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Biomedical subjects

R Mayer

Publications and source records attributed to R Mayer.

At least 109 records · Page 6Linked to original sources
PubMed1994

Correlations between dynamic urethral profilometry and perivaginal pelvic muscle activity.

Of 208 ambulatory female subjects evaluated for complaints of urinary incontinence, complete history, physical findings, and urodynamic data were available on 163 patients allowing correlation of measures of perivaginal muscle activity to urethral profilometry measurement of sphincter strength. Perivaginal measures include pelvic digital exam score as well as vaginal electromyography with a modified perinometer. Urethral profilometry was performed at rest and during pelvic muscle contractions in both supine and standing positions. There was a moderate and significant correlation (r = 0.19 to 0.32) between profilometry measures of voluntary sphincter contractions and perivaginal EMG parameters of endurance peak and area, as well as to the digital test parameters of pressure and displacement. The correlation values between the vaginal EMG and the Digital Test scale of perivaginal strength were higher (r = 0.28 to 0.74). When the patients with pure stress incontinence were stratified by degrees of incontinence (mild, moderate, severe), urethral prolfilometry measures were a more accurate indicator of severity of incontinence than measures of perivaginal strength or the degree of bladder neck mobility as measured by the Q-tip test.

Adult↗
PubMed1994

New substrates of papain, based on the conserved sequence of natural inhibitors of the cystatin family.

A series of peptide substrates with different fluorogenic leaving groups has been synthesized. The peptide moiety in these substrates mimics a highly conserved sequence (QVVAG) in the natural reversible inhibitors of cysteine proteinases, the cystatins, that participates to the tight binding of target proteinases. This sequence is invariably cleaved at the A-G bond when synthetic peptides containing it were incubated with papain. AEC and AMC fluorophores were therefore attached to the Ala residue to construct new substrates for cysteine proteinases. The solubility of the resulting substrates was improved by attaching a N-terminal gluconoyl group, or by introducing an arginyl residue at P5 (nomenclature of Schechter I, Berger A (1967) Biochem Biophys Res Commun 27, 157-162). Neither induced significant changes in the kcat/Km values with papain. Those values were all in the 10(5) M-1 s-1 range. The kcat/Km was increased 10-50-fold by using substrates with intramolecularly quenched fluorescence. With these, the enzyme specificity on both sides of the scissile bond can be investigated. The substrate Abz-QVVAGA-EDDnp is among the most sensitive papain substrates ever reported, with a kcat/Km value of 29 10(6) M-1 s-1. The positioning and conformation of the bound QVVA moiety within the active site of papain were predicted by molecular modelling using the X-ray coordinates of a peptide inhibitor-papain complex.

Amino Acid Sequence↗
PubMed1994

Dye-hydrophobic hapten conjugate/anti-dye antibody complex as immunogen: preparation of hydrophobic hapten-specific monoclonal antibodies.

In order to induce the production of antibodies specific for small molecules, it is common to link them to a protein. However, when the small molecule is very hydrophobic it is extremely difficult to prepare such a conjugate. Here, we describe a simple way to obtain an antigenic conjugate under controlled conditions: in a first step a very hydrophobic hapten, cholanic acid, is linked to a dye, basilen blue, in organic solvent; in a second step the cholanic acid-basilen blue conjugate is dissolved in phosphate buffered saline and mixed with rabbit polyclonal anti-basilen blue antibodies previously raised in rabbits against basilen blue-key-hole limpet hemocyanin conjugate. Such a complex, which dissociates very slowly, appears to be a good immunogen in mice. Anti-cholanyl residue monoclonal antibodies were produced and characterized.

Animals↗
PubMed1994

Damage to murine kidney and intestine from exposure to the fields of a piezoelectric lithotripter.

Earlier studies, in which murine kidneys were exposed to spherically diverging, spark-generated shock waves, demonstrated extensive hemorrhage in the interior of the organ at peak positive pressures somewhat less than 10 MPa. With comparable pulse numbers, this investigation, using the focal fields of a piezoelectric lithotripter, found no damage to murine kidneys at peak positive pressures as high as 40 MPa. Comparison of these cases and earlier bioeffects studies using pulsed, focused ultrasound leads to the conclusion that damage to murine kidneys is not simply correlated with peak positive pressure or peak negative pressure, nor is spectral content of the wave able to explain the striking differences in damage from these sources. With 200 individual shock waves from the piezoelectric lithotripter applied ventrally, 20-30% of the animals suffered superficial kidney damage (bleeding into the capsule), but the same exposure conditions produced severe intestinal hemorrhage in more than 80% of the animals.

Animals↗
PubMed1994

Plasmodium falciparum proteinases: cloning of the putative gene coding for the merozoite proteinase for erythrocyte invasion (MPEI) and determination of hydrolysis sites of spectrin by Pf37 proteinase.

