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Biomedical subjects

M Hammer

Publications and source records attributed to M Hammer.

At least 91 records · Page 5Linked to original sources
PubMed1993

Intracellular persistence of chlamydial major outer-membrane protein, lipopolysaccharide and ribosomal RNA after non-productive infection of human monocytes with Chlamydia trachomatis serovar K.

The replication of Chlamydia trachomatis serovar K was studied in human peripheral blood monocytes (PBMo). The intracellular fate of the bacteria was examined by determining the presence of chlamydial major outer-membrane protein (MOMP), lipopolysaccharide (LPS) and ribosomal RNA (rRNA). In-vitro infection of PBMo with C. trachomatis serovar K was not productive. However, chlamydial MOMP antigen, demonstrated by immunofluorescence, was present in PBMo for up to 14 days. Infected monocytes also contained chlamydial rRNA, measured by in-vitro hybridisation, and LPS, measured by enzyme immunoassay, for up to 14 days. These data are compatible with the hypothesis that the infection of PBMo with C. trachomatis may play a role in the systemic distribution of chlamydial antigens, leading to systemic manifestations of urogenital chlamydial infection.

Bacterial Outer Membrane Proteins↗
PubMed1993

The effects of physical abuse on children's social relationships.

Social behavior and peer status of 87 physically abused 8-12-year-old urban children were compared with those of 87 case-matched nonmaltreated classmates. Peer nominations and peer ratings were collected in classrooms, social networks were assessed by child interview, family variables were assessed by interviewing mothers, and behavior problems were rated by parents and teachers. Significant findings were that abused children had lower peer status and less positive reciprocity with peers chosen as friends; they were rated by peers as more aggressive and less cooperative and by parents and teachers as more disturbed; and their social networks showed more insularity, atypicality, and negativity. Social behavior as perceived by peers accounted for a significant portion of the variance in social status; global disturbance measures did not add to this association. Results are discussed in terms of a context of family violence in the development of social maladjustment.

Aggression↗
PubMed1993

[Substance analytic studies of the effectiveness of laser coagulation in diabetic retinopathy].

An order to optimize photocoagulation in diabetic retinopathy, it is necessary to have objective criteria concerning substance-specific fundus changes like blood, melanin, xanthophyl, cytochrome aa3, and light scattering. By means of fundus reflectometry macular reflectance spectra can be measured and are different in normals and in diabetics before or after treatment. If logarithmic difference spectra are used only pathological alterations or changes caused by the coagulation are demonstrable. These difference spectra can be approximated by a linear model function containing the extinction spectra of the substances mentioned above and a term for light scattering. Spectra deconvolution delivers coefficients, describing differences in the substance concentrations between diabetics before and after treatment and age-matched normals. When we examined these coefficients, we found that neither their behavior in diabetic retinopathy nor their reaction to photocoagulation is unique. Thus, it might be possible to obtain references to patient-specific adapted coagulation by deconvolution of the macular reflectance spectra measured before treatment. Classification of the patients in specific types of reaction, according to the shape of the logarithmic difference spectra or the results of the spectra deconvolution, could be a step in deciding on the success of the therapy on a case-to-case basis.

Adult↗
PubMed1992

Spectrometric investigations in ocular hypertension and early stages of primary open angle glaucoma and of low tension glaucoma--multisubstance analysis.

The approximation of logarithmic difference spectra between the reflectance of the normal fundus and the fundus reflectance in different stages of glaucoma is demonstrated by a model. The influences of fundus pigments like oxihemoglobin, melanin, xanthophyll and rhodopsin as well as the intensity and the exponent of the scattered light are optimized. Glaucomatous alterations in the extinction of these pigments and of the scattering parameters are different in the macula, in the papillo-macular bundle and in the parapapillary region temporal to the optic disc. A lack of oxihemoglobin only in the papillo-macular bundle in first relative losses in the visual field function points to a damaged microcirculation in early POAG. In progressive glaucoma the extinction spectrum of xanthophyll is detectable in the papillo-macular bundle. A decreased intensity of the scattered light and an altered scattering exponent are suggestive of a damage in the nerve fiber layer at early stages of glaucoma.

