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Biomedical subjects

A Falk

Publications and source records attributed to A Falk.

At least 55 records · Page 3Linked to original sources
PubMed1995

Characterization of rapeseed myrosinase-binding protein.

Myrosinase-binding proteins (MBPs) were purified from seeds of Brassica napus L. (oilseed rape). The proteins were characterized with respect to amino-acid composition, peptide sequence and isoelectric points. Gel electrophoresis and Western blotting of protein extracts from mature seeds showed the existence of at least ten proteins reacting with a monoclonal anti-MBP antibody and ranging in molecular size from 110 to 30 kDa. Proteins other than MBP reacting with the anti-MBP antibody were assigned as myrosinase-binding protein-related proteins (MBPRPs). Two MBPRPs were purified by immunoaffinity chromatography and characterized with respect to partial amino-acid sequence. Sequence identities were found between MBP and MBPRP. Western blot analysis of protein extracts from different tissues of B. napus showed that MBPRP is present in the whole plant, whereas MBP mostly occurs in the mature seed. A double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) was used to investigate the occurrence of MBP and MBPRP in developing seeds of some species in the Brassicaceae family.

Amino Acid Sequence↗
PubMed1995

Modality dependent changes in event-related potentials correlate with specific cognitive functions in nondemented patients with Parkinson's disease.

The relationship between event-related potentials (ERPs) and cognitive functioning was studied in patients with Parkinson's Disease (PD) but without dementia. Auditory and visual stimuli were used; 30 subjects participated in the auditory study and 20 in the visual study. Patient groups did not differ with respect to gender, age, education, illness duration, and level of cognitive functioning. Visual stimuli were 2.3 cpd sinusoidal grating patterns randomly presented in an oddball paradigm (oblique vs. vertical spatial orientation). Auditory stimuli were tones presented at 70 dB SPL at a rate of 1.1/second, also using the oddball paradigm (1.5K vs. 1K tones). All patients were given neuropsychological tests to measure verbal fluency, memory, visual spatial perception, and abstract reasoning. P300 and N200 abnormalities correlated with a number of these measures, such that longer ERP latencies were related to lower scores on tests of cognitive functioning. Patterns of results suggest that auditory and visual ERPs correlate with different subsets of neuropsychological functions in nondemented PD patients and that N200 may provide a new metric for clinical use.

Cognition↗
PubMed1995

CT data acquisition as a basis for modern diagnosis and therapy in maxillofacial surgery.

More than 20 years after its introduction computed tomography has become a routine method in the diagnostic work-up of traumatic and neoplastic disorders in maxillofacial surgery. Short acquisition times of 1 sec per image reduce motion artifacts and permit increased numbers of patient examinations. Different reconstruction algorithms allow specific evaluation of either osseous or soft tissue structures. By adjusting window center and window width the 2048 attenuation values can be transformed into the visible gray scale. Single sequential slices--as employed in routine diagnosis of tumor patients--still yield the highest image quality. Fast volume data acquisition associated with spiral scanning proves to be of special benefit in trauma patients. The resulting data set can be used for reconstruction of single slices, 2-dimensional (2D) reformated images in all planes and 3D surface rendering.

Artifacts↗
PubMed1995

Expression of a zeatin-O-glucoside-degrading beta-glucosidase in Brassica napus.

A beta-glucosidase was purified from seeds of Brassica napus L. (oilseed rape). The 130-kD native enzyme consisted of a disulfide-linked dimer of 64-kD monomers. Internal amino acid sequences were used to construct degenerate primers for polymerase chain reaction-mediated cloning of cDNA for the enzyme. One nearly full-length and one partial beta-glucosidase-encoding cDNA clone were isolated and sequenced. Southern hybridization showed that beta-glucosidase is encoded by a small gene family in B. napus. Northern hybridization showed that the genes are expressed in the seed, with a low degree of expression in other tissues. In the seed, the expression started at 30 days after pollination (DAP), with the highest expression at 40 DAP. The size of the transcript was approximately 1900 nucleotides. In situ hybridization to developing seeds of B. napus showed that the beta-glucosidase expression started at 30 DAP around the provascular tissue in the embryo axis. In the cotyledons, mRNA initially accumulated around the provascular tissues but was detected first at 35 DAP. At 40 DAP, expression occurred in most parts of the seed. In situ hybridization also detected beta-glucosidase mRNA in shoots, young roots, and the basal part of the hypocotyls. Zeatin-O-glucoside was identified as a natural substrate for B. napus beta-glucosidase.

