Biomedical subjects

L Xue

Publications and source records attributed to L Xue.

At least 91 records · Page 5Linked to original sources

PubMed1997

Low extracellular pH induces activation of ERK 2, JNK, and p38 in A431 and Swiss 3T3 cells.

The mechanism by which mammalian cells respond to low environmental pH is unclear. A wide range of environmental stresses are known to induce activation of MAP kinases ERK 2, JNK and p38 and recent work has shown that low pH can activate the p38 homologue in yeast HOG1. In this study we show that ERK2 MAP kinase is activated in human A431 cells exposed to low pH media. Activation is sustained throughout low pH treatment, is reversible, and occurs maximally at pH 4 or 5. Stimulation is not accompanied by tyrosine phosphorylation of the EGF receptor or Raf-1 activation, indicating that acid conditions act via pathways independendent of those required for EGF mediated MAPK stimulation. The MAP kinase homologue JNK and MAPKAP kinase-2 reactivating kinase (p38) were also activated in A431 cells by low pH and so low pH induces parallel activation of multiple MAP kinase pathways. Strong activation of p42, and p44 ERKs as well as p38 and JNK was also found in mouse Swiss 3T3 cells treated at pH 5. These results indicate that MAP kinases may be important markers of the acid induced cellular stress that occurs in human disease.

3T3 Cells↗

PubMed1997

Babesiasis in Nanjing area, China.

This article discusses the tick-borne babesiases which harm dairy cattle, buffaloes and dogs. In addition, the pathogen, vector, seasonal occurrence, hosts, symptoms, pathological changes and treatment are summarized and analysed. The pathogens in this area were identified as Babesia bigemina, B. bovis and B. gibsoni; the vectors as Boophilus microplus, Rhipicephalus haemaphysaloides, Haemaphysalis longicornis. Affected buffaloes were found from April to September, peak numbers occurred between May and July. Affected dairy cattle were most numerous in July and August. Hunting dogs were the most affected dogs. Infected dogs were found from February until the beginning of December; peak numbers occurred from September to November. Affected animals were acute cases. Symptoms and pathological changes were obvious, but jaundice was rare in dogs. Acaprin, acriflavine, imidocarb and berenil were used early and late. Their effect was ideal but resistance has developed to these drugs.

Acriflavine↗

PubMed1997

Novel benzamil-sensitive sodium-independent choline transport in the cestode Hymenolepis diminuta: evidence for sodium channels uptake at low pH.

The uptake of choline by the tegument of Hymenolepis diminuta was investigated. The Q10 at pH 7.0 was 1.7, with an Ea of 90 kJ.mol-1. Choline transport was pH sensitive: At pH 5.0, a Na(+)-independent mechanism predominated, which was inhibited by 100 nM benzamil, 130 mM Na+, and 300 microM verapamil. At pH 7.0, the Na(+)-independent mechanism was inhibited by 130 mM Na+, amiloride, and EIPA with IC50's of 130 microM and 30 microM, respectively, and by benzamil with IC50's of 100 pM (high-potency Benzamil Sensitive Component; HBSC) and 70 microM (low-potency Benzamil Sensitive Component; LBSC). Calcium-free saline enhanced choline uptake non-specifically. Lanthanum3+, Gd3+, gramicidin, nigericin, and high-K+ did not affect choline uptake at pH 5.0 or pH 7.0, and 10 microM verapamil was without effect at pH 5.0, suggesting no significant role for the electrical potential difference across the brush-border membrane, a Na+/H+ antiporter, a Na+/Ca2+ antiporter, or Ca2+ channels in choline uptake. Under physiological conditions, the HBSC accounts for approximately 25% of the total choline taken up at pH 5.0, while the LBSC accounts for approximately 55% of the choline taken up at pH 7.0. The data suggest novel choline transporting mechanisms; an HBSC which displays properties in common with apical Na+ channels, and a unique LBSC of choline transport.

Amiloride↗

PubMed1997

Induced hyperproliferation in epithelial cells of mouse prostate by a Western-style diet.

