In the visual pathway of frogs it is possible to apply low levels of NMDA chronically to the optic tectum and study the mechanisms underlying the stabilization of synapses developing within the CNS. ...Earlier studies (Cline and Constantine-Paton, 1990) found that chronic NMDA treatment of tecta innervated by two retinas results in a reduction of branching within the terminal arbors of retinal ganglion cells (RGCs). We now report that this same chronic NMDA treatment produces fine-structural changes in synaptic morphology as well as local synaptic rearrangements within the retinotectal neuropil. Chronic NMDA treatment of doubly innervated tecta was associated with a thickening or darkening of both pre- and postsynaptic densities. These changes in synapse morphology were restricted to the superficial neuropil of tecta in regions where reductions in branches of RGC axonal arbors were observed at the light microscopic level. The fine-structural effects were absent from similarly treated tecta innervated by only one eye, where RGC axonal arbor pruning was not observed. Stereological analyses indicated that the incidence of two or more presynaptic profiles converging on the same postsynaptic process was significantly increased in the NMDA-treated, doubly innervated tecta. This observed increase in synaptic clustering was not associated with a larger synaptic active zone, or with an increase in the number of synapses per unit volume. These data are discussed in the context of the hypothesis that chronic NMDA treatment raises the threshold for synapse stabilization in tectal neurons, causing the selective loss of poorly correlated synapses of both retinal and non-retinal origin from tectal neuropil that is innervated by two retinas: increased pre- and postsynaptic thickening could reflect greater efficiency in the remaining synaptic contacts and their closer spatial proximity on the same postsynaptic process is consistent with greater cooperativity and less competition.
Sf‐Caspase‐1 Spodoptera frugiperda (fall armyworm) caspase‐1 is the most studied effector caspase of Lepidoptera and its activation may lead cells to apoptosis (programmed cell death) when under UV ...irradiation or baculovirus infection. In the present study, we repressed the expression of Sf‐caspase‐1 in Sf9 (S. frugiperda 9) cells using constitutive RNA interference, and evaluated the effects of stress responses and the production of proteins in recombinant baculovirus‐infected cells. The Sf‐caspase‐1‐repressed stable cells, Sf9/pIBdsCasp‐1 and Sf9/pIBdsCasp‐2, showed a significant increase in resistance to UV‐ and baculovirus‐induced apoptosis. These cells produced higher levels of both intracellular (luciferase) and extracellular SEAP (secreted alkaline phosphatase) recombinant proteins than the parental cells when infected with recombinant baculovirus. Thus Sf‐caspase‐1‐repressed stable cells have a greater ability to adapt to various culture conditions, and also to provide the benefits of high‐level protein production.
The p53 tumor suppressor gene has been extensively studied in various human tumors including epithelial ovarian cancers. However, little is known about the expression of this gene in ovarian ...granulosa cell tumors, the most common histologic type of sex cord–stromal tumors. We investigated whether overexpression of the p53 gene product occurs in this specific ovarian tumor. Nineteen patients with ovarian granulosa cell tumors were recruited in this study. Immunohistochemical staining for the p53 protein with monoclonal antibody PAb 1801 was performed in the paraffin-embedded tissue of each case to screen for p53 overexpression. Among the 19 ovarian granulosa cell tumors, there was only one well-differentiated tumor found to have nuclear immunoreactivity in a small fraction of tumor cells. Polymerase chain reaction–single-stranded conformation polymorphism was used to study the tumor showing focal p53 positivity, but no mobility shift was noted from exon 4 through exon 9 of the p53 gene. On the basis of this observation, we propose that alteration of the p53 tumor suppressor gene is not a common finding in ovarian granulosa cell tumors.
A GaSb-based vertical external cavity laser at 2 Formula Omittedm was pumped by 100- to 160-ns pulses from a Nd : YAG laser at 1.064 Formula Omittedm operating at 1 kHz. It was shown that the output ...power scales with the pump spot diameter to the extent of our experiments. A peak output of over 340 W was obtained.
