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Biomedical subjects

H Benediktsson

Publications and source records attributed to H Benediktsson.

54 records · Page 3Linked to original sources
PubMed1990

Xenoantibodies in the rat against guinea pig tissues.

The role of naturally occurring antibodies in discordant xenograft rejection is poorly defined. This is partly attributable to a lack of information regarding their tissue specificity and titers. Sera from different rat strains were studied for naturally occurring antibodies against guinea pig tissues using immunofluorescence and immunoperoxidase staining techniques. All sera contained IgG and IgM antibodies in low titers against erythrocytes, lymphoid cells, and a variety of tissue structures. Intentional immunizations of adult rats with guinea pig cells resulted in the production of xenoantibody specificities that were not detectable in nonimmunized animals. Immunizations of Munich-Wistar rats with guinea pig skin grafts occasionally resulted in the formation of antibodies that reacted with allogeneic and syngeneic cells of the liver, lung, and lymphoid organs. We conclude that rats have low titers of naturally occurring xenoantibodies against various tissue structures of the guinea pig, but their importance in xenograft rejection remains to be established.

Animals↗
PubMed1990

Pathogenesis of chronic bacterial prostatitis in an animal model.

A reproducible rat model of chronic bacterial prostatitis was developed using a defined bacterial pathogen (Escherichia coli) to study the pathogenesis and persistence of chronic bacterial prostatitis. The progression of inflammation and its consequences from acute to chronic prostatitis were documented with microbiological, histological, ultrastructural and immunological data. Chronic bacterial prostatitis in this model was associated with sparse glycocalix-enclosed protected bacterial microcolonies within the prostatic acini and ducts which appeared to stimulate a persistent local and systemic immunological reaction resulting in chronic inflammation of the gland. This model has many striking similarities to the natural history of human chronic bacterial prostatitis.

Animals↗
PubMed1988

T-lymphocyte subsets in the human lacrimal gland.

This study examines the microscopical appearance, location, distribution, subdivision and density of T-lymphocytes in the human lacrimal gland. Fourteen glands, 7 from either sex, were removed and frozen shortly after the donors' death, and processed for immunoperoxidase staining, utilizing a biotinavidin system and one of the following monoclonal antibodies: Anti-Leu-1 and -Leu-4, which recognize T-lymphocytes, anti-Leu-2a, which binds to suppressor/cytotoxic T-cells, and anti-Leu-3a + 3b, which recognizes helper/inducer cells. The T-lymphocytes in the human lacrimal gland were small to medium sized, mainly located in the interacinar tissue, often adjacent to an acinus or close to a collecting duct. The median number of each T-cell subset per defined field (0.086 mm2) at x 500 magnification was as follows: Males: Leu-1: 3.1, Leu-2a: 4.9, Leu-3a + 3b: 2.8, Leu-4: 4.5. Females: Leu-1: 4.3, Leu-2a: 5.0, Leu-3a + 3b: 3.7 and Leu-4:5.8. The sex difference was not statistically significant. The helper/suppressor cell ratio in the human lacrimal gland was 0.57 for males and 0.74 for females.

Adult↗
PubMed1988

Mortality and cancer incidence among marine engineers and machinists in Iceland.

A retrospective cohort study of mortality and cancer morbidity was carried out among 295 marine engineers and 182 machinists with special regard to cancer of the lung. The cohort was defined as all graduates from engineering and machinists school in Iceland during 1936-1955. During vocational training, as well as in their professional lives, marine engineers and machinists are exposed to asbestos, different kinds of mineral oils, and exhaust gases with marked individual variation as regards mode and magnitude of exposure. For deaths occurring between 1951 and 1982 information was obtained from the Statistical Bureau of Iceland. Significantly increased standardized mortality ratios were determined for cancer of the trachea, bronchus, and lung for the entire cohort. Record linkage with the Cancer Register revealed 36 cancers in the period 1955-1982. No statistically significant excess was found for the overall cancer incidence or for the incidence of cancer at any particular site. A special survey of smoking status showed that cigarette smoking was not as common among the subjects of the cohort as among the general male population in Reykjavik. These results support the suggestion that the increased mortality of lung cancer in the study group had a causal relationship to occupational exposure, particularly to asbestos exposure.

Adult↗
PubMed1987

Tumours in Iceland. Hodgkin's disease and non-Hodgkin's malignant lymphomas. A histological classification and epidemiological considerations.

All cases of biopsy-proven Hodgkin's disease and non-Hodgkin's lymphomas submitted for histological diagnosis in Iceland during 1955-1982 and available for review were typed histologically, using the World Health Organization Classification for cases of Hodgkin's disease and the "International Working Formulation" for cases of non-Hodgkin's lymphoma. A total of 92 cases of Hodgkin's disease were classified with a male-to-female ratio of 1.96. The largest subgroups were those of nodular sclerosis (42%) and mixed cellularity (32%). A prominent peak in the incidence was found in the 21-30 years age group. The incidence and subtypes of Hodgkin's disease in Iceland appears similar to those found in other Western countries. A total of 90 cases of non-Hodgkin's lymphomas were classified with a male-to-female ratio of 1.5. A high incidence of large cell lymphomas was found, especially of the immunoblastic type (35%), while in other respects the distribution of subtypes appeared similar to what has been found in studies from other Western countries. The incidence of non-Hodgkin's lymphomas in Iceland is low during childhood and young adulthood but rises sharply after age 50 and the overall incidence is similar to that found in other European countries.

Adolescent↗
PubMed1983

Melanocyte colonization of nodal metastasis from oral carcinoma.

