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Biomedical subjects

T Shirota

Publications and source records attributed to T Shirota.

At least 55 records · Page 3Linked to original sources
PubMed1995

Effect of age and radiation on bone healing adjacent to hydroxyapatite placed in the tibia of rats.

This study investigated the effect of age and radiation on healing after implantation of hydroxyapatite granule in bone. Two groups of 16 male Wistar rats, aged 4 weeks and 2 years were used for this study. Hydroxyapatite particles were placed into the tibia 28 days after the delivery of 15 Gy of irradiation from a Linac source. The results of the present study suggest that an old rat was more vulnerable to the radiation than a young rat. It seemed that age might also be an important factor in the prognosis of the implanted hydroxyapatite in irradiated bone.

Age Factors↗
PubMed1995

[Major symptoms of multiple myeloma and their management--neurologic disorders].

The incidence of neurologic complications in multiple myeloma has been reported as high as 10 to 40% of the patients and neurologic symptoms are sometimes recognized as first manifestation of the disease. Neurologic lesions in multiple myeloma are classified as follows. 1. cerebral disorders (due to intracranial lesion, or renal insufficiency, hypercalcemia, anemia without intracranial lesion), 2. cranial nerve and intracranial involvement, 3. spinal cord or cauda equina compression, 4. radiculopathy (involvement of a nerve root). 5. peripheral neuropathy, Incidence, symptoms, and management of each disorder are reviewed with presenting case reports of the patients with multiple myeloma cases who showed neurologic disorders in our institution.

Adult↗
PubMed1995

[Benign monoclonal gammopathy].

Monoclonal gammopathy of undetermined significance (MGUS) denotes the presence of a monoclonal protein (M protein) in patients, without evidence of multiple myeloma, macroglobulinemia, amyloidosis or other related diseases. Differential diagnosis of MGUS from multiple myeloma is difficult in cases of the unusual type of each disease. A serum monoclonal protein concentration of less than 3 g/dl, normal polyclonal immunoglobulin, no or small amount of Bence Jones proteinuria and the infiltration of plasma cells of less than 10% in bone marrow are suggestive of MGUS. In the literature, about 25% of the MGUS have developed multiple myeloma or related diseases in a long term follow-up. This fact calls our attention to the management of MGUS.

Diagnosis, Differential↗
PubMed1995

A-band movement and junctional gap dissociation during caffeine-induced contracture of skeletal muscle fibers.

The action of caffeine on the myofibril profile of the sarcomere and the junctional gap of the intracellular membrane was studied ultrastructurally. When a high concentration of caffeine (5 mM) was applied, the movement of the A-band in sarcomeres dissected from the central portion of single muscle fibers was greater than that in sarcomeres dissected from the proximal and distal portions of the fiber. The amount of calcium released from the sarcoplasmic reticulum of the caffeine-treated muscle was greater in the terminal cisternae located on the narrow I band than in the wide I band, as determined by electron-probe analysis of ultrathin cryosections. The junctional gap was clearly expanded after caffeine treatment, resulting in an irreversible change in muscle contractility. These structural alterations may lead to the distinctive development of tension induced by caffeine. The expansion of the gap may also cause excitation-contraction uncoupling.

Animals↗
PubMed1994

Immediate insertion of two types of implants into vascularized bone grafts used for mandibular reconstruction in miniature pigs.

Reaction of bone tissue was investigated after placement of two different types of implants in vascularized iliac bone grafting. After the mandibles of six Göttingen minipigs were reconstructed with vascularized bone of the iliac crest, hydroxyapatite-coated implants and titanium screw implants were placed in the graft. The animals were killed at 14, 28, and 56 days after the implantation, and the healing processes were examined histologically. In the vascularized bone graft, new bone formed well around the implants, but some of the implant surfaces were covered with soft tissue by advancing bone resorption. The results suggest that a hydroxyapatite-coated implant as well as a titanium screw-type implant might be applied with a vascularized bone graft for jaw reconstruction. However, implants placed simultaneously with the vascularized bone graft had less osteointegration than implants placed in nongrafted control sites.

