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Biomedical subjects

J Reiner

Publications and source records attributed to J Reiner.

At least 37 records · Page 2Linked to original sources

[Possibilities for reproducing stereoscopic images on monitors in relation to the surgical microscope].

A variety of systems, including open-sight systems, can be used in combination with an operating microscope to reproduce stereoscopic images on a monitor. All these systems have the disadvantage that they disturb the free interplay of accommodation and convergence, and in the long term this can be tiring for the observer. A method similar to holography might be an ideal open-sight method for imaging the surgical procedure three-dimensionally.

Equipment Design↗

[Evaluation of intraocular lenses].

With an optical spherometer and a collimator it is possible to determine the curvature radii, focal length, and vertex power of IOLs. For testing image quality, optotype charts of the kind familiar to ophthalmologists should be used, and the images produced by the IOLs in air or water observed with a microscope. Bicofal intraocular lenses should always be tested in a solution in planoparallel cuvettes or artificial eyes. The imaging characteristics of different lenses can be demonstrated using a telescope with 1 x magnification.

Humans↗

[Eyeglasses].

Spectacles belong to the most ancient inventions in cultural history. Their development, however, cannot be regarded as final. New impetus has resulted in the creation of non-spherical lenses and, through the development of refractive lenses, in a more progressive optic effort.

Eyeglasses↗

An Assessment of the Rubisco Inhibitor: 2-Carboxyarabinitol-1-Phosphate and d-Hamamelonic Acid 2-Phosphate Are Identical Compounds.

2-Carboxyarabinitol-1-phosphate, the nocturnal inhibitor of ribulose-1,5-bisphosphate carboxylase/oxygenase is identical with d-hamamelonic acid-2(1)-phosphate. Reasoning is based on theoretical considerations as well as on mass spectra and (1)H- and (13)C-NMR spectra of the phosphate-free compounds. d-Hamamelonic acid-2(1)-phosphate is interpreted as a metabolic derivative of d-hamamelose-2(1),5-bisphosphate which originates in the chloroplast from fructose-1,6-bisphosphate. A simple method for the synthesis of the inhibitor is suggested.

Journal Article↗

Immunocytochemical evidence of molecular photoreceptor markers in cerebellar medulloblastomas.

With the use of antisera against bovine retinal S-antigen and bovine opsin the authors demonstrate that in cerebellar medulloblastomas certain tumor cells display immunocytochemical properties characteristic of retinal photoreceptors and pinealocytes. S-antigen-like and opsin-like immunoreactions occur in nine of 28 medulloblastomas investigated. All tumors displaying S-antigen-like immunoreactive neoplastic cells also contain opsin-like immunoreactive cells; however, the opsin-like immunoreactive cells were less frequent than the S-antigen-like immunoreactive cells throughout all positive cases. The immunoreactive cells displayed several long processes. Generally, both S-antigen and opsin-like immunoreactive cells considerably vary in number among individual tumors. The results indicate that certain neoplastic cells of medulloblastoma are capable of expression of photoreceptor-specific proteins and, thus, may be closely related to tumor cells of retinoblastoma and pineocytomas previously shown to bind antisera against retinal S-antigen and opsin. No S-antigen and opsin-like immunoreaction was found in malignant teratomas and germinomas of the pineal gland, oat cell tumors, astrocytomas, ependymomas, oligodendrogliomas, glioblastomas, gangliogliomas, gangliocytoma, ganglioneuroblastomas, neuroblastomas, and esthesioneuroblastoma.

Cerebellar Neoplasms↗

A stereoscopic diagonal inverter (SDI) for wide-angle vitreous surgery.

All known methods of wide-angle observation of the fundus deliver an inverted image. To overcome these difficulties a stereoscopic diagonal inverter (SDI) was developed, which serves as an accessory to the operating microscope. This device permits the microscopic image to be vertically inverted and laterally reversed, while retaining full stereopsis, and thus makes wide-angle observation devices such as the Rodenstock Panfundoscope contact lens (150 degrees) and a modified version of the binocular indirect ophthalmoscope (70 degrees-90 degrees) usable in vitreous microsurgery.

Humans↗

[Optics of surgical microscopes].

Operating microscopes are binocular telescopic magnifying glasses which have been extended by afocal systems. The important feature of these instruments is that the magnification can be changed rapidly. The way the pancreatic magnification changer works can be described very simply as a synthesis of two Galilean telescopes. Operating microscopes can also be used as binocular ophthalmoscopes.

Eye Diseases↗

[Free-vision refraction determination].

