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Biomedical subjects

P Grote

Publications and source records attributed to P Grote.

13 recordsLinked to original sources
PubMed2001

Crystal structure of aphrodisin, a sex pheromone from female hamster.

We have solved the crystal structure of aphrodisin, a pheromonal protein inducing a copulatory behaviour in male hamster, using MAD methods with selenium, at 1.63 A resolution. The monomeric protein belongs to the lipocalin family, and possesses a disulfide bridge in a loop between strands 2 and 3. This disulfide bridge is characteristic of a family of lipocalins mainly identified in rodents, and is analogous to the fifth disulfide bridge of the long neurotoxins, such as alpha cobratoxin. An elongated electron density was found inside the buried cavity, which might represent a serendipitous ligand of unknown origin. The analysis of the water accessible surfaces of the side-chains bordering the cavity indicates that Phe76 may be the door for the natural ligand to access the cavity. This residue defines the entry of the cavity as belonging to the consensus for lipocalins. The face bearing Phe76 might also serve for the interaction with the receptor.

Amino Acid Sequence↗
PubMed1979

[In vivo-measurements of the latitude of Schlemm's canal in buphthalmos (author's transl].

In 9 cases of buphthalmos 'in vivo-measurements of the latitude of Schlemm's canal gave us a mean value of 678 micron. The extreme values ranged between 600 micron and 800 micron. Therefore these values differ significantly from those measured 'in vivo' in chronic simple glaucoma (x:542 micron, extreme values 425 micron and 625 micron). The latitude of Schlemm's canal correlates with the diameter of cornea and the rise of intra-oculare pressure. In cases of buphtha-mos the success of trabeculotomy seems to be better, if the latitude of Schlemm's canal is less than l50 micron. Trabeculotomy should therefore be performed as soon as possible.

Chronic Disease↗
PubMed1978

[Indications for the location of trabeculotomy in simple glaucoma. I. The blood contents of Schlemm's canal].

Following trabeculotomy, about 30% of glaucomatous eyes are not normalized in pressure without additional therapy. In these cases, it was not possible to remove the resistance of outflow completely. Before deciding to perform trabeculotomy it is, therefore, necessary to localize the resistance of outflow. The inspection of the blood pattern in Schlemm's canal gives no indication where to localize the resistance of outflow. The same holds true for the haemorrhage deriving from Schlemm's canal, in the operating field (trabeculotomy window), which appears in 19.2% of cases. After trabeculotomy the blood outflow into the anterior chamber is significantly higher (63.6%) using the suction cup, then following pressure of the gonioscopy lens (28.1%). The differences between these findings are discussed. Our results indicate the necessity to search for other methods in localizing the resistance of outflow pre-operatively.

Aqueous Humor↗
PubMed1978

[Indications for the location of trabeculotomy in simple glaucoma. II. The demonstration of aqueous outflow with fluorescein].

Iontophoresis is less apt to prove the existence of outflow channels of aqueous humour, but it is appropriate in demonstrating filtering blebs. After injecting fluorescein directly into the anterior chamber, the outflow channels are clearly marked in enucleated non-glaucomatous eyes, as well as in eyes containing a tumor, prior to enucleation. Regularly, one is able to observe sectors in which the aqueous veins are filled slowly or not filled at all. Injecting fluorescein directly in Schlemm's canal proves that in cadaver eyes without glaucoma the lumen is open all around. Sectorial filling defects of vessels leading out of Schlemm's canal are often seen. In three patients with simple glaucoma blocking of dye was noticed during passage through Schlemm's canal without reappearance. Our experiments give the impression that segmental division of Schlemm's canal is more marked in eyes with glaucoma than in normal eyes. If local occlusions within Schlemm's canal are of importance for the range of lowering of intraocular pressure, one must differentiate between the trabecular and the intrascleral part of the resistance of outflow in the operation field, in order to choose the best operating procedure. Such a differentiation seems, in principle, possible using fluorescein--primarily injected into the anterior chamber directly, and secondarily into a given part of Schlemm's canal.

Anterior Chamber↗
PubMed1978

[A new probe for trabeculotomy (author's transl)].

