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Biomedical subjects

C Homann

Publications and source records attributed to C Homann.

14 recordsLinked to original sources
PubMed2000

[Experimental and finite-element models for the assessment of mandibular deformation under mechanical loading].

Biomechanical investigations of the mandible are difficult to perform due to a variety of conditions involved. For the appropriate reconstruction of biomechanical properties, a geometrically correct body model has to be established which fits to complex in vivo conditions. The aim of our study was to evaluate the use of finite-element models (FEM) for the assessment of mandibular deformation under mechanical loading. Explanted human mandibles (n = 5) were investigated by strain gauges to determine the individual strain distribution under mechanical loading. FEM analysis based on a computed tomograph (CT) was performed and the results were matched with the test data. Our study demonstrates only minor interindividual differences in the strain distribution for each load studied. The mechanical response in terms of deformation was found to depend mainly on gross geometrical properties and to a minor extent on the various other variables. At all positions the maximum principal strain was tensile, the minimum principal strain was compressive, and the absolute strain values were correlated with the magnitude of the applied force. CT-based FEM analysis revealed the utility of mathematical models to approximate simulated data our experimental results. Hence, FEM analysis is a non-invasive tool in the prediction of biomechanical behaviour of individual mandibles and therefore may help in trauma reconstruction and treatment planning.

Biomechanical Phenomena↗
PubMed1998

Mannan binding lectin in rheumatoid arthritis. A longitudinal study.

OBJECTIVE: Low serum levels of mannan binding lectin (MBL) are associated with increased risk of recurrent infections. We determined whether there was an association between serum MBL levels and the course and prognosis of rheumatoid arthritis (RA). METHODS: MBL was analyzed in sera from 99 patients with RA who were included in a longterm prospective study. RESULTS: Compared with controls, a high fraction of patients lacked detectable MBL in serum (11 vs 3%; p = 0.025). Comparing patients with MBL serum levels above and below the median revealed that those with levels below the median were younger at onset of RA (p = 0.043) and had higher erythrocyte sedimentation rate (p = 0.006), joint swelling score (p = 0.019), limitation of joint motion score (p = 0.027), and annual increase in radiographic destruction score (p = 0.053). CONCLUSION: MBL insufficiency may be a contributing pathogenetic factor in RA.

Adolescent↗
PubMed1997

[Intestinal tuberculosis].

Since the symptoms and clinical presentation of intestinal tuberculosis is nonspecific, the diagnosis is frequently delayed and may be achieved at autopsy only. Intestinal tuberculosis is very rare in Denmark, but may now be seen more often because of increasing numbers of immigrants from countries of the third world with a high prevalence of tuberculosis. A case of intestinal tuberculosis in a 28 year old Somalian female is reported. Methods of diagnosing intestinal tuberculosis are commented, and the frequent necessity of starting medical treatment before a bacteriological diagnosis is reached is emphasized.

Adult↗
PubMed1997

Acquired C3 deficiency in patients with alcoholic cirrhosis predisposes to infection and increased mortality.

BACKGROUND: Acquired deficiencies of certain complement proteins and impaired opsonisation activity have been implicated in the pathogenesis of the increased susceptibility to infections of patients with alcoholic cirrhosis. METHODS: Serum concentrations of C3 and C4, plasma concentrations of C3bc, C9, and the terminal C5b-9 complement complex (TCC), and haemolytic complement activity (classic and alternative pathway) of serum, and serum opsonic activity were determined in 46 patients with compensated alcoholic cirrhosis, 31 who were decompensated, and in 15 healthy subjects. After 19 months (median) the investigated variables were analysed for their use in prognosis of recurrent infections and survival. RESULTS: C3 and C4 concentrations and the haemolytic complement activity of the alternative pathway were decreased in decompensated cirrhotic patients compared with controls (p < 0.01). Univariate analysis (log rank test) showed that low concentrations (< or = lower quartile) of C3 (p < 0.001) and C3bc (p < 0.05), haemolytic complement activity of the alternative pathway (p < 0.01) and classic pathway (p < 0.05), and decompensated cirrhosis (p < 0.001) were associated with an increased risk of infection and increased mortality. Multivariate (Cox) analysis showed that low C3 concentrations and decompensation of cirrhosis were significant predictors of infections and mortality (p < 0.02). CONCLUSIONS: Low serum C3 concentrations and decreased haemolytic complement function predisposes to infection and increased mortality in patients with alcoholic cirrhosis.

Adult↗
PubMed1996

[Plasma calprotectin. A new prognostic marker of survival in alcoholic liver cirrhosis].

The purpose of this study was to determine plasma concentrations of calprotectin in patients with different severity of alcoholic cirrhosis. Additionally, the prognostic value of calprotectin for recurrent infections and for survival was investigated after a median observation period of 19 months. No difference was found in calprotectin levels when comparing healthy controls (n = 16), compensated (n = 50) and decompensated cirrhotics (n = 34). However, high calprotectin concentrations (> median) was a significant prognostic marker of poor survival (p = 0.001, Log-rank test). Calprotectin levels (> median) showed an independent and much higher prognostic value than variables of liver disease (multivariate Cox model). During follow-up calprotectin levels (> median) were also a predictor of recurrent infection (p = 0.009, Log-rank test). Thus, in patients with alcoholic cirrhosis, plasma calprotectin appears to be a new prognostic marker of survival, which seems independent of severity of liver disease. Furthermore, high plasma calprotectin levels may characterize a group of cirrhotics with recurring bacterial infections.

