Biomedical subjects
Publications and source records attributed to H Mizuta.
Stress fracture of the lateral tibial plateau is a rare occurrence. In this article we report a case of stress fracture of the lateral tibial plateau with a radiolucent fracture line in a 52-year-old man. To our knowledge, such a case has not yet been reported.
We present a case of bilateral osteonecrosis of the patella in a patient during steroid therapy and demonstrate the radiological, arthroscopic, and histological features. Osteonecrosis of the patella should be considered as a possible cause of knee pain in patients receiving steroid therapy.
Three cases of stress fracture of the proximal phalanx of the great toe occurring in a 12-year-old female volleyball player, a 17-year-old female long distance runner, and a 12-year-old male soccer player are reported. This condition probably develops after repeated forced dorsiflexion of the first metatarsophalangeal joint with changing steps. When athletes who repeatedly run and jump complain of pain in the first metatarsophalangeal joint, and there is no history of trauma, this condition should also be considered.
We investigated the spatiotemporal localization of collagen Type I, II, and X mRNAs in the subcutaneously grafted chick periosteum by in situ hybridization. Five days after transplantation, we noted three types of histological findings in the grated tissue. (a) Developing trabecular bone exhibited proliferation of spindle-shaped fibroblastic cells and polygonal osteoblasts with moderate signals for collagen Type I mRNA. (b) Developing cartilage contained ovoid chondrocytes with a moderate level of both collagen Type I and II mRNAs. Differentiating chondrocytes with increased collagen Type X mRNA developed during the course of endochondral ossification. (c) An atypical mass of cartilage weakly stained with alcian blue was composed of a large number of non-hypertrophic chondrocytes exhibiting high signals for collagen Type X mRNA. At Day 9, we observed the typical histological features of both membranous and endochondral ossification. However, sparsely distributed chondrocytes with high signals for collagen Type X mRNA were also demonstrated in osteoid and/or woven bone. The phenotype of chondrocytes showing rapid expression of collagen Type X gene derived from grafted periosteum seems to participate in the important role of endochondral bone formation in the early stage of fracture repair.
The effect of lengthening the tibia, by callotasis on the articular cartilage in the knee, was investigated histologically in 18 rabbits. The distraction rate was 1 mm per day. On the right tibia, the distraction frequency was in 2 steps (0.5mm/12 hours), while on the left it was in 120 steps (0.0083 mm/12 minutes). The 18 animals were divided into 3 subgroups based on length gain. Cartilage and subchondral bone samples were examined by light and fluorescent microscopy. The incidence of cartilage degeneration on the 2-step side was 2/5, 5/6, and 6/7 at 10, 20, and 30 percent length increases. On the 120-step side it was 0/5, 1/6, and 1/7 at the same length increases. The intensity of tetracycline fluorescence of the subchondral plate on the 2-step side was higher than that on the 120-step side, showing 1.7, 2.0, and 2.3-fold increases at 10, 20, and 30 percent length increases. Our study suggests that increasing the frequency of distraction in callotasis can help to prevent damage to articular cartilage in adjacent joints.
Lipoma arborescens is a rare intraarticular lesion, typically with a clear yellow aspirate. We report a case of lipoma arborescens with hemarthrosis of the knee.
The effect of enforced running on the morphological characteristics of the fibroblasts and on the distribution of the collagen fibril diameter in the anterior cruciate ligament of bipedal rats was examined by electron microscopy. Twelve bipedal rats were divided into two groups of equal numbers: (1) those without exercise, and (2) those with enforced exercise on a treadmill for four weeks. Ninety percent of the fibroblasts in the rats without exercise were ovoid-shaped with a round nucleus, whereas eighty-one percent of those in the rats with exercise were spindle-shaped with indented nucleus. There was a significant difference in the ratios of ovoid-shaped to spindle-shaped cells between the two groups (p < 0.05). There was an increased number of rough surfaced endoplasmic reticula and lysosomal vesicles in the fibroblasts of the rats with exercise. The collagen fibril diameters of the rats with exercise varied in size from 20 to 120 nm, while those of the rats without exercise were uniform in size, mostly between 50-80 nm. Mean collagen fibril diameter was 70.8 +/- 16.6 nm in the rats without exercise, and 66.6 +/- 21.9 nm in the exercised rats. This difference was significant (p < 0.05). These electron-microscopical findings indicate an increased collagen metabolism in the anterior cruciate ligament of rats with enforced running.
