Jonas S. Friedenwald

A histochemical method for localizing cholinesterase activity.

Summary A histochemical method is presented for localizing ChE activity by incubating tissue sections in a medium containing acetylthiocholine, copper glycinate and copper thiocholine. Results obtained with several tissues containing specific ChE are described and illustrated.

Notes on the Allergy Theory of Sympathetic Ophthalmia

This study was undertaken with the aim of discovering whether the histologic findings in sympathetic ophthalmia were compatible with the allergy theory of this disease. The relation of melanin granules to the specific histologic features of the inflammation in the uveal tracts, retina, and skin revealed that allergy to uveal pigment is an adequate explanation of these characteristics. However, allergy to uveal pigment may be present without sympathetic ophthalmia. If the allergy theory is correct some additional factor other than allergy is, therefore, necessary to initiate the disease. A study of the Dalen nodules sometimes found in sympathetic ophthalmia suggests that the additional factor may be a proliferation of the melanophores. The results of some preliminary experiments based on this hypothesis are reported. From the Wilmer Ophthalmological Institute of the Johns Hopkins University and Hospital. Read before the Association for Research in Ophthalmology, in Cleveland, June 12, 1934.

Xanthurenic Acid∗ Excretion Studies in Diabetics With and Without Retinopathy.†

Conclusions and Summary 1. Diabetic patients with and without retinopathy excrete on the average significantly greater quantities of xanthurenic acid after an oral test load of 10 g dl-tryptophane than do non-diabetic controls. 2. There is no significant difference in the xanthurenic acid output of diabetic patients who have, and those who have not developed retinopathy.

Retinal Vascular Dynamics

An analysis is presented of some of the physical factors which are required to explain functional changes in the caliber and tortuosity of the retinal blood vessels. The role of these factors in various types of circulatory diseases is discussed. From the Wilmer Ophthalmological Institute of the Johns Hopkins University and Hospital.

The two alkaline phosphatases for glycerophosphate in the rat's kidney

Abstract Evidence has been presented from in vitro studies, in confirmation of histochemical findings, that there exist, in the kidney of the rat, two distinguishable phosphatases capable of hydrolyzing sodium β-glycerophosphate in an alkaline environment. One of the enzymes, A, has been shown to be inhibited by iodoacetate and to be activated by glycine and zinc. The other, B, which is not inhibited by iodoacetate, is activated by magnesium and inhibited by glycine, and by those concentrations of zinc which activate the A enzyme. Some of the dissociation constants for the two enzymes with substrate, activators, and inhibitors have been calculated. The reciprocity of the effects of amino acids and bivalent metals on the two enzymes, has been interpreted in terms of glycine cation complex formation.

THE ACTION ON NITROGEN MUSTARDS AND RELATED SUBSTANCES ON CELL DIVISION

Some analogues that possess similar biological and chemical reactivities are shown in FIGURES 2 and 3. The latter is the general formula for the nitrogen mustards. Substances of this type have proved particularly useful in biological experimentation since, by varying the group R, it is possible to vary the physico-chemical characteristics of the molecule and thus obtain an extended group of substances which vary somewhat in their penetrating power, reactions, rates, etc. Much of the current work is based on the hope that, by a suitable variation in the R group, substances will be obtained that have a higher degree of biological selectivity than the simplest compounds in this series. The chemical formula of mustard gas is shown in FIGURE 1.

The adrenochrome redox system

Abstract 1. 1. Polarographic recordings of 0.001 M solutions of adrenochrome at 3 °C. taken before, during, and after reduction with hydrogenplatinized asbestos over a pH range of 5.61–8.08 indicated that under these conditions a two-electron reversible reduction occurs with a low order of semiquinone formation. In confirmation of previous studies, the reductant was found to be fairly stable above pH 7.0. 2. 2. Measurements of hydrogen uptake by solutions of adrenochrome, prepared by both the iodine and silver oxide oxidation methods, in which reduction was catalyzed by both platinized asbestos and palladinized barium sulfate under the same approximate conditions of temperature, concentration, and pH as above, showed an initial rapid consumption of two atoms of hydrogen per molecule of adrenochrome. The same result was obtained with the similar red compound prepared by the oxidation of epinine. 3. 3. The present results are in agreement with the structures of the adrenochrome redox system originally proposed by Green and Richter. Discordant reports in the current literature are discussed and possible reasons for the discrepancies suggested.

A new astigmatic chart

Abstract A new astigmatic chart which the writer has found useful is described, and the theoretic considerations which determine the scope and degree of its usefulness are discussed.

PITFALLS IN HISTOCHEMISTRY: AN UNSUCCESSFUL ATTEMPT TO DEMONSTRATE MUCOID SULFATASE ACTIVITY IN MAMMALIAN TISSUE

Attempts to demonstrate a sulfatase in mammalian tissues attacking sulfated mucopolysaccharides were unsuccessful. Both chemical and histochemical methods were employed. Some risks involved in the use of the lead salt technique in enzyme histochemistry are pointed out.

Freely Movable Instrument for Ophthalmoscopy with Yellow Green Light

Abstract An arc lamp is so mounted on the brackets as to be freely movable in all directions. Attached to the front is the support for a flat faced bottle in which a solution of anilin green naphthol is used as the light filter. The light obtained is relatively monochromatic so that the effect of the chromatic error of the eye is removed and an ophthalmoscopic picture of great distinctness is obtained. From the Department of Pathology, Johns Hopkins University.