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N Akamatsu

Publications and source records attributed to N Akamatsu.

At least 55 records · Page 3Linked to original sources
PubMed1997

Mechanical stability of the cementless acetabular component with three spikes.

We studied the stability of our cementless acetabular component (socket) with 3 spikes in 65 joints of 65 patients who were followed for over 5 years. In 1 case, there was osteolysis around the femoral component (stem) but not around the socket. The movement of the socket and the radiolucent line was observed in 11 cases of osteoarthritis with acetabular hypoplasia (a mean of 43 degrees of the sharp angle) and 3 cases with rapidly destructive coxarthrosis. We could obtain favorable stability in 50 patients, including 38 with osteoarthritis (a mean of 41 degrees of the sharp angle), 8 with aseptic necrosis, 2 with rapidly destructive coxarthrosis, and 2 with rheumatoid arthritis. Our socket is very effective in preventing osteolysis and is expected to provide more stable mechanical stability by arranging an insertion angle (35 degrees of the optimal open angle and 10 degrees of the anteversion angle) and a full bone graft in osteoarthritic patients.

Adult↗
PubMed1997

Preventive effect of whey hydrolysate formulas for mothers and infants against allergy development in infants for the first 2 years.

We studied the preventive effect against allergies in infants who and whose mothers consumed hypoallergenic formulas until 6 months after birth. Mother and infant pairs were divided into three groups, and the infants were monitored for the development of allergies for the first 2 years. In the MD group (n = 102; n = number of infants), the mothers were given a hypoallergenic formula for mothers (MOM HA), which contained hydrolyzed whey protein as the only protein source, as a substitution for cow's milk during late pregnancy and lactation. In the CD group (n = 127), the mothers were given cow's milk during the corresponding period. All infants in the MD and CD groups were exclusively breast-fed or mixed-fed with breast milk and hypoallergenic infant formula (NAN HA), which contains the same hydrolyzed protein as MOM HA. In the AF group (n = 54), the mothers consumed MOM HA and their infants were mixed-fed with breast milk and a cow's milk-based adopted infant formula during the corresponding period. In the MD group, no infants were positive to cow's milk-specific immunoglobulin E (RAST) at 4 months of age, in contrast to 6% and 3% of infants in the CD and AF groups, respectively. The infants in the MD group showed low incidence of various allergies, especially of eczema, as compared to the CD and AF groups. These results suggest that consumption of cow's milk by mothers and cow's milk-based formula feeding to infants elevate the risk of allergies in infants, and that consumption of hypoallergenic formula for pregnant and lactating women and for infants could be helpful in preventing allergy development in infants.

Dairy Products↗
PubMed1997

[A case of IAHS (infection associated hemophagocytic syndrome) successfully treated with etoposide].

This report details a case of infection associated hemophagocytic syndrome (IAHS). A 20-year-old female was admitted to our hospital with persistent high fever in July, 1994. Physical examination revealed high body temperature (40 degrees C), marked hepatosplenomegaly and no superficial lymph node swelling. Laboratory examination revealed leukopenia and abnormal liver function on admission. Serum ferritin levels were surprisingly elevated. The coagulation tests showed high FDP and D-dimer. Specific viral antibody titers were not elevated such as Epstein-Barr virus or Cytomegalovirus. Bone marrow examination revealed histiocytic hyperplasia with hemophagocytosis, and the histiocytes were well matured. We diagnosed IAHS. Corticosteroids were administered on the 3rd hospital day (methylprednisolone 1 g/day, 3 days), but persistent high fever and laboratory findings did not improve. So we tried etoposide (etoposide 200 mg/day, 5 days) therapy on the 13th hospital day. After administration of etoposide, she failed to recover from severe leukopenia and suffered from meningitis. We administered G-CSF, gamma-globulin and antibiotics for intensive supportive therapy. As the leukocyte count increased, her symptoms and laboratory data improved. There was no hemophagocytosis in her bone marrow before discharge. Recently, etoposide is said to be effective for reactive monocytic proliferation. Administration of etoposide was very effective for IAHS, although corticosteroids, were ineffective.

Adult↗
PubMed1996

Effects of high-density lipoproteins on intracellular pH and proliferation of human vascular endothelial cells.

