IMpower131: Primary PFS and safety analysis of a randomized phase III study of atezolizumab + carboplatin + paclitaxel or nab-paclitaxel vs carboplatin + nab-paclitaxel as 1L therapy in advanced squamous NSCLC

LBA9000

Background: Atezolizumab (atezo; anti–PD-L1) demonstrated OS benefit vs docetaxel in 2L+ NSCLC regardless of PD-L1 status or tumor histology. Because cytotoxic agents can exhibit positive immunomodulatory effects, combining atezo with chemotherapy may further improve outcomes. IMpower131 (NCT02367794) was designed to evaluate atezo + carboplatin (carbo) + paclitaxel (pac) or nab-paclitaxel (nab-pac) in 1L stage IV squamous NSCLC. Methods: Patients (pts) were randomized 1:1:1 to Arm A (atezo 1200 mg q3w + carbo AUC 6 q3w + pac 200 mg/m2 q3w), Arm B (atezo + carbo + nab-pac 100 mg/m2 weekly) or Arm C (carbo + nab-pac). Pts received chemotherapy for 4 or 6 cycles and atezo until loss of clinical benefit. We present the primary analysis of investigator (INV)-assessed PFS per RECIST v1.1 in the ITT population for Arm B vs Arm C. Data cutoff: 22 January 2018. Results: 338 pts (Arm A), 343 pts (Arm B) and 340 pts (Arm C) were enrolled. Minimum follow-up was 9.8 mo. INV-assessed median PFS was 6.3 mo in Arm B vs 5.6 mo in Arm C (HR, 0.715; 95% CI: 0.603, 0.848; P = 0.0001). PFS benefit was enriched in all PD-L1–positive IHC subgroups and was most pronounced in TC3 or IC3. AEs related to any treatment (TRAEs) were 91.3% (Arm A), 94.6% (Arm B) and 90.7% (Arm C); Grade 3-4 TRAEs were 42.8% (Arm A), 68.0% (Arm B) and 56.9% (Arm C); serious TRAEs were 22.3% (Arm A), 20.4% (Arm B) and 10.5% (Arm C). Preliminary OS data will be presented. Conclusions: IMpower131 met its co-primary endpoint of INV-assessed PFS in the ITT population in Arm B vs Arm C. The safety profile of atezo + carbo + nab-pac or pac was consistent with the known risks of the individual treatment components; no new safety signals were identified. Clinical trial information: NCT02367794. [Table: see text]

Phase Ia study of the indoleamine 2,3-dioxygenase 1 (IDO1) inhibitor navoximod (GDC-0919) in patients with recurrent advanced solid tumors

BACKGROUND

Indoleamine-2,3-dioxygenase 1 (IDO1) catalyzes the oxidation of tryptophan into kynurenine and is partially responsible for acquired immune tolerance associated with cancer. The IDO1 small molecule inhibitor navoximod (GDC-0919, NLG-919) is active as a combination therapy in multiple tumor models.

METHODS

This open-label Phase Ia study assessed safety, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary anti-tumor activity of navoximod in patients with recurrent/advanced solid tumors, administered as 50-800 mg BID on a 21/28 day and at 600 mg on a 28/28 day schedule. Plasma kynurenine and tryptophan were longitudinally evaluated and tumor assessments were performed.

RESULTS

Patients (n = 22) received a median of 3 cycles of navoximod. No maximum tolerated dose was reached. One dose-limiting toxicity of Grade 4 lower gastrointestinal hemorrhage was reported. Adverse events (AEs) regardless of causality in ≥20% of patients included fatigue (59%), cough, decreased appetite, and pruritus (41% each), nausea (36%), and vomiting (27%). Grade ≥ 3 AEs occurred in 14/22 patients (64%), and were related to navoximod in two patients (9%). Navoximod was rapidly absorbed (Tmax ~ 1 h) and exhibited dose-proportional increases in exposure, with a half-life (t1/2 ~ 11 h) supportive of BID dosing. Navoximod transiently decreased plasma kynurenine from baseline levels with kinetics consistent with its half-life. Of efficacy-evaluable patients, 8 (36%) had stable disease and 10 (46%) had progressive disease.

CONCLUSIONS

Navoximod was well-tolerated at doses up to 800 mg BID decreasing plasma kynurenine levels consistent with its half-life. Stable disease responses were observed.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02048709 .

Estimation of treatment effects in weighted log-rank tests

Non-proportional hazards have been observed in clinical trials. The log-rank test loses power and the standard Cox model generally produces biased estimates under such conditions. Weighted log-rank tests have been utilized to increase the test power; however, it is not intuitive how to interpret the test result in terms of the clinical effect. We propose a Cox-model based time-varying treatment effect estimate to complement the weighted log-rank test.

The score test from the proposed model is equivalent to the weighted log-rank test, and a time-profile of the treatment effect can be obtained by fitting a time-varying covariate Cox model. Simulation results show that the proposed model preserves type-I error and achieve higher power than log-rank tests under non-proportional hazards scenarios. Whereas the standard Cox model produces biased effect estimates, the proposed model produces unbiased estimates if the weight function is correctly specified. It also achieves a better model fit and an enhanced flexibility to accommodate non-proportional hazards compared to the standard Cox model.

The proposed approach makes the assumptions of the weighted log-rank test explicit and the validity of assumptions can be assessed based on prior knowledge or model goodness-of-fit. It also helps to translate the weighted log-rank test results into quantitative estimates of the treatment effect with intuitive interpretation. The proposed method can be routinely conducted to complement weighted log-rank tests, especially in the setting where non-proportional hazards are expected.

Phase I Dose-Escalation Study of Taselisib, an Oral PI3K Inhibitor, in Patients with Advanced Solid Tumors

Taselisib is a potent and selective tumor growth inhibitor through PI3K pathway suppression. Thirty-four patients with locally advanced or metastatic solid tumors were treated (phase I study, modified 3+3 dose escalation; 5 cohorts; 3-16 mg taselisib once-daily capsule). Taselisib pharmacokinetics were dose-proportional; mean half-life was 40 hours. Frequent dose-dependent, treatment-related adverse events included diarrhea, hyperglycemia, decreased appetite, nausea, rash, stomatitis, and vomiting. At 12 and 16 mg dose levels, dose-limiting toxicities (DLT) were observed, with an accumulation of higher-grade adverse events after the cycle 1 DLT assessment window. Pharmacodynamic findings showed pathway inhibition at ≥3 mg in patient tumor samples, consistent with preclinical PIK3CA-mutant tumor xenograft models. Confirmed response rate was 36% for PIK3CA-mutant tumor patients with measurable disease [5/14: 4 breast cancer (3 patients at 12 mg); 1 non-small cell lung cancer], where responses started at 3 mg, and 0% in patients with tumors without known PIK3CA hotspot mutations (0/15).Significance: Preliminary data consistent with preclinical data indicate increased antitumor activity of taselisib in patients with PIK3CA-mutant tumors (in comparison with patients with tumors without known activating PIK3CA hotspot mutations) starting at the lowest dose tested of 3 mg, thereby supporting higher potency for taselisib against PIK3CA-mutant tumors. Cancer Discov; 7(7); 704-15. ©2017 AACR.See related commentary by Rodon and Tabernero, p. 666This article is highlighted in the In This Issue feature, p. 653.

Abstract OT1-1-01: LORELEI: A Phase II randomized, double-blind study of neoadjuvant letrozole plus taselisib (GDC-0032) versus letrozole plus placebo in postmenopausal women with ER-positive/HER2-negative, early stage breast cancer

Background: Taselisib (GDC-0032) is an orally bioavailable, potent, and selective inhibitor of Class I PI3-kinase (PI3K) alpha, gamma, and delta isoforms, with 30-fold less inhibition of the PI3K beta isoform relative to the PI3K alpha isoform. Preclinical data show that taselisib has enhanced activity against PIK3CA mutant cancer cell lines. Clinical data have also demonstrated confirmed partial responses in patients with PIK3CA mutant breast cancer treated with single-agent taselisib. Preclinical and clinical data also show enhanced antitumor activity when taselisib is combined with either letrozole or fulvestrant.

