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Biomedical subjects

F Hoffmann

Publications and source records attributed to F Hoffmann.

At least 145 records · Page 8Linked to original sources
PubMed1981

Valproic acid disposition in epileptic patients during combined antiepileptic maintenance therapy.

A previously developed mass spectrometric method was used to measure, in the presence of the unlabeled drug, the fate of pulse dose of tetradeuterated valproic acid given to epileptic patients. By this means the disposition of valproic acid (VPA) was studied in several epileptic patients on maintenance therapy with VPA and at least one other anti-epileptic drug. For 6 patients with 6 different anti-epileptic drug combinations, the mean VPA half-life was only 6.2 h, as compared to about 15 h after a single dose. The mean plasma clearance in those patients was 16.4 ml/min. The volume of distribution was 0.14 l/kg, which did not differ from values found in single dose studies. The clinical relevance of these findings is pointed out.

Adolescent↗
PubMed1981

Experimental data in keratophakia.

With the aid of a thermistor, the temperature decrease in corneal stroma during keratophakia is measured. 1 min after the beginning of the freezing process the temperature is -15 degrees C, 1 min later it is -40 degrees C, and 4 min after the beginning of the freezing process it is -50 degrees C. This temperature course is programmed into the constant rate freezer, in which any number of tissue samples can be frozen at the same time and with a reproducible freezing curve. The preliminary results indicate that under the use of different cryoprotective agents the radioactivity after 35S incorporation is 50-70% of the non-frozen control cornea.

Body Temperature↗
PubMed1980

"Arabidobrassica": Evidence for intergeneric somatic hybrid nature from electron microscopic morphometry of chromatin.

The new method of species and hybrid characterization and determination by quantitative morphometry of chromatin texture in ultra-thin sections of nuclei was applied to the somatic hybrid "Arabidobrassica" and its parents, Arabidopsis thaliana and Brassica campestris. The somatic hybrid exhibits the average amount of condensed chromatin, if compared to the proportion of condensed chromatin in nuclei of the parent species. This result corresponds to similar findings in natural allopolyploids and is consistent with the assumption that "Arabidobrassica" is a true intergeneric hybrid.

Brassica↗
PubMed1979

[Seasonal fluctuations in the sex ratio of new borns and the influence of the declining birth rate on the sex ratio (author's transl)].

Seasonal fluctuations in the sex ratio of new borns are investigated. The largest predominance of male deliveries over female deliveries was found to be during the conception months May-June with an almost constant number of deliveries. The highest value was in June. Seasonal maximum of the male to female sex ratio is concomitant to the seasonal maximum of conceptions. The investigation of the yearly sex ratio from 1958-1978 showed changes in the secondary sex ratio concomitant to the increase or decrease of the delivery rate. When the delivery rate decreased below 10 deliveries by 1000 population a reverse in the sex ratio was noted and the lowest number of male deliveries was found. This occurred although the number of first deliveries increased further with the decrease of multiparities. The reasons for this reverse trend in the sex ratio are discussed and a possible relationship to preceeding oral contraception is mentioned.

Birth Rate↗
PubMed1979

[Investigations into the hormonal regulation of the corpus luteum function in the human (author's transl)].

In estradiol micro-crystalline suspension was injected into the ovary containing the corpus luteum in women who underwent hysterectomy. The same complete luteaolysis is in women who did not have hysterectomies was obtained. The conclusion is drawn that the prostaglandins which are formed in the uterus have no influence in man on the regulation of the survival of the corpus luteum. As far as we know to date the high excretion of estradiol from the corpus luteum during the maturation of the corpus luteum forms an internal shuttle mechanisms for the survival of the corpus luteum which inhibits the biosynthesis of progesterone by estrogen and blocks the effect of the gonadatropins on the granulosa cells.

Adult↗
PubMed1978

[Local reaction and neutralization test in smallpox vaccination after previous inoculation with MVA. Stickl's graduated vaccination (author's transl)].

Of 200 first inoculations and 8 revaccinations, the sera were examined for content of neutralizing vaccine antibodies 3 weeks after the MVA graduated inoculation. In spite of imponderables which affect the failure rate in the "clinical trial", a positive result was obtained on first vaccination in 85%. In vaccinated children with a negative neutralization test a distinct booster effect was obtained with a "main vaccination" after about six months. The same effect was seen with revaccinations. For the time being inadequately controlled cerebral convulsive diseases, severe endogenous eczema, neurodermatitis, acute allergies, malignancies, immunosuppressive therapy, cortisole and intensive antirheumatic therapy and acute and purulent diseases must be considered as contraindications.

Adult↗
PubMed1978

[Cross-stitch suture in perforating keratoplasty (author's transl)].

50 perforating keratoplastic operations were performed with cross-stitch suture in about 1 1/2 years. In 10 patients, the cornea was directly transplanted from the eye of the donor to that of the patient; in 40 cases, the cornea of the donor had been preserved for a short time. 49 patients had a clear transplant at the time of discharge about 3 weeks after the operation.

Corneal Transplantation↗
PubMed1978

[Osteo-keramo-keratoprosthesis (author's transl)].

