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Biomedical subjects

A Dare

Publications and source records attributed to A Dare.

13 recordsLinked to original sources
PubMed2000

Detection of abasic sites and oxidative DNA base damage using an ELISA-like assay.

Reactive oxygen species produce a wide spectrum of DNA damage, including oxidative base damage and abasic (AP) sites. Many procedures are available for the quantification and detection of base damage and AP sites. However, either these procedures are laborious or the starting materials are difficult to obtain. A biotinylated aldehyde-specific reagent, ARP, has been shown to react specifically with the aldehyde group present in AP sites, resulting in biotin-tagged AP sites in DNA. The biotin-tagged AP sites can then be determined colorimetrically with an ELISA-like assay, using avidin/biotin-conjugated horseradish peroxidase as the indicator enzyme. The ARP assay is thus a simple, rapid, and sensitive method for the detection of AP sites in DNA. Furthermore, removal of damaged base by DNA N-glycosylases generates AP sites that can be measured by the ARP reagent. By coupling the ARP assay with either endonuclease III from Escherichia coli or 8-oxoguanine N-glycosylase (OGG1) from yeast, investigators can rapidly determine the amount of oxidative pyrimidine damage (endonuclease III-sensitive sites) or purine damage (OGG1-sensitive sites) in cellular DNA, respectively. An increased level of oxidative damage has been implicated in several age-related human diseases such as Alzheimer's disease, amyotrophic lateral sclerosis, and Parkinson's disease, as well as the aging process. The sensitivity and simplicity of the ARP assay thus make it a valuable method for investigators who are interested in estimating the level of oxidative DNA damage in cells and tissues derived from patients with various age-related diseases or cancers.

Aldehydes↗
PubMed1999

Changes in haematological parameters and iron metabolism associated with a 1600 kilometre ultramarathon.

OBJECTIVE: To investigate haematological variations and iron related changes in the serum of participants in a 1600 kilometre ultramarathon run. PARTICIPANTS: Seven male and two female participants in a 1600 km foot race. METHODS: Blood samples were obtained from the participants before, after four and 11 days of running, and at the end of the event. Samples were analysed by standard methods for haemoglobin, packed cell volume, total red cell count, mean red cell volume, mean red cell haemoglobin, total white cell count and differential, platelets, reticulocytes, iron, ferritin, total iron binding capacity, percentage transferrin saturation, haptoglobin, and bilirubin and corrected for changes in plasma volume. RESULTS: The following variables decreased during the event (p < 0.05): haemoglobin, packed cell volume, mean red cell volume, percentage lymphocytes, percentage monocytes, serum iron, total iron binding capacity, and percentage transferrin saturation. Increases (p < 0.05) were found in plasma volume, total red cell count (day 4 only), total white cell count, percentage and absolute numbers of neutrophils and reticulocytes, absolute numbers of lymphocytes and monocytes (day 4 only), absolute numbers of eosinophils (day 11 and race end), absolute numbers of basophils (race end only), platelets, ferritin, haptoglobin, and bilirubin (day 4 only). CONCLUSION: Ultramarathon running is associated with a wide range of changes in haematological parameters, many of which are related to the normal acute phase response to injury. These should not be confused with indicators of disease.

Adolescent↗
PubMed1999

The biochemistry of runners in a 1600 km ultramarathon.

OBJECTIVE: To investigate biochemical changes related to muscle breakdown, hepatic damage, hyponatraemia, and a number of other variables in the serum of participants in a 1600 km ultramarathon run. METHODS: Blood samples were obtained from nine participants (seven men, two women) in a 1600 km foot race before, after 4 and 11 days of running, and at the conclusion of the event. Samples were analysed by standard methods and results corrected, where appropriate, for changes in plasma volume. RESULTS: Significant (p < 0.05) increases in the following variables were found during or at the conclusion of the event: plasma volume, sodium, chloride, urea, alkaline phosphatase, gamma-glutamyltransferase, alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, creatine kinase, bilirubin, total protein, albumin, glucose, calcium, and phosphate. Significant (p < 0.05) decreases in the following variables were found during or at the conclusion of the event: globulin, uric acid, and cholesterol. No change occurred in serum potassium, bicarbonate, creatinine, and triglycerides. CONCLUSION: A wide range of biochemical perturbations occur during ultramarathon running but a number of variables remain within normal limits despite severe physical stress. Large increases in plasma volume occur, and hyponatraemia is rare in events of this duration. The time course of increases in enzymic indicators of muscle damage indicates that duration of running is not the sole determinant of such increases. This study provides indirect evidence of possible hepatic damage during prolonged exercise and an increase in serum calcium both of which warrant further investigation.

