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Biomedical subjects

M Kraft

Publications and source records attributed to M Kraft.

At least 109 records · Page 6Linked to original sources
PubMed1995

Synovial fibroblasts as accessory cells for staphylococcal enterotoxin-mediated T-cell activation.

Rheumatoid arthritis (RA) is thought to be the result of T-cell-mediated autoimmune phenomena. So far, a critical autoantigen has not been identified. Recently, superantigens have been implied in the pathogenesis of RA. In the present study it was tested whether major histocompatibility complex (MHC) class II-positive synovial fibroblast cells (SFC) function as superantigen-presenting cells. SFC were stimulated with interferon-gamma (IFN-gamma) to express class II antigens; then they were cultivated in the presence of T cells with or without staphylococcal enterotoxins (SE). T-cell activation was measured as proliferation and interleukin-2 (IL-2) production. Depending on the dose and type of SE, activation of T-cell clones and also of peripheral T cells was seen. T-cell activation was inhibited by antibodies to MHC class II antigens and also by antibodies to intracellular adhesion molecule type-1 (ICAM-1). The data suggest that class II-positive SFC have the capacity to serve as accessory cells for superantigen-mediated T-cell activation. Thus SFC may participate in the propagation of a T-cell dependent immune response.

Antigen-Presenting Cells↗
PubMed1994

Nicotinic acetylcholine receptor subunits expressed in rat cochlea detected by the polymerase chain reaction.

Poly(A)+ RNA was extracted from rat cochleae using guanidinium thiocyanate and oligo(dT)-cellulose, and converted into cDNA by reverse transcriptase using an oligo(dT) primer. Oligonucleotides complementary to conserved 5' and 3' regions of alpha and beta subunits of the neuronal nicotinic acetylcholine receptor subunit (nAChR) family were then used as primers to screen the cochlear cDNA via the polymerase chain reaction (PCR) procedure. PCR products of approximately 900 bp length, purified by agarose gel electrophoresis, were nick translated to produce [32P]-dCTP labelled probes for Southern Blot screening of nAChR cDNAs. Of the four alpha and three beta subunits screened, only alpha 5 and beta 4 nAChR cDNAs hybridized. The alpha 5 PCR product was cloned and sequenced and proved to be identical to published sequence for alpha 5. The detection of alpha 5 and beta 4 nAChR subunit expression in cochlear tissue supports previous electrophysiological and immunocytochemical evidence for nAChR-mediated centrifugal control of hearing function.

Animals↗
PubMed1994

Blood and bronchoalveolar lavage endothelin-1 levels in nocturnal asthma.

Endothelin-1 (ET-1) is a potent endogenous vasoconstrictor that was recently shown to exhibit bronchoconstrictive properties in vitro. In asthmatic patients, the expression of ET-1 peptide was also shown to be increased in endobronchial biopsies. Thus, we postulated that ET-1 could be higher in subjects with nocturnal asthma. Bronchoalveolar lavage (BAL) fluid levels of ET-1 were measured in 10 subjects with nocturnal asthma and 6 normal volunteers at 0400 h (nighttime groups) and in an additional 7 subjects with nocturnal asthma and 6 control subjects at 1600 h (daytime groups). ET-1 levels were significantly lower in the nighttime asthmatic group (median 39.3 pg/mg protein, 7.3 to 44.0 IQ) than in the nighttime control group (median 77.4 pg/mg protein, 46.8 to 121.9 IQ; p = 0.01) or the daytime asthmatic group (median 56.8 pg/mg protein, 51.6 to 97.4 IQ; p = 0.04). ET-1 levels did not differ significantly between the daytime asthmatic and the daytime control groups or between control groups. Additionally, the overnight reduction in lung function was significantly correlated with lower BAL ET-1 levels (r = 0.57, p = 0.05). These results suggest that ET-1 plays a role in the overnight worsening of asthma and perhaps is more tightly tissue bound, resulting in lower levels of BAL fluid.

Adult↗
PubMed1993

Cryptogenic constrictive bronchiolitis. A clinicopathologic study.

Four women with a chronic respiratory illness characterized by chronic cough, dyspnea, mild to severe physiologic abnormalities, relatively normal chest radiographs, and lack of response to bronchodilators or prednisone were identified and prospectively evaluated. Constrictive bronchiolitis, defined as concentric narrowing of the bronchiolar lumen, mural scarring, smooth muscle hyperplasia, and mucus stasis, was the major histologic finding on open lung biopsy in all cases. Each presented with an illness clinically distinct from asthma, connective tissue disorders, occupational or environmental lung disease, bronchiectasis, diffuse panbronchiolitis, cystic fibrosis, and emphysema. None of the patients smoked cigarettes. None had clinical evidence of a recent viral lower respiratory tract infection. The physical examinations were normal except for rales heard on chest examination in two patients. Chest radiographs showed increased bronchovascular markings in three patients. Lung function was normal in one patient, two of the patients had a reduced diffusing capacity associated with moderate hypoxemia and an obstructive ventilatory defect, and one patient exhibited a mixture of restrictive and obstructive defects. None have experienced significant progression of their disease over 1 to 5 yr of follow-up. However, complete return to normal function did not occur. We hypothesize that patients with the constellation of findings described represent a distinct and definable clinicopathologic entity and further clarifies the spectrum of "small airways disease." Establishing the diagnosis appears important for prognostic and possibly therapeutic reasons.

