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Biomedical subjects

A Hahn

Publications and source records attributed to A Hahn.

At least 19 recordsLinked to original sources
PubMed1992

Coordinate genetic control of yeast fatty acid synthase genes FAS1 and FAS2 by an upstream activation site common to genes involved in membrane lipid biosynthesis.

A systematic search for upstream controlling elements necessary for efficient expression of the yeast fatty acid synthase genes FAS1 and FAS2 revealed identical activation sites, UASFAS, in front of both FAS genes. The individual element confers, in a heterologous yeast test system, an approximately 40-fold stimulation of basal gene expression. The UASFAS motifs identified have the consensus sequence TYTTCACATGY and function in either orientation. The same sequence motif is found in the upstream regions of all so far characterized yeast genes encoding enzymes of phospholipid biosynthesis. In gel retardation assays, a protein factor, Fbf1 (FAS binding factor), was identified which interacted with UASFAS. The UASFAS motif proved to be an inositol/choline responsive element (ICRE) conferring strict repression by exogenous inositol and choline on a heterologous reporter gene. Its core sequence perfectly matches the CANNTG motif typical of basic helix-loop-helix DNA-binding proteins. In contrast to the individual UASFAS element, the intact yeast FAS promoters are not significantly influenced by inositol and choline, and thus allow nearly constitutive fatty acid synthase production. Available evidence suggests that additional cis- and trans-acting elements, other than UASFAS and Fbf1, are involved in this constitutive FAS gene expression.

Base Sequence↗
PubMed1992

High-performance liquid chromatographic determination of biotin in biological materials after crown ether-catalyzed fluorescence derivatization with panacyl bromide.

This paper reports a high-performance liquid chromatographic (HPLC) technique to determine biotin in biological samples. Biotin and the internal standard dethiobiotin are converted into fluorescent derivatives by using panacyl bromide [p-(9-anthroyloxy)phenacyl bromide] as a fluorescence label. Biotin is extracted from biological tissue with trichloroacetic acid and the extract is purified by a combination of solid-phase extraction on C18 cartridges, ion-exchange chromatography on DOWEX formate resin, and thin-layer chromatography. The purified sample extract is derivatized in the presence of a crown ether. The resulting panacyl esters can be separated on reversed-phase as well as on normal-phase HPLC. Normal phase HPLC is preferable because it provides higher sensitivity and demands less sample pretreatment. Analysis of rat intestinal tissue revealed that only about 13% of the biotin is present in free form whereas 87% is bound in proteins from which it can be released by hydrolysis. Biotin values determined by this method are comparable to those obtained by other techniques.

Acetophenones↗
PubMed1992

Identification of a new DMD gene deletion by ectopic transcript analysis.

The detailed genetic analysis of the Duchenne/Becker muscular dystrophy gene is hindered by the large number of exons involved and their separation by huge introns. These problems can be overcome by the analysis of mRNA rather than genomic DNA and ectopic transcripts derived from peripheral blood lymphocytes provide a convenient source of material. Using reverse transcription and nested PCR, we show here a comprehensive strategy for the rapid and complete analysis of the coding sequences from complex genes and illustrate its potential by the identification of a hitherto undescribed single exon deletion.

Base Sequence↗
PubMed1992

Hereditary sensory radicular neuropathy: defective neurogenic inflammation.

Hereditary sensory radicular neuropathy exhibits autosomal dominant inheritance with complete penetrance in males and incomplete penetrance in females. Newer tests of small sensory nerve function were used in screening 8 family members aged between 14 and 66 years. All exhibited some frequent features of the disorder with an onset in the 2nd or 3rd decade, foot ulceration, foot callus, loss of pin prick, thermal and light touch sensation, and some reduction in vibration acuity and proprioception in the lower limbs. The hands were involved in 3 of 8, muscle involvement was present in 5 of 8, but deafness was not detected by audiometry. Nerve conduction velocity, sensory action potentials, latency and amplitude, thermal acuity, vibration acuity and axon reflex flares were measured in all patients. One sural nerve biopsy confirmed the presence of peripheral fibre loss in this predominantly sensory neuropathy. Chemically evoked axon reflex tests were used to evaluate the extent of primary sensory nerve fibre involvement. All patients were tested using a Moor MBF 3-D dual channel laser Doppler velocimeter. Acetylcholine or phenylephrine iontophoretically applied as 16 mC doses evoked absent or tiny axon reflexes in areas of impaired pin prick sensation. By contrast, direct microvascular dilator responses to nitroprusside (smooth muscle dependent) and acetylcholine (endothelium-dependent) were present but somewhat reduced in areas with defective neurogenic inflammation. These results differ significantly from the responses obtained in age-matched healthy controls (P < 0.05). Foot pressure analysis was performed for orthoses in 2 affected members with foot ulceration using the Musgrave Footprint system.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Optimized high-performance liquid chromatographic procedure for the separation and determination of the main folacins and some derivatives. II. Extraction method and application to rat liver.

