Biomedical subjects

J Y Li

Publications and source records attributed to J Y Li.

At least 37 records · Page 2Linked to original sources

PubMed2001

Is the postganglionic sympathetic neuron zinc-enriched? A stop-flow nerve crush study on rat sciatic nerve.

Axonal transport of endogenous zinc ions in the rat sciatic nerve was studied by a stop-flow/nerve crush technique combined with zinc selenide autometallography (ZnSeAMG) at light and electron microscopic levels. Distinct accumulations of ZnSeAMG grains were detected, in particular proximal but also distal to the crushes, 1.5 h after the operation, and the amounts of zinc ions increased further in the following 3-8 h. Ultrastructurally, ZnSeAMG grains were located predominantly in unmyelinated axons. The data suggest that a subpopulation of sciatic nerve axons contains and transports zinc ions both antero- and retrogradely, indicating that the second neuron in the sympathetic nervous system is zinc enriched (ZEN).

Animals↗

PubMed2001

Presence of sst2(a) receptor immunoreactivity in rat ependyma and tanycytes.

Somatostatin sst2(a) receptor was observed, by immunofluorescence, in ependymal cells and in tanycytes of the wall of the ventricle and the hypothalamic recess of the male rat median eminence. Strong immunoreactivity for the receptor protein was observed in lateral tanycytes (alpha-type) while a moderate signal was seen in medial tanycytes (beta-type). In high magnification the immunoreactive material, of moderate intensity, had a coarse granular appearance. Only few of the alpha-tanycytes also displayed immunoreactive GFAP. The apical portion of the ependymal cells as well as of tanycytes contained immunoreactive S-100 (alphabeta). Since rather high levels of somatostatin are demonstrated to occur in the cerebrospinal fluid of the third ventricle, it is suggested that somatostatin via the sst2(a) receptor may regulate the physiology of tanycytes.

Animals↗

PubMed2001

Agouti-related protein is a mediator of diabetic hyperphagia.

To explore the role of agouti-related protein (AGRP) in diabetic hyperphagia changes in hypothalamic AGRP mRNA levels were examined in diabetic rats. Rats rendered diabetic by streptozotocin displayed marked hyperglycemia (blood glucose 456.0+/-8.4 mg/dl versus 71.8+/-1.9 mg/dl) and hyperphagia (36.9+/-1.0 g/day versus 22.0+/-0.4 g/day), that was associated with a 286.6+/-4.4% increase in hypothalamic AGRP mRNA and a 178.9+/-13.5% increase in hypothalamic NPY mRNA. Insulin treatment of diabetic rats partially corrected blood glucose (147.4+/-13.1 mg/dl) and ameliorated hyperphagia (26.6+/-2.0 g/day). Insulin replacement was also associated with a return of hypothalamic AGRP mRNA (111.7+/-8.3% of controls) and NPY mRNA (125.0+/-8.9% of controls) from the elevated levels that were observed in untreated diabetic rats. In contrast to insulin treated rats, sodium orthovanadate treated diabetic rats remained significantly hyperglycemic (361.5+/-12.5 mg/dl). However, despite their persistent hyperglycemia, orthovanadate treated diabetic rats were still observed to have a significant reduction of hypothalamic AGRP mRNA (138.7+/-11.4%) and NPY mRNA (129.9+/-9.8%). Simultaneous measurement of serum leptin revealed suppressed levels in both untreated diabetic (0.5+/-0.1 ng/ml) and sodium orthovanadate treated rats (0.5+/-0.1 ng/ml) compared to non-diabetic controls (2.1+/-0.1 ng/ml). These data indicate that AGRP is a mediator of diabetic hyperhpagia and suggest that insulin can directly influence hypothalamic AGRP and NPY mRNA expression.

Agouti-Related Protein↗

PubMed2001

Carbachol induces homologous steroidogenic refractoriness of bovine fasciculata-reticularis cells.