Adult↗
PubMed1992

Immunological characterization of an immunomodulatory epitope in S-antigen/arrestin with a sequence motif common to tumor necrosis factor alpha.

Some monoclonal antibodies (mAbs) to retinal S-antigen recognize a phylogenetically conserved epitope (S2) in the N-terminal part of the protein. These antibodies have been shown to inhibit the induction of experimental autoimmune uveoretinitis by S-antigen in rats. Using Pepscan method, we localized this epitope on the amino acid (aa) residues 40-50, i.e., PVDGVVLVDPE (peptide S2). MAb binding was confirmed by ELISA, competition-ELISA and dot blot. Other S-antigen peptides with homologies to epitope S2 and peptides exhibiting the pathogenic and T-cell proliferation inducing sites did not bind these mAbs. Epitope S2 displays an immunological crossreactivity with human tumor necrosis factor (TNF) alpha. Recent results indicate that both peptide S2 and a peptide from human TNF alpha (aa residues 31-53) containing the common sequence motif GVxLxD induce TNF alpha production in monocytes. We analyzed the fine structure of the common epitope by studying mAb binding in an amino acid residue exchange experiment.

Amino Acid Sequence↗
PubMed1992

Benign coital headache.

We studied the natural history of patients with a diagnosis of benign coital headache who presented to a private neurological clinic between the years 1978 and 1991. Thirty-two patients (24M, 8F) were invited to participate and 26 patients (83%) responded. The period of follow-up ranged from six months to 14 years (median 6 years). Thirteen patients (50%) had recurrent attacks of coital headache epochs separated by intervals of up to 10 years. Eleven of these patients suffered a concomitant primary headache whereas this was present in only one of those patients without recurrent attacks of coital headache (p < 0.001). In all but one patient, who had a transient blurred vision, the headache was not accompanied by nausea, vomiting, visual disturbances, sensory/motor disturbances, or unconsciousness. We concluded that benign coital headache can be clearly distinguished from headaches due to cerebral aneurysm or arteriovenous malformation rupture. The presence of a concomitant primary headache syndrome is a risk-factor for recurrence of coital headache.

Adult↗
PubMed1992

Abnormal oxygen uptake responses to exercise in patients with mild pulmonary sarcoidosis.

Exercise intolerance and exertional dyspnea are common complaints in patients with sarcoidosis. Although in many cases these complaints are attributable to restrictive or obstructive lung mechanics or inefficiency of pulmonary gas exchange, other processes also may contribute to impairment in exercise function and may not be readily detected or distinguished from problems of lung mechanics on the basis of symptoms or routine laboratory testing. To identify the frequency and etiology of impaired exercise capacity in sarcoidosis patients with mild lung disease, integrative cardiopulmonary exercise testing was performed in 23 patients. Breath-by-breath measurements were made of gas exchange, ventilation, and heart rate. In 9 of 20 evaluable patients, the oxygen uptake (VO2) at the anaerobic threshold was low, and/or the rate of increase of VO2 was abnormal relative to work rate or heart rate, suggesting a defect in cardiocirculatory function. Resting and exercise echocardiography revealed normal left ventricular ejection fractions and wall motion in all nine of these patients, but findings suggestive of right ventricular hypertrophy and/or right ventricular dysfunction were present in five. Abnormal responses of VO2 during exercise are common in patients with sarcoidosis and may be due to subclinical impairment of right-sided cardiac function.

Adult↗
PubMed1991

Occurrence and distribution of non-NMDA glutamate receptor mRNAs in the cochlea.

The expression of mRNAs encoding five putative non-NMDA glutamate receptors was investigated using in situ hybridization with radiolabeled riboprobes. Hybridization was observed in spiral ganglion neurons with probes complementary to mRNA products of the glutamate receptor genes GluR2 and GluR3. No specific hybridization was observed with probes for GluR1, GluR4 or GluR5. The results support the hypothesis that glutamate is the transmitter between cochlear inner hair cells and spiral ganglion neurons, and that it acts via non-NMDA glutamate receptors.

Cochlea↗
PubMed1991

Synthesis, conformational studies, and molecular dynamics calculations of two cyclic tetrapeptides with 17- and 18-membered rings.

Two cyclic tetrapeptides [Boc-cyclo(-Xxx-Pro-Asn-Lys-)OMe (Xxx = Asp or Glu)] were synthesized and investigated by NMR spectroscopy. They were designed in order to mimic the salt bridge found in physalaemin. Isomers of the urethane bond were observed in DMSO solution. The ROESY spectrum allowed the assignment of many signals of the minor isomer of both compounds. Conformational studies based on the temperature gradients of the NH chemical shifts, coupling constants, and ROEs revealed a similar conformation for the Asp analogue as proposed for physalaemin. A beta I turn with Pro and Asn in the corner positions was found for the major isomer. No hydrogen bonds were detected for the major isomer of the cyclic Glu analogue. Molecular dynamics calculations, using the NMR based initial structures, yielded sets of conformations in agreement with the experimental data. It is concluded that the salt bridge in physalaemin is best approximated by a lactam formed from the original amino acids.