We investigated the effects of high-density lipoprotein (HDL) on the intracellular pH ([pH]i), and on the proliferation of human vascular endothelial cells (HUVEC), as well as on their production of prostacyclin (PGI2). The [pH]i was slightly acidified when extracellular Ca2+ was chelated with EGTA. Pretreatment of HUVEC with amiloride, the Na+/H+ exchange inhibitor, caused the [pH]i to become strongly acidic. The addition of HDL produced a biphasic shift in [pH]i, with a brief initial acidification followed by a rapid alkaline shift. The initial decrease in [pH]i was abolished in the cells pretreated with EGTA, and subsequent alkalinization was inhibited. The alkalinization of [pH]i disappeared in the cells pretreated with amiloride. These results suggest that [pH]i depends mainly on Na+/H+ exchange and partially on the extracellular Ca2+ of the HUVEC either in the resting unstimulated state or during HDL stimulation. In contrast, the addition of LDL produced an acidification of [pH]i, which was increased by LDL in the Ca(2+)-free condition. In the cells pretreated with amiloride, [pH]i was not further acidified by LDL. As a result, HDL promoted the proliferation of cells, an action that was inhibited by pretreatment with EGTA. However LDL inhibited cell proliferation, an action unaffected by EGTA pretreatment. The addition of HDL also enhanced the generation of prostacyclin in endothelial cells, the enhancement of PGI2 generation resulted from an increase in the release of Ca2+ from storage sites, due not only to an increased production of inositol 1,4,5-trisphosphate (IP3), but also to the alkalinization of [pH]i. These effects may be involved in the mechanism of HDL's anti-atherosclerotic action.

Amiloride↗
PubMed1995

Involvement of alpha v beta 3 integrin in mediating fibrin gel retraction.

Platelet integrin alpha IIb beta 3 (GPIIb-IIIa) plays important roles in platelet-mediated clot retraction. However, little is known about the mechanisms of clot retraction mediated by nucleated cells. In this report, we demonstrate that another member of the beta 3 integrin family, alpha v beta 3, is involved in clot retraction mediated by nucleated cells. Retraction of fibrin clots was observed using a human melanoma cell line, C32TG, which contains no alpha IIb beta 3 complex. This retraction was inhibited by RGD-containing peptide, monoclonal anti-beta 3, and anti-alpha v beta 3 antibodies. Immunoelectron microscopic studies revealed a direct interaction between beta 3 integrin and fibrin fibers at an early stage of clot retraction. We found that another human embryonal cell line, 293, which is known to express alpha v beta 1, but no alpha v beta 3, lacks fibrin gel retractile activity. Upon transfection of beta 3 DNA into 293 cells, the beta 3 subunit formed a complex with an endogenous alpha v subunit. The beta 3-bearing transfectants were found to retract fibrin gels, which was specifically inhibited by anti-beta 3 antibody. In addition, a point mutation at Asp119 in the beta 3 ligand binding domain abolished the clot retractile activity of 293 transfectants, indicating the requirement of alpha v beta 3 ligand-binding activity. Our findings suggest that alpha v beta 3 is involved in mediating the interaction between the three-dimensional fibrin network and nucleated cells and in promoting "post-receptor occupancy" events.

Antibodies, Monoclonal↗
PubMed1995

Effects of hydroxyapatite and alumina sheaths on postoperative peritendinous adhesions in chickens.

Two experimental methods for restoring flexor tendon sheath integrity and preventing adhesions around traumatized flexor tendons utilizing artificial tendon sheaths made of either hydroxyapatite (HAp) or alumina were studied in a flexor tendon-trauma model and compared to a standard tendon sheath repair and a control. Eighty toes were divided equally into a control group, a sheath repair group, an HAp group, and an alumina group. Profundus tendons in zone II were divided and repaired after sublimis excision in all groups. In the sheath repair group, the flexor sheath was also repaired after suturing the tendon. In artificial sheath groups, sheaths made of HAp and alumina were placed over the repair sites to protect them from the surrounding tissues. In the control group, after repairing the tendon, the flexor sheath was excised and no artificial sheaths were used. Each toe was immobilized in a plaster cast for 3 weeks. After three weeks, the plaster cast was removed followed by the removal of the sheaths in the artificial sheath groups through a small incision in the skin in zone II. Active mobilization was encouraged in each group. Postoperative adhesions were examined at 3, 6, 9, and 12 week intervals by using light microscopic techniques. To further explore the effects of artificial sheaths on tendon healing, transmission electron microscopy was done for the HAp and alumina groups at 3, 6, and 12 week intervals. Results demonstrated decreased severity of postoperative adhesions in the HAp as well as in the alumina groups in comparison with the sheath repair and controls. A space resembling the fibro-osseous canal was formed around the tendon after removing the sheaths. This space remained patent until 12 weeks, 9 weeks after removing the sheaths, and a newly formed tendon sheath-like structure lined by synovial cells and with a peritenon-like structure over the tendon surface was observed. In the sheath repair and control groups, the severity of adhesions was decreased with the passage of time, to some extent due to unrestricted mobility. However, a newly formed tendon sheath or peritenon-like structure was not observed. Electron microscopic studies confirmed good healing at the suture in the HAp and alumina groups with no evidence of necrosis. These results are qualitative in nature as no statistical tests were performed. From these results we conclude that if the tendon is separated from the surrounding granulation tissue by a barrier with good biocompatibility, the tendon can heal with fewer adhesions.(ABSTRACT TRUNCATED AT 400 WORDS)

