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Biomedical subjects

R Marquardt

Publications and source records attributed to R Marquardt.

At least 19 recordsLinked to original sources
PubMed1991

Increased yield of a lysozyme after self-cloning of the gene in Streptomyces coelicolor "Müller".

Streptomyces coelicolor "Müller" DSM3030 excretes a lysozyme comprising both beta-1,4-N-acetyl- and beta-1,4-N,6-O-diacetyl muramidase activities. The lysozyme is named Cellosyl. Gene libraries have been established using genomic DNA from the wild-type strain, S. coelicolor DSM3030, and from an overproducing mutant, S. coelicolor HP1, which exhibits about a twofold increase in lysozyme production. The lysozyme-encoding genes (cel) from both strains were detected by oligodeoxynucleotide hybridization. The nucleotide sequence of the cel genes isolated from both strains was shown to be identical. The different levels of lysozyme production could not be correlated with any mutations at the cel gene locus. The cel gene isolated from the wild-type strain could not be expressed in some other species of Streptomyces. However, self-cloning of the cel gene into S. coelicolor DSM3030 and HP1 resulted in a 2.5-fold increase in lysozyme production.

Amino Acid Sequence↗
PubMed1991

Molecular cloning and characterization of the recA gene of Methylomonas clara and construction of recA deficient mutant.

The recA gene of the methylotrophic bacterium Methylomonas clara has been isolated from a genomic library by hybridization with the Escherichia coli recA gene. Its complete nucleotide sequence consists of 1029 bp encoding a polypeptide of 342 amino acids. Nucleotide sequence analysis of the M. clara recA gene revealed extensive homologies to recA genes from E. coli and Pseudomonas aeruginosa. Part of the physiological activity of the M. clara RecA protein has become evident in that E. coli recA mutant HB101 is complemented. The cloned recA gene has been modified in vitro by site-specific mutagenesis and by insertion of a kanamycin-resistance gene cassette into the recA coding sequence. M. clara recA mutants were obtained by replacement of the active recA gene by an in-vitro inactivated gene copy.

Amino Acid Sequence↗
PubMed1991

[Modification of tear film break-up time by beta blocker eyedrops without preservatives].

Traditional beta-blocking eye drops preserved with benzalkonium chloride show an adverse effect on the precorneal tear film, which can be measured by checking the break-up-time (BUT). To decide, whether this adverse effect is caused more by the beta-blocking drug or the preservative, we tested the influence of timolol eye drops without preservative in single dose units Timosine) on the BUT in a prospective, open study. These eyedrops caused no significant shortening of the BUT in persons, which where untreated before. Patients using preserved beta-blocking eye drops and having irritations of their eyes showed significant prolongation of the BUT after changing the therapy to Timosine. Preservative-free beta-blocking eye drops are a real improvement in the therapy of glaucoma patients with irritated eyes.

Glaucoma↗
PubMed1991

Mutations in the HML E silencer of Saccharomyces cerevisiae yield metastable inheritance of transcriptional repression.

Mating-type genes resident in the silent cassette HML at the left arm of chromosome III are repressed by the action of four SIR gene products, mediated independently through two cis-acting sites, termed the E and I silencers. We have found that in the absence of the I silencer, deletion of any one of three distinct elements within E yields partial derepression of the mating-type genes resident at HML, whereas deletion of any two yields full derepression. These elements correspond to a binding site for the abundant DNA-binding protein RAP1, an autonomous replicating sequence (ARS), and an as yet undistinguished region. From detailed deletion analysis of the E site we conclude that the ARS element contributes to silencer function in a capacity distinct from its role as an initiator of DNA replication. In addition, we find that strains deleted for any one of these elements comprise two genetically identical but phenotypically distinct types of cells: Those with HML apparently fully derepressed, and those with HML apparently completely repressed. These results reinforce the notion that epigenetic inheritance is an intrinsic characteristic of silencer action.

