Shiro Sumiyoshi

Experimental organic mercury poisoning — Pathological changes in peripheral nerves

SummaryOrganic mercury firstly affects peripheral nerves all over the nervous system. In peripheral nerves, pathological changes are selectively observed in sensory nerve fibres and are as follows: Swelling and degeneration of Schwann cells, noticeable changes in both myelin sheaths and axons. Proliferating cells such as Schwann cells and macrophages may be acting the role of removal and digestion of degenerated myelin and axon. The pathological changes in myelinated fibres tend to begin at the nodes of Ranvier. With the quantity of organic mercury which was administered, only peripheral nerves were injured. From this point of view, we speculate that, of the neurological signs, only sensory disturbance might be found in some of the patients poisoned by organic mercury.ZusammenfassungOrganische Quecksilberverbindungen schädigen im Nervensystem zunächst die peripheren Nerven. Dabei werden die sensiblen Fasern bevorzugt betroffen: es kommt zur Proliferation und Degeneration der Schwannschen Zellen sowie zu starken Veränderungen an Markscheiden und Axonen. Vermehrte Schwannsche Zellen und Makrophagen bewirken die Beseitigung und Verdauung degenerierter Markscheiden und Axone. Die Veränderungen an markhaltigen Nervenfasern beginnen hauptsächlich am Ranvierschen Schnürring. Organisches Quecksilber schädigt in einer bestimmten Dosierung ausschließlich die peripheren Nerven. Diese Befunde lassen vermuten, daß bei Patienten mit organischen Quecksilbervergiftungen mitunter nur Symptome von Schäden an sensiblen Nerven auftreten können.

Electron microscopic study on schizophrenia

SummaryBiopsies of a frontal gyrus from both schizophrenic and non-schizophrenic brains were examined by electron microscopy. The results in the schizophrenic brains are as follows:1.Within the cytoplasm of the nerve cell, the Golgi apparatus was remarkably prominent.2.Membranous structures, consisting of numerous interconnected tubules were observed in the nerve fibres. Abnormal structures appeared in the synapses and in many synapses vesicles were not observed.3.Granular and vesicular material accumulated in large amount in the axon-oligodendroglial interface of myelinated nerve fibres: the material was gradually transferred from the axon-oligodendroglial interface to the inner mesoaxon and the outer layers of the myelin sheaths destroying some of the myelin sheaths. Mainly myelinated nerve fibres of medium size were involved.4.A large amount of lipofuscin-like material was observed in the cytoplasm and the processes of the oligodendroglia.5.Only the neuron and the oligodendroglia showed specific changes. Among the findings mentioned above, (3) was thought to be specific and originated from the disturbance of the metabolism of the neuron, due probably to some enzyme disturbance in the neuron.

Ultrastructure of capillary plaque-like degeneration in senile dementia

SummaryBy electron microscopy cerebral cortex taken post portem from a case of senile dementia was examined especially with regard to “Drüsige Entartung der Hirnarterien” (Scholz, 1938).The basement mebrane of capillaries was irregularly enlarged, and had produced numerous amyloid fibrils and collagen. In the cytoplasm of the endothelial cells amyloid fibrils were also observed. Amyloid fibrils of the core of senile plaques would seem to be produced by the basement membrane of the blood vessels.

Experimental organic mercury poisoning—Regeneration of peripheral nerves

SummaryRats were given 1 mg of organic mercury compound per rat daily by mouth for 20 days. Peripheral nerves were examined on the 7th day and 250 th day after withdrawal of administration. On the 7th day, mitosis of Schwann cells was observed and on the 250 th day, myelinated fibres were noticeably decreased in numbers, with regeneration of nerve fibres and an increase of collagen in the intercellular spaces. Posterior nerve root ganglion cells were however intact. From this it is speculated that regeneration of injured peripheral nerve fibres, experimentally poisoned with organic mercury, is the result of regeneration of axons growing out to the periphery, and by regeneration of Schwann cells. Regeneration of the peripheral nerves was not however a very marked feature.ZusammenfassungRatten wurde oral durch 20 Tage täglich 1 mg organische Quecksilberverbindung verabreicht. Am 7. und 250. Tag nach Ende der Verabreichung wurden die peripheren Nerven untersucht. Am 7. Tag fanden sich Mitosen von Schwannschen Zellen und am 250. Tag deutliche Abnahme der myelinhaltigen Nervenfasern, begleitet von Regeneration der Nervenfasern und Zunahme von Kollagen im intercellulären Raum. Anderseits waren die Ganglienzellen der Hinterwurzeln intakt. Diese Befunde lassen vermuten, daß die Regeneration geschädigter peripherer Nerven nach experimentellen Vergiftung mit organischem Quecksilber durch bis in periphere Abschnitte wachsende Axonsprossen und neugebildete Schwann-Zellen vor sich geht. Die Regenerationstendenz der peripheren Nerven war jedoch im ganzen nicht sehr ausgeprägt.

