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Biomedical subjects

D A Cameron

Publications and source records attributed to D A Cameron.

At least 19 recordsLinked to original sources
PubMed2006

The effects of chemotherapy and long-term gonadotrophin suppression on the ovarian reserve in premenopausal women with breast cancer.

BACKGROUND: Reproductive function following cancer treatment is of increasing importance with improving survival rates. We therefore assessed the markers of the ovarian reserve in premenopausal women, to investigate and compare the effects of chemotherapy and long-term gonadotrophin withdrawal on ovarian function. METHODS: Fifty premenopausal (age range 28-52 years) women with early breast cancer were recruited. Serum hormone and ovarian ultrasound measurements were taken before treatment and at intervals up to 1 year during chemotherapy or gonadotrophin suppressive therapy. RESULTS: Pretreatment samples indicated a fall in anti-Müllerian hormone (AMH) concentration with age before changes in other hormone concentrations. AMH concentration showed a rapid and marked fall during chemotherapy, with undetectable concentrations in many women (P<0.0001). Inhibin B concentration showed a lesser fall (P<0.0001), whereas estradiol (E2) concentrations were maintained. Both antral follicle count (AFC) and ovarian volume fell (P<0.0001 and P<0.05 respectively). Regimens containing taxanes in addition to cyclophosphamide showed increased gonadotoxicity. Gonadotrophin suppression resulted in expected falls in E2 (P<0.05) and inhibin B (P<0.001) levels, but also resulted in a delayed fall in AMH level after 6 months (P<0.0001). CONCLUSIONS: These data confirm the value of AMH concentration as an early indicator of ovarian ageing including assessment of chemotherapy-induced ovarian follicle loss. FSH and AMH concentration measurements may be useful for the comparison of ovarian toxicity of different chemotherapy regimens.

Adult↗
PubMed2006

EORTC guidelines for the use of granulocyte-colony stimulating factor to reduce the incidence of chemotherapy-induced febrile neutropenia in adult patients with lymphomas and solid tumours.

Chemotherapy-induced neutropenia is not only a major risk factor for infection-related morbidity and mortality, but is also a significant dose-limiting toxicity in cancer treatment. Patients developing severe (grade 3/4) or febrile neutropenia (FN) during chemotherapy frequently receive dose reductions and/or delays to their chemotherapy. This may impact on the success of treatment, particularly when treatment intent is either curative or to prolong survival. The incidence of severe or FN can be reduced by prophylactic treatment with granulocyte-colony stimulating factors (G-CSFs), such as filgrastim, lenograstim or pegfilgrastim. However, the use of G-CSF prophylactic treatment varies widely in clinical practice, both in the timing of therapy and in the patients to whom it is offered. While several academic groups have produced evidence-based clinical practice guidelines in an effort to standardise and optimise the management of FN, there remains a need for generally applicable, European-focused guidelines. To this end, we undertook a systematic literature review and formulated recommendations for the use of G-CSF in adult cancer patients at risk of chemotherapy-induced FN. We recommend that patient-related adverse risk factors such as elderly age (>or=65 years), be evaluated in the overall assessment of FN risk prior to administering each cycle of chemotherapy. In addition, when using a chemotherapy regimen associated with FN in >20% patients, prophylactic G-CSF is recommended. When using a chemotherapy regimen associated with FN in 10-20% patients, particular attention should be given to patient-related risk factors that may increase the overall risk of FN. In situations where dose-dense or dose-intense chemotherapy strategies have survival benefits, prophylactic G-CSF support is recommended. Similarly, if reductions in chemotherapy dose intensity or density are known to be associated with a poor prognosis, primary G-CSF prophylaxis may be used to maintain chemotherapy. Finally, studies have shown that filgrastim, lenograstim and pegfilgrastim have clinical efficacy and we recommend the use of any of these agents to prevent FN and FN-related complications, where indicated.

Antineoplastic Agents↗
PubMed2004

Anastrozole demonstrates clinical and biological effectiveness in oestrogen receptor-positive breast cancers, irrespective of the erbB2 status.

