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Biomedical subjects

J G Jónasson

Publications and source records attributed to J G Jónasson.

18 recordsLinked to original sources
PubMed2005

Gastric glassy cells: a study of 3202 gastrectomy specimens from dwellers of the Atlantic and Pacific basins.

Fifteen years ago we detected gastric cells with glassy cytoplasm (GCs) in the human pyloric antrum. The frequency of these cells was subsequently investigated in sections from gastrectomies carried on in populations dwelling on the rim of the Atlantic and Pacific basins. In this work we compared the results obtained in these disparate geographic regions. We reviewed sections from 3203 gastrectomies (1942 in the Atlantic basin and 1261 in the Pacific basin). In the Atlantic basin 12/1942 (0.6%) of the gastrectomies had GCs, whereas in the Pacific basin 26/1261 (2.1%) of the gastrectomies had GCs. The difference was significant (p<0.05). The proportion of gastrectomies with GCs was higher in patients in Vancouver, Canada, than in New York, and higher in Santiago de Chile than in Buenos Aires, despite the fact that these populations reside at approximately the same geographic latitude. Previous studies with the same material indicated that both the extension of intestinal metaplasia and the frequency of ciliated metaplasia were significantly higher in the Pacific than in the Atlantic basin. Hence, the difference in the frequencies of GCs appears to be a new indication that dissimilar environmental exposures in the two basins might have influenced the histological make-up of the gastric mucosa.

Aged↗
PubMed2001

Risk of breast cancer in female flight attendants: a population-based study (Iceland).

OBJECTIVES: To study whether increased cancer risk, particularly of cancer types previously related to radiation, was found among cabin attendants, using employment time as a surrogate of exposure to cosmic radiation. METHODS: A cohort of 1690 cabin attendants, 158 men and 1532 women from the Icelandic Cabin Crew Association and two airline companies in Iceland, was established. Cancer sites were ascertained between 1955 and 1997 by follow-up in a cancer registry. The personal identification number of each subject was used in record linkage to population-based registers containing vital and emigration status, reproductive factors and histologically verified cancer diagnosis. Standardized incidence rates (SIR) of different cancer sites in relation to employment time and year of hiring were calculated, as well as predictive values of breast cancer risk for evaluating possible confounding due to reproductive factors. RESULTS: The total number of person-years was 27,148. Among the women, 64 cancers were observed whereas 51.63 were expected (SIR 1.2, 95% CI 1.0-1.6), and significantly increased risk for malignant melanoma (SIR 3.0, 95% CI 1.2-6.2) was found. Significantly increased risks of overall cancers (SIR 1.3, 95% CI 1.0-1.8) and breast cancer (SIR 1.6, 95% CI 1.0-2.4) were observed among the female cabin attendants when 15 years lag time was applied. Those hired in 1971 or later had the heaviest exposure to cosmic radiation at a young age and had significantly increased risk of overall cancer (SIR 2.8, 95% CI 1.4-4.9) and breast cancer (SIR 4.1, 95% CI 1.7-8.5). Predictive values calculated on the basis of reproductive factors among the cabin attendants and the population, and risk of breast cancer were 1.0 for parous vs. nulliparous, 1.0 for number of children, and 1.1 for age at birth of first child. CONCLUSION: The increased risk of breast cancer and malignant melanoma among cabin attendants seems to be occupationally related. The part played by occupational exposures, i.e. cosmic radiation, disturbance of the circadian rhythm, and electromagnetic fields or combination of these factors in the etiology of breast cancer among the cabin crew, is still a puzzle as confounding due to parity appears to be ruled out. The relationship between the sunbathing habits of the cabin crew and the increased risk of malignant melanoma needs to be clarified. There is also an urgent need to elucidate the importance of these findings for today's aviation.

Adult↗
PubMed2001

[Carcinoma of the colon in Iceland 1955-1989. A study on pathology.].

