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Biomedical subjects

K Ritter

Publications and source records attributed to K Ritter.

At least 37 records · Page 2Linked to original sources
PubMed2000

The treatment of pseudoarthrosis of the scaphoid by bone grafting and three methods of internal fixation.

OBJECTIVES: To measure the rate of union in patients with pseudoarthosis of the scaphoid, treated with trapezoidal bone grafting as outlined by Fernandez and 1 of 3 methods of internal fixation and to compare unions versus nonunions and potential predictors of union to determine if associations exist. DESIGN: A retrospective radiologic study of scaphoid pseudoarthroses. SETTING: Division of Orthopedic Surgery, Ottawa Hospital, General Site, a tertiary care facility. PATIENTS: Thirty-four patients with nonunion of scaphoid fractures, treated between 1990 and 1997, with an average follow-up of 19.8 months. INTERVENTIONS: Trapezoidal bone grafting and internal fixation with Kirschner (K) wires, an AO cannulated screw or a Herbert screw. OUTCOME MEASURES: The time to union of scaphoid pseudoarthroses and predictors of union, including the classification, location of pseudoarthrosis, type of internal fixation and length of bone graft. RESULTS: The results showed a correlation between the classification and location of the fracture as determined radiologically, and the outcome. There was no correlation between the type of internal fixation used and the outcome, or between the length of the bone graft and the outcome. Twenty-three patients had radiologically demonstrated union after a mean time of 8.2 months; 16 of 24 patients achieved successful union when treated with K-wire implants, after a mean time of 7.2 months. CONCLUSIONS: Trapezoidal bone grafting and internal fixation with K wires is a practical technique, classification and location of the fracture notwithstanding. Time to union is long, and the results may be unpredictable. Use of K wires for internal fixation presents the clinician with an alternative to fixation with either the AO cannulated screw or the Herbert screw, and has the advantages of cost, ease of insertion and accessibility. This method may therefore be the treatment of choice in developing countries. Resection of the area of pseudoarthrosis must include all fibrous tissue and sclerotic bone. The length of graft, within the parameters of this study, did not affect the outcome.

Accidental Falls↗
PubMed2000

Fifty years of prison suicide in Austria: does legislation have an impact?

The absolute and relative frequency of suicides in jails and prisons in Austria over the 50 years from 1947 to 1996 is described. Important legislational changes regarding the criminal justice system are discussed with regard to possible consequences for the incidence of prisoners' suicides. Within the five decades a significant increase in the absolute numbers of jail and prison suicides was evident in spite of the considerable decrease in the total inmate population. Therefore, the suicide rate of inmates of correctional facilities increased significantly. Possible reasons for this phenomenon are discussed in relation to changes of the criminal law.

Austria↗
PubMed2000

Prison suicides in Austria, 1975-1997.

Suicide prevention in custody is hampered by the lack of funds and professional staff. In order to evaluate the prison suicide phenomenon, a study was conducted evaluating all suicides that occurred in Austrian prisons between 1975 and 1997 (n = 220). In addition to evaluating the number of male versus female suicides, the preferred suicide methods were studied, as well as suicide risk of different circumstances of custody. Suicide rates of distinguishable, important subgroups of prisoners were calculated. The suicide rate for prisoners on remand was 236.0 per 100,000, and for offenders classified as mentally ill it was 205.4 per 100,000. That is about 8 times higher than the suicide rate in Austria's general population (1975-1997: 24.6 per 100,000). The suicide rate for sentenced offenders was 81.3 per 100,000, about twice the suicide rate in Austria's general male population. We recommend that psychologists or psychiatrists concentrate on the suicide prevention of high-risk offenders after screening the newly admitted offenders for their propensity to suicide.

Austria↗
PubMed2000

[Assessment of custodial suicide risk--jail and prison suicides in Austria 1975-1996].

OBJECTIVE: Although incarceration is a high-risk situation for suicide all over the world, hardly any results have been published concerning the situation of custodial suicide in German-speaking countries. METHODS: We investigated the case notes of all suicides occuring in Austrian prisons between 1975 and 1996 (n= 207). Beside an evaluation of gender and preferred methods of suicide the suicide risk of different circumstances of custody was studied. Suicide rates of distinguishable, important subgroups of prisoners were calculated using the official statistical data of the Ministry of Justice. RESULTS: The suicide rate for people on remand and offenders classified as mentally ill was 231/100,000 vs. 191/100,000, that was about eight times higher than the suicide rate in Austria's general population. The suicide rate for sentenced offenders was 80/100,000, about three times as high as the suicide rate in Austria's general population (1980-1990: 26.4/100,000). The suicide risk increased with the length of the announced sentence. CONCLUSIONS: The suicide rate in custody was highest for prisoners on remand and mentally ill offenders. Female offenders had a high suicide risk, too. The common assumption that the suicide risk in jails and prisons is highest shortly after admission should be confirmed based on better methodology or be reconsidered.