Study design: LORELEI is a phase II, two-arm, randomized, double-blind, multicenter, neoadjuvant study of letrozole and taselisib versus letrozole and placebo in postmenopausal women with newly diagnosed ER+/HER2-, untreated, stage I-III operable breast cancer. Other relevant eligibility criteria include tumor size ≥ 2 cm, unilateral disease, ECOG PS ≤1, and available and evaluable tumor tissue for central review of PIK3CA mutation analysis. Patients will be randomized (1:1) to receive continuous daily letrozole (2.5 mg) with either placebo or taselisib (4mg on a 5 days on/ 2 days off schedule) for 16 weeks. Study treatment is followed by surgery. Adjuvant treatment will be given as per physician’s discretion. Stratification at randomization is based on tumor size and nodal status.

Endpoints: The co-primary endpoints are overall objective response rate (ORR) by centrally assessed breast magnetic resonance imaging (MRI) via modified RECIST criteria and pathologic complete response (pCR) rate in breast and axilla at time of surgery in all enrolled patients and PIK3CA mutant (MT) patients. Secondary endpoints include ORR by centrally assessed MRI and pCR rate in PIK3CA wild-type (WT) patients. Other secondary endpoints performed in all enrolled patients and separately as per PIK3CA mutation status include: assessment of ORR using breast ultrasound, clinical breast exam (i.e. palpation) and mammography; changes in Ki67 levels from baseline to week 3, baseline to surgery and week 3 to surgery; centrally assessed preoperative endocrine prognostic index (PEPI) score; changes in enhancing tumor volume from baseline to surgery as measured by breast MRI via central assessment. Exploratory analyses include expression of biomarkers predictive of response to letrozole plus taselisib from tumor tissue or blood.

Statistical methods:

The sample size was calculated to detect an absolute percentage increase of 24% in ORR via MRI (40% in the letrozole-placebo arm vs. 64% in the letrozole-taselisib arm in the PIK3CA MT cohort) with 80% power at 16% two-sided significance level. The sample size will also detect an absolute percentage increase of 18% in pCR rate (1% in the letrozole-placebo arm vs 19% in the letrozole-taselisib arm in the PIK3CA MT cohort) with 80% power at 4% two-sided significance level.

Target accrual: Approximately 330 pts at 110 global sites across Europe, North and South America, and Asia-Pacific.

Reference Study ID Numbers: GO28888/BIG-3-13/SOLTI 1205/ABCSG 38.

Citation Format: Cristina Saura, Evandro de Azambuja, Peter Dubsky, Mafalda Oliveira, Kamal S Saini, Christian Fes, Ray S Lin, Timothy R Wilson, Jill Fredickson, Hema Parmar, Jerry Y Hsu, Martine Piccard, Michael Gnant, Jose Baselga. LORELEI: A Phase II randomized, double-blind study of neoadjuvant letrozole plus taselisib (GDC-0032) versus letrozole plus placebo in postmenopausal women with ER-positive/HER2-negative, early stage breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr OT1-1-01.

Abstract 915: Expanded biomarker results from a phase I dose escalation study of GDC-0032, a beta isoform-sparing PI3K inhibitor

The phosphoinositol-3-kinase (PI3K) signaling pathway is one of the most frequently activated pathways in oncogenesis, and controls critical cellular processes such as proliferation, transcription and survival. GDC 0032 is an orally bioavailable, potent, and selective inhibitor of Class I PI3K alpha, delta, and gamma isoforms, with 30 fold less inhibition of the PI3K beta isoform relative to the PI3K alpha isoform. The gene that encodes the p110 alpha isoform of PI3K, PIK3CA, is frequently mutated in breast, colorectal and endometrial cancers. Preclinical data indicate that GDC-0032 has increased activity against PIK3CA mutant cancer cell lines.

As presented by Juric et al., 34 patients were enrolled in this study and dose escalation has been completed (Juric D. et al. AACR 2013, Abstract LB-64). Metabolic partial responses via FDG-PET were observed in 6 out of 13 patients assessed, and clinical partial responses (PRs) were observed in 6 patients, with 5 of these patients having PIK3CA mutant cancers. Tumor tissue was obtained from 30 out of 34 patients enrolled onto the study. The most frequently recruited cancer type was breast cancer (41%) followed by colorectal (15%) and lung cancer (15%). Fourteen patients enrolled onto the study had PIK3CA mutant tumors (41%) as determined using a TaqMan-based PCR assay. Three patients had total loss of PTEN expression, as assessed by immunohistochemical staining, and a further 3 patients had reduced PTEN expression based on a H-score assessment. Out of the 6 patients that had reduced PTEN expression, 2 patients had coexisting mutations with PIK3CA. Where known, 4 out of 5 patients that had a PR showed intact PTEN expression, with the fifth patient having reduced PTEN expression. Samples were further analyzed using an in-house developed PCR-based multiplexed assay that detects activating mutations within an additional ten oncogenes. PIK3CA mutations were largely mutually exclusive with mutations in the Ras pathway, however 3 out of the 14 PIK3CA mutant patients had a coexisting mutation within KRas. A further 2 patients had KRas mutations, 1 patient had a NRas mutation and 2 patients had EGFR mutations. Preliminary analysis suggests lack of benefit in patients with KRas mutations treated with GDC-0032 single agent. Optional on-study biopsies were collected from 2 patients and demonstrated pharmacodynamic inhibition of the PI3K pathway as assessed by reverse phase protein array for approximately 45 endpoints, including 1 patient at the lowest dose. In conclusion, our preliminary data indicates that GDC-0032 demonstrates single agent activity in patients with PIK3CA mutations tumors with unaltered PTEN or MAP-kinase pathways.

Citation Format: Timothy R. Wilson, Heidi Savage, Carol O'Brien, Sandra Sanabria, Ray S. Lin, Marie-Claire Wagle, Yibing Yan, Mark R. Lackner, Hema Parmar, Jerry Y. Hsu, Dejan Juric, Ian E. Krop, Ramesh K. Ramanathan, Daniel D. Von Hoff, Jose Baselga. Expanded biomarker results from a phase I dose escalation study of GDC-0032, a beta isoform-sparing PI3K inhibitor. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 915. doi:10.1158/1538-7445.AM2014-915

Abstract PD1-3: Ph1b study of the PI3K inhibitor GDC-0032 in combination with fulvestrant in patients with hormone receptor-positive advanced breast cancer

Background: GDC-0032 is a next-generation PI3K inhibitor with increased anti-tumor activity against PIK3CA mutant cancers. GDC-0032 is an orally bioavailable, potent, and selective inhibitor of Class I PI3K alpha, delta, and gamma isoforms, with 30-fold less inhibition of the PI3K beta isoform relative to the PI3K alpha isoform. Preclinical data show that GDC-0032 has enhanced activity against PI3K alpha isoform (PIK3CA) mutant breast cancer cell lines. Preclinical data also show enhanced antitumor activity when GDC-0032 is combined with fulvestrant.

Material and Methods: A Phase 1b dose escalation study was conducted with evaluation of GDC-0032 doses ranging from 6-9 mg QD in combination with fulvestrant 500mg q4wk (with loading dose of 500mg at day 1, 14 and 28) in a modified 3+3 design. A dose expansion cohort was conducted at the recommended Phase 2 dose of 6 mg QD. Safety and tolerability of GDC-0032 was assessed, as well as pharmacokinetics (PK), pharmacodynamic (PD) assessment of PI3K pathway inhibition by paired tumor biopsies and by FDG-PET, and anti-tumor activity by RECIST.

Results: As of 1 Mar 2013, 17 patients were enrolled onto this study with the completion of dose escalation. No dose limiting toxicities (DLTs) were observed at either the 6 mg or 9 mg dose levels. Adverse events (AEs) assessed by the investigator as related to GDC-0032 in ≥10% of patients, were diarrhea, hyperglycemia, stomatitis, fatigue, asthenia, decreased appetite, nausea, mucosal inflammation and rash. No observed apparent PK interactions were observed between GDC-0032 and fulvestrant. The median number of prior systemic therapies was 6. Metabolic partial responses via FDG-PET (≥ 20% decrease in mSUVmax) were observed in 8 out of 11 patients assessed (73%). Confirmed partial responses by RECIST have been observed at both the 6mg and 9mg GDC-0032 dose levels. These include patients who have had prior treatment with fulvestrant. As of 29 May 2013, enrollment onto the dose escalation and expansion cohort has been completed (n = 27). Updated data on safety, pharmacodynamics, efficacy, and biomarker correlates will be presented.

