Bjørn Ove Mæhle

The formalin test in mice : effect of formalin concentration

&NA; The effect of different formalin concentrations on the nociceptive response in the formalin test was examined in mice. Subcutaneous formalin injection induces 2 distinct periods of high licking activity: an early phase lasting the first 5 min, and a late phase lasting 20–30 min after the injection. Formalin concentrations of 0.02–0.2% induced only the early phase, while concentrations of 1% or more induced both the early phase and the late phase. The ability of the test to show the antinociceptive effect of morphine and acetylsalicylic acid was similar for high and low formalin concentrations. For both these analgesics, a lower dose was needed to induce antinociception in the late phase than in the early phase using the same formalin concentration. Indomethacin had no effect in the early phase. In the late phase indomethacin induced antinociception when 1% formalin was used, while no significant effect was observed using 5% formalin. Clear histological changes in the paw were demonstrated after formalin concentrations that induced both phases. Lower formalin concentrations induced only very small changes. Using a low formalin concentration (0.2%), repeated testing using the same paw could be performed at intervals of 1 week without any significant change in the response. It was concluded that the formalin concentration should be kept as low as possible to minimize the suffering of the animal. Formalin concentrations of 0.05‐0.2% are recommended for studying the early phase. Formalin concentrations of 1% or higher have to be used when studying the nociceptive response in the late phase.

Birth weight as a predictor of breast cancer: a case–control study in Norway

The hypothesis that birth weight is positively associated with adult risk of breast cancer implies that factors related to intrauterine growth may be important for the development of this malignancy. Using stored birth records from the two main hospitals in Trondheim and Bergen, Norway, we collected information on birth weight, birth length and placenta weight among 373 women who developed breast cancer. From the same archives, we selected as controls 1150 women of identical age as the cases without a history of breast cancer. Information on age at first birth and parity were collected from the Central Person Registry in Norway. Based on conditional logistic regression analysis, breast cancer risk was positively associated with birth weight and with birth length (P for trend=0.02). Birth weights in the highest quartile (3730 g or more) were associated with 40% higher risk (odds ratio, 1.4, 95% confidence interval, 1.1–1.9) of breast cancer compared to birth weights in the lowest quartile (less than 3090 g). For birth length, the odds ratio for women who were 51.5 cm or more (highest quartile) was 1.3 (95% confidence interval, 1.0–1.8) compared to being less than 50 cm (lowest quartile) at birth. Adjustment for age at first birth and parity did not change these estimates. Placenta weight was not associated with breast cancer risk. This study provides strong evidence that intrauterine factors may influence future risk of breast cancer. A common feature of such factors would be their ability to stimulate foetal growth and, simultaneously, to influence intrauterine development of the mammary gland.

Pre-morbid body-mass-index in breast cancer: Reversed effect on survival in hormone receptor negative patients

SummaryThe present study consists of 1,238 women with unilateral breast cancer treated with modified radical mastectomy living in the geographic area of Haukeland Hospital. Their weight and height had been measured years before presentation of the disease. Age-adjusted Quetelets index (weight/height2) showed that obese women had a 49% higher risk of dying from breast cancer than lean ones. The relative risk decreased slightly when adjusted for tumour diameter, lymph node status, and mean nuclear area of the tumour cells. The prognostic effect of Quetelets index was examined according to the estrogen and/or progesterone receptor status of the tumour. In patients with a hormone receptor positive tumour, obese women had a risk that was more than three times higher than lean ones. In patients with hormone receptor negative tumour, the effect of obesity was reversed, lean patients having a risk that was more than six times higher than obese ones, even after adjustment for lymph node status, tumour diameter, and mean nuclear area. Quetelets index, while being a prognostic variable in its own right, thus acts differently in patients with hormone receptor positive and negative tumours.