Late changes in human sural nerves in Minamata disease and in nerves of rats with experimental organic mercury poisoning.

SummaryThe sural nerves of 2 human cases with Minamata disease and poisoned rats were examined histopathologically. Both showed similar findings: the myelinated nerve fibres were decreased in number, but small myelinated nerve fibres were increased: The latter were irregular in shape and their Schwann cells showed regressive changes, with high electron density of the cytoplasms and many glycogen granules. Onion, bulb formation was not found. According to fibre diameter histograms, the ratio of small myelinated nerve fibres of 2–5 μm showed a high percentage. A large number of the small myelinated nerve fibres were presumed to be regenerated nerve fibres. These findings are different from other peripheral neuropathies and may be characteristics of the late changes of the sural nerve induced by organic mercury compound.

Late changes in sciatic nerve of rats after a small dose of methyl methylmercury sulfide

SummaryWistar strain of male rats of 100–110 g were used, 5 for an experimental and 5 for control group. 1 mg of organic mercury (methyl methylmercuric sulfide: CH3HgSCH3) was given by mouth each day for 10 days (total dose 9–10 mg) to the experimental group. 600 days afterwards the experimental and control rats were killed.Only the peripheral nerves showed changes, small myelinated nerve fibres with thick myelin sheaths in groups. Around these fibres occurred extremely small myelinated nerve fibres and isolated large unmyelinated fibres, and appeared to be regenerated fibres. Destruction of myelin sheaths and cavity formation in the axons were observed in these fibres. The changes in the axons were remarkable at the nodes of Ranvier.

Electron microscopic studies concerning the structural mechanism of the development of mental disturbance in experimental chronic methamphetamine poisoning

SummaryIn 8 male albino strain guinea pigs, 1 mg/kg of methamphetamine HCl was injected daily for 7 months to 1 year to produce chronic methamphetamine intoxication and to study the fine structure of the brain electron microscopically. The following results were obtained:1.Coalescence of membranes, between axons at the nerve endings and between axons and dendrites, was found in the cortex of the cerebrum and limbic system, in the thalamus and hypothalamus. Membranous structures were found in all portions of the cytoplasm of the nerve cells.2.Within the cytoplasm of the nerve cell, coated vesicles were increased in number with hypertrophy and increase of endoplasmic reticulum within nerve fibres in the frontal, parietal, temporal and occipital regions, and in the limbic system. In view of these findings, as well as the clinical neurological symptoms in patients with methamphetamine poisoning, the coalescence of membranes between nerve processes and the appearance of membranous structures in all portions of nerve cell cytoplasm from body to nerve endings appear to represent the most important findings, they probably produce a profound disturbance in the system of nerve conduction and transmission.ZusammenfassungAmphetaminchlorid in Mengen von 1 mg pro kg pro Tag wurde 8 männlichen Meerschweinchen ungefähr 1 Jahr lang täglich injiziert, um eine chronische Amphetaminvergiftung zu erzeugen. Bei jedem vergifteten Tier wurde die Feinstruktur des Gehirns elektronenmikroskopisch untersucht. Die Befunde waren folgende:1.Verschmelzung der Membranen zwischen Axonen in den Nervenendigungen sowie zwischen Axonen und Dendriten wurden in der Großhirnrinde, im limbischen System, im Thalamus und Hypothalmus beobachtet; ferner wurde eine sich vom Cytoplasma bis zur Nervenendigung erstreckende Membranstruktur in diesen Hirnbereichen festgestellt.2.Im Frontal-, Parietal-, Temporal- und Occipitalhirn sowie im limbischen System fanden sich vermehrt membranbegrenzte Vesikel im Cytoplasma der Nervenzellen und verdicktes und vermehrtes ER in den Nervenfasern. In Anbetracht klinischer Symptome der Patienten mit Amphetaminvergiftung wurde angenommen, daß die Verschmelzung von Membranen zwischen Nervenfortsätzen und das Auftreten der Membranstrukturen in allen Teilen des Nervenzellcytoplasmas vom Perikaryon bis zur Nervenendigung die wichtigsten Befunde sind, die darauf hindeuten, daß die Vergiftungsvorgänge einen wesentlichen Einfluß auf das Leitungssystem der Nerven ausüben können.

