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Biomedical subjects

C May

Publications and source records attributed to C May.

At least 145 records · Page 8Linked to original sources
PubMed1984

Bilateral breast cancer in northern Alberta: risk factors and survival patterns.

Of 2231 women with stage I, II or III breast cancer who were registered and seen between 1971 and 1979 and followed to the end of 1981, 48 (2.2%) had synchronous and 58 (2.6%) asynchronous bilateral breast cancer. The unadjusted incidence rate for a second breast cancer was 6.4/1000 breast-years at risk, compared with a rate of 0.70 for the risk of a first breast cancer in women. When calculated from the date of diagnosis of the first breast cancer the survival rate was better for the group with asynchronous disease than for the group with synchronous disease or for a group with unilateral disease, but when calculated from the date of diagnosis of the second cancer the rate was the same in all three groups. Comparison of known risk factors showed a significant association between the development of bilateral cancer and a later age at the birth of the first child and a longer interval between menarche and that birth. There was a trend towards greater age and more stage III cancer in the group with synchronous disease. There was no correlation between receiving radiotherapy for the first breast cancer and development of the second cancer. Annual mammography and clinical examination of asymptomatic women at a cancer centre resulted in the detection of a significantly higher proportion of minimal breast cancers in the second breast compared with the first. Such screening practices should be even more valuable in the earlier detection of unilateral breast cancer in asymptomatic women who have not had breast cancer.

Actuarial Analysis↗
PubMed1982

Comparison of glycohemoglobin determination and the one-hour oral glucose screen in the identification of gestational diabetes.

A prospective study was undertaken to evaluate the use of glycohemoglobin (HbA1) as a screening tool for the detection of gestational diabetes in 90 subjects. At 28 to 30 weeks, these patients had an HbA, determination prior to diabetes screening with a 1-hour serum glucose after 50 gm of oral glucose. Those women with an abnormal screening result were then evaluated with a standard 3-hour oral glucose tolerance test. Forty-seven women had an abnormal 1-hour serum glucose (greater than or equal to 140 mg/dl). Nine of these 47 women (19%) had an abnormal HbA1. Four of these nine women (44.4%) with an abnormal screening glucose as well as an abnormal HbA1 demonstrated an abnormal oral glucose tolerance test. Eleven of 38 women (29%) with an abnormal glucose screen but normal HbA1 had an abnormal glucose tolerance test. The combination of two abnormal tests, glucose screen and HbA1, predicted gestational diabetes in only four of 15 (27%) of our patients. The sensitivity and specificity of this combination were 22.4% and 87.8%, respectively. The median values of HbA, with normal and abnormal glucose tolerance tests were 7.8% (range, 4.9% to 11.5%) and 8.2% (range, 5.4% to 12%), respectively. These values were not significantly different. These data confirm that HbA, alone or in combination with a 50 gm glucose screen is not a sensitive screening tool for the detection of gestational diabetes mellitus.

Diabetes Mellitus↗
PubMed1982

Risk factors for breast cancer in women in northern Alberta, Canada, as related to age at diagnosis.

A population-based case-control study involving interviews with 577 female breast cancer patients and 826 controls in northern Alberta. Canada, revealed that some determinants of breast cancer varied according to age. Among women under age 45, risk factors included a younger age at menarche, late age at last birth, high parity, and recent use of oral contraceptives. At older ages risk was related to natural as opposed to surgical menopause, late age at first birth, low parity, late age at natural menopause, and tonsillectomy. At all ages there was an increased risk of breast cancer associated with difficulty in conceiving, benign breast disease, not having breast fed, and a history of breast cancer among mothers or sisters. For some variables the age differences were pronounced; the combination of low parity and late age at first birth was associated with a sevenfold increase in breast cancer risk at risk at ages 55-80 but a slight decrease at ages under 45. The effect of tonsillectomy steadily increased with age and represents a new lead, but certain features of the data suggest that the link to oral contraceptives among among younger women and the inverse relation to breast feeding at all ages may not be causal. Even though design limitations (cases interviewed in a different setting from controls) appeared not to influence conclusions, the results may have been subjected to interview bias and thus should be interpreted cautiously.

Adult↗
PubMed1980

Synthesis of secretory component by rat hepatocytes in culture.

Normal rat hepatocytes were isolated and cultivated in vitro. Synthesis of secretory component was demonstrated by its accumulation in the culture medium, as measured by radioimmunoassay; by incorporation of 14C-leucine in the protein specifically precipitated with anti-secretory component antiserum; and by a positive precipitin reaction of concentrated culture medium with the same antiserum. The results explain the high levels of secretory component found in rat bile and render plausible a mechanism of hepatic IgA transfer involving secretory component as the hepatocyte membrane receptor for polymeric IgA.

