893 resultados para group-theoretical methods
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Background Men who have sex with men (MSM) remain the group most at risk of acquiring HIV infection in Britain. HIV prevalence appears to vary widely between MSM from different ethnic minority groups in this country for reasons that are not fully understood. The aim of the MESH project was to examine in detail the sexual health of ethnic minority MSM living in Britain. Methods/Design The main objectives of the MESH project were to explore among ethnic minority MSM living in Britain: (i) sexual risk behaviour and HIV prevalence; (ii) their experience of stigma and discrimination; (iii) disclosure of sexuality; (iv) use of, and satisfaction with sexual health services; (v) the extent to which sexual health services (for treatment and prevention) are aware of the needs of ethnic minority MSM. The research was conducted between 2006 and 2008 in four national samples: (i) ethnic minority MSM living in Britain; (ii) a comparison group of white British MSM living in Britain; (iii) NHS sexual health clinic staff in 15 British towns and cities with significant ethnic minority communities and; (iv) sexual health promotion/HIV prevention service providers. We also recruited men from two "key migrant" groups living in Britain: MSM born in Central or Eastern Europe and MSM born in Central or South America. Internet-based quantitative and qualitative research methods were used. Ethnic minority MSM were recruited through advertisements on websites, in community venues, via informal networks and in sexual health clinics. White and "key migrant" MSM were recruited mostly through Gaydar, one of the most popular dating sites used by gay men in Britain. MSM who agreed to take part completed a questionnaire online. Ethnic minority MSM who completed the online questionnaire were asked if they would be willing to take part in an online qualitative interview using email. Service providers were identified through the British Association of Sexual Health and HIV (BASHH) and the Terrence Higgins Trust (THT) CHAPS partnerships. Staff who agreed to take part were asked to complete a questionnaire online. The online survey was completed by 1241 ethnic minority MSM, 416 men born in South and Central America or Central and Eastern Europe, and 13,717 white British MSM; 67 ethnic minority MSM took part in the online qualitative interview. In addition 364 people working in sexual health clinics and 124 health promotion workers from around Britain completed an online questionnaire. Discussion The findings from this study will improve our understanding of the sexual health and needs of ethnic minority MSM in Britain.
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Background. To explore effects of a health risk appraisal for older people (HRA-O) program with reinforcement, we conducted a randomized controlled trial in 21 general practices in Hamburg, Germany. Methods. Overall, 2,580 older patients of 14 general practitioners trained in reinforcing recommendations related to HRA-O-identified risk factors were randomized into intervention (n = 878) and control (n = 1,702) groups. Patients (n = 746) of seven additional matched general practitioners who did not receive this training served as a comparison group. Patients allocated to the intervention group, and their general practitioners, received computer-tailored written recommendations, and patients were offered the choice between interdisciplinary group sessions (geriatrician, physiotherapist, social worker, and nutritionist) and home visits (nurse). Results. Among the intervention group, 580 (66%) persons made use of personal reinforcement (group sessions: 503 [87%], home visits: 77 [13%]). At 1-year follow-up, persons in the intervention group had higher use of preventive services (eg, influenza vaccinations, adjusted odds ratio 1.7; 95% confidence interval 1.4–2.1) and more favorable health behavior (eg, high fruit/fiber intake, odds ratio 2.0; 95% confidence interval 1.6–2.6), as compared with controls. Comparisons between intervention and comparison group data revealed similar effects, suggesting that physician training alone had no effect. Subgroup analyses indicated favorable effects for HRA-O with personal reinforcement, but not for HRA-O without reinforcement. Conclusions. HRA-O combined with physician training and personal reinforcement had favorable effects on preventive care use and health behavior.
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Comparison of the crystal structure of a transition state analogue that was used to raise catalytic antibodies for the benzoyl ester hydrolysis of cocaine with structures calculated by ab initio, semiempirical, and solvation semiempirical methods reveals that modeling of solvation is crucial for replicating the crystal structure geometry. Both SM3 and SM2 calculations, starting from the crystal structure TSA I, converged on structures similar to the crystal structure. The 3-21G(*)/HF, 6-31G*/HF, PM3, and AM1 calculations converged on structures similar to each other, but these gas-phase structures were significantly extended relative to the condensed phase structures. Two transition states for the hydrolysis of the benzoyl ester of cocaine were located with the SM3 method. The gas phase calculations failed to locate reasonable transition state structures for this reaction. These results imply that accurate modeling of the potential energy surfaces for the hydrolysis of cocaine requires solvation methods.