Aluminum Oxide↗
PubMed1995

Platelets with 10% of the normal amount of glycoprotein VI have an impaired response to collagen that results in a mild bleeding tendency.

Platelet glycoprotein VI (GPVI), a 62kD membrane protein, has been identified as one of the platelet receptors for collagen, since GPVI-deficient platelets exhibit abnormal responses to collagen and an abnormal bleeding tendency. We report a female patient with a mild bleeding history whose platelets expressed 10% GPVI of normal platelets. Shape change, aggregation and ATP release of the patient's platelets were completely absent in response to 1-5 micrograms/ml collagen but present normally in response to ADP and Ca2+ ionophore A23187. Adhesion of the patient's platelets to coated collagen was mildly affected (40-60% of normal platelets) in spite of only 10% expression of GPVI. Flow cytometrical studies revealed that the patient's platelets expressed normal amounts of the GPIa/IIa complex. These results suggest that platelet GPVI is less involved in adhesion to collagen than shape change and aggregation induced by collagen.

Adenosine Diphosphate↗
PubMed1995

Chondroitin sulfate immobilized onto culture substrates modulates DNA synthesis, tyrosine aminotransferase induction, and intercellular communication in primary rat hepatocytes.

Newly prepared phosphatidylethanolamine (PE) conjugates of glycosaminoglycans (GAGs) enabled us to immobilize GAGs to solid phase through hydrophobic interaction. Using these compounds, called GAG-PEs, we studied the effects of GAGs immobilized to culture plates coated with various extracellular matrix (ECM) proteins in terms of cell-substrate adhesion, DNA synthesis, tyrosine aminotransferase (TAT) induction, and intercellular communication in primary rat hepatocytes. Treatment with chondroitin sulfate (CS)-PE at 10 micrograms/ml made laminin, fibronectin, vitronectin, and collagens type I-V less adhesive as substrates for cell attachment and inhibited cell spreading on these substrates. The effect on cell attachment was lost after long incubations over 2 h. Dermatan sulfate (DS)-PE was also inhibitory, but less effective. The conjugates of heparan sulfate (HS), heparin, and hyaluronan were much less effective. DNA synthesis initiated by EGF in the culture on laminin substrates was inhibited most strongly by CS-PE, as well as by DS-PE and hyaluronan-PE, but not by either HS-PE or heparin-PE. With type I collagen substrates, GAG-PEs had similar effects but to lesser extent. TAT induction in the culture on laminin substrates but not on type I collagen substrates was significantly enhanced by CS-PE. In terms of DNA synthesis and TAT induction, the culture on laminin substrates treated with CS-PE was comparable to that at higher cell density on the non-treated laminin substrates. Intercellular communication assessed by dye coupling was maintained longer on the substrates treated with CS-PE. Taken together, our results demonstrate that CS immobilized especially onto laminin substrates inhibits the growth of hepatocytes and enhances their differentiated functions by modulating cell-ECM protein interactions.

Animals↗
PubMed1995

The interaction between nucleoproteins and thyroid response element (TRE) during regenerating rat liver.

We examined the interaction of nucleoproteins with thyroid response element (TRE) by south-western method. The proteins that bound specifically to TRE were detected at apparent molecular weight about 30,000 and 15,000 - 10,000. After digestion of nucleoproteins blotted on PVDF membrane with Endoglycosidase H, the amounts of TRE that bound to the nucleoproteins were increased. These results show that carbohydrate moieties of nucleoproteins have an important role on the interaction of the nucleoproteins with TRE. T3 stimulated the binding of TRE to nucleoproteins. The amount of T3 binding to nucleoproteins was changed during liver regeneration. These results indicate that T3 changes the interaction of the nucleoproteins with TRE, so T3 serves as a transducing signal to modulate the gene regulating activity of TRE-binding nucleoproteins. Liver regeneration may be controlled by these modification of interaction of nucleoproteins with DNA.

