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Biomedical subjects

J Fischer

Publications and source records attributed to J Fischer.

At least 217 records · Page 12Linked to original sources
PubMed1996

Drug-induced lysosomal storage of sulphated glycosaminoglycans.

1. Certain compounds (e.g., the immunomodulator tilorone and congeners) are able to induce lysosomal storage of sulphated glycosaminoglycans (GAG), thus, producing cytological and biochemical alterations reminiscent of the inherited mucopolysaccharidoses. The drug-induced GAG storage has been studied in cultured fibroblasts of several species and in rats, and it is likely to occur also in humans. 2. The cytological hallmarks of GAG storage are enlarged lysosomes congested with material that is intensely stained by cationic dyes. With respect to fixation techniques, one has to keep in mind that the GAGs are highly water-soluble and are leached during conventional fixation and tissue processing. Biochemically, the elevation of GAG contents in tissues and cultured fibroblasts is due to storage of dermatan sulphate, predominantly. 3. The molecular structure of the potent inducers of GAG storage is characterized by a planar tricyclic aromatic ring system that is symmetrically substituted with two side chains of 4-5 sigma bond length, each carrying a protonizable nitrogen atom. The lysosomal storage of GAG is accompanied by lysosomal accumulation of the inducing drug, with the molar ratio of drug to GAG-disaccharide unit amounting to > 1:1. The reversibility of GAG storage is rather slow. 4. The pathogenic mechanisms underlying the drug side effects are discussed and the following hypothesis is put forward: The compounds in question are lysosomotropic weak bases. They get trapped in the acidic lysosomes and accumulate highly there. Physicochemical data suggest that the drugs form complexes with the sulphated GAGs, particularly with dermatan sulphate: The positively charged nitrogen atoms of the drug side chains interact with the negative charges of sulphate and carboxy groups of the GAGs, thereby crosslinking at least two GAG helices. Moreover, the interlinking drug molecules form parallel stacks resulting from interaction of the aromatic pi-electrons of the planar ring systems. This further stabilizes the complexes. The GAGs within the complexes are thought to be resistant to the degrading lysosomal enzymes. 5. Drug-induced GAG storage has not been directly demonstrated in man. Yet, clinical reports on keratopathy and basophilic cytoplasmic inclusions in blood lymphocytes of tilorone-treated patients suggest that this drug side effect may also occur in man.

Adjuvants, Immunologic↗
PubMed1996

Three cases of hindbrain herniation in adults with comments on some diagnostic difficulties.

In discussing the clinical features and surgical treatment of adult patients with Arnold Chiari deformity type I the authors focus on the differential diagnosis from demyelinating disease and present three illustrative cases. Out of 118 patients initially diagnosed as having demyelinating disease and admitted to our hospital between December 1991 and April 1993, three were subsequently found to have the Arnold Chiari deformity on MRI. The delay until correct diagnosis amounted to 10, 16 and 32 years, respectively. Our study stresses the diagnostic importance of MRI of the craniocervical area in cases of unexplained neurological symptoms and external signs of dysplasia. Accurate examination, early diagnosis and selection of proper surgical management can alleviate severe symptoms in many instances and prevent neurological complications.

Adolescent↗
PubMed1996

Osteoneogenesis and its influencing factors during treatment with the Ilizarov method.

The radiographs of 57 patients who had undergone 58 callus distractions and 13 epiphyseal distractions were evaluated. During the course of treatment, the density of the distraction areas on radiographs was measured in total and along the medial, lateral, ventral, and dorsal margins using a digital radiograph processing system. The densities of the whole distraction length were correlated to the following parameters: age of patient, start of distraction after corticotomy, mean distraction speed, mean amount of weight load during the period of distraction and consolidation, location of corticotomy (distal femoral metaphysis versus the proximal tibial one), and diclofenac medication. Except for the location of corticotomy and the diclofenac medication, the density was influenced by all these parameters. Age of the patient and weight load were the most important parameters. Patients with leg shortening caused by poliomyelitis and a patient with a shortened leg after amniotic strangulation showed a slower rise of the density trend curve on radiographs than the other patients. When comparing the different regional density curves, a significant gradual density decrease could be observed from the medial to the lateral side in the femur, from lateral to medial in the tibia, and from the dorsal to the ventral side in both bones. The respective differences between lateral and medial density, and between dorsal and ventral density, were significantly higher in cases of callus distraction than in cases in which epiphyseal distraction had been used. The amount of bone regeneration varied regionally primarily because of the inhomogeneous soft tissue covering of the bone and the impairment of its local blood supply by the surgical exposure for the corticotomy. The clinical relevancy of the various parameters for osteoneogenesis is discussed in this article.