Amino Acid Sequence↗
PubMed1994

Leukotriene receptor antagonism prevents lung protein leakage and hypoxaemia in a septic cat model.

Products of the arachidonic acid cascade have been found to play an important role in the pathophysiology in experimental shock and in ARDS. The effect of cysteinyl-leukotriene (cLT) blockade on the development of respiratory failure during septic shock was examined. Ventilated cats received an infusion of Escherichia coli bacteria. Pretreatment was given with diethylcarbamazine (DEC), a leukotriene synthetase inhibitor, or a new potent cLT receptor antagonist, ICI 198,615. With a gamma camera, the distributions of plasmatransferrin radiolabelled with indium-113m chloride (113mIn) and erythrocytes radiolabelled with technetium-99m (99mTc) were measured over the lungs. A normalized slope index (NSI) reflecting protein leakage, based on the transferrin extravasation, was calculated. In the nonseptic control group (n = 7) NSI was 4.4 x 10(-4) +/- 0.7 x 10(-4).min-1 (mean +/- SEM). Unpretreated septic animals (n = 7) showed a protein leakage after bacterial infusion, with a NSI of 34 +/- 3.5 x 10(-4).min-1. Pretreatment with DEC (n = 6) significantly reduced NSI to 16 +/- 1.5 x 10(-4).min-1. In the group pretreated with ICI 198,615 (n = 8), NSI was 9 +/- 1.2 x 10(-4).min-1. Arterial oxygen tension (PaO2) remained at baseline level of 20 +/- 1.0 kPa during the experimental period in both the nonseptic control group and the ICI 198,615 pretreated group. In the unpretreated septic group, PaO2 fell progressively from a preseptic value of 21 +/- 0.9 to 12 +/- 1.5 kPa after 3 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1993

Characterization of a Brassica napus myrosinase pseudogene: myrosinases are members of the BGA family of beta-glycosidases.

Myrosinase isoenzymes are known to be encoded by two different families of genes denoted MA and MB. Nucleotide sequence analysis of a Brassica napus genomic clone containing a gene for myrosinase revealed it to be a pseudogene of the MA family. The gene spans more than 5 kb and contains at least 12 exons. The exon sequence of the gene is highly similar to myrosinase cDNA sequences. However, the gene displays three potential or actual pseudogene characters. Southern blot analysis using probes from the 3' portions of the genomic and B. napus MA and MB cDNA clones showed that MA type myrosinases are encoded by approximately 4 genes, while MB type myrosinases are encoded by more than 10 genes in B. napus. Northern blots with mRNA from seeds and young leaves probed with the MA- and MB-specific probes showed that the MA and MB myrosinase gene families are differentially expressed. Myrosinases are highly similar to proteins of a beta-glycosidase enzyme family comprising both beta-glycosidases and phospho-beta-glycosidases of as diverged species as archaebacteria, bacteria, mammals and plants. By homology to these beta-glycosidases, putative active site residues in myrosinase are discussed on the basis of the similarity between beta-glycosidases and cellulases.

Amino Acid Sequence↗
PubMed1993

Catecholamines induce alterations of distribution and activity of human natural killer (NK) cells.