Conclusions: The combination of GDC-0032 and fulvestrant is a well-tolerated regimen with promising preliminary efficacy. GDC-0032 is being further investigated in combination with fulvestrant for patients with hormone receptor-positive advanced breast cancer.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD1-3.

Electromagnetic scanning to estimate carcass lean content of Taiwan native broilers

To estimate lean content of Taiwan native broiler carcasses accurately, objectively and rapidly, electrical conductivity measurements of broiler carcasses and other relative factors (carcass weight, length and temperature) were used in multiple linear regression analysis for lean prediction. Forty native broiler carcasses, with average market weight 2477.5±465.5 g, were scanned through a 10 MHz electromagnetic field created by an electromagnetic scanner (SA-3203) to measure the total body electrical conductivity (TOBEC) index. After scanning, each broiler carcass was separated into wing, breast, leg and back. Each primal cut was dissected into lean, fat and bone. The weight, length, temperature and TOBEC index of broiler carcass were significantly correlated with lean weight of broiler carcass (P<0.001). Regression analysis for lean estimation with carcass weight, length, temperature and TOBEC index showed higher coefficient of determination (R(2)=0.968) and lower coefficient of variation (CV=4.178) with an equation using beheaded carcass weight, temperature and TOBEC index as variables.

Use of wavefront encoding in optical interconnects and fiber switches for cross talk mitigation

A technique of cross talk mitigation developed for liquid crystal on silicon spatial light modulator based optical interconnects and fiber switches is demonstrated. By purposefully introducing an appropriate aberration into the system, it is possible to reduce the worst-case cross talk by over 10 dB compared to conventional Fourier-transform-based designs. Tests at a wavelength of 674 nm validate this approach, and show that there is no noticeable reduction in diffraction efficiency. A 27% spot increase in beam diameter is observed, which is predicted to reduce at longer datacom and telecom wavelengths.

Comparing the benefits of screening for breast cancer and lung cancer using a novel natural history model

To estimate the impact of early detection of cancer, knowledge of how quickly primary tumors grow and at what size they shed lethal metastases is critical. We developed a natural history model of cancer to estimate the probability of disease-specific cure as a function of tumor size, the tumor volume doubling time (TVDT), and disease-specific mortality reduction achievable by screening. The model was applied to non-small-cell lung carcinoma (NSCLC) and invasive ductal carcinoma (IDC), separately. Model parameter estimates were based on Surveillance Epidemiology and End Results (SEER) cancer registry datasets and validated on screening trials. Compared to IDC, NSCLC is estimated to have a lower probability of disease-specific cure at the same detected tumor size, shed lethal metastases at smaller sizes (median: 19 mm for IDC versus 8 mm for NSCLC), have a TVDT that is almost half as long (median: 252 days for IDC versus 134 days for NSCLC). Consequently, NSCLC is associated with a lower mortality reduction from screening at the same screen detection threshold and screening interval. In summary, using a similar natural history model of cancer, we quantify the disease-specific curability attributable to screening for breast cancer, and separately lung cancer, in terms of the TVDT and onset of lethal metastases.

Addressing Taiwan's high incidence of cervical cancer: factors associated with the Nation's low compliance with Papanicolaou screening in Taiwan

BACKGROUND

Despite cervical cancer being the leading female cancer, women in Taiwan have received fewer screening examinations for this disease than populations in Western countries.

METHODS

Randomly selected telephone questionnaire interviews with women aged 20 years and over were conducted to investigate the factors associated with the subject's cancer screening practices.

RESULTS

Among 1021 respondents, 51.6% self-reported no Papanicolaou (Pap) examination received within their lifetime. The multivariate logistic regression analysis revealed that, in addition to marital status, cancer knowledge was the most significant factor associated with screening practice compliance. Compared with women with correct answers for 22-28 cancer knowledge questions, the odds ratios (OR) for non-compliance were 1.4 (95% confidence interval (CI)=1.0-2.0) for women with 17-21 correct answers and 2.3 (95% CI=1.6-3.4) for women with less than 17 correct answers. Women aged 40-49 years had the best cancer knowledge scores. Unmarried women were at an elevated risk for no Pap examination (OR=7.6, 95% CI=5.2-11.3).

CONCLUSIONS

Women in Taiwan should be targeted for intervention to promote cancer knowledge and screening compliance.

Prediction of HIV mutation changes based on treatment history

Few studies have investigated sequential HIV-1 mutation changes in the HIV gene in patients changing antiretroviral drugs. We analyze such data from the HIV Drug Resistance Database at Stanford University using three data mining methods: association rule analysis, logistic regression, and classification trees. Although the AUC measures of the overall prediction is not high, these methods can effectively identify strong predictors of mutation change and focus further analysis by domain experts.

A combined data mining approach for infrequent events: analyzing HIV mutation changes based on treatment history

Many biological databases contain a large number of variables, among which events of interest may be very infrequent. Using a single data mining method to analyze such databases may not find adequate predictors. The HIV Drug Resistance Database at Stanford University stores sequential HIV-1 genotype-test results on patients taking antiretroviral drugs. We have analyzed the infrequent event of gene mutation changes by combining three data mining methods. We first use association rule analysis to scan through the database and identify potentially interesting mutation patterns with relatively high frequency. Next, we use logistic regression and classification trees to further investigate these patterns by analyzing the relationship between treatment history and mutation changes. Although the AUC measures of the overall prediction is not very high, our approach can effectively identify strong predictors of mutation change and thus focus the analytic efforts of researchers in verifying these results.

Diet, vegetarian food and prostate carcinoma among men in Taiwan

In a case–control study in a veterans hospital in Taiwan, we compared 237 histology-confirmed prostate carcinoma cases with 481 controls, frequency matched by age, for their consumption of vegetarian food, namely soybean products, rice, wheat protein and other vegetables. The multivariable logistic regression analysis showed a significant association with such food (odds ratio (OR)=0.67, 95% confidence interval (CI)=0.47, 0.94). This beneficial effect presented for men with body mass index (BMI) ⩽25 kg m⁻² (OR=0.50, 95% CI=0.32, 0.76) but not for men with greater BMI. The OR of prostate carcinoma for men with BMI ⩽25 kg m⁻² was 1.74 (95% CI=1.21, 2.51), compared with men with higher BMI (>25 kg m⁻²). Other significant risk factors associated with the disease included higher income (OR=2.40, 95% CI=1.07, 5.42), physical activity (OR=1.75, 95% CI=1.08, 2.83), being married (OR=2.49, 95% CI=1.40, 4.43) and coffee consumption (OR=1.88, 95% CI=1.07, 3.30). Stratified analysis also showed that the consumption of fish/shellfish had an adverse association for men with higher BMI. This study suggests that the intake of the low fat local vegetarian food has a protective effect against prostate carcinoma for thin men in this study population.

Peripheral blood cells among community residents living near nuclear power plants

Information about hematopoieses as a result of exposure to very low levels of radiation is scarce. To investigate the human hematopoietic effect of very low level radiation exposure, measurements of peripheral blood components were performed among 3602 men and women, aged 35 and above, living in a community near two nuclear power installations in Chinshan, Taiwan. The radiation level that each individual was exposed to was represented by a surrogate level, '1/D2(1i) + 1/D2(2i)', a transformed distance from each individual's residence to the two power plants D1 and D2. In addition to comparing average hematology measurements, multiple regression analyses were done to include age, gender, smoking, drinking status and the surrogate radiation exposure level as independent variables. Univariate and bivariate analyses showed that the hematology measurements had significant associations with age, gender, smoking or drinking. The multiple regression analyses revealed that significant positive associations with '1/D2(1i) + 1/D2(2i)' were found for hemoglobin, hematocrit, platelet, white blood cell and red blood cell. The platelet count might increase for 208.7 x 10(3)/microl if the exposure from the nuclear plants increased by one exposure unit. This type of association implies that those who lived closer to the nuclear power installation had a higher blood cell count; we suspect that this could be a type of radiation hormesis.