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Non-invasive vascular studies can provide crucial information on the presence, location, and severity of critical limb ischaemia (CLI), as well as the initial assessment or treatment planning. Ankle-brachial index with Doppler ultrasound, despite limitations in diabetic and end-stage renal failure patients, is the first-line evaluation of CLI. In this group of patients, toe-brachial index measurement may better establish the diagnosis. Other non-invasive measurements, such as segmental limb pressure, continuous-wave Doppler analysis and pulse volume recording, are of limited accuracy. Transcutaneous oxygen pressure (TcPO(2)) measurement may be of value when rest pain and ulcerations of the foot are present. Duplex ultrasound is the most important non-invasive tool in CLI patients combining haemodynamic evaluation with imaging modality. Computed tomography angiography (CTA) and magnetic resonance angiography (MRA) are the next imaging studies in the algorithm for CLI. Both CTA and MRA have been proven effective in aiding the decision-making of clinicians and accurate planning of intervention. The data acquired with CTA and MRA can be manipulated in a multiplanar and 3D fashion and can offer exquisite detail. CTA results are generally equivalent to MRA, and both compare favourably with contrast angiography. The individual use of different imaging modalities depends on local availability, experience, and costs. Contrast angiography represents the gold standard, provides detailed information about arterial anatomy, and is recommended when revascularisation is needed.
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We present a combined experimental and theoretical study of the electronic transport through single-molecule junctions based on nitrile-terminated biphenyl derivatives. Using a scanning tunneling microscope-based break-junction technique, we show that the nitrile-terminated compounds give rise to well-defined peaks in the conductance histograms resulting from the high selectivity of the N-Au binding. Ab initio calculations have revealed that the transport takes place through the tail of the LUMO. Furthermore, we have found both theoretically and experimentally that the conductance of the molecular junctions is roughly proportional to the square of the cosine of the torsion angle between the two benzene rings of the biphenyl core, which demonstrates the robustness of this structure-conductance relationship.
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A combined spectroscopic and ab initio theoretical study of the doubly hydrogen-bonded complex of 2-pyridone (2PY) with NH3 has been performed. The S-1 <- S-0 spectrum extends up to approximate to 1200 cm(-1) above the 0(0)(0) band, close to twice the range observed for 2PY. The S-1 state nonradiative decay for vibrations above approximate to 300 cm(-1) in the NH3 complex is dramatically slowed down relative to bare 2PY. Also, the Delta v=2,4,... overtone bands of the v(1)' and v(2)' out-of-plane vibrations that dominate the low-energy spectral region of 2PY are much weaker or missing for 2PY center dot NH3, which implies that the bridging (2PY)NH center dot center dot center dot NH3 and H2NH center dot center dot center dot O=C H-bonds clamp the 2PY at a planar geometry in the S-1 state. The mass-resolved UV vibronic spectra of jet-cooled 2PY center dot NH3 and its H/D mixed isotopomers are measured using two-color resonant two-photon ionization spectroscopy. The S-0 and S-1 equilibrium structures and normal-mode frequencies are calculated by density functional (B3LYP) and correlated ab initio methods (MP2 and approximate second-order coupled-cluster, CC2). The S-1 <- S-0 vibronic assignments are based on configuration interaction singles (CIS) and CC2 calculations. A doubly H-bonded bridged structure of C-S symmetry is predicted, in agreement with that of Held and Pratt [J. Am. Chem. Soc. 1993, 115, 9718]. While the B3LYP and MP2 calculated rotational constants are in very good agreement with experiment, the calculated H2NH center dot center dot center dot O=C H-bond distance is approximate to 0.7 angstrom shorter than that derived by Held and Pratt. On the other hand, this underlines their observation that ammonia can act as a strong H-bond donor when built into an H-bonded bridge. The CC2 calculations predict the H2NH center dot center dot center dot O distance to increase by 0.2 angstrom upon S-1 <- S-0 electronic excitation, while the (2PY)NH center dot center dot center dot NH3 H-bond remains nearly unchanged. Thus, the expansion of the doubly H-bonded bridge in the excited state is asymmetric and almost wholly due to the weakening of the interaction of ammonia with the keto acceptor group.