Adult↗
PubMed1998

Histologic and immunohistochemical responses after aortic valve allografts in the rat.

BACKGROUND: Human aortic valve allografts elicit a cellular and humoral immune response. It is not clear whether this is important in promoting valve damage. We investigated the changes in morphology, cell populations, and major histocompatibility complex antigen distribution in the rat aortic valve allograft. METHODS: Fresh heart valves from Lewis rats were transplanted into the abdominal aorta of DA rats. Valves from allografted, isografted, and presensitized recipient rats were examined serially with standard morphologic and immunohistochemical techniques. RESULTS: In comparison with isografts, the allografts were infiltrated and thickened by increased numbers of CD4+ and CD8+ lymphocytes, macrophages, and fibroblasts. Thickening of the valve wall and leaflet and the density of the cellular infiltrate was particularly evident after presensitization. Endothelial cells were frequently absent in presensitized allografts whereas isografts had intact endothelium. Cellular major histocompatibility complex class I and II antigens in the allograft were substantially increased. A long-term allograft showed dense fibrosis and disruption of the media with scattered persisting donor cells. CONCLUSIONS: The changes in these aortic valve allograft experiments are consistent with an allograft immune response and confirm that the response can damage aortic valve allograft tissue.

Animals↗
PubMed1997

Effects of ionizing radiation on proliferation and differentiation of osteoblast-like cells.

Diagnostic radiation for immediate post-surgical assessment of osseointegrated dental implants has been discouraged, due to the possibility of detrimental effects of ionizing radiation on healing and remodeling of bone. To assess this possibility, we investigated the effects of ionizing radiation on proliferation and differentiation of osteoblasts using osteoblast-like cells isolated from the calvariae of newborn rats (ROB) and a clonal osteoblastic cell line (MC3T3-E1). The cells were exposed on day 3 to a single dose of x-rays at either 40, 100, 400, or 4000 mGy, respectively, from a linear accelerator radiotherapeutic machine (Linac) or a 40-mGy dose from a diagnostic chest x-ray machine. The effects of radiation on cell growth and alkaline-phosphatase-specific (ALP) activity were evaluated at three-day intervals after irradiation up to day 12 in ROB cells, and evaluated at day 12 in MC3T3-E1 cells. At the culture end-point, the effects on formation of bone-like nodules were also evaluated in both ROB and MC3T3-E1 cells. Exposure of 4000 mGy differentially affected the two cell types. It inhibited cell growth and alkaline phosphatase activity, and inhibited DNA content in MC3T3-E1 cells. This irradiation also strongly inhibited the formation of bone-like nodules in ROB cells. On the other hand, exposure of 40-, 100-, and 400-mGy (Linac) and 40-mGy (diagnostic quality) irradiation induced no significant changes in cell growth, alkaline phosphatase activity, and formation of bone-like nodules in ROB cells. These doses also induced no significant changes in DNA content and ALP activity in MC3T3-E1 cells. These results indicate that ionizing radiation at a single dose of up to 400 mGy induces no significant changes in cell growth and differentiation of osteoblast-like cells, at least in vitro. Higher radiation doses (4000 mGy) may exert different effects on cell proliferation and cell differentiation of osteoblasts, depending on the cell types affected. Thus, diagnostic radiation seems to have less effect on proliferation and differentiation of osteoblasts.

Alkaline Phosphatase↗
PubMed1996

Detection of Mycobacterium tuberculosis by PCR amplification with pan-Mycobacterium primers and hybridization to an M. tuberculosis-specific probe.

