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81.
This study reports the establishment of alpha-amylase-producing human parotid pleomorphic adenoma cell lines (2HP and 2HP1) which have been maintained in culture for over 1 yr. The procedures required preparation of cellular clumps from tumor tissue and plating them on plasma clot or precoated dishes. During the initial phase of growth they required modified MCDB-153 medium without serum. When cells showed signs of degeneration they were changed to MCDB-153 medium containing first 2% and then 10% heat inactivated fetal bovine serum. Although cells grew well in MCDB-153 containing 10% serum, the epithelial cell morphology was not distinct. Therefore, the growth and morphology of cells grown in MCDB-10% serum were compared with those in RPMI growth medium containing 10% fetal bovine serum and F12 containing 10% agammaglobulin newborn bovine serum. Although the growth of cells was a little slower in F12 medium than those in MCDB and RPMI, the epithelial cell morphology was maintained better than in other growth media. The cells of 2HP and 2HP1 produce low levels of alpha-amylase and relatively high levels of alpha-amylase mRNAs of 1176 and 702 bp and contain neurofilament-160, a neuronal-specific marker. The cells of 2HP1 are tumorigenic when tested in athymic mice, but the cells of 2HP are not. The establishment of amylase-producing human parotid adenoma cell lines of different characteristics in culture provides a new opportunity to study the mechanisms of differentiation and transformation, and regulation of alpha-amylase in these cells.  相似文献   
82.
Rac, a member of the rho family of GTPases, when activated transmits signals leading to actin-based membrane ruffling in fibroblasts. Compared with wild-type fibroblasts, gelsolin null (Gsn-) dermal fibroblasts have a markedly reduced ruffling response to serum or EGF stimulation, which signal through rac. Bradykinin-induced filopodial formation, attributable to activation of cdc42, is similar in both cell types. Wild-type fibroblasts exhibit typical lamellipodial extension during translational locomotion, whereas Gsn- cells move 50% slower using structures resembling filopodia. Multiple Gsn- tissues as well as Gsn- fibroblasts overexpress rac, but not cdc42 or rho, 5-fold. Re-expression of gelsolin in Gsn- fibroblasts by stable transfection or adenovirus reverts the ruffling response, translational motility and rac expression to normal. Rac migrates to the cell membrane following EGF stimulation in both cell types. Gelsolin is an essential effector of rac-mediated actin dynamics, acting downstream of rac recruitment to the membrane.  相似文献   
83.
We report a family in which three siblings developed dementia between the ages of 40 and 70 years. Two of the siblings developed symptoms of depression, abnormal behavior, and an inability to function, progressing to severe dementia. The third sibling had a severe dementia, the clinical details of which are not available. In the two deceased siblings neuropathologic examinations demonstrated severe demyelination, axon loss, and gliosis in cerebral white matter. Cerebellar and brainstem white matter were unaffected. Cerebral gray matter was negligibly affected. The disorder, histopathologically classified as a pigmented orthochromatic leukodystrophy, is extremely rare. Its etiology is unknown, but the pathology and familial occurrence imply that it represents a genetic defect in a function localized in the cerebral white matter.  相似文献   
84.
OBJECTIVE: To examine the utility of single breath CO2 analysis as a noninvasive measure of cardiac output. SETTING: An animal laboratory in a university-affiliated medical center. DESIGN: A prospective, animal cohort study comparing 21 parameters derived from single breath CO2 analysis with cardiac output determined by an ultrasonic flow probe. SUBJECTS: Six healthy adult sheep. METHODS: The single breath CO2 analysis station consists of a mainstream capnometer, a variable orifice pneumotachometer, a signal processor, and computer software with capability for both on- and off-line data analysis. Twenty-one derived components of the CO2 expirogram were evaluated as predictors of cardiac output. Cardiac output was manipulated by successive injections of a hydraulic constrictor placed around the inferior vena cava. MEASUREMENTS AND MAIN RESULTS: Thirty-four measurements of cardiac output were available for comparison with derived variables from the CO2 expirogram. Stepwise linear regression identified two variables that were most predictive of cardiac output: a) the angle between the slope lines for phase II and III of the CO2 expirogram divided by the volume of CO2 per breath (angle/mL CO2); and b) the slope of phase II. The multivariate equation was highly statistically significant and explained 94% of the variance (adjusted r2 = .94, p < .0001). The bias and precision of the calculated cardiac output were .00 and .23, respectively. The mean percent difference for the cardiac output estimate derived from the single breath CO2 analysis station was 0.36%. CONCLUSIONS: Our data indicate that analysis of the CO2 expirogram can yield accurate information about the cardiovascular system. Specifically, two variables derived from a plot of expired CO2 concentration vs. expired volume predict changes in cardiac output in healthy adult sheep with an adjusted coefficient of determination of .94. Prospective application of this technology in the setting of lung injury and rapidly changing physiology will be essential in determining the clinical usefulness of the technique.  相似文献   
85.