In this study the effects of a Western-style diet on epithelial cell proliferation in the prostate and bladder of C57BL/6J mice were investigated. The Western-style diet contained increased fat and low calcium and vitamin D, compared with AIN-76A control diet, at levels simulating human Western diets based on nutrient density. After feeding the Western-style and AIN-76A diets for 5 and 16 weeks, mice were infused with bromodeoxyuridine (BrdU) for 72 h using s.c. implanted osmotic pumps. Findings revealed that in bladder epithelium BrdU labeling indices were not significantly different (P > 0.05) between mice on the control and Western-style diets at both time periods. However, significant increases in BrdU labeling indices occurred in epithelial cells of the anterior (P = 0.024) and dorsal (P = 0.049) lobes, but not in the ventral lobe (P = 0.21), of the mouse prostate after feeding the Western-style diet for 16 weeks, compared with mice on the control diet. These findings demonstrate Western-style diet induction of epithelial cell hyperproliferation in anterior and dorsal lobes of the mouse prostate. The findings further suggest that these nutrients may have a role in human prostatic carcinogenesis, since the anterior and dorsal lobes of the mouse prostate are homologous with the human prostate in embryological origin and histological structure and carcinomas induced in rodent models have similar characteristics to those found in human prostatic cancer.

Animals↗

PubMed1997

Electrical responses of gastric smooth muscles in streptozotocin-induced diabetic rats.

Electrical responses of gastric smooth muscles produced by transmural nerve stimulation, acetylcholine, norepinephrine, or K-free solution were investigated in streptozotocin-induced diabetic rats, using intracellular microelectrode techniques. In muscles from diabetic rats, 1) the resting membrane potential remained unchanged, 2) slow waves disappeared or were markedly reduced in amplitude, 3) the excitatory junction potential was absent, and in most cases only an inhibitory junction potential of reduced amplitude was elicited, 4) the amplitude of the hyperpolarization generated after superfusion with K-free solution was reduced, 5) the sensitivity of the acetylcholine-induced membrane depolarization was increased, and 6) the norepinephrine-induced hyperpolarization was reduced because of functional loss of alpha- and beta-adrenoceptors. Thus diabetes mellitus caused functional impairment of neuromuscular transmission, reduced the maximum activity of the electrogenic pump, increased the sensitivity of muscarinic receptors, reduced the sensitivity of adrenoceptors, and reduced the myogenic activity in gastric smooth muscles. These alterations in the properties of smooth muscle may be involved in the diabetes-induced gastroparesis.

Acetylcholine↗

PubMed1997

Effects of DQ-2511, a novel prokinetic agent, on electrical activities of smooth muscle in the guinea pig stomach.

Electrophysiological experiments were carried out to investigate the prokinetic actions of DQ-2511 on isolated smooth muscle of the guinea pig stomach. DQ-2511 enhanced the myogenic gastric slow waves and cholinergic excitatory junction potential and reduced the frequency of slow waves and the nonadrenergic, noncholinergic, and nonnitrergic inhibitory junction potential, with no significant alteration of the resting membrane potential. The results suggest that the prokinetic actions of DQ-2511 involve excitatory actions directly on smooth muscle and indirectly on cholinergic transmission.

Animals↗

PubMed1997

Carbonic anhydrase isoenzymes I, II, III, and IV are present in human esophageal epithelium.

Carbonic anhydrase (CA) isoenzymes have been widely studied in the gastrointestinal tract, where they mediate membrane transport events and pH regulation. However, the esophagus has generally received scant attention. In an immunohistochemical study confirmed by Western blotting, we have detected for CA isoenzymes (CAI, II, III, and IV) in the epithelium of human esophagus. Isoenzymes I, III, and sometimes IV (< 10%) were present in the cytoplasm of basal cells and II and IV in the cytoplasm and cell surface membranes, respectively, of suprabasal cells (prickle cells). The localization of CAIV to the plasma membranes was confirmed by electron microscopic immunocytochemistry. CA was effectively divided at the basal-suprabasal interface between low-activity CAI and III (basal) and high-activity CAII and IV (suprabasal). Carbonic anhydrase in esophageal epithelial cells may have several functions: elimination of CO2 and metabolites, participation in membrane transport events during active cell growth, and pH regulation as a protective mechanism against acidic gastric reflux.

Blotting, Western↗

PubMed1997

[Effects of HE particles on medicinal plant Agastache rugosus (Fisch. et Mey.) O. Ktze].

