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Biomedical subjects

Masaru Shimizu

Publications and source records attributed to Masaru Shimizu.

12 recordsLinked to original sources
PubMed2005

Prospective study on early virologic response to treatment with interferon alpha-2b plus ribavirin in patients with chronic hepatitis C genotype 1b.

To evaluate the predictive value of early virologic response (EVR) of achieving a sustained virologic response (SVR), an open, prospective trial including 42 patients with chronic hepatitis C genotype 1b was performed with directly observed 24-week treatment with interferon alpha-2b plus ribavirin. We assessed the predictive values of EVR at days 3, 7, 14, and weeks 4, 8, and 12 of the SVR. The SVR in an intention-to-treat analysis was 19.0%. Patients who reached SVR presented a significantly faster reduction in plasma viral load. Stepwise multiple logistic regression analysis of the factors (gender, age, IFN dosage, ribavirin dosage, HCV RNA, ISDR, and loss of HCV RNA at week 4) revealed that loss of HCV RNA at week 4 was the only independent variable of treatment outcome (P=0.0039). A viral load at treatment day 3 above 100kIU/ml, at day 7 above 50kIU/ml, and at day 14 above 10kIU/ml was 100% predictive for virologic non-response in all except 1 patient. The cutoff levels for HCV RNA at days 3 and 14 of treatment were associated with an algorithm of the failure to detect HCV RNA after 12 weeks of treatment. In conclusions, a very early virologic response assessment could be useful for prediction of later outcome of combination therapy in chronic hepatitis C genotype 1b.

Journal Article↗
PubMed2004

Cooperative interaction of arginine-19 and the N-terminal signaling domain in the affinity and potency of parathyroid hormone.

Residue 19 of parathyroid hormone (PTH) plays a unique role in the interaction process with the PTH1 receptor. A Glu(19) --> Arg(19) substitution, based on the Arg(19) of the PTH-related protein (PTHrP), increases the binding affinity when incorporated into the N-terminus of PTH [i.e., PTH(1-20)] and has no effect when introduced into the C-terminus of PTH [i.e., PTH(15-31)]. To explore Arg(19) and the midregion (residues 10-15), we designed the novel PTH scaffold peptide, PG5, which has the PTH(1-9) domain linked to the PTH(15-31) segment via a pentaglycine spacer. Substitution of Glu(19) with Arg(19) in PG5 resulted in a 9-fold increase in binding affinity. Additionally, the substitution enhanced stimulated cAMP formation in cells expressing PTH1-delNt, a PTH1 receptor construct lacking most of the N-terminus, confirming that residue 19 is interacting with the juxtamembrane portion of PTH1. The binding and signaling capacities of the PG5 analogues were diminished relative to those of PTH(1-34), indicating that the residue 10-14 region of PTH provides more than just a simple linker function. To probe this further, the structural consequences of the glycine linker and its interaction with PTH1 were examined by circular dichroism, (1)H NMR, and extensive ligand/receptor molecular dynamics simulations. The structural data clearly illustrate the helix-stabilizing effect of Arg(19) substitution propagating N-terminally from position 19 to the pentaglycine linker. Overall, these studies suggest that an alpha-helix is the preferred conformation for the residue 15-20 region of PTH and that residues 10-14 are also required for full affinity and potency of the hormone.

Amino Acid Sequence↗
PubMed2004

Lifecorder: a new device for the long-term monitoring of motor activities for Parkinson's disease.

OBJECTIVE: To quantitatively evaluate motor activity, its fluctuations, and drug effects in patients with Parkinson's disease (PD), the Lifecorder, a new monitoring device, was attached to a group of patients for several weeks. This enabled the continuous recording of motor activity in ten scaled magnitudes at two-minute intervals for 6 weeks. PATIENTS AND METHODS: Thirteen patients with PD who required dopamine receptor agonist therapy were monitored with Lifecorder, and seven healthy subjects served as the control group. The data obtained with this device correlated well with the Unified Parkinson's Disease Rating Scale (UPDRS) and Hoehn-Yahr grading. The dose of cabergoline, a D2-receptor agonist, was increased every 2 weeks, until optimum improvement was achieved. RESULTS: By adding cabergoline, the mean UPDRS improved from 40.5 to 28.4, which was significant. In parallel, the mean daily walking count (WC) also increased from 2,459 to 3,315 steps (p < 0.01) and movement-related calorie consumption (MCC) increased from 56 to 74 kcal (p < 0.05). UPDRS thus correlated well with WC and MCC (p < 0.05) obtained with this device. The improvement ratio of WC and MCC of each individual patient was compared with that of UPDRS. WC, and MCC shifted in parallel with UPDRS with one exception. The daily time-dependent fluctuation of motor activity was clearly shown by the Excel-generated graphs to improve with D-agonist therapy. In contrast to enhanced daytime activities, nocturnal restfulness was also clearly documented with this device. CONCLUSION: The unique properties of Lifecorder make this device a useful adjunct to the UPDRS for the objective evaluation of Parkinsonian motor activity. The device has a significant advantage over conventional clinical scales, as daytime as well as nocturnal motor activity can be objectively evaluated over long time periods ranging from one hour to one month, and the magnitude of motor activity is quantifiable in relation to the time-course.

