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Biomedical subjects

L Kan

Publications and source records attributed to L Kan.

44 records · Page 3Linked to original sources
PubMed1986

Childhood and recent eating patterns and risk of breast cancer.

A case-control study was done to examine the relationship between childhood and recent eating practices and risk of breast cancer. Eight hundred forty-six cases and 862 controls returned questionnaires indicating their menopausal status. In premenopausal women, breast cancer risk was increased with recent consumption of foods high in fat content (gravy, beef, pork) and reduced with foods low in fat content (fish); in postmenopausal women, risk was increased with pork consumption only. Regarding carotene sources, risk was reduced with carrot consumption in postmenopausal women only. Similar trends in risk were not found for childhood eating practices. Body weight influenced the breast cancer risk differently for pre- and postmenopausal women: Heavier weight in childhood and teens reduced the risk of premenopausal breast cancer, and heavier weight in adulthood increased the risk of postmenopausal breast cancer. We conclude that fat consumption is associated with breast cancer, especially in premenopausal women.

Adult↗
PubMed1983

Purification and characterization of the heat-stable factors essential for the conversion of lignoceric acid to cerebronic acid and glutamic acid: identification of N-acetyl-L-aspartic acid.

The conversion of lignoceric acid to cerebronic acid, ceramides, cerebrosides, and glutamic acid is catalyzed by a rat brain particulate preparation. The heat-stable factor, prepared from calf cerebellum, together with the heat-labile factor, a pyridine nucleotide, and Mg2+ are essential to all of these metabolic pathways. Our previous work showed that the heat-stable factor is composed of at least two components, HSF-1 and HSF-2, and identified HSF-2 as D-glucose-6-phosphate. In the current investigation, HSF-1 was further purified and found to be N-acetyl-L-aspartic acid. In addition, it was discovered that a third component, HSF-3, is also required for heat-stable factor activity. A reconstituted system composed of N-acetylaspartic acid, glucose-6-phosphate, and HSF-3 fully replaced the heat-stable factor essential for the conversion of lignoceric acid to cerebronic acid and glutamic acid. The reconstituted heat-stable factor did not show the initial time lag always observed with the crude heat-stable factor.

Animals↗
PubMedDate not supplied

Computer programming for nucleic acid studies. II. Total chemical shifts calculation of all protons of double-stranded helices.

A FORTRAN computer program called SHIFTS is described. Through SHIFTS, one can calculate the NMR chemical shifts of the proton resonances of single and double-stranded nucleic acids of known sequences and of predetermined conformations. The program can handle RNA and DNA for an arbitrary sequence of a set of 4 out of the 6 base types A,U,G,C,I and T. Data files for the geometrical parameters are available for A-, A'-, B-, D- and S-conformations. The positions of all the atoms are calculated using a modified version of the SEQ program [1]. Then, based on this defined geometry three chemical shift effects exerted by the atoms of the neighboring nucleotides on the protons of each monomeric unit are calculated separately: the ring current shielding effect: the local atomic magnetic susceptibility effect (including both diamagnetic and paramagnetic terms); and the polarization or electric field effect. Results of the program are compared with experimental results for a gamma (ApApGpCpUpU) 2 helical duplex and with calculated results on this same helix based on model building of A'-form and B-form and on graphical procedure for evaluating the ring current effects.

Base Sequence↗
PubMedDate not supplied

Computer programming for nucleic acid studies. III. Calculated ultraviolet absorption spectra of protected oligodeoxyribonucleotides.

A computer program called UV. FOR was written in FORTRAN. This program primarily utilizes the digitized UV absorption spectra of 8 protected deoxyribonucleosides in 95% ethanol solution to compose the UV spectrum of a oligodeoxynucleotide of any sequence. Both calculated and observed UV spectra of 2 protected oligodeoxynucleotides are carefully compared. The results show that the calculated UV spectrum is virtually identical to the observed spectrum. Thus, the calculated spectra provide rapid confirmation of oligonucleotide compositions during the course of oligonucleotide synthesis by the phosphotriester method.

Computers↗
PubMedDate not supplied

Waiting for a diagnosis after an abnormal screening mammogram. SMPBC diagnostic process workgroup. Screening Mammography Program of British Columbia.

BACKGROUND: Women with abnormal screening mammograms require diagnostic assessment and experience anxiety until a diagnosis is established. This report evaluated the timeliness of diagnosis after an abnormal screening mammogram in the Screening Mammography Program of British Columbia (SMPBC). METHODS: Information on diagnostic interventions following an abnormal screen (N = 10,314) provided through 11 regional SMPBC services between January 1, 1993 and June 30, 1994 were abstracted and analyzed. RESULTS: The median time from abnormal screen to diagnosis was 3.4 weeks with regional variation of 2.0 to 4.7 weeks; 10% waited 8.7 weeks or longer. For the 19% of women proceeding to open biopsy, the median diagnostic interval was 7.1 weeks with regional variation of 4.6 to 9.3 weeks; 10% waited 13.1 weeks or longer. INTERPRETATION: After an abnormal screening mammogram, women waited many weeks for a definitive diagnosis, especially those proceeding to open biopsy. Opportunities for process improvement were identified.

Breast Neoplasms↗
PubMedDate not supplied

Improving the time to diagnosis after an abnormal screening mammogram.

INTRODUCTION: Five community-specific interventions to reduce the time to diagnosis after an abnormal breast screen have been evaluated. METHODS: Subjects with abnormal screening mammograms in 1998 were assessed through five community pilot projects (N = 1137) and a control random sample assessed elsewhere in BC (N = 1053). The number, types, dates and physician costs of breast-related interventions after an abnormal screen were compared between pilots and control. RESULTS: The median time to diagnosis for women without a biopsy was reduced from 23 days to 7 days (p = 0.001) in the pilot with facilitated referral to diagnosis. The median time to diagnosis for women with a biopsy was reduced from 57 days to 22-43 days in the pilots. Median physician costs per subject were lower (p = 0.02) in pilots that more frequently used core biopsy to obtain a diagnosis. CONCLUSIONS: Process changes can improve the time to diagnosis after an abnormal breast screen, with similar or lower physician costs per subject. Facilitating the referral process had the greatest impact.

Adult↗
PubMedDate not supplied

Compliance with the screening mammography program of British Columbia: will she return?

OBJECTIVE: To identify factors associated with compliance in the Screening Mammography Program of British Columbia (SMPBC). METHOD: Factors associated with rescreening within 18 months (annual compliers) and between 18 to 36 months later (late compliers) were identified in a cohort of SMPBC screenees using a self-administered questionnaire. RESULTS: Fewer than half of women initially screened within the SMPBC were annual compliers, nearly 40% not returning by 3 years. In women age 50+ years, annual compliers tended to have no prior mammography, no prior breast pain, a physician referral to SMPBC, and a normal initial SMPBC mammogram. Late compliers also tended to have no prior mammography, a physician referral, and a normal initial SMPBC mammogram. CONCLUSIONS: Several modifiable factors associated with compliance were identified: a physician referral to the program and possibly subsequent referral back to the program after workup for an abnormal mammogram.

Adult↗