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Biomedical subjects

S Liu

Publications and source records attributed to S Liu.

1,168 records · Page 65Linked to original sources
PubMedDate not supplied

Birth cohort effects underlying the increasing testicular cancer incidence in Canada.

PURPOSE: To examine the pattern of testicular cancer incidence by age, time period and birth cohort since 1969 in Canada. METHODS: In addition to analyses of the secular trends by age group and birth cohort separately, an age-period-cohort model and the submodels with standard Poisson assumptions were fitted to the data. RESULTS: The overall age-adjusted incidence of testicular cancer increased in Canada, from 2.8 per 100,000 males in 1969-71 to 4.2 in 1991-93. The younger age groups showed much higher absolute incidence rates in the recent period compared with those in the early period. Age-period-cohort modelling of data restricted to males aged 20-84 years suggested that the observed increase in testicular cancer could be largely attributed to a birth cohort effect. A steady increase in risk was observed among men born since 1945; those born between 1959 and 1968 were 2.0 (95% CI, 1.5-2.6) times as likely to develop testicular cancer as those born between 1904 and 1913. CONCLUSION: The risk of testicular cancer has increased over time and changing exposure to environmental factors early in life may be responsible for this.

Adolescent↗
PubMedDate not supplied

Regional patterns of infant mortality caused by lethal congenital anomalies.

PURPOSE: To assess the regional patterns of infant mortality due to lethal congenital anomalies, and the potential reasons for the regional patterns. METHOD: The study analyzed 2,507 infant deaths due to lethal congenital anomalies among 1,178,452 live births in 9 of the 12 Canadian provinces and territories from 1990 to 1995 recorded in Statistics Canada's live birth and death data bases. RESULTS: Compared with the province of Quebec, congenital anomaly-attributed infant mortality was higher in Newfoundland, Saskatchewan, and Alberta. These differences in infant mortality were substantial for cardiovascular system anomalies and especially anencephaly. For infant mortality due to chromosomal anomalies, however, there was little inter-provincial variation. CONCLUSIONS: Despite substantial recent reductions in lethal congenital anomaly-attributed infant mortality, there remain major regional variations in infant mortality caused by certain forms of congenital anomalies including anencephaly and cardiovascular system anomalies.

Canada↗
PubMedDate not supplied

Increased neonatal readmission rate associated with decreased length of hospital stay at birth in Canada.

PURPOSE: To assess the potential impact of early post birth discharge in Canada. METHODS: Neonatal readmission was examined, based on hospital discharge data from the Canadian Institute for Health Information, with a total of 2,144,205 infants from fiscal year 1989/90 to fiscal year 1996/97. RESULTS: Neonatal readmission rates increased from 27.3 per 1,000 in 1989/90 to 38.0 per 1,000 in 1996/97, while mean length of hospital stay at birth decreased from 4.2 days to 2.7 days during the same period. The increase in readmission rate was more evident for dehydration and jaundice. The provinces and territories with decreased length of hospital stay at birth usually had increased neonatal readmission rate and earlier age at readmission. Between 1994/95 and 1996/97, compared with Newfoundland, the risks for neonatal readmission for dehydration were 5.7 and 5.5, and for jaundice were 4.5 and 2.7, respectively, for Alberta and Ontario. CONCLUSION: Neonatal readmission rates for several conditions have increased substantially, associated with early post birth discharge policies adopted in Canada.

Canada↗
PubMedDate not supplied

Imageability and word recognition in the left and right visual fields: a signal detection analysis.

Identifying the information processing constraints that determine whether or not imagery moderates visual field asymmetries is essential for constructing a dynamic model of hemispheric interaction during language processing. In this investigation, we manipulated the global experimental context in which imageable and nonimageable words were presented by contrasting mixed and blocked word lists using a lateralized lexical decision task. Signal detection analyses were employed to assess whether global stimulus context and imageability differentially affect word discriminability (d prime) and response bias (log beta) across visual fields. Both discriminability and response bias varied with imageability and stimulus context, but to a comparable extent across visual fields. This suggests that both hemispheres are sensitive to the global context in which words are presented, and can adjust processing based not only on semantic characteristics of the words themselves, but also on the variability of items in the stimulus environment.

Cognition↗
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Time trends and sex patterns in Hodgkin's disease incidence in Canada, 1970-1995.

