Patients' understanding of how genotype variation affects benefits of tamoxifen therapy for breast cancer.

Background: CYP2D6 is a critical enzyme in the metabolism of tamoxifen and potentially a key determinant in breast cancer outcomes. Our study examined patients' beliefs about how the CYP2D6 genotype would affect their prognoses.

Methods: Women enrolled in a pharmacogenomic clinical trial and on tamoxifen for prevention or treatment of breast cancer underwent CYP2D6 genotyping (EM = extensive, IM = intermediate, PM = poor metabolizing alleles).

Patient navigation and the quality of breast cancer care: an analysis of the breast cancer care quality indicators.

Purpose: Patient navigation programs are initiated to help guide patients through barriers in a complex cancer care system. We sought to analyze the impact of our patient navigator program on the adherence to specific Breast Cancer Care Quality Indicators (BCCQI).

Methods: A retrospective cohort of patients with stage I-III breast cancer seen the calendar year prior to the initiation of the patient navigation program were compared with patients treated in the ensuing two calendar years.

Genotype-guided tamoxifen dosing increases active metabolite exposure in women with reduced CYP2D6 metabolism: a multicenter study.

Purpose: We examined the feasibility of using CYP2D6 genotyping to determine optimal tamoxifen dose and investigated whether the key active tamoxifen metabolite, endoxifen, could be increased by genotype-guided tamoxifen dosing in patients with intermediate CYP2D6 metabolism.

Patients And Methods: One hundred nineteen patients on tamoxifen 20 mg daily ≥ 4 months and not on any strong CYP2D6 inhibiting medications were assayed for CYP2D6 genotype and plasma tamoxifen metabolite concentrations. Patients found to be CYP2D6 extensive metabolizers (EM) remained on 20 mg and those found to be intermediate (IM) or poor (PM) metabolizers were increased to 40 mg daily.

Algebraic determination of the principal refractive indices and axes in the electro-optic effect.

A systematic algebraic approach is presented as a preferred alternative to an iterative numerical method for deriving expressions for the principal refractive indices and dielectric axes of a nonmagnetic crystal in a uniform electric field. This approach is applicable for an arbitrary field and for any symmetry point group. The results, to the chosen order in the field, are expressed algebraically in terms of measurable crystal tensors.

Traceless multipole moment densities and transformations in macroscopic electromagnetism.

We consider whether use of traceless multipole moment densities in macroscopic electromagnetism can yield physically acceptable results. For harmonic plane wave fields it is shown that a traceless electric quadrupole density yields linear constitutive relations for which the dynamical material constants (permittivity and magnetoelectric coefficients) and response fields are unphysical. We further show that, within multipole theory, these constitutive relations cannot be transformed into physically acceptable relations.

Application of the Jones calculus for a modulated double-refracted light beam propagating in a homogeneous and nondepolarizing electro-optic uniaxial crystal.

The Jones matrix calculus is applied to an electro-optic crystal with uniaxial symmetry when the light beam is incident nearly normally on the crystal face. The approach allows one to treat refracted waves and rays that diverge in the crystal and are modulated by an external low-frequency field. The effect of partial interference of overlapping refracted beams is allowed for and calculated for the case of uniform intensity of the beam over its cross section.

Analysis of accuracy of measurement of quadratic electro-optic coefficients in uniaxial crystals: a case study of KDP.

Taking KDP as an example of a uniaxial crystal, we analyze contributions to its quadratic electro-optic response with a view to explaining differences in published values of certain quadratic coefficients. In an eigenvalue theory of light propagation we show that the linear electro-optic coefficient contributes to the quadratic response, even under ideal laboratory conditions. In addition, the effect of imperfect crystal cutting and alignment is investigated by means of computer calculations based on the Jones calculus.

Effect of beam divergence from the optic axis in an electro-optic experiment to measure an induced Jones birefringence.

Certain optical properties can be described in terms of two linear birefringences existing in separate Jones platelets of a medium. One of these, known as Jones birefringence, although occurring naturally in some crystals is too small to be measurable. However, the two birefringences can be induced by an electric field in 4 and 6 crystals for propagation along the optic axis.