Biomedical subjects

D Li

Publications and source records attributed to D Li.

At least 577 records · Page 32Linked to original sources

PubMed1997

Decreased expression of Kv4.2 and novel Kv4.3 K+ channel subunit mRNAs in ventricles of renovascular hypertensive rats.

Hypertension-induced cardiac hypertrophy is associated with alterations in ventricular action potentials. To understand molecular mechanisms underlying this electrical abnormality, expression of cardiac voltage-gated K+ channel subunit genes was examined in ventricles of renovascular hypertensive rats. While generating a rat Kv4.3 probe, we discovered a previously unreported 19-amino acid insertion in the C-terminal intracellular region of the channel subunit. RNase protection assays indicated that this novel isoform is predominant in rat lung and heart. Effects of renovascular hypertension were then determined by using renal artery clipping models: two-kidney, one clip (2K-1C) rats, a model of high-renin hypertension with a normal plasma volume, and one-kidney, one clip (1K-1C) rats, a model of normal renin with a raised plasma volume. Expression of Kv4.2 and Kv4.3 mRNAs was diminished by > 50% in ventricles of 2K-1C rats; however, no changes in the expression of Kv1.2, Kv1.4, Kv1.5, Kv2.1, or KvLQT1 mRNAs were detected. Similar downregulation of Kv4.2 and Kv4.3 mRNAs was detected in 1K-1C rats. Chronic administration of captopril, an angiotensin-converting enzyme inhibitor, blocked the development of hypertension and the suppression of Kv4 subfamily channel mRNA expression in 2K-1C rats. Furthermore, captopril administration to sham-operated rats significantly increased Kv4.2 mRNA. These results indicate that renovascular hypertension causes specific reductions in Kv4 subfamily channel mRNA expression and that this effect is likely to be mediated primarily by an increase in cardiac afterload.

Alternative Splicing↗

PubMed1997

Corticosteroid reversibility in COPD is related to features of asthma.

Eosinophilic inflammation has been observed in the airways of patients with chronic obstructive pulmonary disease (COPD). A subset of patients clinically diagnosed as having COPD show a reversibility of airflow obstruction when treated with corticosteroids, and may consist of patients with features of asthma including reticular basement membrane thickening and eosinophilic inflammation. Twenty-five unselected patients clinically diagnosed as having COPD received a daily oral dose of 1.5 mg/kg body weight of prednisolone for 15 d to assess the relationships between the functional response to corticosteroids and the presence of features of asthma. Eosinophilic inflammation was characterized before the course of corticosteroid therapy by enumerating eosinophils in peripheral blood, bronchoalveolar lavage fluid (BALF), and bronchial biopsies, using EG2 monoclonal antibody, and by measurement of eosinophil cationic protein (ECP) in BALF. A response to treatment was defined by an increase in FEV1 of at least 12% from baseline values and an absolute value of 200 ml measured at the end of the treatment. Twelve of 25 patients responded to the treatment. By comparison with nonresponders, responders had a significantly larger number of eosinophils (p < 0.015), and higher levels of ECP (p = 0.013) in their BALF. The responders had a thicker reticular basement membrane than the nonresponders (p < 0.04). These results indicate that a response to prednisolone in patients diagnosed as having COPD might occur more readily in a subset of patients presenting with features of asthma.

Adult↗

PubMed1997

Valgus stress radiography in normal ankles.

Deltoid ligament injury is thought to be rare. Signs of complete rupture of the deltoid ligament may be subtle or interpreted as another injury condition and thus are often missed acutely. No standardized method has been created to evaluate medial ligament insufficiency in acute or chronic laxity. To establish a diagnostic test for suspected isolated ruptures of the deltoid ligament, 32 subjects with no previous ankle injury underwent valgus stress radiography and nonstressed radiography of both ankles. Stress radiography in this study showed that there is a measurable but minimal range of talar tilt on valgus stress in previously uninjured ankles. This study provides the basis for diagnosis of the rare isolated rupture of the deltoid ligament of the ankle.

