Search PubMed⌕ Search

Biomedical subjects

A Werner

Publications and source records attributed to A Werner.

At least 91 records · Page 5Linked to original sources
PubMed1999

Neuroglial activation repertoire in the injured brain: graded response, molecular mechanisms and cues to physiological function.

Damage to the central nervous system (CNS) leads to cellular changes not only in the affected neurons but also in adjacent glial cells and endothelia, and frequently, to a recruitment of cells of the immune system. These cellular changes form a graded response which is a consistent feature in almost all forms of brain pathology. It appears to reflect an evolutionarily conserved program which plays an important role in the protection against infectious pathogens and the repair of the injured nervous system. Moreover, recent work in mice that are genetically deficient for different cytokines (MCSF, IL1, IL6, TNFalpha, TGFbeta1) has begun to shed light on the molecular signals that regulate this cellular response. Here we will review this work and the insights it provides about the biological function of the neuroglial activation in the injured brain.

Animals↗
PubMed1999

Regulation of the LIM-type homeobox gene islet-1 during neuronal regeneration.

Peripheral nerve lesion leads to prominent changes in gene expression in the injured neurons, a process co-ordinated by transcription factors. During development the transcription factor islet-1 plays an important role in differentiation and axogenesis. In axotomized adult neurons a process of axonal regrowth and re-establishment of the neuronal function has to be activated. Thus, we studied changes in the expression of islet-1 after axotomy, under the assumption that frequently developmentally regulated factors are reactivated during neuronal regeneration. We investigated the regulation of islet-1 expression with (i) semi-quantitative reverse transcription polymerase chain reaction and (ii) confocal microscopy in combination with quantitative image analysis. Islet-1 expression was suprisingly down-regulated in motoneurons and sensory neurons of adult rats after axotomy. A maximal reduction in the expression level was reached between day 3 and 7 after nerve lesion, a period of extensive axonal sprouting. Islet-1 expression attained control level at day 42 after lesion, a time-point at which target reinnervation takes place. The decreased expression of islet-1 during axonal regeneration is in contrast to the high levels of islet-1 expression during axogenesis in the developing nervous system. Thus, the proposed role of islet-1 in axonal target finding during axogenesis could not be confirmed in the adult rat. The observed down-regulation of islet-1 rather suggests that the activation of downstream genes important for the embryonic pattern of axonal path finding is suppressed. Moreover, in the adult nervous system islet-1 might be one of the transcription factors regulating the expression of proteins significant for the physiological intact neuronal phenotype.

Animals↗
PubMed1999

Renal artery stenosis treated with stent deployment: indications, technique, and outcome for 108 patients.

From January 1993 to May 1996, 108 patients (64 men, 44 women; mean age, 72 years; age range, 37 to 87 years) underwent 125 percutaneous transluminal angioplasties and stent implantations primarily for atherosclerotic lesions of the renal artery. Sixty-four patients underwent treatment for renovascular hypertension (two antihypertensive medications or more), 32 patients underwent treatment for a combination of hypertension and renal failure (serum creatinine level >/=1.6 mg/dL), and a small group of six patients (5%) without hypertension or diminished renal function underwent treatment to prevent the progression to renal artery occlusion and kidney loss. Thirty-three patients (31%) had renovascular hypertension that was classified as severe on three or more medications, 31 patients (29%) had renovascular hypertension that was classified as moderate on two medications, and 38 patients (35%) had renovascular hypertension that was classified in the mild group on a single antihypertensive agent. Stenotic lesions were located at the ostium of the renal artery in 82 cases (65%) and were ostial-adjacent (<5 mm from renal ostium) in the other 43 cases (34%). A total of 125 stents were deployed in 125 arteries (procedural success 97.6%). Renovascular hypertension either was cured or was improved in 73 patients (68%), with 14 patients (13%) considered cured (normotensive on no medications). The conditions of 29 patients (27%) were unchanged, and 6 patients (5%) had worsening hypertension after surgery. We were unable to demonstrate a statistically significant improvement in serum creatinine levels after renal artery balloon angioplasty/stenting. Complications occurred in a total of nine cases (7.2%), six of which were related to technical problems. One patient had worsening renal insufficiency caused by contrast agent, and another patient had a perinephric hematoma develop that necessitated evacuation. There were four postoperative deaths (30-day mortality). Two of these deaths were caused by postoperative myocardial infarction. The other two patients had progressive renal failure develop that necessitated dialysis. These patients later died of the disease process despite supportive care. Follow-up renal artery duplex scan studies and angiograms were available on 96 patients (76%). The mean peak systolic renal/aortic ratio on duplex scanning was 2.2. Life-table analysis yielded a 74% primary patency rate and an 85% secondary patency rate at 36 months. This retrospective analysis showed the effectiveness of combining percutaneous transluminal angioplasty with stent deployment for significant renal artery stenosis to treat renovascular hypertension.