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Adjuvant chemotherapy decisions in breast cancer are increasingly based on the pathologist's assessment of tumor proliferation. The Swiss Working Group of Gyneco- and Breast Pathologists has surveyed inter- and intraobserver consistency of Ki-67-based proliferative fraction in breast carcinomas. Methods Five pathologists evaluated MIB-1-labeling index (LI) in ten breast carcinomas (G1, G2, G3) by counting and eyeballing. In the same way, 15 pathologists all over Switzerland then assessed MIB-1-LI on three G2 carcinomas, in self-selected or pre-defined areas of the tumors, comparing centrally immunostained slides with slides immunostained in the different laboratoires. To study intra-observer variability, the same tumors were re-examined 4 months later. Results The Kappa values for the first series of ten carcinomas of various degrees of differentiation showed good to very good agreement for MIB-1-LI (Kappa 0.56–0.72). However, we found very high inter-observer variabilities (Kappa 0.04–0.14) in the read-outs of the G2 carcinomas. It was not possible to explain the inconsistencies exclusively by any of the following factors: (i) pathologists' divergent definitions of what counts as a positive nucleus (ii) the mode of assessment (counting vs. eyeballing), (iii) immunostaining technique, and (iv) the selection of the tumor area in which to count. Despite intensive confrontation of all participating pathologists with the problem, inter-observer agreement did not improve when the same slides were re-examined 4 months later (Kappa 0.01–0.04) and intra-observer agreement was likewise poor (Kappa 0.00–0.35). Conclusion Assessment of mid-range Ki-67-LI suffers from high inter- and intra-observer variability. Oncologists should be aware of this caveat when using Ki-67-LI as a basis for treatment decisions in moderately differentiated breast carcinomas.
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This thesis focuses on “The “great hunting” among the Baka pygmies of the Southeastern Cameroon. A contribution to Anthropology of environment. The problematic in the study is the confrontation of great hunting among the Baka with the institutional, socio-economic and ecological change in forest. The goal is to analyze the mechanisms of adaptation of this game against these changes that affect the Baka environment. The proposed hypothesis suggests that Baka Pygmies have restructured the preparatory ceremonies of the great hunting following changes that occurred in their environmental milieu. Certain ritual animals have been substituted. Hunting lands, tools, methods and periods were also modified. The great hunting is opened to Baka hunters and non Baka hunters. Qualitative techniques, including observation, interviews and focus group discussions were used for data collection. The observations allowed us to understand the reality of driving forces in the forest as well as tools for hunting, hunting land and even the species sought. Interviews and focus group discussions were consolidated data on the ancient practice of hunting for rituals like Jengi and Beka, on the current practice of this hunting and on the impact of the of the modification of this hunting practice on the Baka culture. The results of this research show that the Baka have taken important measure to adapt their great hunting to the changing time and space. But the restructuring of this hunting varies from one village to another. As and when we leave the depths of the forest to the city of Yokadouma the great hunting is practiced less and less. Baka use illegal hunting tools and even fully protected species in their great hunting and in rituals celebrations. The overexploitation of forest resources, the creation of protected areas, full protection of certain large mammals and the action of ecoguards are something of an obstacle to the ancient practice of hunting for ritual. In most of camp where hunting is no more existing, ritual ceremonies are less and less celebrated. The study is divided into five chapters. The first chapter is related to the literature review, the theoretical framework, the definition of concepts, the second focuses on the geographical presentation of the study area, the third chapter looks at factors affecting the great hunting, the fourth chapter deal with the changes observed in the Baka’s great hunting, and the fifth chapter examines consequences of the restriction or suppression of the hunt on the Baka socio culture.
