Interactive configuration through force analysis of GM1 pentasaccharide-Vibrio cholera toxin interaction

Understanding of the molecular relationships in carbohydrate-protein interactions provides useful information on biological processes in living organisms and is also helpful for development of potent biomedical agents. Herein, the interaction unbinding force between GM1 pentasaccharide and Vibrio cholera toxin (ctx) proteins was measured using atomic force microscopy (AFM), which enabled us to determine the interaction of ctx holotoxin (ctxAB) with GM1 and the interactive formation. First, the interaction force measured between A and B subunits (ctxA-ctxB) was 184.2 ± 4.5 pN, and the unbinding forces were evaluated to confirm the role of ctxA in ctxAB complex formation and were determined to be 443.7 ± 7.5 and 535.7 ± 25.9 pN for GM1-ctxB and GM1-ctxAB complexes, respectively. The force difference of ～90 pN between GM1-ctxB and GM1-ctxAB might be due to the formation of the cholera toxin complex. Importantly, from the analogue analyses, we understand how structural and binding positional differences in complex carbohydrates affect the interaction with protein and surmise that the GM1-ctxAB complex makes a "two-finger grip" formation through the conformational change of a flexible carbohydrate. In conclusion, using AFM force analysis, we successfully quantified and characterized the interactive configuration of carbohydrate-protein molecules.     

JSCP Technical Committee on Laboratory Informatics; its 10th anniversary and future perspective

BACKGROUND: Recent investigation into the push-pull effect (PPE), the reduction of +Gz tolerance when preceded by less than +1 Gz, has focused on centrifuge studies to demonstrate the presence of adverse cardiovascular responses. Maneuvers found to cause the Push-Pull Effect (PPEM) have not been studied previously in U.S. Air Force (USAF) fighter aircraft. The frequency of and extent to which PPEMs are performed in fighter aircraft are unknown. METHODS: Head-up display (HUD) videotapes from F-15 and F-16 air combat training missions were reviewed for the presence of PPEMs. The frequency of engagements containing PPEMs and the magnitude of the Gz profiles were noted. RESULTS: PPEMs were found in 11 to 67%, of engagements reviewed, depending on the nature of the training mission, with an overall average of 32%. The PPEMs that were observed contained segments of less than +1 Gz, ranging on average from 0.0 to 0.5 Gz for an average of 3.5 to 5 s duration. CONCLUSIONS: PPEMs are present in air combat training missions performed by today's USAF fighter aircraft and represent an operationally significant source of risk for accidents. These findings support continued research into the physiologic response to PPE and the development of countermeasures.     

Photo response analysis in CCD image sensors with a VOD structure

Photo response in CCD image sensors with Vertical-Overflow-Drain (VOD) was analyzed in an attempt to discover a way to lessen the photo response rise that accompanies increasing incident light intensity in the saturation region. A photo response analysis based on transistor I-V characteristics revealed that the extent of rise in the saturation region is uniquely determined by the non-ideality factor and temperature. Calculation of the non-ideality factor and its dependence on P-well impurity concentration and layer thickness further revealed that fabrication of P-wells with lower impurity concentrations and thicker layers would be effective in suppressing photo response rise     

Identification of pentosidine as a native structure for advanced glycation end products in beta-2-microglobulin-containing amyloid fibrils in patients with dialysis-related amyloidosis

beta-2-Microglobulin (beta-2m) is a major constituent of amyloid fibrils in patients with dialysis-related amyloidosis (DRA). Recently, we found that the pigmented and fluorescent adducts formed nonenzymatically between sugar and protein, known as advanced glycation end products (AGEs), were present in beta-2m-containing amyloid fibrils, suggesting the possible involvement of AGE-modified beta-2m in bone and joint destruction in DRA. As an extension of our search for the native structure of AGEs in beta-2m of patients with DRA, the present study focused on pentosidine, a fluorescent cross-linked glycoxidation product. Determination by both HPLC assay and competitive ELISA demonstrated a significant amount of pentosidine in amyloid-fibril beta-2m from long-term hemodialysis patients with DRA, and the acidic isoform of beta-2m in the serum and urine of hemodialysis patients. A further immunohistochemical study revealed the positive immunostaining for pentosidine and immunoreactive AGEs and beta-2m in macrophage-infiltrated amyloid deposits of long-term hemodialysis patients with DRA. These findings implicate a potential link of glycoxidation products in long-lived beta-2m-containing amyloid fibrils to the pathogenesis of DRA.     