The gastrointestinal (GI) physiology of beagle dogs was regulated with a combined-treatment of intramuscular pentagastrin (10 micrograms/kg x 2) and intravenous atropine sulfate (0.02 mg/kg x 1). Here, the gastric acidity, the gastric emptying time and the small intestinal transit time in the regulated-dogs were respectively around pH 2, 0.7h and 4h, approximating those in healthy humans. The superiority of the regulated-dogs over the intact dogs was confirmed in comparative bioavailability studies by using two classes of commercial preparations. Both the conventional tablet and the sustained-release capsule of diclofenac sodium exhibited simple and similar average plasma concentration-time curves of free diclofenac in the intact dogs, while the latter preparation is reported to reveal a bimodal plasma curve of the drug in healthy humans. The regulated-dogs, however, permitted a bimodal average plasma pattern of the drug for the capsules due to an approximation of the GI physiology between humans and these classes of the dogs. The combined-treatment of beagle dogs with pentagastrin and atropine sulfate seems to supply a useful animal model in predicting the absorption characteristics of the sustained-release preparations and poor water-soluble drugs.
The purpose of this study was to investigate the relationship between the appearance of basal lamina components (Type IV collagen and laminin) and the development of cartilage canals. In the distal femoral epiphyses from developing rats, the distribution of basal lamina components in the cartilage canal was examined immunohistochemically. The formation of cartilage canals from the perichondrium was first observed on the fifth day after birth. By Day 8, a few cartilage canals penetrated the epiphyseal cartilage and considerably increased in size and length. By light microscopic immunohistochemistry, reticular structures stained with anti-Type IV collagen and antilaminin antibodies were observed in the cartilage canals. In the early development of cartilage canals, however, immunostaining by anti-Type IV collagen antibodies was weaker than that by antilaminin antibodies. In eight-day-old rats, the laminin-positive reticular structures were more densely colored and more widely distributed in the canal than the Type IV collagen-positive ones. Type IV collagen was found around the endothelial cells of the developing capillaries by electron microscopic immunohistochemistry. Laminin was observed in the cytoplasm of the mesenchymal fibroblastic cells and their pericellular matrix as well as in the capillary basal lamina. These immunohistochemical electron microscopic observations can explain the differences that are observed in Type IV collagen and laminin immunostaining patterns as cartilage canals develop. Laminin synthesized by the mesenchymal fibroblastic cells may promote the migration and the outgrowth of endothelial cells in the formation of cartilage canals.
The purpose of this study was to evaluate the effect of enforced exercise on the biomechanical properties of the anterior cruciate ligament (ACL) in bipedal rats. These rats were divided into two groups: (1) bipedal rats without exercise, E(-)G, and (2) bipedal rats with exercise for 4 weeks, E(+)G. Strength (the maximum load that can be sustained by specimen prior to rupture) results for E(+)G were significantly lower than those for E(-)G at the loading rates of 8.3 mm/sec and 1 x 10(3) mm/sec. Stiffness (the slope of the load-deformation curve for a specimen with a linear-deformation relationship) results for E(+)G were significantly lower than those for E(-)G at the rate of 8.3 mm/sec. A load relaxation test (a test of viscoelastic behavior characterized by a decrease of load in a specimen with time under a constant load or deformation) showed a larger load-relaxation phenomenon (a decline in load over time under a constant deformation) in E(-)G. Analyzing these results by a three-element model, we found that the viscosity was higher in E(+)G than in E(-)G. This study offers insight into the effects of exercise on the ACL of humans.
To investigate the clinical significance of membrane-associated phospholipase A2 (M-PLA2) measured by a radioimmunoassay(RIA) in rheumatoid arthritis, we examined serum M-PLA2 concentrations in 16 patients with rheumatoid arthritis. All showed elevated levels of serum M-PLA2. On the other hand, serum concentrations of C-reactive protein (CRP) and IL-6 were increased in 13 (81.3%) and 14 (87.5%) of 16 patients, respectively. The serum concentrations of M-PLA2 were significantly correlated with those of CRP. These results indicate that M-PLA2 is an acute phase reactant and a sensitive and useful marker of inflammation in rheumatoid arthritis.
Spinal epidural hematoma (SEH) is comparatively rare. In most cases, urgent surgical decompression is necessary. Several reports have described spontaneous remission of SEH. The authors present a rare case of spontaneous resolution of cervical SEH.
A tandem dimer of miscanthus streak virus (MiSV) DNA was inserted into the T-DNA of the binary plasmid vector pBIN19 and agroinoculated into several monocotyledonous plants (monocots) using Agrobacterium tumefaciens or A. rhizogenes. Disease symptoms and geminate particles were produced in maize and Panicum milaceum plants, and MiSV-specific double-stranded and single-stranded DNAs were found in these plants. The nucleotide sequence of the infectious MiSV clone, consisting of 2672 nucleotides, was determined. Four open reading frames (ORFs) for proteins of Mr greater than 10K were identified, two (V0 and V2) in the virus (+) sense and two (C1 and C2) in the complementary (-) sense, although C2 did not have an ATG start codon. Unlike other geminiviruses infecting monocots, complementary-sense ORFs did not overlap. Potential splicing donor and acceptor sites were identified in the sequence of the border region between the C terminus of ORF C1 and the N terminus of ORF C2. Amino acid sequences predicted from three (V2, C1 and C2) of these ORFs showed significant homology with the corresponding ORFs of other geminiviruses infecting monocots. A fifth ORF (V1), which showed some homology with ORF V1 of other monocot-infecting geminiviruses despite having a coding capacity for a product of Mr 8.8K, was found just upstream of ORF V2 as observed in those geminiviruses. ORF V0 showed no significant homology with ORFs present in any other geminiviruses. A mutation of V0 indicated that the C-terminal 30% of this ORF was not necessary for infection in maize, but that sequences around the mutated LspI site might have some regulatory role.
