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Biomedical subjects

Y Hua

Publications and source records attributed to Y Hua.

At least 91 records · Page 5Linked to original sources
PubMed1998

Stability determinants are localized to the 3'-untranslated region and 3'-coding region of the neurofilament light subunit mRNA using a tetracycline-inducible promoter.

The tetracycline-responsive expression system of Bujard was used to compare rates of decay of wild-type and mutant neurofilament (NF) light subunit (NF-L) mRNAs. Optimal conditions for activation and inactivation of the target transgene were determined using a luciferase reporter gene. Analyses of mRNA stability were thereupon conducted on cells that were doubly transfected with transactivator and inducible target genes and derived from pooled clones of transfected cells. Rates of mRNA decay were compared upon inactivation of the transgenes after high levels of mRNA had been induced. Deletion of the 445-nucleotide (nt) 3'-untranslated region (3'-UTR) (L/++(+)-) or 527 nt of the 3'-coding region (3'-CR) (L/++-+) increased the stability of NF-L mRNA compared with the full-length (L/++(++)) transcript in neuronal (N2a and P19 cells) and non-neuronal (L cells) lines. Deletion of both the 3'-UTR and 3'-CR (L/++--) led to a further stabilization of the transcript. A major stability determinant was then localized to a 68-nt sequence that forms the junction between the 3'-CR and 3'-UTR of NF-L and is the binding site of a unique ribonucleoprotein complex (Cañete-Soler, R., Schwartz, M. L., Hua, Y., and Schlaepfer, W. W. (1998) J. Biol. Chem. 273, 12655-12661). The studies establish a novel system for mapping determinants of mRNA stability and have applied the system to localize determinants that regulate the stability of the NF-L mRNA.

Animals↗
PubMed1998

Characterization of ribonucleoprotein complexes and their binding sites on the neurofilament light subunit mRNA.

Levels of neurofilament (NF) gene expression are important determinants of basic neuronal properties, but overexpression can lead to motoneuron degeneration in transgenic mice. In a companion study (Cañete-Soler, R., Schwartz, M. L., Hua, Y., and Schlaepfer, W. W. (1998) J. Biol. Chem. 273, 12650-12654), we show that levels of NF expression are regulated by altering mRNA stability and that stability determinants are present in the 3'-coding region (3'-CR) and 3'-untranslated region (3'-UTR) of the NF light subunit (NF-L) transcript. This study characterizes the ribonucleoprotein complexes that bind to the NF-L mRNA when cytoplasmic brain extracts are incubated with radioactive probes. Gel retardation assays reveal ribonucleoprotein complexes that are selectively competed with poly(C) or poly(U))/poly(A) homoribopolymers and are referred to as C-binding and U/A-binding complexes, respectively. The C-binding complex forms on the proximal 45 nucleotides of 3'-UTR, but its assembly is markedly enhanced by 23 nucleotides of flanking 3'-CR sequence. U/A-binding complexes form at multiple binding sites in the 3'-CR and 3'-UTR. A pattern of reciprocal binding suggests that the C-binding and U/A-binding complexes interact and may compete for common components or binding sites. Cross-linking studies reveal unique polypeptides in the C-binding and U/A-binding complexes. The findings provide the basis for probing mechanisms regulating NF-L mRNA stability and the relationship between NF overexpression and motoneuron degeneration in transgenic mice.

Animals↗
PubMed1998

Role of blood clot formation on early edema development after experimental intracerebral hemorrhage.

