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Biomedical subjects

P Sander

Publications and source records attributed to P Sander.

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

[Tazarotene increases the antipsoriatic effect of dithranol in chronic psoriasis].

We examined whether it is possible to increase the antipsoriatic action by combining dithranol with a retinoid (tazarotene). In a randomized, open, prospective study with 50 psoriatic patients (22 females, 28 males, PASI>10) the antipsoriatic effectiveness of dithranol monotherapy to was compared combined therapy with dithranol and retinoid. The combination dithranol/retinoid (collective 2, reduction of the PASI from 17,2 to 2,8) revealed a significantly faster healing than the dithranol monotherapy (collective 1, reduction of the PASI from 18,5 to 4,8). The irritation of the combination therapy as evaluated with clinical score and laser doppler imaging was increased. Anti-psoriatic effectiveness of dithranol can be increased by combining it with tazarotene.

Anthralin↗
PubMed1999

Anal incontinence after obstetric third- /fourth-degree laceration. One-year follow-up after pelvic floor exercises.

The study was a 1-year follow-up of 48 women with obstetric third- /fourth-degree perineal laceration. After primary surgical repair the symptomatic patients were treated with pelvic floor exercises with or without transanal electrical stimulation. Various methods for assessing anal sphincter function were also evaluated. One month postpartum 10 women (21%) complained of anal incontinence, 8 for flatus only; 1 patient was reoperated on. After 1 year none complained of fecal incontinence, and 3 (7%) complained of flatus incontinence. We found relatively few women with anal incontinence after third- /fourth-degree laceration. The pelvic floor training program was effective, but electrical stimulation was abandoned because of anal pain. Grade IIIb lesion, dilution of the sphincter at anal ultrasonography, and sphincter weakness at palpation were significantly related to symptoms of anal incontinence. For routine follow-up after third- /fourth-degree laceration, palpation of the anal sphincter and pelvic floor seems sufficient as first-line assessment.

Adult↗
PubMed1999

A vaginal device (continence guard) in the management of urge incontinence in women.

The aim of the study was to assess the efficacy of a disposable vaginal device in the management of urge incontinence. A total of 38 women with urge incontinence and uninhibited bladder contractions during cystometry were included. They wore the device from morning to night. Before, and again after, using the device for 1 month the women were assessed by pelvic examination, uroflowmetry, postvoid residual urine, two 24-hour pad-tests, a 3-day voiding diary and vaginal and urine cultures. A questionnaire about the subjective effect and adverse events was completed. Thirty women (79%) completed the study. Two (6.7%) were subjectively cured when using the device, 15 (50%) were improved, and 13 (43.3%) experienced unchanged incontinence. The 24-hour pad-test leakage showed a statistically significant decrease (P=0.001) - in 11 women (36.7%) the decrease was more than 50%. The other urodynamic results were unchanged. A significant decrease in the number of daily micturitions was found in the group of responders (P=0.02). No vaginal infections were found; 4 women (13%) had uncomplicated urinary tract infection during the test-period. Subjective complaints were few, and 21 women (70%) wanted to continue the treatment with the device. The vaginal device constitutes a new option in the management of urge incontinence, with a subjective and objective cure/improvement rate of 56.7%. The device is easy to use and well accepted.

Adult↗
PubMed1999

Effect of a vaginal device on quality of life with urinary stress incontinence.

OBJECTIVE: To assess the effect of a vaginal device (Continence Guard) on urine leakage and quality of life. METHODS: Fifty-five women with stress incontinence participated in a 3-month study. They were assessed by the Incontinence Impact Questionnaire, two incontinence-related quality-of-life questions, a generic quality-of-life questionnaire (Short Form-36), two 24-hour home pad weighing tests, a 2-day voiding diary, uroflowmetry, urine cultures, and a questionnaire about subjective effectiveness of the device. RESULTS: Forty-one (74.5%) women completed the study. Estimated on an intent-to-treat basis, the vaginal device was associated with subjective cure in 11 women (20%) and improvement in 27 (49%). The mean 24-hour pad test leakage and leakage episodes in the voiding diary decreased significantly. Fifty-eight percent of the 55 women enrolled wanted to continue using the device after 3 months. The quality of life measured by the Incontinence Impact Questionnaire showed highly significant improvement, and the results of the two incontinence-related quality of life questions also showed significant improvement. Responses to the Short Form-36 general health questionnaire showed no significant changes. Improvement on the Incontinence Impact Questionnaire correlated with improvements in incontinence, whereas the Short Form-36 scores were unchanged. CONCLUSION: Treatment with the Continence Guard significantly decreases leakage and improves quality of life in women with symptoms of urinary stress incontinence. An incontinence-specific, rather than a generic, quality-of-life questionnaire was important in assessing treatment outcomes.

