Biomedical subjects

H Lin

Publications and source records attributed to H Lin.

At least 181 records · Page 10Linked to original sources

PubMed1999

Electronic transmission properties in a mesoscopic necklace with inhomogeneous magnetic flux.

The electronic transmission properties and the energy spectrum of a mesoscopic necklace with inhomogeneous flux is calculated. We found interesting transmission behavior that is quite different from the case with homogenous flux. In this model, the transmission depends on both the modulation mode and the amplitude of the flux. The electronic transmission properties can be explained from the energy spectrum of the system.

Journal Article↗

PubMed1999

Shock wave-inertial microbubble interaction: methodology, physical characterization, and bioeffect study.

A method of generating in situ shock wave-inertial microbubble interaction by a modified electrohydraulic shock wave lithotripter is proposed and tested in vitro. An annular brass ellipsoidal reflector (thickness = 28 mm) that can be mounted on the aperture rim of a Dornier XL-1 lithotripter was designed and fabricated. This ring reflector shares the same foci with the XL-1 reflector, but is 15 mm short in major axis. Thus, a small portion of the spherical shock wave, generated by a spark discharge at the first focus (F1) of the reflector, is reflected and diffracted by the ring reflector, producing a weak shock wave approximately 8.5 microseconds in front of the lithotripter pulse. Based on the configuration of the ring reflector (different combinations of six identical segments), the peak negative pressure of the preceding weak shock wave at the second focus (F2) can be adjusted from -0.96 to -1.91 MPa, at an output voltage of 25 kV. The preceding shock wave induces inertial microbubbles, most of which expand to a maximum size of 100-200 microns, with a few expanding up to 400 microns before being collapsed in situ by the ensuing lithotripter pulse. Physical characterizations utilizing polyvinylidene difluoride (PVDF) membrane hydrophone, high-speed shadowgraph imaging, and passive cavitation detection have shown strong secondary shock wave emission immediately following the propagating lithotripter shock front, and microjet formation along the wave propagation direction. Using the modified reflector, injury to mouse lymphoid cells is significantly increased at high exposure (up to 50% with shock number > 100). With optimal pulse combination, the maximum efficiency of shock wave-induced membrane permeabilization can be enhanced substantially (up to 91%), achieved at a low exposure of 50 shocks. These results suggest that shock wave-inertial microbubble interaction may be used selectively to either enhance the efficiency of shock wave-mediated macromolecule delivery at low exposure or tissue destruction at high exposure.

Acoustics↗

PubMed1999

Antifungal properties and target evaluation of three putative bacterial histidine kinase inhibitors.

Histidine protein kinases have been explored as potential antibacterial drug targets. The recent identification of two-component histidine kinases in fungi has led us to investigate the antifungal properties of three bacterial histidine kinase inhibitors (RWJ-49815, RWJ-49968, and RWJ-61907). All three compounds were found to inhibit growth of the Saccharomyces cerevisiae and Candida albicans strains, with MICs ranging from 1 to 20 microg/ml. However, deletion of SLN1, the only histidine kinase in S. cerevisiae, did not alter drug efficacy. In vitro kinase assays were performed by using the Sln1 histidine kinase purified from bacteria as a fusion protein to glutathione S-transferase. RWJ-49815 and RWJ-49968 inhibited kinase a 50% inhibitory concentration of 10 microM, whereas RWJ-61907 failed to inhibit at concentrations up to 100 microM. Based on these results, we conclude that these compounds have antifungal properties; however, their mode of action appears to be independent of histidine kinase inhibition.

Antifungal Agents↗

PubMed1999

Adenovirus-mediated expression of a ribozyme to c-myb mRNA inhibits smooth muscle cell proliferation and neointima formation in vivo.

Smooth muscle cell (SMC) proliferation is an important component of restenosis in response to injury after balloon angioplasty. Inhibition of proliferation in vivo can limit neointima hyperplasia in animal models of restenosis. Ribozymes against c-myb mRNA have been shown to be effective inhibitors of SMC proliferation in vitro. The effectiveness of adenovirus as a gene therapy vector in animal models of restenosis is well documented. In order to test the utility of ribozymes to inhibit SMC proliferation by a gene therapy approach, recombinant adenovirus expressing ribozymes against c-myb mRNA was generated and tested both in vitro and in vivo. This adenovirus ribozyme vector is shown to inhibit SMC proliferation in culture and neointima formation in a rat carotid artery balloon injury model of restenosis.