Adolescent↗
PubMed1996

PCR reaction and dot-blot hybridization to monitor the distribution of oral pathogens within plaque samples of periodontally healthy individuals.

The purpose of this study was to determine the distribution of the putative periodontal pathogens Prevotella intermedia, Prevotella nigrescens, the three oral Capnocytophaga species (C. ochracea, C. sputigena, C. gingivalis), as well as Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans in plaque samples of periodontally healthy individuals. We chose a newly developed 16S rDNA directed polymerase chain reaction (PCR) and a previously described dot-blot hybridization assay to detect, differentiate, and quantify these bacteria directly in clinical samples. The subjects of these investigations were 66 sulcus fluid samples from 17 children (ages 3 to 5) attending a kindergarten, 48 sulcus fluid samples from 12 children (ages 9 and 10) from a primary school, and 25 subgingival plaque samples isolated from 6 different periodontally healthy dental students (ages 24 to 27). We were able to demonstrate the presence of P. nigrescens in 54 (kindergarten: 5; primary school: 33; students: 16) samples by PCR and quantified it by dot-blot hybridization. In addition, we found C. ochracea in 12 (kindergarten: 2; primary school: 10) samples by PCR reaction only. The other tested bacterial species were absent by the methods used. Furthermore we confirmed the specificity of our P. nigrescens-PCR in selected samples by enzyme electrophoresis.

Adult↗
PubMed1996

Ventral hernia repair with simultaneous panniculectomy.

The repair of a ventral hernia in an obese patient presents an interesting clinical challenge. We retrospectively reviewed the charts of 55 patients who, over a 12-year period from 1983 to 1995, concomitantly underwent both ventral herniorrhaphy and panniculectomy or abdominoplasty. In six of 55 patients, the hernia was recurrent. Forty-six patients had primary abdominal wall hernias or diastasis recti. Nineteen of 55 patients had weight greater than 200 lbs. This last subset of patients had a significantly higher incidence of complications, such as seroma, cellulitis, and persistent wound drainage. In our 55 patients, we experienced only two hernia recurrences (3.6%) during an average patient follow-up of 53 weeks. From this experience, we believe that simultaneous ventral hernia repair and panniculectomy is a safe and efficacious approach to these two problems so commonly found in the obese patient. Patients with a preoperative weight greater than 200 lbs can be expected to have a greater risk of wound complications. In all cases, the wounds eventually healed with no long-term sequelae.

Adipose Tissue↗
PubMed1996

[Retroperitoneoscopic lumbar symathectomy].

During the period between August 1995 and February 1996 at the Second Surgical Clinic of the Faculty Hospital in Olomouc 12 retroperitonescopic lumbar sympathectomies were performed on account of different indications. The authors present an elaborate technique of access into the retroperitoneum and their own technique of lumboscopic sympathectomy. The success of the method was evaluated clinically and by histological evidence of sympathetic ganglia in the collected material. Retroperitoneoscopic lumbar sympathectomy is considered a gentle and safe method which can be used also in other patients where the risk of open surgery would be excessive.

Adult↗
PubMed1996

[Stereotaxically guided versus ultrasound guided surgery--a comparative report of experiences].

Localisation and approach are the keys of surgery on brain tumours. Apart from the up and coming neuronavigational devices, stereotactical and ultrasound guidance are well established methods in locating intracranial tumours and in selecting the optimal approach for resection. Nevertheless it is not clear, which guidance tool is more practicable in the daily routine. Both methods have been used in our department since 1989. During the last six and half years we have operated on 1314 patients suffering from intracranial tumours. In 148 cases we have used either stereotactical (n = 37) or ultrasonic (n = 111) intraoperative guidance. The performing surgeon had documented ease of use, accuracy and users acceptance of the chosen guidance tool. The data were summarised together with the patients history and images in to a descriptive report. Since 1992 we noted a steady increase in guiding operations from 4% to 24%, mainly due to the more frequent use of ultrasound guidance. Saving time, easy handling, accuracy and plausible guidance with real time pictures have been the major advantages in favouring ultrasound guidance. Additionally, the freedom in choosing the appropriate approach seems to be essential. To achieve full advantage of all these benefits, experience and individual expertise are necessary. Conversely, the high accuracy of stereotactic guidance is not within the reach of the ultrasound, which is sufficient to guide the operation. According to our experiences, we recommend intraoperative ultrasound as an easy guiding tool. Except a few cases, this guiding tool seems to be superior to the stereotactic localisation of intracranial lesions.