Recently it was shown that the cholinergic agonist carbachol stimulates cortisol production in bovine ZFR cells via muscarinic receptor M(3). In the present study, we investigated the effect of chronic cholinergic stimulation on steroidogenic response and muscarinic receptor regulation in ZFR cells. Cortisol secretion of ZFR cells treated with 10(-4) M of carbachol decreased in a dose- and time-dependent manner. The carbachol-elicited loss of response was associated with a decrease in M(3) receptor number, which was also time- and dose-dependent. The down-regulation of the receptors was not associated with the decrease of M(3) receptor mRNA level. The marked steroidogenic desensitization caused by pretreatment of carbachol did not alter ACTH or angiotensin II activated steroid response. Northern blot analysis showed that carbachol pretreatment did not change the gene expression of P450scc, P450cl7, 3betaHSD and StAR mRNAs. These results suggest that carbachol induces homologous steroidogenic refractoriness of ZFR cells.

Adrenocorticotropic Hormone↗

PubMed2001

Determination of traces of 237Np in environmental samples by ICP-MS after separation using TOA extraction chromatography.

A simple, rapid, cost-efficient, and robust method for separation of 237Np with an extraction chromatographic column (TOA: tri-n-octylamine on Teflon powder) is outlined in detail and further improved for direct ICP-MS analysis. The column efficiently retained 237Np in 2 mol L(-1) HNO3 medium and all of the 237Np was easily eluted with 0.02 mol L(-1) oxalic acid in 0.16 mol L(-1) HNO3 at 95 degrees C. The separated solutions were free from most matrix elements and were aspirated into the ICP-MS directly. The decontamination factor for 238U is more than 10(4). The instrumental detection limit for 237Np was 0.46 pg mL(-1), which corresponds to 1.2 x 10(-5) Bq mL(-1). The method is more rapid than traditional radiometric techniques. It is also considered to be more suitable for environmental monitoring than existing methods based on TOA.

Journal Article↗

PubMed2001

In vivo proton MR spectroscopy of chorea-ballismus in diabetes mellitus.

The most common cause of chorea-ballismus (CB) is a vascular lesion; it is also associated with nonketotic hyperglycaemia in diabetes mellitus (DM) and may be the first manifestation of this disorder. We describe the CT, MRI and proton MR spectroscopy (1H-MRS) of CB in eight patients. Six had hemichorea-hemiballismus (HC-HB) and two bilateral CB. Single-voxel (SV) 1H-MRS was performed using point-resolved spectroscopy (PRESS). Voxels were positioned in the basal ganglia of the patients and control subjects. PRESS was also used to obtain spectroscopic imaging (1H-MRSI) of the slice of interest in two patients. CT showed a slightly dense striatum in all the patients with CB, and T1-weighted images revealed high signal. The CB correlated well with the neuroimaging findings. SV 1H-MRS showed the mean (+/- SD) N-acetylaspartate (NAA)/ creatine (Cr) ratio to be 1.45 +/- 0.19 in HC-HB and 1.82 +/- 0.06 on the opposite normal side (P = 0.01). The choline (Cho)/ Cr ratio was 1.3 +/- 0.12 in HC-HB and 1.11 +/- 0.13 on the opposite normal side (P = 0.005). A lactate peak was seen in seven patients. The NAA/Cr ratio was 1.44 +/- 0.15 in bilateral CB and 1.74 +/- 0.16 in the controls (P = 0.017); the Cho/Cr ratios were 1.36 +/- 0.1 and 1.19 +/- 0.07 (P = 0.015). The low NAA/Cr suggests neuronal loss or damage and the high Cho/Cr probably indicates gliosis. The presence of lactate may suggest mild ischaemia due to acute vascular events during hyperglycaemia and underlying chronic focal cerebrovascular diseases in DM.

Aged↗

PubMed2001

Ambuic acid, a highly functionalized cyclohexenone with antifungal activity from Pestalotiopsis spp. and Monochaetia sp.

Ambuic acid, a highly functionalized cyclohexenone, was isolated and characterized from Pestalotiopsis spp. and Monochaetia sp. these being biologically related endophytic fungi associated with many tropical plant species. This compound was found in representative isolates of these fungal species obtained from rainforest plants located on several continents. The relevance of ambuic acid to the biology of the association of these fungi to their host plants is also discussed.

Antifungal Agents↗

PubMed2001

Jesterone and hydroxy-jesterone antioomycete cyclohexenone epoxides from the endophytic fungus Pestalotiopsis jesteri.