OBJECTIVE: The objective of this study was to investigate various pathological parameters of colon carcinoma in Iceland in the 35 year time period from 1955-1989, and changes in these parameters during the study period. MATERIAL AND METHODS: Information on all patients diagnosed with colon carcinoma in the study period was obtained from the Icelandic Cancer Registry. All pathology reports and autopsy reports were checked. All pathology samples were reviewed and the tumours reevaluated, reclassified, tumour location determined, the tumours graded and Dukes staged and age standardized incidence was calculated according to revised diagnosis. Cancers in polyps are included in the study. The study period was separated into seven five year periods and changes in pathological parameters investigated according to time periods. RESULTS: After reevaluation of the tumours 1205 fulfilled the criteria for the diagnosis of colon carcinoma, 572 in men and 633 in women. The incidence increased in the study period for men from 8.2 to 21.5/105 and for women from 7.9 to 15.8/105. The pathological parameters were determined for 1109 tumours. Adenocarcinoma NOS was the most common diagnosis or 90.1% of the tumours and mucinous carcinomas came second. Most of the tumours were located in the sigmoid colon (38.6%), 19.1% in the coecum and 14.5% in the ascending colon. No significant observed changes occurred in tumour location in the study period. The mucinous histological type and signet ring tumour type were more common in the right colon. In Dukes staging of the tumours 9.1% were in stage A, 32.1% in stage B, 24.6% in stage C and 22.7% in stage D, whereas 11.5% proved indeterminate. A minimal trend to increase in Dukes A tumours was observed in the latter half of the study period, overall no significant changes in Dukes classification could be pinpointed in the time period. Most of the tumours were of intermediate tumour grade or 70.1%, but 16.5% were well differentiated and 13.4% were poorly differentiated. A much higher percentage of poorly differentiated tumours were present in the right colon in comparison to the left colon. A poorer differentiation of the tumours went hand in hand with worse Dukes stage of tumours. CONCLUSIONS: We conclude that: 1. the incidence of colon carcinoma has much increased during the study period for both sexes, 2. observed changes in studied pathological parameters over the study period were minimal. Of interest is the minimal change in Dukes stages of colon cancer in the study period.

English Abstract↗
PubMed2001

[Hepatocellular carcinoma in Iceland.].

INTRODUCTION: The incidence of hepatocellular carcinoma (HCC) varies throughout the world, being relatively low in Northern Europe (less than five per 100,000 population) where the majority of the patients have cirrhosis. In Iceland the prevalence of viral hepatitis and cirrhosis, the main risk factors for HCC, is lower than reported in many other countries. The aim of our study was to investigate the incidence and etiology of HCC in Iceland. MATERIAL AND METHODS: All patients diagnosed with HCC in Iceland in 1984-1998 were included in the study. Histologic diagnosis was required for inclusion. Patients were identified from the Icelandic Cancer Registry and by reviewing autopsy and histopathology reports. Further information was obtained from medical records. RESULTS: A total of 71 cases of HCC were identified, 51 males and 20 females. The mean age for males was 69.3 years (18-95) and 73 years (52-89) for females. The age-standardized annual incidence rate of HCC was 1.08/100,000 (males 2.10, females 0.67). The incidence did not increase significantly during the study period. Alcohol abuse (15.5%) and hemochromatosis (11%) were the most common risk factors. Twenty-three (32%) had cirrhosis but 39 (55%) had no known risk factors. Of 55 cases where non-neoplastic tissue was available for examination, 27 had liver disease. CONCLUSIONS: 1) The incidence of HCC in Iceland is lower than reported in other countries. 2) Alcohol abuse and hemochromatosis are the most common risk factors. 3) The ratio of patients with cirrhosis is low.

English Abstract↗
PubMed2000

Altered expression of E-cadherin in breast cancer. patterns, mechanisms and clinical significance.