PURPOSE: To examine time trends and sex patterns in Hodgkin's disease incidence in Canada, from 1970 through 1995. METHOD: In addition to analyses of the secular trends and sex ratio in incidence rates, age-period-cohort models were fitted to estimate the effects on the trends. Age-specific male/female incidence rate ratios were examined for the disease and for its two major histologic subtypes. RESULTS: The overall age-adjusted incidence rate of Hodgkin's disease decreased significantly in males (3.5 per 100,000 in 1970-71 to 2.8 in 1994-95) but only slightly in females (2.4 per 100,000 to 2.3). There was a significant increase in the incidence among females aged 10-29 and among males aged 10-24, but a dramatic decrease among older ages. Age-period-cohort modelling showed that birth cohort and period effects were responsible for the observed trends in males and females, respectively. CONCLUSION: The risk factors responsible for Hodgkin's disease are different in females and males. Reproductive factors are likely to be associated with the occurrence of the disease in young women.

Adolescent↗
PubMedDate not supplied

The effects of gossypol on the invasiveness of MAT-LyLu cells and MAT-LyLu cells from the metastasized lungs of MAT-LyLu-bearing Copenhagen rats.

Recently, we isolated a novel subline of the MAT-LyLu cell line from the metastasized lungs of MAT-LyLu-bearing Copenhagen rats (MLL cells). In this study, we compared the MLL cells to the parental MAT-LyLu cells with respect to invasive ability, mRNA expression level for the nm23 metastasis suppressor gene, and response to gossypol (GP), a natural compound with documented antiproliferative and antimetastatic activity, in an in vitro invasion assay. ML cells were isolated from mechanically dissociated metastasized lungs from MAT-LuLu-bearing Copenhagen rats. Comparisons of the invasive ability and steady-state levels of nm23 mRNA between MLL and MAT-LuLu cells were determined by in vitro invasion assay and RT-PCR, respectively. The results show that MLL cells display a higher penetration percentage than MAT-LyLu cells in the in vitro invasion assay. Furthermore, RT-PCR revealed that MLL cells possess lower steady state levels of nm23 mRNA than MAT-LyLu cells, suggesting a molecular basis for the observed differences in in vitro invasive ability. Finally, both MLL and MAT-LyLu cells were susceptible to gossypol, which induced dose-dependent inhibition of invasive activity. These results report the isolation of a novel, more highly invasive subline of the MAT-LyLu cell line that is as susceptible to the inhibitory effects of gossypol as the parental MAT-LyLu cells. The MLL cells, in combination with the parental MAT-LyLu cells, can be valuable tools for investigating the biology and behavior of metastatic cells and their response to chemotherapeutic/preventive agents.

Animals↗
PubMedDate not supplied

Geographic pathology on the precursors of stomach cancer.

The classification of dysplasias of the gastric mucosa used in our institute includes adenomatous dysplasia, regenerative dysplasia, and cryptal dysplasia. We compared the incidence of gastric dysplasia in three regions of China which have quite different geographical environments: the loess plateau of Wuwei area in the Gansu Province, the island of the Yangtze River in the Jiangsu Province of southern China, and the coastal area of the Liaoning Province in northern China. The mortality rate of stomach cancer in these areas is more than 50 per 100,000. We found a total of 323 cases of gastric dysplasia in these three areas. Regenerative dysplasia is the most common precancerous lesion of the stomach and was found in 40% of the cases from the three high-risk areas of gastric cancer. The background lesions consist of gastric erosions, severe gastritis, gastric ulcers, and intestinal metaplasia, which indicate that some factors causing damage to gastric mucosa are very important in the histogenesis of stomach cancer. The gastric dysplasia sites involved are different in the three geographical regions studied. On the island of the Yangtze River, cardiac dysplasia and intestinal metaplasia are common (75%), and cancer of the cardia is also common. In the other two geographical areas, antral dysplasia predominates (85 to 91%). The finding of different sites of gastric dysplasia in different geographical environments may be very important in our search for etiological factors of gastric cancer and may allow for beneficial intervention in the prevention of this disease.

Adult↗
PubMedDate not supplied

[Molecular cloning and characterization of a novel WRKY gene from Brassica chinensis].