Adult↗
PubMed1999

RecA-Mediated gene conversion and aminoglycoside resistance in strains heterozygous for rRNA.

Clinical resistance to aminoglycosides in general is due to enzymatic drug modification. Mutational alterations of the small ribosomal subunit rRNA have recently been found to mediate acquired resistance in bacterial pathogens in vivo. In this study we investigated the effect of 16S rRNA heterozygosity (wild-type [wt] and mutant [mut] operons at position 1408 [1408wt/1408mut]) on aminoglycoside resistance. Using an integrative vector, we introduced a single copy of a mutated rRNA operon (1408 A-->G) into Mycobacterium smegmatis, which carries two chromosomal wild-type rRNA operons; the resultant transformants exhibited an aminoglycoside-sensitive phenotype. In contrast, introduction of the mutated rRNA operon into an M. smegmatis rrnB knockout strain carrying a single functional chromosomal wild-type rRNA operon resulted in aminoglycoside-resistant transformants. Subsequent analysis by DNA sequencing and RNase protection assays unexpectedly demonstrated a homozygous mutant genotype, rRNAmut/rRNAmut, in the resistant transformants. To investigate whether RecA-mediated gene conversion was responsible for the aminoglycoside-resistant phenotype in the rRNAwt/rRNAmut strains, recA mutant strains were generated by allelic exchange techniques. Transformation of the recA rrnB M. smegmatis mutant strains with an integrative vector expressing a mutated rRNA operon (Escherichia coli position 1408 A-->G) resulted in transformants with an aminoglycoside-sensitive phenotype. Subsequent analysis showed stable heterozygosity at 16S rRNA position 1408 with a single wild-type allele and a single resistant allele. These results demonstrate that rRNA-mediated mutational resistance to aminoglycosides is recessive.

Alleles↗
PubMed1998

The TRP Ca2+ channel assembled in a signaling complex by the PDZ domain protein INAD is phosphorylated through the interaction with protein kinase C (ePKC).

Photoreceptors which use a phospholipase C-mediated signal transduction cascade harbor a signaling complex in which the phospholipase Cbeta (PLCbeta), the light-activated Ca2+ channel TRP, and an eye-specific protein kinase C (ePKC) are clustered by the PDZ domain protein INAD. Here we investigated the function of ePKC by cloning the Calliphora homolog of Drosophila ePKC, by precipitating the TRP signaling complex with anti-ePKC antibodies, and by performing phosphorylation assays in isolated signaling complexes and in intact photoreceptor cells. The deduced amino acid sequence of Calliphora ePKC comprises 685 amino acids (MW = 78 036) and displays 80.4% sequence identity with Drosophila ePKC. Immunoprecipitations with anti-ePKC antibodies led to the coprecipitation of PLCbeta, TRP, INAD and ePKC but not of rhodopsin. Phorbolester- and Ca2+-dependent protein phosphorylation revealed that, apart from the PDZ domain protein INAD, the Ca2+ channel TRP is a substrate of ePKC. TRP becomes phosphorylated in isolated signaling complexes. TRP phosphorylation in intact photoreceptor cells requires the presence of extracellular Ca2+ in micromolar concentrations. It is proposed that ePKC-mediated phosphorylation of TRP is part of a negative feedback loop which regulates Ca2+ influx through the TRP channel.

Amino Acid Sequence↗
PubMed1998

[Mometasone and calcipotriol optimize the initial therapeutic effect of dithranol in chronic persistent psoriasis].

