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Biomedical subjects

M Ichikawa

Publications and source records attributed to M Ichikawa.

At least 271 records · Page 15Linked to original sources
PubMed1990

Effects of easily chewable diet and unilateral extraction of upper molars on the masseter muscle in developing mice.

The effects of easily chewable diets and unilateral extraction of upper molars on the masseter muscle were studied in developing mice. A liquid diet requiring no mastication suppressed the development of the masseter muscles more than a fine-grained diet, and extraction of unilateral upper molars also caused inhibition of muscle development. Moreover, both unilateral extraction of upper molars and a liquid diet had an additive effect on the suppression of the postnatal development of the masseter muscle, and bilateral suppression of the development of the masseter muscle was induced following unilateral extraction of upper molars. These findings suggest that the sensory input from the sensory endings in the periodontal ligament may also play an important role in the postnatal development of the masseter muscle and that there may be some crossing pathways to convey the sensory input coming from the side of the extracted upper molars to the contralateral motor neurons via the interneuronal circuits.

Animals↗
PubMed1990

Synthesis of valproyl-2-pyrrolidinone and its evaluation as a cognitive drug with the ability to modulate acidic amino acids in the brain.

A new pyrrolidinone derivative, valproyl-2-pyrrolidinone (VP), was synthesized, followed by evaluation as a cognitive drug. VP gave rise to a significant protective effect against cerebral anoxia together with a potent prolongation of latency time for the reversal of scopolamine induced transient disruption of the memory of a passive avoidance response in rats. The quantitative experiment using HPLC demonstrated a significant reduction of hippocampal aspartate (Asp) and glutamate (Glu) following the intraperitoneal administration of VP at a dose of 300 mg/kg.

Administration, Oral↗
PubMed1990

No adverse effects of lead on renal function in lead-exposed workers.

A cross-sectional study was performed on 165 male lead-exposed workers to clarify the quantitative relationships between less severe exposure to lead and its effects on renal function in 1985. Mean and range of blood lead concentration (Pb-B) were 36.5 micrograms/dl and 6-73 micrograms/dl, respectively. Duration of lead exposure was 0.1 to 26.3 years. No lead-related changes were detected in serum creatinine concentration, beta-2 microglobulin in urine, creatinine clearance, beta-2 microglobulin clearance, and uric acid clearance. Twenty of the 165 workers had been exposed to lead for more than 10 years with mean duration of 21.0 years. Average concentrations of Pb-B in each individual during 1972 to 1984 were 26.1-66.6 micrograms/dl. Renal function indices of these 20 workers were not different from those of remaining lead-exposed workers whose lead exposure duration were 10 years or less. These results suggest that long-term less severe exposure to lead up to 70 micrograms/dl of Pb-B may not cause adverse effects on renal glomerular function and proximal tubular function.

Adult↗
PubMed1990

[Long-term follow-up of pyoderma gangrenosum (PG) associated with aortitis syndrome (AOS)].

It is known that PG is often associated with AOS. However, there have been no reports on long term follow-up of PG associated with AOS. We experienced a case of a 16 year old female who suffered from PG and AOS. The onset of both diseases occurred at the same time. On admission, many pustules and ulcers were found on the extremities. There was no finding of vasculitis in histopathological examinations. Development of skin lesions of PG coincided with the progress of AOS. But, AOS was progressive even when the patient was free of skin eruptions. It was concluded that the activity of PG was not always parallel to that of AOS.

Adolescent↗
PubMed1989

Recovery of olfactory behavior following removal of accessory olfactory bulb in adult rat.

It has been shown that male rats demonstrate a preference for the odor of the female rat. This preference has been suggested to be a function of the accessory olfactory pathway. Thus, changes in preference of the male rat for the odor of the female were examined following accessory olfactory bulb (AOB) removal. Preference decreased to about 30% of that seen in the intact rat during the 10 days following AOB removal. Thereafter, it increased gradually over one month survival time up to approximately 70% of the level demonstrated by the intact rat. The rats whose main olfactory bulb and AOB were removed did not show any recovery at any survival time. The time course of the behavioral recovery after AOB removal was compared with the time course of the recovery of synaptic density which was observed in the medial amygdaloid nucleus after AOB removal. The relationship between functional recovery and reorganization of synaptic connections is discussed.

Animals↗
PubMed1989

Cytoplasmic orientation and two-domain structure of the multidrug transporter, P-glycoprotein, demonstrated with sequence-specific antibodies.

