Experimentally induced calcium oxalate keratopathy in rabbits

In a period of 21 days, six subcutaneous injections of calcium chloride and dibutyloxalate solution produced a flecklike, polymorphous corneal opacity and a slight stromal clouding in chinchilla rabbits, as seen with the slit lamp. In front of the endothelium, opaque structures could be seen with the specular microscope. New Zealand white rabbits showed only a diffuse corneal clouding. Light microscopy revealed a reticular alteration of the cytoplasm in the basal layers of the corneal epithelium primarily in chinchilla bastard rabbits. In central corneal areas an irregular structure of the basal epithelial cells and a papillalike alteration of the stromal-epithelial border was seen. In the endothelium an increased formation of vacuoles was observed in both species. Scanning electron microscopy demonstrated endothelial cell loss.

[Experimental tyrosine keratopathy in rabbits]

Tyrosine was given to White New Zealand and Chinchilla bastard rabbits. The corneal epithelium showed pinpoint lesions and a pseudokeratitis dendritica from the fourth day on. In spite of continued tyrosine dosage these lesions disappeared clinically within 6 days. Scanning electron microscopy revealed necrosis of isolated epithelial cells even after the twentieth day of tyrosine dosage. Specular microscopy sporadically revealed glittering pre-endothelial structures. It was found by light microscopy that there was a tendency to focal proliferation of corneal epithelial cells and a vacuolization in the basal epithelial cell layers. Endothelial defects may be responsible for circumscribed edema of the corneal stroma.

The nonclassical insulin binding of insulin receptors from rat liver is due to the presence of two interacting alpha-subunits in the receptor complex

The binding characteristics of the insulin receptor tetramer (alpha 2 beta 2) and dimer (alpha beta) were examined. Unlabelled insulin enhanced the dilution-induced dissociation only of the receptor tetramer-bound 125I-insulin. Furthermore, when both the receptor forms had been preincubated with anti-receptor-antibodies (B9-antiserum), insulin binding only to the receptor tetramer but not to the dimer was inhibited. However, both oligomers are not immunologically distinct since more than 80% of the two forms were immunoprecipitated by the antiserum. These results suggest that both insulin and anti-receptor-antibodies induce cooperative interactions between the two linked alpha-subunits of the receptor tetramer leading to a decrease in insulin binding of this receptor form.

Characterization of solubilized insulin receptors from rat liver microsomes. Existence of two receptor species with different binding properties

Insulin receptors were solubilized from rat liver microsomes by the nonionic detergent Triton X-100. After gel filtration of the extract on Sepharose CL-6B, two insulin-binding species (peak I and peak II) were obtained. The structure and binding properties of both peaks were characterized. Gel filtration yielded Stokes radii of 9.2 nm (peak I) and 8.0 nm (peak II). Both peaks were glycoproteins. At 4 degrees C peak I showed optimal insulin binding at pH 8.0 and high ionic strength. In contrast, peak II had its binding optimum at pH 7.0 and low ionic strength, where peak I binding was minimal. For peak I the change in insulin binding under different conditions of pH and ionic strength was due to a change in receptor affinity only. For peak II an additional change in receptor number was found. Both peaks yielded non-linear Scatchard plots under most of the buffer conditions examined. At their binding optima at 4 degrees C the high affinity dissociation constants were 0.50 nM (peak I) and 0.55 nM (peak II). Sodium dodecyl sulfate/polyacrylamide gel electrophoresis of peak I revealed five receptor bands with Mr 400 000, 365 000, 320 000, 290 000, and 245 000 under non-reducing conditions. For peak II two major receptor bands with Mr 210 000 and 115 000 were found. The peak II receptor bands were also obtained after mild reduction of peak I. After complete reduction both peaks showed one major receptor band with Mr 130 000. The reductive generation of the peak II receptor together with molecular mass estimations suggest that the peak I receptor is the disulfide-linked dimer of the peak II receptor. Thus, Triton extracts from rat liver microsomes contain two receptor species, which are related, but differ considerably in their size and insulin-binding properties.

[Carotinoid retinopathy. III. Reversibility]

Twenty-five patients (erythropoietic protoporphyria 23, polymorphous light eruption 1, "cosmetics" 1) were re-examined 2-10 months after therapy with beta-carotene and canthaxanthine was discontinued. Dark adaptation and ERG parameters had normalized, whereas crystalline retinopathy and pigment epithelial defects showed no signs of reversibility.

