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Biomedical subjects

F Hoffmann

Publications and source records attributed to F Hoffmann.

At least 109 records · Page 6Linked to original sources
PubMed1986

Ultrastructure of the rabbit corneal stroma after experimental keratomileusis.

Experimental keratomileusis operations were performed on 13 rabbit eyes. The corneas of the rabbits, in particular the stroma, were investigated up to 24 months after the operation by light and electron microscopy. The most striking features of the corneal ultrastructure following experimental keratomileusis were the presence of abnormal collagen fibrils and electron-translucent vacuoles in the interface.

Animals↗
PubMed1986

[Effect of cyclosporin A, dexamethasone and various preservatives on epithelial wound healing in the denervated guinea pig cornea].

In order to examine a possible connection between punctate keratopathy following keratoplasty and the various drugs used in postoperative treatment, denervation was performed in white Pirbright guinea pigs by corneal trepanation with a 6 mm trephine to a depth of 0.25 mm. One week later an iodine gas applicator was used to produce erosion in the cornea, which had healed in the meantime. Until the erosions healed, the corneas were photographed four times daily after fluorescein staining; the negatives were enlarged by projection and the erosions measured planimetrically. The linear regression method was used to calculate a compensating straight line and thus the hourly epithelial wound-healing surface (mm2/h) for each eye. This was 0.76 mm2/h in control eyes. Dexamethasone 0.1%, benzalconium chloride 0.01%, and chlorobutanol 0.2% did not significantly inhibit wound healing, while Spersadex (dexamethasone 0.1% + benzalconium chloride 0.01%) and Totocortin (dexamethasone 0.1 + chlorobutanol 0.2%) did. Polyvinyl alcohol (1.4% without preservative) significantly delayed epithelial wound healing. Cyclosporin A 2% (in castor oil) had no influence on epithelial wound healing.

Animals↗
PubMed1986

[Pathogenesis of hurricane keratitis].

Hurricane keratitis is an epithelial disorder of corneal transplants which occurs irrespectively of the type of local postoperative therapy used. The epithelial defects show a vortex-like arrangement resembling satellite photos of whirlwinds. Even before the development of punctate keratitis, fluorescein staining of the corneal surface reveals vortex-like figures corresponding to a varying thickness of the tear film in a vortex-like configuration. The irregularities in the tear film are due to an irregular profile of the corneal surface, the functional result of which is irregular astigmatism. The irregular surface profile in turn is caused by the approximation of incongruent wound edges and by sutures being too tightly drawn. Particularly when Healon is used, there is a tendency to draw the sutures tight, since a postoperative pressure increase with subsequent fistulation must be expected. Hurricane keratitis thus also appears to result indirectly from the use of Healon.

Cornea↗
PubMed1986

[Bioavailability of a valproic acid preparation. The relative bioavailability of enteric-resistant valproic acid preparations in tablet form with simultaneously administered tetradeuterated valproic acid as the bioavailability reference].

The relative bioavailability was measured for the 150-, 300-, and 600-mg enteric coated Leptilan tablets (valproic acid, sodium salt) using a new method. Simultaneously an equimolar amount of a tetradeuterated valproic acid - di-(2,3-dideutero-n-propyl)-acetic acid - was given as an aqueous solution of the sodium salt. This methodology excludes effects on the two partial pharmacokinetics caused by time-dependent intraindividual variations of the metabolising capacity or other biochemical or physiological changes in the body of the volunteer. Therefore, this methodology gives already reliable data for bioavailability when using only small numbers of volunteers. The relative bioavailability of the enteric coated Leptilan tablets was 95.5 +/- 0.6%, 104.4 +/- 7.6%, and 100.7 +/- 2.4% (mean from experiments with 3 volunteers each) for the 150-, 300-, and 600-mg tablets respectively.

Adult↗
PubMed1986

Pharmacokinetic of topical cyclosporin A in the rabbit eye.

3H labelled cyclosporin A (CS-A) eye drops (2% in castor oil) were applied in rabbits. When a single drop of 10 microliters was given CS-A reached a maximal concentration of 900-1400 ng/ml in the cornea 6 hr after application and then slowly decreased. A substantial level of 600-900 ng/ml was still present after 48 hr. When corneas were analysed for their cellular compartments, 67% of CS-A was found in the epithelium, 25% in the stroma (probably in keratocytes), and 8% in the endothelium. In corneas denervated by circular keratotomy, slightly reduced concentrations were found after surgery, the reduction was not therapeutically significant. Using the HPLC method a significant corneal metabolism of CS-A could be excluded. Scleral concentrations of CS-A as high as 180 ng/ml were found. Concentrations of CS-A in aqueous humor, lens, vitreous body and uvea/retina were below the therapeutic range.