A biopsy case of Landry-Guillain-Barré Syndrome

SummaryN. suralis taken from a patient showing the typical Landry-Guillain-Barré Syndrome was examined electron microscopically and showed degenerative changes of the myelin sheaths, Schwann cells, axons and unmyelinated nerve fibres. The changes in the unmyelinated nerve fibres might be concerned with disturbances of autonomic function.ZusammenfassungBiopsie-Material des N. suralis einer Patientin mit typischem Landry-Guillain-Barré-Syndrom wurde elektronenmikroskopisch untersucht. Es fanden sich degenerative Veränderungen, die sowohl die Myelinscheiden als auch Schwannsche Zellen und unmyelinisierten Nervenfasern betraffen. Vor allem die Veränderungen an unmyelinisierten Nervenfasern scheinen mit der Funktionsstörung autonomer Nerven in Beziehung zu stehen.

Characteristics of epilepsy in severely mentally retarded individuals

In order to clarify the characteristics of epilepsy in patients with severe mentally retarded (SMR) subjects, we analyzed 52 SMR subjects with epilepsy from the institute for SMR subjects at Kikuchi National Hospital, Kumamoto, Japan. A total of 61.5% patients had uncontrolled seizures which were resistant to treatment. The most common combinations of seizure types in those not responding to conventional anticonvulsants were generalized tonic–clonic seizures (GTCS) with tonic seizure and GTCS with atypical absence. Their clinical features were characterized by spastic paralysis associated with a slower background electroencephalogram and abnormal computed tomography scans of the head, suggesting the involvement of cortical damage. These findings suggest that a large proportion of epilepsy in SMR subjects does not respond to treatment and that the severity of organic brain damage may therefore affect the natural course of epilepsy in such patients.

Electron microscopic study on a case of idiocy: Astrocytes and mental deficiency

SummaryA biopsy of a frontal gyrus from a case of idiocy, without gross bodily symptoms or neurological signs, was examined by electron microscopy. The results of this examination were as follows: there was no destructive process in the cerebral tissue but inclusions were seen in the cytoplasm of the astrocytes and there was an abnormal increase in lipofuscin granules, in the cytoplasm of the nerve cells. The inclusions consisted of damaged endoplasmic reticulum and RNP granules. From these findings, it was considered that the physiological function of the astrocytes was disturbed, as the result of a disturbance in protein metabolism and that the function of the nerve cells was also disturbed, with an increase in lipofuscin granules. These changes seem to be intimately concerned with mental deficiency and part of intellectual function seems to depend on the functions of the glia cells.ZusammenfassungIn einem Fall von Schwachsinn ohne starke somatische und neurologische Symptome wurde eine Biopsie der Frontalwindung vorgenommen und das Material elektronenmikroskopisch untersucht: Bei Fehlen eines cerebralen Abbauprozesses fanden sich Einschlußkörperchen im Cytoplasma der Astrocyten und eine abnorme Zunahme der Lipofuscingranula im Cytoplasma der Nevenzellen. Diese Einschlußkörperchen erwiesen sich aus geschädigtem ergastoplasmischen Reticulum und RNP-Körperchen bestehend. Aus diesen Befunden wurde geschlossen, daß die physiologische Funktion der Astrocyten infolge einer Störung des Protein-Metabolismus in den Astrocyten beeinträchtigt war; außerdem war die Funktion der Nervenzellen durch die Zunhme der Lipofuscingranula sekundär gestört. Es scheint, daß die Veränderungen eng mit dem Schwachsinn zusammenhingen und daß die intellektuellen Funktionen teilweise von der Funktion der Gliazellen abhängen.