Jesterone and hydroxy-jesterone are novel highly functionalized cyclohexenone epoxides isolated from a newly described endophytic fungal species--Pestalotiopsis jesteri. They were purified from cultures of the fungus by bioassay guided fractionation using Pythium ultimum as the indicator organism. Jesterone, in particular, displays selective antimycotic activity against the oomycetous fungi which are some of the most plant pathogenic of all disease causing fungi. The possible importance of these cyclohexenones to the biology of the endophytic fungus-host plant relationship is also discussed.

Alkenes↗

PubMed2001

Nonaspiration puncture biopsy for suspected thoracic cavum tumor: experience of 2,010 clinical cases.

In our hospital from October 1980 to February 2000, 2,010 patients with suspected thoracic cavum cancer were diagnosed by nonaspiration puncture with multiple-hole type and surface trough-type biopsy needles. The positive rate of cytology or pathology examination for lesions in pleura, mediastinum, and lung tissue were 88.6% (148/167), 83% (297/358), and 80.2% (1,191/1,485), respectively. The mean positive rate in all cases was 81.4% (1,636/2,010). Complications rates for pneumothorax or hemoptysis were 1.3% and 0.8%, respectively, in this group. Such revised puncture needles have been used by us in various organs, such as brain tumors, metastatic lymph nodes of head and neck cancers, malignant disease of breast, liver, kidney, prostate, rectum and bone, etc. The use of such nonaspiration puncture needles is very simple, safe, and effective; even for beginners with this technique, the rate of successful diagnoses is fairly high.

Biopsy, Needle↗

PubMed2001

Modulations of spinal serotonin activity affect the development of morphine tolerance.

To test whether modulations of spinal serotonin (5-HT) levels would affect the development of morphine tolerance, we treated rats with either intrathecal 5-HT or 5,7-dihydroxytryptamine (5,7-DHT; a 5-HT neurotoxin) in addition to systemic infusion with morphine (2 mg x kg(-1) x h(-1)). Continuous infusion of 5-HT (10 microg x 6 microL(-1) x h(-1)) into the lumbar subarachnoid space of rats for 9 h accelerated the development of morphine tolerance. The area under the curve for the tail-flick latency test was 454.1 +/- 35.1 in the Sham Control group vs 327.6 +/- 41.0 in the 5-HT-Infused group. mu-opioid receptor binding in the lumbar spinal cord showed a decrease in the Bmax (maximal binding -46.5%), but not the binding affinity (Kd), in 5-HT-infused rats. However, intrathecal injection of 5,7-DHT (50 microg), which resulted in a 48% reduction in 5-HT and 51% reduction in 5-hydroxyindoleacetic acid concentrations, led to an attenuation of morphine tolerance (the area under the curve was 613.0 +/- 24.7 in the 5,7-DHT-Lesioned group). The binding study indicated that the affinity of lumbar micro-opioid receptors decreased 196% in 5-HT-depleted rats, whereas there was no effect on apparent binding. The infusion of 5-HT (10 microg x 6 microL(-1) x h(-1)) was not analgesic and the 5,7-DHT-induced lesion did not affect acute morphine-induced analgesia. We conclude that activity of spinal 5-HT-containing neurons plays a crucial role during the development of morphine tolerance.

5,7-Dihydroxytryptamine↗

PubMed2001

Blood-brain barrier genomics.

The blood-brain barrier (BBB) is formed by the brain microvascular endothelium, and the unique transport properties of the BBB are derived from tissue-specific gene expression within this cell. The current studies developed a gene microarray approach specific for the BBB by purifying the initial mRNA from isolated rat brain capillaries to generate tester cDNA. A polymerase chain reaction-based subtraction cloning method, suppression subtractive hybridization (SSH), was used, and the BBB cDNA was subtracted with driver cDNA produced from mRNA isolated from rat liver and kidney. Screening 5% of the subtracted tester cDNA resulted in identification of 50 gene products and more than 80% of those were selectively expressed at the BBB; these included novel gene sequences not found in existing databases, ESTs, and known genes that were not known to be selectively expressed at the BBB. Genes in the latter category include tissue plasminogen activator, insulin-like growth factor-2, PC-3 gene product, myelin basic protein, regulator of G protein signaling 5, utrophin, IkappaB, connexin-45, the class I major histocompatibility complex, the rat homologue of the transcription factors hbrm or EZH1, and organic anion transporting polypeptide type 2. Knowledge of tissue-specific gene expression at the BBB could lead to new targets for brain drug delivery and could elucidate mechanisms of brain pathology at the microvascular level.