Overexpression of erbB2 in breast tumours can predict resistance to tamoxifen therapy. We conducted a small trial to determine if erbB2 status correlates with tumour response and biochemical changes in postmenopausal women receiving neoadjuvant therapy with the aromatase inhibitor, anastrozole. Twenty-four postmenopausal women with oestrogen receptor (ER)-rich, large, operable breast tumours received three months of neoadjuvant anastrozole, 1 or 10 mg daily, then surgery, followed by another five years of anastrozole 1 mg daily. Response to the treatment was based on changes in clinical and ultrasound measurements of tumour volume and changes in tumour proliferation and progesterone receptor (PgR) status. After follow-up for a median duration of four years therapy, there was no apparent difference between erbB2 0/1+ and erbB2 3+ tumours in clinical response or changes in proliferation and PgR expression. In conclusion, anastrozole appears to be an effective endocrine option in this patient population, irrespective of the erbB2 status.

Aged↗
PubMed2003

Moderate neutropenia with adjuvant CMF confers improved survival in early breast cancer.

Despite the extensive literature clearly demonstrating the survival benefit for adjuvant chemotherapy in women with operable breast cancer, there are few data confirming this in routine practice. Some studies have suggested that not all women gain to the same extent, with older women showing a smaller benefit and lower doses achieving poorer outcomes. We therefore reviewed the case notes of 750 women treated over a 15-year period at The Edinburgh Cancer Centre with the same intravenous CMF (cyclophosphamide, methotrexate and 5-fluorouracil) regimen, to identify patient- and treatment-related factors influencing outcome in routine practice. The actuarial 10-year survival for these women was 59.3%, with the anticipated poorer outcome for those with more involved ipsilateral axillary nodes, higher grade and ER-negative tumours. There was no evidence that a lower delivered dose intensity or older age at presentation resulted in a poorer survival. Of particular interest was the observation that 45% of patients who had grade 2/3 neutropenia had a 10% absolute survival advantage over those with no neutropenia (P<0.001). This strongly suggests that some degree of neutropenia has more influence on outcome than age or delivered dose intensity.

Adult↗
PubMed2003

Physical impairments related to kinetic energy during sit-to-stand and curb-climbing following stroke.

OBJECTIVE: Compare kinetic energy and duration of task during sit-to-stand and curb-climbing of two groups: hemiparetic stroke patients and matched controls. For patients, describe relationships between selected physical impairments and sit-to-stand and curb-climbing performance. DESIGN: Descriptive and correlational.Background. Measures and treatments are best selected after specific limitations in functional activities (e.g., sit-to-stand) and related impairments are identified. METHOD. Fifteen patients, 29-77 (mean=53.7) years with recent stroke and 15 demographically matched healthy controls participated. Physical performance variables measured were standing balance, maximum paretic extremity weight-bearing, and knee extension strength. Sit-to-stand and curb-climbing performance were characterized using kinetic energy and task duration. Differences in physical and functional performance between groups were determined. Spearman correlations were calculated between patients' physical impairments and sit-to-stand and curb-climbing performance. RESULTS: Compared to controls, patients demonstrated reduced kinetic energy (P< or =0.003) and prolonged duration (P< or = 0.001) for sit-to-stand and curb-climbing. Significant relationships (r(s)=0.49-0.50) were demonstrated between sit-to-stand kinetic energy and knee extension strength, standing balance, and maximum weight-bearing. For curb climbing, significant relationships (r(s)=0.45) were found between kinetic energy and standing balance and maximum weight-bearing. CONCLUSION: Impaired balance and maximum weight-bearing are relevant to sit-to-stand and curb-climbing limitations after stroke. RELEVANCE: Clinicians treating sit-to-stand or curb-climbing limitations have reason to measure and treat impairments in maximum weight-bearing, knee extension strength, and standing balance.

Activities of Daily Living↗
PubMed2002

Block sequential adriamycin CMF--optimal non-myeloablative chemotherapy for high risk adjuvant breast cancer?

After the publication of the 10-year survival data from Milan on the adjuvant use of the block sequential regimen consisting of four cycles of adriamycin followed by eight cycles of intravenous CMF, many centres adopted this as standard of care for high risk, multiple node-positive breast cancer. For this reason it was identified as the standard arm for the Anglo-Celtic adjuvant high-dose chemotherapy trial. This study reports on the experience of this regimen in 329 women with early breast cancer involving at least four axillary nodes, who were treated outside any adjuvant chemotherapy trial. At a median follow-up of 3 years, the overall 5-year disease-free survival is 61%, and the overall survival is 70%. These data confirm the efficacy of this regimen in non-trial patients, and, for the same high risk subgroup, indicate that this approach offers an outcome at least as good as that seen in the CALGB 9344 AC-Taxol arm, and the NCIC days 1 and 8 CEF.