Adenoviridae↗

PubMed1999

Somatic signaling mediated by fs(1)Yb is essential for germline stem cell maintenance during Drosophila oogenesis.

Drosophila oogenesis starts when a germline stem cell divides asymmetrically to generate a daughter germline stem cell and a cystoblast that will develop into a mature egg. We show that the fs(1)Yb gene is essential for the maintenance of germline stem cells during oogenesis. We delineate fs(1)Yb within a 6.4 kb genomic region by transgenic rescue experiments. fs(1)Yb encodes a 4.1 kb RNA that is present in the third instar larval, pupal and adult stages, consistent with its role in regulating germline stem cells during oogenesis. Germline clonal analysis shows that all fs(1)Yb mutations are soma-dependent. In the adult ovary, fs(1)Yb is specifically expressed in the terminal filament cells, suggesting that fs(1)Yb acts in these signaling cells to maintain germline stem cells. fs(1)Yb encodes a novel hydrophilic protein with no potential signal peptide or transmembrane domains, suggesting that this protein is not itself a signal but a key component of the signaling machinery for germline stem cell maintenance.

Animals↗

PubMed1999

[A study on mutation of exon 5 of presenilin-1 in Alzheimer's disease].

OBJECTIVE: To explore the role of the mutation of presenilin-1 in pathogenesis of sporadic Alzheimer's disease. METHODS: The exon 5 of presenilin-1 was analysed by using polymerase chain reaction- single strand conformation polymorphism (PCR-SSCP) and ABI 310 genetic analyzer technique in 68 patients with Alzheimer's disease and 65 normal controls. RESULTS: A mobility shift of SSCP in exon 5 of presenilin-1 was detected in 4 patients with Alzheimer's disease;two missense mutations were found. One mutation was at Leu 130 Met and the other at Val157 Leu. Another mobility shift of SSCP in exon 5 of presenilin-1 was detected in 11 patients with Alzheimer's disease. One missense mutation was at Leu 130 Met and one same sense mutation C462-->T. But no mobility shift of SSCP was found in patients with vascular dementia and in normal controls. CONCLUSION: The authors found that mutations in exon 5 of presenilin-1 also existed in patients with sporadic Alzheimer's disease, which might be one of the points of mutations in sporadic Alzheimer's disease in Chinese.

Aged↗

PubMed1999

[An investigation of small marker chromosome in eight Turner syndrome patients by fluorescence in situ hybridization and DNA analysis].

OBJECTIVE: To direct genetic counseling and identify the origin of small marker chromosome in patients with Turner syndrome stigmata. METHODS: The specific primer on the sex determining region on Y (SRY) and biotin labeled X- and Y-chromosome DNA probes were utilized in the analysis of sex chromosome-derived markers. The PCR product from the amplification was detected on agarose gel, and fluorescence in situ hybridization (FISH) was conducted to metaphase chromosome. RESULTS: In 8 patients who had a small marker chromosome, five markers were derived from the X chromosome and three from the Y chromosome. Two patients with a Y-derived marker were determined by Y-chromosome probe as well as by SRY sequences amplification. One patient with a Y-derived marker was only demonstrated by FISH. CONCLUSION: The findings of this study demonstrate successfully the value and necessity of FISH utilizing DNA probes combined with specific amplification on SRY gene in the identification of sex chromosome marker. Such identification is important not only for clinical care, but also for understanding phenotype-karyotype correlations.

DNA-Binding Proteins↗

PubMed1999

Clinical implication of atypical squamous cells of undetermined significance with or without favoring high-grade squamous intraepithelial lesion on cervical smears.

