Biomedical subjects
Publications and source records attributed to A Müller.
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Somatosensory evoked potentials (SEPs) to median nerve and finger stimulation were analyzed by means of spatio-temporal dipole modelling combined with 3D-NMR tomography in 8 normal subjects. The early SEPs were modelled by 3 equivalent dipoles located in the region of the brain-stem (B) and in the region of the contralateral somatosensory cortex (T and R). Dipole B explained peaks P14 and N18 at the scalp. Dipole T was tangentially oriented and explained the N20-P20, dipole R was radially oriented and modelled the P22. The tangential dipole sources T were located within a distance of 6 mm on the average and all were less than 9 mm from the posterior bank of the central sulcus. In 6 subjects the tangential sources related to finger stimulation arranged along the central sulcus according to the known somatotopy. The radial sources did not show a consistent somatotopic alignment across subjects. We conclude that the combination of dipole source analysis and 3D-NMR tomography is a useful tool for functional localization within the human hand somatosensory cortex.
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Erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA), a potential inhibitor of adenosine deaminase (ADA), was tested as an inhibitor of the soluble cyclic nucleotide phosphodiesterase (PDE) isoenzymes from pig and human myocardium. Four soluble PDE activities were resolved from human papillary muscle extracts using anion exchange chromatography (DEAE Sepharose CL-6B). These activities were designated PDE I-IV according to the nomenclature of Beavo. PDE I was stimulated by Ca(2+)-calmodulin and PDE II by cGMP (1 microM). PDE III was inhibited by cGMP (1 microM) as well as SK&F 94120, and PDE IV by both rolipram and Ro 20-1724. Enzyme kinetics and inhibition constants were similar with the PDE isoenzymes from pig heart. However, porcine myocardium lacked Ca(2+)-calmodulin-stimulated soluble PDE I activity. The present data reveal that EHNA exerted a concentration-dependent inhibition of the cGMP-stimulated PDE II (cGs-PDE) (IC50: 0.8 microM (human), 2 microM (pig)) but did not inhibit the other PDE isoenzymes (IC50 > 100 microM). These findings indicate that EHNA is a potent and, as far as cytosolic PDEs are concerned, selective inhibitor of cGMP-stimulated PDEs. The compound may lend itself for the rational design of other isozyme selective PDE II inhibitors and for examining the specific biological functions of cGs-PDEs. EHNA may be used in systems in which inhibition of ADA is of no concern. Conversely, dual inhibition of both ADA and cGs-PDE by EHNA may cause accumulation of two inhibitory metabolites, adenosine and cGMP, which may act in synergy to mediate diverse pharmacological responses, including antiviral, antitumour and antiarrhythmic effects.
Microsporidiosis is a common finding in HIV-infected patients who have diarrhoea. The species most commonly causing gastrointestinal disease is Enterocytozoon bieneusi. Recently Septata intestinalis has been described as a cause of diarrhoea and disseminated infection in patients with AIDS. A 44-year-old homosexual man with severe immunodeficiency (CD4 cell count 40/microliters) had a history of watery diarrhoea for 2 weeks. Microsporidian spores measuring 1.2 to 1.5 x 2.5 to 3.0 microns were found in stool samples. Electron microscopy of duodenal biopsies confirmed the diagnosis of intestinal microsporidiosis and showed parasitophorous vacuoles with the typical ultrastructure of S. intestinalis. The patient was treated with albendazole (400 mg twice daily) and became asymptomatic within 4 days. No spores could be detected in stool samples after a treatment period of 14 days. About 25 infections with S. intestinalis have been reported to date, and the case presented here is the first in a German patient.
