Determination of the Avogadro constant by counting the atoms in a 28Si crystal.

The Avogadro constant links the atomic and the macroscopic properties of matter. Since the molar Planck constant is well known via the measurement of the Rydberg constant, it is also closely related to the Planck constant. In addition, its accurate determination is of paramount importance for a definition of the kilogram in terms of a fundamental constant. We describe a new approach for its determination by counting the atoms in 1 kg single-crystal spheres, which are highly enriched with the 28Si isotope. It enabled isotope dilution mass spectroscopy to determine the molar mass of the silicon crystal with unprecedented accuracy. The value obtained, NA = 6.022,140,78(18) × 10(23) mol(-1), is the most accurate input datum for a new definition of the kilogram.

[Comparison of preoperative retinometer values with postoperative visual acuity after surgery of epiretinal membranes]. / Vergleich des präoperativen Retinometerwertes mit dem postoperativen Visus nach Chirurgie epiretinaler Membranen.

BACKGROUND: We report about our clinical experience when comparing the preoperative retinometer values with the postoperative visual acuity after microsurgical excision of epiretinal membranes (ERM). PATIENTS AND METHODS: Pars plana vitrectomy with membrane peeling was performed in 56 eyes of 53 patients. Preoperatively, we obtained the distant and near visual acuity and the retinometer value. Postoperatively, we compared the preoperative retinometer value to the best postoperative visual acuity. RESULTS: The preoperative retinometer value was in 39 eyes (70 %) equal to the best postoperative distant visual acuity (+/- 1 line) and in 34 eyes (61 %) equal to the best near visual acuity (+/- 1 line). A difference of + 2 or - 2 lines or more from the retinometer value was found in 17 eyes (30 %) for the best postoperative distant visual acuity and in 22 eyes (39 %) for the best near visual acuity. 49 eyes (87.5 %) had a better visual acuity after pars plana vitrectomy, 6 eyes (10.7 %) had equal visual acuities and one eye (1,8 %) was worse than the preoperative visual acuity. The average improvement of vision after the operation was + 2.5 lines for the distant and + 2.4 lines for the near visual acuity. CONCLUSIONS: The preoperative retinometer examination is a precise method for obtaining the visual acuity of patients selected for pars plana vitrectomy with membrane peeling. Uncertain results can be achieved in eyes with very opaque ERM and ERM with macular edema.

[Correlation between inpatient and ambulatory psychotherapy from the viewpoint of the family physician]. / Verbindungswege zwischen stationärer und ambulanter Psychotherapie aus hausärztlicher Sicht.

Very often the position of the family doctor is being reduced to a mere "doorkeeper" (a person who just lets the patients in and out). He should, however, be the first person being addressed also by patients with psychic and psychosomatic problems, which requires a fundamental education in psychosomatic or psychotherapeutic medicine. Compared to specialists or doctors working in hospitals the advantage of a family doctor is that the patients already trust him, and, furthermore, he is familiar with the family background. He functions as interpreter of the patients' complaints, and--given a certain indication--he combines medication and psychotherapy, which are the two essential parts of psychotherapy being carried out by a doctor. If the symptoms exceed his competence, he must send the patient to a specialist who can cope with his problems. His personal advice is essential in such a case. After having been released from stationary medical treatment, the patient should have the possibility to consult his family doctor again for the sake of continuous medical treatment. A successful combination of stationary and out-patient psychotherapy can be negatively influenced by the following facts: devaluation of the family doctor's competence by specialists or offending of the family doctor's feelings of self-reliance because of a supposed failure.

[Test performance with minimal alcoholic intoxication]. / Testleistungen bei Minderalkoholisierung.

Driving ability of 34 males under minor influence of alcohol was tested at the ART 90 test unit of the Austrian Road Safety Board. Furthermore, 22 males not under the influence of alcohol, formed part of the sober control group. Some months previously, all volunteers had completed a driver aptitude test consisting of identical tests for all participants. Therefore a before-and-after analysis as well as a comparison of the different groups could be carried out by means of MANOVA. A high motivational level was guaranteed in the first tests as all test persons' driver qualification depended on the results of their driver aptitude tests. Months later they were invited to participate in this study on a voluntary basis. The second tests took place immediately after a social evening at which 8 volunteers were present at any one time. To create conditions as near to reality as possible, only alcohol that would be readily available to the public was served. An entertainer ensured an equally cheerful and relaxed atmosphere in both the experimental and control groups. Alcohol levels were measured by means of the Siemens breathalyser. Results show that as early as an average alcohol level of 0.67/1000 performance is significantly impaired: three times more errors in concentration tests, twice as many errors in reaction tests, twice as many observation errors in visual structuring and a considerable reduction of reactive stress tolerance. On the other hand quantitative dimensions of performance such as reaction time are not significantly impaired. In addition, the readiness to take risks increases with alcohol consumption as is shown by means of questionnaire.