Pinworm control and risk factors of pinworm infection among primary-school children in Taiwan

Longitudinal pinworm (Enterobius vermicularis) infection rates were estimated at a mass screening for first-grade children during 1991-1996; children were provided medication at the screening. This campaign was able to decrease the infection rates for the 1991 cohort from 16.3% to 0.6%. A case-control study was further conducted for the investigation of risk factors among fourth-graders. Cases comprised 429 children with at least one infection between September 1996 to June 1999, and controls were 280 randomly selected uninfected classmates. Parents were asked to complete a questionnaire survey to report students' personnel hygiene habits. The case-control study revealed that significant factors associated with the infection included playing on the floor (odds ratio [OR], 2.5), nail biting (OR, 2.1), failure to wash hands before meals (OR, 1.7) and living in nonapartment dwellings (OR, 1.6). Girls were at a higher, but not significant, risk (OR, 1.4), than boys. In conclusion, inadequate personal hygiene increases the risk for pinworm infection. The mass screening-medication campaign can be adapted to countries with a similar parasitic problem.

TSG101 expression in gynecological tumors: relationship to cyclin D1, cyclin E, p53 and p16 proteins

Recent studies have shown that in vitro steady-state expression of the tumor susceptibility gene TSG101 is important for maintenance of genomic stability and cell cycle regulation. To determine the contribution of TSG101 expression in neoplastic formation, expression of TSG101 protein levels were evaluated in primary ovarian and endometrial adenocarcinoma tumors. Expression of TSG101 was also examined in various tumor cell lines (PA-1, AN3CA, HeLa, HS578T, HCT116). Full-length TSG101 protein was detected in these tumors and cell lines indicating that intragenic deletions were not characteristic of TSG101. In addition, TSG101 protein levels were compared with aberrations of prominent cell cycle regulatory molecules such as cyclin D1, cyclin E, p16 and p53. Reduced TSG101 protein was observed in 36% (8/22) of ovarian and 17% (1/6) of endometrial adenocarcinoma. Aberrant levels of p53, p16, cyclin D or E were comparable to published studies indicating that the clinicopathological distribution of these cases did not favor advanced stage tumors. Altogether, these findings suggest that a down-regulation of TSG101 is associated with tumorigenesis in a subgroup of gynecological tumors.

Role of urbanization and air pollution in adolescent asthma: a mass screening in Taiwan

BACKGROUND AND PURPOSE

The prevalence of asthma in school children in Taiwan is increasing. This study used mass screening among middle school children in Taiwan to determine the prevalence of asthma and related factors.

METHODS

Data were collected from parents using a self-reported questionnaire and from children using the International Study of Asthma and Allergies in Childhood (ISAAC) video questionnaire. Six study teams conducted the survey nationwide in 1995-1996, with the assistance of middle school nurses and teachers.

RESULTS

Among the 1,018,031 students at 795 middle schools who returned questionnaires, 8.5% had a history of asthma (ranging in prevalence from 4.2% to 13% in 25 areas). The prevalence of asthma was higher in boys than in girls (10.0% vs 7%) and was highest in more urbanized areas (11.2%), followed by moderately urbanized areas (7.4%) and less urbanized and rural areas (6.5%). Controlling for age, family smoking, family incense burning, and parental education level, multivariate logistic regression models indicated that children living in an area with heavy air pollution were more likely to have asthma than those in an area with no or light pollution (odds ratio, OR = 2.01 and 95% confidence interval, CI = 1.94-2.09 based on parental ranking of pollution level, or OR = 1.30 and 95% CI = 1.18-1.42 based on pollution level reported by the Environmental Protection Administration).

CONCLUSIONS

Adolescent asthma in Taiwan is most prevalent in the most urbanized areas and decreases in prevalence in less urbanized areas. This study also found that higher parental education level and higher area air pollution were associated with higher adolescent asthma prevalence.

Components of insulin resistance syndrome in a community-based population assessed by log-linear models

BACKGROUND AND PURPOSE

To investigate the clustering of insulin resistance syndrome with hyperinsulinemia, hypertriglyceridemia, low high-density lipoprotein (HDL) cholesterol, hypertension, and obesity, we conducted this cross-sectional study and analyzed the patterns of conditional independence among these five elements.

METHODS

Fasting insulin, lipid profiles, blood pressure, and anthropometric data from 2165 Taiwanese older than 35 years in the Chin-Shan community were examined. The cut-off points of these five factors (all binary variables) were defined. The hierarchical log-linear regression with nested effects model was applied to fit this higher-order contingency table of five variables, and likelihood ratio (chi2) statistics were used to test the goodness of fit.

RESULTS

Hyperinsulinemia was independently correlated with obesity (odds ratio [OR] 5.7, 95% confidence interval [CI] 4.5-7.3), low HDL (OR 2.3, 95% CI 1.8-2.9), and hypertriglyceridemia (OR 1.6, 95% CI 1.2-2.2). Hypertriglyceridemia was significantly associated with low HDL (OR 3.6, 95% CI 2.7-4.8), and non-significantly associated with hypertension (OR 1.3, 95% CI 0.9-1.7) and obesity (OR 1.1, 95% CI 0.8-1.6). In persons with normal triglyceride levels, hypertension was positively associated with obesity (OR 2.8, 95% CI 2.1-3.7) and low HDL (OR 2.0, 95% CI 1.5-2.8). Analyses from forward and backward selection methods gave similar results. Graphical models with conditional independence relationships among these five variables were demonstrated.

CONCLUSIONS

The components of insulin resistance syndrome have intricate relationships. Hyperinsulinemia was most related to obesity, and hypertriglyceridemia was most related to low HDL.

Coronary heart disease risk factors in urban bus drivers

The purpose of this study was to determine the risk factors for coronary heart disease (CHD) in 2297 bus drivers and skilled workers from the Taipei Municipal Bus Administrative Bureau. Data for this study were compiled from the medical records of annual physical examinations for bus drivers and skilled workers conducted at Taipei Municipal Chronic Disease Hospital during the period from July 1998 to June 1999. The results showed that, after adjustment for age, hypertension rates for bus drivers (56.0%, 986/1361) were significantly greater than for skilled workers (30.6%, 164/536). All age groups demonstrated a similar difference. Significant differences were also noted in body mass index, serum cholesterol, serum triglyceride and ischemic heart disease between bus drivers and skilled workers. Among bus drivers, the prevalence of obesity was 9.6%, hypercholesterolemia 34.0%, hypertriglyceridemia 69.4% and ischemic heart disease 1.7%. By contrast, among skilled workers, the prevalence of obesity was only 4.6%, hypercholesterolemia 29.9%, hypertriglyceridemia 30.6% and ischemic heart disease 0.9%. These findings suggest that exposure to the occupation of driving a bus may carry an increased risk of CHD and that drivers who develop signs of cardiovascular illness should be transferred to non-driving occupations within the company.

Drug-resistant tuberculosis in Taipei, 1996-1999

OBJECTIVES

To determine the trends, patterns, and risk factors associated with drug-resistant tuberculosis, we conducted a hospital-based retrospective study in Taipei.

METHODS

Clinical and bacteriologic data were routinely collected from 453 patients with a diagnosis of tuberculosis who were treated at Taipei Municipal Chronic Disease Hospital from January 1996 through December 1999 for whom drug-susceptibility testing was done.

RESULTS

Resistance to at least one drug was identified in 154 (34%) out of the 453 patients, and 34 (7.5%) patients were resistant to at least isoniazid and rifampin. Among the 199 patients with recurrent tuberculosis, 98 (49.2%) had isolates that showed resistance to at least one drug. Among the 254 new patients, 56 (22.0%) had isolates that were drug resistant. For all 453 patients, resistance to rifampin was most common (17.4%), followed by resistance to isoniazid (13.9%), streptomycin (13.7%), ethambutol (8.2%), and kanamycin (3.5%). A history of previous tuberculosis therapy (odds ratio = 9.4; 95% CI, 2.9-28) and being born outside of Taiwan (odds ratio 3.3; 95% CI, 1.1-34) were significant risk factors for multidrug resistance.