A 1.6 kb repetitive DNA sequence (RPS) from Petunia hybrida was identified that destabilizes expression of a GUS marker transgene. Following polyethylene glycol (PEG)-mediated tobacco and petunia protoplast transformations, GUS expression patterns analysed on callus and plant levels were clearly more variable when constructs contained the RPS sequence. The effect on transgene expression required chromosomal integration since the two different RPS constructs employed did not exhibit reduced levels of GUS activities in transient assays. DNA methylation analysis implies a hypermethylated default state of endogenous RPS copies present in the petunia genome. Analysis of the transgene DNA in different transgenic tobacco plants showed almost complete hypermethylation of a particular Hhal site of the RPS sequence. It is proposed that, due to the presence of specific signals within the RPS region or based on interaction of RPS with other endogenous homologous sequences, RPS functions as an initiation region for de novo methylation and induces expression variegation in adjacent sequences.
Microsporidia are obligate intracellular protozoan parasites that infect a broad range of vertebrates and invertebrates. They are increasingly recognized as human pathogens, especially in patients infected with human immunodeficiency virus (HIV). Organisms of the genus Encephalitozoon have been implicated as a major cause of disseminated microsporidian infections in persons with AIDS. Until recently, E. hellem was the only Encephalitozoon species confirmed by antigenic or nucleic acid methods to have infected humans. We describe the clinical course and morphological features of a case of disseminated microsporidian infection with Encephalitozoon cuniculi in an HIV-infected patient with chronic sinusitis, rhinitis, and keratoconjunctivitis. Parasites were found in conjunctival swab, nasal discharge, sputum, urine, stool, and duodenal biopsy specimens, but no pulmonary, renal, or gastrointestinal symptoms were documented. The patient was treated with albendazole (400 mg po b.i.d.), resulting in complete remission of his ocular and nasal symptoms, and microsporidian spores disappeared from all sites. To our knowledge, this case is only the second of E. cuniculi infection in humans that has been confirmed by either antibody- or nucleic acid-based methods, and it is the first in which an Encephalitozoon species has been found in the intestinal tract of a human. Microsporidiosis is an important emerging opportunistic infection in HIV-infected patients and, as documented in this report, has an expanding clinicopathologic spectrum.
Rabbits nurse briefly only once each night and are frequently both pregnant and lactating. To investigate the influence of the daily timing of nursing on parturition, does (n = 10 per group) were remated after giving birth and were allowed to nurse under one of three schedules: group 1 every 24 h in the light, group 2 every 24 h in the dark, and group 3 at any time. Whereas does from groups 2 and 3 nursed and gave birth normally, does of group 1, forced to nurse out of phase with the normal schedule, showed disturbed nursing behavior and prolonged gestation followed by many stillbirths. In a second experiment, pregnant does (n = 10 per group) were treated daily either with oxytocin (OT) in the light (group 4), with OT in the dark (group 5), or with progesterone (P; group 6) or saline (group 7) in the light. All does gave birth normally except those of group 4, which responded similarly to group 1 does. These findings demonstrate that in the rabbit, parturition may be seriously compromised if does nurse out of phase with the normal schedule and suggest that a shift in the daily timing of OT release may underlie this.
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Intestinal microsporidiosis has been implicated as a major cause of chronic diarrhea in human immunodeficiency virus (HIV)-infected patients. So far diagnosis depends on direct visualization of the parasites by light and transmission electron microscopy. We evaluated the diagnostic value of microsporidian DNA amplification by PCR on duodenal biopsy specimens obtained from patients with and without intestinal microsporidiosis caused by Enterocytozoon bieneusi. Thirteen HIV-infected patients (all CDC stage C3) were studied. Eight patients had intestinal microsporidiosis caused by E. bieneusi (n = 6), Septata intestinalis (n = 1), and Encephalitozoon cuniculi (n = 1); microsporidioses were diagnosed by light microscopy of stool samples and confirmed by light and electron microscopy of intestinal biopsy specimens. Five patients had no microsporidia in their stool samples or in their intestinal biopsy specimens, as examined by light and electron microscopy. Additionally, DNA prepared from Toxoplasma gondii derived from mouse ascites was used as a further control. A 353-bp DNA fragment of the small-subunit rRNA gene could be amplified from all six biopsy specimens infected with E. bieneusi, and the nature of the PCR products was confirmed by Southern blot hybridization. No amplification of DNA fragments was seen by using DNA extracted from biopsy specimens with S. intestinalis or E. cuniculi infection or without microsporidian infection and with template DNA extracted from T. gondii. The results suggest that PCR testing of intestinal biopsy specimens may be a useful approach to diagnosing microsporidiosis in HIV-infected patients.