Animals↗

PubMed2001

Cloned blood-brain barrier adenosine transporter is identical to the rat concentrative Na+ nucleoside cotransporter CNT2.

Adenosine transport into brain is regulated by the activity of the adenosine transporter located at the brain capillary endothelial wall, which forms the blood-brain barrier (BBB) in vivo. To facilitate cloning of BBB adenosine transporters, poly A+ RNA was purified from isolated rat brain capillaries for production of a rat BBB cDNA library in the pSPORT vector. The cloned RNA (cRNA) generated from in vitro transcription of this library was injected into frog oocytes followed by measurement of [3H]-adenosine uptake. After dilutional cloning, a full-length, 2905-nucleotide adenosine transporter cDNA, designated clone A-11, was isolated. The A-11 clone yielded [3H]-adenosine flux ratios of 400 to 500 after injection of cRNA in oocytes. The adenosine uptake was sodium-dependent and insensitive to inhibition by S-(4-nitrobenzyl)-6-thioinosine (NBTI). The Km and Vmax of adenosine transport in the cRNA-injected oocytes were 23.1 +/- 3.7 micromol/L and 10.8 +/- 0.9 pmol/oocyte. min. The K0.5 for sodium was 2.4 +/- 0.1 mmol/L, with a Hill coefficient (n) of 1.06 +/- 0.07. DNA sequence analysis indicated the rat BBB A-11 adenosine cDNA was identical to rat concentrative nucleoside transporter type 2 (CNT2). The adenosine transporter activity of the rat BBB A-11 CNT2 clone is 50-fold more active than previously reported rat CNT2 clones. In summary, these studies describe the expression cloning of CNT2 from a rat BBB library and show that the pattern of sodium dependency and NBTI insensitivity of the cloned CNT2 are identical to patterns of adenosine transport across the BBB in vivo. These results suggest that BBB adenosine transport in vivo is mediated by CNT2, which would make CNT2 one of the few known sodium-dependent cotransporters that mediate substrate transport across the BBB in the blood to brain direction.

Adenosine↗

PubMed2001

Functional properties of an agouti signaling protein variant and characteristics of its cognate radioligand.

Agouti signaling protein (ASIP), the human (h) homolog of agouti, is an endogenous melanocortin peptide antagonist. To date, characterization of this protein has been performed with recombinant protein only and without the availability of an ASIP/agouti radioligand. In this report we describe the functional characteristics of a chemically synthesized truncated ASIP variant, ASIP-[90-132 (L89Y)], and the binding characteristics of its cognate radioligand, (125)I-ASIP-[90-132 (L89Y)]. Similar to full-length recombinant ASIP/agouti, ASIP-[90-132 (L89Y)] was a potent inhibitor of alpha-melanocyte-stimulating hormone cAMP generation at the cloned human melanocortin receptor (hMCR) subtypes hMC1R and hMC4R. It also displayed a lesser degree of inhibition at the hMC3R and hMC5R. However, ASIP-[90-132 (L89Y)] was found to be less potent than full-length recombinant ASIP and, surprisingly, only exhibited weak inhibitory activity at the hMC2R. In competition binding assays with the radioligand (125)I-ASIP-[90-132 (L89Y)], ASIP-[90-132 (L89Y)] displayed a hierarchy of binding affinity that roughly paralleled its rank order of inhibitory potency at the various MCR subtypes, i.e., hMC1R approximately hMC4R > hMC3R approximately hMC5R > hMC2R. Structure-activity studies revealed that ASIP-[90-132 (L89Y)] possessed greater pharmacological potency than either the further truncated ASIP variants ASIP-(116-132) or cyclo(CRFFRSAC). Interestingly, the latter molecules were both weak agonists at the hMC1R. These studies further support the concept that ASIP/agouti inhibits melanocortin action by directly binding to target MCRs and provide additional insight into the structural requirements for maximal inhibitory potency.

