>Posted-Date: Mon, 13 May 1996 15:20:09 -0700
>Date: Mon, 13 May 1996 15:19:34 -0700 (PDT)
>From: Camilla Cracchiolo <[log in to unmask]>
>To: "Ronald F. Vetter" <[log in to unmask]>
>Subject: Re: Ag+ and blood/brain barrier (fwd)
Here are some abstracts passed on to me. You might find them interesting.
I, Ron, thank: Camilla Cracchiolo, RN [log in to unmask]
Here are reports of two women with argyria (silver poisoning) with
demonstrable silver in the CNS. Silver crosses the BBB in rodents and is
apparently neurotoxic. These references indicate that humans are probably
no different. Prior to modern antibiotics, silver (as well as other heavy
metals like arsenic and mercury) were used as antimicrobials. Perhaps the
older literature has some discussions of the neurotoxicity of silver
treatments.
Dietl HW. Anzil AP. Mehraein P. Brain involvement in generalized
argyria. Clinical Neuropathology. 3(1):32-6, 1984 Jan-Feb.
Abstract
Cutaneous argyria was diagnosed in a 59-year-old woman. Manic depressive
psychosis developed at about the same or a short time thereafter. The
patient died 6 years later from a ruptured aortic aneurysm. At autopsy
silver deposits were seen in skin, mucous membranes, heart, kidney, and
liver. In the central nervous system the leptomeninges and choroid
plexuses contained silver granules. In addition, silver granules were
visualized in the walls of many intraparenchymal vessels, particularly of
the basal ganglia, hypothalamus, substantia nigra, and cerebellum.
Progressive glial changes and cellular gliosis were evident in many areas
of the brain. With the electron microscope the deposition of silver
granules in basal membrane structures of the choroid plexus and
intracerebral vasculature was amply confirmed. Furthermore, silver
deposition was seen in brain parenchymal cells inside bodies of apparently
lysosomal nature. The silver content of various brain regions was
determined by absorption spectrophotometry.
Landas S. Fischer J. Wilkin LD. Mitchell LD. Johnson AK. Turner JW.
Theriac M. Moore KC. Demonstration of regional blood-brain barrier
permeability in human brain. Neuroscience Letters. 57(3):251-6, 1985 Jun
24.
Abstract
The brain of a 78-year-old woman with argyria was examined at autopsy.
Silver nitrate deposition was observed in circumventricular organs (CVO)
and in the paraventricular and supraoptic nuclei of the hypothalamus.
These findings parallel animal experiments of other investigators and are
the best demonstration so far of regional absence of the blood-brain
barrier in humans. These observations demonstrate similarities between
humans and other mammals of CVO anatomy, permeability to blood-borne
agents, and perhaps neural connections between CVOs and magnocellular
nuclei.
Rungby J. Slomianka L. Danscher G. Andersen AH. West MJ. A
quantitative evaluation of the neurotoxic effect of silver on the volumes
of the components of the developing rat hippocampus. Toxicology.
43(3):261-8, 1987 Mar.
Abstract
The volumes of the components of the hippocampus of rats subjected to
subcutaneous injections of silver during the first 4 postnatal weeks were
compared to those of littermate controls. Of the 14 components measured,
only the pyramidal cell layer was found to be significantly smaller in the
treated animals. These findings indicate that the perikaria of the
pyramidal cells are either the first elements in the developing
hippocampus to show signs of silver toxicity or that they are the
selective sites of silver neurotoxicity. The volumetric approach is shown
to be a sensitive means by which small localized neurotoxic effects can be
detected.
Rungby J. Danscher G. Hypoactivity in silver exposed mice. Acta
Pharmacologica et Toxicologica. 55(5):398-401, 1984 Nov.
Abstract
The functional implications of the presence of silver in the central
nervous system are unknown. Since silver is present in the environment and
since systemic silver poisoning leads to intraneuronal accumulations of
the metal we have evaluated the possible effects of silver on the open
field behaviour of mice. Argyric mice have been compared with controls in
three experiments, one including long term administration of 0.015% silver
nitrate in the drinking water and two in which the reactions of male and
female mice to shock doses of silver lactate have been studied. In all
experiments the silver treated mice were hypoactive. We suggest that this
hypoactivity is due to an influence of silver upon the functional status
of the CNS.
Rungby J. Danscher G. Localization of exogenous silver in brain and
spinal cord of silver exposed rats. Acta Neuropathologica. 60(1-2):92-8,
1983.
Abstract
Exogenous silver in brain and spinal cord sections from rats treated with
Protargol, silver lactate or silver nitrate was visualized by physical
development. The silver penetrated the blood-brain barrier and accumulated
in neurones and glia. The distribution of silver in the CNS was
heterogeneous. Even with low doses and short survival periods, silver was
found to accumulate in large motoneurones in the brain stem and spinal
cord and neurones in the cerebellar nuclei. Silver was only found in di-
and telencephalic structures after extensive exposure. Silver distribution
following oral silver lactate and silver nitrate treatment differed in
that silver nitrate resulted in a relatively high content of silver in
glia whereas deposition occurred preferentially in neurones following
silver lactate treatment. Electron-microscopical studies showed that
silver was located intracellularly in the lysosomes and extracellularly in
basement membranes and elastic fibres of the vessels.
Danscher G. Stoltenberg M. Juhl S. How to detect gold, silver and
mercury in human brain and other tissues by autometallographic silver
amplification. Neuropathology & Applied Neurobiology. 20(5):454-67, 1994
Oct.
ron 1936, dz PD 1984
Ronald F. Vetter <[log in to unmask]>
http://www1.ridgecrest.ca.us/~rfvetter/