Adult↗

PubMed1997

A Therapeutic Commentary.

ABSTRACT: Thirty-one million patients in the United States undergo surgical procedures every year. Approximately 10%-the majority of these with hypertension-are at an increased risk for perioperative and postoperative cardiovascular morbidity and mortality. Thus, hypertensive patients requiring surgery, especially the 2.1 million undergoing noncardiac procedures, should be evaluated carefully for the magnitude, and if severe, the cause of the hypertension. Additionally, their associated metabolic and cardiovascular status should be characterized and corrected with aggressive therapy. Hypertensive patients with known ischemic heart disease, those with multiple risk factors for ischemic heart disease (IHD), some with valvular heart disease, and those with congestive heart failure should be evaluated for their ability to perform the physical and social activities of everyday life, and, when necessary, have formal stress testing. Most studies suggest that blood pressures of 180/110 mm Hg or greater are associated with a greater risk for perioperative ischemic events. Therefore, the goals of blood pressure control should be to reduce the blood pressure without jeopardizing organ function. Antihypertensive medication should be administered until the time of surgery. beta-Receptor blockers should be instituted or continued in patients with angina and in some patients with congestive heart failure. Those without prior antihypertensive therapy might be best treated with beta-blocker therapy perioperatively as evidenced by the Multicenter Study of Perioperative Research Group with atenolol and those earlier studies with metoprolol. The risks of the surgery should be discussed with the patient so the risks can be weighed against the expected benefit. Studies suggest that perioperative risk for any patient, and especially patients with hypertension, are in part related to the adrenergic arousal before, during, and after the procedure as evidenced by the rise in heart rate and blood pressure, along with the liberation of clotting facators and increased risk for plaque rupture, coronary vasoplasm, and consequent myocardial infarction and fibrosis.

Journal Article↗

PubMed1997

Airway mucosa: secretory cells, mucus and mucin genes.

The airway mucosa is lined by a continuous epithelium comprised of multiple cell phenotypes, several of which are secretory. Secretions produced by these cells mix with a variety of macromolecules, ions and water to form a respiratory tract fluid that protects the more distal airways and alveoli from injury and infection. The present article highlights the structure of the mucosa, particularly its secretory cells, gives a synopsis of the structure of mucus, and provides new information on the localization of mucin (MUC) genes that determine the peptide sequence of the protein backbone of the glycoproteins, which are a major component of mucus. Airway secretory cells comprise the mucous, serous, Clara and dense-core granulated cells of the surface epithelium, and the mucous and serous acinar cells of the submucosal glands. Several transitional phenotypes may be found, especially during irritation or disease. Respiratory tract mucins constitute a heterogeneous group of high molecular weight, polydisperse richly glycosylated molecules: both secreted and membrane-associated forms of mucin are found. Several mucin (MUC) genes encoding the protein core of mucin have been identified. We demonstrate the localization of MUC gene expression to a number of distinct cell types and their upregulation both in response to experimentally administered lipopolysaccharide and cystic fibrosis.

Animals↗

PubMed1997

Eotaxin protein and gene expression in guinea-pig lungs: constitutive expression and upregulation after allergen challenge.