Adolescent↗
PubMed1992

[Arthritic changes in small and large joints in digital and conventional x-ray images].

In order to evaluate the suitability of digital radiography for the diagnosis of skeletal abnormalities, inflammatory joint changes were used to test this technique. Early erosive changes, fine irregularities and marginal lamellar abnormalities demand a high degree of resolution from the imaging method. 6 observers studied images of the hand of 67 and of the foot of 19 patients. Joint changes were staged according to the scheme proposed by Larsen; in this study the early stages predominated. With similar techniques there were no significant differences between the digital and conventional techniques. Images of 39 large joints (knee, shoulder, elbow, ankle) were compared only subjectively since even minor differences in projection were able to obscure some erosions. However, in this case also both techniques appear to be of similar value.

Adult↗
PubMed1992

Disequilibrium of multiple DNA markers on the human Y chromosome.

We characterized four DNA polymorphisms on the Y chromosomes of 123 males from five Caucasian populations. Three markers on the male specific portion of the chromosome varied appreciably in frequency among the populations. When combined, these markers define a limited number of haplotypes compared with the maximum expected on the basis of random association. The associations found in the five groups are qualitatively similar and are thus considered to be relatively stable on an evolutionary time-scale and possibly to predate the divergence of Caucasian populations. However, the haplotype frequencies varied markedly among populations, even between weakly isolated areas such as northern vs. southern Sardinia. This may indicate rapid progression towards fixation of alternative types of Y chromosomes. We also report data suggesting that the same associations no longer hold when examining a marker as close as 275 bp from the boundary of the pseudoautosomal region on the Y chromosome.

Alleles↗
PubMed1991

Neurosecretory cells in the honeybee brain and suboesophageal ganglion show FMRFamide-like immunoreactivity.

Immunocytochemical analysis of the brain and suboesophageal ganglion of the honeybee Apis mellifera L. was combined with Lucifer Yellow backfilling from the corpora cardiaca and intracellular staining of single neurons. It is shown that more than one third of the cells that display FMRFamide-like immunoreactivity (F-LI) project to the corpora cardiaca, suggesting they are neurosecretory. Among the ca. 120 median neurosecretory cells (MNCs) in the pars intercerebralis about 32 show F-LI. The number of immunoreactive MNCs is highly variable and may depend on age and/or diet. Seven of at least 40 lateral neurosecretory cells display F-LI. They project through the brain via the medial branch of the bipartite nervus corporis cardiaci II. In the suboesophageal ganglion three types of immunoreactive neurosecretory cells were identified. Together with the median and the lateral neurosecretory cells in the brain these cells project through a single pair of nerves into the corpora cardiaca suggesting that the nervus corporis cardiaci (NCC) of the honeybee is a fusion of NCC I, II, and III described in other insects.

Animals↗
PubMed1991

Activation of CD16+ effector cells by rheumatoid factor complex. Role of natural killer cells in rheumatoid arthritis.

The role of natural killer (NK) cells in rheumatoid arthritis (RA) remains unclear. A pathogenetic function of rheumatoid factors (RF) also has not been defined. In the present studies, natural killer (NK) cells were examined as a model for FC gamma receptor type III-positive (FC gamma RIII+) cells, with regard to their interaction with RF. NK cell antigen CD16 (FC gamma RIII) and CD56 expression and functional NK and antibody-dependent cell-mediated cytotoxicity (ADCC) activity were compared in peripheral blood lymphocytes and autologous synovial fluid lymphocytes (SFL) of RA patients. Peripheral blood lymphocytes and SFL showed normal CD56 expression. In contrast, both the frequency and the density of CD16 antigen were decreased in SFL. Furthermore, diminished NK cytotoxicity and a significant decrease in ADCC were observed in SF NK cells. In subsequent in vitro studies with normal fresh NK cells, it was demonstrated that IgG-containing RF complexes from RA patients induced a modulation of FC gamma RIII structure from the NK cell surface, a decrease in NK activity, and a complete loss of ADCC. When purified RF was incubated with NK-enriched cell lines from RA patients, increased transcription and subsequent production of interferon-gamma and tumor necrosis factor alpha were observed. These data suggest a direct involvement of RF complexes in the pathogenetic process of chronic inflammation in RA.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1990

[Nosologic concept and new developments in the etiopathogenesis of reactive arthritis].

