表皮生长因子影响肿瘤患者舌苔变化的分子机制研究

目的 研究表皮生长因子（EGF）对食管癌细胞Eca-109细胞周期及表皮生长因子受体（EGF－R）表达的影响，探讨EGF促进肿瘤患者舌苔增厚的分子机制。方法 应用流式细胞术，检测EGF－R的表达和细胞周期。结果 EGF能明显促进Eca-109细胞膜上EGF－R的表达，使细胞增殖活性大大增强。结论EGF有是通过促进EGF－R的表达影响舌苔形成。     

人参单体皂甙Rh2对前列腺癌细胞株PC-3M细胞移行周期的影响

目的:探讨Rh₂对体外培养的PC-3M细胞移行周期的影响。方法:应用[³H]-TdR掺入法和流式细胞仪测定DNA含量及进行细胞周期的分析。结果:PC-3M细胞的[³H]-TdR掺入量明显少于对照组(P＜0.01);流式细胞仪测定G₁期细胞数百分比明显高于对照组。结论:Rh₂可使PC-3M细胞增殖周期阻滞在G₁期,肿瘤细胞增殖减慢。     

Maximal dynamic expiratory pressures with fast and slow inspirations

Maximal dynamic expiratory pressures are higher when forced expiration is preceded by a fast inspiration to total lung capacity (TLC) than when preceded by a slow inspiration and a few seconds pause at TLC. We hypothesized that these pressure differences are due to the stretch-shorten cycle (SSC), which refers to enhancement of muscle force when a concentric muscle contraction is immediately preceded by an eccentric contraction. Seven volunteers [36 (2) years; mean (SEM)] performed maximal forced expirations against minimal resistance with fast (F) or slow (S) maneuvers. F maneuvers consisted of a fast inspiration to TLC followed immediately by a fast expiration, whereas S consisted of a slow inspiration to TLC and a 4- to 5-s pause at TLC prior to forced expiration. We measured esophageal pressure (P _es), peak expiratory flow rate (PEFR), and the EMG activity of the transversus abdominis (Tr) by means of intramuscular fine-wire electrodes. The subjects performed several runs of each maneuver in a random order, and runs with the greatest expiratory P _es were analyzed. In comparison with S, F yielded greater P _es [182 (15) versus 167 (15) cmH₂O; P=0.003)] but similar PEFR [9.8 (0.7) versus 9.6 (0.7) l/s, P>0.05] and EMG activity of the Tr during forced expiration [221 (31) versus 208 (34) a.u., P>0.05]. Further analysis revealed significant EMG activity of Tr during end-inspiration (eccentric contraction) with F maneuvers only [73 (22) versus 32 (17) a.u., P<0.05]. We conclude that the ability of expiratory muscles to generate greater P _es with F maneuvers is related to the sequence of an eccentric contraction, which is followed immediately by concentric contraction in a manner analogous to SSC described in skeletal muscles. Electronic Publication     

Beta-amyloid activated microglia induce cell cycling and cell death in cultured cortical neurons

Immunocytochemical studies of postmortem human tissue have shown that the neurons at risk for degeneration in Alzheimer’s are marked by the ectopic expression of several cell cycle components. The current work investigates the roles that β-amyloid activated microglia might play in leading neurons to re-express cell cycle components. Stable cultures of E16.5 mouse cortical neurons were exposed to β-amyloid alone, microglial cells alone, or microglial cells activated by β-amyloid. Increased cell death was found in response to each of these treatments, however, only the amyloid activated microglial treatment increased the number of neurons that were positive for cell cycle markers such as PCNA or cyclin D and incorporation of BrdU. Double labeling with BrdU and TUNEL techniques verified that the ‘dividing’ neurons were dying, most likely through an apoptotic mechanism. The identity of the soluble factor(s) elaborated by the microglia remains unknown, but FGF2, a suspected neuronal mitogen, was ruled out. These results further support a model in which microglial activation by β-amyloid is a key event in the progression in Alzheimer’s disease.     

Regulation of phosphatidylinositol kinases by arachidonic acid in rat submandibular gland cells

Phosphoinositide kinases were characterized in membrane extracts of rat submandibular gland cells. Both phosphatidylinositol (PI) 4-kinase and phosphatidylinositol-4-phosphate (PI(4)P) 5-kinase phosphorylated endogenous substrates in reactions that were linear for up to 5 min, were activated by Mg²⁺ and showed maximal activity around neutral pH. PI 4-kinase was stimulated by Triton X-100 at an optimal concentration of 0.22%, but the detergent had an inhibitory effect on PI(4)P 5-kinase. Arachidonic acid (AA), at concentrations greater than 100 M, inhibited the activity of both enzymes in a dose-dependent manner. The inhibitory effect was replicated by other unsaturated fatty acids, but not by a saturated fatty acid of the sn-20 series. The nature of AA inhibition of the kinases was examined in enzyme kinetic studies with exogenous phosphoinositide and adenosine 5-triphosphate (ATP) substrates. Lineweaver-Burk plots of PI 4-kinase activity showed that AA had no effect on the apparent K _m for either PI or ATP, but that the fatty acid significantly reduced V _max (PI) from 331 to 177 pmol.mg^–1.min^–1 and V _max (ATP) from 173 to 59 pmol.mg^–1.min^–1. This inhibitory action was consistent for PI(4)P 5-kinase kinetics, where again, AA did not alter apparent K _m values, but lowered V _max for both PI(4)P and ATP by around 50%. Since the combination of a reduced V _max and an unchanged K _m value indicates noncompetitive enzyme inhibition, it is proposed that AA regulates phosphoinositide cycle activity in submandibular gland cells by acting as a noncompetitive inhibitor of PI 4-kinase and PI(4)P 5-kinase.     