Animals↗
PubMed1994

Platelet glycoprotein IV (CD36) deficiency is associated with the absence (type I) or the presence (type II) of glycoprotein IV on monocytes.

Platelet membrane glycoprotein (GP) IV (also called CD36 and GPIIb) deficiency is associated with N(aka)-negative platelets. Using flow-cytometric analysis of cells stained with the monoclonal anti-GPIV antibody OKM5, we have studied the expression of GPIV on the monocytes from 16 healthy Japanese individuals whose platelets were deficient in GPIV. GPIV was absent on the surface of monocytes from 2 platelet GPIV-negative donors (type I), whereas it was present on the monocytes from the remaining 14 platelet GPIV-negative donors (type II). The fluorescent intensity of OKM5-stained type II monocytes was significantly (P < .05) lower than that of normal monocytes derived from platelet GPIV-positive donors, suggesting that the expression of GPIV on the type II monocytes is also abnormally regulated as compared with that on normal monocytes. OKM5 induced an oxidative burst in the type II monocytes as well as in the normal monocytes, but it failed to induce it in the type I monocytes. Because the 2 individuals with the type I deficiency have been healthy and exhibited no immunologic problems, GPIV appears to be not essential for the normal physiologic functions of monocytes. An anti-GPIV antibody was detected in the serum from one of the type I GPIV-deficient women, who had never received any blood transfusions but had given birth to three apparently healthy children. These results suggest that type I GPIV-deficient individuals may be at risk of developing an anti-GPIV isoantibody upon blood transfusion or pregnancy.

Antibodies↗
PubMed1994

Hepatocyte growth factor immobilized onto culture substrates through heparin and matrigel enhances DNA synthesis in primary rat hepatocytes.

Newly prepared phosphatidylethanolamine (PE) conjugates of glycosaminoglycans can be immobilized to solid phase through hydrophobic interaction. Primary rat hepatocytes were cultured on type I collagen or laminin substrates containing heparin-PE and assayed for DNA synthesis initiated by hepatocyte growth factor (HGF). Hepatocytes responded to HGF that had been added to culture media by active DNA synthesis and pronounced cell spreading, regardless of the presence of heparin-PE on the substrates. The preincubation with HGF, but not with epidermal growth factor, of the substrates containing heparin-PE significantly enhanced DNA synthesis and cell spreading in the absence of these mitogens in culture media. The enhancements were abolished by omitting heparin-PE or washing the HGF-treated substrates with 1 M NaCl, suggesting the immobilization of HGF to substrates through heparin. These phenomena were more evident with laminin substrates than with type I collagen substrates. Chondroitin sulfate-PE only partly substituted for heparin-PE, but Matrigel gave results similar to those of the substrates containing heparin-PE. Both type I collagen and laminin substrates containing heparin-PE bound higher amounts of HGF than the respective control substrates, whereas neither of the substrates containing chondroitin sulfate-PE did. However, the increase in HGF binding to the substrates was not as evident as the increase in DNA synthesis, suggesting that the latter is not simply due to the former but due to a concerted action of the immobilized HGF and heparin. Taken together, these results suggest that HGF can be trapped in extracellular matrix, probably through heparan sulfate in vivo, thereby acting as a mitogen for hepatocytes in cooperation with heparan sulfate.

Animals↗
PubMed1994

A computer-aided walking rehabilitation robot.

Even with recent techniques, a significant number of patients with multiple injuries cannot be mobilized at an early stage despite the fixation of all fractures. Conventional mobilization aids are not able to provide the prescribed weight bearing needed in fractures, especially those involving both the lower limbs. Robotics is a current technology aimed at improving the quality of medical care. To this end, Takatoshi Ide developed the mobility rehabilitation robot, the REHABOT. This apparatus facilitates rehabilitation by providing secure postural support and prescribed weight bearing during ambulation. The REHABOT has been used for early mobilization and gait training of severely disabled patients at different hospitals in Japan during the last 6 years. In most of the cases, this training has resulted in earlier improvement of ambulatory capability. In this paper we report the use of this device for early ambulation in two patients with multiple fractures involving the extremities and the spine. Early mobilization was achieved by initially reducing the weight bearing to 30% of body weight followed by a gradual increase governed by patient tolerance. The average length of training for these two patients was 18 days. The average total distance was 5.5 km and total walking duration was 4.5 h. After the completion of the training both patients were able to walk independently.

Adult↗
PubMed1993

Inhibitory effects of natriuretic peptides on vasopressin neurons mediated through cGMP and cGMP-dependent protein kinase in vitro.

