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Biomedical subjects

L Bin

Publications and source records attributed to L Bin.

14 recordsLinked to original sources
PubMed2001

Optimal ECG trigger point in electron-beam CT studies: three methods for minimizing motion artifacts.

RATIONALE AND OBJECTIVES: The authors hypothesized that electrocardiographic triggering near end systole could minimize motion artifacts in electron-beam computed tomography (CT) of the coronary artery. MATERIALS AND METHODS: The study included 2,660 patients who underwent coronary artery calcium scanning with electron-beam CT. Trigger times were as follows: end of T wave, 120 to 25 msec before end of T wave, 25-50 msec after end of T wave, 40%, 45%, 50%, 55%, 60%, 70%, 75%, 80%, 90%, and 100% of R-R interval. The authors divided each group into seven subgroups according to heart rate. The percentages of cases with motion artifact in the right coronary artery were computed. Optimal trigger times were defined for each group, as well as for scan acquisitions of 250 and 200 msec. RESULTS: The optimal trigger times were as follows for heart rates of less than 50, 51-60, 61-70, 71-80, 81-90, 91-100, and more than 100 beats per minute, respectively: for 100-msec scans, 359 (27% of the R-R interval), 228 (31%), 314 (34%), 304 (38%), 289 (41%), 283 (45%), and 274 msec (48%) after the R wave; for 250-msec scans, 840 (63%), 654 (60%), 240 (26%), 224 (28%), 219 (31%), 208 (33%), and 200 msec (35%) after the R wave; and for 200-msec scans, 722 (65%), 687 (63%), 249 (27%), 248 (31%), 244 (35%), 233 (37%), and 223 msec (39%) after the R wave. CONCLUSION: The use of these new electrocardiographic triggers before end systole yielded the lowest percentage of motion artifacts (<3% across all heart rates), much lower than for conventional triggers (51% of cases with motion artifact for 80% trigger, P < .001).

Artifacts↗
PubMed2001

The retrieval effectiveness of medical information on the web.

The World Wide Web has become such an extensive health information repository in the world that it is increasingly difficult to search for relevant medical information. Many search tools have been developed to help users look for relevant health information on the web, but most of them are still not efficient. In this paper, we discuss some available on-line solutions to medical information retrieval and compare the performances of some general and medicine-specific search engines with the MediAgent, which has been developed by the National University of Singapore (NUS) Medical Informatics Programme. Although a number of medicine-specific searching techniques have been developed, the difficulty of finding medical information still remains because medical search engines are generally not as effective as generic search engines. Different from other search tools, MediAgent's efficiency was quite high, taking only an average of 1.5 links to retrieve the answers, but its retrieving effectiveness is not good enough due to the short period of operation. Whilst the MediAgent project cannot claim to have all the solutions, it nevertheless offers a new alternative to system implementation. New techniques need to be explored in order to overcome the issues of medical information retrieval on the Internet.

Humans↗
PubMed2001

Molecular cloning and characterization of NAG-7: a novel gene downregulated in human nasopharyngeal carcinoma.

OBJECTIVE: To identify novel tumor suppressor genes at chromosome 3p24-26 in human nasopharyngeal carcinoma (NPC). METHODS: Twenty epithelial-derived expressed sequence tags (EST) were selected from chromosome 3p24-26. RT-PCR and Northern blot were used to detect the expression of the ESTs in NPC cell line, HNE-1, and primary cultures of normal nasopharyngeal epithelial cells. One EST, which was substantially downregulated in the HNE-1 cell line, was detected in 19 NPC biopsy samples. cDNA library screening was used to get its full sequence and the sequence of this novel gene was analyzed. RESULTS: A novel gene located at chromosome 3p25.3 was obtained and named NAG-7. It was downregulated in 26.3% (5/19) of NPC biopsy samples. Its 1677 bp full length cDNA had a potential open reading frame predicting a 94 amino acid protein with a molecular weight of 11,023.87 Dalton. Analysis of the NAG-7 gene showed that it was a transmembrane protein containing a protein kinase C phosphorylation site and a myristyl site. It has no significant homology to any reported genes in the database of GenBank. CONCLUSION: NAG-7 is a novel gene downregulated in NPC, suggesting that it may be involved in the development of NPC.

Amino Acid Sequence↗
PubMed2000

Preview method for electron-beam CT scanning of the coronary arteries.