Catecholamines have been suggested to be responsible for altered cellular immunity after stress. This study was performed to determine the effects of adrenaline and noradrenaline on lymphocyte subpopulations and NK cell functions. Subjects were given a subcutaneous injection of either NaCl, adrenaline (5 micrograms/kg), or noradrenaline (10 micrograms/kg). Catecholamine concentrations, subsets of peripheral blood lymphocytes, NK activity, and antibody-dependent cellular cytotoxicity (ADCC) were analyzed before (baseline) and 5, 15, 30, 60, and 120 min after injection. There were no differences between groups in the distribution of CD2+ and CD8+ lymphocytes over time. However, CD3+ and CD4+ T cells decreased significantly 5 to 60 min after injection of adrenaline. In contrast, NK cell numbers (CD16+, CD56+) increased significantly 5 min after injection of adrenaline and noradrenaline, reached the highest values 15 to 30 min postinjection, and subsequently declined to baseline values 60 (noradrenaline) and 120 (adrenaline) min, respectively, after injection. Similar alterations for NK activity and ADCC were observed after administration of both catecholamines. These data suggest that both sympathetic-adrenal hormones are similarly potent modulators of natural immunity and provide further evidence that catecholamines might be responsible for the observed alterations in immune functions after phases of acute stress.

Adult↗
PubMed1993

Differential expression of myrosinase gene families.

In mature seeds of Brassica napus three major and three minor myrosinase isoenzymes were identified earlier. These myrosinases are known to be encoded by at least two different families of myrosinase genes, denoted MA and MB. In the work described in this paper the presence of different myrosinase isoenzymes in embryos, seedlings, and vegetative mature tissues of B. napus was studied and related to the expression of myrosinase MA and MB genes in the same tissues to facilitate future functional studies of these enzymes. In developing seeds, myrosinases of 75, 73, 70, 68, 66, and 65 kD were present. During seedling development there was a turnover of the myrosinase pool such that in 5-d-old seedlings the 75-, 70-, 66-, and 65-kD myrosinases were present, with the 70- and 75-kD myrosinases predominating. In 21-d-old seedlings the same myrosinases were present, but the 66- and 65-kD myrosinase species were most abundant. At flowering the mature organs of the plant contained only a 72-kD myrosinase. MA genes were expressed only in developing seeds, whereas MB genes were most highly expressed in seeds, seedling cotyledons, young leaves, and to a lesser extent other organs of the mature plant. During embryogenesis of B. napus, myrosinase MA and MB gene transcripts started to accumulate approximately 20 d after pollination and reached their highest level approximately 15 d later. MB transcripts accumulated to about 3 times the amount of MA transcripts. In situ hybridization analysis of B. napus embryos showed that MA transcripts were present predominatly in myrosin cells in the axis, whereas MB genes were expressed in myrosin cells of the entire embryo. The embryo axiz contained 75-, 70-, and 65-kD myrosinases, whereas the cotyledons contained mainly 70- and 65-kD myrosinases. Amino acid sequencing revealed the 75-kD myrosinase to be encoded by the MA gene family. The high degree of cell and tissue specificity of the expression of myrosinase genes suggests that studies of their transcription should provide interesting information concerning a complex type of gene regulation.

Amino Acid Sequence↗
PubMed1993

Lung protein leakage in feline septic shock.

The aim of the present study was to explore lung microvascular leakage of protein and water in a feline model of septic shock, using a double isotope technique with external gamma camera detection and gravimetric lung water measurements. The experiments were performed on artificially ventilated cats. One group of cats (n = 8) was given an infusion of live Escherichia coli bacteria, and another group (n = 5) served as a control group receiving saline. Plasma transferrin was radiolabeled in vivo with indium-113m-chloride, and erythrocytes were labeled with technetium-99m. The distribution of these isotopes in the lungs was continuously measured with a gamma camera. A normalized slope index (NSI) was calculated, indicative of the transferrin accumulation corrected for changes in local blood volume that reflect protein leakage. In the septic group there was a protein leakage after bacterial infusion, with a NSI of 39 x 10(-4) +/- 5 x 10(-4) min-1 (mean +/- SEM), and the PaO2 diminished from 21 +/- 1 to 9.5 +/- 1 kPa. In control cats a slight protein leakage with a NSI of 9 +/- 10(-4) +/- 2 x 10(-4) min-1 was detected, probably caused by the operative procedure, but PaO2 did not change. Wet-to-dry-weight ratios of postmortem lungs were not significantly different between the groups. It was concluded that an intravenous infusion of live E. coli bacteria induces a lung capillary protein leakage without increased lung water and a concomitantly disturbed gas exchange.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

MR imaging of the knee: can changes in the intracapsular fat pads be used as a sign of synovial proliferation in the presence of an effusion?