[Permanent central venous access in chronically-ill children]

15 patients aged 8 months to 18 years received implanted venous access catheters. Blood sampling and continuous infusions up to 52 days were performed via these devices. The systems were used for 18-166+ days and implanted for 18-635+ days. The complication rate was low and seems to be dependent on the experience of the caretaker. The systems are a valuable addition in the care of chronic sick children and offer new perspectives of therapy.

[Carotinoid retinopathy. II. Electrophysiologic findings in 23 carotenoid-treated patients]

Twenty-three patients on long-term therapy (up to 14 years) with carotenoids (up to 336 g) were tested electrophysiologically. The EOG revealed a small but not significant delay of the light peak. Arden's ratio, however, was normal. The ERG was depressed as far as photopic activity was concerned. At low dosages of carotenoids the scotopic ERG amplitudes were found to be hypernormal, whereas at higher dosages the increase in amplitude during dark-adaptation was markedly delayed. There was a dose-dependent prolongation of b-wave implicit time and a dose-dependent reduction in oscillatory potentials. The marked effect on the b-wave and on the oscillatory potentials and the site of the retinal crystals permit the assumption that a mechanism of carotenoid action is located in the middle layers of the retina.

[Dissolution processes and surface alteration. 4. Determination of the "effective" surface]

A method is described for measuring the "effective" surface of a drug by means of dissolution parameters using the Paddle-model or a resorption-model respectively. The obtained values were compared with the specific surface which was determined by BET-technique. The "effective" surfaces obtained by means of the dissolution parameters are smaller than those determined BET-technique.

[Carotenoid retinopathy. I. Morphologic and functional findings]

Thirty patients who had undergone long-term treatment with carotenoids (max. 14 years and 336 g of carotenoids) were examined. Ophthalmoscopy revealed retinal crystals in 20 patients. The retinal crystals were usually located around the macula, forming a ring, and in one case they were even found in the macula itself. No deterioration of visual acuity or visual field defects were found, but there was a markedly dose-dependent prolongation of the duration of dark adaptation.

[Central areolar choroidal dystrophy with retinal crystals]

Central choroidal dystrophy is characterized by lack of large parts of the central choroid. In the dystrophic region outer retinal layers are also involved whereas inner retinal layers may be unaffected. Three patients with central choroidal dystrophy and retinal crystals in the dystrophic region or near its border are described. Predominantly, these crystals are located in the inner or middle retinal layers. The amplitude of the electroretinogram is reduced according to the extent of the defect in the neurosensory epithelium. In the cases described here the inner retinal layers may also be involved in the pathologic process. In two patients with the most marked clinical and electrophysiological disturbances, a multiple lipoprotein-type hyerlipidemia was found.

[Central chorioretinal dystrophy with drusen and retinal crystals]

4 patients out of 2 pedigrees present an association of dominant drusen, central chorioretinal dystrophy and retinal crystals. It seems to be transmitted in an autosomal dominant mode. Drusen have also been found in 4 patients (3rd generation) at the age of 40 years. Central chorioretinal dystrophy and retinal crystals have not been found prior to the age of 60 years. Visual acuity and central scotoma depend on the central chorioretinal dystrophy. Electro-oculograms and electroretinograms exhibited relatively little changes. 2 patients showed phenotype II and IV of Fredriksen.

[Dissolution processes and surface changes. 3. Determination of the surface with the BET process]

Two methods are demonstrated for the determination of the surfaces of solid substances by the BET-method. Using a newly constructed apparatus substances with high specific surfaces can be determined by the two-point-method with a good precision. For the determination of pulverous drugs we used the one-point-method proposed by Haul and Dümbgen [2] improving it in calibration und practicability.

Mathematical kinematics in engineering of endoprostheses. Evaluation of the results of gait analysis

Certain optical methods (photogrammetry) achieve great precision in analysis of body motion. However, this study clearly shows that the tracing of body surface movement is unsuitable for analysis of actual joint motion, at least in the knee joint, because of the soft tissue shifting which occurs. It is also shown that comparatively simple mathematical-kinematic techniques can be used to check the degree of error of methods of measurement in orthopedics. It is to be assumed that no currently available knee joint prostheses function in a kinematically perfect manner. If the movement of knee joint prostheses is to be optimized and implantation errors affecting kinematics avoided, it seems indispensable, at the current level of technology, to employ X-ray stereophotogrammetry to describe natural knee joint motion.