Agouti Signaling Protein↗

PubMed2001

Otx2 and Gbx2 are required for refinement and not induction of mid-hindbrain gene expression.

Otx2 and Gbx2 are among the earliest genes expressed in the neuroectoderm, dividing it into anterior and posterior domains with a common border that marks the mid-hindbrain junction. Otx2 is required for development of the forebrain and midbrain, and Gbx2 for the anterior hindbrain. Furthermore, opposing interactions between Otx2 and Gbx2 play an important role in positioning the mid-hindbrain boundary, where an organizer forms that regulates midbrain and cerebellum development. We show that the expression domains of Otx2 and Gbx2 are initially established independently of each other at the early headfold stage, and then their expression rapidly becomes interdependent by the late headfold stage. As we demonstrate that the repression of Otx2 by retinoic acid is dependent on an induction of Gbx2 in the anterior brain, molecules other than retinoic acid must regulate the initial expression of Otx2 in vivo. In contrast to previous suggestions that an interaction between Otx2- and Gbx2-expressing cells may be essential for induction of mid-hindbrain organizer factors such as Fgf8, we find that Fgf8 and other essential mid-hindbrain genes are induced in a correct temporal manner in mouse embryos deficient for both Otx2 and Gbx2. However, expression of these genes is abnormally co-localized in a broad anterior region of the neuroectoderm. Finally, we find that by removing Otx2 function, development of rhombomere 3 is rescued in Gbx2(-/-) embryos, showing that Gbx2 plays a permissive, not instructive, role in rhombomere 3 development. Our results provide new insights into induction and maintenance of the mid-hindbrain genetic cascade by showing that a mid-hindbrain competence region is initially established independent of the division of the neuroectoderm into an anterior Otx2-positive domain and posterior Gbx2-positive domain. Furthermore, Otx2 and Gbx2 are required to suppress hindbrain and midbrain development, respectively, and thus allow establishment of the normal spatial domains of Fgf8 and other genes.

Animals↗

PubMed2001

Mycoplasma infections and different human carcinomas.

AIM: To explore relationships between human carcinomas and mycoplasma infection. METHODS: Monoclonal antibody PD4, which specifically recognizes a distinct protein from mycoplasma hyorhinis, was used to detect mycoplasma infection in different paraffin embedded carcinoma tissues with immunohistochemistry. PCR was applied to amplify the mycoplasma DNA from the positive samples for confirming immunohistochemistry. RESULTS: Fifty of 90 cases (56%) of gastric carcinoma were positive for mycoplasma hyorhinis. In other gastric diseases, the mycoplasma infection ratio was 28% (18/49) in chronic superficial gastritis, 30% (14/46) in gastric ulcer and 37% (18/49) in intestinal metaplasia. The difference is significant with gastric cancer (chi(2) = 12.06, P < 0.05). In colon carcinoma, the mycoplasma infection ratio was 55.1% (32/58),but it was 20.9% (10/49)in adenomarous polyp (chi(2)=13.46, P < 0.005). Gastric and colon cancers with high differentiation had a higher mycoplasma infection ratio than those with low differentiation (P < 0.05). Mycoplasma infection in esophageal cancer, lung cancer, breast cancer and glioma was 50.9% (27/53), 52.6% (31/59), 39.7% (25/63) and 41% (38/91), respectively. The mycoplasma DNA was successfully amplified with the DNA extracted from the cancer tissues that were positive for mycoplasma infection (detected with antibody PD4). CONCLUSION: There was high correlation between mycoplasma infection and different cancers, which suggests the possibility of an association between the two. The mechanism involved in oncogenesis by mycoplasma remains unknown.

Antibodies, Monoclonal↗

PubMed2001

[The distribution and homology of mitochondrial plasmid-like DNAs in different cucumber varieties].