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate a method that uses electron-beam computed tomography to obtain the most appropriate starting level for complete imaging of the coronary tree and to compare it with the existing method. A second aim was to evaluate the spatial location of the coronary arteries relative to different anatomic cardiac and chest landmarks. MATERIALS AND METHODS: Two hundred forty consecutive patients were randomly assigned to imaging with either a six-level preview (new) method or the traditional preview method. The accuracy of each preview method to encompass the coronary anatomy was compared. RESULTS: All coronary arteries were included in 3-mm scans obtained starting three levels above the origin of the left main coronary artery. The left anterior descending coronary artery extended 3-9 mm above the left main artery in 33 patients (14%). The coronary arteries were encompassed by scans depicting 72-105 mm; thus, with 3-mm sections, up to 35 scans are necessary to cover the entire coronary tree. No stable relationship between the coronary arteries and the pulmonary artery or carina could be found. CONCLUSION: The six-level preview method that identifies the left main coronary artery and begins 9 mm above this level is the most accurate method for depicting the coronary anatomy. No anatomic landmarks in the heart or chest can be used reliably to identify the position of the coronary arteries in individual patients.

Coronary Angiography↗
PubMed1999

cDNA representational difference analysis of differentially expressed cDNA sequences in human nasopharyngeal carcinoma.

OBJECTIVE: To search differentially expressed sequences correlated with pathogenesis of human nasopharyngeal carcinoma (NPC), including the candidates of tumor suppressor genes. METHODS: Representational difference analysis (RDA) was performed to isolate differentially expressed sequences between cDNA from normal human primary cultures of nasopharyngeal epithelial cells and cDNA from NPC cell line HNE1. The source of differentially expressed products were proved by Southern blot, Northern blot and in situ hybridization. The fragments were cloned with pGEM-T easy kit and sequenced by the chain termination reaction. RESULTS: Four differentially expressed cDNA fragments were isolated in the fourth subtractive hybridization using cDNA from normal human nasopharyngeal epithelial cells as tester amplicon and cDNA from NPC cell line HNE1 as driver amplicon by cDNA RDA. These differential cDNA fragments revealed that they really came from the tester amplicon and were not expressed or down-regulated in the NPC HNE1 cells. Some of the genes were expressed only in human nasopharyngeal epithelial cells but deleted or down-regulated in the biopsies of NPC. Of these obtained clones, some were the sequences of the human known genes including house-keeping genes, the others represented novel gene sequences. CONCLUSION: The differentially expressed products including the candidates of tumor-suppressor genes may be associated with the initiation of the NPC.

DNA, Complementary↗
PubMed1999

[The expression in situ of transforming growth factor beta s, their receptors and TGF beta-receptor interacting protein-1 in nasopharygneal carcinoma].

OBJECTIVE: To study the expression of transforming growth factor(TGF) beta s, their receptors and TGF beta-receptor interacting protein-1 (TRIP-1) in nasopharygneal carcinoma. METHODS: Immunohistochemical technology and in situ hybridization methods were adopted to detect the TRIP-1 mRNA and 3 kinds of TGF beta isoforms and 2 kinds of TGF beta receptors protein in the same biopsy specimen. RESULTS: The positive expression of TGF beta 1, TGF beta 2, TGF beta 3, TGF beta R I and TGF beta R II was stronger in the tumor adjacent epithelium than in the tumor itself, which were 65.79%, 66.67%, 55.26%, 48.57% and 63.16% higher than those in the tumor itself respectively(P < 0.01). The level of TRIP-1mRNA measured in the epithelial cells was also higher than that in the tumor cells (19.32 +/- 10.70 versus 11.96 +/- 5.85, P < 0.05). CONCLUSION: The signal transmission of TGF beta family is diminished in the poorly differentiated squamous cell carcinoma of nasopharynx. It may be a factor for the development of nasopharygneal carcinoma.

Carcinoma, Squamous Cell↗
PubMed1998

Prostate cancer screening and beliefs about treatment efficacy: a national survey of primary care physicians and urologists.

PURPOSE: To describe practice patterns and beliefs of primary care physicians and urologists regarding early detection and treatment of prostate cancer. SUBJECTS AND METHODS: National probability samples of primary care physicians (n=444) and urologists (n=394) completed mail survey instruments in 1995. Physicians were asked about their use of prostate-specific antigen (PSA) testing for men of different ages and their beliefs about the value of radical prostatectomy, external-beam radiation therapy, and watchful waiting for men with differing life expectancies. RESULTS: Most primary care physicians report doing PSA tests during routine examination of men older than 50 years of age. The majority say they continue to do them on patients over 80 years and to refer men with abnormal values for biopsy. In contrast, only a minority of urologists would recommend PSA tests or biopsy for abnormal values for men over 75 years of age. More than 80% of primary care physicians and urologists doubt the value of radical prostatectomy for men with < 10 years of life expectancy; more primary care physicians than urologists see probable survival benefit in radiation therapy for patients with life expectancy < 10 years (48% versus 36%) or > 10 years (67% versus 53%). Thirteen percent of primary care physicians and only 3% of urologists consider watchful waiting to be as appropriate as aggressive therapy for men with > 10 years of life expectancy. CONCLUSIONS: Primary care physicians are more aggressive about PSA testing and referral for biopsy than most urologists recommend. Both groups recommend PSA testing and believe that aggressive treatment is more beneficial than existing evidence indicates.

