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Biomedical subjects

L Luo

Publications and source records attributed to L Luo.

At least 145 records · Page 8Linked to original sources
PubMed1998

The effect of intrathecal neuropeptide Y on the flexor reflex in rats after carrageenan-induced inflammation.

We examined the effects of intrathecal (i.t.) administration of neuropeptide Y (NPY) on the excitability of the flexor reflex in normal rats and 24 h after inflammation induced by subcutaneous carrageenan. In normal rats, i.t. NPY at low doses (10 and 100 ng) caused a brief facilitation of the flexor reflex with no subsequent depression. At higher doses (1 and 10 microg), the effect of NPY was mainly inhibitory, causing substantial and usually prolonged depression of the flexor reflex. At 24 h after the injection of carrageenan, when inflammation was at its peak, the magnitude of the reflex was increased and discharge duration became prolonged. I.t. NPY produced similar pattern of dose-dependent facilitatory and depressive effects on the flexor reflex. The facilitatory effect of i.t. NPY, particularly for the higher doses, was significantly enhanced in inflamed rats compared to normals. In contrast, the depressive effect of high doses of i.t. NPY was unchanged. These data suggest that the changes in levels of NPY and NPY receptors in the spinal cord known to occur after inflammation, are associated with an increased excitatory effect of this peptide.

Analysis of Variance↗
PubMed1998

Expression of mRNA encoding vasopressin V1a, vasopressin V2, and ANP-B receptors in the rat cochlea.

The expression of mRNAs encoding vasopressin V1a, V2, and ANP-B receptors in the rat cochlea was examined by PCR and in situ hybridization. After reverse-transcription of rat cochlear RNA, cDNA was amplified by PCR using pairs of primers specific to these receptors. After subcloning of the PCR products, clones with sequences identical to those cloned previously from the rat liver (V1a receptor), kidney (V2 receptor) and brain (ANP-B receptor) were obtained. The localization of expression of those receptors in the developing and adult rat cochlea was examined by in situ hybridization using 35S-labeled cRNA probes. The V1a and V2 receptors were expressed throughout the whole of the neonatal rat cochlea, while no expression was detected in the adult cochlea. The ANP-B receptor was expressed throughout the whole of the neonatal cochlea. In the adult cochlea, expression was observed in the spiral ganglion and the spiral ligament. These results suggest that vasopressin may play a role in the development of the cochlea, and that natriuretic peptide may play a role in the function of the spiral ganglion and the spiral ligament.

Aging↗
PubMed1998

Evidence for differential regulation of calcium by outer versus inner hair cells: plasma membrane Ca-ATPase gene expression.

The expression of mRNA encoding plasma membrane calcium ATPase (PMCA) subunit isoforms (1-4) and splice variants was examined in the adult and developing rat cochlea by PCR and in situ hybridization. High levels of PMCA mRNA expression were observed in the neurons of the spiral ganglion, and in hair cells. Spiral ganglion neurons expressed PMCA 1-3 beginning in embryonic development, reaching high levels shortly after birth, and continuing into adulthood. Inner hair cells expressed PMCA 1 at moderate levels from birth to the time of onset of cochlear function on postnatal day 12, and strongly from then until adulthood. Outer hair cells expressed PMCA 2 at high levels from shortly after birth through adulthood. The data suggest that the calcium clearance requirements of inner and outer hair cells are distinct. PMCA 2 is the isoform with the highest affinity for calmodulin, and has also been associated with high levels of inositol triphosphate. Its presence in outer hair cells suggests that regulation of the enzyme by calmodulin may be particularly important for this hair cell type. It further suggests that inositol phosphate may play a unique role in the outer hair cell.

Animals↗
PubMed1998

Expression of small-conductance calcium-activated potassium channels (SK) in outer hair cells of the rat cochlea.

Physiological evidence suggests that SK-type Ca2+-activated K+ channels participate in ACh-induced hyperpolarization of OHCs (outer hair cells). Based on the sequences published by Kohler et al. [(1996), Science, 273: 1709), we designed degenerated primers recognizing cDNA subunits of rSK1, rSK2 and rSK3. Using this consensus set of primers, we probed by PCR a rat organ of Corti cDNA library. Two PCR products of 707 base pairs with sequence identical to rSK3 and rSK2 were obtained and cloned to generate RNA probes for in situ hybridization in the rat cochlea. The subunit rSK2 showed hybridization in the organ of Corti, at the location of the OHCs. The expression of rSK2 by OHCs was confirmed by probing with PCR a poly(A) amplified OHC cDNA library. During development, rSK2 hybridization in the organ of Corti was negative at embryonic days E16, E18 and at P0, weak at P4 and stronger from P8 to adulthood. The subunit rSK2 could also be detected in the spiral ganglion from P4 to the adult stage. Contrary to rSK2, the subunit rSK3 did not show specific hybridization in the organ of Corti at the adult stage (P120) and only a weak expression was observed at P10 and P21. Our study demonstrates expression of rSK2 in OHCs. These potassium channels are good candidates to underlie the ACh-activated K+ currents recorded during patch-clamp recordings in isolated OHCs. The expression of rSK2 in the cochlear ganglion at the adult stage suggests that SK Ca2+-activated K+ channels may also participate in the repolarization of the auditory neurons after the action potential and may influence their firing patterns.