BACKGROUND: The cytologic diagnosis of atypical squamous cells of undetermined significance (ASCUS) on a cervical smear usually makes clinicians unsure of how to manage the patient and follow-up on her condition. We attempted to define the clinical implication of qualifying the cytologic diagnosis of ASCUS as either favoring a high-grade squamous intraepithelial lesion (HSIL) or not in an effort to provide management guidelines. METHODS: From January through May 1997, 65 of 5792 women who had cervical/vaginal smears taken at Kaohsiung Chang Gung Memorial Hospital were diagnosed as having ASCUS. Thirteen of the 65 cases of ASCUS favored an HSIL, based on nuclear abnormalities in atypical metaplastic and parakeratotic-type squamous cells. All these 65 patients were evaluated in our outpatient clinic by a second cervical smear, colposcopy, and colposcopically directed biopsies and/or endocervical curettage. The median length of the follow-up period was 19 months (range, 16 to 21 months). RESULTS: Of the 52 patients evaluated for ASCUS smears without favoring HSIL, 6 (11.5%) had a low-grade SIL (LSIL), 1 (1.9%) had cervical intraepithelial neoplasia grade II (CIN II), and 1 (1.9%) had invasive squamous carcinoma. Of the 13 patients with a cervical cytologic diagnosis of ASCUS favoring HSIL, 1 (7.6%) had immature metaplasia, 2 (15.4%) had LSIL, 2 (15.4%) had CIN II, 6 (46.2%) had CIN III, and 2 (15.4%) had invasive squamous carcinoma. CONCLUSION: For patients with a cytologic diagnosis of ASCUS favoring HSIL, more aggressive interventions, such as colposcopy-directed biopsy, endocervical curettage, or even conization, should be performed promptly. However, those without features favoring HSIL may be evaluated with regularly repeated smears.

Female↗

PubMed1999

Effect of benzene, toluene, xylene on the semen quality of exposed workers.

OBJECTIVE: To examine the effects on semen and sperm quality of workers after a short and long term exposure to benzene, toluene, and xylene. METHODS: The semen and blood of 24 married workers exposed to benzene, toluene, and xylene from shoemaking, spray painting, or paint manufacturing factories were collected. The concentration of benzene, toluene, and xylene in the blood and semen was determined by using headspace chromatographic method. Routine sperm test was carried out and acrosin activity detected. RESULTS: The results showed that benzene, toluene, and xylene were found in the blood and semen of some ex-workers in a working environment where the air concentration of benzene, toluene, and xylene exceeded the maximum allowable concentration (MAC). This result was not found in workers of the control group. There were also some effects on the quality of semen in the exposed workers. For example, the percentage of semen with liquefaction time exceeding 30 minutes increased. The sperm vitality, motility and acrosin activity decreased. At the same time, there were a positive correlation between liquefaction time and the level of toluene in semen, and a negative correlation between sperm vitality, sperm activity or acrosin activity and working history. CONCLUSIONS: The results suggested that the mixture could affect the quality of semen and sperm, which might be the main reason of the abnormal pregnancy outcome among the wives of workers exposed to benzene, toluene, and xylene. Further studies are, however, required to confirm these findings.

Acrosin↗

PubMed1999

[Effects of hypotension induced by isoflurane on hemodynamics and plasma beta 2 microglobulins and creatinine during cerebral aneurysm operation].

OBJECTIVE: To investigate the effects of isoflurane-induced hypotension on the hemodynamics and the changes of plasma beta 2 microglobulins and creatine during cerebral aneurysm operation. METHODS: Thirty-two cerebral anuerysm patients were operated under general anesthesia. Anesthesia was induced with droperidol, fentayl, sodium pentothal and pavolon intravenously. After tracheal intubation, the isoflurane was inhalated to maintain anesthesia. The concentration of isoflurane was elevated to reduce MAP by 30%-40% during dissection and occlusion of tumor and the level maintained for 30-45 min. Hemodynamic values were measured with Swan-Ganz technique. The hemodynamic parameters(CO, CI, SV, SI, SVR, LVSWI, RVSWI, CVP, CPP, RPP and HR) which were measured with Swan-Ganz technique before, during and after isoflurane-induced hypotension were compared. Blood samples were drawn in given time intervals to determine the concentration of plasma beta 2 Microglobulins(beta 2 MG) by radioimmunoassay. Changes in hemodynamics and the plasma beta 2 MG and creatinine (Cr) after deliberate hypotension of isoflurane were recorded at the same time. RESULTS: No significant changes of CO, CI, SV, SI, RVSWI, CVP, HR and ECG tracing were observed during hypotension (P > 0.05). SVR, PVR, LVSWI, Cpp and Rpp were significantly decreased during hypotension (P < 0.05), but the risk of myocardial ischemia and deoxygenation was not increased. No effect was found on the plasma beta 2 MG and Cr during isoflurane-induced hypotension in patients undergoing cerebral aneurysm cling operation. CONCLUSION: Hypotension induced by isoflurane during cerebral aneurysm operation is able to keep a good balance of myocardial oxygen delivery and consumption, and keep a good myocardial function.

Creatinine↗

PubMed1999

[Oxygen utilization coefficient in predicting the severity of critical illness].