Chromosomes, Fungal↗
PubMed1990

[Chronic conjunctivitis].

The etiology, clinical picture, diagnosis and treatment of chronic inflammatory diseases of the conjunctiva are described. It is emphasized that, despite the respective specific etiology, the symptomatology has common factors, treatment is difficult and all too often only symptomatic, and chronic inflammatory diseases of the conjunctiva sooner or later lead to the so-called dry eye syndrome.

Acute Disease↗
PubMed1989

Ocular perfusion pressures in different types of glaucoma.

It is widely accepted that a disturbed blood supply of the optic disc may cause (in addition with an increased intraocular pressure) optic nerve fibre damage. Therefore we measured ocular perfusion pressures in 79 healthy subjects. In 18 patients with low tension glaucoma, in 27 patients suffering from ocular hypertension and in 49 glaucoma (OAG) patients. For measuring perfusion pressures we used the technique of oculo-oscillo-dynamography (OODG) as described by Ulrich. Additionally we measured intraocular pressure and systemic blood pressure. In OODG the IOP is simultaneously increased in both eyes by application of a suction cup. After increase of the IOP the negative pressure in the suction cup is slowly and linearly decreased. During this decrease the pulse-depending oscillations of each eye are recorded on a strip-chart-recorder. By means of this method retinal and ciliary perfusion pressures can be separated. As a result we could show that mean arterial blood pressure and systolic retinal perfusion pressure were comparable and not statistically significantly different between the groups examined. The systolic ocular perfusion pressures in patients with low tension glaucoma showed a highly statistically significant reduction compared with the other groups. Between healthy subjects, OAG-patients and patients suffering from ocular hypertension there was no difference in systolic ciliary perfusion pressure detectable.

Aged↗
PubMed1989

Determination and in vivo characterization of the basic replicon of natural plasmids of Methylomonas clara.

The basic replicon of the endogenous Methylomonas clara plasmid pBE-2 and its derivatives was defined to a region of 2.7 kb by in vivo deletions and conjugative transfer experiments using Escherichia coli-M. clara hybrid plasmids. Origin activity was found to be confined to a maximal length of 1.3 kb. The origin consists of two fragments which can be separated more than 4 kb by the integration of foreign DNA fragments without loss of function. A fragment having a maximum size of 2.1 kb supports in trans replication initiation at the origin. In addition, two incompatibility determinants were revealed, one localized in the origin fragment and the other outside the origin. Incompatibility between two basic replicons of the natural M. clara plasmids can be overcome by the integration of one of them in the compatible IncP plasmid R68-Kms. No homology was found between the plasmid basic replicon and the chromosomal DNA of M. clara.

Chromosome Deletion↗
PubMed1989

[Clinical experiences with a therapeutic collagen contact lens].

In 43 eyes of 40 patients, the therapeutic effects of a self-dissolving hydrophilic collagen contact lens were investigated. Epithelial defects of any source, lamellar perforating corneal injuries, and trophic sterile corneal ulcers were defined as indications for the use of the lens. Collagen contact lenses were applied with biodegradation times of 6, 24, and 72 h. All patients tolerated the lens well, and no adverse reactions to the collagen material were observed. In all diseases where the lens was applied, re-epithelialization was found to be relatively fast.

Collagen↗
PubMed1988

[Perforating eye injuries caused by darts].

Four perforating eye injuries sustained by children playing with darts are analyzed. The injuries occurred within a period of 17 months. All the patients had minor injuries of the anterior segment and severe injuries in the posterior segment, such as vitreous hemorrhages and double perforations. Precautions should be taken to prevent such injuries: games involving darts are not suitable for children.

Adolescent↗
PubMed1988

[Clinical experiences with a therapeutic collagen contact lens. Initial results].

