Cu(II), Co(II), Ni(II), Mn(II), and Fe(II) metal complexes containing N,N'-(3,4-diaminobenzophenon)-3,5-Bu(t)(2)-salicylaldimine ligand: Synthesis, structural characterization, thermal properties, electrochemistry, and spectroelectrochemistry.

The synthesis, structure, spectroscopic and electro-spectrochemical properties of steric hindered Schiff-base ligand [N,N'-(3,4-benzophenon)-3,5-Bu(t)(2)-salicylaldimine (LH(2))] and its mononuclear Cu(II), Co(II), Ni(II), Mn(II) and Fe(II) complexes are described in this work. The new dissymmetric steric hindered Schiff-base ligand containing a donor set of NONO was prepared through reaction of 3,4-diaminobenzophenon with 3,5-Bu(t)(2)-salicylaldehyde. Certain metal complexes of this ligand were synthesized by treating an ethanolic solution of the ligand with an equimolar amount of metal salts. The ligand and its complexes were characterized by FT-IR, UV-vis, (1)H NMR, elemental analysis, molar conductivity and thermal analysis methods in addition to magnetic susceptibility, electrochemistry and spectroelectrochemistry techniques. The tetradentate and mononuclear metal complexes were obtained by reacting N,N'-(3,4-benzophenon)-3,5-Bu(t)(2)-salicylaldimine (LH(2)) with some metal acetate in a 1:1 mole ratio. The molar conductance data suggest metal complexes to be non-electrolytes.

Transplantation of sciatic nerve segments into normal and glia-depleted spinal cords.

Although peripheral nerves are used as guides in attempts to enhance regeneration in the central nervous system (CNS), surprisingly little is known about the interface that develops between the host tissue and the transplanted or implanted peripheral nerve. This study examines host-nerve interfaces following transplantation of segments of sciatic nerve into the spinal cord under two differing conditions, one in which the spinal cord contains normal numbers of glia and one in which the glial population is reduced. The depletion of the glial population is achieved by exposing the lumbosacral region of the spinal cord in 3-day-old rats to X-rays, a model developed in this laboratory. Twenty days later, segments of fresh or frozen sciatic nerves harvested from other 3-day-old rats were transplanted into the lumbar region of spinal cord in irradiated animals and in their non-irradiated littermate controls. Following a 20-day postoperative period, the interfaces between host spinal cord and sciatic nerves were examined ultrastructurally, and pronounced differences were noted. A distinct scar composed of multiple layers of astrocyte processes completely enveloped the transplant in non-irradiated host spinal cord and confined Schwann cells and fibroblasts to the area enclosed by the scar. Terminals from axons that appeared to have traversed the transplant during this 20-day period ended blindly in the astrocytic scar. In contrast, a complete astrocytic scar failed to form around the transplant in the irradiated, glia-depleted hosts, and Schwann cells intermingled with host tissue. Some Schwann cells migrated away from the transplant, which was placed in the dorsal funiculus, along a perivascular route and extended into the gray matter. In some instances Schwann cells were observed in the ventral gray surrounding blood vessels and motoneurons. From these observations, it is clear that the formation of a distinct astrocytic barrier at the host-graft interface is greatly reduced irradiated host. The effects of astrocyte reduction on enhanced regeneration within the spinal cord are discussed.

Schwann cell invasion of ventral spinal cord: the effect of irradiation on astrocyte barriers.

This study examines a radiation-induced invasion and spread of Schwann cells into ventral gray regions of the lumbar spinal cord. The prevalence of these cells within the gray matter and the time course of their appearance in the ventral spinal cord is quite different from the pattern of Schwann cell development in dorsal spinal cord reported previously. The focus is on 2 possible pathways, each involving astrocytic barriers, by which Schwann cells access the ventral gray matter. The first of these is the glia limitans covering the ventral surface of the spinal cord and the possibility that its integrity has been disrupted by the exposure to x-rays. Comparisons of the glia limitans, including its thickness, between irradiated and nonirradiated rats revealed that exposure to radiation did not result in any morphologically discernible alterations. The second barrier examined was the astrocytic covering of blood vessels. In irradiated animals the astrocyte processes that normally surround blood vessels were missing in some instances, and Schwann cells were observed at these sites. The difference between the dorsal and ventral occurrence of Schwann cells is that, whereas Schwann cells primarily follow axons, specifically dorsal root axons, to access the dorsal spinal cord, it appears that the presence of Schwann cells in the ventral portion of the spinal cord where their location is primarily in the gray matter is associated with the vasculature.