A refraction process is called free vision if the patient's visual field is not restricted at all, or at most by the same amount as when using normal spectacles. Free-vision refraction measurement is performed with the help of virtual lenses, which are real optical images of material lenses. In certain circumstances virtual lenses act as normal optical lenses. The advantage of free-vision refraction measurement lies above all in the fact that remote refraction measurement can also be performed from a distance of less than five meters. Moreover, it permits over-refraction, which enables the duration of the measuring procedure to be shortened considerably.

Eyeglasses↗

[Derivation and critical analysis of formulas for the calculation of the refractive power of intraocular lenses].

Using matrices, formulae are derived for calculating the refractive power of the ocular system and of intraocular lenses. These formulae take into account the finite extension of the lenses under consideration. They also contain only measurable quantities. Some sources of uncertainty in predicting the power of the IOLs are pointed out estimates of their orders of magnitude are given. By combining the new results with those obtained on the basis of regression analysis, the prediction of IOL power can be improved, especially for eyes with short axial length. In a critical comparison with formulae which are well known from the literature, a number of them were found to be incorrect. In conclusion, some suggestions are made for improving the prediction of lens power.

Humans↗

Profiles of strongly polar and less polar acids obtained from human blood, plasma and serum by two-step ultrafiltration.

A two-step ultrafiltration method combined with anion-exchange chromatography is described for the separation of lipophilic and strongly lipophobic acids occurring in human blood, serum and plasma. After treatment with diazomethane, the acid fractions are separated further by gas chromatography. The acids were identified by their mass spectra. Profiles obtained from the strongly acidic fraction of blood samples of healthy individuals are characterized by main peaks corresponding to organic phosphoric acid esters. The peaks are absent in plasma and serum.

Acids↗

[A variable cross cylinder with extended scale].

The graduation of the scale on the Stoke's Cylinder lens can be influenced by using an additional spherocylindrical lens for improved readability of lower-strength corrections. Furthermore, it is possible to spread the scale graduation to show a double-angle marking, again by using an appropriate spherocylindrical combination.

Calibration↗

On the conformation of 5-substituted uridines as studied by proton magnetic resonance.

The proton magnetic resonance (pmr) spectra of 10 basemodified uridine derivatives x5Urd have been measured at 3 degrees, 30 degrees, and 60 degrees C in order to correlate the electronic effects of different substituents with the molecular conformation of the respective nucleosides. The results presented demonstrate the close relation between conformational parameters and the electron-affinity of the substituents as reflected by their Hammett constants. Going from electron-donating to electron-accepting groups, the portion of N-conformer in the ribose N in equilibrium S equilibrium increases from 44% to about 90%. In addition the percentage of gauche-gauche rotamer as measured for the exocyclic groups changes from about 30% in nh52Urd to more than 80% in no52Urd.

Magnetic Resonance Spectroscopy↗

Co-occurrence of immunoreactive corticotropin-like and alpha-melanotropin-like material in pituitary cells: differences between young and adult rats.

We examined to which extent adrenocorticotropin (ACTH)-like substances are cleavable into alpha-melanotropin (MSH)-like material by application of exogenous enzymes on pituitary sections prior to immunocytochemical stainings. In pro-opiomelanocortin (POMC) cells of the anterior lobe from developing rats (1 to 21 postnatal days) at least one of two cells contained alpha-MSH-like immunoreactivity besides ACTH-like immunostaining. Pretreatment of these tissue sections with tryptic enzymes enhanced remarkably alpha-MSH-like immunostaining. In contrast, alpha-MSH-like immunoreactivity was almost not detectable in anterior lobes from adult rats, also after treatment with enzymes. After adrenalectomy (ax) POMC cells in anterior lobes behaved similarly: a few days after the operation almost all ACTH cells contained also alpha-MSH immunostaining, whereas after more than two weeks alpha-MSH immunostaining was nearly absent, also after application of enzymes. In contrast to rats, in young and adult guinea pig pituitaries all ACTH-like immunoreactivity was prevented by treatment with tryptic enzymes. These observations are consistent with the assumption that occurrence of ACTH- and alpha-MSH-like substances in rat pituitaries is regulated by a protection mechanism against proteolytic cleavage in the ACTH sequence which appears with delay in differentiating and maturing cells.

Adrenocorticotropic Hormone↗

[A reading aid for the visually handicapped].

A new reading aid for the visually handicapped is described. It consists of a normal pair of fieldglasses and a mirror system, and can be used either monocularly or binocularly. It features an unusually long working distance of 210 mm, regardless of magnification.

Aged↗