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K H Krause

Publications and source records attributed to K H Krause.

At least 91 records · Page 5Linked to original sources
PubMed1990

The calcium signal and neutrophil activation.

The cytosolic free calcium concentration, [Ca2+]i in phagocytic cells (e.g. neutrophils, human leukemic cell line HL-60) is an important determinant of cellular activity. In resting phagocytes [Ca2+]i is low (approximately 100 nM), but in response to occupation of cell surface receptors, it rises to micromolar levels, thereby activating a variety of cellular functions. The increases in [Ca2+]i consist of two components: an immediate that is independent of extracellular Ca2+, and a more delayed that is abolished by the removal of extracellular Ca2+. These two components reflect the involvement of two subcellular structures in intracellular Ca2+ homeostasis: an intracellular Ca2+ store, referred to as the calciosome; and the plasma membrane. The function of the intracellular Ca2(+)-store depends on a Ca2(+)-pump, functionally and immunologically related to the cardiac sarcoplasmic reticulum Ca2(+)-ATPase, a Ca2(+)-storage protein, similar to muscle calsequestrin, and a Ca2(+)-release channel, which is sensitive to inositol 1,4,5-trisphosphate. The Ca2(+)-regulatory function of the plasma membrane depends on a Ca2+ pump, similar to the erythrocyte-type Ca2(+)-ATPase, and a Ca2+ channel; the activity of the Ca2+ channel is closely coupled to phosphatidylinositol turnover.

Calcium↗
PubMed1990

Voltage-dependent and Ca2(+)-activated ion channels in human neutrophils.

To investigate the regulation of membrane voltage and transmembrane ion fluxes in human neutrophils, we studied plasma membrane currents using the whole-cell patch-clamp method. We observed three distinct ion channel currents: (a) a voltage-dependent K+ current, (b) a Ca2(+)-activated K+ current, and (c) a Ca2(+)-activated Cl- current. The voltage-dependent K+ current was found in cells at rest. Its conductive properties suggested an inwardly rectifying channel. The channel was activated at membrane potentials more positive than -60 mV, suggesting that it may determine the resting membrane potential of neutrophils. Activation of neutrophils by the Ca2+ ionophore ionomycin led to an increase in whole-cell K+ and Cl- currents. The Ca2(+)-activated K+ channel differed from the voltage-dependent K+ channel because it was insensitive to voltage, because it rectified outwardly, and because the voltage-sensitive K+ channel was Ca2(+)-independent. The Ca2(+)-activated Cl- channel showed outward rectification and no apparent voltage dependency. The Ca2(+)-activated K+ and Cl- channels may play a role in cell volume homeostasis and/or cellular activation.

Calcium↗
PubMed1990

Nerve conduction velocity in patients under long term treatment with antiepileptic drugs.

Motor and sensory nerve conduction velocity (NCV) of median nerve and motor NCV of peroneal nerve were measured in 548 epileptic patients, aged 20 to 40 years, under long term treatment with antiepileptic drugs. Compared with a control collective of 70 healthy persons in the same age the epileptics showed a reduction of all NCVs. 19 percent of the epileptic collective had at least 1 diminished NCV. Negative correlations with total amount and average daily dose of antiepileptic drugs were found in both sexes for sensory NCV of median nerve and motor NCV of peroneal nerve, only in males also for motor NCV of median nerve. Only in females, duration of therapy correlated negative with sensory NCV of median and motor NCV of peroneal nerve. In patients under monotherapy the group with carbamazepine treatment showed the lowest NCV values, the difference being significant for motor NCV of median nerve in comparison to phenytoin and valproate sodium. It is concluded, that NCV generally is lowered under long term treatment with antiepileptic drugs and that phenytoin has no specific influence compared with the other drugs.

Adult↗
PubMed1989

A novel flagellar Ca2+-binding protein in trypanosomes.

A 24-kDa protein of Trypanosoma cruzi, the protozoan parasite that causes Chagas' disease, is recognized by antisera from both humans and experimental animals infected with this organism. Near its C terminus are two regions that have sequence similarity with several Ca2+-binding proteins and that conform to the "E-F hand" Ca2+-binding structure. We expressed a cDNA encoding this protein in Escherichia coli and showed that both the recombinant protein and the 24-kDa native trypanosome protein do indeed bind Ca2+. The protein's low Ca2+-binding capacity (less than 2 mol of Ca2+/mol of protein) and high Ca2+-binding affinity (apparent Kd less than 50 microM Ca2+) are consistent with binding of Ca2+ via the E-F hand structures. Immunofluorescence assays using a mouse antiserum directed against the fusion protein localized the native protein to the trypanosome's flagellum. The protein's abundance, Ca2+-binding property, and flagellar localization suggest that it participates in molecular processes associated with the high motility of the parasite.