Adult↗
PubMed1999

Visualization of collagenase-induced cartilage degradation using NMR microscopy.

RATIONALE AND OBJECTIVES: There is an ongoing discussion about the role of collagenase as a specific cartilage-degrading enzyme in the course of osteoarthritis. Using NMR microscopy, the influence of collagenase on the cartilage structure was investigated. METHODS: High-resolution MR imaging investigations were performed at 7.1 Tesla to study the influence of collagenase on the cartilage structure of pig femoral condyles. Two different contrast agents (polylysine-Gd-DTPA and liposome-entrapped contrast agents) were tested to improve the NMR microscopic visualization of the damaged cartilage regions. RESULTS: The NMR microscopic investigations showed that collagenase affects only the cartilage surface. Changes within the cartilage layer were not detected. However, after the application of specific contrast agents, it was possible to detect with great sensitivity collagenase-induced damage to the collagen network on the cartilage surface and the superficial cartilage zones. The application of liposome-entrapped contrast agents improved the visualization of the collagenase-degraded superficial cartilage zone. CONCLUSIONS: These findings could be of great importance when estimating the state of the articular cartilage. The degree of fibrillation of the cartilage surface in the course of osteoarthritic disease can be visualized by MR tomography with a high degree of sensitivity.

Animals↗
PubMed1999

Long-term follow-up of endoluminal grafting for aneurysmal and occlusive disease in the superficial femoral artery.

PURPOSE: To examine the long-term outcome of patients treated with endoluminal grafts (ELGs) for aneurysmal and occlusive disease in the femoropopliteal (FP) segment. METHODS: ELGs of radially expandable polytetrafluoroethylene with terminal Palmaz stents were used to form intimal conduits to revascularize lengthy occlusive disease and exclude aneurysms in the FP segment. Patient records were reviewed retrospectively for outcome. RESULTS: Fifty-five (98%) of 56 ELGs were placed successfully in 51 patients treated from August 1993 to February 1996. Over a mean 36-month follow-up, 28 (50%) ELGs occluded. Half of these failures reflected early technical difficulties. There were 11 (20%) stent stenoses, 6 in the proximal stent and 5 in the distal device. The majority of the graft failures were treated with endovascular techniques; however, FP bypass was required in 7 (25%) patients, while 2 (7%) were not treated. Life-table analysis demonstrated 46% primary and 68% secondary patency rates at 24 months. Among demographic and procedural variables, only previous dilation or stent procedures in the target artery was associated with failure (p < 0.0001). CONCLUSIONS: The prototype ELG used in this series demonstrated durability similar to conventional surgical therapy utilizing synthetic material. Endoluminal grafting of FP lesions may be a more durable alternative to classical bypass once devices and techniques are refined.

Aged↗
PubMed1999

Survey on equine cryptosporidiosis in Poland and the possibility of zoonotic transmission.