OBJECTIVE: Synovial proliferation is difficult to detect on MR images when joint effusions are present. The objective of this study was to assess the efficacy of MR changes in intracapsular fat pads (prefemoral, quadriceps, Hoffa's) as a sign of synovial proliferation in patients with knee effusions. MATERIALS AND METHODS: MR images were obtained in 70 patients with knee effusions. An effusion was considered present if the suprapatellar bursa was distended 1 cm in anterior to posterior diameter on T2-weighted sagittal images. The experimental group consisted of 32 patients with proliferative effusions (effusions associated with synovial proliferation) diagnosed on the basis of histologic or microbiologic data or strict rheumatologic criteria. This group comprised 11 patients with pigmented villonodular synovitis, six with rheumatoid arthritis, one with psoriatic arthritis, three with hemosideric arthritis, and 11 with septic arthritis. The control group comprised 38 subjects with knee effusions who had no arthroscopic evidence of synovial proliferation. After determining the MR criteria of proliferative effusion, two observers who had no knowledge of these cases evaluated abnormalities of the intracapsular fat pads seen on sagittal intermediate-weighted midline MR images. RESULTS: Characteristic changes in the fat pads were noted on MR images in patients with proliferative synovial effusions. Scalloping or truncation of the prefemoral fat pad was 77% sensitive and 95% specific as a predictor of proliferative effusion. Defects and displacement of Hoffa's fat pad had a sensitivity of 57% and a specificity of 99%, and nonvisualization or irregular margins of the quadriceps fat pad had a sensitivity of 61% and a specificity of 100%. CONCLUSION: Characteristic changes in intracapsular fat pads seen on MR images of patients with proliferative effusions can help distinguish these patients from those with effusions without synovial proliferation.

Adipose Tissue↗
PubMed1992

The glucosinolate-degrading enzyme myrosinase in Brassicaceae is encoded by a gene family.

A full-length cDNA clone (MB3) and three partial clones (MA1, MB1 and MB2) which encode myrosinase (thioglucoside glucohydrolase, EC 3.2.3.1) were isolated from a Sinapis alba (white mustard) cDNA library. Nucleotide sequence analysis of these clones revealed that they are encoded by a gene family. Southern blot analysis with gene-specific probes showed that the gene family consists of a least two subfamilies (MA and MB) each with several members both in S. alba and in Brassica napus (oilseed rape). In Arabidopsis thaliana (wall cress) only three myrosinase genes seem to be present. Northern blot analysis indicated that all the myrosinase mRNA species have the same size, approximately 1.95 kb.

Amino Acid Sequence↗
PubMed1992

Renal elimination of verbenols in man following experimental alpha-pinene inhalation exposure.

The renal elimination of verbenols after experimental exposure to (+) and (-)alpha-pinene was studied in humans following exposure to 10, 225, and 450 mg.m-3 terpene in an exposure chamber. The pulmonary uptake was about 60%. About 8% was eliminated unchanged in exhaled air. Depending on the exposure level, about 1%-4% of the total uptake was eliminated as cis- and trans-verbenol. Most of the verbenols were eliminated within 20 h after a 2-h exposure. The renal excretion of unchanged alpha-pinene was less than 0.001%.

Adult↗
PubMed1992

Job strain and mortality in elderly men: social network, support, and influence as buffers.

The aim was to investigate whether job strain affects mortality in a representative population of elderly men, and whether social network and social support outside the workplace can buffer the negative health effects of job strain. A higher relative mortality risk (RR) was found among men exposed to job strain (RR = 1.7). The combination of exposure to job strain and seven different measures of weak social network and social support was associated with a further increased RR ranging from 2.1 to 4.6.

Aged↗
PubMed1992

Knee effusion: normal distribution of fluid.