Reactive inflammatory arthritis is caused by extraarticular infection with different arthritogenic microorganisms. The causative bacteria can not be cultured from synovial specimens, but bacterial antigens have been demonstrated in cells of synovial fluid and synovial membrane, respectively. Thus, latent intraarticular infection may be the cause of reactive arthritis. A model of the etiopathogenesis of reactive arthritis is described on the basis of recent immunological and microbiological findings.

Antibodies, Bacterial↗
PubMed1990

[Yersinia-induced arthritis: new knowledge of pathogenesis, diagnosis and therapy].

Yersinia infections have been identified in rising incidence as the cause of acute or subacute intestinal or extraintestinal diseases in the past two decades. Immunopathological manifestations of Yersinia infections, e.g. Yersinia-induced arthritis, have evoked special interest among clinicians and microbiologists. Beneath epidemiological and clinical characteristics this review focuses on recent progress in pathogenesis and serological and immunohistological diagnosis of Yersiniosis. Possible consequences for newly therapeutical approaches in chronic Yersinia-induced arthritis and spondarthritis were discussed.

Antibodies, Bacterial↗
PubMed1990

Yersinia enterocolitica in the synovial membrane of patients with Yersinia-induced arthritis.

Using a monospecific rabbit antibody against Yersinia enterocolitica outer membrane protein 1, we examined synovial biopsy specimens from 7 patients with Yersinia-induced arthritis. Yersinia were demonstrated in the synovial membrane by indirect immunofluorescence in 4 patients with Yersinia-induced arthritis, but not in 6 control patients with Salmonella-induced arthritis or with rheumatoid arthritis. These findings suggest the persistence of Yersinia in the joints of patients with Yersinia-induced arthritis.

Adult↗
PubMed1990

Multiple sources of P3b associated with different types of information.

This experiment investigated how the P3a, P3b, and Slow Wave components of the event-related brain potential (ERP) respond to manipulations of the nature, timing, and extent of information delivery. There were two experiments in which the total amount of task information was distributed between pairs of successive stimuli (S1 and S2) within each trail. The task was to predict the relation between S1 and S2. In Experiment 1, the S1 could resolve no, partial, or all uncertainty with respect to the prediction outcome (correct or incorrect). Each S1 delivered three types of information: 1) outcome information--which resolved the subjects' uncertainty about the correctness of their prediction; 2) procedural information--which resolved uncertainty about how much outcome information would be delivered by S1; and 3) memory information--the identity of S1, which had to be stored for subsequent comparison with S2. In Experiment 2, the activity of these components was contrasted in two conditions in which the S1 delivered either memory information alone or both memory and procedural information. P3a and Slow Wave were sensitive only to outcome information. P3b was sensitive to all three types of information, and its scalp topography varied as a function of the type of information. The topographic variations indicate that P3b is not a unitary phenomenon but rather is a composite of activity arising from multiple intracranial sources of bioelectric activity.

Adult↗
PubMed1990

Alcohol consumption and pain phobia: toward a unifying theory of alcoholism.

An attempt is made to contribute toward a unifying theory of alcoholism with the concept of "pain phobia" as its central factor. A brief theoretical exposition of pain phobia is offered and results of an empirical study are presented which lend considerable support to the position that pain phobia may be a central factor underlying alcoholism. The research utilizes the Pain Phobia Scale (PPS) as the measure of pain phobia and finds that pain phobia is present to a significantly greater degree in problem drinkers than a norm group and that pain phobia also discriminates non-problem drinkers in the degree of their consumption of alcohol. Suggestions are made for how the concept of pain phobia and the PPS can be useful in the treatment and prevention of alcoholism. The possible relationship between pain phobia and all addictions is also considered.

Adaptation, Psychological↗