Animals↗
PubMed1994

[Validity of the values of maximal oxygen intake for women recommended in the 'Quantity of exercise for developing health' by Ministry of Health and Welfare].

The purpose of this study was to examine the value of maximal oxygen intake per kilogram body weight (VO2max/wt) recommended for women between 20 and 29 years of age by the Ministry of Public Welfare. The subjects were 199 female college students, who were not in the habit of drinking and smoking. Results obtained were as follows: After controlling the effects of age and percent body fat (%fat), VO2max/wt showed a significant correlations with %fat, high-density lipoprotein cholesterol and systolic blood pressure. The values of VO2max/wt corresponding to borderline values of these CHD risk factors ranged from 27.6 to 29.5ml/kg.min. The highest value of VO2max/wt was very close to the value recommended for women older than 60 years of age by the Ministry of Public Welfare. The subjects were then divided into 4 groups; at above and below the value of VO2max/wt (35ml/kg.min) recommended for women between 20 and 29 years of age, and at above and below the value of VO2max/wt (31ml/kg.min) recommended for women older than 60 years of age by the Ministry of Public Welfare. There were no significant differences among 4 groups in occurrence of abnormal values in CHD risk factors. The results of this study support the validity of the value of VO2max/wt (31ml/kg.min) recommended for women older than 60 years of age by the Ministry of Public Welfare. However, it seems that it is not necessary to recommend the value of VO2max/wt (35ml/kg.min) for women between 20 and 29 years of age, who were not in the habit of drinking and smoking.

Adult↗
PubMed1994

Reactions of bone tissue in old rats to three different implant materials.

This study compares the bone responses of old rats when implanted with hydroxyapatite ceramic (HAC)-coated titanium, high-density HAC, and uncoated titanium. Twelve two-year-old Wistar rats were used in this study. Cylindrical implants were placed into each tibia, and the animals were killed seven, 14, 28, or 56 days after implantation. Undecalcified sections were prepared and were then stained with toluidine blue. The healing process was examined histologically, and histomorphometric measurements were made with a computer-based image analyzer to quantify the percentage of implant-bone contact. The results indicated that the HAC-coated implants were superior to the uncoated titanium implants in relation to bone contact. In the cases where the bone-free surface of HAC coating was dissolved, macrophages were often seen on the surface of the implant. Although further longitudinal data are needed to evaluate the decrease of HAC coating, in this animal model, HAC-coated implants may be useful for osseous response in bones of poor quality.

Age Factors↗
PubMed1994

[Anterior segment of the eye and cranial nervous (II, III, VI, VII) infiltration in relapsing acute lymphoblastic leukemia (L1)].

A 42-year-old male was admitted with nasal bleeding. On admission he showed no abnormal neurological sign. A diagnosis of acute lymphoblastic leukemia (ALL) (L1) was made, and modified L-10M protocol was performed. During consolidation chemotherapy, the bone marrow was in remission but he showed left facial palsy. Four days after the onset of left facial palsy, the patient developed bilateral facial palsy followed by left oculomotor and abducens nerve palsy. At this time, bilateral ocular fundus showed papilloedema, exudate, bleeding, Roth's spot and leukemic infiltration to the anterior segment of the eye. Systemic chemotherapy with intrathecal injection of anti-leukemic drugs and whole brain irradiation was partially successful against cranial nervous system (CNS) complaints, but the patient relapsed. Seven month later hypopyon and secondary glaucoma developed and trabeculectomy was performed. The bone marrow revealed an increase of leukemic blasts. Chemotherapy consisting of various drugs was not effective, and he died of pneumonia. In this case, although intrathecal chemotherapy and whole brain irradiation were attempted, leukemia evolved CNS, retina and uvea despite the fact that the bone marrow was in complete remission, allowing various cranial nerve signs and ocular manifestations to occur.

Abducens Nerve↗
PubMed1993

Myelodysplastic syndrome associated with relapsing polychondritis: unusual transformation from refractory anemia to chronic myelomonocytic leukemia.