A new WRKY gene was cloned from Brassica chinensis by rapid amplification of cDNA ends (RACE). The full-length cDNA of BcWRKY was 1175 bp long and contained a 924 bp open reading frame (ORF) encoding a putative W-box-binding protein of 308 amino acids. The predicted BcWRKY protein was found to have a potential bipartite nuclear localization sequence (NLS-BP) in its N-terminal region followed by a WRKY DNA-binding domain. Bioinformatic analysis revealed that BcWRKY resembled other WRKY domain-containing proteins from Arabidopsis (AtWRKY18), tobacco (WIZZ), parsley (PcWRKY4) and wild oat (ABF2). Expression of the BcWRKY gene could be induced by salicylic acid (SA), and influenced by Pseudomonas syringae pv. tomato strain DC3000 infection and wounding treatment. Our study implies that BcWRKY might have similar functions possessed by other WRKY genes such as inducing the expression of some defense-related genes and increasing plant's disease resistance ability.

Amino Acid Sequence↗
PubMedDate not supplied

Effects of epidural bupivacaine after thoracotomy.

BACKGROUND AND OBJECTIVES: Combinations of bupivacaine and fentanyl are popular for postoperative epidural analgesia. However, there are little data from which to select a rational dose of bupivacaine. The study examined the effects of increasing amounts of epidural bupivacaine on postoperative analgesia, epidural fentanyl consumption, and side effects after thoracotomy. METHODS: Twenty-four patients were randomized in a double-blind manner to receive intra- and postoperative epidural infusions of either saline, 0.01% bupivacaine, 0.05% bupivacaine, or 0.1% bupivacaine at 10 mL/h. All patients received a standardized combined epidural (120 mg lidocaine and 1.5 micrograms/kg of fentanyl) and general anesthesia. Further postoperative analgesia was provided with fentanyl patient-controlled epidural analgesia (PCEA) only. RESULTS: There were no differences between groups in visual analog scale (VAS) pain scores at rest or cough, but 10 and 5 mg/h of bupivacaine provided better analgesia during physiotherapy (P < .05). The use of 10 and 5 mg/h of bupivacaine led to significant opioid sparing (50% decrease) when compared to saline and 1 mg/h bupivacaine (P < .03). There was a trend toward a greater incidence of orthostasis with the use of bupivacaine at 10 mg/h (P = .09). Incidences of opioid side effects were not different between groups. CONCLUSIONS: The results demonstrate improved analgesia with physiotherapy and significant opioid sparing when 10 and 5 mg/h doses of bupivacaine are used. However, the incidence of orthostasis may be increased with the use of 10 mg/h. Thus, 5 mg/h of epidural bupivacaine (.05% at 10 mL/h) improved analgesia, decreased opioid requirements, and did not have detectable hemodynamic effects.

Aged↗
PubMedDate not supplied

Prolonged PR interval is a risk factor for bradycardia during spinal anesthesia.

BACKGROUND AND OBJECTIVES: Bradycardia occurs during 9%-13% of spinal anesthetics and may lead to cardiac arrest. Several risk factors for the development of bradycardia have been identified, but the risk conferred by presence of abnormalities detected on preoperative electrocardiogram (ECG) has not been examined. The authors undertook the study to correlate abnormal ECG findings with the incidence of bradycardia. METHODS: The data-base was previously collected from 952 patients undergoing spinal anesthesia. Patient records were reviewed and 537 had ECGs performed within 6 months of surgery. Intraoperative bradycardia was defined as a heart rate < 50 bpm (plus > 10% decrease from baseline). Abnormalities recorded from the ECG were prolonged PR interval (PR > 0.2 sec), atrial-ventricular conduction abnormalities, evidence of chamber hypertrophy, ischemia, and infarction. The findings were compared with incidence of bradycardia using contingency tables. Significant correlations were then evaluated with logistic regression. Significance was defined as P < .05. RESULTS: The incidence of bradycardia in this population was 12%. Patients with a prolonged PR interval had an increased incidence of bradycardia (25%, P = .01). Other ECG abnormalities did not correlate with increased incidence of bradycardia. Duration of PR interval did correlate significantly (P = .001) but poorly (r2 = 0.014) with baseline heart rate. However, logistic regression demonstrated that prolonged PR interval was a significant and independent predictor for bradycardia (odds ratio = 3.2, P = .01). CONCLUSIONS: Risk factors previously identified for the development of bradycardia during spinal anesthesia include: baseline heart rate < 60 bpm, ASA physical status 1 versus 3 or 4, use of beta-blocking drugs, sensory block height > or = T5, and age < 50. The results demonstrate that prolonged PR interval on the preoperative ECG is another significant and independent predictor for bradycardia.