Brain Mapping↗
PubMed1995

Tilorone-induced lysosomal storage of glycosaminoglycans in cultured corneal fibroblasts: biochemical and physicochemical investigations.

Tilorone (2,7-bis[2-(diethylamino)ethoxy]-fluoren-9-one) and several other bis-basic compounds are known to induce lysosomal glycosaminoglycan (GAG) storage. The responsible pathomechanism has not been elucidated yet. The assumption of an unspecific disturbance of lysosomal proenzyme targeting due to elevation of endosomal pH is opposed by the hypothesis of formation of a complex between tilorone and GAGs within the lysosomes, which renders GAGs indigestible to glycosidases. In cultures of bovine corneal fibroblasts the amounts of intracellular GAGs [dermatan sulphate (DS), heparan sulphate (HS) and chondroitin sulphate (CS)] were quantified. The fibroblasts were exposed to tilorone (5 microM), which was found to be readily taken up by the cells and to be accumulated within acidic compartments to finally achieve millimolar concentrations. Under these conditions the GAG storage is predominantly due to the accumulation of DS; however, the DS secretion into the culture medium was not affected. The HS accumulation was much less pronounced, accounting only for 3% of total GAG storage. Ammonium chloride (10 mM), which is known to diminish lysosomal enzyme activity by interfering with the mannose 6-phosphate receptor-mediated transport, prevents both HS and DS breakdown. By means of NMR spectroscopy it was shown that tilorone itself tends to display a concentration-dependent aggregation which was enhanced in the presence of GAGs. The diethylamino groups of tilorone interact physicochemically with DS, and to a smaller extent with HS, but not with chondroitin 4-sulphate. Thus, the strength of the interaction between tilorone and the different GAGs in vitro correlates with the potency of tilorone to inhibit the breakdown of the individual GAGs in cultured bovine fibroblasts. The results support the hypothesis of a specific interaction between tilorone and particular GAGs, rendering these resistant to enzymic degradation.

Ammonium Chloride↗
PubMed1995

Purification, cDNA cloning and characterization of proteinase B, an asparagine-specific endopeptidase from germinating vetch (Vicia sativa L.) seeds.

Proteinase B, an asparagine-specific endopeptidase, has been purified from germinating vetch (Vicia sativa L.) seeds. The final preparation consists of two enzymically active proteins with molecular masses of approximately 39 kDa and 37 kDa. Synthetic substrates were used to confirm cleavage specificity of the proteinase B preparation. As expected, the enzyme cleaves the substrates at the C-terminal side of Asn residues. The octapeptide ETRNGVEE was digested most efficiently. When Gly was replaced by Ile or Glu, cleavage took place with lower efficiency. Polyclonal antibodies displayed both proteins in cotyledon extracts of germinated vetch seeds. In addition, a strong cross-reacting protein band was found in cotyledon extracts of developing seeds, indicating the presence of a very similar enzyme during seed development. cDNA clones encoding proteinase B precursor have been obtained on the basis of the N-terminal amino acid sequence DDDFEGTRWAILLAGS, by means of the polymerase chain reaction. The cDNA clones contain an open reading frame of 1479 bp encoding a polypeptide of 493 amino acids. The precursor displayed 59% sequence identity to the cDNA-derived amino acid sequence of a vacuolar Asn-specific enzyme from the developing castor beam endosperm which is thought to catalyze the post-translational processing of pro-proteins into the mature forms. Proteinase B is synthesized de novo during seed germination. The results of Southern-blot analyses suggested that there are at least two genes for proteinase B.

Amino Acid Sequence↗
PubMed1995

Low-dose (7.5 mg) oral methotrexate reduces the rate of progression in chronic progressive multiple sclerosis.