A GaSb-based vertical external cavity laser at 2 μm was pumped by 100- to 160-ns pulses from a Nd : YAG laser at 1.064 μm operating at 1 kHz. It was shown that the output power scales with the pump ...spot diameter to the extent of our experiments. A peak output of over 340 W was obtained.
The relative contribution and interrelated compensation of sympathetic signals among sympathetic components in pelvic plexus remain undefined. This study was designed to investigate the genitourinary ...function in response to autonomic nerve preservation and severance using a canine model.
Eighteen mongrel dogs were randomly divided into 3 groups which received severance of the hypogastric nerves on either the right side, left side, or on both sides. The hypogastric nerves and sacral sympathetic trunks were electrically stimulated and the contraction pressure of the internal urethral orifice was measured immediately, at 1- and 3-month intervals. The ejaculation function and the length of time required to reach sexual orgasm were evaluated by manual penis-stimulation.
The difference between the left and right sides of the normal hypogastric nerve in contribution to sympathetic signals was insignificant. Compared with the hypogastric nerve, the bilateral sacral sympathetic trunks were functionally trivial in controlling the closure of the internal urethral orifice. The preserved side of the hypogastric nerve compensated for the loss of sympathetic signals of the severed side within 1 month and, thereafter, remained stationary. In contrast, the functional compensation of bilateral sacral sympathetic trunks for the severed bilateral hypogastric nerves was insignificant. When the hypogastric nerve was preserved in one or both sides, all dogs maintained normal antegrade ejaculation. If bilateral hypogastric nerves were severed, 50.0% (3/6) of the dogs lost both emission and ejaculation function; 33.3% (2/6) presented with retrograde ejaculation; and, 16.7% (1/6) presented with combined retrograde ejaculation and reduced antegrade ejaculation. The time required to reach sexual orgasm was not affected by the severance of the hypogastric nerve.
The normal genitourinary function could be maintained only when at least one side of the hypogastric nerve was preserved.
A series of polyimide–mica hybrid films that consist of PMDA-ODA and mica were prepared by the solution ultrasonic dispersion technique, and characterized by XRD, UV–Vis transmission, cryogenic ...mechanical testing, dynamic mechanical analysis (DMA) and SEM. The effects of mica content and temperature on the cryogenic mechanical properties, dynamic mechanical properties, glass transition temperatures (
T
g) and morphologies of fracture surface were discussed. It was observed that the strength and stiffness of the hybrid films could be simultaneously increased when the mica content was lower than 10
wt%, and the tensile strength and modulus of the hybrid films at cryogenic temperature (77
K) were obviously higher than those at room temperature. Compared with pristine PI film, the hybrid films with 1–5
wt% mica contents would be more possibly used as advanced cryogenic materials in superconductive cable and magnet systems.
Peripheral T-cell lymphomas (PTCLs) are a heterogeneous group of non-Hodgkin lymphomas with a wide spectrum of clinicopathologic features, and apoptosis mechanisms may have a role in lymphomagenesis. ...We assessed apoptotic rate (AR) in 112 PTCLs using a tissue microarray developed in our laboratory and a modified terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay. The mean AR was 1.47% +/- 1.38% for the entire group of PTCLs (range, 0.06%-5.15%), and AR varied significantly among different tumor types. In mycosis fungoides, the mean AR was 0.74%; angioimmunoblastic T-cell lymphoma, 1.02%; PTCL, not otherwise specified, 1.38%; cutaneous anaplastic large cell lymphoma (ALCL), 1.41%; anaplastic lymphoma kinase protein (ALK)-negative ALCL, 1.43%; extranodal natural killer/T-cell lymphoma of nasal type, 2.04%; ALK-positive ALCL, 2.95%; and enteropathy-type T-cell lymphoma, 3.06%. Mean AR was higher in PTCL with large cell vs small/medium cell morphologic features (1.66% +/- 1.1% vs 0.99% +/- 1.0%). In a subset of 33 PTCLs, the tissue microarray results comparedfavorably with those obtained in full tissue sections. We conclude that the highest ARs in PTCLs are found in enteropathy-type T-cell lymphoma and ALK-positive ALCL, and that AR can be assessed reliably by using a tissue microarray.
PDF