Reduced cell adhesion brought about by altered surface expression of E-cadherin has been implicated in invasive and metastatic malignant growth. We investigated the patterns of immunohistochemical E-cadherin expression in 120 breast carcinomas. Furthermore, we analysed DNA from the same samples for loss of heterozygosity (LOH) using three separate microsatellite markers on chromosome 16q22.1. Finally, the clinical outcome was ascertained for 108 patients. 19% (18/97) of infiltrating ductal carcinomas showed complete loss of E-cadherin expression compared with 64% (9/14) of infiltrating lobular carcinomas. LOH was detected in 46% (24/52) of infiltrating ductal carcinomas and 89% (8/9) of infiltrating lobular carcinomas. In the infiltrating lobular carcinomas, LOH was associated with complete loss of cell membrane expression of E-cadherin, although a cytoplasmic expression pattern was evident. In contrast, this association was not seen in the infiltrating ductal carcinomas. In a multivariate analysis, loss of E-cadherin expression was shown to be a significant independent risk factor for a poorer disease-free survival (P=0.019), in particular in the node-negative subset of patients (P=0.029). Significance was also approached for breast cancer corrected survival (P=0.056). We conclude that different mechanisms are involved in the altered E-cadherin expression seen in different subtypes of breast carcinomas. Furthermore, we implicate loss of E-cadherin, regardless of the genetic causes, as an independent prognostic marker for disease recurrence, especially in node-negative breast cancer patients, irrespective of the histological type.

Adult↗
PubMed2000

Intracellular Fas ligand in normal and malignant breast epithelium does not induce apoptosis in Fas-sensitive cells.

Fas ligand (FasL) is expressed on some cancers and may play a role in the immune evasion of the tumour. We used immuno-histochemistry to study the expression of Fas and FasL in tissue samples from breast cancer patients, as well as normal breast tissue. Our results show that Fas and FasL are co-expressed both in normal tissue and in breast tumours. Fas and FasL mRNA were expressed in fresh normal and malignant breast tissue, as well as cultured breast epithelium and breast cancer cell lines. Flow cytometry analysis of live cells failed to detect FasL on the surface of normal or malignant breast cells; however, both stained positive for FasL after permeabilization. Fas was detected on the surface of normal breast cells and T47D and MCF-10A cell lines but only intracellularly in other breast cell lines tested. Neither normal breast epithelium nor breast cell lines induced Fas-dependent apoptosis in Jurkat cells. Finally, 20 tumour samples were stained for apoptosis. Few apoptotic cells were detected and there was no increase in apoptotic cells on the borders between tumour cells and lymphocytes. We conclude that FasL is expressed intracellularly in both normal and malignant breast epithelium and unlikely to be important for the immune evasion of breast tumours.

Animals↗
PubMed2000

Serum thyroglobulin as a risk factor for thyroid carcinoma.

Samples from a biological serum bank taken up to 23 years prior to diagnosis of thyroid carcinoma were analysed for human thyroglobulin, thyroid-stimulating hormone and thyroxin. After exclusions, the final study material consisted of 59 cases of papillary and follicular carcinomas. These cases were compared with 164 controls, matched for sex, age and time of sample taking. The most interesting finding was that concentrations of thyroglobulin in serum were abnormally elevated in cases compared with controls, equal to or above 30 microg/L, with odds ratio 7.0 (CI 3.1-15.7). This elevation of serum thyroglobulin occurred in 44% of the carcinoma cases. Sensitivity was around 50 for measurements taken up to 15 years prior to diagnosis, but 21 when the interval was over 15 years. Specificity was 89. No differences were found between cases and controls in values for thyroid-stimulating hormone and thyroxin.

Adenocarcinoma, Follicular↗
PubMed2000

[Liver metastases of unknown origin.].

OBJECTIVE: Approximately 5% of cancer patients are diagnosed with tumour of unknown origin (3-4% in Iceland). Of those 10-30% have liver metastases. Liver metastases of unknown origin is thus not an uncommon problem. In the present study information about the origin and histology of liver metastases of unknown origin was compiled. MATERIAL AND METHODS: Records of all biopsies from liver metastases performed in the years 1987-1996 were retrieved from the medical database of the Department of Pathology at the University of Iceland. The biopsies came from a group of 176 patients. Ninety-two cases, in which the origin of the primary tumour was suspected or known, were excluded from the study, leaving 84 cases where the primary was completely unknown. The database of the Icelandic Cancer Society was used to gather data about the final tissue diagnosis and the location of the primary tumour when known. RESULTS: The Cancer Society data revealed the location of the primary tumour in 55 of the 84 cases of liver metastases of unknown origin. The most prevalent (75%) primary tumours were cancers of the pancreas (15), lung (13) and colon/rectum (12). The tissue diagnosis was adenocarcinoma in 33 of the 55 cases. In the male patients 83% of the adenocarcinoma metastases came from the colon/rectum or pancreas. The corresponding figure for the female patients was 67%, while 20% of the tumours in females originated in the gallbladder and biliary tree. CONCLUSIONS: In two thirds of the cases of liver metastases of unknown origin the primary tumour was later discovered. The most prevalent tumours were cancers in the pancreas, lung and colon/rectum. Adenocarcinoma was the tissue diagnosis in 60% of cases.

