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Biomedical subjects

Q L Zhang

Publications and source records attributed to Q L Zhang.

34 records · Page 2Linked to original sources
PubMed1995

Neuronal sprouting in mouse sensory ganglia infected with herpes simplex virus type 2 (HSV-2): induction of growth-associated protein (GAP-43) and ultrastructural evidence.

Herpes simplex virus (HSV) is neurotropic and when inoculated on the mouse footpad is retrogradely transported to the associated dorsal root ganglia (DRG), where infection is established. Previous observations suggest that, after HSV infection, sensory ganglion neurons may mount a sprouting response. In our HSV-infected DRG model, we investigate this issue by (1) examining expression of growth-associated protein (GAP-43), a molecule known to be induced by growing axons, and (2) determining ultrastructurally whether HSV-infected dorsal roots contain neurites. In a time course study, we show that GAP-43 is induced both in HSV-infected DRG and their central processes. The increase in GAP-43 is first seen 2 weeks following unilateral footpad inoculation in both cell bodies and dorsal roots, and is sustained at 1 month post inoculation in roots but not in perikarya. Large bundles of unmyelinated small caliber axons, lacking Schwann cell ensheathment, are observed by electron microscopy in dorsal roots 2 weeks and 1 month following inoculation. These profiles resemble developing or regenerating neurites and are rarely seen in roots of mock-infected or uninfected controls. The increased GAP-43 immunoreactivity and ultrastructural changes shown here, in conjunction with previously documented selective neuropeptide and enzyme alterations, confirm that a sprouting response is mounted in sensory ganglia following acute HSV infection.

Animals↗
PubMed1994

Effects of nerve segment supernatants on cultured Schwann cell proliferation and laminin production.

Mouse sciatic nerves were transected and 3 hr to 16 days later proximal segments were removed and homogenized. Supernatants of these segments or of normal sciatic nerves were added to Schwann cells maintained in Dulbecco's modified Eagle's medium (DMEM) + 15% fetal calf serum (FCS). After 6 days, Schwann cells were solubilized and the protein content was measured using a Bio-Rad (Melville, NY) protein assay. Samples containing the same amounts of protein were then applied to microtiter plates and the laminin content was determined by enzyme-linked immunosorbent assay (ELISA). Lysates of cultures treated with 24 hr proximal segment supernatants contained significantly higher levels of laminin than those prepared from other intervals, from distal segments, or from control nerves. Increased surface and cytoplasmic anti-laminin immunoreactivity also was found in Schwann cells treated with 24 hr supernatants. To identify the source(s) of this effect, proximal segments removed 24 hr after transection were bisected; supernatants were prepared from each half and tested. Significant increases in laminin production were produced by supernatants from both halves. When supernatants from proximal and distal halves were compared, the latter produced significantly higher laminin levels. Electron microscopic examination of both halves showed that distal halves contained sprouting neurites and growth cones ensheathed by Schwann cells which had a basal lamina and resembled those seen during development and regeneration. Proximal halves appeared normal. Schwann cell proliferation also was compared in supernatant-treated cultures by using a bromodeoxy-uridine (BrdU) ELISA. The 24 hr and 2 day supernatants increased Schwann cell proliferation significantly; 12 hr, 4 day, and 8 day supernatants produced smaller increases. Our observations suggest that axons undergoing early regenerative changes are one of several possible sources of substance(s) in our proximal segment supernatants which increased Schwann cell proliferation and laminin production.

Animals↗
PubMed1994

[Self-made fibrin sealant administered in thoracic surgery].

From April 1990 to May 1993, 15 patients with thoracic complication or thoracic diseases have been treated with self-made fibrin sealant. All patients have been cured successfully in a short time without thoracotomy. The methods of its make-up, administer and assessment were discussed. It is economical and effective. The major advantage is simple method and easily administered. It could be used in other surgery.

Adult↗
PubMed1992

Myelinated fiber regeneration after sciatic nerve crush: morphometric observations in young adult and aging mice and the effects of macrophage suppression and conditioning lesions.

To study myelinated nerve fiber regeneration during aging, the right sciatic nerves of 6- and 24-month-old mice were crushed at the sciatic notch. Two, 4, and 8 weeks later, both groups of mice were perfused. The sciatic nerves were processed so that the transverse sections of each nerve subsequently studied by light and electron microscopy included the entire posterior tibial fascicle 5 mm distal to the crush site. Two weeks after axotomy, fascicles of aging mice contained significantly fewer regenerated myelinated fibers than those of young adults. After 4 weeks, the difference in the number of myelinated fibers was less. However, measurements of myelinated fibers in fascicles of aging mice showed that areas of Schwann cell cytoplasm and myelin were significantly reduced at all intervals. In contrast, although axon diameters in aging mice were somewhat less 2 weeks after crushing, the difference decreased with time, suggesting that in nerves of aging mice, regenerative responses of Schwann cells were more affected than those of axons. Other experiments in young mice showed that myelinated fiber regeneration could be retarded by suppressing macrophage responses and was not significantly changed by conditioning lesions before crush injury.

Adaptation, Physiological↗
PubMed1991

Fetal tissue grafts for cerebellar atrophy.

It has been shown in a rat model that surgical injury to the right cerebellum with resultant ataxia can be corrected by implantation of embryonic cerebellar tissue into the injured cerebellum. Histological examinations of the cerebellar tissue revealed that mitoses of Purkinje cells of the implanted group were increased substantially over the control group's. The surgically induced ataxia resolved more rapidly in the cerebellar implant group than the control group. Based on this experimental data, a similar technique was applied in 6 patients with severe hereditary cerebellar degenerative ataxia. The preliminary results in these 6 surgically implanted patients with heredity degenerative cerebellar disease show 2 with marked improvement, 3 with moderate improvement and 1 with improvement for 2 months followed by mild deterioration but still better than presurgery. We also studied immunological markers in the blood and CSF in an attempt to determine whether rejection of implanted tissue occurs.

Adult↗
PubMedDate not supplied

Aluminum impairs rat neural cell mitochondria in vitro.

Exposure to aluminum has been reported to lead to neurotoxicity. Mitochondria are important organelles involved in maintaining cell function. This study investigates the effect of aluminum on mitochondria in rat neural cells. The ultrastructure of mitochondria was observed, and the cell death rate (CDR), reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and 3-[4,5demethyl-2-thiazalyl]-2,-5diphenyl-2H-tetrazolium bromide (MTT) were measured to investigate the effect of aluminum on the mitochondrial structure and its function in neural cells. Results observed from the mitochondrial ultrastructure show that aluminum may impair the mitochondrial membrane and cristae. Increased CDR, enhanced ROS, decreased MMP, and decreased enzyme activity in mitochondria were observed in the Al-exposed neurons (100 500 microM). The present study demonstrates that alteration in the mitochondrial structure and function plays an important role in neurotoxic mechanisms induced by aluminum.

Aluminum↗