Adult↗
PubMed2001

A visual pigment expressed in both rod and cone photoreceptors.

Rods and cones contain closely related but distinct G protein-coupled receptors, opsins, which have diverged to meet the differing requirements of night and day vision. Here, we provide evidence for an exception to that rule. Results from immunohistochemistry, spectrophotometry, and single-cell RT-PCR demonstrate that, in the tiger salamander, the green rods and blue-sensitive cones contain the same opsin. In contrast, the two cells express distinct G protein transducin alpha subunits: rod alpha transducin in green rods and cone alpha transducin in blue-sensitive cones. The different transducins do not appear to markedly affect photon sensitivity or response kinetics in the green rod and blue-sensitive cone. This suggests that neither the cell topology or the transducin is sufficient to differentiate the rod and the cone response.

Ambystoma↗
PubMed2001

Adjuvant interferon alpha 2b in high risk melanoma - the Scottish study.

In 1989, the Scottish melanoma group initiated a randomized trial, comparing observation alone with 6 months' therapy with low dose interferon (given subcutaneously 3 MU day-1, twice weekly), for patients with primary melanomas of at least 3 mm Breslow thickness, or with evidence of regional node involvement. The trial was closed in 1993 with only 95 eligible patients randomized. There were no toxic deaths, and no patient failed to complete the treatment for reasons of toxicity. 6 months' treatment with low-dose interferon- resulted in a statistically significant improved disease-free survival for up to 24 months after randomization (P< 0.05). However, at a median follow-up of over 6 years, although there was an apparent improvement in disease-free survival (from 9 to 22 months), and overall survival (from 27 to 39 months), consistent with larger studies powered to detect such differences, these differences were not statistically significant. The data therefore suggest that 6 months of low-dose interferon is active, and confirm the importance of the large randomized studies, such as the UKCCCR AIM-High and EORTC trials, that seek to confirm a possible survival advantage for low or intermediate dose interferon.

Adult↗
PubMed2001

Evidence for two distinct mechanisms of neurogenesis and cellular pattern formation in regenerated goldfish retinas.

After its destruction by intraocular injection of ouabain, the goldfish retina regenerates, but little is known about the histogenesis of the new tissue, including the structure and formation of regenerated cell mosaic patterns. In an effort to determine how retinal cells are generated and spatially organized within retina regenerated after ouabain injection, in situ hybridization and immunocytochemical techniques were combined with computational analyses of two-dimensional spatial patterns of identified neurons. Labeling with specific opsin riboprobes revealed two distinct cone patterns in the ouabain-injected eyes, each of which was different from the relatively orderly cone patterns of native retina. Central, regenerated regions had sparse aggregates of cones, and a relatively lower density of each cone type. Peripheral regions of experimental retina, likely derived from the circumferential germinal zone, had high densities of all cone types, each of which tended to be distributed randomly. The spatial patterns of inner retinal neurons in experimental eyes were also disorganized with respect to native retina. These results indicate that although some aspects of retinal regeneration resemble normal retinal development and growth, ouabain-induced regeneration does not produce well-organized mosaics of neurons, indicating a failure of the developmental interactions needed for proper pattern formation, which in turn could compromise visual recovery. Furthermore, the distinct cone patterns in different regions of experimental retina support the hypothesis that new goldfish retina arises via two spatially and cellularly distinct mechanisms after exposure to ouabain.

Animals↗
PubMed2001

The relative importance of proliferation and cell death in breast cancer growth and response to tamoxifen.