GZ Markarian  JH Lee  DJ Stein  SC Hong 《Canadian Metallurgical Quarterly》1996,38(3):542-50; discussion 551
The treatment of cerebral ischemia remains a formidable challenge in neuroscience today. Mild hypothermia has been shown to be an effective neuroprotective agent. Despite the great volume of published research, the therapeutic window of mild hypothermia has not been precisely elucidated. Using a model of reversible focal cerebral ischemia in the rat, this study was undertaken to define the optimal duration of hypothermic application and the maximal postischemic delay in hypothermic application before which optimal therapeutic effect is noted. Focal ischemia was induced by temporary occlusion of the middle cerebral artery and both carotid arteries in Sprague-Dawley rats for a period of 3 hours. In the first study, mild hypothermia (32-33 degrees C) was induced at the onset of ischemia in four groups of rats for varying lengths of time ranging from 1 to 4 hours. The animals were killed after 3 days, and their brains were sliced and stained. Infarcted volume was measured using a computerized image analyzer. The infarct volumes were 211 +/- 4.5, 214.2 +/- 8.0, 199.5 +/- 5.3, 171.3 +/- 9.1, and 169.8 +/- 6.5 mm3 (mean +/- standard error of the mean, n = 6 per group) for the control, 1-hour, 2-hour, 3-hour, and 4-hour groups, respectively. On the basis of the results from the above study, a 3-hour duration of hypothermia was then applied to animals at 0, 15, 30, or 45 minutes after the ischemic onset. The volumes of infarction for these four respective groups were: 171.3 +/- 9.1, 173 +/- 5.7, 179.3 +/- 5.2, and 206.2 +/- 8.4 mm3 (mean +/- standard error of the mean, n = 6 per group). These results demonstrated that optimal duration of mild hypothermia was at least 3 hours (P < 0.001) when applied within the first 30 minutes after the onset of ischemia (P < 0.001).  相似文献   
86.
Temperature-regulated expression of recombinant proteins in the tac promoter (Ptac) system was investigated. Expression levels of fungal xylanase and cellulase from N. patriciarum in E. coli strains containing the natural lacI gene under the control of the Ptac markedly increased with increasing cultivation temperature in the absence of a chemical inducer. The specific activities (units per milligram protein of crude enzyme) of the fungal xylanase and cellulase produced from recombinant E. coli strain pop2136 grown at 42 degrees C were about 4.5 times higher than those of the cells grown at 23 degrees C and were even slightly higher when compared with cells grown in the presence of the inducer isopropyl beta-D-thiogalactopyranoside. The xylanase expression level in the temperature-regulated Ptac system was about 35% of total cellular protein. However, this system can not be applied to E. coli strains containing lacIq, which confers over production of the lac repressor, for high-level expression of recombinant proteins. In comparison with the lambda PL system, the Ptac-based xylanase plasmid in E. coli pop2136 gave a considerably higher specific activity of the xylanase than did the best lambda PL-based construct using the same thermal induction procedure. The high-level expression of the xylanase using the temperature-regulated Ptac system was also obtained in 10-litre fermentation studies using a fed-batch process. These results unambiguously demonstrated that the temperature-modulated Ptac system can be used for overproduction of some non-toxic recombinant proteins.  相似文献   
87.