In a randomized study 30 patients with chronic stationary psoriasis were treated with 3 different topical schemes. Group 1 (n = 10) received monotherapy (dithranol (D) twice a day, D/D), group 2 (n = 10) calcipotriol mornings/dithranol evenings (calcipotriol (C)/dithranol (D) C/D) and 3 (mometasone (M) mornings/dithranol (D) evenings, M/D). During the therapy period of 4 weeks we documented the PASI-Score as well as infiltration, erythema and desquamation weekly. The M/D group revealed in the first week a significantly faster reduction of the PASI-score (5.3) than in the D/D group (PASI 13.22). The C/D group (PASI 10.5) show a not significantly faster reduction. After 4 weeks of treatment and after a follow period of 6 weeks there were similar PASI-Scores in all groups. There were less side-effects in the M/D group than in the others. The beginning, more anti-psoriatic effectiveness was achieved by the mometasone/dithranol combination than the other schemes. In the long term, the effects were similar.

Administration, Topical↗
PubMed1998

Investigation of mycobacterial recA function: protein introns in the RecA of pathogenic mycobacteria do not affect competency for homologous recombination.

The recA locus of pathogenic mycobacteria differs from that of non-pathogenic species in that it contains large intervening sequences termed protein introns or inteins that are excised by an unusual protein-splicing reaction. In addition, a high degree of illegitimate recombination has been observed in the pathogenic Mycobacterium tuberculosis complex. Homologous recombination is the main mechanism of integration of exogenous nucleic acids in M. smegmatis, a non-pathogenic mycobacterium species that carries an inteinless RecA and is amenable to genetic manipulations. To investigate the function of recA in mycobacteria, recA- strains of M. smegmatis were generated by allelic exchange techniques. These strains are characterized (i) by increased sensitivity towards DNA-damaging agents [ethylmethylsulphonate (EMS), mitomycin C, UV irradiation] and (ii) by the inability to integrate nucleic acids by homologous recombination. Transformation efficiencies using integrative or replicative vectors were not affected in recA- mutants, indicating that in mycobacteria RecA does not affect plasmid uptake or replication. Complementation of the recA- mutants with the recA from M. tuberculosis restored resistance towards EMS, mitomycin C and UV irradiation. Transformation of the complemented strains with suicide vectors targeting the pyrF gene resulted in numerous allelic exchange mutants. From these data, we conclude that the intein apparently does not interfere with RecA function, i.e. with respect to competency for homologous recombination, the RecAs from pathogenic and non-pathogenic mycobacteria are indistinguishable.

Alleles↗
PubMed1998

A single 16S ribosomal RNA substitution is responsible for resistance to amikacin and other 2-deoxystreptamine aminoglycosides in Mycobacterium abscessus and Mycobacterium chelonae.

Twenty-six clinical isolates of Mycobacterium abscessus resistant to amikacin were identified. Most isolates were from patients with posttympanostomy tube placement otitis media or patients with cystic fibrosis who had received aminoglycoside therapy. Isolates were highly resistant (MICs > 1024 microg/mL) to amikacin, kanamycin, gentamicin, tobramycin, and neomycin (all 2-deoxystreptamine aminoglycosides) but not to streptomycin. Sequencing of their 16S ribosomal (r) RNA revealed that 16 (94%) of 17 had an A-->G mutation at position 1408. In vitro-selected amikacin-resistant mutants of M. abscessus and Mycobacterium chelonae had the same resistance phenotype, and 15 mutants all had the same A-->G substitution at position 1408. Introducing an rRNA operon from Mycobacterium smegmatis with a mutated A-->G at this position into a single functional allelic rRNA mutant of M. smegmatis produced the same aminoglycoside resistance phenotype. These studies demonstrate this 16S rRNA mutation is responsible for amikacin resistance in M. abscessus, which has only one copy of the rRNA operon.

Alleles↗
PubMed1997

The role of ribosomal RNAs in macrolide resistance.

Macrolides are bacteriostatic antibiotics which interfere with the peptidyltransfer function of the ribosome. We have investigated the molecular mechanisms underlying macrolide resistance in Mycobacterium smegmatis, an eubacterium carrying two rRNA operons. Surprisingly, drug resistance was associated not with alterations in ribosomal proteins, but with a single point mutation in the peptidyltransferase region of one of the two 23S RNA genes, i.e. A2058-->G or A2059-->G. This mutation resulted in a heterozygous organism with a mutated and a wild-type rRNA operon respectively. Reverse transcriptase sequencing indicated the expression of both wild-type and mutated rRNAs. The mutated operon was introduced into genetically engineered rrn- strains of M. smegmatis carrying a single functional rRNA operon and into parental M. smegmatis with two chromosomal rRNA operons, using gene transfer as well as gene replacement techniques. The results obtained demonstrate the dominant nature of resistance. As exemplified in our results on macrolide resistance, a complete set of genetic tools is now available, which allows questions of dominance vs. recessivity and gene dosage effects in eubacterial ribosomal nucleic acids to be addressed experimentally in vivo.