Adult↗
PubMed1996

Anti-interleukin-6 autoantibodies in plasma are associated with an increased frequency of infections and increased mortality of patients with alcoholic cirrhosis.

Altered cytokine metabolism has been implicated in the pathogenesis of alcoholic liver disease. Recently, autoantibodies to cytokines have been proposed to act as modifiers of cytokine functions. In this study plasma levels of anti-interleukin-1 alpha (IL-1 alpha autoantibodies and anti-IL-6 autoantibodies were determined by RIAs in 96 patients with alcoholic cirrhosis and in 16 healthy individuals. After 19 months (median) the prognostic significance of the cytokine autoantibodies was investigated using univariate analysis (Log-rank test) and multivariate regression analysis (Cox model). The seroprevalences of anti-IL-1 alpha autoantibodies and anti-IL-6 autoantibodies (42 and 18%, respectively) in the patients were not different from healthy individuals and did not relate to severity of liver disease. The presence of anti-IL-1 alpha autoantibodies was of no prognostic significance. Independent of severity of liver disease, patients with anti-IL-6 autoantibodies in plasma had a higher risk of acquiring infections and higher risk of death (P < 0.02) compared to patients without anti-IL-6 autoantibodies. The authors concluded that anti-IL-6 autoantibodies are associated with increased mortality when present in the plasma of patients with alcoholic cirrhosis, which is probably secondary to recurrent infections, but not to underlying severity of liver disease.

Adult↗
PubMed1996

Serum clusterin and vitronectin in alcoholic cirrhosis.

Clusterin and vitronectin are multifunctional regulatory proteins which both serve as complement lysis inhibitors. Previous data have strongly suggested that serum vitronectin is mainly produced in the liver, whereas the biosynthetic origin for serum clusterin has not been determined. In the present study we aimed to determine the role of the liver in producing these proteins and to evaluate the proteins as possible markers of liver failure. We therefore quantified clusterin and vitronectin in serum from patients suffering from alcoholic liver cirrhosis (n = 83), and in serum-free culture supernatants from the hepatoma cell line HepG2. The median clusterin concentration was 0.20 g/l in cirrhosis and 0.37 g/l in the controls, whereas corresponding vitronectin values were 0.19 and 0.26 g/l, respectively. The concentration of both proteins showed significant correlation (p < 0.0001) with disease severity and with established plasma markers of hepatic synthetic function, such as albumin and prothrombin complex. The clusterin level, but not the vitronectin level, correlated with survival (p = 0.005). The rates of synthesis of clusterin, vitronectin and C3 from HepG2 cells were 0.02, 0.21 and 1.9 micrograms/10(6) cells/24 h, respectively. From the present data we conclude that clusterin (as vitronectin and C3) is mainly produced in the liver and may be a useful marker in the evaluation of severity of liver disease and prognosis of patients with alcoholic cirrhosis.

Adult↗
PubMed1995

Mannan-binding protein and complement dependent opsonization in alcoholic cirrhosis.

Mannan-binding protein is synthesized by the liver and functions in first-line host defence by opsonizing mannose-rich microorganisms due to activation of the classical complement pathway independent of Clq, and by an intrinsic ability to opsonize and mediate phagocytosis. We have investigated whether the increased susceptibility to bacterial infections in patients with cirrhosis could be explained by low plasma concentrations of mannan-binding protein and impaired complement-dependent opsonization. We examined 51 patients with compensated alcoholic cirrhosis, 34 who were decompensated and 16 healthy controls. Irrespective of group, we found a significant correlation (p < 0.05) between plasma mannan-binding protein concentration and deposition of the complement opsonin C4 on mannan from baker's yeast. In contrast to what was expected, this kind of opsonization and plasma levels of mannan-binding protein were significantly increased in the patients with decompensated cirrhosis (p = 0.01 and p = 0.007, respectively). A significant correlation (0 < 0.05) was found between mannan-binding protein and erythrocyte sedimentation rate, fibrinogen and haptoglobin in these patients. Though the correlations were weak (rho = 0.49, rho = 0.48 and rho = 0.40, respectively), the elevated levels of mannan-binding protein in the patients with decompensated cirrhosis may reflect an acute phase reaction. It is concluded that plasma levels of mannan-binding protein are increased in patients with decompensated cirrhosis and that complement-dependent opsonization of mannan does not seem to be compromized in patients with alcoholic cirrhosis.

Adult↗
PubMed1995

Plasma calprotectin: a new prognostic marker of survival in alcohol-induced cirrhosis.