Adult↗
PubMed1997

A nationwide survey of practicing urologists: current management of benign prostatic hyperplasia and clinically localized prostate cancer.

PURPOSE: Our aim was to define the spectrum of urological care for benign prostatic hyperplasia (BPH) and clinically localized prostate cancer. MATERIALS AND METHODS: In 1995 a random sample of 394 American urologists was surveyed with a response rate of 67%. RESULTS: Respondents reported seeing a median of 240 BPH patients during the preceding 12 months, and they had prescribed alpha-blockers for 70 and finasteride for 15. They had performed a median of 25 transurethral prostatectomies but few other operations for BPH. Almost all urologists routinely used digital rectal examinations and prostate specific antigen tests for BPH diagnosis. The next most common studies were American Urological Association symptom scores and uroflowmetry. Pressure-flow studies were rarely done. Respondents reported seeing a median of 35 new patients with prostate cancer during the last year, and performing a median of 90 prostate biopsies and 13 radical prostatectomies. Respondents had referred a median of 10 patients for external beam radiotherapy but few patients received brachytherapy or cryotherapy. Urologist staging practices varied considerably. CONCLUSIONS: These data provide a picture of current practice regarding the management of BPH and prostate cancer.

Data Collection↗
PubMed1997

Diagnosis and treatment of benign prostatic hyperplasia. Practice patterns of primary care physicians.

OBJECTIVE: To define primary care physicians' (PCPs) practices in managing patients with benign prostatic hyperplasia [BPH], and to compare these practices to portions of the Agency for Health Care Policy and Research BPH guideline and urologists' practices. DESIGN: Mail survey. PARTICIPANTS: Nationwide random sample of PCPs and urologists, selected from the American Medical Association Registry. METHODS: Initial mailing, postcard reminder, second mailing, telephone reminder, final mailing. MAIN RESULTS: Primary care physicians (n = 444, response = 51%) reported seeing a median of 35 patients with BPH over the preceding year, in contrast to 240 for urologists (n = 394, response = 68%). Regarding tests recommended by the guideline, two thirds of PCPs reported rarely or never using the American Urological Association (AUA) symptom index, nearly all reported routinely performing digital rectal examinations, and many (66%) reported routinely ordering tests to determine the serum creatinine level. Although considered "optional" by the guideline, more than 90% of PCPs reported routinely ordering a prostate-specific antigen test, while infrequently using other optional tests. Regarding "not recommended" studies, a substantial minority reported selectively or routinely ordering intravenous pyelography (34%) and renal ultrasound (33%), while two thirds reported rarely or never ordering these tests. Eighty-six percent of PCPs reported prescribing medications for BPH over the preceding year; alpha blockers to a median of 12 patients, and finasteride to a median of 2. Variation in urology referral thresholds was suggested in responses to two patient scenarios. CONCLUSIONS: Primary care physicians are actively managing patients with BPH. Some of their diagnostic evaluations vary from the recommendations of a national guideline and urologists' practices. Referral thresholds appear to vary considerably.

Adult↗
PubMed1997

The natural history of patients with benign prostatic hyperplasia as diagnosed by North American urologists.

PURPOSE: We defined outcomes for men with a clinical diagnosis of benign prostatic hyperplasia. MATERIALS AND METHODS: We followed for 4 years 500 candidates for elective prostatectomy treated nonoperatively in 5 North American urology practices. RESULTS: There were 371 survivors with complete data at 4 years. Of 60 men with mild, 245 with moderate and 66 with severe baseline symptoms 10, 24 and 39%, respectively, had undergone surgery; 27, 31 and 27%, respectively, were on pharmacological therapy, and 63, 45 and 33%, respectively, were off active treatment at 4 years. Mild or moderate symptoms were noted at 4 years in 83, 59 and 23% of the patients, respectively, while 17, 41 and 77%, respectively, had severe symptoms or had undergone surgery. CONCLUSIONS: Outcomes for men with a clinical diagnosis of benign prostatic hyperplasia depend on initial symptom severity. However, the course of symptoms also varies among patients even with the same initial symptom severity.