Age Factors↗
PubMed1999

A membrane-located glycosphingolipid of monocyte/granulocyte lineage cells induces growth arrest and triggers the lytic viral cycle in Epstein-Barr virus genome-positive Burkitt lymphoma lines.

Gangliosides are known to influence cell growth and differentiation. The neolacto series ganglioside IV3NeuAc-nLc4 (2-->3-sialosylparagloboside) is present in members of the monocyte/granulocyte lineage, but is not found in cells that belong to the lymphocyte lineage. In this study we demonstrated that IV3NeuAc-nLc4 inhibits the proliferation of Epstein-Barr virus (EBV) genome-positive Burkitt lymphoma cells of the lines Raji and P3HR-1K. IV3NeuAc-nLc4-induced growth inhibition is associated with an increase in G0/G1 phase cells and a reduced expression of CD21 and HLA-DR antigens on Raji cells. These data suggest that IV3NeuAc-nLc4 may affect differentiation of lymphoma cells. Additionally, the increased expression of viral mRNA species which are characteristic for the lytic viral cycle in the non-producer line Raji and the enhanced release of virions from the producer line P3HR-1K demonstrate that IV3NeuAc-nLc4 activates the replication of EBV. Growth inhibition and termination of the viral latency suggest that IV3NeuAc-nLc4 present in monocyte/granulocyte lineage cells may be an effector of the natural defense against EBV persistency and transformation.

Apoptosis↗
PubMed1999

Characterization of cytostatically active glycosphingolipids isolated from thioglycollate-elicited murine macrophages.

Two acidic glycosphingolipids (gangliosides) derived from mouse macrophage membranes and separated by thin-layer chromatography have a strong cytostatic effect on human and mouse tumor cells. The structure of the two gangliosides, named M phi G1 and M phi G2, was elucidated by application of physicochemical and immunochemical methods. Gas chromatography and mass spectrometry of M phi G1 and M phi G2 classified them as isomeric monosialogangliosides with ceramide moieties composed of sphingosine as the long-chain base, C16 and C18 fatty acids, respectively, and a lacto-tetraose backbone. For M phi G1, additional immunochemical findings led to the proposed structure IV3NeuAc-nLcOse4Cer. The immunochemical reactions of M phi G2 suggest a branched structure for the oligosaccharide moiety.

Animals↗
PubMed1998

[Manganese superoxide dismutase-inhibiting autoantibodies in cholestatic Epstein-Barr viral hepatitis].

HISTORY AND CLINICAL FINDINGS: A 21-year-old woman reported no serious previous illness. For 3 days before admission she had a fever, headache and joint pains. She had become progressively more jaundiced. Physical examination was normal except for enlarged liver and spleen, swollen lymph nodes and facial oedema. INVESTIGATIONS: GOT (30 U/l), GPT (33 U/l) and alkaline phosphatase (172 U/l) were slightly elevated. Serum bilirubin was raised to 12.4 mg/dl. The total white blood cell count was normal, but there were 45% atypical lymphocytes (activated T lymphocytes). Abdominal sonography and endoscopic retrograde cholangiopancreatography were unremarkable. Serology for hepatitis A, B and C as well as for antimitochondrial antibodies was negative, but there were specific IgM (1:640) and IgG antibodies (1:80) against Epstein-Barr virus (EBV) capsid antigen in the immunofluorescence test. DIAGNOSIS, TREATMENT AND COURSE: The EBV infection (infectious mononucleosis) was complicated by cholestatic hepatitis. High concentrations (1832 Göttingen units/ml) of enzyme-inhibiting autoantibodies against the antioxidative enzyme manganese-superoxide dismutase (MSD) were demonstrated. The autoantibodies reduced the antioxidative action of the enzyme by more than 70% and favoured the oxidative cell damage in vitro. After bed-rest for one week without further treatment the symptoms improved and the abnormal laboratory values, including the autoantibodies against MSD, regressed. CONCLUSION: Autoantibodies against MSD are formed during an acute infection with EBV. Their enzyme-inhibiting action promotes abnormalities of oxidative cell function and may thus be the cause of cholestatic hepatitis in this infection.

Adult↗
PubMed1998

The cortical somatotopic map and phantom phenomena in subjects with congenital limb atrophy and traumatic amputees with phantom limb pain.