Eotaxin is an eosinophil-specific chemoattractant originally identified in bronchoalveolar lavage fluid after allergen challenge of sensitized guinea-pigs. We have determined and quantified for the first time the cellular sources of guinea-pig lung eotaxin and localized gene expression in structural cells of large and small airways and in alveolar macrophages. We used anti-guinea-pig eotaxin monoclonal and polyclonal antibodies and a complementary ribonucleic acid (cRNA) probe to detect eotaxin protein and cytoplasmic messenger ribonucleic acid (mRNA) transcripts by the techniques of immunohistochemistry and in situ hybridization in: 1) naive; 2) ovalbumin-sensitized/ saline-exposed; and 3) ovalbumin-sensitized/ovalbumin-challenged animals (n = 5 for each group). Compared with the naive animals, there was a fivefold increase of eotaxin protein and a 25 fold upregulation of eotaxin gene expression in the airway epithelium 3 h after ovalbumin challenge of sensitized animals (p < 0.001). The average percentages of alveolar macrophages staining for eotaxin protein and mRNA in the naive animals were approximately 30 and 10% respectively: both increased significantly in the sensitized/ovalbumin-challenged animals to 78 and 57%, respectively (p < 0.0001). Compared with the naive animals, the procedure of sensitization and saline exposure significantly increased eotaxin gene expression in both bronchial epithelium and alveolar macrophages (p < 0.01): the upregulation at these two sites showed a strong positive association (rcorr = 0.95; p < 0.0001). The results indicate that there are multiple cellular sources of guinea-pig lung-derived eotaxin, including bronchial and bronchiolar epithelial cells, airway smooth muscle, bronchial vascular endothelium, and chondrocytes and alveolar macrophages, and that there are relatively rapid and marked increases of eotaxin protein and gene expression in airway epithelium and alveolar macrophages following allergen challenge.

Allergens↗

PubMed1997

The role of interleukin-2 in combination adenovirus gene therapy for head and neck cancer.

Interleukin-2 (IL-2) gene therapy alone and in combination with the herpes thymidine kinase gene (tk) was used to evaluate immunological responses and antitumor effects in head and neck cancer. Established floor of mouth squamous cell carcinomas in C3H/HeJ mice were directly injected with recombinant adenoviral vectors carrying both therapeutic and control genes. One week after adenoviral gene transfer, only the animals treated with combination IL-2+tk or tk alone demonstrated significant tumor regression. Residual tumors were harvested for microscopic evaluation and immunohistochemistry staining, which revealed a predominance of CD8+ lymphocytes in the tumor beds of the animals treated with IL-2. To evaluate the systemic immune effects of IL-2, animals treated with single or combination gene therapy received a second site challenge with parental tumor cells or a heterologous but syngeneic sarcoma cell line. Mice treated with combination IL-2 and tk demonstrated a protective systemic immunity specific to the parental tumor cell line, whereas no systemic immune response was evident in mice receiving IL-2 alone. In a separate experiment, a range of concentrations of the adenovirus IL-2 vector were used to treat established tumors. Even with the maximal single-dose adenovirus concentration, IL-2 alone was ineffective as a single therapy. These results support the use of adenovirus-mediated gene transfer of IL-2 as an effective immunotherapy when used adjuvantly with the tk "suicide gene".

Adenoviridae↗

PubMed1997

Effect of tripterine on collagen-induced arthritis in rats.

AIM: To study the therapeutic effect of tripterine (Tri) on collagen-induced arthritis (CIA). METHODS: Collagen type II (Col) 1.5 mg was injected intradermally to induce CIA in rats. Hind paw volumes of rats were measured with a water displacement method. The serum anti-collagen antibody was measured by an enzyme-linked immunosorbent assay. Delayed hypersensitivity was reflected by skin response to Col. Interleukin-1 (IL-1) and interleukin-2 (IL-2) activities were evaluated by [3H]TdR uptake. Joint was evaluated histologically. RESULTS: Tri 15 and 30 mg.kg-1.d-1 given i.g. to rats 3 d after the first sign of arthritis reduced inflammatory swelling, suppressed humoral and skin response to Col, inhibited IL-2 and IL-1 production, reduced pathological progression of joint. CONCLUSION: Tri has a therapeutic effect on CIA.

Animals↗

PubMed1997

Adrenoceptor agonists inhibit calcium-dependent potentials in rat stellate ganglion neurons.