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Parents and children, starting at very young ages, discuss religious and spiritual issues¿where we come from, what happens to us after we die, is there a God, and so on. Unfortunately, few studies have analyzed the content and structure of parent-child conversation about religion and spirituality (Boyatzis & Janicki, 2003; Dollahite & Thatcher, 2009), and most studies have relied on self-report with no direct observation. The current study examined mother-child (M-C) spiritual discourse to learn about its content, structure, and frequency through a survey inventory in combination with direct video observation using a novel structured task. We also analyzed how mothers¿ religiosity along several major dimensions related to their communication behaviors within both methods. Mothers (N = 39, M age = 40) of children aged 3-12 completed a survey packet on M-C spiritual discourse and standard measures of mothers¿ religious fundamentalism, intrinsic religiosity, sanctification of parenting (how much the mother saw herself as doing God¿s work as a parent), and a new measure of parental openness to children¿s spirituality. Then, in a structured task in our lab, mothers (N = 33) and children (M age = 7.33) watched a short film or read a short book that explored death in an age-appropriate manner and then engaged in a videotaped conversation about the movie or book and their religious or spiritual beliefs. Frequency of M-C spiritual discourse was positively related to mothers¿ religious fundamentalism (r = .71, p = .00), intrinsic religiosity (r = .77, p = .00), and sanctification of parenting (r = .79, p = .00), but, surprisingly, was inversely related to mothers¿ v openness to child¿s spirituality (r = -.52, p = .00). Survey data showed that the two most common topics discussed were God (once a week) and religion as it relates to moral issues (once a week). According to mothers their children¿s most common method of initiating spiritual discourse was to repeat what he or she has heard parents or family say about religious issues (M = 2.97; once a week); mothers¿ most common method was to describe their own religious/spiritual beliefs (M = 2.92). Spiritual discourse most commonly occurred either at bedtime or mealtime as reported by 26% of mothers, with the most common triggers reported as daily routine/random thoughts (once a week) and observations of nature (once a week). Mothers¿ most important goals for spiritual discourse were to let their children know that they love them (M = 3.72; very important) and to help them become a good and moral person (M = 3.67; very important). A regression model showed that significant variance in frequency of mother-child spiritual discourse (R2 = .84, p = .00) was predicted by the mothers¿ importance of goals during discourse (ß = 0.46, p = .00), frequency that the mother¿s spirituality was deepened through spiritual discourse (ß = 0.39, p = .00), and the mother¿s fundamentalism (ß = 0.20, p = .05). In a separate regression, the mother¿s comfort in the structured task (ß = 0.70, p = .00), and the number of open-ended questions she asked (ß = -0.26, p = .03) predicted the reciprocity between mother and child (R2 = .62, p = .00). In addition, the mother¿s age (ß = 0.22, p = .059) and comfort during the task (ß = 0.73, p = .00) predicted the child¿s engagement within the structured task. Other findings and theoretical and methodological implications will be discussed.
Comparative Analysis of Russian and French Prosodies: Theoretical, Experimental and Applied Aspects"
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Experience shows that in teaching the pronunciation of a foreign language, it is the native syllable stereotype that resists correction most strongly. This is because the syllable is the basic unit of the perception and production of speech, and syllabic production is highly automatic and to some degree determines the prosody of speech at all levels: accent, rhythm, phrase, etc. The results of psycho-physiological studies show that the human acoustic analyser is a typical contemplator organ and new acoustic qualities are perceived through their inclusion into the already existing system of values characteristic to the mother tongue. This results in the adaptation of the perception and so production of foreign speech to native patterns. The less conscious the perception of the unit and the more 'primitive' its status, the greater the degree of its auditory assimilation, and the syllable is certainly among the less controllable linguistic units. The group carried out a complex investigation of the French and Russian languages at the level of syllable realisation, focusing on the stressed syllable of both open and closed types. The useful acoustic characteristics of the French/Russian syllable pattern were determined through identifying a typical syllable pattern within the system of each of the two languages, comparing these patterns to establish their contrasting features, and observing and systematising deviations from the pattern typical of the French/Russian language teaching situation. The components of the syllable pattern shown to need particular attention in teaching French pronunciation to Russian native speakers were intensity, fundamental frequency, and duration. The group then developed a method of correction which combines the auditory and visual canals of sound signal perception and tested this method with groups of Russian students of different levels.