The present study was undertaken to investigate the prevalence of Cryptosporidium infection in horses used for recreational riding as well as in humans. A total of 106 faecal specimens from horses raised in 4 localities of western Poland and 6 stool samples from 3 persons who had constant or sporadic contact with horses were screened microscopically for oocysts using modified Ziehl-Neelsen staining. Enzyme immunoassay (EIA) was additionally used for the detection of coproantigen in human stool samples as well as in 43 randomly selected horse faecal samples. The overall infection rate of horses determined by microscopic examination was 9.4%. To our knowledge, this is the first report of cryptosporidial infection in horses in Poland. The infection was identified only in adult horses raised on 2 of 4 examined farms. The intensity of equine cryptosporidial infection was light, as a rule. None of the infected horses appeared clinically ill. The real overall infection rate in horses could be higher. Among 43 faecal specimens additionally processed by EIA, 5 samples were positive both for oocysts and coproantigen, whereas in 7 faecal samples only the parasite coproantigen was detected. The morphometric analysis of oocysts indicated that the horses were most probably infected with C. parvum. Of 3 examined persons, cryptosporidial infection was identified in a rider who had sporadic contact with horses.

Animals↗
PubMed1999

[Cryptosporidiosis in HIV-positive patients].

Cryptosporidium parvum is a coccidian parasite that affects millions of people worldwide. Clinical outcome of human cryptosporidiosis differs between immunocompetent and immnunodeficient individuals. C. parvum is responsible for causing protracted and life-threatening diarrhea, biliary, and pulmonary infections in immunocompromised persons, especially in patients with AIDS. Though no effective treatment has been found so far, early diagnosis may be useful in controlling the infection. Thirty-eight stool specimens obtained from 35 HIV-positive patients admitted to the Clinic of Infectious Diseases in Poznań, Poland, were examined for the detection of oocysts, coproantigen and DNA of Cryptosporidium using standard microscopic, immunologic and molecular diagnostic methods. The presence of Cryptosporidium was detected in 10 HIV-positive patients. Oocysts, coproantigen and DNA of this parasite were identified solely in one specimen while Cryptosporidium DNA was detected in 8 specimens. Cryptosporidium coproantigen was found only in one sample. Although, the PCR was the most useful technique in the detection of Cryptosporidium in HIV-positive patients it should be noted that PCR has many pitfalls and needs to be carefully controlled to avoid both false positive and false negative results.

AIDS-Related Opportunistic Infections↗
PubMed1998

Immune surveillance in the injured nervous system: T-lymphocytes invade the axotomized mouse facial motor nucleus and aggregate around sites of neuronal degeneration.

Although the CNS is an established immune-privileged site, it is under surveillance by the immune system, particularly under pathological conditions. In the current study we examined the lymphocyte infiltration, a key component of this neuroimmune surveillance, into the axotomized facial motor nucleus and analyzed the changes in proinflammatory cytokines and the blood-brain barrier. Peripheral nerve transection led to a rapid influx of CD3-, CD11a (alphaL, LFA1alpha)- and CD44-immunoreactive T-cells into the axotomized mouse facial motor nucleus, with a first, low-level plateau 2-4 d after injury, and a second, much stronger increase at 14 d. These T-cells frequently formed aggregates and exhibited typical cleaved lymphocyte nuclei at the EM level. Immunohistochemical colocalization with thrombospondin (TSP), a marker for phagocytotic microglia, revealed aggregation of the T-cells around microglia removing neuronal debris. The massive influx of lymphocytes at day 14 was also accompanied by the synthesis of mRNA encoding IL1beta, TNFalpha, and IFN-gamma. There was no infiltration by the neutrophil granulocytes, and the intravenous injection of horseradish peroxidase also showed an intact blood-brain barrier. However, mice with severe combined immunodeficiency (SCID), which lack differentiated T- and B-cells, still exhibited infiltration with CD11a-positive cells. These CD11a-positive cells also aggregated around phagocytotic microglial nodules. In summary, there is a site-selective infiltration of activated T-cells into the mouse CNS during the retrograde reaction to axotomy. The striking aggregation of these lymphocytes around neuronal debris and phagocytotic microglia suggests an important role for the immune surveillance during neuronal cell death in the injured nervous system.