Premorbid body weight and its relations to primary tumour diameter in breast cancer patients; its dependence on estrogen and progesteron receptor status

Hormonal mechanisms have been offered as an explanation for the higher frequency of large tumours, lymph node metastases and poorer prognosis in obese breast cancer patients than in lean ones. If hormonal mechanisms are important for these relations, they should probably act more strongly in patients with hormonal receptor positive tumours than in those with negative ones. We have examined if the relations between premorbid body weight or Quetelets index (weight/height2) and tumour diameter are modified by estrogen receptor alpha (ER) and progesteron receptor (PgR) status. The analyses were based on 1,241 women with unilateral disease treated with modified radical mastectomy living in the geografic area of Haukeland Hospital. Their body weight and height have been measured as a mean 12.5years before presentation of the disease. Body weight and Quetelets index have been adjusted for age. The relations were studied using linear regression analyses adjusting the effect of body weight with height and mean nuclear area of the tumour cells and adjusting the effect of Quetelets index for mean nuclear area. The main findings showed that patients with high body weight or Quetelets index presented more often with PgR positive tumours than lean ones. Quetelets index was also positively related to ER. These relations were present in patients older than 50 years of age (older). Patients with large tumours (>2.0cm) had significantly higher body weight and Quetelets index than those with small ones. These differences were significantly present in older patients and in patients with PgR negative and ER negative – PgR negative tumours. Linear regression analyses confirmed that tumour diameter increases with body weight and Quetelets index. These relations were present in both lymph node groups and in older patients. Stratification according to hormonal receptor status showed these relations to be significant in patients with ER negative, with PgR negative and those with ER negative – PgR negative tumours only. Taking age and hormonal receptor status into consideration simultaneously, both body weight and Quetelets index were significantly related to tumour diameter in older patients with hormone receptor negative tumours. In conclusion body size was positively related to hormone receptor status and to diameter of the primary tumour. The relation to tumour diameter was present in older patients with hormone receptor negative tumours. Although hormonal mechanisms able to act on the tumour can not be excluded, mechanisms acting independent of hormonal receptors must be considered. Different mechanisms related to body fat cytokines are discussed.

Mean nuclear area and histological grade of axillary-node tumour in breast cancer, related to prognosis

In a series of 112 cases of breast carcinoma with metastases to the axillary nodes, the mean nuclear area (MNA) in the nodal tumour showed a relationship to survival time that was similar to that given by histological grading. Combination of the 2 measurements increases the possible use of the heterogeneity of the material, leading to a more individualized prognosis.

Negative selection of human monocytes using magnetic particles covered by anti-lymphocyte antibodies

We have developed a standardized procedure for the isolation of monocytes from peripheral blood by negative selection using magnetic polymer particles coated with monoclonal antibodies against T and B lymphocytes. The average purity of the monocyte suspension was 85%, and monocyte recovery was 72% from Ficoll-Hypaque gradient separated mononuclear cells and 32% from whole blood. In a lucigenin enhanced chemiluminescence assay there was no significant difference between cells separated immunomagnetically and those separated on a gradient. Nor did electron microscopy show any significant difference in morphology between such monocytes. Negative selection using magnetic polymer particles is an efficient method for the separation of monocytes with intact morphology and function as measured by chemiluminescence.

The associations of obesity, lymph node status and prognosis in breast cancer patients: Dependence on estrogen and progesterone receptor status

