomas 9618A and TC 5123 opens the possibility to study transport in neoplastic hepatocytes.

Animals↗
PubMed1988

Deletion and insertion mutations in the rpoH gene of Escherichia coli that produce functional sigma 32.

Escherichia coli K-12 strain 285c contains a short deletion mutation in rpoD, the gene encoding the sigma 70 subunit of RNA polymerase. The sigma 70 protein encoded by this allele (rpoD285) unstable, and this instability leads to temperature-sensitive growth. Pseudorevertants of 285c that can grow at high temperature contain mutations in the rpoH gene (encoding the heat shock sigma factor sigma 32), and their mutant sigma 70 proteins have increased stability. We characterized the alterations in three of these rpoH alleles. rpoH111 was a point mutation resulting in a single amino acid substitution. rpoH107 and rpoH113, which are known to be incompatible with rpoD+, altered the restriction map of rpoH. rpoH113 was deleted for 72 base pairs of the rpoH gene yet retained some sigma 32 activity. rpoH107 had two IS1 elements that flanked an unknown DNA segment of more than 6.4 kilobases inserted in the rpoH promoter region. The insertion decreased the amount of rpoH mRNA to less than 0.5% of the wild-type level at 30 degrees C. However, the mRNA from several heat shock promoters was decreased only twofold, suggesting that the strain has a significant amount of sigma 32.

Alleles↗
PubMed1987

Bromobimanes--fluorescent labeling agents for histochemical detection of sulfur containing neuropeptides in semithin sections.

Sulfur containing neuropeptides could be demonstrated in semithin sections of invertebrate nervous tissue, especially of gastropods, by using the bromobimanes as fluorescent labeling agents for thiol groups. Semithin sections showed a brilliant fluorescence of labeled peptides and should be used if an excellent resolution is important. The three bromobimanes (MB: monobromobimane, DB: dibromobimane, MQ: monobromotrimethylammoniobimane) gave positive results under our experimental conditions. Dibromobimane (DB) was selected because the application is more convenient. In gastropods, the bromobimane technique seems to be the most specific and sensitive one compared to the classical neurosecretory staining methods. Neuropeptides with sulfur containing amino acids could be demonstrated in perikarya, axons, and axon swellings easily. We suppose that there are neurons--not stainable by the classical methods--which can be identified as peptidergic ones by the bromobimane technique. A slight reduction of fluorescence intensity (fading) was observed. So, the fading rate was determined for dibromobimane reaction products; a decrease in the fluorescence intensity of 50% was only reached after 1 h using a Neofluar objective 10/0.30. Nevertheless, we suppose that a comparative quantification of the labeled neuropeptides should be possible if special parameters are considered.

Animals↗