Nucleic acid amplification techniques such as the PCR are very useful in the rapid diagnosis of infections by Mycobacterium tuberculosis. However, recent studies have shown that the accuracy of results can vary widely when tests are performed with nonstandardized reagents. We have developed a PCR assay for the detection of M. tuberculosis that is both rapid and accurate. The assay reagents are standardized and quality controlled. False-positive results due to carryover contamination are prevented by the incorporation of dUTP coupled with uracil-N-glycosylase restriction. This assay also employs pan-Mycobacterium amplification primers, allowing for flexibility in the mycobacterial species that can be identified from a single amplification reaction. The amplification is very sensitive; amplification products generated from as few as three bacteria can be detected by agarose gel electrophoresis. DNAs isolated from 33 of 34 mycobacterial species tested were amplified efficiently. Only DNA from Mycobacterium simiae did not amplify. The amplification is also very specific. Amplification products were generated only from the DNAs of bacteria in closely related genera such as Corynebacterium. The nonmycobacterial amplicons do not pose a problem, as they do not hybridize to mycobacterium-specific probes. Hybridization of amplicons to an M. tuberculosis-specific probe allows for the unambiguous identification of M. tuberculosis complex organisms. The clinical performance of this PCR assay was evaluated against that of culture in 662 respiratory specimens. Sensitivities of 100 and 73.1% were obtained from smear-positive and -negative respiratory specimens, respectively. The corresponding specificities were 100 and 99.8%. The high sensitivity and specificity, coupled with the potential for detecting a wide range of mycobacteria, make this assay a useful tool in the clinical management of mycobacterial infections.

Bacteriological Techniques↗
PubMed1996

Clinical picture of tick-borne encephalitis among patients hospitalized in 1994 in the Department of Infectious Diseases Medical School Białystok.

In 1994 20 patients of the Department of Infectious Diseases, Medical School Białystok were diagnosed to have tick-borne encephalitis. The etiologic agent was identified by serologic studies of the serum and cerebrospinal fluid (FSME IgM ELISA Immuno Austria). 12 patients (60%) reported a tick bite preceding the disease. Following clinical manifestations were found in the analyzed groups of patients: fever > 37.5 degrees C-20 patients (100%), headache--20 patients(100%), nuchal rigidity-14 patients (70%), abdominal pain -3 patients (15%), arthralgia and myalgia-3 patients (15%), drowsiness and mental confusion -3 patients(15%). Total cell count in CSF ranged from 18 to 348 cells (mean-175). Lymphocytes predominated in 13 cases (68%). The FSME-IgM antibodies were present in serum of 19 patients (95%) and in CSF of only 4 patients (20%). The hospitalization lasted 12-58 days (mean 24 days). In one case the disease was complicated by acute psychosis requiring psychiatric treatment. Severe neurologic complications have been not observed. The prognosis in all cases was good. Our study confirms that tick-borne encephalitis is a current problem in north-eastern Poland. Noteworthy is the fact that only a part of patients give the history of tick bite.

Adolescent↗
PubMed1996

Clostridium difficile colitis--diagnosis and therapy.

Clostridium difficile is a Gram-positive bacillus which had been identified as the source of potent exotoxins: toxin A and toxin B. C. difficile infection usually follows antibiotic therapy and results from unrestrained growth of pathogenic strains of C. difficile in the colon. Typical clinical findings include: diarrhoea with blood and mucus, fever, abdominal pain, nausea, loss of body weight. In the past the diagnosis was based on positive result of stool culture but now several tests are available: latex-agglutination test, enzyme immunoassays and fluorescence-immunoenzymatic tests. Diagnostic methods enable quick and safe detection of C. difficile antigens or toxins and proper management. Poor susceptibility of C. difficile strains to common antibiotics hinders choosing the effective therapy.

Clostridioides difficile↗
PubMed1995

Directional coronary atherectomy for lesions of the proximal left anterior descending artery: initial clinical results, complications and histopathological findings.