Adult↗
PubMedDate not supplied

Epinephrine prolongs duration of subcutaneous infiltration of local anesthesia in a dose-related manner. Correlation with magnitude of vasoconstriction.

BACKGROUND AND OBJECTIVES: Epinephrine is frequently combined with local anesthesia to prolong analgesia. Determination of the minimal concentration and the dose of epinephrine that produces prolongation of analgesia is important in the face of epinephrine's potential for systemic and local toxicity. The authors undertook this study to determine a dose-response curve of epinephrine on duration of analgesia of both 1% lidocaine and 0.25% bupivacaine after local infiltration. In order to determine whether epinephrine-induced vasoconstriction affected duration of analgesia, the authors correlated duration of analgesia with magnitude of local vasoconstriction as measured with laser Doppler flowmetry. METHODS: Six volunteers were studied in a randomized double-blind manner. Ten skin wheals of 0.2 mL solution were subcutaneously injected into both forearms of each volunteer. The solutions consisted of 1% lidocaine with epinephrine concentrations of 0, 1:50,000, 1:200,000, 1:800,000, and 1:3,200,000, and 0.25% bupivacaine with the same epinephrine concentrations. Duration of loss of sensation to pinprick at each wheal was recorded. Skin wheals with 0.2 mL of these same solutions were also subcutaneously injected into the abdomen of the same 6 volunteers, and laser Doppler flowmetry readings of skin blood flow were measured for 6 hours after injection. RESULTS: Epinephrine prolonged duration of analgesia for both lidocaine and bupivacaine in a dose-related manner (P < .001). All concentrations of epinephrine attenuated the vasodilation observed in the first 15 minutes after injection with plain local anesthesia (P = .03), and blood flow returned to baseline by 30 minutes after injection of either plain or epinephrine-containing solutions. Duration of analgesia correlated with magnitude of vasoconstriction only at the 15-minute measurement (r = .53 and .57, P = .003 and 0.001 for lidocaine and bupivacaine, respectively). CONCLUSIONS: Epinephrine prolongs duration of analgesia after local infiltration in a dose-related manner. Addition of epinephrine in concentrations of 1:50,000 or 1:200,000 increases duration of analgesia after local infiltration by approximately 200%. Addition of doses as dilute as 1:3,200,000 still increases duration of analgesia by approximately 100%. Duration of analgesia appears to correlate with magnitude of epinephrine-induced vasoconstriction using laser Doppler flowmetry. Based on study data, the use of epinephrine in concentrations from 1:200,000 to 1:3,200,000 is recommended for prolongation of analgesia after local infiltration.

Adrenergic Agonists↗
PubMedDate not supplied

Comparison of thrombelastography with common coagulation tests in preeclamptic and healthy parturients.

BACKGROUND AND OBJECTIVES: Epidural analgesia/anesthesia is often beneficial in the management and treatment of preeclampsia. However, some preeclamptic patients have a coagulopathy that is a contraindication to regional anesthesia. A routine coagulation battery (RCB) consisting of prothrombin time, partial thromboplastin time, platelet count, and bleeding time, is commonly performed to assess coagulation status. Thrombelastography (TEG) is a measure of clotting that allows evaluation of overall coagulation activity. The goal of this study was to examine whether TEG can predict normal and abnormal coagulation as diagnosed by RCB in healthy and preeclamptic parturients. METHODS: Forty-seven parturients participated in this prospective study, performed early in the first stage of labor. Twenty healthy parturients (group I), 19 mild (group II), and 8 severe preeclamptic/eclamptic parturients (group III) had RCB and TEG performed. RESULTS: Five patients (1, group I; 3, group II; 1, group III) had a normal RCB, but a mildly abnormal TEG (prolonged K, small alpha) (specificity = 0.88). Five of 27 preeclamptic parturients (1, group II; 4, group III) had abnormal RCBs. Three of these 5 patients had thrombocytopenia with normal bleeding times and TEGs. Two patients had thrombocytopenia and prolonged bleeding times and abnormal TEGs (sensitivity = 0.40). CONCLUSION: Thrombelastography is not an effective means of predicting abnormal coagulation, as diagnosed by RCB, in preeclamptic parturients, using currently defined normal TEG values for nonpregnant patients. However, an abnormal TEG maximum amplitude value always correlated with a prolonged bleeding time. Therefore, TEG may be useful in assessing platelet function in the presence of thrombocytopenia. Further studies are warranted.