[Crystalline chorioretinopathy with marginal corneal involvement]

The authors describe central and peripapillary chorioretinal dystrophies seen in 3 patients. In 2 of them a crystalline chorioretinal dystrophy was found. This is compared to the "simple" chorioretinal dystrophy of the third patient. Crystalline deposits in the limbus corneae were found in both patients with crystalline chorioretinopathy. Higher serum cholesterol levels and more widespread chorioretinal dystrophy are associated with greater corneal involvement. Visual acuity, central scotomata and the changes in the electroretinograms correlate with the chorioretinal dystrophy. The crystalline chorioretinopathy found in these patients is associated with Fredriksen's phenotype II, whereas the "simple" form of chorioretinal dystrophy is associated with multiple lipoprotein-type hyperlipidemia.

Developmental expression of the white locus of Drosophila melanogaster

We have isolated several cDNA clones of the white locus which are derived from embryonic and pupal transcripts of Drosophila melanogaster. The cDNA sequences map within 7.5 kb (coordinates -3.0 to +4.6) of the genomic DNA and correspond mainly to sequences within the distal region of the gene (coordinates -0.2 to -3.0). A major RNA species of 2.6 kb was detected on Northerns of poly(A) RNA isolated from all developmental stages. The total accumulation of this transcript peaks in the mature third instar larva to a level of 0.003% which is about ten times higher than that observed in embryos. The spatial distribution of white locus transcripts was determined by in situ hybridization to tissue sections. In embryos, hybridization signals are restricted to the cells of the developing Malpighian tubules and the signal strength corresponds with 50 transcripts per cell. Before the termination of the third instar stage, hybridization signals are also detected at a comparable level in the eye antennal disks. At the same stage, a third site of labeling is observed over a small cluster of cells which seems to be associated with the larval photoreceptor organs. Thus, white locus expression is largely restricted to tissues which are known to be involved in the biosynthesis of eye pigments and these different cell types act in a temporally autonomous manner with respect to the induction of the white gene during development.

Functional analysis of the white + gene of Drosophila by P-factor-mediated transformation

A 12-kb DNA segment spanning the white (w) locus of Drosophila has been inserted into a P-transposon vector and used for P-factor-mediated germ-line transformation. Several red-eyed transformants were recovered which complement the white mutant phenotype. Analysis of the eye pigments and the interaction with the zeste mutation indicates that the w gene inserted at several new chromosomal sites is expressed normally. The tissue-specific accumulation of w transcripts, as studied by in situ hybridization to tissue sections, is the same in transformant and wild-type larvae. This indicates that all the genetic information specified by the w locus is contained within this 12-kb segment of DNA. By secondary mobilization it was shown that the w sequences have been inserted as a functional P(w) transposon which is capable of further transposition.

[Mathematical kinematic methods in joint prosthetics]

By the use of mathematical and cinematical methods a new understanding for the construction as well as for the implantation-techniques for endoprosthesis can be developed. With these methods the size of the natural motion and the process of the natural motion can be studied. So we get better informations about the natural motion and we can deduce criterions for the construction of endoprosthesis, for we can compare the motion of a model with the natural way of motion. So we can estimate preoperative the efficiency and the maximal load of the prosthesis as a result of incorrect motions. Such incorrect motions can be caused or can be avoid by the construction of the endoprosthesis as well as the implantation techniques.

[Diagnosis and surgery of an insulinoma using a glucose-controlled insulin infusion system]

A 71-year-old woman with insulinoma was studied. Preoperatively, using the glucose controlled insulin infusion system (GCIIS) for glucose clamping at various blood glucose levels, autonomous insulin production was demonstrated and intravenous glucose needs for maintenance of normoglycaemia were evaluated. The results of a somatostatin suppression test, guided by the GCIIS, supported the postulation of a well differentiated beta cell adenoma with reduced storage capacity. These assumptions were later confirmed by histochemical and ultrastructural investigations. Hypoglycaemia during surgery was avoided by means of the GCIIS. Upon clamping of the plasma glucose at 90 mg/dl, 15.5 g dextrose had to be given until resection of the tumour. Immediately thereafter, a sharp rise in plasma glucose to 140 mg/dl together with a need for 4.1 U insulin showed that the insulinoma tissue had been removed completely.

[Albescent punctate retinopathy with central pigment epithelium atrophy]

A 45-year-old Italian patient suffering from punctate retinopathy associated with a central atrophy of the retinal pigment epithelium is described. He has suffered from nyctalopia since early childhood, and over the last 3 years has become increasingly susceptible to dazzling. Funktion tests revealed pathologic monofunctional dark adaptation of cones, centrocecal scotoma, a pathologic electro-oculogram and residual a-waves at high light stimulus intensities in the electroretinogram. An autosomal-recessive mode of inheritance is assumed, as 4 of the patient's 9 siblings have the same signs.