Animals↗
PubMed1998

Chloride conductance and Pi transport are separate functions induced by the expression of NaPi-1 in Xenopus oocytes.

Expression of the protein NaPi-1 in Xenopus oocytes has previously been shown to induce an outwardly rectifying Cl- conductance (GCl), organic anion transport and Na+-dependent Pi-uptake. In the present study we investigated the relation between the NaPi-1 induced GCl and Pi-induced currents and transport. NaPi-1 expression induced Pi-transport, which was not different at 1-20 ng/oocyte NaPi-1 cRNA injection and was already maximal at 1-2 days after cRNA injection. In contrast, GCl was augmented at increased amounts of cRNA injection (1-20 ng/oocyte) and over a five day expression period. Subsequently all experiments were performed on oocytes injected with 20 ng/oocytes cRNA. Pi-induced currents (Ip) could be observed in NaPi-1 expressing oocytes at high concentrations of Pi (>/= 1 mm Pi). The amplitudes of Ip correlated well with GCl. Ip was blocked by the Cl- channel blocker NPPB, partially Na+-dependent and completely abolished in Cl- free solution. In contrast, Pi-transport in NaPi-1 expressing oocytes was not NPPB sensitive, stronger depending on extracellular Na+ and weakly affected by Cl- substitution. Endogenous Pi-uptake in water-injected oocytes amounted in all experiments to 30-50% of the Na+-dependent Pi-transport observed in NaPi-1 expressing oocytes. The properties of the endogenous Pi-uptake system (Km for Pi > 1 mM; partial Na+- and Cl--dependence; lack of NPPB block) were similar to the NaPi-1 induced Pi-uptake, but no Ip could be recorded at Pi-concentrations </=3 mM. In summary, the present data suggest that Ip does not reflect charge transfer related to Pi-uptake, but a Pi-mediated modulation of GCl.

Animals↗
PubMed1998

Regulation of MCSF receptors on microglia in the normal and injured mouse central nervous system: a quantitative immunofluorescence study using confocal laser microscopy.

The macrophage colony-stimulating factor (MCSF) is a 40-76-kD glycoprotein that plays an important role in the activation and proliferation of microglia both in vitro and in injured neural tissue. Here, we examined the regulation of MCSF receptor (MCSFR) and MCSF in the normal and injured mouse central nervous system (CNS) by using confocal laser microscopy, quantitative immunofluorescence, and reverse transcriptase-polymerase chain reaction (RT-PCR) techniques. Immunohistochemistry on fixed, floating tissue sections demonstrated low to moderate MCSFR immunoreactivity (MCSFR-IR) on microglia in the gray and white matter throughout the mouse CNS in the forebrain, brainstem, cerebellum, and spinal cord. High levels of MCSFR-IR were restricted to the superficial layer of the spinal cord dorsal horn, substantia nigra, and area postrema, a CNS region that lacks the blood-brain barrier. CNS injury led to a strong and specific increase in MCSFR-IR in the directly injured dorsal forebrain, in the cervical spinal cord (C2) after transection of the sensory, minor occipital nerve, and in the axotomized facial motor nucleus. Further investigation at the mRNA level in the facial nucleus model showed that this increase was accompanied by a rapid induction of the transcript for MCSFR, with a peak 1-2 days after injury, but only a constitutive expression of MCSF-mRNA. In summary, although normal levels of MCSF receptor in most microglia are low, microglial activation is accompanied by a rapid and massive increase. In view of the constitutive expression of MCSF, the early upregulation of the MCSF receptor may play a central role in preparing these macrophage-related cells to take part in the cellular response to CNS injury.

Animals↗
PubMed1998

Translated anti-sense product of the Na/phosphate co-transporter (NaPi-II).