English Abstract↗
PubMed1999

Enhanced B cell survival in familial macroglobulinaemia is associated with increased expression of Bcl-2.

A family with three cases of macroglobulinaemia of undetermined significance (MGUS), and one case each of immunoblastic lymphoma, Waldentröm's macroglobulinaemia and multiple myeloma was first described 20 years ago. We have previously identified 10 out of 35 healthy family members tested whose lymphocytes produced abnormally high amounts of immunoglobulins in culture. In the present study lymphocyte subpopulations of these hyper-responders have been further characterized and lymphocyte reactivity and survival in vitro have been studied. No differences were detected in the proportions of resting B lymphocytes (CD19+) co-expressing CD5, CD10, CD11b, or CD38, and the CD4/CD8 ratio of T cells was normal before and after stimulation with pokeweed mitogen (PWM). The initial rate of response in terms of immunoglobulin production was not increased, but immunoglobulin levels continued to rise during the second week of culture whereas the production peaked at 8 days in control cultures. This was associated with significantly greater survival of lymphocytes and at 14 days surviving B cells could only be identified in samples from hyper-responders. A lymph node removed because of tuberculosis from a family member 23 years before the diagnosis of multiple myeloma showed very marked Bcl-2 expression in a B cell follicle. This was not seen in a tuberculous lymph node from an unrelated subject. Stimulated cultures from three hyper-responders tested demonstrated significantly higher retention of Bcl-2 in B cells compared with one family control and six unrelated controls. We conclude that the increased production of immunoglobulins previously observed in this family with an inherited tendency for benign and malignant B cell proliferation is the result of enhanced B cell survival, which is associated with increased expression of Bcl-2 following stimulation.

B-Lymphocyte Subsets↗
PubMed1999

Metanephric adenoma.

A 59-year old woman was diagnosed with a tumour in her right kidney. A nephrectomy was performed, and a 45 mm diameter tan-pink coloured tumour was found. Microscopy revealed small, dark cells in organized arrays of small round acini and tubules with glomeruloid infoldings. A diagnosis of metanephric adenoma was made. The tumour cells proved diploid on flow cytometry and immunohistochemical staining was positive for CAM 5.2 and AE-3. FISH analysis of three chromosomes did not reveal any abnormal karyotype. It is important to differentiate metanephric adenoma from renal cell carcinoma and adult Wilm's tumour, since it has a benign course.

Adenoma↗
PubMed1998

The effects of IL-6 on cell adhesion and e-cadherin expression in breast cancer.

Interleukin 6 (IL-6) is a pleiotropic inflammatory cytokine and its role in cancer is not yet clear. The effects of IL-6 on four breast cancer cell lines and normal mammary epithelium, cultured from milk were tested. Four different patterns of response to IL-6 were found depending on the differentiation status of the cells. In normal mammary epithelial cultures, the effects of IL-6 were mainly growth inhibitory, whereas in MCF-7, IL-6 had growth inhibitory and anti-adhesive effects. In T-47D and ZR-75-1 the anti-adhesive effects were prominent although the growth inhibitory effects were not. These anti-adhesive effects were associated with epithelioid to fibroblastoid morphological changes and a local decrease in E-cadherin expression. In the highly invasive cell line MDA-MB-231, which does not express E-cadherin, no effects of IL-6 were seen. IL-6 levels in the serum of 60 breast cancer patients were found to be increased in 27% (16/60) compared to 2% (1/50) in a control group. Furthermore, it was found that altered E-cadherin expression was seen in 69% of the primary tumours, although no significant association was found between raised serum IL-6 levels and altered E-cadherin expression. Finally IL-6 serum levels did not effect the survival of breast cancer patients. The authors therefore implicate IL-6 as a possible factor important in breast cancer progression and metastasis formation, although the clinical significance of this cytokine in breast cancer patients could not be established.