AIM: To study the effects of adrenoceptor agonists on the stellate ganglion neurons. METHODS: Intracellular recordings were made from neurons of the isolated rat stellate ganglia. RESULTS: Noradrenaline and clonidine (10-30 mumol.L-1) reversibly depressed 3 types of calcium-dependent potentials, namely, the action potential shoulder; the spike after-hyperpolarization; the Ca2+ spike evoked in Krebs' solution containing TTX and TEA and fast excitatory postsynaptic potential (f-EPSP). CONCLUSION: The adrenoceptor agonists inhibitied the 3 calcium-dependent potentials; f-EPSP was inhibited by reducing Ca2+ influx at presynaptic site in population of neurons.

Action Potentials↗

PubMed1997

[An investigation of precipitation of airborne fungi particles in the rooms of university library].

Precipitation of airborne fungi particles in the rooms of an University library and the influencing factors were studied in May 1994 with the fallen plate method. The total average precipitation of airborne fungi particles was 11.68 per dish in 5 minutes. The differences were significant from different room patterns, floors and times, so were the humidity assayed. The book-store rooms and reading rooms had an average precipitation of 15.01 and 8.35 per dish in 5 minutes respectively (P < 0.05), and humidity of 41.7 and 11.4 percent respectively (P < 0.01). The influencing factors were: different floors and room patterns, the people's activity, the different time, humidity, ventilation and book pollution.

Air Microbiology↗

PubMed1997

[A continuous and constant rate administration method--mini-osmotic pump].

Mini-osmotic pump is a delicate administration method. When it is activated by water, mini-osmotic pump can deliver a variety of solutions or suspensions at a constant rate for days even up to several weeks. Since it is drived by osmotic pressure, the pumping rate is independent on the physical and chemical feature of the drugs. The pump from inside to outside consists of a cylindrical reservior, osmotic driving agent and semipermeable membrane.

Animals↗

PubMed1997

[The effect of calcium content in bovine cancellous bone as carrier on expression of tumor necrosis factor-alpha gene in mice].

We investigated the expression of tumor necrosis factor-alpha (TNF alpha) gene in the area of implanted calf cancellous bone with different calcium content and the influence of calcium salts on local cellular immunity. The particles of mineralized and partially demineralized bone were implanted in the mouse's muscle pouch, and removed 3, 5, 10 and 20 days after implantation of the bone particles. The specimens were processed for determining the expression of mRNA encoding TNF alpha, which was performed by a nonradioactive in situ hybridization technique. The expression of TNF alpha mRNA was markedly higher in the mineralized bone group than in the partially demineralized bone group (P < 0.01). The positive rate of TNF alpha gene expression was highest by 10 days after implantation. There was a strong hybridization signal localization to the cytoplasm of morphologically identifiable monocytes and multinucleated giant cells. Similar activity was detected in the cytoplasm or nuclei of mesenchymal cells, fibroblasts as well as striated muscle fibers. This finding suggests that the calcium content in calf cancellous bone possesses a significantly stimulative effect on TNF alpha mRNA expression, and calcium salts may be of importance for the modulation of local cellular immunity.

Animals↗

PubMed1997

[Macro, micro and ultrastructural observations of pituitary, adrenal, pancreas and spleen in experimental brain death].

The purpose of this study is to observe the macro, micro and ultrastructural changes of the pituitary, adrenal, pancreas and spleen in the experimental primary brain death. The results showed: 1. acinar zymogen granule of pancreas decreased, karyopyknosis of islet cells formed. 2. dilation and blood stasis of spleen sinus happened 3. adrenocortical karyopyknosis formed, mitochondrial crista vanish. 4. Pituitary karyopyknosis and cytolysis developed. 5. there was correlation between the extent of lesions and time after brain death.

Adrenal Glands↗

PubMed1997

[The relationship between the prognosis of retinoblastoma and proliferating cell nuclear antigen and argyrophilic protein at nucleolus organizer regions].

