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Biomedical subjects

F Hoffmann

Publications and source records attributed to F Hoffmann.

At least 91 records · Page 5Linked to original sources
PubMed1989

A simple plant and tissue culture growth chamber for the regeneration of tobacco mesophyll protoplasts.

The isolation and regeneration of tobacco mesophyll protoplasts from fully developed leaves, an important methodological step in plant genetic engineering as well as in plant cell biology and physiology, has been proven unreliable to the extent that it has become a significant setback to basic research. This unfortunate situation is primarily due to the suboptimal physiological state of greenhouse-grown protoplast donor plants. A technically simple and inexpensive method, based on the utilization of commercial Phototron units, is described for the production of suitable tobacco donor plants. Furthermore, a modified version of such a culture unit can be used to regenerate plants from protoplast-derived calli.

Atmosphere Exposure Chambers↗
PubMed1989

Predisposing factors in corneal graft rejection.

During a period of 12 years, 390 patients were treated with perforating keratoplasty and given regular annual follow-ups. Of these, 357 records were evaluated, and there was a 20% incidence of immunoreactions. The transplants were assessed according to four criteria and subdivided into a low-risk and a high-risk group. For high-risk patients, the relative risk of developing an immunoreaction was 2.9 times greater with subdivision according to the preoperative diagnosis, 2.1 times greater with a transplant diameter of 7.5 mm or more, 2.6 times greater with compatibility between fewer than two HLA-B or -DR antigens of the donor and recipient, and 4.2 times greater with blood or fibrin in the anterior chamber on the first postoperative day. There was a linear relation between the frequency of being placed into the less-favorable-prognosis group and the occurrence of an immunoreaction.

Child↗
PubMed1987

[Significance of progesterone production in regulating the menstrual cycle].

Premature luteolysis, which can be brought about by injection of a crystalline suspension of estradiol into the ovary carrying the corpus luteum, is cancelled out by a concomitant injection of an appropriate dose of a crystalline progesterone suspension, together with a simultaneous increase in the plasma progesterone level. The authors discuss whether preovulatory production of progesterone has a similar protective influence on the growth and estrogen and androgen production of the vesicular ovarian follicles and the dominant follicle.

Corpus Luteum↗
PubMed1987

[Combination of phacoemulsification and trabeculectomy. Results of a retrospective study].

Combined trabeculectomy and phacoemulsification was performed on 21 eyes with poorly controlled glaucoma (15 open-angle glaucomas, 5 capsular glaucomas, and one secondary glaucoma) and coexisting cataract. In 20 of these eyes there was severe glaucomatous damage of the optic nerve with visual field loss. With the procedure used by the present authors there was a higher incidence of choroidal detachments, whereas other complications occurred at a lower rate than reported by other authors combining cataract extraction and trabeculectomy. Mean IOP was lowered from 25.7 +/- 6.1 to 17.1 +/- 3.2 mmHg after 18 months. Thirteen patients (62%) required no medication, while 5 (24%) required additional therapy for sufficient control of IOP (less than or equal to 21 mmHg). The results indicate that the combined phacoemulsification and trabeculectomy procedure may be a useful approach in eyes with severe glaucomatous damage and cataract.

Aged↗
PubMed1987

Human immunodeficiency virus transmission by organ donation. Outcome in cornea and kidney recipients.

The human immunodeficiency virus (HIV) is reportedly transmitted by sexual contact, sharing of infected needles among intravenous drug abusers, blood and blood products, artificial insemination, and kidney transplantation. This study reports on cornea and kidney recipients of two HIV-infected donors. HIV was transmitted to two kidney recipients who developed symptoms of acute HIV infection (i.e., fever, leukopenia, mild thrombopenia, splenomegaly) starting 12 days after transplantation. These signs of acute infection ended with seroconversion of HIV antibodies on approximately the 56th day after transplantation. The three cornea recipients showed no signs of acute infection and no HIV antibodies were detected up to three years after transplantation. The nontransmission observed in our cases, however, may not be representative of cornea transplantations in general. HIV is neurotropic in the later stages of the disease, and transmission of other neurotropic viruses like rabies and Creutzfeldt-Jakob disease by cornea transplantation has been reported. All tissue and organ donors should be tested for anti-HIV prior to donation.

Acquired Immunodeficiency Syndrome↗
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↗