Alleles↗
PubMed1996

The transient receptor potential protein (Trp), a putative store-operated Ca2+ channel essential for phosphoinositide-mediated photoreception, forms a signaling complex with NorpA, InaC and InaD.

The transient receptor potential protein (Trp) is a putative capacitative Ca2+ entry channel present in fly photoreceptors, which use the inositol 1,4,5-trisphosphate (InsP3) signaling pathway for phototransduction. By immunoprecipitation studies, we find that Trp is associated into a multiprotein complex with the norpA-encoded phospholipase C, an eye-specific protein kinase C (InaC) and with the InaD protein (InaD). InaD is a putative substrate of InaC and contains two PDZ repeats, putative protein-protein interaction domains. These proteins are present in the photoreceptor membrane at about equimolar ratios. The Trp homolog analyzed here is isolated together with NorpA, InaC and InaD from blowfly (Calliphora) photoreceptors. Compared to Drosophila Trp, the Calliphora Trp homolog displays 77% amino acid identity. The highest sequence conservation is found in the region that contains the putative transmembrane domains S1-S6 (91% amino acid identity). As investigated by immunogold labeling with specific antibodies directed against Trp and InaD, the Trp signaling complex is located in the microvillar membranes of the photoreceptor cells. The spatial distribution of the signaling complex argues against a direct conformational coupling of Trp to an InsP3 receptor supposed to be present in the membrane of internal photoreceptor Ca2+ stores. It is suggested that the organization of signal transducing proteins into a multiprotein complex provides the structural basis for an efficient and fast activation and regulation of Ca2+ entry through the Trp channel.

Amino Acid Sequence↗
PubMed1996

[The open, interdisciplinary incontinence clinic at Hvidovre Hospital. Preliminary experiences from the first 16 months].

A "minimal care" program for examination and treatment of urinary incontinence in an open access incontinence clinic was assessed. The first 300 women and 27 men consecutively investigated in the clinic are described. A reference program based on minimal relevant work-up and non-operative treatment as first line with use of minimal resources was followed. Of 171 evaluated women, 100 received non-operative treatment besides general advice on voiding/toilet pattern and appropriate incontinence appliances. Subjectively 69% felt cured or very much improved, 25% experienced improvement while 6% did not report benefit of the treatment. Objectively, diminished leakage was demonstrated by pad-weighing test. Similar results were found in the treated men. Our preliminary results demonstrate, that an open access, interdisciplinary clinic is patient-accepted and effective for the evaluation and treatment of urinary incontinence.

Adolescent↗
PubMed1996

Phosphorylation of the InaD gene product, a photoreceptor membrane protein required for recovery of visual excitation.

In an approach directed to isolate and characterize key proteins of the transduction cascade in photoreceptors using the phosphoinositide signaling pathway, we have isolated the Calliphora homolog of the Drosophila InaD gene product, which in Drosophila InaD mutants causes slow deactivation of the light response. By screening a retinal cDNA library with antibodies directed against photoreceptor membrane proteins, we have isolated a cDNA coding for an amino acid sequence of 665 residues (Mr = 73,349). The sequence displays 65.3% identity (77.3% similarity) with the Drosophila InaD gene product. Probing Western blots with monospecific antibodies directed against peptides comprising amino acids 272-542 (anti-InaD-(272-542)) or amino acids 643-655 (anti-InaD-(643-655)) of the InaD gene product revealed that the Calliphora InaD protein is specifically associated with the signal-transducing rhabdomeral photoreceptor membrane from which it can be extracted by high salt buffer containing 1.5 M NaCl. As five out of eight consensus sequences for protein kinase C phosphorylation reside within stretches of 10-16 amino acids that are identical in the Drosophila and Calliphora InaD protein, the InaD gene product is likely to be a target of protein kinase C. Phosphorylation studies with isolated rhabdomeral photoreceptor membranes followed by InaD immunoprecipitation revealed that the InaD protein is a phosphoprotein. In vitro phosphorylation is, at least to some extent, Ca 2+ dependent and activated by phorbol 12-myristate 13-acetate. The inaC-encoded eye-specific form of a protein kinase C (eye-PKC) is co-precipitated by antibodies specific for the InaD protein from detergent extracts of rhabdomeral photoreceptor membranes, suggesting that the InaD protein and eye-PKC are interacting in these membranes. Co-precipitating with the InaD protein and eye-PKC are two other key components of the transduction pathway, namely the trp protein, which is proposed to form a Ca2+ channel, and the norpA-encoded phospholipase C, the primary target enzyme of the transduction pathway. It is proposed that the rise of the intracellular Ca2+ concentration upon visual excitation initiates the phosphorylation of the InaD protein by eye-PKC and thereby modulates its function in the control of the light response.