Animals↗
PubMed1998

Leydig cell protein synthesis and steroidogenesis in response to acute stimulation by luteinizing hormone in rats.

We examined the temporal relationship between protein synthesis and testosterone production by rat Leydig cells in primary culture. Leydig cells were isolated from adult control Sprague-Dawley rats and from rats that had received LH-suppressive testosterone and estradiol (TE) implants in vivo for 10 days. The cells were incubated for 1-4 h with [35S]methionine in the presence or absence of maximally stimulating ovine LH, and newly synthesized proteins were examined by two-dimensional PAGE autoradiography. Approximately 800-900 newly synthesized polypeptides were readily visible on all autoradiograms, most of which did not differ in the cells from intact control and TE-treated rats. Incubation of cells from the control and treated rats with maximally stimulating LH for 4 h in both cases resulted in significant increases in testosterone production and in three newly synthesized polypeptides. These polypeptides, along with two others that changed little in response to LH, were similar in apparent molecular mass, 30 kDa, but differed in isoelectric point. Time-course studies revealed a temporal relationship between stimulation of the three 30-kDa proteins and of testosterone production. Western blot analysis identified the 30-kDa proteins as steroidogenic acute regulatory protein (StAR). The results of these studies, for the first time utilizing primary cultures of highly purified, testosterone-producing Leydig cells, provide further correlative evidence of a role for StAR protein in the acute regulation of Leydig cell testosterone biosynthesis by LH.

Animals↗
PubMed1998

Three-dimensional optimization of treatment planning for gamma unit treatment system.

During a treatment using the Leksell gamma unit, the physician and physicist need to determine a treatment plan by changing the parameters such as collimator sizes, the position of isocenters and isocenters' weights. This is a complex problem because the set of parameters is large, especially when targets are geometrically close to a critical structure. For this reason, we present here an optimization algorithm, namely the multiplier penalty method, to mathematically determine those parameters. Two cases are presented in this article: the first one is really planned by a physicist in a clinical treatment, and is redone in our optimization algorithm to show the effectiveness of this method; the second one is theoretical where a critical structure is placed close to the target volume. The results show that this method achieves an excellent conformation to the specified isodose curve with the contour of the target volume, allowing minimal damage to surrounding healthy tissue.

Algorithms↗
PubMed1998

[Changes of plasma testosterone level in male patients with coronary heart disease].

The plasma testosterone (T), estrodiol (E), total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), HDL2-C, HDL3-C, apolipoprotein (apo) A1 and B100, and lipoprotein (a) [Lp(a)] were measured in 118 male patients with coronary heart disease (CHD) and 53 sex and age-matched healthy controls. The results showed that plasma T, HDL-C, HDL3-C levels and HDL-C/TC ratio were significantly lower and Lp(a) level was significantly higher in patients than in the controls. After adjusting body mass index, blood pressure and fasting blood glucose, the difference of plasma level between patients and controls persisted. Plasma T level correlated positively with the HDL-C, HDL3-C level and HDL-C/TC ratio and negatively with systolic blood pressure, apoB100 and Lp(a) level. Logistic regression was used to analyze the data, and this indicated that decreased T and HDL3-C levels, and increased Lp(a) level were the independent risk factors of CHD.

Aged↗
PubMed1998

[Experimental study on the role of insulin-like growth factor-I in ovulation induction].

OBJECTIVE: To investigate the possibility of insulin-like growth factor-I (IGF-I) as an adjunctive factor for ovulation induction. METHODS: The model of anovulatory mice was established by single injection of testosterone propionate. Thirty anovulatory mice were divided into 3 groups, each contained 10 mice. IGF-I 1 microgram + human menopausal gonadotropin (hMG) 5 IU, IGF-I 2 micrograms or hMG 10 IU alone was injected intraperitoneally to each group respectively. Cyclic changes of vaginal smear and numbers of oocytes in fallopian tubes were used to assess the effect. RESULTS: Vaginal smears of 8 mice in IGF-I + hMG group, 6 mice in hMG group and 2 mice in IGF-I group returned to normal cyclic pattern. The differences between IGF-I + hMG group and IGF-I or hMG groups were significant (P < 0.01 and P < 0.05), but the difference between IGF-I group and hMG group was not significant (P > 0.05). The average numbers of oocytes within fallopian tubes were 12.3 in IGF-I + hMG group and 9.2 in hMG group (P < 0.05). In IGF-I group there were no oocytes in the fallopian tubes of two mice whose vaginal smears returned to normal. CONCLUSION: IGF-I may be a potential agonist agent for ovulation induction.

