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Biomedical subjects

J Albers

Publications and source records attributed to J Albers.

At least 37 records · Page 2Linked to original sources
PubMed1998

Heterogeneity of myocardial edema in isolated pig hearts after perfusion with different types of cardioprotective solutions.

The extent and distribution of myocardial edema induced by perfusion with cardioprotective solutions is of great interest. Domestic pig hearts (n = 12) were perfused in situ after aortic cross clamping either with Bretschneider's cardioplegic solution (HTK, 4 degrees C, n = 3), with a heparinized Krebs-Henseleit solution containing 30 mmol/L 2,3 Butanedionemonoxime (BDM, 4 degrees C, n = 3) or with heparinized pig blood (HPB, 24 degrees C, n = 3). After a three-hours storage period, magnetic resonance tomography (MRI) was carried out. The acquired T1-weighted data were used for the subsequent three-dimensional reconstruction based on the "Heidelberg ray-tracing technique". The small myocardial tissue blocks (n = 216) were excised from these hearts for dry weight measurements for 9 preselected regions in duplicate including ventricular papillary muscle, ventricular free wall, ventricular septum, apex, and atrial tissue. In control hearts (n = 3), dry weight was measured immediately after explantation (no MRI). The results of dry-weight measurements and three dimensional visualization were compared. Dry-weight measurements revealed that considerable myocardial edema is induced by any of the experimental procedures. The effects were most pronounced after BDM perfusion. Regardless how the edema was induced, there were significant differences of the water content within the heart: the water content in the heads of the papillary muscles and in the interventricular septum was always smaller than that of the free left- and right-ventricular walls. The heterogeneity of myocardial edema and its spatial distribution pattern could be qualitatively visualized. The experimental data (biophysical data and 3D visualization) clearly show a heterogeneity of myocardial edema induced by different types of cardioprotective solutions. As the presence of myocardial edema represents one of the crucial events in the pathophysiology of myocardial dysfunction occurring during myocardial infarction, ischemia, heart transplantation, and extracorporeal circulation, the present study represents an interesting contribution towards intravital detection and distribution of myocardial edema.

Animals↗
PubMed1998

A case of respiratory muscle weakness due to cytochrome c oxidase enzyme deficiency.

Mitochondrial myopathy is a rare cause of dyspnoea and respiratory failure, usually presenting in infancy. We describe a 27 yr old woman with a partial cytochrome c oxidase enzyme deficiency causing respiratory muscle weakness and respiratory failure. The onset was acute, with no preceding respiratory symptoms. The patient was successfully treated with bilevel positive airway pressure therapy.

Adult↗
PubMed1998

Lipid altering or antioxidant vitamins for patients with coronary disease and very low HDL cholesterol? The HDL-Atherosclerosis Treatment Study Design.

Evidence supports the idea that substantial benefits may derive from treatments that increase high density lipoprotein (HDL) cholesterol (HDL-C), apolipoprotein (apo) A-I, HDL2 (or 2b) or the size of HDL particles with, or without, apo A-II. HDL3 appears to be neutral in terms of coronary artery disease risk, and apo A-II appears to be adverse. Because HDL particles serve as antioxidants in vitro, the hypothesis that low HDL-C reflects an antioxidant deficiency state appears tenable. Based on these observations, a three-year angiographic study was proposed and received funding. Enrollment began in January 1995 and was completed in January 1997.

Adult↗
PubMed1997

A mathematical high time resolution model of the arterial system under extracorporeal circulation.

OBJECTIVE: The purpose of the following study was to establish a computer-generated model of the hemodynamic effects of pulsatile extracorporal perfusion describing flow and pressure parameters in the body for any given input flow patterns. METHODS: The human arterial tree was delineated according to a 128-branch model encompassing bifurcations and linear physical properties of the arterial walls. The distribution of flow and pressure waves was calculated based on a refined 3-element windkessel model. Autoregulatory mechanisms of brain and kidneys were implemented. RESULTS: By providing a simulated, "pump-generated" flow curve as the input signal to the system, the model was able to create and display flow and pressure curves at a high time resolution in each part of the systemic circulation including reflection phenomena throughout any observation period chosen. The hemodynamic effects of different pump-flow patterns, age, variations in hematocrit, hypothermia and occlusion of arterial branches, like the renal artery, could be simulated. CONCLUSION: In an attempt to get closer to a mathematically based regulation of heart-lung machines, this model of computer generated extracorporeal circulation provides an initial step. Ongoing research is required for implementation of metabolic conditions and continuous approximation of the model of the real physiologic or pathologic situation.