BACKGROUND AND PURPOSE: Blood "toxicity" is hypothesized to induce edema and brain tissue injury following intracerebral hemorrhage (ICH). Lobar ICH in pigs produces rapidly developing, marked perihematomal edema (>10% increase in water content) associated with clot-derived plasma protein accumulation. Coagulation cascade activation and, specifically, thrombin itself contribute to edema development during the first 24 hours after gray matter ICH in rats. In the present study, we sought to determine whether blood clot formation is necessary for edema development by comparing intracerebral infusions of heparinized and unheparinized blood in pig (white matter) and in rat (gray matter). We also examined heparin's effect on thrombin-induced gray matter edema. METHODS: In pigs, we infused autologous blood (with or without heparin) into the cerebral white matter to produce lobar hematomas and froze the brains in situ at 1, 4, or 24 hours after ICH. We determined hematomal and perihematomal edema volumes on coronal sections by computer-assisted morphometry. In rats, we infused either blood or thrombin (with or without heparin) into the basal ganglia and measured water, sodium, and potassium contents at 24 hours after ICH. RESULTS: In pigs, unheparinized blood induced rapid (at 1 hour) and prolonged (24 hours) perihematomal edema (average volume, 1.29+/-0. 20 mL; n=6). No perihematomal edema was present following heparinized blood infusions (n=6). In rats, unheparinized blood produced significantly greater edema than heparinized blood infusions. As with whole blood, thrombin-induced gray matter edema at 24 hours was significantly reduced by coinjection of heparin. CONCLUSIONS: After ICH, blood clot formation is required for rapid and prolonged edema development in perihematomal white and gray matter. Thrombin also contributes to prolonged edema in gray matter.

Animals↗
PubMed1998

Early metabolic alterations in edematous perihematomal brain regions following experimental intracerebral hemorrhage.

OBJECT: The authors previously demonstrated, in a large-animal intracerebral hemorrhage (ICH) model, that markedly edematous ("translucent") white matter regions (> 10% increases in water contents) containing high levels of clot-derived plasma proteins rapidly develop adjacent to hematomas. The goal of the present study was to determine the concentrations of high-energy phosphate, carbohydrate substrate, and lactate in these and other perihematomal white and gray matter regions during the early hours following experimental ICH. METHODS: The authors infused autologous blood (1.7 ml) into frontal lobe white matter in a physiologically controlled model in pigs (weighing approximately 7 kg each) and froze their brains in situ at 1, 3, 5, or 8 hours postinfusion. Adenosine triphosphate (ATP), phosphocreatine (PCr), glycogen, glucose, lactate, and water contents were then measured in white and gray matter located ipsi- and contralateral to the hematomas, and metabolite concentrations in edematous brain regions were corrected for dilution. In markedly edematous white matter, glycogen and glucose concentrations increased two- to fivefold compared with control during 8 hours postinfusion. Similarly, PCr levels increased several-fold by 5 hours, whereas, except for a moderate decrease at 1 hour, ATP remained unchanged. Lactate was markedly increased (approximately 20 micromol/g) at all times. In gyral gray matter overlying the hematoma, water contents and glycogen levels were significantly increased at 5 and 8 hours, whereas lactate levels were increased two- to fourfold at all times. CONCLUSIONS: These results, which demonstrate normal to increased high-energy phosphate and carbohydrate substrate concentrations in edematous perihematomal regions during the early hours following ICH, are qualitatively similar to findings in other brain injury models in which a reduction in metabolic rate develops. Because an energy deficit is not present, lactate accumulation in edematous white matter is not caused by stimulated anaerobic glycolysis. Instead, because glutamate concentrations in the blood entering the brain's extracellular space during ICH are several-fold higher than normal levels, the authors speculate, on the basis of work reported by Pellerin and Magistretti, that glutamate uptake by astrocytes leads to enhanced aerobic glycolysis and lactate is generated at a rate that exceeds utilization.

Adenosine Triphosphate↗
PubMed1998

[Comparison of the effects of inhaled nitric oxide and intravasculare regitine on pulmonary gas exchange in young dogs with oleic-acid acute lung injury].

In order to find an agent which truly improves hypoxemia of some serious pediatric lung diseases, the authors examined the independent effects of nitric oxide inhalation and regitine infusion on blood gases, intrapulmonary shunt and hemodynamics in young dogs with oleic-acid acute lung injury. After nitric oxide inhalation, the results showed moderate increases in PaO2 and SaO2 (P > 0.05) and a significant decrease in Qs/Q tau ratio (P < 0.01). There was a significant decrease of PAP(P < 0.05), while SAP remained unchanged. After regitine infusion, however, there were marked decreases in PaO2 and SaO2 (P < 0.01); meanwhile, Qs/Q tau rose (P < 0.05). These suggest that with the presence of pulmonary pathology nitric oxide inhalation may alleviate the elevated pulmonary pressure without alteration in systemic artery pressure; so it can improve pulmonary ventilation-perfusion distribution and cause favorable changes in blood gases. On the other hand, regitine, as a non-selective vasodilator, reduces pulmonary artery pressure at the cost of significant worsening of blood oxygenation and systemic hypotension; so its routine use in childhood pulmonary diseases should be cautiously considered.