The relationship between the oral absorption and gastrointestinal transit time of nitrofurantoin was investigated in dogs by the double-marker method using acetaminophen and salicylazosulfapyridine as markers. The extent of bioavailability of nitrofurantoin gave correlations with both gastric emptying time and small intestinal transit time. The results indicate that the slower the passage from the stomach into the small intestine and/or the longer the residence time in the small intestine, the oral absorption efficiency of nitrofurantoin increases. These observations were consistent with the reported findings from in situ absorption study in rats and intestinal intubation study in humans, respectively. Moreover, it was clarified that small intestinal transit time is the most important determinant of absorption of nitrofurantoin, since the good correlation was observed between the small intestinal transit time and the extent of bioavailability. The double-marker method appears consequently to be useful tool for the determination of the gastrointestinal transit time in dogs.
The effects of triglycerides on the gastrointestinal absorption of 2-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)-1H-pyrazolo[3,4-b]pyridin-1- yl]ethyl acetate (1) were investigated in dogs. The enhancing abilities of the triglycerides on the absorption of 1 were demonstrated as in the order of trilinolein greater than triolein greater than tristearin greater than tripalmitin. Among the series of fatty acids and monoglycerides, namely, digestive products of triglycerides by pancreatic lipase, linoleic acid and monolinolein showed the most potent solubilizing activities of 1 in a solution of bile salt. The incorporation of 1 into mixed micelle formed by lipids and bile salts was presumed to play an important role in the accelerated absorption of 1 after ingestion of triglycerides. On the basis of these findings, an emulsion containing 1 was prepared with soybean oil. The emulsion exhibited a remarkable improvement of the absorption of 1 compared to a suspension of the drug in methylcellulose solution.
Effects of the amount and the composition of meals on gastric emptying and small intestinal transit times of a suspension were investigated in beagle dogs using acetaminophen and salicylazosulfapyridine as markers. Gastric emptying time was affected both by the amount and the composition of a meal; it was prolonged proportionally to the amount of a solid meal and varied among the 3 kinds of test meals of the same energy content in the following rank order: lard greater than skimmed milk greater than mashed potatoes. The inter-individual variation of small intestinal transit time in a fed state was smaller than that in a fasted state, whereas the mean transit times in both states were similar. Small intestinal transit time was not affected by the amount of the solid meal. On the other hand, it varied among the 3 kinds of test meals in the following rank order: lard greater than mashed potatoes greater than skimmed milk. It is noteworthy that small intestinal transit time in the beagle dog is approximately 2 h shorter than that in humans both in fasted and fed states.
The pharmacokinetics of a new lipophilic substituted benzamide N-[(1-butyl-2-pyrrolidinyl)methyl]-2-methyl-5-sulfamoyl-2,3- dihydrobenzofuran-7-carboxamide hydrochloride (1) and sulpiride in both plasma and brain were investigated in rats. The octanol-water partition coefficients of the base of 1(2) and sulpiride were 6.3 and 0.2, respectively. The eliminations of 2 from plasma and brain were similar to those of sulpiride. The systemic bioavailabilities of 1 and sulpiride after oral administration of 200 mg/kg were 60.9 +/- 10.9 and 18.2 +/- 6.4%, respectively. The brain concentrations of 2 were about 2-3 times higher than those of sulpiride until 4 h after oral administration of 100 mg/kg. The brain/plasma ratios of 2 were about 2 times higher than those of sulpiride. These results indicate that the penetration of 2 through the gastrointestinal membrane and/or the blood-brain barrier are higher than those of sulpiride.
Gastrointestinal absorption properties of chlorothiazide was investigated in dogs by a double-marker method using acetaminophen and salicylazosulfapyridine as the markers. The mean absorption time of acetaminophen (MATAAP) and the time for first appearance of sulfapyridine in plasma (TFASP) were used for the assessment of gastric emptying and oro-colonic transit times, respectively. Chlorothiazide absorption efficiency was increased by pretreatment with atropine sulfate. There was a good correlation between MATAAP and the extent of bioavailability of chlorothiazide, however, there was no correlation between TFASP and the extent of bioavailability of the drug. These results indicate that chlorothiazide absorption takes place primarily in a limited segment of the upper small intestine, supporting the assumption reported previously. This double-marker method seems to be a useful tool for the investigation of the relationship between drug absorption and its gastrointestinal transit.