Amino Acid Sequence↗
PubMed1989

The identification of sarcoplasmic reticulum terminal cisternae proteins in platelets.

Two new proteins with apparent molecular masses of 53 kDa and 190 kDa have been identified in both sarcoplasmic reticulum and human blood platelets using a monoclonal antibody, FII1b5. The sarcoplasmic reticulum FII1b5 antigens were present in the terminal cisternae fraction, but were absent from light sarcoplasmic reticulum. The platelet and skeletal muscle proteins were not sensitive to digestion with endoglycosidase H under conditions that removed carbohydrate from the 53 kDa glycoprotein in sarcoplasmic reticulum or GPIIIa in platelet microsomes and did not bind 45Ca in a nitrocellulose overlay calcium-binding assay. These results distinguished the FII1b5 antigens from the 53 kDa glycoprotein and calsequestrin of sarcoplasmic reticulum. The 190 kDa platelet and sarcoplasmic reticulum proteins were extracted from membranes with high concentrations of NaCl, indicating that the high molecular mass FII1b5 antigens are peripherally associated with the bilayers. In contrast, the platelet and muscle 53 kDa proteins remained membrane-bound in the presence of high salt concentrations, suggesting that they are integral proteins.

Acetylglucosaminidase↗
PubMed1989

Plant cells contain calsequestrin.

Calsequestrin is a high capacity low affinity Ca2+-binding protein thought to be essential for the function of the intracellular rapid releasable Ca2+ pool of a variety of animal cells. Here we show that two types of plant tissues, cultured Streptanthus tortuosus cells and spinach leaves, contain a form of calsequestrin. In subcellular fractions of S. tortuosus cells, Stains-all staining reveals a metachromatically blue-staining 56,000-Da protein enriched in the microsomal fraction. This protein shares several biochemical characteristics with animal calsequestrin: 1) it changes its apparent molecular weight with the pH; 2) it is able to bind 45Ca2+ on nitrocellulose transfers; and 3) it is recognized by antibodies against canine cardiac calsequestrin. Calsequestrin was also identified in spinach leaves using a direct extraction procedure that was developed for muscle calsequestrin. Thus, our results demonstrate that plant cells contain calsequestrin within a subcellular membrane fraction. These results also suggest that calsequestrin is an ubiquitous protein rather than being limited only to animal cells.

Animals↗
PubMed1989

Effect of cyclic adenosine monophosphate elevations on functional responses of polymorphonuclear leukocytes from patients with cystic fibrosis.

Recently, it has been suggested that the primary metabolic defect of cystic fibrosis (CF) is in the metabolic steps between an elevation of cyclic adenosine monophosphate (cAMP) and the opening of the Cl- ion channel in airway epithelial cells. Results from other studies have indicated that the primary defect may also be present in polymorphonuclear leukocytes (PMNL). In PMNL, cAMP is a potent inhibitor of cell function. We therefore used three compounds (epinephrine, theophylline, and forskolin) known to elevate cAMP in PMNL by three different mechanisms, to study the effect of an elevation of cAMP on various cell functions, such as superoxide production, membrane depolarization, and degranulation of CF patient PMNL and PMNL from healthy individuals. The baseline rates of superoxide production, degranulation, and membrane depolarization were identical for CF and control PMNL. After exposure to epinephrine as well as theophylline plus forskolin, the cell function of CF PMNL was inhibited to the same extent as that of control PMNL. Our results argue against an abnormal response of PMNL from patients with CF to an elevation of cAMP.

Adolescent↗
PubMed1989

Calciosome, a sarcoplasmic reticulum-like organelle involved in intracellular Ca2+-handling by non-muscle cells: studies in human neutrophils and HL-60 cells.

Calciosomes are intracellular organelles in HL-60 cells, neutrophils and various other cell types, characterized by their content of a Ca2+-binding protein that is biochemically and immunologically similar to calsequestrin (CS) from muscle cells. In subcellular fractionation studies the CS-like protein copurifies with functional markers of the inositol 1,4,5-trisphosphate (IP3) releasable Ca2+-store. These markers (ATP-dependent Ca2+-uptake and IP3-induced Ca2+-release) show a subcellular distribution which is clearly distinct from the endoplasmic reticulum and other organelles. In morphological studies, antibodies against rabbit skeletal muscle CS protein specifically stained hitherto unrecognized vesicles with a diameter between 50 and 250 nm. Thus both, biochemical and morphological studies indicate that the calsequestrin containing intracellular Ca2+-store, now referred to as the calciosome, is distinct from other known organelles such as endoplasmic reticulum. Calciosomes are likely to play an important role in intracellular Ca2+-homeostasis. They are possibly the intracellular target of inositol 1,4,5-trisphosphate and thus the source of Ca2+ that is redistributed into the cytosol following surface receptor activation in non-muscle cells.