Cohort Studies↗
PubMed1996

Urinary mercapturic acid diastereoisomers in rats subchronically exposed to styrene and ethanol.

Styrene is stereoselectively oxidized by cytochrome P450 to its reactive metabolite, styrene oxide. The (R)- and (S)-enantiomers of styrene oxide can be conjugated with glutathione (GSH) to both (R)- and (S)-diastereoisomers of the specific mercapturic acids, N-acetyl-S-(1-phenyl-2-hydroxyethyl)-L-cysteine (M1) and N-acetyl-S-(2-phenyl-2-hydroxyethyl)-L-cysteine (M2). Several investigations have indicated different toxic potential of the (R)- and (S)-configurations of styrene oxide and its GSH- and N-acetyl-conjugates. In this study the mercapturic acid diastereoisomers were measured in the urine of rats exposed to styrene in combination with ethanol, a good inducer of styrene metabolism. Male Sprague-Dawley rats were given an isocaloric liquid diet containing ethanol (5% w/v) for 3 weeks. Starting from the 2nd week, the animals were also exposed to styrene vapours (300 ppm, 6 h/day, 5 days/week) in a dynamic exposure chamber. Both the (R)- and (S)-diastereoisomers of the M1 and M2 as well as the conventional biomarkers, mandelic acid (MA) and phenylglyoxylic acid (PGA) were measured in urinary samples. Approximately 30 and 25% reduction of the levels of brain non-protein sulfhydryls (NPS) was observed in the animals given styrene and ethanol, respectively, while the combined ethanol and styrene treatment resulted in a 60% decrease. Ethanol consumption also resulted in higher urinary levels of the M1-R, M1-S and M2 metabolites associated with increased M1-R/S ratio and higher urinary MA excretion compared to animals treated with styrene. These results suggest that the urinary mercapturic acid diastereoisomers may be used as a noninvasive tool to examine stereoselective patterns of styrene metabolism in vivo, as well as their alterations caused by ethanol. These compound-specific mercapturic acids may also be valuable indicators of styrene-induced disorders of GSH homeostasis in nonaccessible organs.

Acetylcysteine↗
PubMed1996

Outcomes of external-beam radiation therapy for prostate cancer: a study of Medicare beneficiaries in three surveillance, epidemiology, and end results areas.

PURPOSE: This study was designed to obtain representative estimates of the quality of life and probabilities of possible adverse effects among Medicare-age patients treated with external-beam radiation therapy for prostate cancer. METHODS: Patients treated for local or regional prostate cancer with high-energy external-beam radiation between 1989 and 1991 were sampled from a claims data base of the Surveillance, Epidemiology, and End Results (SEER) program from three regions. Patients were surveyed primarily by mail, with telephone follow-up evaluation of non-respondents. There were 621 respondents (83% response rate). The results were compared with data from a previously published national survey of Medicare-age men who had undergone radical prostatectomy. RESULTS: Although they were older at the time of treatment, radiation patients were less likely than surgical patients to wear pads for wetness (7% v 32%) and had a lower rate of impotence (23% v 56% for men < 70 years), while they were more likely to report problems with bowel dysfunction (10% v 4%). Both groups reported generally positive feelings about their treatments. Radiation and surgical patients reported similar rates of additional subsequent treatment (24% v 26% at 3 years after primary treatment). However, radiation patients were less likely to say they were cancer-free, and they reported more worry about cancer than did surgical patients. CONCLUSION: The health-related quality of life of radiation and surgical patients, on average, is similar, but the pattern of experience with adverse consequences of treatment differs by treatment.

Aged↗
PubMed1980

[Cinematographic and morphometric analysis of in vitro behavior of blastocysts of the mouse].

The behaviour of the mouse blastocyst in vitro was studied by time-lapse cinematography and analysed by morphometry. Three types of behaviour were observed: discontinuous expansion interrupted by rapid contractions and followed or not by hatching; practically continuous expansion followed by hatching. This demonstrates that the pulsatile activity of the blastocyst is not a necessary condition of hatching. Analysis of the rate and delay of hatching in vitro as compared to the conditions in utero is in favour of the existence of a uterine factor insuring partial lysis of the zona pellucida and helping the mechanical action of the blastocyst. Hatching by herniation through a reduced opening of the zona was occasionally observed. The process of in vitro implantation could be followed by cinematography.

Animals↗