The homeostasis of Pi in marine teleosts is maintained by renal Pi secretion as well as by Pi reabsorption. A Na/Pi co-transport system belonging to the NaPi-II protein family is instrumental in tightly controlled renal Pi handling in mammals and fish. We have isolated an NaPi-II related cDNA from winter flounder. It was cloned from a female gonad cDNA library and is 624 bp long. The transcript is expressed in female and male flounder gonads as well as in kidney and intestine, although at very low levels. RNase H digestion experiments revealed an opposite orientation of the transcript with regard to NaPi-II-related mRNA. The anti-sense orientation was confirmed by genomic sequence analysis and Southern blotting. Alluding to the sense transcript, the anti-sense transcript was denoted IPAN. The open reading frame of IPAN encodes a basic protein of 68 amino acid residues. Immunohistochemistry confined the anti-sense related protein, Ipan, to a submembranous compartment of immature oocytes, suggesting a role in oocyte development. In kidney and intestine Ipan is partly co-localized with the Na/Pi co-transporter, implying a regulatory function for the anti-sense protein. However, direct protein-protein interaction could not be established. The existence of a putative open reading frame in other species extends the biological significance of the novel protein.

Amino Acid Sequence↗
PubMed1998

The Na+-phosphate cotransport system (NaPi-II) with a cleaved protein backbone: implications on function and membrane insertion.

1. Renal handling of inorganic phosphate (Pi) involves a Na+-Pi cotransport system which is well conserved between vertebrates. The members of this protein family, denoted NaPi-II, share a topology with, it is thought, eight transmembrane domains. The transporter is proposed to be proteolytically cleaved within a large hydrophilic loop in vivo. 2. The consequences of an interrupted backbone were tested by constructing cDNA clones encoding different N- (1-3 and 1-5) and C-terminal (4-8 and 6-8) complementary fragments of NaPi-II from winter flounder. When the cognate fragments were used in combination (1-3 plus 4-8; 1-5 plus 6-8) they comprised the full complement of the putative transporter domains. 3. None of the four individual fragments or the 1-5 plus 6-8 combination when expressed in Xenopus oocytes increased Pi flux. Coexpression of fragments 1-3 plus 4-8 stimulated transport activity identical to that for expressed wild-type NaPi-II with regard to pH dependency and Km for Na+ and Pi binding; however, the maximal transport rate (vmax) was lower. 4. Immunohistochemistry on cryosections confined the functionally active 1-3 plus 4-8 combination to the oocyte membrane. This was not the case for the 1-5 plus 6-8 combination or any of the individual fragments, all of which failed to induce fluorescence. 5. A second immunohistochemical approach using intact oocytes allowed determination of the extracellular regions of the protein. Epitopes within the loop between transmembrane domains 3 and 4 enhanced fluorescence. Neither N- nor C-terminal tags induced fluorescence.

Animals↗
PubMed1998

MR-microscopic visualization of anisotropic internal cartilage structures using the magic angle technique.

NMR microscopic studies of articular cartilage at 7.1 T are presented. Using a special experimental design, T2-weighted spin-echo images of cartilage-bone plugs were taken under variable angles with respect to the static magnetic field B0 to visualize the angular-dependent representation of internal matrix structures mediated by the collagen network arrangement. To quantify the observed orientational effect in the MR images, exact measurements of the transverse relaxation time T2 were taken using the CPMG sequence. The NMR experiments show the strong influence of the cartilage orientation with respect to the static magnetic field on the inhomogeneous appearance of the articular cartilage in the MR image. Additionally performed polarization light microscopic investigations demonstrate the direct relation between the oriented collagenous structures and the anisotropic regions observed in the MR images. A simple cartilage matrix model derived from the experimental findings is proposed, and consequences for the clinical assessment of the articular joint are discussed.

Aged↗
PubMed1998

[Operation of multidisciplinary, interventional 0.5 Tesla magnetic resonance tomograph. Technical and logistic problems and initial clinical results].