Animals↗
PubMed1998

[The effect of insulin-like growth factor-I on steroidogenesis and ultrastructures of cultured human granulosa cells in vitro].

OBJECTIVE: To observe the effect of insulin-like growth factor-I (IGF-I) on steroidogenesis and ultrastructures of cultured human granulosa cells in vitro and the synergetic influence of follicle stimulating hormone (FSH) on this process. METHODS: Human granulosa cells were cultured in serum-free 1640 medium. After stimulated with various concentrations of IGF-I or IGF-I + FSH for 24 hours, estradiol (E2) and progesterone (P) levels in the media were measured by radioimmunoassay, and the ultrastructure changes of granulosa cells were observed under electronic microscope. RESULTS: When stimulated with different concentrations of IGF-I for 24 hours, E2 and P levels produced by granulosa cells were in a dose-dependent manner and significantly higher than those of controls (P < 0.01). The E2 and P levels in the media under the stimulation of IGF-I + FSH were 3.5 times and 14.5 times respectively higher than those of FSH alone. The main ultrastructureal appearances of granulosa cells stimulated with IGF-I were abundance of enlarged smooth enodplasmic reticulum, mitochondria and lipid droplets in cytoplasm. CONCLUSIONS: IGF-I possesses a positive effect on the steroidogenesis of cultured human granulosa cells in dose-dependent fashion which could be enhanced by combination of IGF-I and FSH. The ultrastructures of granulosa cells showed a tendency toward activation of steroidogenesis under the stimulation of IGF-I.

Cells, Cultured↗
PubMed1998

The influence of impaired microvasculature on regional blood flow of the spinal cord after microsurgery.

OBJECTIVE: To further investigate the impact of impaired microvasculature of spinal cord and its physiological compensation on postoperative morbidity after intramedullary microsurgery. METHODS: In 120 cats, the segmental anterior longitudinal spinal arteries (ALSA), the posterior longitudinal spinal arteries (PLSA), and the unilateral radiculomedullary arteries (RMA) were selectively coagulated in different patterns. Hydrogen electrode technique was used to detect the changes of regional blood flow of the spinal cord at different segments. Benzidine dihydrochloride (BDHC) staining was used to observe the microvascular pattern of the spinal cord, tetrazolium chloride (TTC) staining was applied to morphometric analysis of the ischemic area, and hematoxylin-eosin staining was applied to histologic examination. RESULTS: When the segmental ALSA was injured, the blood flow of the gray matter and white matter decreased greatly. Since the central arteries were the terminal blood supply arteries, no compensation occurred after the injury. The blood flow of the segment below the impaired segment hardly changed, indicating that the direction of the blood flow in ALSA altered to adapt the changes of the microvasculature. Injury to the unilateral PLSA and RMA at both cervical and lumbar area only caused a minor decrease in the regional blood flow, unless the perimedullary arterial system was considerably injured. In the thoracic medullary segment, the sparse microvasculature was the main cause for the segment vulnerable to ischemia and infarction. This was caused by not only the rarity of RMA as an anatomic factor, but also the small number and low activity of the neurons at this area. After microsurgery, the impairment and decompensation of the microvasculature were closely related to the ischemic volume of and pathological changes in the spinal cord. CONCLUSION: The impairment and decompensation of microvasculature after microsurgery are the rudimentary causes of spinal cord ischemia. During operation, one should protect the terminal arteries to decrease the severity of injury to the perimedullary system, and do the best to avoid disturbance of microvasculature to accelerate the recovery of postoperative ischemia and neurological dysfunction of the spinal cord.

Adaptation, Physiological↗
PubMed1998

[Regulation of ACTH4-9 analogue on the Ca2+ level of mouse hippocampal synaptosomes].

The effect of ACTH4-9 analogue Org2766 on the [Ca2+]i level of mouse hippocampal synaptosomes was studied. Synaptosomal free calcium concentration ([Ca2+]i) and 45Ca2+ uptake were measured respectively by spex cation measurement system and Beckman LS-9800 liquid scintillation spectrometer. Low dose of Org2766 did not change synaptosomal [Ca2+]i level, but decreased 45Ca2+ uptake. High dose of Org2766 increased [Ca2+]i without affecting 45Ca2+ uptake. Low dose of Org2766 inhibited the anisomysin-induced increase of synaptosomal [Ca2+]i while high dose had no effect. These results suggest that the regulation of Org2766 on hippocampal synaptosomal Ca2+ level may be achieved by inhibiting the Ca2+ influx and increasing the release of synaptosomal calcium pool.