OBJECTIVE: To evaluate the role of oxygen utilization coefficient (O(2)UC ) in predicting the severity of various diseases. METHODS: Gas analysis of arterial blood and central venous blood and calculation of O(2)UC [O(2)UC = (SaO(2) - SvO(2))/SaO(2)] were carried out in different groups (group 1, 16 cases of trauma, all survived; group 2, 18 emergency cases undergoing cardiopulmonary resuscitation(CPR); group 3, 13 cases undergoing CPR in intensive care unit, all died; group 4, 13 critically ill patients. RESULTS: O(2)UC was 0.30 +/- 0.08, 0.67 +/- 0.27 and 0.60 +/- 0.15 in the groups 1, 2 and 3 respectively. The difference between group 1 and 2 was significant (P < 0.001). O(2)UC persisted to increase, and maintained high for a long time (more than 8 approximately 12 hours), the prognosis of the patients was bad. The critical limitation of O(2)UC was 0.40. In group 4 O(2)UC was closely correlated with the severity of clinical condition. CONCLUSION: O(2)UC is a convenient, reliable and sensible predictor in the treatment of critically ill patients.

Adolescent↗

PubMed1999

[Expression of interleukin-6 and its receptors in peripheral blood of patients with systemic lupus erythematosus].

OBJECTIVE: To investigate the level of interleukin-6 (IL-6) and soluble-IL-6 receptor (sIL-6R) in serum of patients with systemic lupus erythematosus (SLE) and its correlation with disease activity and to explore IL-6 signal transduction pathways in SLE patients. METHODS: By using MTT colorimetry and ELISA, the levels of IL-6 and sIL-6R in serum from 16 patients with SLE (9 active, 7 inactive), 17 with active rheumatoid arthritis (RA) and 29 controls were measured. The expressions of acute phase reaction factor (APRF) in peripheral blood mononuclear cells (PBMCs) were also detected by using electrophoresis mobility shift assays (EMSA) after the PBMCs were isolated and then stimulated by IL-6. RESULTS: Serum IL-6 and sIL-6R levels in active SLE patients were significantly higher than those in normal controls (P < 0.01), but were significantly lower than those in active RA patients (P < 0.01). Serum IL-6 rather than sIL-6R level in active SLE patients was significantly higher than that in inactive ones (P < 0.01). Serum IL-6 was correlated positively with the anti-dsDNA antibody (r = 0.658, P < 0.01), but not with CRP (r = 0.041, P > 0.05). There were no expression of APRF in PMNC from SLE patients and 8 normal controls, whereas PMNC from 11 RA patients expressed APRF activity (11/17). CONCLUSION: The level of IL-6 is a useful parameter for monitoring disease activity of SLE. In active SLE, no significant elevation of serum sIL-6R and no expression of APRF in PMBCs may be responsible for mild CRP elevation.

Adolescent↗

PubMed1999

[A study on expressions of P53 protein and proliferating cell nuclear antigen in malignant eyelid tumors].

OBJECTIVE: To observe the relationship between P53 gene mutation and malignant eyelid tumor. METHODS: The expressions of P53 protein and proliferating cell nuclear antigen (PCNA) in 102 cases with malignant eyelid tumors were examined by labelled streptravidin biotin (LSAB) immunohistochemical technique. RESULTS: Although overexpression of P53 protein was not detected in normal eyelid cutaneous epithelium, meibomian gland and mild epithelial dysplasia, the positive rate of P53 increased in degree in moderate and severe dysplasia, carcinoma in situ and invasive tumors, and PCNA labeling index (PI) progressively increased too. Overexpression of P53 protein was detected in 30/53 cases of basal cell carcinoma (BCC), 16/32 cases of squamous cell carcinoma (SCC), 10/17 cases of meibomian gland carcinoma, and the intensity of P53 protein immunostaining increased with the lowering in the degree of histological differentiation. The mean PCNA labeling index was 38.1 +/- 31.1, 38.3 +/- 30.1, 42.6 +/- 32.0 respectively in BCC, SCC and meibomian gland carcinoma. The PI value in tumor tissue with positive P53 protein expression was higher than that in tissues with its negative expression (P < 0.05). CONCLUSIONS: The gene mutation of P53 protein might play an important role in the pathogenesis of malignant eyelid tumors, it may be one of the factors that can lead to abnormal hyperactivity of cell proliferation and it possibly can be a malignant sign in the progression of a tumor.

