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R K Ito

Publications and source records attributed to R K Ito.

15 recordsLinked to original sources
PubMed1997

Clinicopathologic correlations of soluble amyloid beta-protein precursor in cerebrospinal fluid in patients with Alzheimer disease and controls.

The authors compared concentrations of soluble beta-amyloid protein precursor (s beta PP) in cerebrospinal fluid (CSF) in 45 patients diagnosed with probable Alzheimer disease (AD) and 26 normal older control volunteers. Soluble beta-amyloid protein precursor concentrations were measured in 125 CSF samples using an enzyme-linked immunosorbent assay. All subjects had Mini-Mental State Examination (MMSE) and Clinical Dementia Rating Scale (CDRS) scores and assessment of disease duration. The s beta PP concentrations in CSF in the probable AD group (mean +/- SD = 493 +/- 268 micrograms/L) were decreased significantly compared with the age-matched control group (mean = 831 +/- 302 micrograms/L; p < 0.0001). In the probable AD group, MMSE scores correlated positively with s beta PP concentrations (correlation coefficient r = 0.53, p < 0.0001), and CDRS ratings and disease duration correlated inversely with s beta PP concentrations (r = -0.59, p < 0.0001 and r = -0.479, p = 0.0006, respectively). Although the decrease in CSF s beta PP from levels found in healthy elderly controls was significant in AD subjects, there was substantial overlap. In AD, CSF s beta PP was most reduced in patients in later stages of the disease. The s beta PP concentrations reflect disease severity, but utility in differential diagnosis has not been determined.

Aged↗
PubMed1994

Decreased levels of soluble amyloid beta-protein precursor are associated with Alzheimer's disease in concordant and discordant monozygous twin pairs.

We conducted immunochemical measurements of soluble amyloid beta-protein precursor (beta PP) in cerebrospinal fluid (CSF) from three monozygous twin pairs. Two of the twin pairs are discordant for Alzheimer's disease and one pair showed concordance for Alzheimer's disease, which was confirmed neuropathologically. All affected individuals displayed substantially lower levels of soluble beta PP in CSF compared with the unaffected individuals. There were no differences in total protein levels in CSF samples from the affected twins compared with those of the unaffected twins. These studies suggest that decreased soluble beta PP in CSF may reflect neuropathological processes in Alzheimer's disease involving beta PP.

Aged↗
PubMed1994

Synthesis and characterization of a recombinant hirudin-albumin complex.

The purpose of this investigation was to covalently bind recombinant hirudin (rHir) to albumin and compare alpha-thrombin inhibition by complexed rHir to rHir. rHir was radiolabelled with 125I and covalently bound to albumin using heterobifunctional cross-linking reagents. HPLC purification of the 125I-rHir-SMCC-albumin complex using gel filtration chromatography resulted in four elution peaks, with the main peak containing an average M(r) of 78 kDa. This peak fraction also contained 63% (+/- 1.4%) of the total protein and 49% (+/- 6.8%) of the 125I-rHir conjugated to albumin. Purification of unbound 125I-rHir from complex was confirmed by SDS gel electrophoresis and autoradiography. 125I-rHir inhibition of alpha-thrombin, measured by an assay utilizing the chromogenic tripeptide substrate H-D-Phe-Pip-Arg-pNA (S-2238), was observed to be non-competitive of linear mixed-type having a Ki of 1.61 pM and an alpha Ki of 1.09 pM. In contrast, complexed 125I-rHir was found to be a pure, non-competitive inhibitor having a Ki of 15.6 pM showing a ten-fold increase. These results demonstrate that covalently bound 125I-rHir still maintains potent alpha-thrombin affinity while losing minimal inhibitory capacity. Thus, successful modification of 125I-rHir serves as the foundation for future alternative applications for this potent inhibitor.

Amino Acid Sequence↗
PubMed1993

Measurement of vitamin C by capillary electrophoresis in biological fluids and fruit beverages using a stereoisomer as an internal standard.