Microglial development is altered in immature spinal cord by exposure to radiation.

Previous studies in this laboratory have documented that the microglial environment of the immature spinal cord is altered by exposure to ionizing radiation. As a result, the lumbosacral spinal cord is markedly depleted of both oligodendrocytes and astrocytes, while leaving axons and the overall cytoarchitecture intact. The status of the microglia in the irradiated region is unknown and is of interest given the interactions between microglia and astrocytes recently elucidated by others. This study uses both in vivo and in vitro approaches to examine the microglial population in normal and irradiated immature spinal cord. The lectin, Griffonia (Bandeiraea) simplicifolia, was selected since it marks microglia both in paraffin embedded sections and in cell cultures. Light microscopic examinations of spinal cord sections revealed a reduced microglial population in the irradiated region when compared to littermate controls, and a change in morphology of the remaining microglia to that described by others as "activated". Cultures prepared from lumbosacral spinal cords harvested from 3-day-old rats within 2-4 hr following irradiation were compared with cultures derived from their non-irradiated littermates after 8 days in vitro. Cultures from the irradiated spinal cords revealed trends similar to those observed in vivo, i.e. a reduced microglial population and altered morphology. Although all glial cell types were reduced in cultures from irradiated spinal cords, the few microglia present were usually positioned atop astrocytes. The consistency of reduction in all glial populations in this model shows the microglia to be a novel microenvironment for further studies of roles of microglial within the spinal cord.

Schwann cell-neuron relationships in spinal cord gray matter.

Schwann cells develop within the ventral gray matter following exposure of lumbosacral spinal cords to x-rays in early postnatal rats. These ventral gray matter Schwann cell aggregates occurred in about 40% of the animals 8 or more weeks following irradiation. Light microscopically these cells appeared to be apposed to somata of large motor neurons, raising a question regarding the fate of axo-somatic synapses. This study focused on neuron-Schwann cell relationships and demonstrated ultrastructurally that the intraspinal Schwann cells established a variety of relationships with the neuronal somata and primary dendrites. These relationships ranged from direct contact without an intervening basal lamina to the presence of synaptic contacts intervening between neuron and Schwann cell basal lamina. Occasionally, the Schwann cells occupied an intermediate position between neurons and blood vessels, suggesting functions similar to those carried out by astrocytes. In these instances, as in all cases of Schwann cell-blood vessel contact, the vessels lacked their normal investiture by astrocytes. Light microscopic evaluation of synaptophysin-immunostained sections revealed decreased immunoreactivity in neuropil occupied by the Schwann cells but confirmed the presence of synapses on neuronal somata. Possible mechanisms underlying Schwann cell induction in the ventral gray matter are discussed. An understanding of the interactions between Schwann cells and the cellular constituents of the gray matter is important in light of attempts to enhance repair in the central nervous system by transplanting Schwann cells into that environment.

The perceptual representation of voice gender.

The perceptual representation of voice gender was examined with two experimental paradigms: identification/discrimination and selective adaptation. The results from the identification and discrimination of a synthetic male-female voice continuum indicated that voice gender perception was not categorical. In addition, results from selective adaptation experiments with natural and synthetic voice stimuli indicated that the perceptual representation of voice adapted is an auditory-based representation. Overall, these findings suggest that the perceptual representation of voice gender is auditory based and is qualitatively different from the representation of phonetic information.

Conservative management of advanced bladder cancer.

Between January 1991 and October 1993, 32 consecutive patients with documented primary bladder tumours invading muscle received 3 cycles of methotrexate, vinblastin, doxorubicin and cisplatin (MVAC). The disease was re-staged by bimanual examination with the patient under anaesthesia, CT scanning and transurethral biopsy or resection. Of the 32 patients 2 underwent total or partial cystectomy and 30 did not, because re-staging showed no residual tumour in 8 (25%), stage T1-2 in 12 (37.5%) and far-advanced tumour in 10 (31.2%). The median follow-up was 2.8 years. Twelve patients with stage T1-2 tumour have required TUR, and cystectomy has not been necessary. Two patients who underwent total/partial cystectomy were all downstaged pathologically. Of the 10 failures 5 patients died of disease and 5 are alive with metastatic disease. The overall survival rate was 84.3% (27 of 32) and was 96.8% for patients with a functioning bladder. The data suggested that this active regimen can clinically induce downstaging in a significant number of patients with primary muscle-infiltrating bladder tumours. Transurethral resection plus MVAC chemotherapy is important for increased curability in patients with advanced bladder cancer.