Animals↗
PubMed1980

SEM study of adult rat hepatocytes from preneoplastic and hyperplastic foci induced in the liver by diethylnitrosamine.

Oral administration of diethylnitrosamine (DENA) at the final concentration of 70 mg/kg, 24h after partial hepatectomy induces the appearance of preneoplastic foci composed of structurally altered and enzymatic deficient liver parenchymal cells of large size. These lesions grow up and form hyperplastic nodules, 0.5 to 2mm in diameter, 9 to 10 months after DENA treatment. Adult rat hepatocytes were isolated by collagenase perfusion from treated rats, sacrificed 6 months after the carcinogen application. They were separated by elutriation in distinct subpopulations, according to cell size and degree of ploidy. Fractions elutriated at high flow rates are enriched in preneoplastic hepatocytes of large size, which display a heterogeneous distribution of microvilli. Hyperplastic nodules were examined in situ by scanning electron microscopy, in 1 to 2 mm thick tissue slices, 10 months after the carcinogen administration. The nodules, easily detected at this stage of transformation, are composed of hypertrophied hepatocytes which exhibit heterogeneous cell surfaces. The parenchymal cells reveal frequently reduced interhepatocytic faces provided with sinuous bile canaliculi and sinusoidal faces covered with closely apposed, short microvilli.

Animals↗
PubMed1979

False negative mammograms causing delay in breast cancer diagnosis.

Eighty patients with negative mammograms and proven breast cancer are described. The incidence of negative mammograms is 5 to 7% of all breast cancer in Northern Alberta. In 30 patients, immediate biopsy because of clinical abnormality, and mastectomy, revealed only 3.3% axillary node involvement. The remaining 50 patients gave a history of finding a lump and then had a negative mammogram. Biopsy was delayed for a mean of 45 weeks. Their incidence of axillary node involvement was 42%. The mean age of both groups of patients was seven to eight years younger than the mean for all breast cancer patients. The implications of such delay on prognosis and survival are obvious. More public and medical education is needed.

Adult↗
PubMed1977

Ultrastructural and metabolic studies of isolated and cultured hepatocytes.

Cells isolated from adult rat liver form distinct cell populations: the parenchymal cells or hepatocytes and the non-parenchymal cells, mainly endothelial and Kupffer cells. These two groups are easy to separate by centrifugation methods, including centrifugal elutriation. The single-cell suspension of hepatocytes seems to be constituted of subfractions which are located roughly in the centrilobular and perilobular regions of the liver lobule and are differentiated so that they form cell lines with distinct metabolic activities. The basic means of characterizing the isolated hepatocytes consists of determining their size distribution, their sedimentation and elutriation properties, and their metabolic activities. Cultures of hepatocytes offer the possibility of prolonging their survival and of studying the differentiation of new bile canaliculi and the reconstitution of biliary polarity in the cytoplasm. The combination of Kupffer cells with hepatocytes improves the culture condition, as a result of elimination of cell debris by phagocytosis by the non-parenchymal cells. The application of the isolation and partition methods to pre-neoplastic liver allows us to classify the cells according to their degree of hyperplasia and opens up a new field of investigation.

Animals↗
PubMed1975

Isolation of centrolobular and perilobular hepatocytes after phenobarbital treatment.

Daily phenobarbital (PB) injections, on 3-7 consecutive days, induce an intense proliferation of smooth endoplasmic reticulum (ER) associated with a decrease of the glucose-6-phosphatase activity. This situation first affects the centrolobular hepatocytes, enhancing the degree of liver lobule heterogeneity. This experimental model was used for isolation and further subfractionation of hepatocytes on Ficoll density gradients, as described in the preceding paper. Profiles of protein, DNA, RNA, glycogen, phosphorylase, and glucose-6-phosphatase were determined all along the gradient. Two liver cell populations were distinguished: (a) light hepatocytes (mean density 1.10) present the same morphological characteristics as centrolobular cells, i.e., an abundant smooth ER composed of tubular elements, numerous small mitochondria, and few glycogen particles; (b) heavy hepatocytes (mean density 1.14) are characterized by large and compact glycogen areas and prominent rough endoplasmic cisternae, as are the perilobular cells. After incubation in the Wachstein-Meisel medium, Centrolobular hepatocytes exhibit dispersed reaction sites of glucose-6-phosphatase activity, whereas perilobular cells present a continuous and intense reaction. Morphometric determinations were carried out for both cell populations. Centrolobular PB hepatocytes are considerably enlarged (mean diameter: 23.7 mum); perilobular hepatocytes have a significantly smaller mean diameter of 19.2 mum, which is close to the values of control liver cells.

Animals↗