Stochastic processes in nano-biomachines revealed by single molecule detection.

Proteins and their assemblies are in the size of nanometers and are exposed to thermal disturbances. Many molecular processes in these nano-biomachines are stochastic, reflecting the fact that the input energy level is comparable to that of thermal energy. These stochastic properties have been revealed by recently developed single molecule detection techniques.

Single molecule processes on the stepwise movement of ATP-driven molecular motors.

Movement is a fundamental characteristic of all living things. This biogenic function that is attributed to the molecular motors such as kinesin, dynein and myosin. Molecular motors generate forces by using chemical energy derived from the hydrolysis reaction of ATP molecules.

Stochastic properties of actomyosin motor.

The epoch-making techniques for manipulating a single myosin molecule have recently been developed, and the unitary mechanical reactions of a single actomyosin, muscle motor molecule, are directly measured. The data show that the unitary mechanical step during sliding along an actin filament of approximately 5.5 nm, but groups of two to five rapid steps in succession produce displacements of approximately 11-30 nm.

Discrete stochastic process underlying perceptual rivalry.

In perceptual rivalry such as ambiguous figure perception and binocular rivalry, the conscious percept spontaneously alternates between two stable interpretations of an unchanging stimulus. It is well known that the time intervals of the perceptual alternation follow a gamma distribution (GD), but its implication for the alternation mechanism has not been clarified. We examined quantitatively GDs fitted to alternation intervals, and found that the shape-determining parameter alpha of the GDs took natural numbers.

Impaired taste acuity in patients with diabetes mellitus on maintenance hemodialysis.

Aims: It has been reported that taste acuity for the four primary tastes, sour, sweet, salty and bitter, is impaired in hemodialysis (HD) patients. However, there have been no studies reported on taste acuity of diabetic HD patients. The present study aimed to quantify and compare the taste acuity of diabetic and non-diabetic HD patients, and further to determine if there were correlations between diminished taste acuity and certain blood serum parameters typically askew in hemodialysis patients.

Immunohistochemical and molecular genetic evidence for type IV collagen alpha5 chain abnormality in the anterior lenticonus associated with Alport syndrome.

Objective: To present evidence for a type IV collagen alpha5 chain (alpha5[IV]) abnormality in the anterior lens capsule of a patient with anterior lenticonus associated with Alport syndrome.

Methods: The anterior lens capsule obtained from a 54-year-old man with anterior lenticonus associated with Alport syndrome was examined ultrastructurally and stained immunohistochemically for the alpha chains of type IV collagen, alpha1(IV) to alpha6(IV). A search was also made for a mutation in the COL4A5 complementary DNA encoding the alpha5(IV) chain by reverse transcription-polymerase chain reaction of illegitimate transcripts.

Attentional set for external information activates the right intraparietal area.

Visual attention can be allocated to a location or an object by using two different types of information: internal information and external information. The results of recent psychological studies [Bagon and Egeth, Percept. Psychophys.

Uptake of N,N'-diacetylchitobiose [(GlcNAc)2] via the phosphotransferase system is essential for chitinase production by Serratia marcescens 2170.

The chiR gene of Serratia marcescens 2170, encoding a LysR-type transcriptional activator, was identified previously as an essential factor for expression of chitinases and a chitin-binding protein, CBP21. To identify other genes that are essential for chitinase production, transposon mutagenesis with mini-Tn5Km1 was carried out, and 25 mutants that were unable to produce chitinases and CBP21 were obtained. Analysis of the mutated gene of one of the mutants, N22, revealed the presence of a pts operon in this bacterium, and a mutation was found in ptsI in the operon.

Simultaneous optical and electrical recording of a single ion-channel.

In recent years, the single-molecule imaging technique has proven to be a valuable tool in solving many basic problems in biophysics. The technique used to measure single-molecule functions was initially developed to study electrophysiological properties of channel proteins. However, the technology to visualize single channels at work has not received as much attention.

Chemomechanical coupling of the forward and backward steps of single kinesin molecules.

The molecular motor kinesin travels processively along a microtubule in a stepwise manner. Here we have studied the chemomechanical coupling of the hydrolysis of ATP to the mechanical work of kinesin by analysing the individual stepwise movements according to the directionality of the movements. Kinesin molecules move primarily in the forward direction and only occasionally in the backward direction.