A randomized, double-blinded, placebo-controlled, clinical trial of low-dose, weekly, oral methotrexate was performed in 60 patients with clinically definite chronic progressive multiple sclerosis (MS) attending a referral-based outpatient MS clinic. Study patients were 21 to 60 years old with a disease duration of longer than 1 year. Patients' Expanded Disability Status Scale scores were 3.0 to 6.5 (ambulatory with moderate disability). Patients were first stratified by Expanded Disability Status Scale scores, 3.0 to 5.5 and 6.0 to 6.5, and then were randomized to receive methotrexate or placebo treatment. Treatment consisted of weekly, oral, low-dose (7.5 mg) methotrexate or identical placebo for 2 years, followed by observation for as long as 1 year. A composite outcome measurement instrument was used and consisted of (1) Expanded Disability Status Scale, (2) ambulation index, (3) Box and Block Test, and (4) 9-Hole Peg Test. Failure of therapy was indicated by a designated change that was sustained for more than 2 months in one or more components of this composite measure. Significantly less progression of impairment as measured by validated tests of upper-extremity function was observed in the methotrexate treatment group in the absence of clinically significant toxicity. We conclude that low-dose, weekly, oral methotrexate offers a new, relatively nontoxic treatment option for patients with chronic progressive MS.

Administration, Oral↗
PubMed1995

Influence of cAMP-effector-agonists on the synthesis of metallothionein in rat primary hepatocytes.

The model of rat primary hepatocytes incubated in DMEM/F12 (Ham) medium was used for studying the influence of the cAMP-effectors epinephrine (100 microM), norepinephrine (100 microM), glucagon (1 microM) and isoproterenol (1-1000 microM) as well as the synthetic cAMP-analogon dibutyryl-cAMP on the metabolism of metallothionein. Liver parenchymal cells isolated by a two-step collagenase perfusion were incubated with DMEM/F12 containing 5% (v/v) fetal calf serum (FCS) and 20 microM zinc in Petri dishes. Experiments were initiated after a 24 h equilibration period by adding the agonists for 18 h. MT in hepatocyte homogenates was quantified by the 109Cd-hemoglobin-binding assay. Cell viability was assessed by the activity of the cytosolic enzyme lactate dehydrogenase (LDH) liberated into the culture medium and by trypan blue exclusion. Isoproterenol and glucagon produced a significant increase of cytosolic MT about 50%. In contrast, incubation with epinephrine and norepinephrine did not lead to any significant effects in the amount of hepatic metallothionein. Simulating the influence of cAMP by dibutyryl-cAMP (500 microM) did not affect the content of hepatic metallothionein. To examine transcriptional and translational regulatory effects supplementation of cycloheximide (0.1-500 microM) and actinomycin D (0.1-100 microM) showed a total inhibition of the agonist induced amounts. Particularly in combination with isoproterenol low LDH activities reflected a high viability of hepatocytes. In conclusion, in primary hepatocyte cultures cAMP-mobilizing-agonists like isoproterenol and glucagon indicate an independent effect on the MT-metabolism. This is possibly due to the de novo synthesis of the protein because suppression by actinomycin D can be observed. However, cAMP-effectors do not seem to be involved in the induction of metallothionein because theophylline and dibutyryl-cAMP did not affect MT-metabolism by suppressing the phosphodiesterase or by stimulating the cAMP-cascade.

Analysis of Variance↗
PubMed1995

Ultrastructural study of substance P receptors in the dorsal horn of the rat spinal cord using monoclonal anti-complementary peptide antibody.

A monoclonal antibody directed against a peptide (PS5) specified by RNA complementary to the mRNA coding for substance P (SP), was used to label SP receptors in the rat spinal cord as demonstrated by light and electron microscopy. An immunocytochemical method (avidin-biotin-peroxidase) was used on vibratome sections from rats perfused with paraformaldehyde. Immunoreactivity was observed principally in the two superficial layers of the dorsal horn, in lamina X and the region of motoneurons. The labeling was absent when the antibody was preincubated with the complementary peptide (PS5) used as immunogen. Competition between the anti-complementary peptide antibody and different ligands was tested by preincubation of tissue sections with the ligand in the presence of peptidase inhibitors before addition of the antibody. A specific agonist (SP) or antagonist (spantide, RP 67580) at 10(-6)M led to total absence of labeling. These results indicate that under our experimental conditions, the anti-complementary peptide antibody recognizes a SP binding site in the rat spinal cord. Electron microscopic study of the two superficial laminae of the dorsal horn showed that immunolabeling was mainly localized extracellularly at apposing neuronal plasma membranes. It was mostly associated with axodendritic or axosomatic appositions. Occasionally labeling was observed between two axon terminals. In all cases, these appositions were non-junctional. Generally, neuronal processes involved in these appositions did not contain large granular vesicles. These observations suggest that SP may act in a diffuse, nonsynaptic manner probably on targets distant from SP release sites.