Biological Transport, Active↗
PubMed1989

[Isolated abducens paralysis--a retrospective study of 165 patients].

In this retrospective study the case reports of 165 patients suffering from an abducens nerve palsy as the main presenting symptom were evaluated. The sixth nerve palsy was more frequent on the left (52%) than on the right hand side (38%), in 10% there was bilateral involvement. In 49 cases a vascular origin was suspected (29.7%), with diabetes mellitus as the most important risk factor (n = 35). Abducens palsies in inflammatory diseases (n = 32, 19.4%) were seen most often in multiple sclerosis (n = 11), viral meningoencephalitis (n = 5) and accompanying systemic viral infections (n = 5). Postvaccinal paresis was seldom (n = 1). Tumours (n = 18, 10.9%) causing sixth nerve paresis were metastases to the brain (n = 7), meningiomas (n = 3) and glioblastomas (n = 2). Nasopharyngeal carcinomas lead in 4 cases to an involvement of the abducens. Aneurysms causing sixth nerve palsy (n = 7, 4.2%) most frequent being located at the intracavernous region of the internal carotid artery (n = 4). In traumatic abducens paresis (n = 5, 3.1%) pathological findings of neuroradiological examinations are rare. In 48 patients (29.1%) diagnosis remained unclear, especially in young adults between the 20th and 40th year of age. Prognosis of abducens paresis is good in lesions of vascular and unknown origin; in these cases non-steroidal antiphlogistics are of benefit.

Abducens Nerve↗
PubMed1989

Antibodies against the Calcium-Binding Protein: Calsequestrin from Streptanthus tortuosus (Brassicaceae).

Plant microsomes contain a protein clearly related to a calcium-binding protein, calsequestrin, originally found in the sarcoplasmic reticulum of muscle cells, responsible for the rapid release and uptake of Ca(2+) within the cells. The location and role of calsequestrin in plant cells is unknown. To generate monoclonal antibodies specific to plant calsequestrin, mice were immunized with a microsomal fraction from cultured cells of Streptanthus tortuosus (Brassicaceae). Two clones cross-reacted with one protein band with a molecular weight equal to that of calsequestrin (57 kilodaltons) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting. This band is able to bind (45)Ca(2+) and can be recognized by a polyclonal antibody against the canine cardiac muscle calsequestrin. Rabbit skeletal muscle calsequestrin cross-reacted with the plant monoclonal antibodies. The plant monoclonal antibodies generated here are specific to calsequestrin protein.

Journal Article↗
PubMed1988

Inositol trisphosphate isomers, but not inositol 1,3,4,5-tetrakisphosphate, induce calcium influx in Xenopus laevis oocytes.

To investigate the mechanisms by which inositol phosphates regulate cytosolic free Ca2+ concentration ([Ca2+]c), we injected Xenopus oocytes with inositol phosphates and measured Ca2+-activated Cl- currents as an assay of [Ca2+]c. Inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) injection (0.1-10.0 pmol) induced an initial transient Cl- current (I1) followed by a second more prolonged Cl- current (I2). Both currents were Ca2+-dependent, but the source of Ca2+ was different. Release of intracellular Ca2+ stores produced I1, whereas influx of extracellular Ca2+ produced I2; Ca2+-free bathing media and inorganic calcium channel blockers (Mn2+, Co2+) did not alter I1 but completely and reversibly inhibited I2. Injection of the Ins(1,4,5)P3 metabolite, inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4) (0.2-10.0 pmol) generated a Ca2+-dependent Cl- current with superimposed current oscillations that resulted from release of intracellular Ca2+, not Ca2+ influx. Injection of the Ins(1,3,4,5)P4 metabolite, inositol 1,3,4-trisphosphate (10.0 pmol), or the synthetic inositol trisphosphate isomer, inositol 2,4,5-trisphosphate (1.0-10.0 pmol), mimicked the effect of Ins(1,4,5)P3, stimulating an I1 resulting from release of intracellular Ca2+ and an I2 resulting from influx of extracellular Ca2+. The results indicate that several inositol trisphosphate isomers stimulate both release of intracellular Ca2+ and influx of extracellular Ca2+. Ins(1,3,4,5)P4 also stimulated release of intracellular Ca2+, but it was neither sufficient nor required for Ca2+ influx.

Animals↗
PubMed1988

[Polyneuropathy following treatment of chronic hepatitis B with vidarabine].