Different methods for the extraction of folacins from biological materials and the hydrolysis of pteroylpolyglutamates prior to high-performance liquid chromatography were investigated. Acetone precipitation of proteins led to higher extraction rates of folates from biological materials as examined by using an endogenous labelling technique. It also caused less destruction of some folates but could not be combined with subsequent hydrolysis of pteroylpolyglutamates. Pteroylpolyglutamates were hydrolysed by a partially purified suspension of pteroylpolyglutamates hydrolase (PPH). Comparative studies on the folate content of rat liver revealed that complete hydrolysis of polyglutamates could also be achieved by incubating the homogenized tissue at 37 degrees C to allow endogenous PPH to act. This procedure causes interconversions of folates and is therefore not suitable for the analysis of biological materials.

Animals↗
PubMed1991

Transport of pteroylglutamic acid into brush border membrane vesicles from rat small intestine is a partially carrier-mediated process.

Intestinal transport of PteGlu was studied using BBMV from rat small intestine. Transport was neither coupled to a specific cation gradient nor was it influenced by variations of the membrane potential. In the presence of a transmembrane pH gradient (pHout less than pHin) initial transport was significantly higher compared to studies without pH gradient. Under these conditions transport could be inhibited by pretreating the vesicles with DIDS, an inhibitor of anion exchange systems. Uptake of PteGlu could not be enhanced by preloading the BBMV with HOP4(2-) and Cl- and was not sensitive to DIDS under these conditions. Uptake studies using different concentrations of PteGlu revealed dual transport kinetics in the presence of a pH gradient and linear uptake in its absence. It could be concluded that uptake is mediated by a PteGlu-/OH(-)-antiporter at low substrate concentrations and occurs by non-ionic diffusion at higher concentrations or in the absence of a pH gradient. In an additional series of experiments it could be shown that about one-third of the substrate is bound to the membrane and is not transported. The biological significance of this binding remains unclear.

Animals↗
PubMed1991

Epilation of upper lip hirsutism with a eutectic mixture of lidocaine and prilocaine used as a topical anesthetic.

Twenty-one patients were included in a double-blind, placebo-controlled, cross-over study with a eutectic mixture of lidocaine and prilocaine (EMLA). EMLA or placebo was placed on the upper lip for 1 hour; diathermy was then performed for 10 minutes. The pain caused by diathermy was evaluated by the patients and the cosmetologist on a four-point scale. The results of the investigation showed that there was significantly less pain after application of 5 gm of EMLA cream on the upper lip than after application of placebo, assessed both by the patient and by the cosmetologist. Eighteen of 20 patients preferred EMLA (p less than 0.0001). Local reactions were few and mild.

Adult↗
PubMed1991

Cranio-corpo-graphy. A neurootological screening test.

Cranio-corpo-graphy affords a photographic representation of the patient's "radar-like" movement patterns as he performs the standing (Unterberger, Fukuda) and stepping (Romberg) tests. Of the various parameters used for analysis, a wide angular deviation, i.e., where the patient deflects more than circa 60 degrees away from the sagittal axis, is taken to signify a peripheral dysfunction, usually involving the side of deviation. In addition, broad lateral sway values and standing tests sways suggest a central pathology. In this study, three data banks were created. One consisting of 500 patients tested in our department over the last ten years, all showing a normal cranio-corpo-graphic pattern; the second made up of 500 patients showing a clear peripheral pattern, i.e., abnormal angular deviation with normal sway values and the third (650 patients) with a typical central disturbance, i.e. a broad lateral sway. These groups were then submitted to a detailed statistical analysis.

Adult↗
PubMed1990

[Cryosurgical treatment of precancerous cheilitis abrasiva].

Between 1984 and 1988, 44 patients suffering from cheilitis abrasiva praecancerosa were treated with cryosurgery using a nitrous oxide cryoprobe. A single treatment proved sufficient in 35 patients (80%). 9 patients (20%) developed a recurrent lesion 4 to 28 months after cryosurgery. All recurrences appeared within the first year. On account of the recidivity of the disease, we recommend a careful follow-up of the patients. On the other hand, cryosurgery has the advantage that it can be applied in elderly persons as well as in patients with concomitant internal diseases. In pracancerous lesions, the common drawbacks of a surgical therapy such as diminution of the lower lip and impairment of the superficial sensitivity can be avoided with the help of this technique. Invasive carcinomas of the lower lip, however, should not be treated with cryosurgery.