Different mechanisms underly shifting set on external and internal cues in Parkinson's disease.

A set shifting task consisting of the comparison of two digits according to their numerical value or their form guided by an explicit (external cue) or implicit (internal cue) rule was performed by 8 untreated and 19 treated patients suffering from Parkinson's disease (PD) and 15 control subjects. The subjects could not predict the number of trials for a given target. The treated PD patient group exhibited increased post-shift error rates under the internal cue condition. In the external cue condition, only the untreated patients produced more errors when shifting to a new response criterion. Reaction times were prolonged in treated PD patients, irrespective of type of cue. Large interindividual variability within the patient groups is considered as meaningful and indicates individual differences in the neuropsychological impairment and/or the neurotransmission deficit. Pathophysiological and neuropsychological impairments underlying these findings are discussed on the basis of the models of Penney and Young (1983/1986) and Norman and Shallice (1980/1986).

[Chandler syndrome--a case report]. / Das Chandler-Syndrom--eine Falldemonstration.

Chandler's syndrome is a particularly rare form of unilateral secondary glaucoma, in which--besides other symptoms--corneal epithelial edema occurs even when intraocular pressure rises slightly to above 20 mmHg. For 3 years now the authors have had a patient under observation whose condition corresponds to Chandler's syndrome. A remarkable feature of this case is that corneal edema occurred at physiological pressure levels. The symptoms and course are described; a brief differential diagnostic review is given and therapeutic possibilities are pointed out.

[A follow-up study of combined cataract/trabeculectomy operation]. / Nachuntersuchung bei kombinierter Katarakt-Trabekulektomieoperation.

In the past 12 years 69 combined trabeculectomy/cataract operations have been performed at Graz University Eye Clinic. Of these, 33 were examined after an average interval of three years. In 23 cases intraocular pressure was regulated without therapy, and four eyes were regulated with additional therapy. In five eyes no satisfactory pressure could be reached and one eye was lost due to late infection. In ten cases a hyphema appeared; in seven cases registered a rise in intraocular pressure was recorded and in two cases a flat chamber. In view of the great variety of indications this method seems to be especially suitable for elderly patients.

[A case of papillophlebitis]. / Ein Fall von Papillophlebitis.

A case history of a young man with recurrent papillophlebitis. The fluorescein angiogram showed an extensive hyperfluorescence of the disk and surrounding retinal veins in the venous and late phase. The electro-ophthalmological findings were normal in both eyes, while computerized perimetry demonstrated an enlarged blind spot in the bad eye but was normal in the other. The paper concludes with a description of the differential diagnosis of papillophlebitis, papillitis and papilledema caused by vascular occlusive disease or increased intracranial pressure.

[Light and electron microscopy results following photocoagulation of ciliary processes with argon lasers]. / Licht- und elektronenmikroskopische Ergebnisse nach Photokoagulation der Ziliarkörperzotten mit dem Argonlaser.

The authors' own clinical observations have shown that a pressure-lowering effect in secondary glaucomas resistant to therapy can be obtained by photocoagulation of the pars plicata of the ciliary body using an argon laser. In order to be able to estimate the damaging effect of photocoagulation and thus to be able to administer it in a sensible dose, the authors applied this technique to four patients with tumorous eyes that had to be enucleated, with a subsequent histological and electron-microscopical scrutiny. The laser energy was varied from 750 to 2000 mW at a constant exposure time of 0.2 s and a dot size of 100 micrograms. With clear-refracting media an energy of 1000 mW brought about coagulative effects without any substantial side-effects. Damage was then generally restricted to the aqueous humorproducing formation, i.e., the ciliary epithelium and the adjacent stromal part.

[Assessment of lesions in various sections of the visual pathway]. / Die Beurteilung von Läsionen im Sehbahnbereich.

The suitability of ultrasonography, computer tomography and Octopus perimetry is illustrated with reference to an investigation carried out in 60 patients. First, the characteristic symptoms are described, depending on the localization of the lesion in the visual pathway. Then the advantages and disadvantages of the various examination methods are compared. In the orbita, echography is the most accurate method in the anterior segments, while the balance shifts increasingly in favor of CT toward the retrobulbar region. As far as intracranial tumors are concerned, there is good correlation between CT and VF findings in the case of sellar processes and pathologic changes of the midline and occipital lobe. In the frontotemporal region, on the other hand, VF defects are found in only one-half of the cases, while in the case of vascular lesions there is no apparent correlation between perimetry findings and the size of the lesion demonstrated on the computer tomogram. The importance of the Octopus for early recognition of such lesions is discussed.

[Surgical method for the treatment of irreversible angle-closure glaucoma and aphakic glaucoma. Direct ciliary body coagulation with partial cyclodialysis]. / Operationsmethode zur Behandlung des irreversiblen Winkelblockglaukoms und des Aphakieglaukoms. Direkte Ziliarkörperkoagulation mit partieller Zyklodialyse.