Numerous proteinase activities have been shown to be essential for the survival of Plasmodium falciparum. One approach to antimalarial chemotherapy, would be to block specifically one or several of these activities, by using compounds structurally analogous to the substrates of these proteinases. Such a strategy requires a detailed knowledge of the active site of the proteinase, in order to identify the best substrate for the proteinase. Aiming at developing such a strategy, two proteinases previously identified in our laboratory, were chosen for further characterization of their molecular structure and properties: the merozoite proteinase for erythrocytic invasion (MPEI), involved in the erythrocyte invasion by the merozoites, and the Pf37 proteinase, which hydrolyses human spectrin in vitro.

Animals↗
PubMed1993

Sensitive, hydrosoluble, macromolecular fluorogenic substrates for human immunodeficiency virus 1 proteinase.

Hydrosoluble macromolecular fluorogenic substrates specific for the human immunodeficiency virus 1 (HIV-1) proteinase have been prepared. The fluoresceinyl peptide Ftc-epsilon-Ahx-Ser-Phe-Asn-Phe-Pro-Gln-Ile-Thr-(Gly)n, corresponding to the first cleavage site of HIV-1 gag-pol native precursor was linked to a water-soluble neutral (Lys)n derivative. The epsilon-aminohexanoyl residue (epsilon-Ahx) and the glycyl sequence were added in order to improve the stability of the substrate and the accessibility of the cleavage site to the HIV-1 proteinase respectively. This macro-molecular peptidic-substrate conjugate is significantly more water-soluble than the free peptide itself on a substrate molar concentration basis. The assay is based on the quantitative precipitation of the polymeric material by adding propan-2-ol whereas the fluorescent peptide moiety released upon proteolysis remains soluble in the supernatant. The proteinase activity is assessed by measuring the fluorescence of the supernatant. This assay allows the detection of a few fmol of HIV-1 proteinase, even in the presence of cell culture media, plasma or cell lysate and it gives accurate results within a large proteinase concentration range. The hydrosoluble macromolecular substrate is also suitable for determining the HIV-1 proteinase activity using 96-well microplates, allowing us to test accurately and rapidly numerous enzyme samples and/or the potency of new proteinase inhibitors.

Amino Acid Sequence↗
PubMed1993

Specific gene transfer mediated by lactosylated poly-L-lysine into hepatoma cells.

Plasmid DNA/glycosylated polylysine complexes were used to transfer in vitro a luciferase reporter gene into human hepatoma cells by a receptor-mediated endocytosis process. HepG2 cells which express a galactose specific membrane lectin were efficiently and selectively transfected with pSV2Luc/lactosylated polylysine complexes in a sugar dependent manner: i) HepG2 cells which do not express membrane lectin specific for mannose were quite poorly transfected with pSV2Luc/mannosylated polylysine complexes, ii) HeLa cells which do not express membrane lectin specific for galactose were not transfected with pSV2Luc/lactosylated polylysine complexes. The transfection efficiency of HepG2 cells with pSV2Luc/lactosylated polylysine complexes was greatly enhanced either in the presence of chloroquine or in the presence of a fusogenic peptide. A 22-residue peptide derived from the influenza virus hemagglutinin HA2 N-terminal polypeptide that mimics the fusogenic activity of the virus, was selected. In the presence of the fusogenic peptide, the luciferase activity in HepG2 cells was 10 fold larger than that of cells transfected with pSV2Luc/lactosylated polylysine complexes in the presence of chloroquine.

Amino Acid Sequence↗
PubMed1993

Triterpenoid glycosides from Stauntonia hexaphylla.

On the basis of spectroscopic and chemical methods, the structures of two new bisdesmosidic triterpenoid glycosides, named staunoside D and E, which were isolated from Stauntonia hexaphylla, were established as 3-O-(beta-D-glucopyranosyl(1-->2)-[beta-D- glucopyranosyl(1-->3)]-beta-D-glucopyranosyl)-hederagenin-28- O-[beta-D-glucopyranosyl (1-->6)-beta-D-glucopyranosyl] ester and 28-O-[alpha-L-rhamnopyranosyl (1-->4)-beta-D-glucopyranosyl(1-->6)-beta-D-glucopyranosyl]ester, respectively. Three known triterpenoid glycosides were also isolated. A new proglycoside was isolated from the cleavage of the ester-glycosidic linkage and its structure characterized.

Carbohydrate Sequence↗
PubMed1993

Triterpenoid glycosides from Stauntonia hexaphylla.

From Stauntonia hexaphylla, two new 3,28-bisglycosidic triterpenoid glycosides named staunosides A and B, were isolated along with three known triterpenoid glycosides, one of which was isolated from nature of the first time, though it had previously been obtained from the acid hydrolysate of kizuta saponin K12. On the basis of chemical and physicochemical evidence, the structures of staunosides A and B were elucidated as 3-O-(beta-D-glucopyranosyl)-hederagenin-28-O-[beta-D- glucopyranosyl(1-->6)-beta-D-glucopyranosyl]ester and 28-O-[alpha-L-rhamnopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->6)- beta-D-glucopyranosyl]ester, respectively.

Carbohydrate Sequence↗
PubMed1993

Iridium-192 high dose rate brachytherapy combined with external beam irradiation in non-resectable oesophageal cancer.