The extent of the cortical somatotopic map and its relationship to phantom phenomena was tested in five subjects with congenital absence of an upper limb, four traumatic amputees with phantom limb pain and five healthy controls. Cortical maps of the first and fifth digit of the intact hand, the lower lip and the first toe (bilaterally) were obtained using neuroelectric source imaging. The subjects with congenital upper limb atrophy showed symmetric positions of the left and right side of the lower lip and the first toe, whereas the traumatic amputees with pain showed a significant shift (about 2.4 cm) of the cortical representation of the lower lip towards the hand region contralateral to the amputation side but no shift for the toe representation. In healthy controls, no significant hemispheric differences between the cortical representation of the digits, lower lip or first toe were found. Phantom phenomena were absent in the congenital but extensive in the traumatic amputees. These data confirm the assumption that congenital absence of a limb does not lead to cortical reorganization or phantom limbs whereas traumatic amputations that are accompanied by phantom limb pain show shifts of the cortical areas adjacent to the amputation zone towards the representation of the deafferented body part.

Adult↗
PubMed1998

Manganese superoxide dismutase (MnSOD) and autoantibodies against MnSOD in acute viral infections.

Sera of 146 patients with acute EBV, HAV, HBV, CMV, HSV, and rubella virus infections, and sera from 35 healthy controls were tested for the antioxidant enzyme manganese superoxide dismutase (MnSOD). An enzyme immunoassay that detects all isomeres of the enzyme was developed. The mean MnSOD value of healthy controls was 107 ng/ml. In HAV, HBV and EBV infections characterized by viral replication in internal organs, there was an average 5-fold rise of serum MnSOD, whereas in viral infections with low direct cytopathogenity, such as rubella, CMV and HSV, the MnSOD levels showed only minor rises. These sera were also tested for autoantibodies against MnSOD using a novel sensitive indirect enzyme immunoassay. The average IgM anti-MnSOD concentration in sera of healthy controls was 112 GU. In sera of patients with acute HBV, CMV, HSV or rubella virus infections IgM anti-MnSOD values were only slightly raised above the cut-off level. In contrast, in some patients with acute EBV infections anti-MnSOD concentrations rose up to 20-fold of normal values. In HAV infections the same phenomenon was observed in patients who had reactivated EBV infections. These findings indicate that EBV may facilitate the B-cell response to MnSOD. These autoantibodies may inhibit the protective function of MnSOD and prolong the disease by oxygen injury. Our concept on the pathogenic effect of the autoantibodies against MnSOD emphasizes the importance of the antioxidant enzyme in viral infections.

Acute Disease↗
PubMed1997

Autoantibodies with a protective function: polyreactive antibodies against alkaline phosphatase in bacterial infections.

In patients with acute bacterial infections antibodies directed against a particular bacterial antigen were detected. The molecular mass of this bacterial antigen was 50 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. By comparison of the NH2-terminal amino acid sequence, the 50-kDa antigen was identified as alkaline phosphatase (AP). Affinity-purified antibodies from patient's sera directed against the bacterial AP (anti-alpha) were also shown to react with human and animal AP, which have different structures. Anti-alpha are IgG subtype 3 immunoglobulins, and their light chains are of the kappa type. Upon isoelectric focussing, the anti-alpha formed a scalariform pattern with five to seven bands in the pH range 7-9. The anti-alpha have an opsonic activity and cause a five- to eightfold increase of phagocytosis of gram-positive and gram-negative bacteria. According to their polyreactivity, their sudden rise early in infection, their oligoclonality, as well as their opsonizing properties, they are assumed to be permanently available natural antibodies that take part in early defence mechanisms.

Alkaline Phosphatase↗
PubMed1997

[A nursing intervention study in interdisciplinary cooperation: challenges and problem solving strategies].

Doing a nursing intervention study in two hospitals in collaboration with physicians challenged all participating parties. The course of the study was influenced and partially changed by unforeseen problems. This article presents organizational perspectives on carrying through an intervention study while daily patient care is taking place and discusses specific issues of collaborating with physicians and nurses. Problem solving strategies and consequences from experiences with this study are presented.

Cooperative Behavior↗
PubMed1996

Haemolysis in hepatitis A virus infections coinciding with the occurrence of autoantibodies against triosephosphate isomerase and the reactivation of latent persistent Epstein-Barr virus infection.

Haemolysis has been observed frequently as a complication of acute hepatitis A virus (HAV) infection. However, the pathogenic mechanism has not been elucidated completely. In individual cases the detection of anti-erythrocyte antibodies of unknown specificity was described. The raised serum IgM fraction was shown to consist partially of autoantibodies. Previously, we detected autoantibodies of immunoglobulin class M directed against triosephosphate isomerase (IgM anti-TPI) in patients with infectious mononucleosis. These autoantibodies are able to induce haemolysis. In this study the occurrence of IgM anti-TPI in acute HAV infections and other viral diseases has been investigated. In 33 of 134 patients suffering from HAV infection (IgM anti-TPI was detected. Haematological and chemical data were available from seven of these 33 patients. Mild-to-moderate signs of haemolysis correlating with the IgM anti-TPI titre in the follow-up examinations were demonstrated. The presence of IgM anti-TPI in HAV infections is connected with a reactivation of a latent persistent EBV infection. In other viral infections both the detection of IgM anti-TPI and evidence of a reactivated EBV infection is rare. Thus, we anticipate that IgM anti-TPI antibodies occurring with the reactivation of a latent persistent EBV infection take part in provoking haemolysis in acute HAV infections.