Among 16 patients aged from 31 to 86 there were 13 cases of hemorrhagic glaucoma, three cases of secondary glaucoma from iritis and one case of secondary angle-closure glaucoma after trauma. Reduction in intraocular pressure was achieved by a surgical method which primarily aims to improve the outflow of aqueous humor. The ciliary body is laid bare by preparation of a scleral flap, a partial cyclodialysis is attached on both sides and the ciliary body is induced to stricture by coagulation, so that a large enough cleft is created. Before the operation, pressure ranged from 34 to 64 mm Hg; after the operation, during postoperative periods of observation lasting from two to 32 months, there were 14 cases in which the pressure was below 25 mm Hg and two cases with 30-40 mm Hg respectively. In view of the good results and the few complications, this method of operation can be recommended for treatment of both irreversible angle-closure glaucoma and aphakic glaucoma.

The effects of visual field changes and ocular hypertension on the visual evoked potential.

The effects of visual field changes and ocular hypertension on visual evoked potentials were investigated by photopic ERG and by luminance and pattern-reversal EPs on 116 glaucomatous and on 7 normal eyes. The problem was approached by way of four investigations: Firstly, which nerve structures are affected by glaucoma and how do visual field defects caused by glaucoma influence the EP? The results show a functional diminution of all intraocular nerve structures in which the prelaminary part of the optic nerve is most affected. The EPs, especially the pattern-reversal EPs, are markedly diminished if the visual field defects extend inside the 10 degree boundary. Differences in the visual field defects of both eyes and the course of the sickness can be well observed by the EPs. Secondly, which preoperative prognosis for visual acuity produced by the EP can be given to patients who have a dense cataract in addition to glaucoma? A postoperative improvement of the visual acuity can be expected if the L-EPs are within the standard deviation. If the EP is distinctly diminished and does not increase with increasing stimulus intensity, then there is no hope for an improvement of the visual acuity after the operation. Thirdly, does a decrease of intraocular pressure in chronic and acute glaucoma influence the EP? In acute glaucoma with pressure levels of 50 mmHg or more, and sometimes in chronic glaucoma with pressure levels of about 30 mmHg, an increase of the amplitude of the EP and an improvement of the visual field could be noticed after pressure regulation. Fourthly, what is the behaviour of the EP in normal and glaucomatous eyes at experimentally elevated intraocular pressure? The amplitudes of the ERG components show a gradual decrease in normal as well as in glaucomatous eyes when intraocular pressure is increased and are maintained when intraocular pressure reaches systolic ophthalmic blood pressure. On the other hand, the EPs show a strong decrease in amplitude when intraocular pressure exceeds the mean ophthalmic blood pressure, particularly in the case of glaucomatous eyes.

[Diagnosis of space-occupying renal processes: sonography and aimed fine-needle biopsy]. / Diagnostik raumfordernder renaler Prozesse: Sonographie und gezielte Feinnadel-Biopsie.

It is reported on 3 cases in which by sonographic examination a tumorous process could be established. In all cases the additional investigation by fine needle biopsy and cytological examination proved the presence of malignant cells. This local renal process proved by sonography could be verified neither by i.v. pyelographic nor arteriographic methods. For two patients the diagnosis based on sonography, fine needle puncture and cytological test could be verified by operation. The third patient was not operated in spite of malignant cells in the cytogram because of negative computer tomography provided by an external hospital.

[Oncocytoma of the thyroid gland]. / Das Onkozytom der Schilddrüse.

The Huerthle cell tumor is quite frequent in southern Germany; this is shown by examinations of patients from our field hospital for nuclear medicine. Our findings conclude with data presented by Galvan (Salzburg). The certainly quite short observation period shows that Huerthle cell adenomas occur much more frequent than carcinomas, when a Huerthle cell neoplasm is diagnosed cytologically. Our investigations show, that Huerthle cell tumors of the thyroid gland are a not wellknown and rare disease, which necessitates a clear decision as result of the cytological finding as far as necessary surgical measures are concerned. This is probably the only way to improve the efficiency of measures for early diagnosis and treatment of tumors of the thyroid gland. Considering the want of clearness which still exists referring to the dignity of Huerthle cell tumors in our opinion even cases which had been diagnosed as adenomas histologically should be controlled regularly once a year during an observation period of ten years.

[Sjögren's reticular pigmentary dystrophy (author's transl)]. / Die retikuläre Pigmentdystrophie nach Sjögren.

An examination of two families with reticular pigmentary dystrophy of the retina is reported, and typical findings are reviewed. Visual actuity, visual fields, dark adaptation and color vision were normal; the photopic ERG was normal or subnormal, while the scotopic ERG was normal. Only the EOG findings were pathologic in all of the subjects examined. A description of the various forms of reticular dystrophy and of its differential diagnosis is followed by a discussion concerning the classification of all varieties of this disease as patterned dystrophies of the pigment epithelium.