Animals↗
PubMed1998

[Grouping of thoracic lymph nodes on CT scan according to American Thoracic Society classification].

OBJECTIVE: To assess the usefulness of the classification developed by the American Thracic Society (ATS) in the grouping of thoracic lymph nodes on CT scan. METHODS: Ten patients suffered from lymphoma (5 cases), sarcoidosis (2 cases) and metastatic lymphadenopathy (3 cases) were examinated with CT. The intrathoracic lymph nodes were grouped according to the ATS nodal classification. RESULTS: Six areas were divided on the CT scans: (1) between the upper margin of the sixth cervical vertebra and the pulmonary apex, including nodes in group 1R/L; (2) between the pulmonary apex and the upper margin of the aortic arch, including nodes in group 2R/L and 6; (3) between the upper margin of aortic arch and the carina, including nodes in group 4R/L, 5, 6 and 10R; (4) within 3 cm below carina, including nodes in group 7 and 10R/L; (5) between 3 cm from subcarina and the top of diaphragm, including nodes in group 8R/L and 14R/L; (6) intrapulmonary area, distal to the upper lobe bronchi, including nodes in group 11R/L. CONCLUSION: The division of lymph nodes into six areas on CT scan makes the ATS lymph node classification more easily applicable.

Humans↗
PubMed1998

[Effect of +Gz-induced cerebral ischemia on the distribution of nitric oxide synthase in rabbit brain].

In order to study the effect of repeated short termed + Gz -induced cerebral ischemia on rabbit brain, rabbits were exposed to +4.0 Gz for 3 times (with 30 min interval in between) which caused the arterial pressure at eye level dropped to 0 kPa and lasted for 30 s. Changes of distribution of the nitric oxide synthase(NOS) positive neurons in rabbit brain were observed using the NADPH-diaphorase histochemical reaction. The results showed that NOS positive neurons in the parietal cortex, piriform cortex, hippocampus and dentate gyrus increased by 167%, 126%, 321%, 172% (P < 0.01) respectively, immediately after repeated + Gz exposures, as compared with those of controls. It still remained significantly more than that in controls (P < 0.01) 1 h and 6 h after exposure. It suggests that NO may have some effect on the neurons during cerebral ischemia.

Acceleration↗
PubMed1997

In vitro activation of the mouse mid-sized neurofilament gene by an NF-1-like transcription factor.

In vitro transcription using nuclear extracts from rat brain and liver were used to assess the tissue-specific and functional elements of the mouse neurofilament mid-sized gene promoter (pNF-M). Deletion from -2.7 to -103 (relative to the start site of transcription) resulted in a small increase (2-fold) in the activity of the NF-M promoter in both extracts. Promoter strength was slightly higher in brain vs. liver extracts. Deletion to -49 resulted in a 10-fold loss of promoter activity in brain extracts and 6-fold drop in liver. Transcription in both extracts was TATA box-dependent. The region between -65 and -40 was shown to contain sequences responsible for high-level NF-M promoter activity in brain and liver extracts. Within this region are Sp1 and NF-1-like binding sites. Mutation of the NF-1-like site (-53/-39) caused a large drop in the activity of the NF-M promoter while mutation of the Sp1 site (-64/-57) possibly slightly diminished promoter activity in brain and liver extracts. Both the Sp1 and NF-1-like sites were shown by gel shift competition and supershift assays to be able to bind their respective factors. We conclude that the basic mouse NF-M promoter is a promiscuous promoter whose activity is modulated by a NF-1-like transcription factor. The lack of tissue specificity in an in vitro system strongly suggests an important role for chromatin structure in the regulation of the mouse NF-M promoter.

Animals↗
PubMed1997

[Clinico-transcranial Doppler sonography monitoring on vasospasm and delayed cerebral ischemia after resection of intracranial tumors].