Autoantibodies↗
PubMed1996

LDL stimulates chemotaxis of human monocytes through a cyclooxygenase-dependent pathway.

Monocyte migration into the vessel wall is an early step in atherogenesis. Even though a number of chemotactic factors have been identified, the regulation of the chemotactic response is not clearly understood. As the release of arachidonic acid has been implicated in monocyte chemotaxis, we studied the influence of LDL, which can supply this fatty acid to cells, on the chemotactic mobility of monocytes. Migration of human monocytic U937 cells was abolished by a 30-hour incubation in medium containing lipoprotein-depleted 10% fetal calf serum. Thereafter, human VLDL, LDL, acetyl LDL, methyl LDL, HDL, free cholesterol, linoleic acid, oleic acid, or arachidonic acid was added. At the end of varying incubation periods (0.5 to 8 hours), chemotaxis, viability, and cellular cholesterol content were measured. In the same experimental setting we also studied the effects of the pharmacological agents chloroquine, indomethacin, and acetylsalicylic acid on LDL-mediated chemotaxis. Chemotaxis was restored by LDL in a dose- and time-dependent manner starting at concentrations as low as 5 micrograms/mL and at incubations as brief as 30 minutes. The other lipoproteins tested (VLDL, HDL, acetyl LDL, and methyl LDL) as well as free cholesterol had no comparable effect on chemotaxis. Viability and total cholesterol content did not differ among the groups. Simultaneous incubation of cells with chloroquine, indomethacin, and acetylsalicylic acid reduced restitution of chemotaxis by LDL by 71%, 82%, and 68%, respectively. In contrast, the agents had only slight inhibitory effects on the chemotactic mobility of serum-fed control cells. Incubation with linoleic acid showed a 60% restoration of chemotaxis, whereas arachidonic acid stimulated chemotaxis by 140% compared with the positive control. Preincubation of LDL with the monoclonal antibody MB47 directed against LDL resulted in a significantly reduced migratory response. The data suggest a novel cyclooxygenase-dependent regulatory mechanism of chemotaxis by LDL.

Cells, Cultured↗
PubMed1994

Manganese superoxide dismutase as a target of autoantibodies in acute Epstein-Barr virus infection.

Antibodies directed against the autoantigen p26 were detected in sera from 32 patients with acute Epstein-Barr virus (EBV) infection and clinical symptoms of infectious mononucleosis. P26 has now been identified as the enzyme manganese superoxide dismutase (MnSOD) by comparison of the NH2-terminal amino acid sequence. Antibodies against MnSOD belong to the immunoglobulin class M. They are not detectable in sera of patients with other herpesvirus infections. In the 32 patients investigated, the rise and fall of the autoantibodies coincides with the clinical symptoms. In vitro, the autoantibodies were shown to inhibit the dismutation of superoxide radicals by blocking MnSOD. As presented in the discussion this effect may contribute to the pathogenesis of acute EBV infection.

Acute Disease↗
PubMed1994

Hemolysis and autoantibodies to triosephosphate isomerase in a patient with acute hepatitis A virus infection.

Having returned from a holiday in Southeast Europe, a 30-year-old German woman developed acute hepatitis. Hepatitis A virus (HAV) infection was diagnosed serologically. During the course of the infection, hemolysis was found. IgM antibodies against triosephosphate isomerase (IgM anti-TPI) were detected in the patient's serum from the acute phase of the HAV infection. Affinity purified IgM anti-TPI from the serum reduced the enzyme activity in vitro and caused an increased 51Cr release from erythrocytes. IgM anti-TPI is assumed to be one of the causative agents of hemolysis in HAV infection.

Acute Disease↗
PubMed1993

Prolonged haemolytic anaemia in malaria and autoantibodies against triosephosphate isomerase.

Prolonged haemolysis may accompany infection with Plasmodium falciparum. We observed prolonged haemolysis in 4 of 10 patients with this type of malaria after parasitological cure. IgM antibodies specific for the glycolytic enzyme triosephosphate isomerase were detected in these patients' sera. Clinical recovery and a decrease in haemolysis coincided with a fall in these autoantibodies. In vitro, affinity purified autoantibodies isolated from the sera directed against triosephosphate isomerase induced lysis of erythrocytes and activation of complement as shown by the 51Cr release assay. We assume that autoantibodies against triosephosphate isomerase contribute to the development of prolonged haemolysis and anaemia in P falciparum malaria.

Adult↗