Superimposition of post-streptococcal acute glomerulonephritis on the course of IgA nephropathy: predominance of Th1 type immune response.

A 23-year-old man was admitted with macrohematuria and systemic edema appearing after an acute upper respiratory tract infection. He had been diagnosed 6 years earlier with IgA nephropathy (IgA-N). On admission, hypertension, nephrotic syndrome and hypocomplementemia were evident together with a high titer of anti-streptokinase (ASK).

Resurrection of grand unified theory baryogenesis.

A "new" scenario is proposed for baryogenesis. We show that the delayed decay of colored Higgs particles in grand unified theories may generate an excess baryon number of the empirically desired amount, if the mass of the heaviest neutrino is in the range 0.02 eV View Article and Find Full Text PDF

Effect of heparin chain length on the interaction with tissue factor pathway inhibitor (TFPI).

Tissue factor pathway inhibitor (TFPI) is a heparin-binding protein involved in the extrinsic blood coagulation system. In order to elucidate the minimal size of heparin chain required for the interaction with TFPI, we prepared a series of heparin-derived oligosaccharides with tailored chain length ranged from disaccharide to eicosasaccharide after the successive treatments of heparin, including partial N-desulphation, deaminative cleavage with nitrous acid and gel-filtration. Affinity chromatography study of each oligosaccharide fraction using TFPI as the ligand indicated that increasing the degree of polymerisation causes increased affinity, and that a remarkable change in the affinity occurs between the decamers and dodecamers.

Bone marrow CD34+ progenitor cells stimulated with stem cell factor and GM-CSF have the capacity to activate IgD- B cells through direct cellular interaction.

Recent studies have suggested the involvement of bone marrow in the pathogenesis of rheumatoid arthritis (RA), in which proliferation of monocyte-lineage cells (MLC) as well as local B cell activation in the synovium play an important role. Here, we show that bone marrow-derived MLC have the capacity to activate human peripheral blood IgD- B cells. Bone marrow CD34+ cells from RA patients that had been stimulated with stem cell factor and GM-CSF for 3-4 weeks (>90% CD14+ HLA-DR+ cells, <0.

Regulation of human B cell function by sulfasalazine and its metabolites.

Although sulfasalazine is a well-known disease-modifying antirheumatic drug (DMARD), the mechanisms of its action remain unclear. Indeed, it remains uncertain whether sulfasalazine itself or one of its metabolites is responsible for the antirheumatic effects of sulfasalazine. Since one of the characteristic features of rheumatoid arthritis (RA) is chronic stimulation of B cells, we compared the effects of sulfasalazine and its metabolites on the in vitro function of human B cells.

Prolonged liver dysfunction caused by hemosiderosis in a renal transplant recipient.

Background: Liver dysfunction is a frequent complication that arises in the period following kidney transplantations, often resulting in death. We reported a case proving hemosiderosis as a cause of prolonged liver dysfunction after cadaveric kidney transplantation.

Methods: A 47-year-old man, who had been undergoing hemodialysis, was referred to our hospital on 2 November 1999.

Spectral heterogeneity in single light-harvesting chlorosomes from green sulfur photosynthetic bacterium chlorobium tepidum.

The fluorescence emission properties of single chlorosomes from the green sulfur photosynthetic bacterium Chlorobium (Chl.) tepidum are studied for the first time, using a total internal reflection fluorescence microscope. The fluorescence peak positions of bacteriochlorophyll (BChl)-c self-aggregates in a single chlorosome of Chl.

Early effects of parathyroidectomy on erythropoietin production in secondary hyperparathyroidism.

Background: Secondary hyperparathyroidism (2-HPT) has an adverse effect on renal anemia and may cause a hyporesponsiveness to recombinant human erythropoietin (rHuEpo) in patients with chronic renal failure. The early effects of parathyroidectomy (PTx) on renal anemia, erythropoietin production, and nutritional state were examined.

Methods: Twenty-nine patients under hemodialysis therapy received a PTx for 2-HPT.

The motor domain determines the large step of myosin-V.

Class-V myosin proceeds along actin filaments with large ( approximately 36 nm) steps. Myosin-V has two heads, each of which consists of a motor domain and a long (23 nm) neck domain. In accordance with the widely accepted lever-arm model, it was suggested that myosin-V steps to successive (36 nm) target zones along the actin helical repeat by tilting its long neck (lever-arm).