The occurrence of vasospasm and delayed cerebral ischemia after resection of intracranial tumor has not received extensive attention clinically, and is often misdiagnosed and improperly treated as surgical brain damage or brain swelling. Seventy-two patients with intracranial tumor were continuously monitored pre- and postoperatively by means of neurological assessment and transcranial Doppler sonography. Vasospasm was found in 35 (48.6%) patients (18 mild, 13 moderate and 4 severe vasospasm). No significant difference among age, sex, surgical approaches, pathological diagnosis, duration of surgery, amount of blood loss and transfusion during surgery were found, but significant difference was seen in cisternal hemorrhage on CT scan and the amount of blood in cerebrospinal fluid. The cause and features of postoperative vasospasm were discussed, transcranial Doppler sonography played an important role in the diagnosis of vasospasm. To decrease the amount of blood in basal cistern by microsurgery in preventing vasospasm and to differentiate vasospasm from brain swelling are helpful to confirm the coexistent or causal relation based on neurological assessment, CT imagine, transcranial Doppler sonography and ICP monitoring both in deciding therapeutic strategy and successfully controlling vasospasm. Nimotop played a key role in preventing brain damage from vasospasm and cerebral swelling.

Adenoma↗
PubMed1996

Injection of complementary DNA encoding interleukin-12 inhibits tumor establishment at a distant site in a murine renal carcinoma model.

Interleukin (IL-12) protein has been shown to elicit diverse immunological responses and potent antitumor activity. We demonstrate here that intradermal injection of IL-12 cDNA induces systemic biological effects characteristic of the cytokine in vivo. Intradermal injection of IL-12 cDNA resulted in local expression of IL-12 mRNA, which correlated with a 10-fold increase in natural killer activity and a 3-4-fold increase in anti-CD3-induced IFN-gamma production in cultured splenocytes. Furthermore, when challenged with Renca tumor cells at a distant site, the day of tumor emergence was significantly delayed, and tumor growth was reduced in mice that received IL-12 cDNA, compared to mice given injections of plasmid vector alone. A number of the mice receiving IL-12 cDNA injections remained tumor free months after tumor challenge. In contrast to mice receiving recombinant IL-12 protein, no splenomegaly was detected when natural killer activity was significantly induced in mice receiving injections of IL-12 cDNA. Because purified plasmid DNA is more economical to prepare and has a longer shelf-life than recombinant proteins, and intradermal administration of cDNA encoding IL-12 did not cause splenomegaly, our findings suggest that the in vivo injection of cDNA encoding IL-12 may be a less toxic and more cost-effective alternative to IL-12 protein therapy in some clinical or experimental therapeutic applications.

Animals↗
PubMed1996

Lobar intracerebral hemorrhage model in pigs: rapid edema development in perihematomal white matter.

BACKGROUND AND PURPOSE: The mechanisms underlying brain injury from intracerebral hemorrhage (ICH) are complex and poorly understood. To comprehensively examine pathophysiological and pathochemical alterations after ICH and to examine the effects of hematoma removal on these processes, we developed a physiologically controlled, reproducible, large-animal model of ICH in pigs (weight, 6 to 8 kg). METHODS: We produced lobar hematomas by pressure- controlled infusions of 1.7 mL of autologous blood into the right frontal hemispheric white matter over 15 minutes. We froze brains in situ at 1, 3, 5, and 8 hours after hematoma induction and cut coronal sections of hematoma assessment, morphological brain examination, and immunohistochemical and water content determinations. RESULTS: At 1 hour after blood infusion, "translucent" white matter areas were present directly adjacent to the hematoma. These markedly edematous regions had a greater than 10% increase in water content (>85%) compared with the contralateral white matter (73%), and this increased water content persisted through 8 hours. In addition, these areas were strongly immunoreactive for serum proteins. Intravascular Evans blue dye failed to penetrate into the brain tissue at all time points, demonstrating that this serum protein accumulation and edema development were not due to increased blood-brain barrier permeability. CONCLUSIONS: Experimental lobar ICH in pigs models a prominent pathological feature of human ICH, ie, early perihematomal edema. Our findings suggest that serum proteins, originating from the hematoma, accumulate in adjacent white matter and result in rapid and prolonged edema after ICH. This interstitial edema likely corresponds to the low densities on CT scans and the hyperintensities on T2-weighted MR images that surround intracerebral hematomas acutely after human ICH.