CONCLUSIONS

Our data suggest that the Taipei tuberculosis control program should be rapidly strengthened by expanded use of directly observed therapy and more careful bacteriologic and clinical follow-up, particularly in cases of recurrence and in persons born outside of Taiwan in tuberculosis endemic areas. Our results also indicate that the regular measuring of rates of drug resistance and the monitoring and guiding of tuberculosis treatment programs could increase the therapeutic response rate and prevent the appearance of newly acquired resistance in patients with tuberculosis. In addition, with high rifampin resistance (17.4%), the regulated market for rifampin is essential in Taiwan.

Serum leptin and leptin receptor isoforms in omental adipose tissue of nondiabetic women undergoing gynecologic surgery for benign disease

BACKGROUND AND PURPOSE

Leptin is important in the regulation of fat mass and body weight. Adipose tissue not only secretes leptin but also serves as a site of action for leptin. This study was designed to examine the relationships among tissue expression of leptin receptors, serum leptin, and body mass index.

METHODS

Omental adipose tissue and fasting blood samples were obtained from 57 nondiabetic women who underwent surgery for either myoma of the uterus or ovarian cyst. Tissue RNA was extracted using Trizol reagent and serum leptin concentrations were determined with commercial kits. The leptin receptor isoforms in tissues were quantified using real-time Taqman technology.

RESULTS

Three leptin receptor isoforms, Ob-Rb, HuB219.1, and HuB219.3, were found in human omental adipose tissue. The amounts of HuB219.1 and HuB219.3 mRNA relative to that of Ob-Rb were 1314.2 and 16.7, respectively. Higher body mass index was significantly correlated with an increase in serum leptin concentration and a decrease in leptin receptor HuB219.1 isoform in omental fat, even after adjustment for age and menopausal status. There was no direct association between serum leptin concentration and tissue HuB219.1 mRNA level.

CONCLUSIONS

HuB219.1 is the major isoform of leptin receptor expressed in human omental adipose tissue. Our findings suggest that the shorter leptin receptor isoforms in human omental adipose tissue might play an important role in body weight control. Further studies on the inter-relationship between leptin concentrations and multiple leptin receptor isoforms are needed to elucidate the exact mechanism of obesity.

Tuberculosis transmission in the family

OBJECTIVE

To evaluate the risk of tuberculosis (TB) transmission from family members with infectious TB to other family members, and to examine whether household contact investigations had an impact on tuberculosis patterns.

DESIGN

Under the direction of the Taipei Municipal Chronic Disease Hospital, 12 full-time public health nurses recruited the household contacts of TB patients. Chest X-ray examination was recommended for adult contacts. Child contacts received the Mantoux tuberculin skin test, and radiography was recommended if the results were positive.

SETTING

Family contacts of all TB index patients who attended one of 29 hospitals in Taipei, from July 1993 through June 1996. The medical records of index patients were obtained from the National Tuberculosis Registry.

RESULTS

During the study period, the families of 3903 index patients, comprising 11873 contacts, were investigated. Among these, 4595 received radiography, for a response rate of 38.7%. Of these, 284 had active pulmonary disease: 188 (66.3%) had minimal disease, 79 (27.8%) had moderately advanced disease, and only 17 (5.9%) had far advanced disease. Overall, the index patients had more advanced TB: only 1261 (32.3%) had minimal disease, while 2022 (51.8%) had moderately advanced disease and 620 (15.9%) had far advanced disease.

CONCLUSIONS

These data show a relatively high risk of intrafamily TB transmission. Our findings also show that family contact investigations may help to diagnose TB in earlier stages. Such an approach should greatly reduce the number of new TB cases and speed eradication of the disease.

Occupational exposures of pharmacists and pharmaceutical assistants to 60 Hz magnetic fields

We carried out the study to assess, using field surveys and personal dosimetry, the potential exposure of pharmacists and pharmaceutical assistants to 60 Hz magnetic fields in a medical center of Taiwan. Field surveys were conducted twice in the pharmacy where two workers were randomly selected and solicited to wear personal dosimetry instruments for a full-shift assessment of personal exposure. We used an EMDEX II for on site measurements and did not consider any specific instrument or equipment for health care services as potential sources of magnetic field. The results showed that the average magnetic flux densities for the selected areas were between 0.63 mill-Gauss (mG) and 2.23 mG, while the full-shift time-weighted-average exposure for the two selected workers was 4.98 mG and 6.54 mG, respectively. Both inadequate consideration for the field survey of the temporal variability in magnetic flux densities over the workday and that the monitored workers spent almost half of the full-shift working in places outside of the study areas may have contributed to such discrepancy in results between field survey and personal dosimetry. This study suggests that the potential for elevated exposure to 60 Hz magnetic fields in health care settings does exist, and that using job title as a surrogate for magnetic fields exposure classification might entail certain degrees of misclassification. Although limited in its scope and sample size, the study presented here seems to demonstrate the inadequacy of using stationary workplace measurements for the assessment of personal occupational exposure to 60 Hz magnetic fields.

Chin-Shan Community Cardiovascular Cohort in Taiwan-baseline data and five-year follow-up morbidity and mortality

A cohort consisting of 3602 residents (82.8% of the target population) aged 35 years and older was established in 1990 in the Chin-Shan Community, a suburb 20 miles outside of metropolitan Taipei, Taiwan. The long-term objective was to investigate the prospective impact on cardiovascular health in a society undergoing transition from a developing to a developed nation. This article presents the study design, selected baseline risk factors of cardiovascular diseases (CVD), and CVD events at the 5-year follow-up evaluation with an emphasis on sociodemographic differences. The multivariate logistic regression analyses revealed that white-collar individuals were more likely than blue-collar workers to have dyslipidemia including high-density lipoprotein cholesterol (HDL-C) levels <35 mg/dl [odds ratio (OR) = 1.7, 95% confidence interval (CI) = 1.2-2.4] and low-density lipoprotein cholesterol (LDL-C) levels >/=160 mg/dl (OR = 1.3, 95% CI = 1.0-1.7). However, they were at slightly lower risk for stroke and CVD/sudden death, and at moderately higher risk for coronary artery disease and diabetes, although both these trends were not significant. Men were more likely than women to have HDL-C levels <35 mg/dl (OR = 1.8, 95% CI = 1.4-2.2), but they were less likely to have LDL-C levels >/=160 mg/dl (OR = 0.7, 95% CI = 0.6-0.8). The risk of CVD/sudden death was higher for men than for women during the follow-up period (OR = 1.9, 95% CI = 1.3-2.9). This could be due to risk factors such as a much higher prevalence of tobacco (61.9% vs. 4.5%) and alcohol (43.7% vs. 6.4%) use in men. In conclusion, individuals of higher socioeconomic status have a higher prevalence of dyslipidemia but slightly lower 5-year incidence of CVD events.

Climate, traffic-related air pollutants, and asthma prevalence in middle-school children in taiwan

This study compared the prevalence of asthma with climate and air pollutant data to determine the relationship between asthma prevalence and these factors. We conducted a nationwide survey of respiratory illness and symptoms in middle-school students in Taiwan. Lifetime prevalences of physician-diagnosed asthma and of typical symptoms of asthma were compared to air monitoring station data for temperature, relative humidity, sulfur dioxide, nitrogen oxides, ozone, carbon monoxide, and particulate matter with aerodynamic diameter [less than/equal to] 10 microm (PM(10)). A total of 331,686 nonsmoking children attended schools located within 2 km of 55 stations. Asthma prevalence rates adjusted for age, history of atopic eczema, and parental education were associated with nonsummer (June-August) temperature, winter (January-March) humidity, and traffic-related air pollution, especially carbon monoxide and nitrogen oxides, for both girls and boys. Nonsummer temperature, winter humidity, and traffic-related air pollution, especially carbon monoxide and nitrogen oxides, were positively associated with the prevalence of asthma in middle-school students in Taiwan.