Ascorbic acid (or vitamin C) is an important component of many biological systems and various physiological roles have been described for it. A rapid and simple capillary electrophoresis method for ascorbic acid measurements in biological fluids as well as in beverages was developed. A stereoisomer of ascorbic acid, isoascorbic acid, not normally found in nature, was used as the internal standard for this assay. The analysis was performed in a 30 cm x 75 microns I.D. fused-silica capillary with 100 mM tricine buffer, pH 8.8, and measured by UV absorbance at 254 nm. The method was sensitive to 1.6 micrograms/ml and linear to 480.1 micrograms/ml. Within-run R.S.D. was 3.2% (93.5 +/- 3.0 micrograms/ml, mean +/- S.D., n = 18) and run-to-run R.S.D. was 3.3% (35.6 +/- 1.2 micrograms/ml, mean +/- S.D., n = 10) and 1.9% (149.4 +/- 2.8 micrograms/ml, mean +/- S.D., n = 10). Average spiked recovery from human plasma samples was 98.0%. The technique has been demonstrated to be suitable for assay of vitamin C in biological samples and some fruit juices.

Ascorbic Acid↗
PubMed1993

The influence of growth hormone (rhGH) therapy on tooth formation in idiopathic short statured children.

The purpose of this preliminary study was to evaluate tooth formation in children with idiopathic short stature, before and during treatment with recombinant growth hormone (rhGH). Twenty-nine short-statured children ages 6 to 13 years were assigned into two treatment groups, an "experimental" group (n = 18), which received rhGH, and a "control" group (n = 11), which was observed for 1 year before commencing rhGH treatment. Clinical and radiographic records were obtained at the initial, year 1, and year 2 visits. Tooth formation and stature were assessed by calculating Z-scores, appropriate for the age and gender of each child. Delta-Z scores, which measure the change in Z-score over time, were also calculated between annual visits. Height was measured and recorded every 3 months, and Z-score statural norms for age and gender were derived from the 1977 National Center for Health Services national probability sampling. Tooth formation standards were derived from Moorrees et al. A matched control sample for tooth development was derived from untreated children. Tooth formation was initially delayed although the degree of reduction in stature exceeded the initial degree of delay in tooth formation. During this 2-year study, rhGH therapy had a significant influence on acceleration or gain in stature, but did not have a significant influence on tooth formation.

Adolescent↗
PubMed1991

A new canine model for evaluating blood prosthetic arterial graft interactions.

Various models have been proposed to examine blood-prosthetic materials interactions in terms of the effect of the prosthetic material on platelet structure and function, blood coagulation and fibrinolysis, and tissue infiltrates (cellular or acellular). In addition, these models have been used to examine the change in the graft surface over time. Particular difficulties in examining graft-materials interactions include species differences, short residence time for blood-materials interactions with commonly employed short grafts, and length of study limitations with ex vivo shunts. In this paper we report a canine, carotid-aorta subcutaneous prosthetic graft model. The specific advantages of this model are the length of the graft, which allows prolonged contact of blood with the prosthetic surface; the subcutaneous location of the graft, which allows repeated sampling of blood along the graft; and the healing characteristics of canine grafts. We selected the canine model because the healing characteristics are morphologically similar to those in humans in that endothelialization of the prosthetic surface is limited. Other models, such as the pig, are favored for use when examining blood coagulation, platelet, or fibrinolytic studies; however, these models can fully endothelialize prosthetic surfaces.

Animals↗
PubMed1991

Thrombin inhibition by covalently bound hirudin.

Hirudin is the most potent known natural inhibitor of thrombin and is presently gaining popularity as an anticoagulant since recombinant and synthesized forms have become available. We have made use of recombinant hirudin (rHir) by covalently binding it to both biomolecules and prosthetic biomaterials. Heterobifunctional crosslinking reagents were used to derivatize rHir and form covalent crosslinks between rHir and albumin producing active conjugates. Both derivatized rHir and conjugates inhibited human alpha-thrombin similarly, however, both showed a ten-fold decrease of alpha-thrombin inhibition when compared to rHir alone using the tripeptide substrate, S-2238. Immobilization of 2.75 +/- 0.45 micrograms rHir on 1.0 cm2 Dacron prosthetic graft patches resulted in inhibition of 1.88 +/- 0.03 micrograms alpha-thrombin in solution (mean +/- SD, n = 3), which is a 8:1 molar ratio, respectively. rHir ED50 inhibition of 0.1 NIH U alpha thrombin stimulated whole blood platelet aggregation was 0.12 x 10(-6) microM. The conjugate ED50 inhibition was 1.37 x 10(-6) microM showing an eleven-fold loss of activity. We conclude that there is only a ten-fold loss of inhibitory activity when rHir is covalently immobilized and that this technique has a benefit of localizing antithrombin activity to surfaces or soluble carrier molecules.