Plasma levels of calprotectin were determined in 84 patients with alcohol-induced cirrhosis. Calprotectin is released from disintegrating neutrophils, and plasma levels seem to reflect activation and turnover of such cells. The purpose of the study was to investigate the degree of activation of neutrophils, which has been indicated to be increased and a cause of neutrophil exhaustion in these patients. Additionally, on follow-up after a median observation period of 559 days, we investigated the prognostic value of calprotectin for survival. No difference was found in calprotectin levels when comparing healthy controls with patients with compensated cirrhosis and those with decompensated cirrhosis. However, high calprotectin concentrations (> median) were a significant prognostic marker of poor survival (P = .001, log-rank test). Using a multivariate Cox proportional hazard model, the prognostic value of calprotectin seemed independent of severity of liver disease evaluated on eight clinical and biochemical variables of liver disease. Divided into groups by the median calprotectin concentration, analysis of survival was performed in the whole series of patients (n = 84) as well as in patients who were completely without signs of recent or actual infection (n = 54). In both groups, calprotectin levels (> median) showed a much higher prognostic value than albumin, prothrombin complex, bilirubin, and ascites. During follow-up, calprotectin levels (> median) were also a predictor of recurrent infection (P = .009). Thus, in patients with alcoholic cirrhosis, plasma calprotectin seems to be a new prognostic marker of survival, which seems independent of the severity of liver disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Sex hormone binding globulin phenotypes: their detection and distribution in healthy adults and in different clinical conditions.

Human sex hormone binding globulin (SHBG) is encoded by a normal and a variant allele. The resulting SHBG phenotypes (the homozygous normal SHBG, the heterozygous SHBG and the homozygous variant SHBG phenotype) can be distinguished by their electrophoretic patterns. We developed a novel detection system allowing us to distinguish between the different electrophoretic patterns in small amounts of plasma or serum (10 microliters). Small aliquots of Blue Sepharose were added to diluted sera or plasma samples for removal of albumin and the supernatants were subsequently applied to Western blotting. This method of detection was used to determine the distribution of SHBG phenotypes in healthy controls of both sexes and in five different pathological conditions characterized by changes in the SHBG level or endocrine disturbances (malignant and benign ovarian neoplasms, hirsutism, liver cirrhosis and alcoholism). The distribution of SHBG phenotypes was independent of such conditions and in agreement with the expected phenotype distribution of a bi-allelic gene in both healthy controls and patients (Hardy Weinberg law). An allele frequency of 0.13 was found for the SHBG variant allele based on the experimental values. Differences in SHBG phenotypes do not appear to have any clinical significance and no sex difference was found in the SHBG phenotype distribution.

Adolescent↗
PubMed1992

[Hematological abnormalities in alcoholism].

The most common haematological abnormalities in alcoholism are raised mean corpuscular volume of the erythrocytes and thrombocytopenia. The etiology is multifactorial including malnutrition with folate deficiency, a direct toxic influence of alcohol and sequestration in an enlarged spleen. Sideroblastic anaemia caused by interference of alcohol with the metabolism of pyridoxine is common and so is haemolytic anaemia caused by hypersplenism and megaloblastic anaemia. Leucopenia can be seen and is probably caused by a direct toxic effect of alcohol on the bone marrow. Other potentially toxic changes are impaired chemotaxis, motility and adherence of the granulocytes and impaired blast-transformation of the lymphocytes. In the bone marrow, vacuolized precursors of myelo- and erythropoiesis are seen. The bone marrow may be hypocellular. Other changes in the bone marrow are increased but ineffective erythropoiesis with defective iron metabolism, vacuolized pro-erythroblasts, multinucleated erythroblasts, megaloblasts and iron-containing plasma cells.

Adult↗
PubMed1991

High incidence of hepatitis B infection and evolution of chronic hepatitis B infection in patients with advanced HIV infection.

Two hundred eleven HIV-seropositive patients with AIDS, AIDS-related complex, or a CD4+ cell count less than 200 x 10(6) were examined for the presence of hepatitis B virus markers during the course of their HIV infection (median follow-up of 18 months; range of 1 to 107 months). Anti-HBs was detected initially in 138 patients (65%). Sixteen patients (8%) were HBsAg positive at entry. Fourteen had chronic HBV infection of whom 12 initially were positive for HBeAg and HBV DNA; 11 remained positive during follow-up, whereas one seroconverted to anti-HBe and lost HBV DNA. Two patients with chronic HBV infection were initially negative for HBeAg and HBV DNA: one later had reactivated HBV replication and one cleared HBeAg following onset of hepatitis D infection. The last two HBsAg-positive patients had resolving acute HBV infection. Six of the 57 patients who initially were negative for HBV markers acquired HBV infection during follow-up. Four of these six patients developed chronic infection whereas two patients had acute subclinical resolving hepatitis. In addition, four patients became HBsAg positive with their last serum samples, possibly indicating reactivation of HBV infection following progressive immunological and clinical deterioration. None of the patients developed clinical symptoms that could be ascribed to HBV infection, and transaminase elevations were only sporadically recorded. It is concluded that acquisition of HBV infections is not infrequent in HIV-seropositive patients with immune deficiency. Furthermore, the course of both previously established chronic HBV infection and newly acquired HBV infection is modified in such patients, whereas reactivation of past HBV infection seems to be a rare event.

Adult↗