Arteries↗
PubMed1996

Tumor proliferative activity is predictive of pathological stage in clinical stage A nonseminomatous testicular germ cell tumors.

PURPOSE: Traditional histopathological features have failed to predict accurately the pathological stage of clinical stage A nonseminomatous germ cell tumors of the testis. Based on pilot studies in nonconsecutive patients at our university, we evaluated nontraditional risk factors (cell cycle analysis by flow cytometry, deoxyribonucleic acid analysis by single cell cytophotometry [image analysis] and assessment of proliferative activity by immunohistochemistry) combined with histopathological features in consecutive patients with clinical stage A nonseminomatous testis cancer. MATERIALS AND METHODS: Orchiectomy specimens from 105 consecutive patients with clinical stage A nonseminomatous germ cell tumors who underwent retroperitoneal lymph node dissection (76 with pathological stage A disease and 29 with proved metastasis) were recut, histopathologically reviewed, immunohistochemically stained with proliferation markers (for example Ki-67/MIB-1), and examined by flow cytometry and image analysis. RESULTS: After multiple logistic regression analysis, the G2M+S cell cycle fraction of the aneuploid tumor stemline was the most predictive parameter of pathological stage (p = 0.0004). Using a cutoff of 41%, patients with metastasis were predicted with a sensitivity of 71%. Of 61 patients with a G2M+S value of less than 41%, 53 had pathological stage A cancer (negative predictive value 87%). A low volume of embryonal carcinoma was predominant in patients at low risk for metastasis and MIB-1 immunohistochemical staining identified 23% of patients with pathological stage A tumor who were at extremely low risk for metastatic disease. CONCLUSIONS: Assessment of tumor cell proliferation cannot classify accurately high risk patients at a clinically applicable level. However, identification of patients at low risk for metastasis by flow cytometry, immunohistochemical proliferation markers and volume of embryonal carcinoma may be possible at the 90% level. MIB-1 staining is able to classify patients at extremely low risk for metastasis. These parameters deserve further study, since identification of patients at extremely low risk for metastasis could potentially decrease overall morbidity in the management of clinical stage A nonseminomatous testis cancer.

Cell Division↗
PubMed1995

Immunohistochemical assessment of tumor proliferation and volume of embryonal carcinoma identify patients with clinical stage A nonseminomatous testicular germ cell tumor at low risk for occult metastasis.

BACKGROUND: Thirty percent of patients with clinical Stage A nonseminomatous testicular germ cell tumor (NSGCT) are incorrectly clinically staged. In a previous retrospective study at Indiana University, the combination of tumor proliferation rates by flow cytometry and histopathologic evaluation defined risk groups for occult metastatic disease in these patients with clinical Stage A NSGCT: A new immunohistochemical proliferation marker (MIB-1) was therefore used to assess growth fraction in combination with histopathology in an effort to predict pathologic stage in patients with clinical Stage A NSGCT: METHODS: Primary orchiectomy specimens from 90 consecutive patients with clinical Stage A NSGCT (January 1992-November 1993) who underwent retroperitoneal lymph node dissection at Indiana University were histopathologically evaluated. Formalin fixed, paraffin embedded tissue sections were immunohistochemically stained using a monoclonal antibody against the nuclear proliferation-associated antigen Ki-67 (MIB-1). Satisfactory staining was obtained by using an antigen retrieval method based on microwave oven heating of paraffin sections. RESULTS: MIB-1 immunohistochemical staining showed significant differences in mean values between 65 patients (66.1%) with pathologic Stage A NSGCT and 25 (80.4%) patients with pathologic Stage B NSGCT (P = 0.0032). The negative predictive value for patients with pathologic Stage A disease was 87% using a cut-off of 80% or less MIB-1 positively stained cells. A combined approach, using the absolute volume of embryonal carcinoma per patient (< 2 ml) and MIB-1 immunostaining (< or = 80%) was able to define a group of 30% of all patients who were at extremely low risk for occult metastatic disease. CONCLUSIONS: MIB-1 immunostaining in combination with histopathology aided in defining a low risk group patients with clinical Stage A NSGCT but failed to identify patients at high risk for metastasis. The risk factors need to be tested in a prospective clinical trial to determine if they are potentially useful in assigning therapy to individual patients.