A high percentage of plastic keratoprosthesis is rejected again or intraocular infections occur because there is a cleft-like open junction between anterior chamber and lacrimal film. Only the ketratoprosthesis by Strampelli (1970) settles firmly in the cornea without the above risks, because the autogenous transplanted bone unites well with the grafted labial mucosa. 5 years of investigation have confirmed that glass ceramic Ceravital unites firmly with bones (Blencke et al. 1973, Strunz et al. 1977c, Bunte et al. 1977). For the osteo-keramo-keratoprosthesis Ceravital is used the same location as Dentin for the osteo-odonto-keratoprosthesis. The new surgical method has the advantage that 1. toothless patients can be operated, 2. the anterior chamber cannot flatten because the ceramic disk has the same shape as the corneal surface, and 3. broader optical cylinders can be used, by which a widening of the visual field is achieved.

Animals↗
PubMed1977

Mathematical consideration of aqueous outflow after trabeculo-electropunture (TEP).

The obtainable postoperative intraocular pressure following a TEP in a glaucoma patient with an intraocular pressure of 30 mm Hg is calculated in accordance with the concept that there is no outflow of aqueous humor along Schlemm's canal. If aqueous humor reaches all collector channel openings in the surgical area without resistance, the postoperative intraocular pressure reads 14.75 mm Hg. This intraocular pressure is obtained at a point when a collector channel of 1 mm length and of 32 mum in diameter or two collector channels of 27 mu in diameter or five collector channels of 22 mu in diameter establish connection with the trabecular opening.

Aqueous Humor↗
PubMed1977

Schlemm's canal after trabeculo-electropuncture (TEP).

The Schlemm's canals of two patients were examined histologically and electron-microscopically. The first patient had a tumor of the choroid. An electroprobe was inserted into the Schlemm's canal and then removed. In this eye, nearly all septa and almost the entire endothelial layer of the lumen were destroyed in the area of the inserted probe. The second tissue sample came from a patient who had had TEP surgery 2 years earlier and whose intraocular pressure had increased again. The preoperative gonioscopic examination showed an opening in the trabecular network, with blood evading from Schlemm's canal. Histologically, an opening approximately 50 micron wide, lined with endothelium, was found in the trabecular network. The lumen of the canal existed only in a section approximately 500 micron long. Elsewhere the inner and outer walls of the Schlemm's canal adhered to each other. In the area of this 500 micron long section of the canal, only one collector channel could be found. Thus, the insufficient decrease in intraocular pressure after operation can be explained by the side-effects of the insertion of the electroprobe into the Schlemm's canal.

Choroid Neoplasms↗
PubMed1977

Trabeculo-electropuncture in cynomolgus monkeys (Macaca irus).

Trabeculo-electropuncture (TEP) was performed in one eye of ten cynomolgus monkeys. In five control eyes, the TEP probe was inserted into Schlemm's canal and withdrawn without causing a spark discharge. In another five control eyes,a scleral window was produced and the canal was opened, but no probe was inserted. The gross facility of outflow was determined prior to the operation and 2, 6, and 18 weeks postoperatively. TEP had no longlasting effect on the facility. Gonioscopy five months after the operation revealed marked changes in the anatomy of Schlemm's canal in treated eyes and in control eyes subjected to probe insertion. Control eyes without probe insertion appeared normal. Six months postoperatively three monkeys were killed and the eyes investigated. Light and electron microscopy indicated that insertion of the probe with or without spark discharge resulted in the formation of dense bridges between the inner and outer walls of Schlemm's canal. At the sites of TEP, the trabecular meshwork was replaced by dense scar tissue containing irregular, fine fibrillar material, elastic fibres and large amounts of curly collagen. There were no intertrabecular spaces in the scar tissue. In one eye, one lesion was covered by a thin endothelium resting on a basal membrane. The results indicate that the failure of TEP in monkey eyes was due to the formation of dense scar tissue occluding the openings initially produced by the spark discharge.

Animals↗
PubMed1976

[Dendritic lesions in herpes simplex infection of the cornea. Scanning and transmission-electron microscope findings (author's transl)].

Thirty rabbits were divided into 10 groups of 3 animals. In the case of each animal 1 drop of Herpes virus hominis suspension (HVH) was applied to the intact cornea of the right eye. Within the period between the 2nd and 20th day after infection occurred, three animals were killed each time and the corneae were examined by scanning- and transmission-electron microscope. Circular foci and dendritic lesions were observed starting with the 4th day. After the 12th day, dendritic lesions could no longer be observed. Circular foci and dendritic lesions possess a width of about 200 mu which remains unchanged during the entire observation period. The areas of ulceration are obscured by lateral epithelium migrations. The observation that epithelial lesions do not change their demensions over an extended period of time, speaks for an approximate time balance between cellular damage caused by the viruses and the migratory speed of the epithelium. This mechanism is disrupted in the neighboring circular foci. The cytotoxic effect is predominant. Circular foci are confluent. The dendritic lesion so characteristic for herpes simplex infection of the cornea is explained by the confluence of several circular foci which are accidentally positioned next to each other.

Animals↗
PubMed1976

[Suture technique for perforating keratoplasty (author's transl)].

The usual suture techniques in connection with perforating keratoplasty and the pulling direction of the threads are described. Especially unfavorable are the verticle factors with relation to the radial and diagonal continuous suture, which necessarily lead to a gaping of the inner and outer wound fissure. The double continuous diagonal suture (cross-stitch suture) seems to come closest to the goal of attaining as uniform a sealing of the wound fissure as possible with as small an amount of suture material as possible. This suture technique is therefore recommended for perforating keratoplasty.

Cornea↗