Breast cancer patients who are obese have a higher risk of lymph node metastases and a poorer prognosis than those who are slim. It has been claimed that estrogens derived from fat are important for these associations. If estrogens are important, these relationships must be stronger in the hormone receptor‐positive than in the hormone receptor‐negative groups. Body mass index (BMI) was used as a measure of obesity. The second, third, and fourth quintiles of BMI were treated as one group and termed ‘medium’. Patients in the fifth quintile were termed ‘obese’ and those in the first quintile ‘slim’. The number of women with unilateral disease treated with modified radical mastectomy and included in the study was 1211. Of all patients included, obese patients had a 1.53 higher risk of lymph node metastases compared to slim patients (p=0.02). In the PgR‐negative group, obesity gave a 3.08 times higher risk of lymph node metastases (p=0.03). The risk of dying of breast cancer tended to be higher in obese than in slim patients when all patients in the study were compared (relative risk=1.38, p=0.06). BMI did not show a statistically significant relationship with prognosis if only hormone receptor status was considered. However, if lymph node status and hormone receptor status were taken together, the association was strong and reversed in the lymph node‐positive group with ER‐negative tumours. The adjusted relative risk was 0.33, showing that slim patients had a 3.03 (1.0/0.33) times higher risk of dying of breast cancer compared to obese patients (p=0.002). These results indicate that non‐hormonal mechanisms could be important.

Prognostic role of oestrogen and progesterone receptors in patients with breast cancer: relation to age and lymph node status.

AIMS: To consider the prognostic role of oestrogen receptor and progesterone receptor status in relation to the age at surgery, length of follow up and lymph node status. METHODS: The study population comprised 977 patients with histologically confirmed breast carcinoma, with a median follow up of nine years. The actuarial life table method was used to test for survival differences. The Cox proportional hazard model was used to test for interaction effects between each hormone receptor and age, lymph node status and length of follow up. As the analysis involved multiple subgroups, significance was set at the 1% level (p < 0.01). RESULTS: When the patients were subdivided into groups according to lymph node status and age, progesterone and oestrogen receptor status predicted prognosis in middle aged (46-60 years) patients with lymph node positive breast cancer. Their prognostic effect in this subgroup, however, was restricted to the first five years after surgery. Progesterone receptor status was the strongest predictor of outcome. CONCLUSION: The prognostic power of oestrogen and progesterone receptor status varies depending on age, lymph node status and length of follow up after surgery.

The prognostic contribution of estrogen and progesterone receptor status to a modified version of the Nottingham Prognostic Index

The aim of this study was to test the prognostic contribution of estrogen (ER) and progesterone (PgR) receptor status to an index consisting of the number of positive lymph nodes, the mean nuclear area of the breast cancer cells (MNA), and tumour diameter. This index is compared with a Danish index, which includes the same factors but uses histological grade instead of MNA. The Danish index has been developed from the Nottingham Prognostic Index (NPI). In the present study of 1629 breast cancer patients the Cox proportional hazard method is used to examine the time-dependency of the index, and to test for interaction between the index and the hormone receptors. The index sorts the patients into groups with low, intermediate, and high risk of dying. Logistic regression analysis is used to report the sensitivity and specificity of the index with and without ER and PgR. Our index gave information comparable to that of the Danish group. However, the information given by our index is time-dependent, its strength being weaker after 5-year of follow-up. PgR and ER add information to high risk patients, but only in the first 5-year period. High risk patients with positive hormone receptors have a prognosis similar to intermediate risk ones. PgR increases the ability of the index to predict breast cancer deaths correctly by 5 percent in high risk patients. In conclusion, PgR and ER act differently in groups of patients with different risk levels when time-dependency is considered. This indicates biological differences in subgroups as defined by the index.

Large intramuscular spindle-cell lipoma

A case of a large spindle‐cell lipoma in an intramuscular (subfascial) localization is reported. The tumour occurred in a 58‐year‐old male patient and was localized subfascially in his left deltoid muscle. The tumour measured 20 × 8 × 8 cm; its weight was 780 grams. After initial biopsy, the tumour was extirpated. Microscopically, the tumour tissue consisted of mature fat cells and spindle‐cell areas in varying amounts, constituting a typical appearance of a spindle‐cell lipoma. There were no histological signs of malignancy. Especially, no areas of liposarcoma differentiation were detected. The patient is well, with no signs of recurrence, one and a half years after the operation. We have reviewed the literature on spindle‐cell lipoma, and we believe this is the first example of this neoplasm to be reported in an intramuscular (subfascial) localization.