Changes in tumour volume depend on the relative balance between cell proliferation and cell loss. However, these processes are not independent, and it remains unclear which is more important in tumour progression and regression. For example, the anti-oestrogen tamoxifen, a mainstay in the therapy of breast cancer, has both antiproliferative and pro-apoptotic actions, and their relative importance in clinical efficacy is unknown. Thus, using a model system based on oestrogen receptor (ER)-positive ZR-75-1 breast cancer xenografts, both increased apoptosis and reduced proliferation have been previously shown to occur within 7 days of tamoxifen therapy (Cameron DA, Ritchie AA, Langdon S, Anderson TJ, Miller WR. Tamoxifen induced apoptosis in ZR-75 breast cancer xenografts antedates tumour regression. Breast Cancer Res Treat 1997, 45, 99--107). In the present study, Gompertzian growth curves have been fitted to individual breast cancer xenografts. This demonstrates that the growth rate of the untreated tumours is directly dependent only on the mitotic rate (P<0.001), whereas tumour response to tamoxifen correlates most strongly (P< 0.001) with the relative balance between apoptosis and mitosis, as evidenced by the apoptotic:mitotic ratio.

Animals↗
PubMed2001

Biological and clinical effects of aromatase inhibitors in neoadjuvant therapy.

Postmenopausal women with large primary oestrogen receptor-rich (>20 fmol/mg protein or 80 histoscore) breast cancers have been treated neoadjuvantly with either letrozole (2.5 or 10 mg daily n=12 in each case) or anastrozole (1 or 10mg daily n=12 and 11, respectively). Tumour was available for analysis before treatment (wedge biopsy) and 3 months later at definitive surgery (wide local excision or mastectomy). Clinical response to treatment was assessed by sequential measurements of tumour volume based on caliper assessment, ultrasound and mammography. Results showed that in these selected groups of patients a reduction in tumour volume with treatment was observed in 43 of 47 cases (91%). Pathological responses, i.e. clear decrease in tumour cellularity or increased fibrosis was evident in 32 cases (68%). Furthermore, there was a decrease with therapy in immunohistochemical staining for Ki67 in all tumours. Staining for progesterone receptor (PgR) was reduced in all 21 PgR-positive cancers treated with letrozole and in 16 of 17 positive cancers treated with anastrozole. These effects are at least as great as those seen in a non-randomised group of patients treated with tamoxifen over the same time period (additionally tamoxifen treatment was often associated with an increase in PgR staining). The results suggest that potent specific aromatase inhibitors will be valuable in treating hormone-dependent cancers.

Anastrozole↗
PubMed2001

Letrozole as primary medical therapy for locally advanced and large operable breast cancer.

AIMS: To investigate the efficacy of letrozole 2.5 mg and 10 mg used as primary neoadjuvant therapy for patients with locally advanced and large operable breast cancer. PATIENTS AND METHODS: Twenty-four postmenopausal patients with locally advanced or large operable breast cancer were treated in two consecutive series with letrozole 2.5 mg (n = 12) or letrozole 10 mg (n = 12). Response at three months was measured by change in tumor volume according to WHO criteria (partial response was defined as a reduction in tumor volume > or = 65%). Tumor volumes were assessed clinically, by ultrasound and mammography, and pathologically. RESULTS: All 24 patients were estrogen receptor-positive, were considered 'receptor-rich', and mean age was 77.6 years and 71.6 years in the letrozole 2.5 mg and 10 mg treatment groups, respectively. There were five complete clinical responses and seven partial clinical responses in the patients treated with 2.5 mg letrozole, and nine partial responses and three patients with stable disease in patients treated with 10 mg letrozole. Assessed by ultrasound and mammography, the 12 patients treated with 2.5 mg had one complete response, nine partial responses and two with no change. In the 12 patients treated with 10 mg letrozole, imaging gave eight partial responses and four with no change. One patient treated with the 2.5 mg dose had a complete clinical and pathological response. There was no significant difference between the two doses in effect on tumor volume, and no recordable side effects associated with either dose. CONCLUSION: Letrozole used in a neoadjuvant setting is highly effective, producing clinically beneficial reductions in tumor volume allowing all patients to have breast conserving surgery, and has an acceptable safety profile.

Aged↗
PubMed2001

Intraoperative study of polarization and evoked response signals in different endocardial electrode designs.