The authors report an unusual case of myelodysplastic syndrome (MDS) associated with relapsing polychondritis (RP), which developed at almost the same time as MDS. The initial diagnosis was MDS, refractory anemia (RA) subtype, according to the FAB classification. Symptoms of RP were apparently controlled by oral administration of prednisolone (PSL), although MDS was not. Within 1 month after the diagnosis, monocytosis and thrombocytopenia without excess of blasts became prominent and transformation from RA to chronic myelomonocytic leukemia (CMML) was recognized. Combination chemotherapy including daunorubicin (DNR) and cytosine arabinoside (ara-c) did not subdue the progressive monocytosis and thrombocytopenia. Finally, the patient died of pulmonary hemorrhage 3 months after the onset of the disease. The prognosis of MDS may be poorly influenced by association with RP.

Anemia, Refractory↗
PubMed1993

The effect of aging on the healing of hydroxylapatite implants.

The purpose of this study was to investigate the effect of aging on the healing process after insertion of a hydroxylapatite (HA) implant into bone. Three groups of eight male Wistar rats, aged 6 weeks (young group), 12 weeks (adult group), and approximately 2 years (old group) were used in this experiment. Two implants were placed into the tibia of each rat. The animals were killed 7, 14, 28, and 56 days after implantation, and 15-microns, hematoxylin-eosin-stained, undecalcified sections were prepared. The healing process was examined histologically, and histomorphometric measurements were made by a computer-based image analyzer to quantify the percentage of HA-bone contact and trabecular bone in the medullary cavity. In the young group, new trabecular bone formed actively around the HA implant and good HA-bone contact was achieved more rapidly than in the adult group. In the old group, both the quantity of newly formed trabecular bone around the implant and the extent of HA-bone contact were less than in the other groups. The results suggest that the rate and volume of new bone formation around implants decrease with increasing age.

Aging↗
PubMed1992

Expression of chondroitin sulfate as a unique type of proteoglycan on the cell membrane of multipotential and committed hemopoietic progenitor cells.

Proteoglycans are increasingly implicated as a major factor in the regulation of hemopoiesis. They are generally synthesized by stromal cells and released to the extracellular matrix. More recently the ability of hemopoietic progenitor cells to synthesize proteoglycans has come into focus. In the present study we maintained 3 cloned factor-dependent hemopoietic progenitor cells (B6 and F-mix which are multipotential and F-2 which is bipotential) in liquid culture. The cells were pulse-labeled with 35SO4 which becomes incorporated into the glycan side-chains of proteoglycans. We then studied subcellular distribution and chemical characterization of the newly synthesized proteoglycans. All 3 cell lines synthesized chondroitin sulfate as a unique type of proteoglycan as identified by gel filtration on a Sepharose CL-4B column followed by chondroitinase ABC cleavage of its glycosaminoglycan. This single type of proteoglycan was compartmentalized into intracellular, membrane-associated and extracellular pools. Its density on the membrane appeared to be a function of the differentiation state of the cell. The functional significance of membrane-associated proteoglycan in hemopoietic progenitor cells appears to be underestimated and requires further investigation.

Animals↗
PubMed1992

Alteration of renal function in hyperthyroidism: increased tubular secretion of creatinine and decreased distal tubule delivery of chloride.