The effects of natriuretic peptides on electrical activity and cellular cGMP levels were studied in neurons of the supraoptic nucleus (SON) of rat hypothalamic slice preparations. Intracellular and extracellular recordings showed that bath application of A type natriuretic peptide (ANP) at 100 nM or B type natriuretic peptide (BNP) at 100 to 300 nM decreased the firing rate and hyperpolarized the membrane potential in phasically firing (putative vasopressin) neurons. Non-phasically firing (putative oxytocin) neurons did not respond to these natriuretic peptides in firing rate or membrane potential. The membrane-permeable cGMP analogue 8-bromo cGMP at 0.5 mM and the phosphodiesterase inhibitor 3/isobutyl-1-methylxanthine (IBMX) at 50 microM mimicked the inhibitory effects of ANP and BNP. The specific inhibitor of cGMP phosphodiesterase 1-(3-chloroanilino)-4-phenylphthalazine+ ++ (MY5445) at 30 microM also decreased the firing rate of SON neurons. The cGMP-dependent protein kinase inhibitor N-(2-(methylamino)ethyl)-5-isoquinoline-sulfonamide dihydrochloride (H8) at 1 microM abolished the inhibition by natriuretic peptides. We measured cGMP and cAMP contents in discrete SON regions and compared the change of contents before and after application of ANP and BNP. The increases in cellular cGMP accumulation were 430% for ANP and 120% for BNP, although they did not cause significant change of cAMP accumulation. The results suggest that the inhibitory effects of natriuretic peptides on putative vasopressin neurons are mediated through cGMP and cGMP-dependent protein kinase.

1-Methyl-3-isobutylxanthine↗
PubMed1993

Qualificated discrimination of ovarian malignancy by diagnostic ultrasound.

Ultrasonograms of 214 ovarian masses in 184 patients were studied to discriminate ovarian malignancies from benign masses and to help in developing a new scoring system using ultrasonographic findings with weight-adjusted scores. The 76 masses that showed cystic patterns only were directly determined to be benign, having an expected success rate of 97.4%. The remaining 138 masses, of which 116 showed mixed patterns and 22 of which showed solid patterns, were analyzed by the Quantification method No. 2 of Hayashi to select the effective ultrasonic findings and to obtain a good discriminant function. Eleven findings (items) expressing 29 categories were selected, and a discriminant function composed with a weight-adjusted score for each category was obtained as the result of the analysis. Using these functions, the 86.6% of the ovarian masses with mixed or solid patterns were correctly discriminated as being malignant, borderline-malignant, or benign. According to internal checks of all ovarian masses, the success rate was 90.2%. Then 73 ovarian masses of 65 new patients were discriminated as the external check, and a success rate of 93.2% was obtained. It is concluded that this newly developed scoring system using ultrasonic findings is useful in discriminating ovarian malignancies from benign ones.

Algorithms↗
PubMed1993

Alteration of glycoproteins in nuclei during regeneration of rat liver.

Hepatocyte nuclei from partially hepatectomized and sham operated rats were isolated. Total and 0.35 M NaCl soluble proteins were prepared from the nuclei. The proteins were separated by gel electrophoresis and examined by lectin staining methods. Within the limits of sensitivity of these techniques, the following features emerged. 1) A majority of proteins visualized were common to and present in similar relative quantities in the nuclei during rat liver regeneration. 2) The nuclear glycoproteins were detected by several lectins. The fluctuations at the stages of the regeneration were evident. The complicated patterns of changes were observed. 3) The DNA binding activities of the nuclear proteins were observed by the south-western methods. The DNA binding activities of nuclear proteins were changed after enzyme digestion of sugar moieties of nuclear glycoproteins. From these of our results, it is suggested that the sugar chains of nuclear glycoproteins play important roles of DNA binding activities of the nuclear proteins.

Animals↗
PubMed1993

Thigh pain in cementless total hip replacement.

The incidence of thigh pain was investigated in 51 joints implanted with model Y or YII cementless total hip system. The 51 patients were followed for one or more years after surgery. Twenty-six out of 51 implanted with the model Y, and the other 25 with the model YII. Thigh pain appeared in 11 out of 26 patients (43%) replaced by model Y and in only 2 out of 25 (8%) replaced by model Y II. The difference in the incidence of thigh pain was attributed to the difference in the extent of the press fit of the stem, stress distribution and postoperative activity. To prevent thigh pain, a favorable press fit must be achieved during surgery, and the excessive weight-bearing must be restricted in postoperative course. In our improved stem design, stress is distributed uniformly on the interface between the bone and the stem resulting in reduction of thigh pain.

Adult↗