Antigens, Neoplasm↗
PubMed1995

[New parameters for prediction of pathological stage in clinical stage I non-seminomatous testicular tumors].

Traditional histopathological risk factors have failed to predict pathological stage accurately in clinical stage I nonseminomatous testicular germ cell tumours. Histopathology, flow cytometry, cytophotometry, and immunohistochemical staining techniques were used in an effort to define high- and low-risk groups for occult metastasis in a consecutive series of 105 patients who underwent retroperitoneal lymph node dissection. After multiple logistic regression analysis, the proliferative S + G2M cell cycle fraction of the aneuploid tumour stemline was the most highly predictive parameter of pathological stage (P = 0.0004). Using a cut-off of 41%, pathological stage II patients were predicted with a sensitivity of 71%. There were 61 patients with S + G2M values below 41%, and 43 of them had pathological stage I disease (negative predictive value 87%). A low volume of embryonal carcinoma was predominant in low-risk patients, and MIB-1 immunohistochemical staining identified a subgroup of 23% of patients with pathological stage I disease and at extremely low risk of metastatic disease. Assessment of tumour cell proliferation does not allow accurate classification of high-risk patients at a level that is adequate for clinical application. Patients who are at low risk of metastasis, however, can be identified by flow cytometry, immunohistochemical proliferation markers and volume of embryonal carcinoma with 90% certainty. These parameters deserve further study, since identification of a subgroup of patients at extremely low risk of metastasis could potentially reduce the overall morbidity in the management of clinical stage I nonseminomatous testis cancer.

Animals↗
PubMed1993

Differences of size and shape of active and inactive X-chromosome domains in human amniotic fluid cell nuclei.

It is a widely held belief that the inactive X-chromosome (Xi) in female cell nuclei is strongly condensed as compared to the largely decondensed active X-chromosome (Xa). We have reconsidered this problem and painted X-chromosome domains in nuclei of subconfluent, female and male human amniotic fluid cell cultures (46,XX and 46,XY) by chromosomal in situ suppression (CISS) hybridization with biotinylated human X-chromosome specific library DNA. FITC-conjugated avidin was used for probe detection and nuclei were counterstained with propidium iodide (PI). The shape of these nuclei resembling flat ellipsoids or elliptical cylinders makes them suitable for both two-dimensional (2D) and three-dimensional (3D) analyses. 2D analyses of Xi- and Xa-domains were performed in 34 female cell nuclei by outlining of the painted domains using a camera lucida. Identification of the sex chromatin body in DAPI-stained nuclei prior to CISS-hybridization was confirmed by its colocalization with one of the two painted X-domains. In 31 of the 34 nuclei the area AXi for the inactive X-domain was smaller than the area AXa for the active domain (mean ratio AXa/AXi = 1.9 +/- 0.8 SD, range 1.0-4.3). The signed rank test showed a highly significant (P < .0001) difference both between AXa and AXi and between the ratios r(Xa) and r(Xi), calculated by dividing the maximum length L of each X-domain by its maximum width W. In most nuclei (26/34) we found r(Xa) > r(Xi) demonstrating a generally more elongated structure of Xa. For 3D analysis a confocal scanning laser fluorescence microscope (CSLFM) was used. Ten to 20 light optical sections (PI-image, FITC-image) were registered with equal spacings (approx. 0.4 microns). A thresholding procedure was applied to determine the PI-labeled nuclear and FITC-labeled X-domain areas in each section. Estimated slice volumes were used to compute total nuclear and X-domain volumes. In a series of 35 female nuclei most domains extended from the top to the bottom nuclear sections. The larger of the two X-chromosome domains comprised (3.7 +/- 1.7 S.D.)% of the nuclear volume. A mean ratio of 1.2 +/- 0.2 SD (range 1.1-2.3) was found for the volumes of the larger and the smaller X-domains in these female nuclei. In a series of 27 male amniotic fluid cell nuclei the relative X-chromosome domain volume comprised (4.0 +/- 2.6 S.D.)%.(ABSTRACT TRUNCATED AT 400 WORDS)

Amniotic Fluid↗