Amino Acid Sequence↗
PubMed1996

Isolation of genes encoding photoreceptor-specific proteins by immunoscreening with antibodies directed against purified blowfly rhabdoms.

The proteins which perform and regulate key steps in phototransduction are assumed to be localized in the rhabdomeric membrane of invertebrate photoreceptor cells. We have employed antibodies raised against rhabdoms purified from blowfly eyes in order to isolate copy deoxyribonucleic acid (cDNA) clones encoding proteins that are required in the phototransduction machinery. By immunoscreening a Calliphora retinal cDNA library, we obtained clones of genes coding for five different proteins. As revealed by partial cDNA sequence analysis, three of these genes represent the Calliphora homologs of Drosophila trp, inaC and InaD, while the other two displayed no homology to known genes. Northern blot analysis confirmed that trp, inaC and InaD transcripts were present in RNA isolated from the retina, but not in RNA isolated from brain or thorax. Specific antibodies directed against trp, inaC and InaD protein were raised using recombinantly expressed proteins or synthetic peptides. Western blot analyses revealed that trp, inaC and InaD protein are specifically associated with the rhabdomeral photoreceptor membrane. Extraction of membranes with buffers of different ionic strengths suggested that the trp gene product is an integral membrane protein, whilst the inaC and InaD gene products are peripherally bound membrane proteins. This demonstrates that the immunoscreening approach used here can be successfully applied to isolate genes that code for either integral or peripheral photoreceptor membrane proteins.

Amino Acid Sequence↗
PubMed1996

Introducing mutations into a chromosomal rRNA gene using a genetically modified eubacterial host with a single rRNA operon.

Gene-inactivation techniques were employed to construct a eubacterial organism harbouring a single functional rRNA operon. This mutant of Mycobacterium smegmatis permits replacement of the single remaining rRNA operon with a homologous fragment from a vector-borne gene. By homologous recombination with the chromosome a plasmid-borne rDNA segment with resistance markers substitutes for the corresponding region of the chromosomal rRNA operon, resulting in a homogeneous population of mutated ribosomes in the cell. As a first result we demonstrate that the single allelic knock-out strain allows for isolation of rRNA mutants with a drug-resistant phenotype, circumventing the problem of recessivity which prohibits the isolation of such mutants in organisms with multiple rRNA operons. Subsequently, by allelic exchange experiments, it was demonstrated that the rRNA mutation found indeed confers drug resistance in vivo. This system provides intriguing potential for the study of the structure and function of ribosomal RNAs.

Alleles↗
PubMed1996

Molecular mechanisms of clarithromycin resistance in Mycobacterium avium: observation of multiple 23S rDNA mutations in a clonal population.

The peptidyltransferase region of the 23S rRNA gene (the probable target site for the macrolides) was investigated in blood isolates of Mycobacterium avium recovered from 38 patients before and after the development of clarithromycin resistance. Point mutations were identified in 100% of the 74 resistant relapse blood isolates but in none of 69 susceptible pretreatment isolates. Multiple mutations were identified in isolates from 23 (61%) of 38 patients. Of the 63 identified mutations, 95% involved adenine at bp 2058. Single-colony clones from cultures that were mixtures of more than one mutation revealed a single mutation within each clone. Pulsed field gel electrophoresis of genomic DNA restriction fragments revealed that 13 (81%) of 16 multiple mutations identified in the same patient were derived from a single infecting strain. In vitro investigation revealed the same point mutations observed in vivo. This study defines the probable mechanism of clarithromycin resistance in M. avium and provides in vivo evidence that mutational resistance is random and selection-directed.

Base Sequence↗