Clinical treatment with a self-dissolving collagen bandage lens was studied in 29 eyes. The lens was used in ten eyes with corneal abrasion, seven with lamellar perforating corneal injuries, six with corneal abrasion following foreign body removal, two after pterygium surgery, in one corneal abrasion caused by radiation, in two eyes with photoelectric keratoconjunctivitis, and in one patient with a trophic-sterile corneal ulcer. In all cases wearing comfort was excellent and no allergic reactions were observed. The patients with corneal abrasions experienced a significant reduction in pain immediately after application of the lens, so that no pressure patch was necessary. In the cases with corneal abrasion due to radiation and trophic-sterile ulcer, re-epithelialization occurred more rapidly than with the customary treatment.

Adolescent↗
PubMed1988

[Ocular hemodynamics following suction cup oculopression].

In the study reported here the authors investigated the influence on ocular perfusion pressures of suction-cup oculopression, a procedure which permits oculopression without orbital compression. Patients over 50 years of age were examined before cataract extraction. Ulrich's method of ocular oscillodynamography was used to determine ocular perfusion pressures. A Mikuni and Yoneyama suction-cup dynamometer was applied for suction-cup oculopression. Ocular hypotonia following suction-cup oculopression was adequate and comparable to that achieved by other oculopression methods. After oculopression a significant increase in ocular perfusion pressures (retinal, ciliary, and diastolic) was found. However, ocular blood pressure remains constant after oculopression. Moreover, the increase in ocular perfusion pressure could not be explained by oculocardiac reflexes, because there was no change in systemic arterial blood pressure. It must be assumed, therefore, that the increase in ocular perfusion pressures is caused by a lowering of resistance, i.e., a drop in intraocular pressure.

Blood Pressure↗
PubMed1988

[Ocular hemodynamics following local administration of clonidine].

The influence of topically applied clonidine 0.125% on ocular hemodynamics was investigated in ten patients with open-angle glaucoma and ten healthy volunteers, using a new, differentiated method. Ocular perfusion pressures were determined by Ulrich's method of oculo-oscillodynamography. Following monocular application of clonidine 0.125% eye drops a clear decrease in systemic blood pressure and a somewhat less pronounced reduction of ocular perfusion pressure was observed in both groups of patients. The reduction in ocular perfusion pressures was higher in the eye after drop application than in the untreated control eye. It must therefore be assumed that clonidine 0.125% eye drops have a local perfusion pressure-reducing effect in addition to their systemic effect.

Adult↗
PubMed1987

[Gelatinous tear substitutes and nonspecific eye ointments in the critical care unit and in perioperative use].

The effect of Vidisic (a new jelly artificial tear solution) and an ointment basing on Dexpanthenol on the tear production and the tear film stability was studied both on patients in the intensive care units (ICU) and during operations. In 10 relaxed and ventilated patients of the ICU there was no significant change in the tear production after application of either therapy. In 30 patients, undergoing surgery in endotracheal anaesthesia, the break-up-time and the test according to Schirmer were measured pre- and postoperatively. Like in the ICU-patients no difference in tear production could be found. Regarding the stability of the precorneal tear film however Vidisic was more effective than ointment basing on Dexpanthenol. Especially this clear jelly artificial tear solution allowed in contrast to the ointment a permanent and reliable judgement of the pupillary reaction. In addition the patients felt more comfortable with Vidisic.

Acrylates↗
PubMed1986

[Treatment of dry eye with a new gel in eyedrop form].

Vidisic, a liquid gel derived from a polymerisate of acrylic acid for the treatment of dry eyes, was tested for 3 months in an open prospective study in 55 patients with severe dry eye. Vidisic spreads well over the cornea and conjunctiva and does not cause streaks. Compared with other tear substitutes so far available, Vidisic has a much longer viability, so that no more than 3 or 4 drops a day are necessary. Also, Vidisic is better tolerated and more effective. Moreover, there was a significant improvement, both subjectively and objectively, in the patients' conditions.

Acrylates↗