Amino Acid Sequence↗
PubMed1995

Identification of the valine 408 to methionine mutation in the LDL receptor in a Greek patient with homozygous familial hypercholesterolemia.

We have identified the cytosine to thymine change in the codon for amino acid 408 which causes valine to be replaced by methionine in exon 9 of the LDL receptor gene in a 12-year-old Greek boy living in Germany, with homozygous familial hypercholesterolemia, by using polymerase chain reaction-amplified genomic DNA and subsequent restriction digestion. Homozygosity was confirmed by direct DNA sequencing. The mutation was present in both his parents, and his brother, grandmother, uncle and cousin. Six restriction fragment length polymorphisms of the LDL receptor gene were used to determine the haplotype of the defective allele. The haplotype was different from the one reported earlier in African Afrikaners and from Holland. We conclude that the mutation in the Greek boy probably occurred as an independent mutation. Because the parents are from different areas in Greece, this mutation may be common in Greeks.

Base Sequence↗
PubMed1995

Multiple sclerosis progression in a natural history study: predictive value of cerebrospinal fluid free kappa light chains.

OBJECTIVES: To determine the relationship between baseline CSF immunologic abnormalities and MS disease progression; To determine progression rates in an untreated, recently-diagnosed MS sample using several validated clinical measures. BACKGROUND: CSF immune abnormalities are common in MS but have not been linked to disease progression. DESIGN METHODS: Thirty-six patients with definite (n = 28), probable (n = 2), or possible (n = 6) MS were studied prospectively. Baseline CSF was analyzed for free kappa and lambda light chains, myelin basic protein, IgG synthesis rate, and IgG index. MS patients were entered into the study within 5 years of symptom onset and examined semiannually for as long as 53.4 months (median length of follow up 38.9 months). MS progression was defined as sustained worsening on the following clinical measurement instruments: the Expanded Disability Status Scale (EDSS), the Ambulation Index (AI), the 9 Hole Peg Test (9HT) and the Box and Blocks test (BBT). Kaplan-Meier estimates of disease progression were calculated and the relationship between baseline CSF values and disease progression was determined using Cox proportional hazards regression models. RESULTS: By 36 months, 33% (95% CI = 10.3, 55.7) of patients had progressed on EDSS and 49.7% (95% CI = 27.7, 71.7) had progressed on at least one of the outcome measures. Patients with CSF free kappa chain levels in the upper quartile had a significantly higher risk of progression on EDSS (Hazard Ratio 3.78; p = 0.04) and 9HT (Hazard Ratio 10.77, p = 0.04). CONCLUSIONS: In this study, CSF free kappa light chains predicted subsequent physical deterioration in prospectively evaluated MS patients. If this is confirmed by larger studies, then CSF free kappa light chains could serve as a target for intervention in therapeutic trials.

Adolescent↗
PubMed1995

[Possible applications of ultrasound in corticotomy-callus distraction].

Sonographic examination can yield additional information in the course of corticotomy-callus distraction. Hence, we focus on individual slices--which are different from the standardised ultrasound examination of the skeleton system--in the area of the corticotomy-callus distraction. In ultrasound examination the structure of corticalis in the field of corticotomy is scanned circularly. Depending on the point of time of the corticotomy between the structure of corticalis, the callus can be visualised sonographically. The callus distraction can be divided into three stages: I. echo-poor structure between the two ends of the corticalis, II. echo-rich structure between the two ends of the corticalis, III. area of corticalis in the area of distraction with (III a), visualised without (III b) break. The described method is an additional low-cost imaging procedure in diagnosis, for the patient free of radiation and stress, which can yield additional information during and after completed callus distraction (question of permissible emotional stress). The examination is reproducible. The x-ray-controls in the course of time are mandatory, because the sonographic examination cannot judge reliably the deviation of the axis in the area of callus distraction.

Adolescent↗