Association between indoor and outdoor air pollution and adolescent asthma from 1995 to 1996 in Taiwan

The study aim was to estimate the contribution of indoor and outdoor air pollution to the 1-year prevalence of adolescent asthma after personal susceptibility and other potential risk factors were taken into account. A large-scaled cross-sectional study was conducted among 165,173 high school students aged 11 to 16 years in the different communities of Kaohsiung and Pintong in Taiwan, from October 1995 to June 1996. Each student and his/her parents participating in the study completed a video and a written International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire about symptoms of wheezing and allergies, passive smoking, and demographic variables. After adjustment for potential confounders, adolescents exposed to cigarette smoking (odds ratio = 1.29, 95% confidence interval (CI), 1.17-1.42) and environmental tobacco smoke (odds ratio = 1.08, 95% CI, 1.05-1.12) were found to suffer from asthma at an increased frequency. We observed a statistically significant association between outdoor air pollution and asthma, after controlling for potential confound variables. Total suspended particulate, nitrogen dioxide, carbon monoxide, ozone, and airborne dust particles all displayed an independent association with asthma, respectively. There were no selection biases in this community-based study, which provides evidence that passive smoking and long-term, high average outdoor air pollution are independent risk factors of asthma.

Risk factors for prostate carcinoma in Taiwan: a case-control study in a Chinese population

BACKGROUND

Although prostate carcinoma remains a rare disease among Chinese men, its incidence is on the rise. The authors conducted a hospital-based case-control study to identify risk factors for prostate carcinoma in northern Taiwan.

METHODS

Patients at a selected veterans hospital or 2 military hospitals who were newly diagnosed with prostate carcinoma between August 1995 and July 1996 were included as cases (n = 90). Controls (n = 180) were comprised noncancer patients who were treated in emergency rooms and departments other than those of urology and cardiology at the same hospitals; controls were matched to cases by age (+/-5 years) and admission date (+/-4 months). Subjects were interviewed in person to elicit information regarding sociodemographic characteristics, life-style, diet, height, and weight.

RESULTS

Cases and controls were similar in terms of age and the majority of sociodemographic characteristics. However, cases tended to have received more education and were less likely to have blue-collar jobs than controls. The consumption of pork was moderately higher for cases than for controls, although this difference was not statistically significant. Cases were more likely than controls to engage in exercise (odds ratio [OR] = 2.16; 95% confidence interval [CI] = 1.18-3.96) and to have a body mass index > or = 24.75 kg/m2 at ages 40-45 years (OR = 2.00; 95%CI = 1.05-3.82). In addition, cases were less likely to cook vegetables with pork lard (OR = 0.47; 95%CI = 0.24-0.91).

CONCLUSIONS

The higher frequency of exercise and lower use of pork lard for cooking among cases reported in the current study suggest that cases tended to have relatively affluent life-styles compared with controls. Because less affluent families are likely to consume more vegetables than meat, these preliminary findings indicate that vegetable intake appears to have a protective effect.

Hyperinsulinemia and related atherosclerotic risk factors in the population at cardiovascular risk: a community-based study

BACKGROUND

A population-based study was conducted in Taiwan to investigate the prevalence of insulin resistance and high serum insulin concentrations and their relationships with potential atherosclerotic risk factors.

METHODS

We studied 2165 subjects, ages >35, from a community cohort.

RESULTS

The distributions of fasting insulin were skewed to the right, with higher concentrations in women than in men. As age increased, insulin increased in women, but decreased in men. As fasting insulin concentrations increased, postloading insulin, glucose, blood pressure, body mass index, waist-to-hip ratio, total cholesterol, triglycerides, LDL-cholesterol, apoprotein B, plasminogen activator inhibitor 1, tissue plasminogen activator, and fibrinogen increased, but lipoprotein(a), HDL-cholesterol, and apoprotein A1 decreased. Multiple logistic regression showed that obesity, high LDL-cholesterol, and low HDL-cholesterol were significant predictors of hyperinsulinemic status.

CONCLUSION

The study subjects with insulin resistance syndrome and related risk factors may be at risk for atherosclerosis, thrombosis, and other coronary heart diseases.

Lipoprotein (a) level in the population in Taiwan: relationship to sociodemographic and atherosclerotic risk factors

To examine the lipoprotein(a) (Lp(a)) level in the Taiwanese population and its association with cardiovascular risk factors, 1703 men and 1899 women aged 35 years and above were enrolled in a community-based study cohort established between 1990 and 1991. The distributions of Lp(a) levels were skewed to the right, and females were more likely than males to have Lp(a) levels greater than 30 mg/dl (14.3% versus 11.6%, P < 0.05). The Lp(a) level increased with age. Socioeconomic status did not seem to have consistent influence on the level of Lp(a). Smoking and alcohol use also had no effect on Lp(a) levels. Multivariate analysis indicated that older age and high level of low-density-lipoprotein cholesterol corresponded to an elevated Lp(a) level, while hypertriglyceridemia, low high-density-lipoprotein cholesterol level, obesity and high insulin resistance corresponded to a lower Lp(a) level. In univariate analysis, hyperinsulinemia was negatively associated with Lp(a) level (-0.107, P < 0.01) only in males. In females, use of oral contraceptive lowered Lp(a) levels, but menopause did not change Lp(a) levels. We also found that different correlation patterns existed for selected coagulation profiles between sexes. There was a significant correlation between Lp(a) and fibrinogen levels in males (0.154, P < 0.001) but not in females (0.007, P > 0.05). These data provided clues for investigating atherosclerotic risk factors and coagulation parameters for the Taiwanese population.

Risk assessment of active smoking: smoking-attributable mortality and years of potential life lost in Taiwan, 1980 and 1992

Anti-smoking programs have been advocated by the government and other private organizations for decades in Taiwan, especially in the past ten years. We conducted an analysis to assess the effectiveness of anti-smoking programs by examining the changes in active smoking attributable mortality (ASAM) and active smoking attributable years of potential life lost (ASAYPLL) between 1980 and 1992. This analysis also evaluated the present health impact due to active smoking. Total estimated ASAM was 12,765 for 1980 and 14,764 for 1992, representing 34.9% and 31.8% of all deaths from smoking-related causes for each year, respectively. Our results suggested a progress of anti-smoking efforts contributed by the government and other private anti-smoking organizations. By comparing the figures between 1980 and 1992, a reduction in all dimensions has been observed. The overall smoking prevalence rate decreased from 31.7% to 29.5% and the ASAM rate declined from 121.8/10(5) to 91.5/10(5). Additionally, the ASAYPLL rate declined from 513.4/10(5) to 406.9/10(5). Furthermore, the ratio of ASAM from cardiovascular diseases (CVD) to all ASAM decreased from 56.3% in 1980 to 46.7% in 1992, while the ratio of ASAM from cancer to all ASAM increased from 22.9% in 1980 to 34.9% in 1992. Our analysis also found that active smoking seemed to be a more important risk factor for smoking-related causes of death in people aged 41-65 than in people of other age group. Although the anti-smoking programs seemed effective over the past 13 years, active smoking still contributed to an estimated number of 14,764 deaths and 63,743 economically productive years lost in 1992. More efforts should be devoted to further reduce the high smoking prevalence in men and particularly to hamper the increasing smoking trend in adolescents and young women. This remains a challenge for the government of Taiwan.

Perinatal mortality in Taiwan

Information on perinatal deaths was obtained from 310 women by collecting detailed obstetric histories dating from marriage to the start of the survey. These histories were compared to those of 688 age matched controls. Potential risk factors, levels and time trends of perinatal mortality in Taiwan were examined and factors underlying stillbirths and early neonatal deaths were also compared using conditional logistic regression analyses. A nearly 56% decline of the perinatal mortality rate during the 35 y, approximately, prior to the survey was observed. Risk of stillbirths was increased among those who had abused illegal drugs during pregnancy, those who reported that the pregnancy was unwanted and those with Thalassemia trait. Body mass index was log-linearly related with stillbirths, with higher body mass associated with higher risk. For early neonatal deaths, those mothers aged 19 y or less, those giving birth to either their first children or to their fifth or later child, those who had their first prenatal care visit after the first three months of pregnancy were associated with increased risk in the logistic model. Those with a birth interval of less than two years and those with less education were associated with increased risk in both perinatal death groups. While some of these factors have already been associated with perinatal deaths, others have not; the new associations provide clues to mechanisms by which the risk of death increases before or after delivery.