The nitrodibenzofuran chromophore: a new caging group for ultra-efficient photolysis in living cells
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Photochemical uncaging of bio-active molecules was introduced in 1977, but since then, there has been no substantial improvement in the properties of generic caging chromophores. We have developed a new chromophore, nitrodibenzofuran (NDBF) for ultra-efficient uncaging of second messengers inside cells. Photolysis of a NDBF derivative of EGTA (caged calcium) is about 16-160 times more efficient than photolysis of the most widely used caged compounds (the quantum yield of photolysis is 0.7 and the extinction coefficient is 18,400 M(-1) cm(-1)). Ultraviolet (UV)-laser photolysis of NDBF-EGTA:Ca(2+) rapidly released Ca(2+) (rate of 20,000 s(-1)) and initiated contraction of skinned guinea pig cardiac muscle. NDBF-EGTA has a two-photon cross-section of approximately 0.6 GM and two-photon photolysis induced localized Ca(2+)-induced Ca(2+) release from the sarcoplasmic recticulum of intact cardiac myocytes. Thus, the NDBF chromophore has great promise as a generic and photochemically efficient protecting group for both one- and two-photon uncaging in living cells.
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PURPOSE: The value of adjuvant tamoxifen after chemotherapy for premenopausal women with breast cancer has not been adequately assessed. PATIENTS AND METHODS: Between 1993 and 1999, International Breast Cancer Study Group Trial 13-93 enrolled 1,246 assessable premenopausal women with axillary node-positive, operable breast cancer. All patients received chemotherapy (cyclophosphamide plus either doxorubicin or epirubicin for four courses followed by immediate or delayed classical cyclophosphamide, methotrexate, and fluorouracil for three courses), which was followed by either tamoxifen (20 mg daily) for 5 years or no further treatment. The primary end point was disease-free survival (DFS). Tumors were classified as estrogen receptor (ER) -positive (n = 735, 59%) if immunohistochemical (IHC) or ligand-binding assays (LBA) were clearly positive. The ER-negative group included all other tumors (n = 511, 41%). A subset of the ER-negative group was defined as ER absent (n = 108, 9%) if IHC staining was none or if the LBA result was 0 fmol/mg cytosol protein. The median follow-up time was 7 years. RESULTS: Tamoxifen improved DFS in the ER-positive cohort (hazard ratio [HR] for tamoxifen v no tamoxifen = 0.59; 95% CI, 0.46 to 0.75; P < .0001) but not in the ER-negative cohort (HR = 1.02; 95% CI, 0.77 to 1.35; P = .89). Tamoxifen had a detrimental effect on patients with ER-absent tumors compared with no tamoxifen in an unplanned exploratory analysis (HR = 2.10; 95% CI, 1.03 to 4.29; P = .04). Patients with ER-positive tumors who achieved chemotherapy-induced amenorrhea had a significantly improved outcome (HR for amenorrhea v no amenorrhea = 0.61; 95% CI, 0.44 to 0.86; P = .004), whether or not they received tamoxifen. CONCLUSION: Tamoxifen after adjuvant chemotherapy significantly improved treatment outcome in premenopausal patients with endocrine-responsive disease, but its use as adjuvant therapy for patients with ER-negative tumors is not recommended.