In 77 untreated patients (16 males and 61 females, aged 12 to 65 years) with hyperthyroid Graves' disease, and in 107 control subjects (36 males and 71 females, aged 13 to 78 years), blood urea nitrogen (BUN), serum creatinine (Scr) levels, and BUN to Scr ratios (BUN/Scr) were determined. In 53 patients, the determinations were performed before treatment and after restoration of euthyroidism by treatment with an antithyroid drug. In addition, in seven untreated patients and seven normal subjects, renal clearances of creatinine (Ccr), urea nitrogen (Cun), inulin (Cin), and p-aminohippurate (CPAH) were also determined. The distal tubule delivery of chloride (DTD) and the distal fractional chloride reabsorption (DFCR) were also measured in these subjects: DTD = (CH2O + Ccl)/Cin x 100, and DFCR = CH20/(H20 + Ccl) x 100, where CH20 and Ccl stand for clearances of H2O and chloride, respectively. BUN was significantly elevated, while Scr was significantly depressed, in untreated patients with hyperthyroid Graves' disease. Accordingly, the BUN/Scr was markedly elevated. Restoration of euthyroidism accompanied the normalization of all these abnormalities. Ccr and Cun were significantly elevated, but Cin (glomerular filtration rate [GFR]) was slightly, but insignificantly, elevated in the patients. As a result, the ratios Ccr/Cin and Cun/Cin were significantly greater in the patients than in controls (Ccr/Cin, 1.42 v 1.00; Cun/Cin, 0.92 v 0.68). The amounts of urinary creatinine and urea nitrogen (UN) excretion were decreased and increased, respectively, and DTD was significantly depressed, but DFCR was unchanged in the patients. We conclude that BUN is elevated, Scr is depressed, and the BUN/Scr is increased in hyperthyroidism.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Abnormal molecular weight profile of urinary protein in rats with streptozotocin-induced diabetes.

A quantitative analysis of the molecular weight (MW) profile of urinary protein by SDS-PAGE was performed in streptozotocin (STZ)-injected, non-ketotic diabetic rats (DM group), diabetic rats receiving dipyridamole (DM-DIP group), normal rats (C group) and STZ-injected rats with near-normal glycemia due to insulin treatment (DM-INSULIN group). In the DM group, decrease of a small MW protein (SMWP) (MW 19.5 k) was found at 2.5 weeks, and an increase of larger MW proteins (LMWP) (MW 68 [albumin], 55 and 29 k) together with a decrease of SMWPs (MW 19.5 and 15 k) was found at 15 weeks, as compared to the C group: the MW profile of urinary protein in the DM-INSULIN and C groups was indistinguishable. At 15 weeks, creatinine clearance (Ccr) was significantly depressed and an increase in the mesangial matrix with electron dense deposits was evident in the DM group. The urinary protein abnormalities were partially corrected and the reduction of Ccr was absent in the DM-DIP group with no effect on glomerular morphology. STZ-induced diabetes in rats is accompanied by a reduction of urinary SMWP, and a subsequent increase of LMWP and depression of Ccr: dipyridamole ameliorates urinary protein abnormalities and prevents the reduction of Ccr.

Animals↗
PubMed1992

Increase of serum somatomedin C in hyperthyroid patients with pregnancy.

In thyrotoxic women with pregnancy, serum somatomedin C (SmC) concentration was markedly elevated (mean +/- SD 13.57 +/- 4.66 U/ml) compared to thyrotoxic women without pregnancy (1.24 +/- 1.09 U/ml), non-pregnant euthyroid women previously treated for hyperthyroidism (0.87 +/- 0.30 U/ml), normal subjects with pregnancy (6.08 +/- 3.36 U/ml) and pregnant euthyroid women previously treated for hyperthyroidism (5.98 +/- 1.52 U/ml). Since SmC/growth hormone ratio was significantly more in thyrotoxic pregnant women than in normal pregnant women and euthyroid pregnant women previously treated for hyperthyroidism, and since human placental lactogen (HPL), human chorionic gonadotropin (HCG) and prolactin (PRL) do not crossreact with SmC antibody, it is suggested that excess thyroid hormone during pregnancy results in excessive hepatic somatomedin C production.

Adult↗
PubMed1992

Exacerbation of latent heart failure by mild hypocalcemia after parathyroidectomy in a long-term hemodialysis patient.

A 60-year-old uremic patient treated with hemodialysis for 13 years developed acute hypotension during hemodialysis and overt heart failure subsequently in a period of relatively mild hypocalcemia after parathyroidectomy. Blood pressure during hemodialysis was maintained by continuous calcium infusion alone. Cardiomegaly was improved by normalization of serum calcium. The cardiac complication is considered to be exacerbation of the underlying myocardial dysfunction by the acute decline of serum calcium which might be a feature of the 'hungry bone' syndrome. Latent myocardial dysfunction might be exacerbated by only mild hypocalcemia after parathyroidectomy in long-term hemodialysis patients.

Heart Failure↗