The APC gene is mutated in the germline of people from families where there is a predisposition to develop polyposis coli. Many mutations have been described but the relation between their site and the phenotypic expression of the disease remains unclear. The most commonly seen mutation occurs at codon 1309. Many other mutations have been described towards the 5' end of exon 15 of the APC gene but comparatively few have been seen towards the 3' end. Recent reports have indicated the possibility of a functional boundary with respect to severity and age of onset of disease, which lies towards the 5' end of the gene. This report describes a large family whose affected members present with a very variable phenotype ranging from an early onset and severe form to a comparatively mild later onset one. The mutation that predisposes to disease in this family is at a previously undescribed site that lies towards the 3' end of exon 15 of the APC gene, which results in a stop codon. Interestingly, the stop codon is 63 codons downstream of the mutation and therefore may affect the expression of the disease. The addition of this mutation to the growing list of mutations described in the APC gene may provide some insight into the genotype/phenotype relation of the disease thus contributing to the understanding and significance of mutations at specific sites in the APC gene.
AIMS: To detect intestinal microsporidiosis in paraffin wax embedded biopsy specimens using a fluorescence technique incorporating optical brighteners. METHODS: Eight HIV infected patients with confirmed intestinal microsporidiosis (six with Enterocytozoon bieneusi, one with Encephalitozoon intestinalis and one with Encephalitozoon cuniculi infection) and 10 without infection were studied. Tissue sections of paraffin wax embedded duodenal biopsy specimens were stained with 1% Uvitex 2B, coded and analysed independently by two investigators. RESULTS: In all eight cases with confirmed intestinal microsporidian infection, spores could be detected easily in tissue sections using the fluorescence technique. Spores or other elements consistent with microsporidiosis were not found in the 10 patients without infection. CONCLUSION: Staining of tissue sections from paraffin wax embedded intestinal biopsy specimens with stains incorporating Uvitex 2B is a rapid and easy technique for the diagnosis of intestinal microsporidiosis.
A workshop was convened, at which seven enzyme-linked immunosorbent assays (ELISAs) were compared with virus isolation for the detection of viraemia in serial blood samples collected from six pigs at up to fourteen days after inoculation with classical swine fever virus. All ELISAs were of the double antibody sandwich type, using monoclonal and/or polyclonal antibodies to detect a variety of viral proteins in leukocytes, or in anti-coagulated blood or serum. Compared to virus isolation, specificity of the ELISA was good: only one sample found negative by virus isolation yielded a positive result in a single ELISA. Some false-negative results occurred with samples collected at up to eight days after inoculation, but all tests found samples collected between nine and fourteen days post-inoculation to be positive. The ELISAs require less-specialised facilities and can be performed much more rapidly than virus isolation. They are therefore extremely promising tools for screening large numbers of live pigs.
The correlation between cellular growth and microfilament-dependent morphology was investigated. It was found that the proliferative growth of various nontransformed cell lines does not only depend on cell adhesion to a suitable substratum and cell flattening but also on intact microfilaments. Disintegration of microfilaments by cytochalasin D (CD) as well as lactrunculin (LAT)-A and LAT-B is correlated with a strong decline of the number of DNA-synthesizing cells during a period of 8 to 12 h after application of the drug. RNA and protein synthesis are reduced already after a preincubation time of 2 h. Although microinjected rhodamine-phalloin is colocalized with microfilaments there is no stabilizing effect against CD even at high phaloidin concentrations. Microinjection of DNAse I results in a strong alteration of the microfilament system. The disorganization of microfilaments was correlated with a moderate decrease of protein synthesis 2 h after microinjection, whereas RNA synthesis remained unchanged, if RNase-free DNase I was used. The number of DNA-synthesizing cells was somewhat diminished 24 h after microinjection. Furthermore, the microfilament system is disorganized by microinjection of gelsolin and gelsolin segment 1 + 2, respectively. The severing the microfilaments by gelsolin is correlated with a significant restriction of RNA and protein synthesis during a period of 2 to 4 h after injection, but the labeling index remaining unchanged. Therefore, we assume that inhibition of the G0-G1-S transition is only caused by a disintegration of microfilaments lasting longer than 4 h. The significance of microfilament organization for growth regulation is discussed.