Cloning of a cDNA encoding the human transforming growth factor-beta type II receptor: heterogeneity of the mRNA

A combined study of anterograde axonal degeneration and Golgi electron microscopic technique was designed to examine the distribution and density of axon terminals from the mediodorsal thalamic nucleus (MD) over layer III pyramidal cells in the prelimbic cortex of the rat. The reconstructive analysis of serial ultrathin sections of gold-toned apical and basal dendrites of layer III pyramidal cells showed that degenerating thalamocortical axon terminals from MD formed asymmetrical synaptic contacts predominantly with dendritic spines of the identified basal dendrites as well as apical dendrites. There was little difference in the numerical density of thalamocortical synapses from MD per unit length of both apical and basal dendrites.     

Trehalose 6-phosphate production with energy coupling fermentation by yeast cells

Protein phosphorylation/dephosphorylation on tyrosine residues are regulated by tyrosine kinases/phosphatases. The tyrosine phosphatase SH-PTP2 (PTP1D, PTP2C) interacts physically through its SH2 domain with phosphorylated epidermal growth factor receptor (EGFR). In KB cells, an oral epidermoid carcinoma, high epidermal growth factor (EGF) concentrations (10-9, 10-8 and 10-7 M) downregulate its receptor for the duration of the incubation with EGF. Thus, it was hypothesized that in KB cells, SH-PTP2 expression would also be downregulated by high EGF concentrations. This hypothesis was investigated by incubating the KB cells with increasing concentrations of EGF (0, 10-11, 10-10, 10-9, 10-8, 10-7 M) and by evaluating the expression of SH-PTP2 protein under these conditions. This study showed that EGF 10-7 and 10-8 M significantly decreased SH-PTP2 protein expression compared to controls. EGF 10-10 and 10-11 M did not change the expression of SH-PTP2 protein. We conclude that high EGF concentrations downregulate the expression of SH-PTP2 protein.     

Increased urinary excretion of 3-oxo-delta4 bile acids in Japanese patients with idiopathic neonatal cholestasis

This report examines the reliability of nighttime blood pressure dipping. Twenty-one individuals were studied twice with ambulatory blood pressure monitoring. On one occasion they were studied as outpatients, and on the other as inpatients on a clinical research ward. Blood pressure monitoring revealed the expected dip in blood pressure at nighttime. However, there was little test-retest reliability across the two settings. The test-retest correlations for the dip in blood pressure across the two settings were nonsignificant for systolic, diastolic, and mean arterial blood pressure. Caution is advised before diagnosing dipping or nondipping on the basis of one 24-h ambulatory blood pressure recording.     

Sudden death among 1,000 patients with myocardial infarction: incidence and contributory factors. KYSMI Study Group

Clinical indicators and the incidence of sudden death among 1,000 consecutive patients (816 males and 184 females) with myocardial infarction were investigated between 1983 and 1987 after coronary arteriography. Twenty-four patients died suddenly during a study period of 3.3 +/- 2.0 yrs. The yearly incidence of sudden death calculated by the Kaplan-Meier method was 0.7%, nearly half of the incidence of cardiac death (1.5%/yr). Univariate analysis demonstrated statistically significant differences in the number of cases with coronary thrombolysis in the acute phase, degree of coronary artery stenosis, the frequency and degree of congestive heart failure and angina in the acute and chronic phase, the presence of serious post-infarction arrhythmia, ejection fraction, recurrent myocardial infarction, and administration of digitalis and diuretics. between the sudden-death group and the cardiac and other patient groups. There was also a tendency to higher frequency of history of diabetes mellitus, presence of acute mitral regurgitation, nitrates and nicorandil treatment, and coronary artery bypass graft in the sudden-death group. Multivariate analysis revealed that digitalis and nitrates treatment and left anterior descending artery involvement were major contributing factors. Re-infarction, left ventricular ejection fraction, and nicorandil therapy were not significant and minor contributing factors. The incidence of sudden death increased with digitalis therapy (Odds' ratio of 9.59), and left anterior descending artery disease, and decreased with nitrates (0.34).