Four kinds of mitochondrial plasmid-like DNA, designated pC1, pC2, pC3 and pC4, have been found in cucumber (Jinyan No. 4). Their distribution in 14 Cucumber varieties was analyzed. Plasmid-like DNAs were detected in Jinchun No. 2, Jinchun No. 5, Jinxinmici, Jinlu No. 4 and Jinyan No. 4, and the rest 9 varieties contained no plasmid-like DNAs, suggesting that their distribution is irregular. There was homology among the same plasmid-like DNA family in different varieties. pC4 showed homology to the nuclear DNA of Jinyan No. 4, in addition to the nuclear genomes of other 7 varieties either with plasmid-like DNAs or without. The homologous sequences of pC4 in the cucumber nuclear DNA were repetitive. Sequences homologous to pC4 were also found in the nuclear genomes of towel gourd and pumpkin (other cucurbitaceous plant). Therefore, we propose that mitochondrial plasmid-like DNA occurred before cucumber diverged from cucurbit and had integrated into the nuclear DNA. The varieties without plasmid-like DNAs might lost them during evolution.

Cucumis sativus↗

PubMed2001

Sensitivity of diffusion-weighted magnetic resonance imaging in the diagnosis of acute lacunar infarcts.

BACKGROUND AND PURPOSE: Heightened interest in the early diagnosis and treatment of acute stroke challenges neuroimaging specialists to optimize available modalities and to develop new techniques for the evaluation of cerebrovascular disease. The purpose of this study was to evaluate the sensitivity of diffusion-weighted (DW) magnetic resonance (MR) imaging in detecting early small infarcts and in differentiating acute from nonacute small infarcts when conventional MR imaging demonstrates multiple small infarcts. METHODS: Thirty-eight consecutive patients with a clinical diagnosis of lacunar infarcts (20 men and 18 women, aged 50-79 yr) who underwent DW MR imaging within 3 days of symptom onset were enrolled in this study. All patients underwent both conventional fast spin-echo (FSE) MR imaging and DW MR imaging. Apparent diffusion coefficient (ADC) maps were also acquired. All patients had at least one of the following classic lacunar syndromes: pure motor hemiparesis, ataxic hemiparesis, dysarthria-clumsy hand, pure sensory stroke, and sensorimotor stroke. RESULTS: Thirty-six patients (40 acute lesions) had focal areas of high intensity on DW MR imaging associated with their clinical symptoms. Acute lacunar infarcts were seen on DW MR imaging as bright areas of decreased ADC ratio (range 0.31-0.85, mean 0.64). Lesion conspicuity with DW MR imaging was superior to that with FSE in 33 acute lesions. In four patients with small hyperacute (within 6 hours) infarcts, DW MR imaging was particularly sensitive for infarcts that were not visible on FSE sequences. The sensitivity of DW MR imaging and ADC map for acute lacunar infarcts was 95%, specificity 94%, positive predictive value 97%, negative predictive value 90%, and accuracy 95%. In 15 patients with both acute and nonacute old small infarcts, DW MR imaging and ADC map could easily distinguish the new infarct from adjacent old ones, although this distinction was difficult to make with FSE. CONCLUSIONS: DW MR imaging accompanied by ADC map is a sensitive diagnostic modality for hyperacute and acute lacunar infarcts. It is also sensitive in distinguishing fresh small infarcts from adjacent multiple old infarcts.

Acute Disease↗

PubMed2001

Combined conventional and jet ventilation in airway management in tracheal tumor.

Tumors on the carina are uncommon, and their anesthetic management can present a considerable challenge. The principle anesthetic consideration is ventilation and oxygenation in the face of an open airway. A 60-year-old man patient suffered a carinal tumor, which occupied 70% of the both main bronchi and bled spontaneously while coughing. Surgical resection and reconstruction were done. The carinal surgical approach was a right posterolateral thoracotomy, and the patient was placed in the left decubitus position. Because we could not insert the jet catheter past the mass, high frequency jet ventilation to ventilate the dependent lung could not be applied. Our choice was differential lung ventilation with a combination of conventional and high frequency jet ventilation modes to preserve oxygenation during tumor excision and tracheal reconstruction. An episode of desaturation was successfully treated during removal of tumor. The postoperative course was uneventful. The patient was sent to the intensive care unit after surgery and discharged on the 11th day. He received further combined chemotherapy and radiotherapy during his next admission. Fiberoptic examination on the 5 months later no evidence of recurrence. In summary, we described our airway management on carinal tumor excision, especially the tumor was so large that dependent lung jet ventilation could not employ.

High-Frequency Jet Ventilation↗