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Thyroid surgery is seldomly indicated in childhood and adolescence mainly because of suspicious nodules or proven carcinoma. Indications for operation in Graves disease and focal autonomy are discussed controversially, however. In a retrospective case control study two of our 6 patients up to 18 years demonstrated differentiated thyroid cancer with focal autonomy in the autonomous nodule. Other studies show similar results. Thyroid surgery is therefore warranted in all children and adolescents with focal thyroid autonomy.
A pregnant wild boar and two wild boar weaners were inoculated intranasally with a field isolate of classical swine fever virus (CSFV) recently derived from a diseased domestic pig. The clinical, pathological and haematological findings noted in the young wild boars were comparable to those in domestic weaner pigs inoculated with the same virus isolate. Both wild boars showed the acute haemorrhagic form of CSF, one animal died 18 days post inoculation (p. i.) and the second one had to be euthanized when moribund two days later. The wild boar sow did not show any signs of illness p. i. but seroconversion was noticed. Twenty-eight days p. i. birth was given to six clinically healthy offsprings. One of the newborn proved to be viraemic until death when 39 days of age. Except for poor growth no other symptoms were noticed in this piglet. The non-viraemic litter mates remained healthy, although they had close contact to the persistently infected piglet. High titres of neutralizing antibodies against CSFV were measured in the serum samples of these offsprings. All findings were more or less in accordance with observations previously made in domestic pigs when infected with CSFV around 85 to 90 days of gestation. The wild boar was calculated to have been inoculated at about 87 to 92 days of gestation.
OBJECTIVES: It is known that neutrophilic leukocytes contribute to cellular damage in the course of cardiac ischemia/reperfusion. A role in arrhythmogenesis, although controversial, has been ascribed in some studies to the leukocytes, but investigations evaluating possible beneficial effects of inhibitors of neutrophil adhesion or transmigration are still missing. METHODS: Isolated spontaneously beating rabbit hearts, perfused with saline solution at constant pressure according to the Langendorff technique, were treated with 15 min infusion of autologous neutrophils. 10 min after the start of this infusion the hearts were submitted to coronary occlusion (LAD) for 30 min followed by 30 min reperfusion. Four experimental groups were investigated: (1) saline-perfused control hearts, (2) leukocyte-perfused hearts, (3) leukocyte-perfused hearts treated with RGDS peptide, (4) leukocyte-perfused hearts treated with chondroitin sulfate C. In all experiments epicardial potential mapping was carried out (256 unipolar leads). At the end of each experiment the hearts were prepared for histology and after staining leukocyte accumulation in the ischemic zone, in the border zone and in the non-ischemic area was evaluated. RESULTS: In leukocyte-perfused hearts submitted to ischemia/reperfusion we found a somewhat enhanced arrhythmogenesis, enhanced ST-segment deviation, and a 2-3-fold increase in leukocyte accumulation in the ischemic and border zone as compared to the non-ischemic tissue as well as increased dispersion of epicardial potential duration especially during reperfusion. These changes and the leukocyte accumulation could be suppressed by treatment with RGDS and to a somewhat lesser extent with chondroitin sulfate C. In addition, arrhythmogenesis could be reduced but not completely suppressed by that treatment. CONCLUSIONS: From these results we conclude that: (a) leukocytes exert an aggravating effect in arrhythmogenesis during ischemia/reperfusion, (b) the arrhythmogenic substrate for this effect may consist of an enhanced dispersion of potential duration and (c) that inhibition of leukocyte accumulation can at least partially reduce arrhythmogenesis and may be of therapeutic interest as an additional treatment.