Animals↗
PubMed1996

Hepatic lipase mediates the uptake of chylomicrons and beta-VLDL into cells via the LDL receptor-related protein (LRP).

The uptake of triglyceride-rich lipoproteins has been described as being mediated by apolipoprotein E and lipoprotein lipase (LpL). Proteoglycans, the LDL-receptor, and the LDL receptor-related protein (LRP) are the cellular acceptors. In addition to LpL, hepatic lipase (HL) has been shown to bind to LRP. In this study, the role of HL in lipoprotein uptake was investigated. Human chylomicrons and rabbit beta-VLDL were used as ligands for human hepatoma cells, primary human hepalocytes, normal and proteoglycan-deficient Chinese hamster ovary (CHO) cells, and normal and LDL receptor-deficient human fibroblasts. We show that HL induces stimulation of the uptake of chylomicrons and beta-VLDL into the different cell lines. HL is known to bind to heparan sulfate, and experiments on normal and proteoglycan-deficient CHO cells showed that cell surface proteoglycans are essential for HL-mediated uptake of lipoproteins. To exclude LDL receptor-mediated uptake. we performed experiments on LDL receptor-deficient fibroblasts that demonstrated that the LDL receptor was not important for the HL-mediated uptake of lipoproteins. Crosslinking experiments confirmed the binding of HL to LRP on the cell surface. To identify the region of HL involved in the interaction with LRP, we used a C-terminal fragment of LpL, known to inhibit LpL-mediated uptake. HL-mediated lipoprotein uptake was suppressed by this fragment. Our experiments indicate that HL, like LpL, can mediate the uptake of lipoproteins into cells, most probably via a C-terminal binding site. The uptake, initiated by proteoglycan binding, is mediated by LRP.

Animals↗
PubMed1996

[The cytochemical observation of inosine effect on glucose metabolism of BGC-823 human gastric carcinoma cell line].

The activity of intracellular lactic acid dehydrogenase (LDH) and succinic acid dehydrogenase (SDH) was studied by cytochemistry in BGC-823 gastric carcinoma cell line treated with inosine. Cytoplasmic granules of LDH were found decreased or completely disappeared, while little change of SDH was observed. The tumor cells were decreased in number and became atrophic, especially when the cells were treated with high concentrations of inosine. The results suggest that inosine can play a role in suppressing the activity of intracellular LDH, thus blocking the major source of energy supply of cancer cells.

Energy Metabolism↗
PubMed1996

[Comprehensive treatment of intracranial aneurysm complicated by postoperative vasospasm].

Forty six patients suffered from intracranial aneurysm complicated by postoperative vasospasm and delayed cerebral ischemia were monitored dynamically both by clinical observation of neurologic status and multiple items such as transcranial Doppler, serum osmolality, intracranial pressure and other somatic physiologic items related to monitoring. Patients were intensively and comprehensively treated according to individualized grading of vasospasm. Forty four patients (95.6%) were completely recovered from postoperative vasospasm and delayed cerebral ischemia, while 2 patients (4.3%) complicated by hemipalsy as a consequence of delayed cerebral ischemia. The occurrence of vasospasm and delayed cerebral ischemia, the criteria of TCD grading, the valuableness of multiple physiologic items and problems related to comprehensive treatment are discussed.

Adult↗
PubMed1996

[Comparison of local antigen-specific IgA responses with serum IgA response after intrapulmonary antigen immunization in healthy subjects].

OBJECTIVE: To observe local lung and serum antigen-specific IgA response after local lung antigen immunization (LLI). METHODS: 11 healthy subjects were immunized with keyhole limpet hemocyanine (KLH) through bronchoscopy. 10-14 days after immunization, IgA responses were obversed in bronchoalveolar lavage fluids (BALF) and serum. RESULTS: LLI induced anti-KLH IgA response in immunized BALF and serum, and both were polymeric IgA. Anti-KLH IgA2/IgA1 ratios were greater in immunized BALF than in serum. Anti-KLH IgA activity in immunized BALF was associated with secretory component (SC), but in serum was not correlated with SC. CONCLUSIONS: LLI could induce local antigen-specific IgA production. There were markedly differences between the structure and subclass distribution of antigen-specific IgA in immunized BALF and serum.

Adjuvants, Immunologic↗