Biomedical subjects

D J Chute

Publications and source records attributed to D J Chute.

5 recordsLinked to original sources

PubMed1998

Immunocytochemical localization of tyrosine hydroxylase in the human striatum: a postmortem ultrastructural study.

An electron microscopic evaluation of tyrosine hydroxylase (TH) immunocytochemistry was used to describe the synaptic organization of dopamine innervation of the striatum in postmortem human brain tissue. TH immunoreactivity was qualitatively and quantitatively similar in the caudate and putamen. TH immunoreactivity was present mainly in unmyelinated axons and occasionally in myelinated axons. Both TH-immunoreactive (TH-i) varicosities (0.75-1.5 microm) and intervaricose segments (0.2-0.3 microm) formed synapses with spines and dendrites. Most synapses formed by TH-i profiles were symmetric axospinous (57-62%) or symmetric axodendritic (33-35%). An occasional asymmetric axodendritic or asymmetric axospinous synapse was observed. Approximately 35-50% of all symmetric axospinous and axodendritic synapses were formed by TH-i boutons. Synapses formed by TH-i profiles were short in length (0.226 microm) and had nonperforated postsynaptic densities. TH-i profiles formed synapses with both the head (40%) and the neck (60%) of spines. Typically, the TH-i bouton was apposed to both a spine and a nonlabeled terminal which formed an asymmetric synapse with that spine. Direct, nonsynaptic appositions were often seen between TH-labeled and nonlabeled boutons forming asymmetric synapses. The general pattern ofTH immunoreactivity was similar to that of other species except for the presence of TH-i myelinated axons and the observation that the majority of TH-i synapses were formed with spines rather than with dendritic shafts.

Adult↗

PubMed1998

Synaptic changes in the striatum of schizophrenic cases: a controlled postmortem ultrastructural study.

Although studies indicate abnormalities in the striatum of schizophrenic people, little information exists on the synaptic changes that may be present at the ultrastructural level. Autopsy specimens of striatal tissue from people with schizophrenia, normal controls, and psychiatric controls were obtained from the Maryland Brain Collection. Several abnormalities were noted in the schizophrenic group that were not present in the normal or psychiatric controls. In schizophrenic tissue, the density and/or proportion of symmetric synaptic profiles, particularly those ending on spines, were lower in the caudate vs. the putamen, implying an imbalance in inhibitory synaptic transmission between these two structures. The density of perforated synaptic profiles, cortical afferents thought to be involved in synaptic turnover and cognition, was lower in the striatum of the schizophrenic group compared to the control groups. The density of axodendritic synaptic profiles, particularly of the asymmetric type, was decreased in the caudate, but not the putamen, of a subset of schizophrenic cases that were nondyskinetic and off drugs (NDODS). The proportion of asymmetric axospinous synaptic profiles was elevated in the caudate of the NDODS cases in comparison to normal controls. The variety of synapses affected in the schizophrenic group implies the involvement of several neuronal circuits. The alterations observed in the schizophrenic striatum were usually due to changes in the caudate, but not the putamen, which argues against drug-related alterations. Since the striatum, particularly the caudate nucleus, is involved in cognition and emotion, these neuroanatomical changes could underlie, in part, aspects of schizophrenic psychopathology.

Adult↗

PubMed1998

Injury patterns in a plastic (AR-1) baton fatality.

Rubber and plastic bullets or batons have been used in countries outside the United States for several years. These devices were designed to inflict nonlethal force in riot control. The authors report a case of fatal injury sustained by an elderly woman struck in the chest by a plastic baton, including the circumstances surrounding this unusual incident, the autopsy findings and a review of the literature.

Fatal Outcome↗

PubMed1996

Synaptic organization of the human striatum: a postmortem ultrastructural study.

The goal of this study was to characterize the synaptic organization of the normal human adult striatum for comparison with other species and with the diseased human striatum. Samples of striatal tissue from the Maryland Brain Collection obtained at autopsy with postmortem intervals of less than 4 hours were prepared for electron microscopic analysis according to standard techniques. The caudate nucleus and the putamen were similar in terms of the proportions of synaptic subtypes, the lengths of synaptic subtypes, and the area of most types of axon terminals. The proportions of major striatal synaptic subdivisions, such as axospinous synapses (83.5%) and asymmetric synapses (77.5%), were similar to that of the monkey (82% and 77%, respectively) but slightly lower than found in the rat (90% and 89%, respectively). Interestingly, the proportion of synapses with perforated postsynaptic densities (23%), a type of synapse thought to represent synaptic plasticity, was much higher in humans than in rats (5-8%). The lengths of asymmetric synapses (0.697 micron) were significantly longer than that of symmetric synapses (0.423 microns), a relationship found in other mammals. Also, the areas of terminals forming asymmetric synapses (0.707 micron2) were larger than those forming symmetric synapses (0.401 micron2), also consistent with data from other species. The length of axospinous synapses (0.656 micron) and the area of the terminals forming them (0.611 micron2) were not significantly different from the length of axodendritic synapses (0.523 micron) or the area of terminals forming them (0.602 micron2). This study is the first quantitative study on synaptic organization in human postmortem striatum. The results indicate that the synaptic organization of the human striatum is similar, but not identical, to that of other mammalian species.

Adult↗

PubMed1996

Reduced striatal spine size in schizophrenia: a postmortem ultrastructural study.

Numerous studies using in vivo imaging or light microscopic analysis of autopsy specimens have found abnormalities in the striatum of schizophrenics. Striatal tissue from the Maryland Brain Collection with short postmortem intervals was used in the present study. Electron micrographs of striatal neuropil were digitized to determine the area of dendritic spines. Spines were similar in size in both the caudate and the putamen in normal individuals. The spines in tissue from schizophrenics were also similar in size between these two regions. However, striatal spines in schizophrenics were approximately 30% smaller than in controls (p < 0.05). Since the majority of synapses in the striatum are formed with spines, this change in the schizophrenic brain may represent aberrant synaptic conductance and/or efficacy.

Autopsy↗