Forty-eight patients with non-resectable cancer of the oesophagus and oesophagogastric junction (group A: Stage I/II: n = 32; group B: Stage III/IV: n = 16) underwent intralumenal iridium-192 high dose-rate afterloading brachytherapy (5-7 Gy/session, total dose 5-21 Gy, mean 12.4 Gy) and external beam irradiation (Karnofsky > or = 80%: 50-60 Gy/2 Gy per day; Karnofsky 60%-79%: 30 Gy/3 per day). Prolonged satisfactory palliation (intake of at least semi-solid food) was demonstrated in 96% of patients. The mean survival for group A was 19.1 months and that for group B 6.9 months, with a 12-month survival rate of 66% for group A and 0% for group B (P < 0.001). Local tumour response and complication rate were significantly dose related with a predicted response rate of 70.5% and a complication rate of 50% at extrapolated response dose (ERD) 129.3 GY3 (Gy at alpha/beta = 3).

Adult↗
PubMed1993

Plasmodium falciparum proteinases and red blood cell invasion.

Malarial proteinases of the erythrocytic life-cycle are used to design new inhibitors capable of blocking the parasite's development. The Merozoite Proteinase for Erythrocytic Invasion (MPEI) of Plasmodium falciparum, a neutral proteinase, and the acidic Pf37 proteinase acting on spectrin as substrate, are good candidates for this kind of strategy.

Amino Acid Sequence↗
PubMed1993

[Ectopic teeth in the area of the paranasal sinuses].

In contrast to dentogenious affections of the sinus maxillaris ectopic or supernumerary teeth in the paranasal sinuses are seldom. Ectopic teeth located at the ostium of the sinus maxillaris are rare, intranasal teeth are very rare and ectopic/supernumerary teeth in the sinus etmoidalis are a curiosity. We report about two patients with such ectopic teeth. A 55 year old woman had a rootless tooth in her right sinus ethmoidalis which had caused a "pseudopolyposis" with consecutive nasal airway obstruction and severe headache. A 59 year old man had ectopic teeth in both sinus maxillaris which obstructed the left ostium, causing dumbness of the left cheek and severe headache. Both patients have been cured by operation. However the presented patients demonstrate that even elaborated radiological efforts could not prove diagnosis. The etiology, diagnostical steps and treatment of these teeth are discussed. The surrounding soft tissue should be examined histologically after resection of such a tooth to prevent the development of a residual cyst and to notice the extremely rare development of malignancies deriving from the highly potential tissue of the dental follicle.

Diagnosis, Differential↗
PubMed1993

The impact of resection margins in the treatment of primary sarcomas of the breast. A clinicopathological study of 8 cases with review of literature.

We reviewed the clinical and pathological features of eight patients (seven females, one male), who underwent surgery for sarcomas of the breast, to evaluate the effect of the margins of resection and histological tumor type on survival. Patients with carcinosarcoma, cystosarcoma phyllodes or dermatofibrosarcoma protuberans were excluded. Tumor size ranged between 4.5 and 26 cm (median 12.8 cm); there were three grade 3, four grade 2 and one grade 1 lesions. Of the five patients treated by radical resection margins, two with large grade 3 sarcomas died of distant metastasis 3 and 10 months later. One patient out of the five radical resected patients developed a local recurrence 96 months later. The recurrence was resected radically, radiotherapy was administered, and the patient is still alive at 168 months. The remaining four radical resected patients are free of disease until now. One of three patients, treated by wide or marginal resection, received adjuvant radiotherapy. This patient developed local recurrence and solitary distant metastasis at 26 and 49 months, respectively, and died of multiple distant metastasis at 54 months. Regional axillary lymph node metastasis was not observed in five patients in whom lymph node dissection was performed, with a median of 14.2 dissected lymph nodes. Two of eight patients received preoperative chemo- or radiotherapy because of large tumor size; five of eight received postoperative radiotherapy. Local tumor control was achieved in six of eight patients. The median follow-up time was 53.9 months (3-168 months), of all survivors median 72.2 months. Recurrence and disease-free survival rates were analysed according to histologic grade, tumor size, stage, surgical and adjuvant treatment.

Adult↗
PubMed1992

Labeled proteinase inhibitors: versatile tools for the characterization of serine proteinases in solid-phase assays.

Peptidyl chloromethyl ketones were used for the specific labeling of proteinases by attaching a biotin group to the N-terminal end of the peptide. Such labeled peptide inhibitors allowed the detection and quantitation of proteolytic enzymes immobilized on the plastic surface of a microtiter plate, as well as on nitrocellulose. The validity of these solid-phase assays was demonstrated using subtilisin Carlsberg as a model enzyme and biotinyl-epsilon-aminocaproyl-L-alanyl-L-alanyl-L-propyl-L-phenylal++ + anyl- chloromethyl ketone as a specific reagent. In addition to being usable for the screening of a particular proteinase in a large number of samples, these assays can be adapted for the analysis of specific proteolytic enzyme present in complex mixtures.

Amino Acid Sequence↗