The possibility of complications connected with trabeculotomy led us to the development of the so-called hook probe. Instead of being twisted into the anterior chamber the probe is successively pulled back into Schlemm's canal, thereby tearing the trabecular meshwork. Complications connected with the turning of the probe can thus be avoided. Three techniques of trabeculotomy are compared: Harms trabeculotomy, with the turning of the probe over 60 degrees or 120 degrees and trabeculotomy with the hook probe over 60 degrees of the circumference. This use of the hook probe results in minimal trauma to the anterior part of the eye. Hemorrhaging particularly is infrequent or often even absent, during the cutting of the trabecular meshwork. The influence on intraocular pressure does not significantly differ between use of the hook probe and use of Harms probe. The dependence of intraocular pressure on length of tearing distance could not be determined. The results give the impression that a portion of the outflow resistance-at least postoperatively-within a greater percentage of simple glaucoma eyes lies distally to the trabecular meshwork. In choosing the best technique for operating, it is therefore important to know whether the outflow resistance in each individual case is mainly localized trabecularly or intrascleraly.

Follow-Up Studies↗
PubMed1978

[Experiences with transtrabecular iridectomy].

A transtrabecular iridectomy was performed in 17 eyes with narrow angle glaucoma, and in 3 eyes in which the trabecular meshwork was gonioscopically not visible. Postoperatively, the conjunctive lied directly on the sclera in 14 cases; in 6 cases a circumscribed conjunctival bleb developed in the operation field. After a follow-up of 12 or 24 months, the intraocular pressure was normalized without miotics in 15 of 17 eyes. The mechanism of transtrabecular iridectomy is discussed.

Follow-Up Studies↗
PubMed1978

[Attempt to minimize postoperative trauma after trabeculotomy].

We tried to modify the technique of trabeculotomy in order to minimize the trauma to the anterior part of the eye, when tearing the trabecular meshwork. (1) With help of an annular probe, having a lumen, a nylon thread is pushed through Schlemm's canal and the trabecular meshwork cutted circumferentially. (2) With a 'flat probe', corresponding to the configuration of Schlemm's canal, the trabecular meshwork is torn. (3) A so-called 'hook probe' is described, which tears the trabecular meshwork while being sucessively pulled backwards. According to our experiments, the usefulness of the thread technique and of the 'flat probe' is not yet to be decided upon. On the other hand, the advantages of the 'hook probe' are clearly visible, in avoiding the complications connected with twisting the probe into the anterior chamber.

Glaucoma↗
PubMed1976

I[In vivo measurements of the lumen of Schlemm's canal in chronic simple glaucoma].

"In vivo" measurements of lumen of Schlemm's canal were performed on 38 eyes with trabeculotomy made for chronic simple glaucoma. The mean value of lumen was 542 mum, much higher than the mean values measured on cadavers and quoted in literature. Contraction due to fixation and dehydration may be the main cause of those differences.

Chronic Disease↗
PubMed1976

[Increase in the lumen of Schlemm's canals with increase in ultraocular pressure].

The lumen of Schlemm's canal increases "in vivo" and in experiments on cadaver eyes, with the increase of intra-ocular pressure. It is accepted that the trabecular structures are extended with the raise of inra-ocular pressure. The relation of "in vivo" measurements of the canal with the intra-ocular pressure does not allow any conclusions to be drawn about localisation of outflow obstructions. The viriations of the obtained values is an expression of structural differences in the canal lumen.

Ciliary Body↗
PubMed1975

[Giantcell arteriitis and ophthalmodynamogram (author's transl)].

Report on seven patients with giantcell arteritis. An ophthalmodynamographic finding typical for these aspects of case was recorded in all cases. In one-sided and permanently one-sided functional disturbances, too, a pathologically reduced pulsation volume on both sides could always be derived.

Blindness↗
PubMed1975

[Transtrabecular iridectomy - a new surgical technique in the treatment of chronic narrow-angle glaucoma (author's transl)].

A new surgical technique in the treatment of chronic narrow-angle glaucoma is described. After forming a scleral flap and opening of Schlemm's canal a probe is inserted into the canal. We dissect the sclera and the outer wall of Schlemm's canal by an oblique cut. The probe being retracted again, the trabecular meshwork is cut and a basal iridectomy is performed. Then the scleral cut and the trabecular window are closed tightly. Postoperative pressure behaviour and gonioscopy indicate, that the outflow of aqueous humour occurs via trabecular cleft and the collector channels in the operating field; obviously with this technique the intrascleral outflow channels can be saved to a great extend.

Chronic Disease↗