OBJECTIVE: To investigate the relationship between the proliferative activity of retinoblastoma (Rb) cells and the prognosis of the tumor. METHODS: Proliferating cell nuclear antigen (PCNA) and argyrophilic nucleolar organizer regions (AgNORs) in paraffin-embedded Rb specimens from 48 cases were detected by LSAB immunohistochemical method using an anti-PCNA monoclonal antibody and the technique of ploton. RESULTS: The PCNA labeling index (PCNALI) and the AgNORs counts were well correlated (r = 0.647, P < 0.001). In 29 patients of the 48 cases receiving simple eyeball extirpation and being followed up for 5 years, the mean PCNALI and the mean numbers of AgNORs per nucleus in 19 patients surviving > or = 5 years after operation were markedly lower than that in 10 patients surviving < 5 years after operation (P < 0.01, P < 0.05). CONCLUSION: It is indicated that the PCNALI or the AgNOR count is negatively related with the clinical prognosis of Rb patients, and can be useful in judging the prognosis.

Eye Enucleation↗

PubMed1997

[Experimental study of prostacyclin on the survival of random skin flaps].

The purpose of this experiment was to observe the effect of PGI2 on the survival of the random skin flap. White rats used in the experiment were divided into preoperation (prevention) group, postoperation (treatment) group and the control group. A super-long random skin flap was created on the back of the animal. Postoperatively, the treatment group received intravenous injection of PGI2 while the control group received intravenous injection of normal saline. The blood supply, metabolism and hemorheology of the flap were analyzed. Results showed that the relative blood flow on the distal part of the flap was 41.3% in the treatment group and 22.4% in the control group. The survival rate of the flap of the treatment group was higher than that of the control. There were no differences between the prevention and the control groups. It is concluded that early postoperative injection of PGI2 could improve blood supply and rheology of the flap and increase its survival rate.

Animals↗

PubMed1997

[The application of dental stents in implant therapy].

The improperiety of the location of implants would cause many difficulties to prosthetic procedure. The function, appearance and long-term health of implant denture would then be effected. Dental stents were used to resolve the above problems for 30 cases of implant denture involved 74 implants in present study. A radiographic stent with given diameter sphere can be used to eliminate distortion and determine the bone quantity. A surgical stent can express the prosthetic plan to surgeons during operation directly in the mouths of patients. It is very helpful to the surgeons to take account of both the condition of jaw bone and the future denture making. Holes, tunnels and windows on surgical stents can be used as the guidances of drilling positions and directions. The surgical stents may also be a useful reference to surgeons to make bone graft, do some changes in surgical plan and even cancel the implant denture therapy when the situation of jaw bone significantly differ from what the expectancy.

Dental Implantation, Endosseous↗

PubMed1997

[Primary curative incision in the treatment of perianorectal abscess].

More than 50% of the patients with perianorectal abscess treated with traditional incisional drainage will lead to fistula formation postoperatively. We present a procedure of primary curative incision for treatment with perianorectal abscess without fistula formation. The result of primary curative incision in comparison with traditional incisional drainage in a randomized control study showed that the incidence of postoperative fistula formation and recurrent abscess was 2.56% in the former and 56.25% in the latter. The key points of the procedure were discussed in detail and the causes and prevention of the disease occurred after injection of sclerotic drugs for hemorrhoids were also discussed.

Abscess↗

PubMed1997

[Inherent mdr-1 gene expression in fresh tumor tissue specimens from several high-incidence malignancies].

OBJECTIVE: To ascertain frequency of inherent mdr-1 gene expression in several common neoplasms. METHODS: One hundred fifty one surgically resected tumor specimens confirmed pathologically to be malignant from preoperatively untreated cancer patients were studied. Expression of mdr-1 gene was examined by RT-PCR. RESULTS: The frequency of primary mdr-1 gene expression was 33.3% for cancer of the stomach and gastric cardia (17/51), 37% for cancer of the esophagus (17/46), 31.3% for cancer of the colon and rectum (5/16), 13.2% for cancer of the breast (2/15), 40.0% for cancer of the thyroid (4/10), 55.0% for cancer of the lung (5/9) and 0% for cancer of the uterine cervix (0/4). CONCLUSION: Primary mdr-1 gene expression is relatively of frequent occurrence as detected by RT-PCR technique.

Adenocarcinoma↗