Breast↗
PubMed1997

A comparison of cytogenetic studies and flow cytometry in breast carcinomas.

In this study, we compared genetic instability in 70 breast carcinomas analyzed by two different methods, cytogenetics and flow cytometry. This comparison showed that each method has its strengths and weaknesses. Flow cytometry detected aneuploidy in 60% of cases, but missed most of the cytogenetically near-diploid clones and clones with simple chromosomal changes. Cytogenetics revealed chromosomal abnormalities in 50% of the samples. Simple chromosomal changes and multiploidy were readily detected by this method, but some of the clones with a high DNA index by flow cytometry were missed. The two methods gave corresponding results in the majority of cases (54%). In 17 cases, both methods detected matching abnormal clones (r = 0.93) but the DNA index was higher than predicted by the chromosome numbers. Most of the discrepancies might be explained by tumor heterogeneity and insufficient numbers of cells available for cytogenetic analyses. In seven cases, single-cell abnormalities were found that corresponded to a flow cytometry peak. Multiclonality was present in 25% of aneuploid tumors. No association was found between metaphases in cytogenetic preparations and increased S-phase fraction of the tumors, but aneuploid tumors had a significantly higher proliferation rate. Pooling data from both methods demonstrated that the majority of our samples were aneuploid (74%).

Breast Neoplasms↗
PubMed1994

Nuclear DNA analysis and prognosis in carcinoma of the thyroid gland. A nationwide study in Iceland on carcinomas diagnosed 1955-1990.

The purpose of this study was to ascertain whether DNA ploidy status and S-phase fraction affected the prognosis of patients with carcinoma of the thyroid gland. We reviewed all malignant thyroid tumours diagnosed in Iceland from 1955 to 1990. In all, 494 thyroid carcinomas were diagnosed during that period. By analysing tumour material from paraffin blocks by flow cytometry we were able to evaluate the ploidy status in 424 tumours and the S-phase value in 417 tumours. We detected aneuploid cell populations in 9.7% of papillary carcinomas, 24.3% of follicular carcinomas, 42.9% of medullary carcinomas and 78.6% of anaplastic carcinomas. Some 57% of tumours, mainly papillary carcinomas, had an S-phase value of less then 3%, whereas most of the other histological types of carcinoma, including all the anaplastic tumours, had an S-phase value of > or = 3%. Univariate analysis indicated that both ploidy status and S-phase fraction were significant variables. When taking into account known prognostic variables of thyroid carcinoma in a multivariate analysis, however, neither ploidy status nor S-phase value proved significant. We conclude that DNA ploidy status and S-phase values are not independent prognostic factors in thyroid carcinoma.

Adult↗
PubMed1993

Flow cytometric DNA analysis of adenocarcinomas of the vermiform appendix. Brief report.

The DNA ploidy status and S-phase fraction of eight adenocarcinomas of the vermiform appendix diagnosed in Iceland during 1974-1990 were analyzed by flow cytometry. Four cases were classified as Dukes' stage B2 and four cases as Dukes' stage D. Seven tumors were diploid and one was aneuploid. The DNA aneuploid tumor was the only one which metastasized outside the abdominal cavity. The S-phase fraction in general was low. The results of this study do not indicate any significant correlation between ploidy status and clinical behavior.

Adenocarcinoma↗
PubMed1989

Tumours in Iceland. 11. Malignant tumours of the thyroid gland. A histological classification and epidemiological considerations.