Melanocyte colonization of metastases in cervical lymph nodes is described. The tumor was a squamous carcinoma of the floor of the mouth, metastasizing to cervical lymph nodes. The melanocytes were easily visible on sections of the nodes stained with hematoxylin and eosin and were confirmed by Masson-Fontana staining. Multiple sections through the oral primary tumor failed to show melanocyte colonization of the tumor. This is the second report of this phenomenon and represents only the third known case of this entity.

Carcinoma, Squamous Cell↗
PubMed1982

Lamellar bodies in benign and malignant schwannomas.

A light and electron microscopic study was done on seven cases of schwannomas, four of which were benign and three were malignant. Spherical or oval cytoplasmic inclusion bodies, one to three microns in diameter, were detected in all cases. These inclusions were demonstrable by Luxol fast blue stain. Ultrastructurally, the inclusions appeared as whorls of cell membranes reminiscent of myelin sheath. These lamellar bodies probably reflect the peculiar membrane characteristics of Schwann cells, and they provide a useful marker for recognition of benign or malignant schwannomas.

Humans↗
PubMed1981

Renal transplant uptake of technetium-99m sulfur colloid in various time periods after transplantation.

The uptake of technetium-99m sulfur colloid (TSC) by transplanted kidneys undergoing rejection has been described. In this retrospective study, the value of TSC uptake in diagnosing renal rejection was studied in different time intervals after renal transplantation. Within 14 days after transplantation, increasing uptake was seen in 88% of 26 rejection episodes. In patients with acute tubular necrosis, 42% of their studies showed TSC uptake. TSC did not predict rejection within the three days prior to rejection. Sensitivity, specificity and accuracy of 128 TSC studies were compared at different thresholds of TSC uptake; at best, accuracy was only 76%. In later time intervals, a much smaller percentage of patients had increasing uptake with rejection; this tendency was to remain unchanged. Many non-rejection studies showed some TSC uptake. In chronic rejection, persistently marked uptake dominated prior to one year after transplantation, but not beyond this. Thus, within 14 days after transplantation, TSC uptake may support the diagnosis of rejection. Thereafter its value becomes greatly limited.

Evaluation Studies as Topic↗
PubMed1980

Immunohistochemical evaluation of a complex endocrinopathy.

A patient with clinical and biochemical evidence of ectopic ACTH production is described. Autopsy revealed endocrine tumors of bronchus and pancreas with metastases to the liver, kidney, abdominal lymph nodes, and bone. Immunohistochemical methods established that the bronchial and pancreatic tumors were separate primary neoplasms each with its own hormone production; and allowed us to determine that the bronchial carcinoid was the source of ACTH and gave rise to the liver metastases, and that insulin was present in the cells of the pancreatic islet cell tumor. These methods also revealed a mild C-cell hyperplasia of the thyroid gland. We wish to stress the importance of the immunoperoxidase method in the evaluation of this and similar polyendocrine cases.

ACTH Syndrome, Ectopic↗
PubMed1976

Marfan syndrome with coronary artery lesions in a North American Indian.

Marfan syndrome has not been well documented in North American Indians. A 19-year old Ojibwa man had evidence of this syndrome -- specifically, tall stature, long, thin extremities (particularly, fingers and toes), increased urinary excretion of hydroxyproline, aortic aneurysm, aortic regurgitation and pathologic evidence of aortic rupture and alastic tissue fragmentation. Intimal hyperplasia was present in the extramural coronary arteries, while the intramural arteries, usually thought to be involved, were normal.

Adult↗
PubMedDate not supplied

PG490-88, a new immunosuppressant, effectively prevents acute and chronic rejection in rat renal allografts.

PG490-88 is a semisynthetic derivative of the novel compound PG490 (triptolide) purified from a Chinese herb. It has been shown to prolong acute allograft survival in multiple experimental organ transplant models. However, the effect of PG490-88 on prevention of acute and chronic renal allograft rejection has not been determined. Kidneys of ACI or F344 rats were transplanted into bilaterally nephrectomized LEW recipients as the acute or chronic allograft rejection models, respectively. Treatment of LEW recipients with PG490-88 significantly prolonged ACI kidney graft survival in a dose-dependent manner when compared with the untreated allograft controls. LEW recipients of F344 kidney grafts who received PG490-88 for 90 days with a brief course of low-dose FK506 showed normal serum creatinine levels and markedly reduced histological changes of chronic rejection at day 90 after transplantation. These results suggest that PG490-88 significantly prolongs kidney allograft survival in an acute rejection model and prevents chronic allograft rejection in rats.

Acute Disease↗
PubMedDate not supplied

Expression of platelet-derived growth factor receptor in rat heart allografts.

Growth factors may play a role in the tissue remodeling of long-surviving allografts. The aim of these experiments was to investigate the pattern of expression of platelet-derived growth factor and epidermal growth factor receptors in relation to the immunohistopathology of rat cardiac allografts. Heart grafts were transplanted between LEW and F344 and LEW.1A and LEW.1AR2 strains and removed for analysis at graft asystole or at predetermined time intervals. The grafts were studied with direct and indirect immunofluorescence and immunoperoxidase staining techniques and monoclonal antibodies against T lymphocytes, monocytes/macrophages, and endothelium. Expression of growth factor receptor was studied with the use of a monoclonal antibody against the platelet-derived growth factor-beta receptor and autoradiography with platelet-derived growth factor-BB or epidermal growth factor labeled with iodine 125. Increased expression of platelet-derived growth factor-beta receptors was observed in the media of graft arteries and in a number of myocardial cells in association with infiltration of the graft with T cells and monocytes/macrophages. Autoradiography with epidermal growth factor labeled with 125I failed to show changes in the binding pattern in relation to rejection. Upregulation of platelet-derived growth factor receptors may suggest involvement of platelet-derived growth factor in the tissue remodeling that occurs in conjunction with chronic rejection.

Animals↗