Zinc is essential for binding of p56(lck) to CD4 and CD8alpha

Binding of the protein tyrosine kinase p56(lck) to T-cell co-receptors CD4 and CD8alpha is necessary for T-lymphocyte development and activation. Association of p56(lck) with CD4 requires two conserved cysteine residues in the cytosolic domain of CD4 and two in the amino terminus of p56(lck), consistent with the notion that these four residues coordinate a single metal atom (1-5). Here we demonstrate that Zn2+ is essential for complex formation. In an in vitro binding reaction, Zn2+ mediates p56(lck) association with a glutathione S-transferase (GST) fusion protein containing the cytosolic domains of CD4 or CD8alpha; no other metals tested support binding. Treatment of preformed GST-CD4.p56(lck) dimers with the Zn2+ chelators 1,10-O-phenanthroline or 8-hydroxyquinoline-5-sulfonic acid results in dissociation of GST-CD4 from p56(lck), consistent with the finding of Huse et al. (5) that Zn2+ is contained within similar complexes. Furthermore, we show that, within live cells, CD4.p56(lck) and CD8alpha.p56(lck) interactions occur in a zinc-dependent fashion. Specifically, pretreatment of the human Jurkat T-cell line with membrane permeable zinc chelators disrupts CD4.p56(lck) complexes, and treatment of COS cells co-expressing CD8alpha and p56(lck) with such chelators likewise leads to dissociation of CD8alpha.p56(lck) complexes. CD4. p56(lck) and CD8alpha.p56(lck) represent the first examples of intracellular proteins that require zinc as a bridge for heterodimerization.

Carboxy-terminal CFFL-sequence-specific monomeric protein geranylgeranyltransferase I from the eyes of the shrimp Penaeus japonicus

Protein geranylgeranyltransferase I from the eyes of Penaeus japonicus geranylgeranylates predominantly the sequence CFFL and Drosophila-specific Ras1 carboxyl termini, with the sequence CKML, as well as mammalian-specific G gamma carboxyl termini, with the sequence CAIL, but not the protein farnesyltransferase-specific sequence CVLS. The purified protein geranylgeranyltransferase I from shrimp was evidenced by immunoblotting and polyacrylamide gel electrophoresis under denaturing conditions to consist of single subunit of Mr 66,000 +/- 500. Since the active protein geranylgeranyltransferase I was found to have a relative mass of 67,000 +/- 1,000, the purified enzyme was deduced to be a monomer. The enzyme had an optimal pH of 8.0 with 100 mM Tris as the buffer and a K(m) of 7 +/- 2 microM with the synthetic peptide KCFFL as the substrate. The enzyme was inhibited by Zn++ and Mg++ ions at micromolar concentrations.

Urbanization and childhood leukaemia in Taiwan

BACKGROUND

In the 1980s socioeconomic development was dramatically rapid in the urbanized municipalities of Taiwan due to a prospering economy. This study addressed the question: Could differences in the incidence of childhood leukaemia (age <15) be demonstrated between urban and rural communities in Taiwan between 1981 and 1990?

METHODS

The log-linear regression model was used to assess the effects of age, level of urbanization, and calendar year on the variation of childhood leukaemia incidence rates between 1981 and 1990.

RESULTS

Between 1981 and 1990, the overall incidence rate of childhood leukaemia increased by 20% (rate ratio (RR) = 1.2, 95% CI: 1.0-1.5). As compared to rural areas, metropolitan regions showed a significantly higher incidence rate during the study period (RR = 1.3, 95% CI: 1.1-1.6). This urban-rural difference was particularly notable among children <5 years old (RR = 1.5, 95% CI: 1.2-1.9). Dose-response analysis further indicated that risk of childhood leukaemia was monotonically associated with levels of urbanization. The significant gradient in the risk of childhood leukaemia with urbanization was contributed solely by children in the 0-4 years age group.

CONCLUSIONS

We noticed a relationship between urbanization and risk of leukaemia in children. Because of a dramatic influx of people into metropolitan areas during the 1980s, our findings may have provided support for the putative association between 'population mixing' or 'population density' and risk of childhood leukaemia. Whether such association can be attributable to virus infection or other aetiologically related leukemogens warrants further investigations.

Oral contraceptives and breast cancer risk in Taiwan, a country of low incidence of breast cancer and low use of oral contraceptives

One hundred and seventy four (81% of all) pathologically confirmed new incident cases of female breast cancer identified from a medical center in Taipei from February, 1993 to June, 1994 were selected as the case group. Four hundred and fifty three inpatient controls who were without obstetric-gynecological, breast, or malignant diseases were individually matched for each case by age and date of admission. Information was obtained through direct interview and review of medical records. Conditional logistic regression was used to estimate the effects of each risk factor. After adjusting for education level, body mass index, age at menarche and first full-term pregnancy, parity, menopausal status and age at menopause, lifetime lactation, use of lactation inhibition hormones, and family history of breast cancer, breast cancer risk significantly elevated in use of OC before 25 years old and before 1971. In stratified analysis, significantly higher risk were found in OC use before 25 years old and in duration of use less than one year among post-menopausal subjects. Our results support the notion that OC use in early life for younger women and in early calendar years increase breast cancer risk.

Changes in platelet function and susceptibility of lipoproteins to oxidation associated with administration of aged garlic extract

Garlic and some of its organosulfur components have been found to be potent inhibitors of platelet aggregation in vitro. Demonstration of their efficacy in vivo, however, especially when administered over extended periods, is sparse. We recently performed a 10-month study comparing the effect of aged garlic extract (AGE) with placebo on the lipid profiles of moderately hypercholesterolemic men. In the course of the intervention trial, we examined platelet functions and susceptibility of lipoproteins to oxidation in a subgroup of this study population. Study subjects supplemented with 7.2 AGE per day showed a significant reduction of epinephrine- and, to a lesser degree, collagen-induced platelet aggregation but failed to demonstrate an inhibition of adenosine diphosphate (ADP)-induced aggregation. Platelet adhesion to fibrinogen, measured in a laminar flow chamber at moderately high shear rate, was reduced by approximately 30% in subjects taking AGE compared with placebo supplement. A trend toward decreased susceptibility of lipoproteins to oxidation also was noted during AGE administration compared with the placebo period. We conclude that the beneficial effect of garlic preparations on lipids and blood pressure extends also to platelet function, thus providing a wider potential protection of the cardiovascular system.

Sex difference in the mortality trends of acute myocardial infarction in Taiwan, 1974 to 1993

The mortality patterns of coronary heart disease (CHD) vary among countries. Although the mortality rates from this disease are decreasing in the majority of developed nations, most developing countries are experiencing upward trends, especially among men. The mortality trends of acute myocardial infarction (AMI) in Taiwan have not been reported. The purpose of this study was to investigate the effects of age, chronicle period, and birth cohort on the AMI mortality rates using computerized vital statistics data from 1974 through 1993. Compared with the age-adjusted AMI mortality rates in 1974, the mortality rates in 1993 were 2.4 times higher for men and 2.2 times higher for women. When the log-linear Poisson model was used to assess age, birth cohort, and chronicle period simultaneously, women had no elevated relative risk of dying from AMI in different periods. The relative risk of dying from AMI increased 2.5 times for men in the 1955-1959 birth cohort compared with those in the 1890-1894 birth cohort, while the relative risk for females declined by 3.7 times for the corresponding birth cohorts. Based on birth cohort, the trends in mortality differ substantially between sexes in Taiwan. These results may help to generate hypotheses regarding the possible factors, prevention, and control of mortality from AMI in Taiwan.

Risk of leukemia in children living near high-voltage transmission lines

We conducted a study to examine the risk of leukemia between 1987 and 1992 among children living near high-voltage transmission lines (HVTL) in three urban districts of northern Taiwan. Twenty-eight cases of leukemia among some 120,696 children aged 14 years or less were reported to the national cancer registry between 1987 and 1992. Compared with children living in households more than 100 meters away from HVTL, children living in households less than 100 meters from HVTL experienced an essentially elevated risk of leukemia (7 versus 2.88, standardized incidence ratio [SIR] = 2.43, 95% confidence interval [CI] = 0.98-5.01). The elevated risk stands when compared with all children of Taiwan alternatively (7 versus 2.60, SIR = 2.69, 95% CI = 1.08-5.55). Such elevated risk was particularly noteworthy among children aged 5-9 years. The findings suggest that children living near HVTL tend to experience an elevated risk of leukemia. Further investigations are undoubtedly needed to unveil whether such tendency may have implied the putative association between exposure to elevated magnetic fields and risk of childhood leukemia.