Adrenocorticotropic Hormone↗
PubMed1998

[Study of protein separation by reversed-phase high performance liquid chromatography].

Reversed-phase high performance liquid chromatography (RP-HPLC) of protein on large pore silica (20-30 nm) n-alkyl-bonded(C4 and C5) phase columns was studied using a trifluoroacetic acid (TFA)/2-propanol mobile phase system. The influence of concentration of organic modifier (2-propanol) and ion-pairing acid (TFA) on the protein retention time was examined. The results showed that the plot of the retention time vs-2-propanol concentration in mobile phase was U-shaped. The mechanism of protein in reversed-phase high performance liquid chromatography is also discussed.

Alpha-Globulins↗
PubMed1998

[Clinical observation of yugengongyu decoction in treatment of coronary heart disease with angina pectoris].

OBJECTIVE: To observe the clinical effect of Yugengtongyu Decoction (YGTY) in treatment of coronary heart disease (CHD) with Qi deficiency, Blood stasis and phlegm stagnancy type and Qi deficiency and Blood stasis type. METHODS: Patients were divided into two groups, 45 cases in the YGTY group and 38 cases in the control group. In alleviating angina pectoris and improving symptom of CHD, the serum total cholesterol (TC), serum triglyceride (TG) were determined before and after treatment. RESULTS: The total effective rate of spontaneous angina pectoris were significantly better in the treated group than those in the control group (P < 0.005). In improving symptom of CHD were significantly better in the treated group than those in the control group (P < 0.005), and it was better the type of Qi deficiency, Blood stasis and phlegm stagnancy than type of Qi deficiency and Blood stasis in treated group (P < 0.05). TC of the treated group was lowered markedly after treatment, as compared with that before treatment, the difference was significant (P < 0.005). CONCLUSIONS: YGTY was effective for alleviating angina pectoris and improving symptom of CHD. It is best for the type of Qi deficiency, Blood stasis and phlegm stagnancy. It also has regulatory effect on the blood lipid.

Adult↗
PubMed1998

[Triterpenes and steroidal compounds from Momordica dioica].

Three triterpenes and two steroidal compounds were isolated from the dry root of Momordica dioica. Their structures were elucidated by spectral analyses (MS, IR, 1HNMR, 13CNMR and DEPT) and chemical methods. These compounds are alpha-spinasterol octadecanonate(I), alpha-spinasterol-3-O-beta-D-glucopyranoside(II), 3-O-beta-D-glucuronopyranosyl gypsogenin(III), 3-O-beta-D-glucopyranosyl gypsogenin(IV) and 3-O-beta-D-glucopyranosyl hederagenin(V). Constituent III is a new compound. The CHCl3 extract of Momordica dioica roots and five isolated constituents showed anticancer activity in pharmacologic testing on cancer cell(L1210). The growth inhibitory index(%) of compound II was shown to be 50%, at the dose of 4 micrograms.ml-1.

Animals↗
PubMed1998

[Histologic study for effects of ox collagen in forming of new bone with quantitative method in animal models].

In this study, collagen was implanted into mandibular defects of 10 dogs. After operations, the samples were examined with microscope and quantitative method at 10 periods. Results showed that collagen did not affect bone growth and new bone grew into collagen directly. There was no fibrous capsule between collagen and new bone. Eventually, majority of collagen was resorbed and replaced by bone tissue. It was concluded that collagen has a good histocompatibility.

Animals↗
PubMed1998

[Cellular compatibility study of ox collagen with fibroblast cells].

The cell culture method was used to evaluate the cytotoxicity of ox collagen for clinical use. Direct method was chosen to examine the shape and growth of cells. Results showed that the cell shape was normal and the growth was well. The cytotoxicity of ox collagen conformed to the standards made by International Organization for Standardization (ISO). This study demonstrated that ox collagen doesn't restrain the growth of cells and has good biocompatibility.

Biocompatible Materials↗
PubMed1998

[The study of multi-phrase multi-criterion steretactic radiotherapy treatment planning].

Steretactic radiotherapy treatment planning is an important part of X-knife radiosurgery. In this paper the theory of multi-phrase-multi-criterion steretactic radiotherapy treatment planning is proposed, which is composed of three phrases. In the first stage, linear programming is used to reduce the resolution space. A kind of quadriatic programming is used in the second phrase in order to get high and well-distributed dose distribution. In the third phrase, an improved method of constrained simulated annealing is used to get the effect of conforming with the clinical practice. In correspondence with three-phrases optimization, three criterions are used respectively. The experiment results show that the theory proposed is correct.

Humans↗