Amino Acid Sequence↗
PubMed1990

Analysis of the substrate specificity of tyrosylprotein sulfotransferase using synthetic peptides.

Tyrosylprotein sulfotransferase (TPST) catalyzes the sulfation of proteins at tyrosine residues. We have analyzed the substrate specificity of TPST from bovine adrenal medulla with a novel assay, using synthetic peptides as substrates. The peptides were modeled after the known, or putative, tyrosine sulfation sites of the cholecystokinin precursor, chromogranin B (secretogranin I) and vitronectin, as well as the tyrosine phosphorylation sites of alpha-tubulin and pp60src. Varying the sequence of these peptides, we found that (i) the apparent Km of peptides with multiple tyrosine sulfation sites decreased exponentially with the number of sites; (ii) acidic amino acids were the major determinant for tyrosine sulfation, acidic amino acids adjacent to the tyrosine being more important than distant ones; (iii) a carboxyl terminally located tyrosine residue may be sulfated. Moreover, TPST catalyzed the sulfation of a peptide corresponding to the tyrosine autophosphorylation site of pp60v-src (Tyr-416) but not of a peptide corresponding to the non-autophosphorylation site of pp60c-src (Tyr-527). These results experimentally define structural determinants for the substrate specificity of TPST and show that this enzyme and certain autophosphorylating tyrosine kinases have overlapping substrate specificities in vitro.

Adrenal Medulla↗
PubMed1990

[Shaping of electron radiation fields using homogeneous absorbent materials].

Proof of shielding and forming by absorbers was done in water phantom dosimetrically. Alterations of isodose course were measured in dependence of primary energy, as well as of thickness and density of the absorber materials. Piacryl or aluminium are not suitable for forming of irregular electron fields. They only effect a reduction of therapeutic range. For primary energies of 10.0 less than or equal to MeV less than or equal to E0- less than or equal to 20.0 MeV lead rubber and wood metal are to recommended in a thickness of less than or equal to 10 mm or less than or equal to 8 mm respectively.

Electrons↗
PubMed1989

Asparagine coupling in Fmoc solid phase peptide synthesis.

To investigate side reactions during the activation of side chain unprotected asparagine in Fmoc-solid phase peptide synthesis the peptide Met-Lys-Asn-Val-Pro-Glu-Pro-Ser was synthesized using different coupling conditions for introduction of the asparagine residue. Asparagine was activated by DCC/HOBt, BOP (Castro's reagent) or introduced as the pentafluorophenyl ester. The resulting peptide products were analyzed by HPLC, mass spectrometry and Edman degradation. In the crude products varying amounts of beta-cyano alanine were found, which had been formed by dehydration of the side chain amide during carboxyl activation of Fmoc-asparagine. A homogeneous peptide was obtained by using either side chain protected asparagine derivatives with BOP mediated activation or by coupling of Fmoc-Asn-OPfp. Fmoc-Asn(Mbh)-OH and Fmoc-Asn(Tmob)-OH were coupled rapidly and without side reactions with BOP. For the side chain protected derivatives the coupling was as fast as that of other Fmoc-amino acid derivatives, whereas couplings of Fmoc-Asn-OH proceed more slowly. However, during acidolytic cleavage both protection groups, Mbh and Tmob, generate carbonium ions which readily alkylate tryptophan residues in a peptide. Tryptophan modification was examined using the model peptide Asn-Trp-Asn-Val-Pro-Glu-Pro-Ser. Alkylation could be reduced by addition of scavengers to the TFA during cleavage and side chain deprotection. A homogeneous peptide containing both, asparagine and tryptophan, was obtained only by coupling of Fmoc-Asn-OPfp.

Amino Acid Sequence↗
PubMed1988

[Phenotype of mucopolysaccharidoses. A warning: mucopolysaccharidosis is not called gargoylism!].

In medical practice only mucopolysaccharidosis syndromes presenting with gargoylism are being diagnosed. It must however be mentioned that the most frequent mucopolysaccharidosis, Sanfilippo's disease, and other forms of mucopolysaccharidoses (MPSoses) are not showing gargoylism. Besides normal phenomenology "anthropoid" appearance is the prominent and most common--pithecoid--clinical feature. It is the aim of this publication to point to the fact that the appearance of children is in most of the cases with MPSoses nonpathognomonic and only few of them are undergoing further diagnostic steps concerning specific MPSoses diagnostic. This lead to the postulation that even in the presence of few clinical signs of mucopolysaccharidoses as psychomotor retardation, or anthropoid appearance, or hair changes, a screening must be performed. For this purpose the application of the toluidine blue test is not sufficient, as only quantitative changes are found by the use of this test. At least one dimensional or, better, two dimensional electrophoretic separation of urinary mucopolysaccharides should be performed. This procedure, if giving positive results, must be followed by enzyme studies. Following this scheme seems to be the only possibility to establish early and fair genetic counselling in order to cope with these fatal diseases.

Child↗