Aged↗
PubMed1990

Self-injury in psychiatric in-patients.

Suicide and self-injury in-patients were identified on the basis of a retrospective content analysis of special incidence reports completed the preceding year at an urban state psychiatric hospital. Select clinical and biodemographic variables were then examined, and in order to determine the importance of these variables in the prediction of incident severity, a multiple regression analysis was performed. Schizophrenic patients were found to be significantly over-represented among both the self-injury and suicide patients.

California↗
PubMed1990

[New aspects of diagnostic criteria in BERA tests].

The purpose of the presented work was to investigate the relationship between the length of I-III and I-V intervals during BERA examinations on the intensity of the stimulus in healthy subjects. Furthermore to assess the normal range of the maximum length of I-III and I-V intervals. Twenty-seven subjects aged 15-57 years, incl. 10 men, were examined. The stimuli were 100 us clicks, the repeating rate was 30/s, the stimulation intensity 0-85 dB nHL. The examination was made after administration of diazepam or rohypnol. TDH 49 earphones were used. Into the external auditory meatus on the examined side an electrode of the authors' own design in the shape of an open tube was introduced. The length of I-III and I-V intervals depended on the intensity of stimulation. The differences of mean values of the length intervals at stimulation intensities of 65 dB nHL and 45 dB nHL were statistically significant: p less than 0.02 for interval I-III and p less than 0.0001 for interval I-V. We take as the upper borderline of the normal length of intervals I-III approximately 2.8 ms and of intervals I-V 4.7 ms, if the latency of wave I is smaller than 2.5 ms. When the latency of wave I is greater, even longer I-III and I-V intervals may be still normal.

Acoustic Stimulation↗
PubMed1989

[Dusodril in the ambulatory care of inner ear disorders].

The author discusses causes of disorders of the internal ear. He describes the tactics of treatment used in his department and gives an account of the therapeutic effect of the drug. In the subsequent parts of the paper results are quoted which were achieved during treatment of a total of 82 ambulatory patients. Dusodril is comparable with other preparations used in disorders of the internal ear. According to the author's observation it influences the symptomatology of the internal ear in the following order: dizziness hypacusia, tinnitus.

Adolescent↗
PubMed1989

[Comprehensive diagnosis of tumors of the statoacoustic nerve].

The authors describe first the diagnosis procedure in tumours of the statoacoustic nerve, and analyze the reasons of their late detection. In the submitted paper they analyze in detail the applied examination methods. Consistent with data in the literature, they state that the greatest contribution to diagnosis is that of objective audiometry computed tomography has the final word in diagnosis; the authors proved by CT in a group of 37 examined patients in 21 a neurinoma of the statoacoustic nerve or another expansive lesion of the posterior cranial fossa.

Audiometry↗
PubMed1988

Immunohistochemistry (S 100, KL 1) and human papillomavirus DNA hybridization on morbus Bowen and bowenoid papulosis.

In this study 55 paraffin embedded samples defined as Bowen's disease or bowenoid papulosis were investigated with antibodies against S 100 protein and keratins (KL 1). S 100-positive cells were quantified and related to defined section area of the epidermal compartment by computer-assisted image analysis. The density of S 100-positive cells was compared with normal skin and was particularly related to growth patterns and keratinization of the different lesions under study. S 100-positive dendritic cells were found to be reduced overall in bowenoid lesions when compared with normal skin. Lesions with high counts of S 100-positive dendritic cells most frequently showed a solitary growth pattern with highly conserved architecture and differentiation and no tendency to stromal invasion. In contrast, cases with low counts of S 100-positive cells very often showed multifocal development, a high degree of architectural disturbance and dedifferentiation. In this group, stromal invasion (cases of invasive carcinoma associated with Bowen's disease) was seen more often. Interestingly, this latter group of cases also revealed a peculiar keratin pattern. Frequently, the basal cell layer was decorated with KL 1 antibody, which usually recognizes only suprabasaly located keratinocytes. No differences between Bowen's disease and bowenoid papulosis were found in terms of densities of S 100-positive dendritic cells and keratin pattern. In our experience, extragenital Bowen's disease and genital Bowen's disease can not be distinguished on purely morphological grounds or with the immunocytochemical approach presented here. Interestingly, when employing in situ hybridization with HPV 16 probes three of seven samples of genital Bowen's disease harboured HPV 16 DNA, whereas six cases of extragenital disease were negative.

Adult↗