Adult↗
PubMedDate not supplied

Kidney cancer in Canada: the rapidly increasing incidence of adenocarcinoma in adults and seniors.

PURPOSE: To examine kidney cancer incidence and mortality patterns since 1969 in Canada. METHOD: Linear regression of the log rates was used to estimate secular trends by age group and sex, and age-period-cohort models were fitted to examine changes in kidney cancer and renal adenocarcinoma incidence rates. RESULTS: A substantial increase in incidence rates was observed among those 35 years and older, with average increases of 2.5% or more annually for both sexes. Age-period-cohort modelling suggested that much of this increase resulted from a period effect. Changes in mortality were much more modest, especially among those aged 0-34, for whom mortality rates actually declined by an average of 4.2% and 5.4% annually for males and females respectively. CONCLUSIONS: Kidney cancer incidence rates have increased significantly, especially renal adenocarcinoma among adults and seniors. Diagnostic improvements and increasing levels of obesity in the Canadian population may have contributed to these trends.

Adenocarcinoma↗
PubMedDate not supplied

Transforming growth factor-beta 1 regulates the expression of Pax-2, a developmental control gene, in renal tubule cells.

BACKGROUND/AIMS: The pattern-forming event of kidney tubulogenesis is initiated by the inductive transition of mesenchymal cells to epithelial phenotype; a transition that is critically dependent on the regulated expression of the developmental control gene, Pax-2. Because of a defined role in in vitro renal tubulogenesis, the effects of epidermal growth factor (EGF), transforming growth factor (TGF)-beta 1 and retinoic acid on Pax-2 gene expression in proximal tubule cells (PTC) were evaluated. METHODS: Rabbit PTC were isolated and grown in tissue culture. Under confluent quiescent conditions, the effect of various factors on Pax-2 gene expression was assessed by Northern blot analysis. To assess whether the effect of TGF-beta 1 to alter Pax-2 gene expression was due to transcriptional or posttranscriptional events, nuclear run-on assays were also undertaken. RESULTS: Under control, confluent growth conditions, PTC expressed high levels of Pax-2. A 24-hour exposure to EGF (10 nM), a potent mitogen of PTC, increased this level of expression. In contrast, Pax-2 gene expression was suppressed by treating PTC with retinoic acid (10 mM), a well-described differentiating factor, and with TGF-beta 1 (10 ng/ml), a recognized antiproliferative agent for these cells, which suggests that Pax-2 has a role in renal cell proliferation. The mechanism of the effect of TGF-beta 1 on Pax-2 mRNA levels was further detailed. TGF-beta 1 did not affect Pax-2 transcription rates, as assessed by nuclear run-on assays; however, in a dose-dependent manner, it diminished the stability of Pax-2 mRNA. At a concentration of 10 ng/ml, TGF-beta 1 reduced Pax-2 mRNA stability from a control half-life of 120 min to a half-life of less than 60 min. CONCLUSION: This study demonstrates that various soluble inductive factors affect Pax-2 gene expression in renal tubule cells. Also, TGF-beta 1 downregulates Pax-2 gene expression through a posttranscriptional process, an acknowledged mechanism for modulating important growth regulatory gene products.

Animals↗
PubMedDate not supplied

Trends and variations in neonatal length of in-hospital stay in Canada.

PURPOSE: To analyze spatio-temporal variations of neonatal length of in-hospital stay in Canada. METHOD: The length of in-hospital stay of 1,469,761 newborns in Canadian hospitals from April 1, 1984 to March 31, 1995 recorded by the Canadian Institute for Health Information was analyzed. RESULTS: Neonatal length of in-hospital stay decreased from an average of 5.0 days in 1984 to 2.9 days in 1994. In 1994, the average neonatal length of in-hospital stay in Alberta was 2.5 days, which was 0.2 to 1.5 days shorter than other provinces. The spatio-temporal variations in neonatal length of in-hospital stay could not be explained by corresponding variations in birthweight and other neonatal disorders. CONCLUSIONS: Neonatal length of in-hospital stay has been substantially reduced in Canada in recent years but there remain important interprovincial variations. These variations are unlikely to be the results of changes or differences in patient-specific factors; policy played an important role.

Canada↗