Neuromuscular function and mechanical efficiency of human leg extensor muscles during jumping exercises

The influence of prestretch amplitude on the mechanical efficiency was examined with 5 subjects, who performed 5 different series of vertical jumps, each of which differed with respect to the mechanics of the knee joint action during the prestretch (eccentric) phase of the contact on the floor. Electromyographic activity was recorded from the major extensor muscles during the entire work period of 1 min per series. In addition, expired air was collected during the test and recovery for determination of energy expenditure. Mechanical work was calculated from the vertical displacement of the body during the jumps. The results indicated that high net efficiency of 38.7% was observed in condition where amplitude of knee bending in eccentric phase was small. In large range motion the corresponding net efficiency was 30.1%. In jumps where no prestretching of extensor muscles ocurred the net efficiency was 19.7%. The high efficiency of small amplitude jumps was characterized by low myoelectrical activity of the leg extensor muscles during the positive (concentric) work phase. In addition, the small amplitude jumps had shorter transition time in the stretch-shortening cycle, high average eccentric force and high stretching speed. Therefore the results suggest that the restitution of elastic energy, which was also related to the length change and stiffness of the muscles during stretch, plays an important role in regulating the mechanical efficiency of work.     

Mitochondrial aspartate glutamate carrier (citrin) deficiency as the cause of adult-onset type II citrullinemia (CTLN2) and idiopathic neonatal hepatitis (NICCD)

 By using homozygosity mapping and positional cloning, we have shown that adult-onset type II citrullinemia (CTLN2) is caused by mutations of the SLC25A13 gene, which is localized on chromosome 7q21.3 and encodes a mitochondrial solute carrier protein named citrin. So far, we have reported nine mutations, most of which cause loss of citrin, and we have established several methods for DNA diagnosis. These methods have shown that more than 90% of the patients diagnosed as suffering from CTLN2 by enzymatic analysis carry SLC25A13 mutations in both alleles, indicating that CTLN2 is caused by citrin deficiency. Furthermore, by using the same DNA diagnosis methods, we discovered that 70 neonates or infants suffering from a particular type of neonatal hepatitis carry the same SLC25A13 mutations. Since the symptoms of the neonates are different from those of the more severe CTLN2 and usually ameliorate without special treatment, we designated the neonatal disease neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD). We conclude that citrin deficiency causes NICCD in neonates and CTLN2 in adults through the additional effects of genetic or environmental modifiers. Since the function of citrin, together with that of an isoform, aralar, was found to be as a mitochondrial aspartate glutamate carrier, the various symptoms of NICCD and CTLN2 may be understood as caused by defective aspartate export from the mitochondria to the cytosol and defects in the malate aspartate shuttle. It is, however, still difficult to understand the cause of the hepatic deficiency of argininosuccinate synthetase protein in CTLN2. Received: March 20, 2002 / Accepted: March 28, 2002     

MTS1／p16抑制基因的克隆及其对宫颈癌细胞系的影响

利用重组ＲＴ－ＰＣＲ方法从人胎盘中扩增多重肿瘤抑制基因（ＭＴＳ１）全长ｃＤＮＡ片断，克隆测序后，亚顾隆入哺乳动物高铲表达质粒ｐＣＥＰ中。将表达质业转染两种遗传背影不同的吕颈癌细胞系，发现外源基因ＭＴＳ１／ｐ１６基因的导入对ＨＰ〖Ｖ阳性的宫颈癌细胞系具有明显生长抑制作用，并出现细胞滞留Ｇ１期的特性。     

QUANTIFICATION OF THE REM SLEEP CYCLE AS A RHYTHM

The goal of this study was to develop an objective quantitative method for representing the temporal organization of sleep in terms of the period and rhythmicity of REM sleep occurrences. Data on normative human sleep, already scored for stage REM and not stage REM, were subjected to a “binary autocorrelation.” The mean period over 92 nights of sleep for 10 Ss was 101.5 min and quite stable. Data is also presented on variability of the rhythm in terms of an “index of rhythmicity.” Measures of temporal organization may prove to be as significant for sleep research as amount of the various sleep stages.     

Effects of aging on luteinizing hormone release in different physiological states of the female golden hamster

Effects of aging on estrous cycles and LH release in response to luteinizing hormone releasing hormone (LHRH), castration, and estradiol benzoate were studied in the female golden hamster (Mesocricetus auratus). About 80% to 90% of female golden hamsters still cycled regularly when reaching 19–22 months of age. However, some animals showed age-induced irregularity of the estrous cycle which included an interruption of complete absence of estrous vaginal discharge. Young female hamsters (3–5 months) had significantly (p<0.01) higher basal LH concentration than old animals (19–22 months) in the morning of each stage of estrous cycle. LHRH elicited about 20–30 fold increase in serum LH concentrations in both young and old hamsters. No significant difference in LH release was observed between young and old hamsters in response to LHRH. In acyclic hamsters, the peak of LH release in response to LHRH was delayed. LHRH-induced LH release was greater in the morning of proestrus than during diestrus in both young and old hamsters. LH increase was significantly greater in the young than in old hamsters on the 13th and 15th day after castration. However, positive feedback stimulation of LH release by estradiol benzoate was the same in both young and old hamsters. These results indicate that in the female hamster, LH response to acute stimuli such as LHRH and estrogens is the same in the young as in the old animal and that circulating basal LH concentration may decrease or its degradation or clearance may increase during the aging process in female golden hamsters. Irregularity of estrous cycles in aging hamsters may be related to delayed responsiveness of pituitary LH to LHRH stimulation.