Animals↗
PubMed1985

[Local treatment of corneal transplants in the human with cyclosporin A].

Cyclosporin eye drops (2% in miglyol) were administered in 4 glaucoma patients for postoperative treatment following keratoplasty. In the course of the 2-year follow-up period, one patient evidenced an immunoreaction that led to clouding of the transplant. In 25 patients, Cyclosporin eye drops (2% in castor oil) were given in combination with low-dose dexamethasone eye drops (0.1%). During a mean follow-up period of 10 months (5 to 14 months), 4 transplants clouded as the result of an immunoreaction. The intraocular pressure was not influenced by the combination therapy in 21 patients who did not have a history of glaucoma but increased slightly in 3 of 4 patients who did. Since Cyclosporin A had no influence on the stromal wound healing, it was possible to remove the corneal sutures 5 months postoperatively. All patients developed keratopathia punctata and slight conjunctivitis. The epithelial defects, which often showed a vortex-like pattern, appeared at the end of the first postoperative week and were usually no longer detectable after 4 months. The tear production (Schirmer test) was not influenced or only slightly increased by Cyclosporin. Corneal infiltrates did not occur. If one compares the effects and side effects of Cyclosporin and dexamethasone, local application of Cyclosporin in combination with low-dose dexamethasone appears to be an effective treatment for corneal transplantation in Man.

Adult↗
PubMed1985

Prebioptic psychological characteristics of breast cancer patients.

63 women were examined the day before breast biopsy using psychological ratings, speech analysis and questionnaire testings. Ratings revealed differences (benign vs. malignant, a = 5%) in 8 of 10 scales, cancer patients being inaccessible, altruistic, suppressing feelings, rationalizing and harmonizing. The biopsy's result was predicted in 75% of all cases. Questionnaire testing showed differences in 7 of 16 scales. It proved cancer patients to be more dependent, anxious, aggressive, health-conscious, family-bound and antisexual. A discriminant analysis correctly identified 77% of cancer and 87% of benign patients. Speech analysis (Gottschalk-Gleser) revealed only minor differences: fewer aggressive and more anxious utterances from cancer patients. Conclusions are drawn for the care and treatment of breast cancer patients.

Adaptation, Psychological↗
PubMed1985

Keratomileusis, keratophakia and keratokyphosis.

Using cryo-refractive corneal surgery, it is not yet possible to attain a post-operative visual acuity corresponding to that achieved with a contact lens. This is due to the tissue changes caused by the cryoprocess as well as to the interlamellar corneal scar. A description is given of keratokyphosis, a procedure by means of which the outer radius of the cornea can be altered without having to freeze the corneal stroma. The principle of the surgical technique consists of the removal of centrally thinned corneal discs from the patient's eye using a newly developed microkeratome. Subsequent suturing in of a donor corneal lamella leads to a protrusion of the corneal surface and thus to an alteration of the refractive power.

Corneal Transplantation↗
PubMed1984

Dimethyl sulfoxide can initiate cell divisions of arrested callus protoplasts by promoting cortical microtubule assembly.

A serious problem in the technology of plant cell culture is that isolated protoplasts from many species are reluctant to divide. We have succeeded in inducing consecutive divisions in a "naturally" arrested system-i.e., protoplasts from a hibiscus cell line, which do not divide under standard conditions-and in an artificially arrested system-i.e., colchicine-inhibited callus protoplasts of Nicotiana glutinosa, which do readily divide in the absence of colchicine. In both cases, the reinstallation of a net of cortical microtubules, which had been affected either by colchicine or by the protoplast isolation procedure, resulted in continuous divisions of the formerly arrested protoplasts. Several compounds known to support microtubule assembly in vitro were tested for their ability to promote microtubule assembly in vivo. Best results were obtained by addition of dimethyl sulfoxide to the culture medium. Unlimited amounts of callus could be produced with the dimethyl sulfoxide method from protoplasts which never developed a single callus in control experiments.

Journal Article↗