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Biomedical subjects

C Hammer

Publications and source records attributed to C Hammer.

At least 199 records · Page 11Linked to original sources
PubMed1988

Quantification of age pigments (lipofuscin).

1. Three methods have hitherto been applied for age pigment quantification: (a) numerically from micrographs; (b) fluorimetrically from histological sections; (c) spectrofluorimetrically from dissolved age pigments. 2. The spectrofluorimetric method is at present the most commonly used technique for quantification of age pigments. 3. By comparing the related publications since introduction of the spectrofluorimetric method, it has become apparent that few authors specify fluorimetrically significant factors, such as temperature and pH which influence the sample fluorescence during measurement. 4. Recent developments in fluorimetrical age pigment quantification using chloroform/methanol as solvent have additionally revealed the necessity to measure and present the age pigments dissolved in both phases: the polar and non-polar solvents.

Aging↗
PubMed1988

Application of a fibrinogen-thrombin-collagen-based hemostyptic agent in experimental injuries of liver and spleen.

FTCH is a recently developed material which consists of a collagen fleece containing fibrinogen, thrombin, and aprotinin integrated into its surface. FTCH is highly effective in sealing of tissues and in establishing hemostasis. We evaluated FTCH in experimentally produced liver (n = 6) and splenic (n = 12) injuries in 18 adult mongrel dogs. The stability of the parenchymal seal of the splenic injuries was tested by splenic tissue pressure elevation after temporary ligation of the splenic vein. No breakthrough bleeding occurred up to a parenchymal pressure of 16.3 +/- 5 mm Hg. Complete hemostasis was easily achieved in all animals before closure. When the dogs were re-explored postoperatively at intervals of either 14 or 30 days, there was no gross evidence of recurrent bleeding. Histologic examinations demonstrated a partially regenerated capsule covering an unspecific fibrovascular granulation tissue and progressive resorption of FTCH without significant inflammatory response. We conclude the following: FTCH provides adequate hemostatic control of experimental liver and splenic injuries. FTCH has excellent tissue compatibility and can be applied easily and safely to hemorrhaging parenchymal wounds. It will not replace adequate surgical techniques, but could be useful as a quickly available and easily applicable hemostatic means in diffuse or acute bleeding of liver and spleen.

Animals↗
PubMed1988

New methods for noninvasive monitoring of rejection after heart transplantation.

Between August 1981 and February 1987, 67 orthotopic heart transplants and three heart-lung transplants were performed in 69 patients at the University of Munich Hospital. The immunosuppressive regimen consisted of cyclosporine A, azathioprine, and prednisone. The diagnosis of acute rejection was based on cytoimmunologic monitoring, frequency analysis of fast Fourier transformed surface electrocardiograms (FFT-ECGs), and two-dimensional echocardiography. The results of these diagnostic methods were compared to the findings provided by endomyocardial biopsies, which were performed simultaneously with the noninvasive studies. Seventy patients underwent cytoimmunologic monitoring. In 88% of all rejection episodes, this technique revealed activated lymphocytes and lymphoblasts in the mononuclear concentrate of the peripheral blood samples; the presence of such cells is known to be an extremely early sign of acute rejection. Twenty-six patients were monitored by means of FFT-ECG. In 20 of the 21 cases of rejection, this method disclosed significant changes in the frequency spectrum of the QRS complex in the 70- to 110-Hz range; in 12 cases, these changes were the earliest sign of acute rejection. Therefore, FFT-ECG had a sensitivity of 95%. All of the QRS changes were reversible with rejection therapy. Forty-five patients were subjected to two-dimensional echocardiography. In 31 of the 35 cases of rejection, the echocardiogram showed a significant increase in the left ventricular wall thickness and a decrease in the left ventricular cross-sectional area during mild rejection. Moderate or severe rejection was characterized by an increase in the diastolic area, as well as a decrease in the systolic area change and in the diastolic maximum velocity of area change. Thus, two-dimensional echocardiography had a sensitivity of 89%. In the recent cases, the diagnosis of rejection was based on noninvasive methods alone. After rejection therapy had been instituted, endomyocardial biopsies were performed to assess the effectiveness of the treatment. With noninvasive rejection monitoring, the number of endomyocardial biopsies performed during the first three postoperative months was only 2.8 per patient; in comparison with invasive rejection monitoring, noninvasive follow-up was associated with a 75% reduction in the need for biopsy.

Journal Article↗
PubMed1987

The effectiveness of a fibrinogen-thrombin-collagen-based hemostatic agent in an experimental arterial bleeding model.

The hemostyptic agent used in this study is a recently developed material that consists of a collagen fleece containing fibrinogen, thrombin, and aprotinin integrated into its surface (FTCH) with excellent topical hemostyptic properties. The potential use of this substance for cardiovascular surgery was evaluated in a canine arterial bleeding model, which allowed comparison of the new agent with previously used pure collagen (CHF) as well as study of the hemostyptic under elevated blood pressure conditions. The results revealed that FTCH induced reliable hemostasis in 10-mm injuries of the canine hypogastric artery up to a systolic blood pressure of 260 mmHg, whereas bleeding control by CHF alone was impossible. To assess the long-term reliability of FTCH, the dogs were re-explored at intervals of 14 and 31 days after operation. At relaparotomy, the arteries were patent and there was no evidence of recurrent bleeding, thrombosis formation, or aneurysmatic changes. Histologic examinations showed well-healed vascular lesions covered by cell-depleted collagen tissue and a partially resorped hemostyptic. FTCH will not replace adequate surgical techniques but could be useful as a quickly available and easily applicable hemostatic means in otherwise uncontrollable diffuse or acute bleeding in cardiovascular surgery.

Animals↗
PubMed1987

[Immunological studies on patients with tonsillar carcinoma: progress?].

Of 101 consecutive cases of tonsillar carcinoma, 76 were finally selected as fulfilling the statistical requirement of the study. 25 of the cases were excluded because of deficiency of follow-up information. Actuarial survival time up to five years was compared with tumor staging and grading as well as with immunological parameters measured. Autologous and allogeneic anti-tumor antibodies were used for diagnostic purposes. Lymphocyte subpopulations, their distinction and in vitro function as suppressor cells was measured during the course of the disease. Actuarial five years survival time was 55%. Males contributed with 76% of the patients usually showing more progressed disease than females. Antibodies directed against tumor cells were found in all patients but not in healthy volunteers. A mean of 15% of immunofluorescence positive tumor cells revealed the best sensitivity, specificity and progressive value in terms of recurrencies. 5.8 months after reappearance of positive cells in the former operation area recurrencies could be proven histologically. 6.8 months later on the patients had died. Neither course of disease nor staging or grading of tumors showed a significant influence on lymphocyte subpopulations. In later stages in less differentiated tumors T-suppressor phenotypes showed an increase in numbers as compared to T-helper-cells. In parallel a significant rise of in-vitro suppressor activity of peripheral and lymph node lymphocytes could be detected. It is suggested that the rather good survival time is due to an intensive postoperative care and multiple hints from various immunological tests in addition to clinical signs. They allow to intensify directly the therapeutic and hygienic measures needed.

Adult↗