The biological effect of HE particles on the seeds of Agastache rugosus was probed in experiments on board a retrievable satellite. The result shows that the germination rate of the seeds pierced by HE particles radiation appears rather low. The seeds hit by HE particles (piercing radiation or not) start to germinate two days earlier than those in the control group, and the first leaf emerges four to five days earlier than that in the control group. The resultant seedlings grow markedly faster. Variations take place in the nuclear types of chromosome. The yield of essential oils becomes slightly higher. No marked changes have been observed in the major chemical components of these oils.

Chromosomes↗

PubMed1997

[The effects of space condition on the germination of medicinal plant Carthamus tinctorius].

OBJECTIVE: To substantiate the effects of space condition on the growth and development of medicinal plants. METHODS: The seeds of Carthamus tinctorius L. were set up in retrievable satellites. After returning earth, the germination of these seeds were observed by electrophoresis. The isozymes of peroxidases, esterase and soluble proteins were also evaluated. RESULTS: The average seed germinative rate of the space flight group was higher than that of the earth controlled group, and the peroxidase activity of the space flight group was higher than that of the earth controlled group either. The electrophoresis patterns of isozymes and proteins between the space flight group and the earth controlled group showed only little difference in bud bursting stage. CONCLUSION: Weightlessness and radiation in space affect the germination of Carthamus tinctorius, and they show little effect on gene expression in the stage of germination. Weightlessness may be the important factor to improve the peroxidase activity.

Cosmic Radiation↗

PubMed1997

[Changes of cardiac function during +Gz exposure in rabbits].

Changes of cardiac function was studied during +Gz exposure in rabbits. Seven New Zealand rabbits were anesthetized and exposed to +2, +4, and +6 Gz (each for 30s, onset rate 1G/s, with 15 min interval in between). The left ventricular systolic pressure (LVSP), peak rate of left ventricular pressure rising (+dp/dtmax) and ECG were recorded. The results showed that during +2, +4 and +6 Gz exposures, LVSP decreased by 62.96% (P<0.01), 63.34% (P<0.01) and 82.01% (P<0.01) respectively, and +dp/dtmax decreased by 58.46% (P<0.01), 53.59% (P<0.01) and 63.06% (P<0.01) respectively, and the left ventricular end diastolic pressure decreased by 67.78 % (P>0.05), 332.74 % (P<0.01) and 500.54% (P<0.01) respectively, as compared with those of control. It is suggested that cardiac function is depressed with +Gz exposure.

Acceleration↗

PubMed1997

[Sequential changes in diamine oxidase activity after burn].

We invistigated the sequntial changes in plasma and intestinal diamine oxidase (DAO) levels in animals and patients after burn injury. The results were as follows: 1. The plasma DAO level in patients was increased significantly at 1, 3, 7, 14 d and returned to normal at 21 d postburn; 2. In pigs, the elevation of plasma DAO level was also found during the whole experiment, but only significantly so at 72 h postburn; 3. In scald rats, the DAO level was increased in plasma and decreased in intestine. The above results suggested that intestinal mucosa injury and DAO release into blood occurred after burn injury. The activity of DAO in plasma might be one of the marker to reflect injury of intestinal mucosa.

Adult↗

PubMed1997

[Prognostic factors of dermatomyositis: analysis of 119 cases].

In order to know the prognosis of dermatomyositis, 119 patients with dermatomyositis were investigated from June to September 1995 by Shanghai Medical Cooperation Center on Dermatomyositis. Ten prognostic factors were studied with Lifereg Procedure multiple factor analysis. The results showed that 2 and 5-year survival rates were 75.3% and 53.2% respectively. The most common cause of death was lung infection and then was malignant tumor. Unfavorable prognostic factors were old age, malignant tumor, interstitial lung disease, dysphagia, cardiac involvement, fever, failure of remission and steroid therapy alone. The survival curve showed that mortality rate was high in the first three years, less between three and seven years and none after seven years. The results showed that dermatomyositis is a disease with poor prognosis. Patients with dermatomyositis can be adversely affected by many factors and should be treated regularly with steroid and immunosuppresive drugs as early as possible.

Adolescent↗

PubMed1996

Epithelial cell hyperproliferation induced in the exocrine pancreas of mice by a western-style diet.