Body size as a factor in different ages and breast cancer risk in Taiwan

A matched case-control study was done on 175 pathologically proven new cases of female breast cancer from National Taiwan University Hospital from February 1993 to June 1994 and 457 hospital controls individually matched for age and date of admission. Height and weight during one year before the first full-term pregnancy and one year before admission were collected from a questionnaire interview. Body mass index (BMI) (kg/m2) was derived accordingly. Demographic and reproductive characteristics, and family history of breast cancer were collected and adjusted as potential confounders. Conditional multiple logistic regression analysis was used to estimate the effect for each risk factor regarding body size of different ages. After adjustment for potential confounders, higher weight and BMI during one year before first full-term pregnancy were associated with a moderately lower risk of breast cancer especially in the premenopausal group. The heaviest group (> or = 65 kg) during one year before admission also had a moderately lower breast cancer risk. Height did not show any significant association with breast cancer risk. Weight and BMI gain were associated with an elevated breast cancer risk in the postmenopausal group but with wide confidence limits. The results of this study imply that adipose tissue may interfere with ovarian endocrine in the younger age group, and that there is increased hormonal production after obvious weight gain.

A validity analysis of residential magnetic fields estimated from high-voltage transmission lines

Between November 1994 and May 1995, indoor power frequency magnetic fields of 407 residences in northern Taiwan were assessed by short-term on site measurements and by modeling computerized power lines information from high-voltage transmission lines. The study residences were selected according to the distance from the transmission lines with cutoff points of 50 meters (m), 100 m, and 150 m, which gave rise to four categories of residences. The analysis showed that the measured magnetic fields were higher than the calculated magnetic fields for most residences, especially for those with lower measured magnetic fields. The measured and calculated magnetic fields showed an agreement of 0.93 (intra-class correlation coefficient, [ICC] = 0.93) for the residences within 50 m of the transmission lines. The ICC declined with the distance from the transmission lines with a lowest ICC of 0.42 for the residences located more than 149 m away from power lines. When both measured and calculated magnetic fields were categorized into three levels with cutoff points of 1 milligauss (mG) and 2 mG, the indices of agreement were very similar for the three residential categories within 149 m of the lines with Kappa (K) between 0.51 and 0.55. The K for the residences more than 149 m from the lines was low at 0.29. The ICC and K observed from a reduced sample of 114 residences presumably representative of all residences in northern Taiwan with respect to the distribution of household magnetic fields was 0.90 and 0.64, respectively. Our data show that using exclusively computerized power lines information to assess residential magnetic fields exposure entails a certain degree of exposure misclassification, but in the absence of direct measurement, this way of doing provides reasonable estimates of magnetic fields exposure within 100 m of transmission lines.

Age-period-cohort analysis of cervical cancer mortality in Taiwan, 1974-1992

OBJECTIVES

To develop a hypothesis about the carcinogenesis of cervical cancer from a descriptive analysis.

METHODS

The mortality data of cervical cancer were analyzed over the period from 1974 to 1992 among Taiwanese women using a log-linear Poisson model modified from the method of Osmond and Gardner to examine the effects of age, calendar period of death, and birth cohort on cervical cancer mortality.

RESULTS

This age-period-cohort model provides a summary guide for interpretation of cancer mortality trends. According to this model, age was found to be the strongest factor predicting cervical cancer mortality. Women in 50-54 age group have 89.3-fold risk of cervical cancer compared to those in the 30-34 age group. The cohort effect is also of particular interest because the generation at greatest risk for cervical cancer is the one born between 1893 and 1938, and a dramatically declining trend is observed thereafter for 1938-1963 birth cohort. Interest has emerged about the increasing trend in recent cohorts (after 1963 birth cohort). However calendar time only has a slight effect in the APC analysis. The model also identified a possible role of female sex hormones as the age effect, promiscuous sexual activity as the period effect (promoter) and the change in reproductive behavior as the cohort effect (initiator).

CONCLUSIONS

These results may help to develop a hypothesis of carcinogenesis of cervical cancer in Taiwan.

Residential exposure to 60-Hertz magnetic fields and adult cancers in Taiwan

We conducted a case-control study, using matching on date of birth, sex, and date of diagnosis, in northern Taiwan to evaluate the risks of adult leukemia, brain tumors, and female breast cancers in relation to residential exposure to 60-Hertz (Hz) magnetic fields. Cases were persons with newly diagnosed cancers reported to the cancer registry between 1987 and 1992, and controls were persons with cancers sites other than those previously suspected of being associated with magnetic fields. Magnetic fields in the residences occupied by the study subjects at the time of diagnosis were estimated from high-voltage transmission lines. The results were based on the separate analysis of 870 cases of leukemia, 577 brain tumors, and 1,980 female breast cancers. We estimated the risk of leukemia among those exposed to magnetic fields of > 0.2 microtesla (microT), relative to the risk among those exposed to fields of < 0.1 microT; the odds ratio was 1.4 [95% confidence interval (CI) = 1.0-1.9]. For distance < 50 meters relative to > or = 100 meters, the relative risk was 2.0 (95% CI = 1.4-2.9). For brain tumors and female breast cancers, the odds ratios were close to unity.

Epidemiology of cervical cancer in Taiwan

Because the prevalence of several risk factors for cervical cancer, including sexual behavior, reproductive patterns, contraceptive use, and cigarette smoking, has changed significantly over time among Taiwanese women, it is of interest to analyze the impact of these trends on the incidence and mortality rates for this cancer during the decades between 1970 and 1990. The number of deaths from cervical cancer was obtained from the Taiwan Provincial Department of Health during the period from 1974 to 1992. Data of all incident cervical cancer cases from 1979 through 1990 obtained from the Taiwan Cancer Registry were also used for the analyses. The trends in the age-adjusted and age-specific rates were examined. Age, period, and cohort effects on the incidence and mortality rates were also examined, using age-period-cohort (APC) models. The age-adjusted mortality rate has been increasing since the 1970s, particularly in both the youngest group (20-29 years) and the oldest group (65 years and over). While the age-adjusted incidence rate decreased from 1979 to 1990, and decreases were apparent across all broad age groups, nevertheless, the incidence of adenocarcinoma was moderating during the same time period. The APC models disclosed a decreasing cohort effect for the mortality and incidence rates among women born after 1936. Decreasing incidence rates after menopause were more consistent with a hormonal effect than a cohort effect. Declining trends in cervical cancer incidence may be related to the screening practices which may have counteracted the increasing prevalence of several risk factors, although poor survival influenced the incidence/mortality differentials for cervical cancer. Continued surveillance is warranted; however, attention might be directed to the trends in cervical adenocarcinoma.

Epidemiological appraisal of studies of residential exposure to power frequency magnetic fields and adult cancers

OBJECTIVES

To appraise epidemiological evidence of the purported association between residential exposure to power frequency magnetic fields and adult cancers.

METHODS

Literature review and epidemiological evaluation.

RESULTS

Seven epidemiological studies have been conducted on the risk of cancer among adults in relation to residential exposure to power frequency magnetic fields. Leukaemia was positively associated with magnetic fields in three case-control studies. The other two case-control studies and two cohort studies did not show such a link. Brain tumours and breast cancer have rarely been examined by these studies. Based on the epidemiological results, the analysis of the role of chance and bias, and the criteria for causal inferences, it seems that the evidence is not strong enough to support the putative causal relation between residential exposure to magnetic fields and adult leukaemia, brain tumours, or breast cancer. Inadequate statistical power is far more a concern than selection bias, information bias, and confounding in interpreting the results from these studies, and in explaining inconsistencies between studies.

CONCLUSIONS

Our reviews suggested that the only way to answer whether residential exposure to magnetic fields is capable of increasing the risks of adult cancers is to conduct more studies carefully avoiding methodological flaws, in particular small sample size. We also suggested that the risk of female breast cancer should be the object of additional investigations, and that future studies should attempt to include information on exposure to magnetic fields from workplaces as well as residential exposure to estimate the effects of overall exposure to magnetic fields.