Aged↗
PubMed2004

[Postpartum cerebral angiopathy--a case report the vasculopathy associated with co-administration of two vasoconstrictives, methylergometrine maleate and sumatriptan].

A 25-year-old woman (gravida 1, para 0) who had no history indicating the toxemia of pregnancy developed hypertension and severe throbbing headache after the delivery of her first child by the cesarean section. Generalized tonic-clonic seizure ensued 5 days after the delivery, after which she did not fully regain her consciousness. Her head T2-weighted and FLAIR MRIs showed areas of multiple high intensities in the basal ganglia and cerebral white matter. Her cerebral MRA revealed the segmental stenosis and irregular wall of the major vessels, in particular of the right MCA trunk. Three weeks later, these abnormalities in the neuroimages disappeared and she was free of any symptoms. The history disclosed that obstetricians had used methylergometrine maleate for uterine contraction after delivery and then sumatriptan for her throbbing headache. We speculate that these vasoconstrictive agents might have induced the postpartum cerebral angiopathy. Postpartum cerebral angiopathy may be distinct from reversible posterior leukoencephalopathy in that the abnormalities are not restricted to the posterior lobes and that the vascular changes are apparent on neuroimagings. However, this entity might have a common underlying physiology, which is the abnormally elevated blood pressure that occurs in the setting of early postpartum period. Caution should be exercised when vasoconstrictives are to be used in postpartum period.

Adult↗
PubMed2004

[Regulation of bone mineralization by parathyroid hormone].

In randomized clinical trials, parathyroid hormone (PTH) showed potent anabolic effects on the lumbar spine and decreased the risk of incident vertebral fractures dramatically. Although the anabolic effect of PTH on cortical bone in the femoral neck is still unclear, it should be demonstrated in further clinical studies. Concurrent or sequential therapies of PTH and anti-resorptive agents will be one of the major issues of treatment for osteoporosis in the future.

Animals↗
PubMed2004

[Survey on the threshold for platelet transfusions].

We carried out a survey on platelet transfusions performed in nine general hospitals. We evaluated 303 adults who received a total of 24455 units over 1864 platelet transfusions. The underlying diseases were hematologic disorders with chemotherapy (59.7%), hematologic disorders without chemotherapy (15.5%), hematopoietic stem cell transplantation (18.5%), and others (2.0%). The patient platelet count before transfusion (platelet trigger value) was measured in only 77.1%. The platelet trigger value differed greatly between the hospitals, with an average of 2.2 x 10(4)/microl, a minimum of 1.3 x 10(4)/microl, and maximum of 3.2 x 10(4)/microl. Only 55.3% of the platelet transfusions carried out complied with the Platelet Transfusion Guideline published by the Ministry of Health, Labour and Welfare. The hospitals surveyed could be divided into those who gave mainly around 10 units and those who gave over 10 units. The total dose of platelets transfused was more in the hospitals that used mainly 15 or more unit-PCs than in the hospitals that used mainly 10 unit-PCs. These results indicate that platelet transfusion may be greatly reduced by complying with the 2 x 10(4)/microl of platelet transfusion threshold and by selecting less than 10 units of PC per transfusion.

Data Collection↗
PubMed2002

Residue 19 of the parathyroid hormone (PTH) modulates ligand interaction with the juxtamembrane region of the PTH-1 receptor.