BACKGROUND: Pancreatic cancer is a common cause of mortality in the United States, with an estimated 27,800 people dying of the disease in this country in 1996. Epidemiologic studies have suggested that Western diets containing high fat, high protein, and low calcium contents are associated with increased incidence of pancreatic cancer. PURPOSE: We investigated whether a Western-style diet containing increased fat content and decreased calcium and vitamin D contents would induce epithelial cell hyperproliferation (excess cell duplication) or hyperplasia (excess cell accumulation) in the pancreas, as was previously demonstrated in the colon and mammary gland. METHODS: C57BL/6J mice at 4 weeks of age were randomly assigned to one of two groups of 14 mice each. One group received the control diet ad libitum, and the other group was given the Western-style diet ad libitum. After 6, 9, and 15 weeks on the diet, four or five mice per group were infused with 5-bromo-2'-deoxyuridine (BrdU) for 72 hours by use of subcutaneously implanted Alzet osmotic pumps. The mice were then killed, and the pancreas of each mouse was removed. In the exocrine pancreas with ductal secretion, the duct system (including interlobular and intralobular ducts and centroacinar [i.e., centroductular] cells) and acini were measured both histopathologically and immunohistochemically (BrdU) and were analyzed without knowledge of the source of the specimens. Two-way analysis of variance was carried out. All P values were generated from two-sided tests for statistical significance. RESULTS: The number of pancreatic ducts (interlobular, intralobular, and centro-acinar-cancer-prone regions in certain rodent models and in humans) and acini per mouse in the Western-style diet group was similar to that in the control diet group during the entire feeding period (P = .76, .32, .93, and .42, respectively). Statistically significant higher BrdU-labeling indices of the ductal interlobular and intralobular epithelial cells were seen in mice fed the Western-style diet than in mice fed the control diet during the entire observation period (P = .014 and .016, respectively). There was no statistically significant difference (P = .098) between both diet groups in the BrdU-labeling indices of the centroacinar epithelial cells. CONCLUSIONS: A Western-style diet induced pancreatic epithelial cell hyperproliferation in mice, further suggesting that increased fat content and decreased calcium and vitamin D contribute to the development of pancreatic neoplasms.

Animals↗

PubMed1996

Calcium influx in Trypanosoma brucei can be induced by amphiphilic peptides and amines.

The following study was undertaken to determine whether an inducible calcium influx pathway is present in intact bloodstream forms of Trypanosoma brucei. Fura-2 fluorescence was used to demonstrate that amphiphilic peptides and amines, including melittin, mastoparan and compound 48/80, each produced a dose dependent calcium influx across the plasma membrane. Calcium influx did not result from general disruption of membrane integrity, since a corresponding influx of ethidium bromide or other divalent cations was not observed. Instead, the calcium influx was selectively blocked by the calcium channel antagonists, La3+, Cd2+ or Ni2+, and was not affected by the Na+ channel antagonists, tetrodotoxin or amiloride. Activation of the trypanosome calcium influx pathway was dependent upon an intact membrane potential, and the rise in intracellular free calcium concentration ([Ca2+]i) was reversed upon membrane depolarization with gramicidin D. Changes in Ins(1,4,5)P3 did not accompany the calcium influx. Overall, these data provide the first evidence of an inducible calcium influx pathway in T. brucei, and describe methods to selectively manipulate this pathway.

Amines↗

PubMed1996

The functional conservation of proteins in evolutionary alleles and the dominant role of enhancers in evolution.

Drosophila paired- embryos can be rescued to viable adults by the evolutionary alleles prd-Gsb and prd-Pax3, which express the Drosophila Gooseberry and mouse Pax3 proteins under the control of the paired cis-regulatory region. As prd-Gsb uncovers a prd function involved in the proper abdominal segmentation of adults, evolutionary alleles, defined and constructed in this manner, may often be weak and thus serve to discover hitherto unknown functions of a gene. Our findings show that the Gooseberry and Pax3 proteins have conserved most or all functions of the related Drosophila Paired protein although their C-terminal halves appear unrelated in sequence but not in 3-D structure essential for function. It follows that the acquisition of new cis-regulatory regions rather than the divergence of the C-terminal coding regions has been the primary device for the functional diversification of the Drosophila genes paired and gooseberry and the mouse Pax3 gene. The operation of this mechanism in insects as well as vertebrates suggests a major role in evolution.

