PubMed Health⌕ Search

Biomedical subjects

I F Norstrand

Publications and source records attributed to I F Norstrand.

At least 19 recordsLinked to original sources
PubMed1985

Histochemical demonstration of adenosine deaminase in the human neuraxis. Preliminary observations.

Because of the importance of adenosine deaminase (ADA) in brain function, a histochemical method for visualizing the enzyme in various areas of the human neuraxis was devised, using an MTT [3-(4,5-dimethyl-thiazolyl-2)-2,5-diphenyltetrazolium bromide] method and glutaraldehyde fixation. Controls consisted of preincubation without the substrate, incubation with omission successively of the substrate, MTT tetrazolium, purine nucleoside phosphorylase (PNP), xanthine oxidase (XO), NaCl, boiling for 20 min prior to fixation and incubation, and of incubation of sections with two powerful inhibitors of the enzyme, i.e., 2'-deoxycoformycin and EHNA [erythro-9-(2-hydroxy-3-nonyl)adenine.HCl]. The positive reaction consisted of the deposition of brownish-purple granules, as well as a diffuse nongranular reaction in the cytoplasm of neurons and glial cells, and in the interstitial spaces. Sections from 15 different areas in four brains were examined by this method. This is the first time that adenosine deaminase has been demonstrated histochemically in the nervous system of humans or of any other species.

Adenosine Deaminase↗
PubMed1985

A molecular hypothesis concerning the pathogenesis of myasthenia gravis.

The purine enzyme, adenosine deaminase, is essential for the maturation of lymphocytes, cell growth and normal immune function. Since adenosine deaminase has the highest activity in the thymus and in T lymphocytes, it is hypothesized that a defective or altered enzyme may be a cause of myasthenia gravis, a lymphoid dyscrasia. It is proposed that the alteration is on the non-catalytic portion of adenosine deaminase concerned with the normal immune function of T lymphocytes. Lymphocytes, particularly suppressor T lymphocytes containing a defective adenosine deaminase will function improperly. They will lose their normal immune regulatory function, allowing immunoglobulin-producing B lymphocytes to produce autoantibodies against the nicotinic acetylcholine receptor, with resultant induction and perpetuation of the autoimmune state. In an attempt to compensate for the defect, there may be hypertrophy of the thymus and lymphoid system, with overproduction of a defective adenosine deaminase. Since many of the functions of thymosin, the alleged active principle in thymus are identical to those of adenosine deaminase, it is postulated that thymosin may be a subunit of adenosine deaminase.

Adenosine Deaminase↗
PubMed1984

Regional distribution of adenosine deaminase in the human neuraxis.

Adenosine deaminase was determined in 28 different areas of the human neuraxis in 5 adult male cadavers, with no known disease of the nervous system, using a very sensitive colorimetric method. The enzyme was highest in the frontal lobe white matter, and lowest in the medulla and all levels of the spinal cord. Enzyme content was about twice as great in the white matter of the frontal and temporal lobes and cerebellum as it was in the cortical gray matter of these areas, but only slightly higher in the white matter of the parietal and occipital lobes as compared to gray. Average values of the enzyme were found in the remaining areas of the brain, with the exception of the pons and cerebellar white matter, where a higher than average value was noted.

Adenosine Deaminase↗
PubMed1983

Effect of inhibition of purine enzymes on benzodiazepine binding in the human brain.

Since inosine is an inhibitory ligand for benzodiazepine binding, and since several of the purine enzymes have a specific localization, it was hypothesized that the unique distribution of benzodiazepine receptors may be dependent on the regional concentrations and specific actions of these enzymes in increasing or decreasing the amount of inosine. To test the above theory, the binding of 3H-flunitrazepam to receptors was studied on homogenates of various regions of autopsied human brain before and after treatment with irreversible potent inhibitors of the purine enzymes guanine deaminase and adenosine deaminase. As predicted, inhibition of guanase, which metabolizes guanine and hypoxanthine to xanthine, caused a marked inhibition of binding in the cerebral cortex and midbrain, where there is an abundance of enzyme, and only slight change in binding in the medulla, cerebellum or pons, where there is little enzyme. When adenosine deaminase, which converts adenosine to inosine, was inhibited, there was increased binding, with as much as a 4-fold increase in the frontal lobe, and very little effect in the cerebellum, medulla or temporal lobe.

Adenine↗
PubMed1982

Cerebral disorders detected by EEG and missed by CAT scan.

EEG recordings of the electrical seizure activity during unilateral non-dominant (right) hemisphere electroconvulsive therapy reveal three phases of activity: (1) Phase I initial 14-22 Hz rhythmic activity; (2) Phase II arhythmic polyspike activity; and (3) Phase III rhythmic 2 1/2-3 1/2 Hz. spike/polyspike-wave activity. The Phase II polyspike activity appears as an orderly march beginning in the right anterial temporal area. The Phase II activity is of higher voltage on the right side compared to the left side. The Phase III activity ends abruptly with a nearly isoelectric tracing (the "fit switch").

Brain Diseases↗
PubMed1980

Topographical distribution of purine nucleoside phosphorylase in the human neuraxis.

The activity of purine nucleoside phosphorylase was determined at various levels of the human neuraxis in 5 brains and 2 spinal cords, using the method of Lewis and Glantz. The determination is based on the decrease in optical density of guanosine at 252 nm and 40 degrees C, with conversion of this compound to guanine and ribose-1-phosphate by phosphorolysis. Our studies show a fairly uniform distribution of the enzyme in the human CNS, with an average value of 209 mumol of guanosine transformed/min/g of wet tissue. The lowest values are found in the spinal cord and cerebellar grey matter, and highest amounts in the occipital grey and white substance.

Adult↗