Although visualization of articular fluid on MR images of the knee is common, no specific MR criteria that enable assessment of the quantity of the effusion have been established. We performed MR of three cadaveric knee specimens after the instillation of increasingly large volumes of fluid and studied the distribution of the fluid. When 4 ml of fluid was injected, the anteroposterior diameter of the suprapatellar recess was 4 mm on midline sagittal MR images and 10.0-12.5 mm on lateral sagittal MR images, corresponding to the usual routine radiographic criteria for a knee effusion.

Humans↗
PubMed1992

The prevalence of diabetes mellitus and other risk factors of atherosclerosis in bradycardia requiring pacemaker treatment.

258 patients with pacemakers (PM) were examined retrospectively; 126 (48.8%) had second- or third-degree av-block (AVB), 43 (16.7%) atrial fibrillation with bradycardia (AFB), 63 (24.4%) sick sinus syndrome (SSS) and 26 (10.1%) other indications (OI). Control persons (CP) of same age and sex with regular sinus rhythm were recruited from in-patients of our hospital. Diabetes was found in 127 (49.2%) of PM (of adult onset only) and in 99 (38.4%) of CP (3 of juvenile onset; p < 0.025), in 68 (53.9%) of the patients with AVP (p < 0.05), 24 (55.8%) with AFB, 21 (33.3%) with SSS (n.s.) and 14 (53.8%) with OI (n.s.). Obesity was positively correlated concerning the entire PM group, blood pressure and smoking habits showed no correlation, cholesterol and triglycerides were inversely correlated (p < 0.05 up to p < 0.001). Myocardial infarction showed no difference between PM and CP, digitalis and diuretics were taken significantly more often (p < 0.001) by PM. We conclude that diabetes mellitus is a major risk factor for av-block of higher degree and atrial fibrillation with bradycardia, which is not influenced by other, diabetes-related risk factors of atherosclerosis.

Aged↗
PubMed1991

Human exposure to 3-carene by inhalation: toxicokinetics, effects on pulmonary function and occurrence of irritative and CNS symptoms.

Terpenes, especially 3-carene, may irritate the skin and mucous membranes and prolonged exposure may result in allergic contact dermatitis or chronic lung function impairment. The toxicokinetics of 3-carene were studied in human volunteers exposed by inhalation (2 hr 50 W) in an exposure chamber on three occasions. The exposure concentrations were approximately 10, 225, and 450 mg/m3 3-carene. The relative pulmonary uptake was high, approximately 70% for the higher exposure levels. Total uptake increased linearly with increasing exposure. The blood clearance of 3-carene observed in this study, 0.9 liter.kg-1.hr-1, indicates that 3-carene is fairly readily metabolized. About 3% of the total uptake was eliminated unchanged via the lungs while less than 0.001% was eliminated in the urine after the end of exposure. A long half time in blood was observed in the terminal phase which indicates a high affinity to adipose tissues. A statistically significant divergence between ratings of irritation during the high exposure level and during the medium and control levels was observed. The difference in airway resistance after exposure to a high concentration of 3-carene compared to control level was not significant (P = 0.02).

Administration, Inhalation↗
PubMed1991

Distribution of myrosinase in rapeseed tissues.

Immunocytochemical studies on Brassica napus (rapeseed) tissues using a monoclonal antibody against myrosinase (thioglucoside glucohydrolase) showed that the enzyme was only present in a small number of cells. In the developing embryo, scattered myrosinase-containing cells were present in both cotyledons and axis. The enzyme accumulated in these cells during the later stages of seed development, approximately from day 20 until day 40 after pollination. Parallel staining with the immunocytochemical technique and a histochemical method identified these cells as myrosin cells. Myrosinase appeared to be located outside the myrosin grains, although the occasional association with the membrane of the grains also was noted. In leaves, petals, and siliques, scattered parenchyma cells were stained in the mesophyll as well as in the vascular tissue. In young leaves, guard cells also contained myrosinase. The enzyme was also present in xylem cells of the stem.

Journal Article↗