Alleles↗

PubMed1996

Model of mouse mammary gland hyperproliferation and hyperplasia induced by a western-style diet.

Mammary glands of female C57BL/6J mice were analyzed after they were fed a Western-style diet or control AIN-76A diet. The Western-style diet contained several risk factors found in human diets in geographic regions having increased risk for breast cancer: high fat and phosphate and low calcium and vitamin D. After they were fed these diets for 8, 14, and 20 weeks, mice were sacrificed, and mammary glands were removed for morphometric and radioautographic measurements. Although after the animals were fed the Western-style diet for 8 weeks the number of terminal ducts per mouse mammary gland (NTDMG) was similar in the Western-style and control diet groups, after they were fed the Western-style diet for 14 weeks (p < 0.05) and 20 weeks (p < 0.01) the NTDMG significantly increased compared with the control group. Moreover, there was a significant increase (p < 0.01) in the tritiated thymidine labeling index of mammary terminal ductal epithelial cells after 14 and 20 weeks of Western-style diet administration. Thus the Western-style diet induced increased epithelial cell proliferation and increased NTDMG in female mice when fed during young adult growth and development. The findings raise the possibility that the ingestion of a diet with Western-style fat and phosphate content and with low calcium and vitamin D may induce similar changes during the early development of the human mammary gland.

Animals↗

PubMed1996

Properties of the inhibitory junction potential in smooth muscle of the guinea-pig gastric fundus.

1. In circular smooth muscle of the guinea-pig gastric fundus, transmural nerve stimulation evoked a cholinergic excitatory junction potential (e.j.p.), and blockade of the e.j.p. by atropine revealed a non-adrenergic non-cholinergic (NANC) inhibitory junction potential (i.j.p.). 2. The amplitude of the e.j.p. was increased by apamin, suramin or NGnitro-L-arginine (L-NOARG), with no significant change in the membrane potential. 3. The i.j.p. consisted of two components (fast and slow); apamin inhibited the former, nitroarginine inhibited the latter, and suramin inhibited both components. 4. Apamin inhibited the hyperpolarization produced by adenosine 5'-triphosphate (ATP) but not by vasoactive intestinal polypeptide (VIP). Suramin inhibited the hyperpolarization produced by VIP but not by ATP. The sodium nitroprusside (SNP)-induced hyperpolarization was not blocked by apamin or suramin. L-NOARG or tetrodotoxin did not inhibit the hyperpolarization produced by ATP, VIP or SNP. 5. The data did not support the hypothesis that ATP, VIP or nitric oxide (NO) is the main transmitter responsible for generation of the NANC i.j.p. in the fundus. 6. Actions of L-NOARG suggest that endogenous NO may be involved in junctional transmission, mainly as an inhibitory modulator of cholinergic transmission.

Adenosine Triphosphate↗

PubMed1996

Properties of junction potentials in gastric smooth muscle of the rat.

In isolated smooth muscles of the rat stomach, the properties of electrical responses of the membrane elicited by transmural nerve stimulation were studied. The smooth muscle membranes were quiescent in the fundus and spontaneously active with slow waves and often action potentials superimposed on top of the slow wave in the antrum and pylorus. The maximum membrane potentials were larger in the antrum (-50 to -55 mV) than in the fundus (-40 to -45 mV). Transmural nerve stimulation elicited an excitatory junction potential (e.j.p.) which was followed by an inhibitory junction potential (i.j.p.) in the fundus, and an i.j.p. alone in the antrum. The e.j.p. was inhibited by atropine, indicating that this potential was cholinergic in nature. The amplitude of the e.j.p. was increased by apamin or nitroarginine, and the latter was more potent than the former. The i.j.p. was inhibited by apamin or nitroarginine, and was resistant to adrenergic and cholinergic blocking agents, and therefore this potential was non-adrenergic non-cholinergic (NANC) in nature. The inhibitory actions of nitroarginine on the i.j.p. were antagonized by L-arginine, suggesting the involvement of nitric oxide (NO) in this junctional transmission. The results indicate that smooth muscles of the rat stomach receive cholinergic excitatory and NANC inhibitory nerves, and that endogenous NO may either be partly responsible for the generation of the i.j.p. or may modulate the junctional transmissions.

Animals↗