Adenosine Triphosphate↗
PubMed1991

Persistent platelet activation by passivated grafts.

Vascular grafts in canines exhibit similar healing patterns to humans in that the graft surface forms a pseudointima over time but endothelializes only near the anastomotic sites. Thus the pseudointima at the midportion of the graft may represent a nidus for persistent platelet activation. The purpose of this investigation was to examine the effect of the maturing graft surface on platelet activation. Long Dacron subcutaneous carotid to aorta grafts (50 cm x 8 mm) were placed in nine dogs. Blood samples were obtained by direct graft puncture, at the proximal and distal ends of the graft, at 1, 24, 48, 72 hours, 1, 2, 3, 4 weeks, and monthly thereafter for 8 months. Seven sham dogs had subcutaneous grafts implanted without arterial anastomoses, and blood samples were drawn from the femoral artery. Platelet counts were determined with a platelet counter. Platelet aggregation and release of adenosine triphosphate was determined with a whole blood aggregometer by use of arachidonic acid, collagen, and adenosine diphosphate as agonists. No difference was found in platelet aggregation to collagen or adenosine diphosphate stimulation across the graft, but platelets released significantly less adenosine triphosphate to collagen and adenosine diphosphate stimulation distally versus proximally. In the graft dogs a decrease in systemic platelet counts of 50% occurred from the preoperative level which persisted over 8 months (p less than 0.01). Also less response occurred to collagen and ADP stimulated platelet aggregation in the graft animals than the sham animals during the first month of study. These data suggest that significant platelet-graft interactions occur even after the graft has formed a mature pseudointima.

Adenosine Triphosphate↗
PubMed1988

Monoclonal antibody to human cross-linked fibrin.

Cross-linked Fibrin II was prepared using Kabi grade (L) fibrinogen. Fibrin plasmic digest was separated on Sepharose CL-6B. Fragments Mr 135-300 kDa were used to immunize 6-9 weeks old female BALB-c mice. A stable hybridoma secreting monoclonal antibody (MAb) TD-1 (IgG 2a, Kappa) was prepared by fusion using myeloma cells (P3-NS1/1-Ag4-1) and immunized cells. Fibrinogen and plasmin digest of fibrinogen in serial dilutions did not compete with the immunizing antigen. To prove that TD-1 binds specifically to cross-linked fibrin, immunoprecipitation with S. aureus and affinity chromatography were performed. In both experiments, we demonstrated that TD-1 binds specifically to a protein Mr greater than 200 kDa which is found in XL-fibrin and not fibrinogen. Reduced samples showed the antibody bands (heavy and light chains) and three protein bands, Mr greater than 80 kDa (gamma-gamma dimer), Mr greater than 45 kDa (beta chain of fragment D) and Mr greater than 16 kDa (alpha chain from fragment D) were present. TD-1 reacted strongly with HPLC fraction of the immunizing antigen Mr 220 kDa (probably DD/E complex). Affinity binding constants (Scatchard Plot Analysis) were determined. The highest affinity was obtained with XL-fibrin fraction Mr 220 kDa, KD = 1.39 X 10(-8) and high molecular weight XL-fibrin fragments, KD = 1.6 X 10(-7). Fragment DD had KD of 2.8 X 10(-6). These results suggest that TD-1 is specific for the DD region of human cross-linked Fibrin II.

Antibodies, Monoclonal↗
PubMed1986

Evaluation of the Sysmex CC-800. An automated eight-parameter hematology instrument.