Two patients with chronic hepatitis B received adenine arabinoside, at a dosage of 1000 mg/d for 8 weeks and 700 mg/d for 12 weeks, respectively. At the end of the treatment period both patients had developed severe sensory irritability in the distal parts of the legs: perception of all sensory modalities was impaired. The disorder persisted over the following three years, although in a milder form. Shortly after the onset of the symptoms sensory nerve conduction velocity in both lower legs was not definitely impaired. But six months later it was clearly reduced to below 40 m/sec in the sural nerve, a finding which has persisted a year later. Three years after the first examination both patients are slightly improved, but conduction velocity is not yet normal. The objectively demonstrated long course and the considerable subjective complaints associated with the polyneuropathy argue for a very therapeutic use of adenine arabinoside.

Adult↗
PubMed1988

"Calciosome," a cytoplasmic organelle: the inositol 1,4,5-trisphosphate-sensitive Ca2+ store of nonmuscle cells?

Calsequestrin (CS) is the protein responsible for the high-capacity, moderate affinity binding of Ca2+ within the terminal cisternae of the sarcoplasmic reticulum, believed up to now to be specific for striated muscle. The cells of two nonmuscle lines (HL-60 and PC12) and of two rat tissues (liver and pancreas) are shown here to express a protein that resembles CS in many respects (apparent mass and pH-dependent migration in NaDodSO4/PAGE; blue staining with StainsAll dye; Ca2+ binding ability) and is specifically recognized by affinity-purified antibodies against skeletal muscle CS. In these cells, the CS-like protein is shown by immunofluorescence and immunogold procedures to be localized within peculiar, heretofore unrecognized structures distributed throughout the cytoplasm. These structures appear to be discrete organelles, which we propose to be named "calciosomes." By cell fractionation (Percoll gradient and free-flow electrophoresis), the CS-like protein of HL-60 cells is shown to copurify with the markers of the inositol 1,4,5-trisphosphate (Ins-P3)-sensitive Ca2+ store, whereas the markers of other organelles (endoplasmic reticulum, Golgi complex, mitochondria, endosomes) and of the plasma membrane do not. Calciosome might thus be the intracellular target of Ins-P3--i.e., the source of the Ca2+ redistributed to the cytosol following receptor-triggered generation of the messenger.

Animals↗
PubMed1988

The Ins(1,4,5)P3-sensitive Ca2+ store of non-muscle cells: endoplasmic reticulum or calciosomes?

The binding of a number of extracellular ligands (hormones, growth factors, neurotransmitters etc.) to their plasma membrane receptors causes hydrolysis of phosphatidylinositol bisphosphate to initiate the formation of two second messengers, inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] and diacylglycerol, DAG. DAG has been shown to activate protein kinase C, whereas Ins(1,4,5)P3 induces the release of Ca2+ from an intracellular pool. This rapidly mobilizable, Ins(1,4,5)P3-sensitive Ca2+ store has until now been identified as the endoplasmic reticulum, ER. We demonstrate that this is untenable and provide evidence for the existence of an unrecognized organelle, the 'calciosome'. This conclusion is based on the following experimental evidence. (1) There is no correlation between the abundance of ER and the amount Ins(1,4,5)P3-sensitive Ca2+ release. (2) There is no correlation between ER markers and those for the Ca2+ store [Ins(1,4,5)P3 binding and sensitivity, Ca2+ uptake]. (3) A protein similar to striated muscle calsequestrin, CS, has been identified in microsomal fractions from a number of tissues; it copurifies with markers of the Ca2+ store, but not with those of ER. (4) Subcellular localization of the CS-like protein by electron microscopy reveals that in all cells so far analysed this protein is localized in small, membrane-enclosed structures, calciosomes, which are also stained by an anti-Ca2+-ATPase antibody. Calciosomes appear to be morphologically distinct from any other known cell organelle. (5) Although they stain different portions of the calciosomes (membrane and lumen, respectively), anti-Ca2+-ATPase and anti-CS antibodies do not recognize any antigen in ER cysternae; antibodies directed against known components of ER do not bind to calciosomes.

Animals↗
PubMed1988

Immunocytological identification of the microsomal calcium store of nonmuscle cells.

The biochemical and functional similarities between skeletal muscle sarcoplasmic reticulum and the microsomal Ca2+ store of nonmuscle cells are discussed. It is shown that antibodies raised against two characteristic proteins of sarcoplasmic reticulum, Ca2+ ATPase and calsequestrin, recognize similar proteins in nonmuscle cells. The subcellular distribution of these two antigens was studied at the subcellular levels in ultrathin cryosections. In a variety of cell types these two proteins were found to be localized in small membrane enclosed vesicles, apparently distinct from other known organelles. We propose that these newly recognized structures (calciosomes) represent the functional equivalent of sarcoplasmic reticulum in nonmuscle cells.

Animals↗