Multidisciplinary usage of a MRI system with a superconducting 0.5-T magnet (Signa SP, General Electric) with a vertical gap suited for diagnostic and therapeutic interventions raises complex problems. The MR equipment, including a special localizing system and the instruments for diagnostic and therapeutic interventions, is described. Before putting the system into operation tests were necessary to check MR compatibility of various materials and instruments and to build some auxiliary equipment. We report on the coordinating activities of the radiologist in the context of MR use by different medical specialities. Within the course of 12 months, 428 examinations/interventions of different kinds were carried out, among them 75 functional examinations of the spine or of joints, 31 diagnostic biopsies, 23 cerebral biopsies, and 23 operations. The special design of the Signa SP allows the whole scale of functional examinations, up to complete neurosurgical interventions, in the sitting position and under nearly real-time imaging control.

Equipment Design↗
PubMed1998

Molecular cloning and sequence analysis of interleukin 16 from nonhuman primates and from the mouse.

Interleukin 16 (IL-16) is synthesized as a 67 000 Mr precursor (pro-IL-16), but only a carboxy terminal part of 12 000-14 000 Mr is secreted by CD8(+) lymphocytes. This lymphokine binds to CD4 and has been shown to induce migration, affect the activation state of T cells, and inhibit immunodeficiency virus replication. It has been suggested that CD8(+) cell-derived soluble factors play a pivotal role in protecting natural-host nonhuman primates from developing immunodeficiency following SIV infection. In a first attempt to address this question, we cloned and sequenced the IL-16 cDNA from different primates. Here we report the pro-IL-16 sequence from chimpanzees, African green monkeys (AGM), rhesus macaques, and cynomolgus macaques. In order to compare and analyze structural motifs possibly involved in processing, intracellular targeting, or secretion, we extended our study to the New World monkeys saimiri and aotus and to the mouse. Alignments of deduced amino acids reveal that the human protein shares 99% similarity to that of chimpanzees, approximately 95% to rhesus, cynomolgus and AGM, about 90% to aotus and saimiri, and 77.5% to the mouse. Phylogenetic analyses revealed the expected evolutionary groupings.

Amino Acid Sequence↗
PubMed1998

[Cyclophotocoagulation with the diode laser. Study of long-term results].

UNLABELLED: To assess the clinical effectiveness of glaucoma therapy with diode laser cyclophotocoagulation, 106 eyes (51 eyes with primary open-angle glaucoma, 22 eyes with secondary glaucoma, 10 eyes with narrow-angle glaucoma, 23 eyes with other glaucomas) of 87 patients were treated. Using a diode laser coupled with a fiberoptic probe, ending in a focusing tip, all eyes were treated with 24-30 spots over 360 degrees and 2.8-3.5 J of energy, 1.5 mm posterior to the limbus. The intraocular pressure was obtained over a period of time until 8-24 months after operation. Additionally, morphological changes of the ciliary body were observed in 25 eyes by means of ultrasound biomicroscopy. RESULTS: The IOP decreased from a baseline mean of 25.0 +/- 5.7 mm Hg to 17.6 +/- 5.3 mm Hg directly after operation and increased slightly to 18.0 +/- 6.0 mm Hg in the following 24 months. Successful control of IOP (IOP constantly < 22 mm Hg or pain relief in blind eyes) occurred in 90 of 106 eyes (84.9%). In 23 eyes more than one treatment was given. In 6 eyes another IOP-reducing operation had to be performed. In 19 eyes slightly elongated intraocular inflammatory reactions were seen, without any serious complications. The morphological investigations showed in 22 of 25 cases temporary edema of the ciliary body. A temporary detachment of the ciliary body was seen in 8 eyes. CONCLUSIONS: Diode laser cyclophotocoagulation is an effective and safe procedure to reduce IOP in different types of glaucoma over a long time. Postoperatively, a temporary inflammatory reaction of the ciliary body was observed with no correlation to the degree of reduction of the IOP.

Adult↗