Recent data suggest that the binding of parathyroid hormone (PTH)-(1-34) to the PTH-1 receptor (P1R) involves a high-affinity interaction between the C-terminal (15-34) domain of the ligand and the amino-terminal extracellular (N) domain of the receptor and a low-affinity interaction between the N-terminal (1-14) portion of PTH and the juxtamembrane (J) region of the receptor, with the latter interaction giving rise to signal transduction. We investigated whether residues C-terminal of position 14 in PTH(1-34) contribute to the J component of the interaction mechanism by comparing the capacity of PTH analogues N-terminally modified to improve J domain affinity and C-terminally truncated at position 14, 20, or 34 to stimulate cAMP formation in COS-7 cells transiently transfected with P1R-delNt, a P1R construct that lacks most of the N domain. In these cells, the potency of [M]PTH(1-34) (M = Ala(1,3,12),Gln(10),Har(11),Trp(14),Arg(19)) was 120-fold greater than that of [M]PTH(1-14) (EC(50)s = 3.0 +/- 0.8 and 360 +/- 90 nM, respectively) but was equal to that of [M]PTH(1-20) (EC(50) = 2.3 +/- 0.3 nM). Reverting the Arg(19) substitution of [M]PTH(1-20) to the native Glu reduced cAMP signaling potency on P1R-delNt by 12-fold (EC(50) of [M]PTH(1-20)-Glu(19) = 27 +/- 4 nM), and it decreased the analog's capacity to inhibit the binding of the J domain-selective radioligand, (125)I-[Aib(1,3),Nle(8),M,Tyr(21)]ratPTH(1-21), to the full-length P1R stably expressed in LLC-PK1 cells by 40-fold. The Glu(19) --> Arg modification, however, did not affect the capacity of PTH(15-31) to inhibit the binding of the N domain-selective radioligand (125)I-bPTH(3-34) to the full-length receptor. The overall data suggest that residues (15-20) of PTH, and particularly residue 19, contribute to the capacity of the N-terminal portion of the ligand to interact with the juxtamembrane region of the receptor. The NMR data presented in the accompanying manuscript suggests that this role could involve intramolecular effects on secondary structure in the N-terminal portion of the ligand.

Amino Acid Substitution↗
PubMed2002

[Marked thickening of the peripheral nerves in chronic inflammatory polyradiculoneuropathy associated with HCV infection].

We report a case of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) in a middle-aged patient with hepatitis C virus (HCV) infection. A 49-year-old man presented chronic progressive distal motor weakness and sensory disturbances. Laboratory findings indicated chronic liver dysfunction due to HCV infection, transient positive serum cryoglobulinemia and marked decreased motor and sensory conduction velocities in electrodiagnosis. Lumbar MRI showed marked hypertrophy of the bilateral lumbar radicular nerve roots. Steroid treatment, not IVIg, improved neurological manifestation of this patient, but the serum HCV-RNA level was extremely increased after this treatment. Choice of treatment for patients suffered from CIDP associated with HCV infection is still controversial. Newly discovered patients with HCV infection are increased in Japan in number according to the routine check their anti-HCV antibodies. It is important to monitor carefully the serum HCV-RNA level in CIDP patients associated with HCV infection when steroid treatment is initiated.

Hepatitis C, Chronic↗
PubMed2002

[Recurrent multiple cerebral hemorrhages complicated with polyarteritis nodosa].

In January 2001, a 72-year-old woman, who had been treated for polyarteritis nodosa, and vasculitic neuropathy, was admitted in somnolent state. She was monoparetic in her right leg, and disoriented. Neuroimaging studies revealed multiple superficial parenchymal hemorrhages in the bilateral hemispheres with dural Gd enhancement and parenchymal thickenings. No evidence of intracranial vasculitis was seen in visible arterial branches and veins by MRV and helical CTs. While in the hospital, intracerebral hemorrhage recurred three times. In April 2001, the third large intracerebral hemorrhage occurred, for which the removal of hematoma was carried out and brain biopsy was done. The specimens showed an evidence of cerebrovascular amyloidosis, but no inflammation. In view of the absence of angitis in the parenchymal and pial blood vessels, despite the presence of pachymeningitis, the cortical and bridging veins which drained into the venous sinuses, were likely involved in inflammation. Impaired venous drainage due to pachymeningitis might be a mechanism by which recurrent multiple cerebral hemorrhages have taken place in the presence of amyloid angiopathy.

Aged↗
PubMed2002

[PTH].

Injectable forms of parathyroid hormone (PTH) and its N-terminal fragments are bone anabolic agents proven by randomized clinical trials. Alternate delivery forms of parathyroid hormone are under clinical or preclinical studies, including nasal, transdermal, and pulmonary formulations of PTH (1-34). Oral forms of PTH (1-34) and its analogs or orally active calcium sensing receptor antagonist, which induces PTH secretion from parathyroid gland, are also under development. PTH will be the one of the major therapeutic agents for osteoporosis treatment.

English Abstract↗