URF13 is the product of a mitochondrial-encoded gene (T-urf13) found only in maize plants containing the Texas male-sterile cytoplasm (cms-T), and it is thought to be responsible for both cytoplasmic male sterility and the susceptibility of cms-T maize to the fungal pathogens Bipolaris maydis race T and Phyllosticata maydis. Mitochondria isolated from cms-T maize are uniquely sensitive to pathotoxins (T-toxin) produced by these fungi and to methomyl (a commercial insecticide). URF13 acts as a receptor that specifically binds T-toxin to produce hydrophilic pores in the inner mitochondrial membrane. When expressed in Escherichia coli cells, URF13 also forms hydrophilic pores in the plasma membrane if exposed to T-toxin or methomyl. Topological studies established that URF13 contains three membrane-spanning alpha-helices, two of which are amphipathic and can contribute to pore formation. Chemical cross-linking of URF13 was used to demonstrate the existence of URF13 oligomers in cms-T mitochondria and E. coli cells. The ability of the carboxylate-specific reagent, N,N'-dicyclohexycarbodiimide, to cross-link URF13 was used in conjunction with site-directed mutagenesis to establish that the URF13 tetramer has a central core consisting of a four-alpha-helical bundle which undergoes a conformational change after interaction with T-toxin or methomyl. Overall, the experimental evidence indicates that URF13 functions as a ligand-gated, pore-forming T-toxin receptor in cms-T mitochondria.  相似文献   
88.
We have examined dynamic events that occur on a time scale of minutes in an epithelial monolayer of Madine-Darby Canine Kidney (MDCK) cells and in ras-transformed MDCK cells by atomic force microscopy (AFM). Cells were imaged under physiological conditions, and time-lapse movies representing approximately 60 s real time per frame were assembled. In normal MDCK cells, two types of protrusions in the apical plasma membrane exhibit dynamic behavior. First, smooth bulges formed transiently over the time scale of minutes to tens of minutes. Second, spike-like protrusions appear initially as bulges, extend well above the apical surface and, finally, seem to detach. R5, an oncogenic transformant derived from MDCK cells, grows very flat on glass. During AFM imaging, these cells sometimes round up and detach from the substrate. In light microscopic observations of parallel preparations, cells rarely detach, suggesting that this is an active response of these cells to irritation by the AFM tip. R5 cells often extend processes that are supported by actin stress fibers. During imaging with the AFM, these processes withdraw at a rate of 1-5 microns/min, similar to that observed by light microscopy. During the withdrawal, movement of the stress fibers can be clearly seen. In the flat periphery of these cells, the transport of intracellular particles along cytoskeletal elements was seen. In addition, we have observed two types of wave-like movements through the cell, which appear to be an organized rearrangement of cytoplasm. One type of wave moves radially out from center of the cell while the other moves circularly along the cell periphery.  相似文献   
89.
Rotavirus (RV) strains infecting newborns often have unique neutralization antigens (P serotypes) on their outer capsids that are distinct from those found on RV strains that cause diarrhea in older children. We examined the hypothesis that unusual RV strains preferentially infect newborns because the newborns lack maternal neutralizing antibodies to these strains. To test this hypothesis, sera and saliva samples collected from neonates infected with 116E-like (P[11]G9) strains in the maternity ward of the All India Institute of Medical Sciences (AIIMS) hospital in New Delhi were tested for neutralizing antibodies against common RV strains and those infecting newborns and these titers were compared with those of newborns who did not become infected (controls). The infected neonates had significantly lower levels of cord blood neutralizing antibodies to 116E than the controls, suggesting that immunity to neonatal RV infection is acquired transplacentally through maternal antibodies. Further, this study confirmed the immunogenicity of the AIIMS neonatal strain 116E, a vaccine candidate, in its ability to evoke a potent RV-specific immunoglobulin A and neutralizing antibody response in serum and saliva among the infected babies. Our findings have important implications for the development of an effective RV vaccine. In India, where G9 strains are common in the community, the use of 116E as a vaccine, together with the rhesus tetravalent vaccine, may provide a broader protection against all the circulating RV serotypes, including serotype G9, which is not represented in the current rhesus RV tetravalent vaccine (G1-G4).  相似文献   
90.
Verrucous carcinoma is a variant of squamous cell carcinoma and should be distinguished from benign papilloma and well-differentiated nonverrucous squamous cell carcinoma. It is rare tumor of the sinonasal tract. Occasionally, conventional squamous cell carcinomatous components may be seen in verrucous carcinoma. This entity is called a hybrid verrucous squamous cell carcinoma. We report a case of hybrid verrucous squamous cell carcinoma occurring in the nasal cavity and paranasal sinus of a 67-year-old male. The removed mass shows the typical feature of verrucous carcinoma, but focally conventional squamous cell carcinomatous area is also noted. The treatment of this case follows verrucous carcinoma, but close follow up is mandatory because it may potentially spread to regional lymph nodes in contrast to pure form of verrucous carcinoma.  相似文献   
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