All malignant primary tumours of the thyroid gland submitted for histological diagnosis in Iceland during the 30 years 1955-1984, and available for review, were typed histologically according to the World Health Organization classification but also taking into account the more recent well recognized follicular variant of papillary carcinoma. A total of 480 thyroid tumours were classified with a female--to male ratio of 2.8 (367 females, 129 males). The age distribution is much what would be expected, the anaplastic type of carcinomas occurring in the elderly while papillary and follicular tumours occur over a much wider age range. The incidence of thyroid carcinomas in Iceland is about 2-3 times higher than in the other Nordic countries. This is largely due to an unusually high incidence of the papillary type of carcinoma. Overall, the papillary carcinoma accounted for 80% of thyroid malignancies. The tumours diagnosed incidentally at autopsy were about 20% of the entire material, and these tumours were only of the differentiated types of thyroid carcinoma. Even if the incidentally diagnosed tumours are excluded, the percentage of papillary tumours is 77% which is unusually high. The papillary type of carcinomas occasionally occurred in familial clusters in Iceland but not sufficiently to account for the unusually high incidence. Some of the possible etiological factors are discussed.

Age Factors↗
PubMed1989

Tumors in Iceland. 12. Malignant tumours of the corpus of the uterus. A histological classification, epidemiological considerations and survival.

All malignant tumours of the corpus of the uterus diagnosed in Iceland during 1955-1984 and available for review were typed histologically, using both the WHO Classification and the more recent classifications proposed by the International Society of Gynecological Pathologists. Of a total of 391 tumours 53 were excluded for various reasons. Of the 338 remaining tumours 309 were carcinomas, 17 sarcomas, 10 mixed Müllerian tumors and 2 choriocarcinomas. The adenocarcinomas were by far the most common of the carcinomas, comprising 93%. The incidence of carcinomas is similar to that found in the other Nordic Countries. A considerable increase in the incidence of adenocarcinomas was observed during the survey period and this was largely due to a steady steep rise in incidence of the best differentiated or Grade I tumours. This might be looked at as supportive evidence for the etiological role of estrogen replacement therapy which has been in constantly increasing use during the latter two decades of the study period. The mean age at diagnosis increased during the survey period. Generally, survival of patients did not clearly improve during the period but, however, increased considerably for the better differentiated tumours. Finally, we give our evaluation of the two systems of classification used in the study.

Adenocarcinoma↗
PubMedDate not supplied

Gastric carcinomas of intestinal type concur with distant changes in the gastric mucosa. A multicenter study in the Atlantic basin.

Population studies in the Pacific Basin showed that gastric carcinomas of intestinal type often concur with distant mucosal changes (DMCs). In the present work, the presence of DMCs was investigated in populations dwelling in the Atlantic Basin. A total of 1737 gastrectomy specimens were reviewed: 627 in New York, 435 in Reykjavik, 198 in Buenos Aires, 186 in Florence, 174 in London and the remaining 117 in Stockholm. A total of 17,282 sections were carefully scrutinized. The following DMCs were investigated: intramucosal glandular cysts, gastric cells with ciliated metaplasia, with large or small mucus negative vacuoles, and extensive intestinal metaplasia (IM). The highest frequencies of DMCs were found in Florence for specimens with intestinal type carcinoma: 41.3% had intramucosal cysts, 22.4% had cells with ciliated metaplasia, 12.9% cells with large vacuoles, and 50.9% had high IM. The highest frequency of gastric cells with small vacuoles was recorded in New York (9.1%), also in specimens with intestinal type carcinoma. Significantly lower DMCs percentages were found in specimens with carcinomas of diffuse type, and miscellaneous gastric diseases. The occurrence of DMCs was not influenced to a significant degree by the number of sections available per gastrectomy. Since environmental factors trigger the evolution of intestinal type carcinomas and as DMCs also occurred in specimens without carcinoma-although at a significantly lower rate--it is conceivable that DMCs are also evoked by environmental factors (before a gastric carcinoma ensues). DMCs were found in specimens having intestinal carcinomas either in the cardia, the corpus or the antrum. Thus, DMCs seem to provide the adequate "soil" for the development of gastric carcinomas of intestinal type, independently of the future localization of that tumor in the stomach.

Adenocarcinoma↗