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PURPOSE: To compare adjuvant dose-intensive epirubicin and cyclophosphamide chemotherapy administered with filgrastim and progenitor cell support (DI-EC) with standard-dose anthracycline-based chemotherapy (SD-CT) for patients with early-stage breast cancer and a high risk of relapse, defined as stage II disease with 10 or more positive axillary nodes; or an estrogen receptor-negative or stage III tumor with five or more positive axillary nodes. PATIENTS AND METHODS: Three hundred forty-four patients were randomized after surgery to receive seven cycles of SD-CT over 22 weeks, or three cycles of DI-EC (epirubicin 200 mg/m2 plus cyclophosphamide 4 gm/m2 with filgrastim and progenitor cell support) over 6 weeks. All patients were assigned tamoxifen at the completion of chemotherapy. The primary end point was disease-free survival (DFS). RESULTS: After a median follow-up of 5.8 years (range, 3 to 8.4 years), 188 DFS events had occurred (DI-EC, 86 events; SD-CT, 102 events). The 5-year DFS was 52% for DI-EC and 43% for SD-CT, with hazard ratio of DI-EC compared with SD-CT of 0.77 (95% CI, 0.58 to 1.02; P = .07). The 5-year overall survival was 70% for DI-EC and 61% for SD-CT, with a hazard ratio of 0.79 (95% CI, 0.56 to 1.11; P = .17). There were eight cases (5%) of anthracycline-induced cardiomyopathy (two fatal) among those who received DI-EC. Women with hormone receptor-positive tumors benefited significantly from DI-EC. CONCLUSION: There was a trend in favor of DI-EC with respect to disease-free survival. A larger trial or meta-analysis will be required to reveal the true effect of dose-intensive therapy.
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BACKGROUND: We sought to determine whether a high-risk group could be defined among patients with operable breast cancer in whom a search of occult central nervous system (CNS) metastases was justified. PATIENTS AND METHODS: We evaluated data from 9524 women with early breast cancer (42% node-negative) who were randomized in International Breast Cancer Study Group clinical trials between 1978 and 1999, and treated without anthracyclines, taxanes, or trastuzumab. We identified patients whose site of first event was CNS and those who had a CNS event at any time. RESULTS: Median follow-up was 13 years. The 10-year incidence (10-yr) of CNS relapse was 5.2% (1.3% as first recurrence). Factors predictive of CNS as first recurrence included: node-positive disease (10-yr = 2.2% for > 3 N+), estrogen receptor-negative (2.3%), tumor size > 2 cm (1.7%), tumor grade 3 (2.0%), < 35 years old (2.2%), HER2-positive (2.7%), and estrogen receptor-negative and node-positive (2.6%). The risk of subsequent CNS recurrence was elevated in patients experiencing lung metastases (10-yr = 16.4%). CONCLUSION: Based on this large cohort we were able to define risk factors for CNS metastases, but could not define a group at sufficient risk to justify routine screening for occult CNS metastases.
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BACKGROUND: Others have reported ocular toxicity after adjuvant chemoendocrine therapy, but this study looked at ocular toxicity in similarly treated patients from large randomized clinical trials. METHODS: Information was retrieved on incidence and timing of ocular toxicity from the International Breast Cancer Study Group (IBCSG) database of 4948 eligible patients randomized to receive tamoxifen or toremifene alone or in combination with chemotherapy (either concurrently or sequentially). Case reports of patients with ocular toxicity were evaluated to determine whether ocular toxicity occurred during chemotherapy and/or hormonal therapy. Additional information was obtained from participating institutions for patients in whom ocular toxicity occurred after chemotherapy but during administration of tamoxifen or toremifene. RESULTS: Ocular toxicity was reported in 538 of 4948 (10.9%) patients during adjuvant treatment, mainly during chemotherapy. Forty-five of 4948 (0.9%) patients had ocular toxicity during hormone therapy alone, but only 30 (0.6%) patients had ocular toxicity reported either without receiving any chemotherapy or beyond 3 months after completing chemotherapy and, thus, possibly related to tamoxifen or toremifene. In 3 cases, retinal alterations, without typical aspects of tamoxifen toxicity, were reported; 4 patients had cataract (2 bilateral), 12 impaired visual acuity, 10 ocular irritation, 1 optical neuritis, and the rest had other symptoms. CONCLUSION: Ocular toxicity during adjuvant therapy is a common side effect mainly represented by irritative symptoms due to chemotherapy. By contrast, ocular toxicity during hormonal therapy is rare and does not appear to justify a regular program of ocular examination. However, patients should be informed of this rare side effect so that they may seek prompt ophthalmic evaluation for ocular complaints.