BACKGROUND: Directional coronary atherectomy is a percutaneous technique which extends the role of balloon angioplasty to bulky eccentric coronary lesions. AIMS: To report the early experience, clinical results, complications and histopathological findings of directional coronary atherectomy (DCA) in proximal left anterior descending artery (LAD) stenosis. METHODS: Study of 25 lesions in 24 patients on whom directional atherectomy was performed on the proximal LAD artery with the Simpson coronary atherectomy device. RESULTS: Twenty-five procedures were performed on 24 patients with stenosis in the proximal LAD artery. There were 21 males and three females with a mean age of 56.5 years. Sixteen patients presented with stable angina and eight with unstable angina. Eight patients had previous myocardial infarction (MI). Angiographic success was obtained in 24 of 25 lesions (96%). The mean lesion length was 13.1 +/- 3.7 mm and the mean LAD artery diameter was 3.6 +/- 0.5 mm. Minimal luminal diameter improved from 0.9 +/- 0.4 mm to 3.0 +/- 0.5 mm and the percentage diameter stenosis reduced from 75 +/- 12% to 16 +/- 9%. Complications included acute occlusion in one patient, non-Q MI in three patients, local vascular complications in one patient and side-branch loss in one patient. Histology demonstrated fibrous cap of atherosclerotic plaque in 100%, media and internal elastic lamina in 28% and intimal hyperplasia in 100% of restenotic lesions and 27% of native lesions. Restenosis rates in angiographically restudied patients was 27%. The mean minimal luminal diameter at follow-up was 2.3 +/- 0.9 mm and the mean percentage diameter stenosis was 35 +/- 21%. CONCLUSION: From this initial study, we conclude that DCA is an effective and safe procedure for the treatment of large proximal LAD lesions. DCA provides a large luminal diameter and "smoother' angiographic appearance compared to coronary angioplasty. Acute complication rates are low and restenosis rates were comparable with percutaneous transluminal coronary balloon angioplasty.

Adult↗
PubMed1995

[Occurrence and clinical picture of Clostridium difficile infections after antibiotic therapy].

39 patients with colon bowel inflammatory by C. difficile infection after antibioticotherapy were treated. The causes of antibioticotherapy most frequently former infection of the upper respiratory tract. The C. difficile infection were most frequently before therapy: poliantibiotics, Cephalosporins II generations and Linkomycin. In diagnosis of C. difficile infection the Enzyme Immuno-Fluorescence Test were practical utility confirmed. The symphtomaticotherapy patients with slight course of ills were sufficiently. The therapy of Metronidazol or/and Colestyramine in patients with mild or highly course of ills were efficacious.

Adult↗
PubMed1994

Limitation of panoramic radiography in diagnosing adenomatoid odontogenic tumors.

Adenomatoid odontogenic tumor is frequently not diagnosed preoperatively even when radiographs are available. This study evaluates radiographic findings with special emphasis on the characteristic radiopacities of adenomatoid odontogenic tumor. In correlating radiologic findings with pathologic findings, differences in diagnostic accuracy between intraoral periapical and panoramic radiographs were found. The intraoral periapical radiograph allows perception of the radiopacities in adenomatoid odontogenic tumor as discrete foci having a flocculent pattern within radiolucency even with minimal calcified deposits. Panoramic radiography was often unable to demonstrate radiopacities in adenomatoid odontogenic tumor when the calcification was minimal. The result indicates that intraoral radiographs may be essential for correct radiographic interpretation of an adenomatoid odontogenic tumor in the presence of minimal quantities of calcified deposits.

Adolescent↗
PubMed1993

Computerised tomography does not predict N2 disease in patients with lung cancer.

BACKGROUND: Mediastinal node involvement in primary lung cancer determines the staging and prognosis of the patient, and as these nodes can be seen on the computerised tomography (CT) scan of the chest it is a temptation to diagnose malignant involvement if the nodes appear enlarged. However, initial experience with mediastinal node mapping at lung resection demonstrated this extrapolation to be unreliable and misinterpretation of enlarged nodes on CT may lead to misdiagnosis and prejudice the patient's management. AIM: To demonstrate that the sensitivity, specificity, and accuracy of the CT to detect malignant mediastinal nodes is too low to use size of node on CT as representative of malignant involvement. METHODS: One hundred and fifty-three sequential patients with resectable lung cancer were studied with preoperative CT. Two radiologists determined the preoperative T and N status from these studies with nodes of 1.5 cm or larger diagnosed abnormal. These results were compared to the results of subsequent node mapping performed after lung resection. RESULTS: Sensitivity was found to be 26%, specificity to be 81% and overall accuracy 69%--too low to justify the diagnosis of N2 disease on size of 1.5 cm or larger. CT is not a valid means of diagnosing malignant involvement of mediastinal nodes.

Humans↗