Aged↗

PubMed1999

[Studies on DNA single strand breaks induced by sodium nitroprusside-nitric oxide donor].

OBJECTIVE: To study the effect of sodium nitroprusside (SNP), a nitric oxide (NO) donor, on DNA single strand breaks (SSBs). METHODS: A modified method was used to isolate and prepare the single cell suspension from the organs of mice. Alkaline single-cell gel electrophoresis (SCGE) was performed to examine DNA damage of the cells treated by SNP in vivo and in vitro. RESULTS: Treatment with 0.5 - 2.0 micromol/ml of SNP with S(9) for 1 h induced a concentration-dependent increase in DNA SSBs in g12 cells. Significant increase in DNA migration and comet frequency in the spleen, thymus and peritoneal macrophage were induced after intraperitoneal injection of SNP at a dose of 0.67 - 6.0 mg/kg. No obvious increase in DNA single strand breaks was observed in the liver, kidney and lung of the mice with same treatment. CONCLUSION: DNA SSBs could be induced by NO in some cells in vivo and in vitro. There was difference in sensitivity of various organs in the mice to NO. Cells of spleen and thymus and macrophage may be the important target cells of NO.

Animals↗

PubMed1999

[The amyloidosis in cardiac conduction system].

OBJECTIVE: To investigate the relationship between arrhythmia, cardiac failure and amyloidosis of cardiac conduction system (CCS). METHODS: CCS from 6 cases with cardiac amyloidosis were sampled using technique designed by the authors. The CCS were studied by Congo red staining and polarization microscopy. RESULTS: Pathological changes could be found in the CCS of these 6 cases. It was serious in sino-atrial node while slight in atrio-ventricular conduction system. The changes in atrio-ventricular conduction system were exacerbated from proximal part (atrio-ventricular node) to distal part (left bundle branch). In the 3 cases with sinus bradycardia and conduction blocking manifested by electrocardiogram, the pathological changes in CCS were more extensive and serious than that of other cases. CONCLUSION: The amyloidosis in CCS is one of the pathological bases of arrhythmia.

Aged↗

PubMed1999

[Mechanism study of muscle injury from high tension (I)--The biomechanical effect of training on muscle injury from downhill running in rats].

In this experiment, we tested the biomechanical characteristics of rat's fast and slow skeletal injury from downhill running at different times. The result indicates that the mechanical properties of fast and slow skeletal muscle, including maximum tensile strength, maximum strain, elasticity and energy absorption, gradually stregthen with extended time (not more than 48 hours) after eccentric exercise-induced injury. On the other hand, the maximum strain of slow muscle is higher than that of fast muscle.

Animals↗

PubMed1999

[Variations of the middle meatus mucosa ultrastructure after endoscopic sinus surgery].

OBJECTIVE: To explore the variations of middle meatus ultrastructure after endoscopic sinus surgery. METHOD: 10 cases whose middle meatus mucosa recovered well after undergoing endoscopic sinus surgery were screened, and postoperative electron microscope examinations of middle meatus mucosa were made in the first, second, third and forth month. RESULT: In the first month after operation, there was obvious fibre proliferation in the mucosa. In the second month, there was fibre proliferation and dissolution existing simultaneously. In the third month, the mucosa's structure resumed fundamentally to normal, but its function was not perfect. In the forth month, the mucosa was completely normal and can function normally. CONCLUSION: The mucosa of middle meatus can resume completely after endoscopic sinus surgery but need at least four months. It is very important to have a long time reexamination for improving therapeutic effect.

Adult↗

PubMed1998

Application of magnetic field-induced heat shock protein 70 for presurgical cytoprotection.

To develop an alternative to hyperthermia for the induction of hsp70 for presurgical cytoprotection, we investigated the optimal exposure conditions for magnetic field induction of hsp70. Normal human breast cells (HTB124) were exposed to 60-Hz magnetic fields and hsp70 levels were measured following three different exposure conditions: continuous exposure up to 3 h, a single 20-min exposure, and a single 20-min exposure followed by repeated 20-min exposures at different field strengths. In cells exposed continuously for 3 h, hsp70 levels peaked (46%) within 20 min and returned to control levels by 2 h. Following a single 20-min exposure, the return of hsp70 levels to control values extended to more than 3 h. When cells underwent a 20-min exposure followed by repeated 20-min exposures (restimulation) with different field strengths, additional increases in hsp70 levels were induced: 31% at 1 h, 41% at 2 h, and 30% at 3 h.

Breast↗