Some new generation pacemakers use an algorithm based on evoked response (ER) detection to verify beat-to-beat capture and to enable automatic adjustment of output. This is a prospective acute study of polarization signal (PS) and ER in nine currently available electrodes. Intraoperative testing of ventricular bipolar electrodes used the Autocapture (AC) algorithm. The intrinsic R wave, PS, ER, acceptance of AC function, and stimulation thresholds (STs) were obtained. Ventricular electrodes were categorized as follows: titanium nitride (TiN)-coated passive and active fixation, high impedance (HI), passive fixation (VP), iridium oxide-coated titanium (IROX) (VI), and platinum helix (PH) active fixation. Acute testing was performed in 217 patients with an average age of 74.26 years, 59.6% were men with primary pacing indication-SSS (46.3%). There were no significant differences found with respect to R wave and threshold between the various electrodes. PH active-fixation electrodes had significantly higher ER and PS than other groups including the TiN-coated active-fixation electrodes. TiN-coated electrodes (active and passive fixation) had significantly lower PS than other electrodes. As a result, TiN electrodes had a significantly higher functional rate of AC (91.7%), whereas PH had the lowest rate (0%). In conclusion, (1) polarization characteristics are significantly different for commercially available ventricular electrodes, (2) certain physical features at the tissue to electrode interface like TiN coating appears to be more important in determining PS than electrode tip size and fixation method, and (3) the current algorithm for AC requires electrodes that provide low polarization for satisfactory performance.

Adult↗
PubMed2001

Snoring, sleep apnoea and the role of dental appliances.

This article describes the problems of snoring and obstructive sleep apnoea, together with an outline of treatment options. The Glasgow approach, whereby patients are investigated at a sleep clinic and a custom-made mandibular advancement device is made in semi-soft material, is also described. We have demonstrated the acceptability and effectiveness of a simple appliance in patients with varying dental states, some with simple snoring and some with mild to moderate sleep apnoea. Our experience relates to around 260 patients, extending over a period of 4 years with good success. The simple intraoral device is recommended as a first line of approach for patients with problem snoring.

Equipment Design↗
PubMed2000

Cell mosaic patterns in the native and regenerated inner retina of zebrafish: implications for retinal assembly.

In part because of its laminar organization and morphologically distinct cell populations, the vertebrate retina has often been used as a system for investigating the assembly of neural structures. The retinas of adult teleost fish, because they grow throughout life and can regenerate following an injury, provide an especially attractive model system for such investigations. In an effort to provide a quantitative foundation for testing hypotheses regarding the mechanisms of pattern formation during growth and regeneration of the vertebrate retina, nearest neighbor and auto-correlation analyses were used to examine the mosaic patterns of eight inner retinal cell groups in the native and regenerated retina of adult zebrafish. In both native and regenerated retina, the mosaic patterns of most inner retinal cells are non-random. However, regenerated mosaics tend toward significantly lower nearest neighbor distances, less orderly patterns, and more variable radial locations than their native retina counterparts. The individual cell groups in both native and regenerated inner retina are likely to be spatially distributed independently. The results support the hypotheses that, in the adult zebrafish: 1) distinct inner retinal cell groups of native retina are also present in regenerated retina; 2) the assembly of inner retinal cell mosaics is controlled by non-random spatial organizing mechanisms during development, growth, and regeneration; and 3) the spatial organization of cell mosaics is disrupted during regeneration. The results suggest that retinal regeneration may represent a spatially disrupted recapitulation of retinal developmental mechanisms.

Animals↗
PubMed2000

Effective tamoxifen therapy of breast cancer involves both antiproliferative and pro-apoptotic changes.

Despite knowledge of oestrogen receptor status, it is not always possible to predict which breast cancers will respond to tamoxifen. We have previously reported that decreased expression of Bcl-2 and/or Ki-S1 were associated with tumour response to neo-adjuvant tamoxifen in 50 elderly women with oestrogen receptor (ER)-positive breast cancer. In this study, we confirm that the expression of Bcl-2 and Ki-S1 are surrogates for the frequency of apoptosis and mitosis respectively, within these untreated breast cancers, with an inverse relationship between Bcl-2 expression and the apoptotic index (P<0.05), and a positive relationship between Ki-S1 expression and the mitotic index (P<0.01). However, after 3 months' tamoxifen treatment these relationships were no longer apparent. Moreover, amongst the 27 tumours in which Bcl-2 expression was reduced during the 3 months' therapy, there was a significant correlation between the response to therapy and the increase in apoptosis (P<0.05), whereas in those tumours in which Bcl-2 did not fall with therapy, there was a significant correlation between response and the decrease in mitosis (P<0.05). These data suggest there are at least two mechanisms for effective tamoxifen therapy: increased apoptosis as a consequence of reduced Bcl-2 expression, and decreased proliferation.

Aged↗