An evaluation of the Sysmex CC-800 hematology analyzer (TOA Medical Electronics, Kobe, Japan, and distributed by American Scientific Products, Chicago, IL) was performed at University Hospital at Boston University Medical Center to assess the analytic performance and ease of use of the instrument. The Sysmex CC-800 is the first self-contained, fully automated, eight-parameter hematology analyzer. It can handle as many as 100 whole blood specimens without constant operator intervention. Stat and predilute modes are also available. The optional PDA-410 (particle distribution analyzer) was not evaluated in this study. Precision, linearity, carryover, and reproducibility of values over time in the automode were well within the manufacturer's specifications. The correlation study was performed with the existing Coulter S-Plus (Coulter Electronics, Hialeah, FL). The Sysmex CC-800 allowed us to expand the linear range without dilution for white blood cells to 160 X 10(3)/microL, hemoglobin to 26 g/dL, and platelets to 2,000 X 10(3)/microL. The samples on the automode exposed to normal laboratory atmosphere for up to 120 minutes showed no significant difference from baseline. The two instruments correlated well (r greater than 0.99). The authors concluded that the Sysmex CC-800 would be a reliable and time saving instrument in their laboratory.

Automation↗
PubMed1983

Antithrombin III and plasminogen: a comparison of two synthetic substrate-based methods.

We have evaluated and compared the DuPont aca and the KABI/CentrifiChem synthetic substrate-based methods for the quantitation of plasma plasminogen (PLG) and antithrombin III (AT III). Method precision was evaluated using normal human pooled plasma (NHP) as sample. Within-day and day-to-day PLG assays generated a CV of 2.0% and 2.9%, respectively, for the aca method. For the KABI/CentrifiChem PLG method, within-run (within-rotor) analysis produced a CV of 1.7%, and day-to-day analysis produced a CV of 5.3%. The relationship between the aca (y axis) and the KABI/CentrifiChem (x axis) methods for PLG was found to be y = 0.99X - 1.4%, r = 0.979. Within-day precision for AT III by the aca method generated a CV of 4.6%, and day-to-day analysis produced a CV of 7.0%. The KABI/CentrifiChem AT III method generated a CV of 4.2% and 4.4% for within-run and day-to-day assays, respectively. The AT III correlation demonstrated a relationship of y = 0.84X + 15.2%, r = 0.952. The AT III and PLG reference ranges as established in our laboratory for healthy adults, pregnant women, and for cord blood specimens also are presented.

Adult↗
PubMed1982

Coagulation, fibrinolysis, and kinin generation in adult cats.

Screening coagulation tests, coagulation factors, and components of fibrinolysis and kinin generation were examined in 21 healthy adult cats. Observed ranges for screening tests were: prothrombin time, 7.3 to 11.4 s; activated partial thromboplastin time, 10.6 to 14.9 s; and thrombin time, 10.7 to 18.9 s. Functional coagulation factors II, V, VII, VIII, IX, X, XI, and XII were assayed and expressed as percentage of normal. Although individual factors varied, the observed range for factors assayed was 37% to 208% of normal. Fibrinogen ranged from 50 to 165 mg/dl. Plasminogen and antithrombin III ranged from 50% to 200% and 89% to 111% of normal, respectively. Plasma kallikrein ranged from 0.3 to 3.9 mukat/L. Fibrin(ogen) degradation products and fibrin monomers were examined with variable and inconsistent results.

Animals↗
PubMedDate not supplied

Monitoring platelet interactions with prosthetic graft implants in a canine model.

This study shows that prosthetic arterial grafts stimulate platelets for as long as 1 year after implantation in a canine model. Carotid-to-distal aorta Dacron (DuPont, Wilmington, DE) grafts (0.8 x 50.0 cm) were tunneled subcutaneously over the right dorsal side, allowing for percutaneous arterial sampling. Thromboxane B2 (TxB2) levels were evaluated at the proximal anastomosis (w), 5.0 (x), 25.0 (y), and 50.0 (z) cm distal from w, and platelet counts and mean platelet volumes were monitored at sites w and z. TxB2 levels increased after blood entered the graft and progressively increased until the blood exited at the distal anastomosis. Platelet counts did not significantly change across the graft. Over time, systemic platelet counts decreased to approximately 50% of each dog's pregraft baseline levels and remained depressed over a 1 year period. Mean platelet volumes peaked 1-3 weeks after implant and remained greater than pregraft levels. Examination of the graft luminal surface showed a developed pseudointima characteristically similar to that which develops in mature human vascular grafts. These results suggest that healed vascular grafts in canines continue to stimulate platelet release of TxB2, reduce systemic platelet counts, and increase mean platelet volumes over 1 year. These data further suggest that platelets are stimulated by the graft and consumed.

Animals↗