The predicted cytoplasmic orientation and two-domain structure of the multidrug efflux pump P-glycoprotein were demonstrated with sequence-specific antibodies. We synthesized peptides corresponding to amino acid residues, Glu393-Lys408 (anti-P) and Leu1206-Thr1226 (anti-C) in P-glycoprotein from human mdr1 cDNA and used these peptides to produce polyclonal antibodies. From the primary structure of P-glycoprotein, and anti-C antibody is expected to recognize another position, Leu561-Thr581, in the duplicate structure of P-glycoprotein, but anti-P recognizes only one site. These antibodies bind to multidrug-resistant cells (KB-C2) with permeabilized plasma membrane but do not bind to nonpermeabilized KB-C2 cells or parental KB cells, supporting the predicted cytoplasmic orientation of these sequences. With immunoblotting of the membrane fractions from KB-C2 cells, a major 140-kDa polypeptide of the P-glycoprotein was detected with both anti-P and anti-C. Two minor polypeptides with molecular mass of 95 and 55 kDa were also detected. When membrane vesicles were digested mildly with trypsin, the amount of these two polypeptides increased. Anti-P detected only the 95-kDa polypeptide, and anti-C detected both 95- and 55-kDa polypeptides. Achromobacter lyticus protease I (lysyl endopeptidase) and Staphylococcus aureus V8 protease also produced two polypeptides with similar molecular weights. Absorption into lectin-agarose beads and labeling with [3H]glucosamine indicated that the 95-kDa polypeptide was glycosylated but that the 55-kDa polypeptide was not. These two polypeptides as well as P-glycoprotein were photoaffinity-labeled with a calcium channel blocker, [3H]azidopine, but most of the label was found in the 55-kDa polypeptide. The yield of labeled fragments from membrane vesicles photolabeled after digestion with trypsin was similar to that from membrane vesicles digested with trypsin after photolabeling. These data indicate 1) that the 95-kDa polypeptide is the fragment corresponding to the amino-terminal half of P-glycoprotein containing sugar chains; 2) that the 55-kDa polypeptide is the carboxyl-terminal half which was mainly labeled with [3H]azidopine; and 3) that P-glycoprotein has a relatively rigid structure with a small number of protease-sensitive sites and its global structure is not destroyed by tryptic cleavage.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1989

Biosynthesis, processing and half-life of P-glycoprotein in a human multidrug-resistant KB cell.

The biosynthesis, processing, and half-life of the drug efflux pump, P-glycoprotein, were studied in human multidrug-resistant KB (KB-C2) cells selected for resistance to colchicine. An antibody directed against a synthetic oligopeptide corresponding to the amino-acid sequence (Glu-393-Lys-408) of P-glycoprotein from human mdr1 cDNA was prepared in rabbits. With immunoblotting and immunoprecipitation, we detected a 140-170 kDa protein in KB-C2 cells but not in parental sensitive KB cells. KB-C2 cells made a 125 kDa precursor that was slowly processed (t1/2 = 45 min) to the mature form of 140-150 kDa. The processing rate of P-glycoprotein was slower than that of low-density lipoprotein receptor. We detected another 160-180 kDa smear band, which might be a completely denatured form of P-glycoprotein. With immunoblotting, a minor band of high molecular mass (greater than 500 kDa) was also detected and this form increased after the cells were treated with chemical cross-linker, 1,5-difluoro-2,4-dinitrobenzene. The half-life of P-glycoprotein was long; no significant loss of P-glycoprotein was observed within 24 h after synthesis. Cells treated with tunicamycin produced a 120 kDa form of P-glycoprotein which was no longer processed but showed stability similar to that of the mature 140-150 kDa form. Agents that reverse multidrug resistance, phorbol ester and transport substrate did not affect the stability of P-glycoprotein.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1989

Optimal preparatory procedures of cryofixation for immunocytochemistry.

To examine the optimal preparatory procedures of cryofixation for immunocytochemistry, the labeling density over the antigenic sites in cells processed by various protocols of freeze-substitution and embedding was quantitatively evaluated. Fresh tissue blocks of gerbil parotid gland were quickly frozen by a metal contact method using liquid helium and freeze-substituted with one of the following media: 4% OsO4 in acetone or 0.4% OsO4 in acetone or 0.3% glutaraldehyde in acetone. They were then embedded in either an Epon-Araldite mixture or Araldite 6005, which were polymerized at 60 degrees C and 50 degrees C, respectively. Some frozen samples substituted with aldehyde-containing acetone were embedded in Lowicryl K4M (polymerized at -30 degrees C). Immunocytochemical localization of amylase was examined by indirect immunostaining by using antigerbil parotid amylase antibody and protein A/gold complex. Thin sections of epoxyresin-embedded materials were treated with oxidizing agents before immunostaining. The central dense core of heterogeneous secretory granules in the acinar cells was heavily labeled with immunogold, regardless of substitution media and embedding resins employed. The labeling density on thin sections of all the cryofixed materials examined was about 1.5 times or more as high as in those processed by conventional chemical fixation. The highest value of the labeling density was obtained from material which was substituted with 0.3% glutaraldehyde in acetone and embedded in Araldite 6005. Substitution with osmium-containing acetone appeared not to seriously affect immunoreactivity of the antigenic sites and was advantageous because of the distinctive images of membranes. Advantages and disadvantages of the individual protocols employed are discussed.

Amylases↗
PubMed1989

Immunocytochemical localization of amylase in gerbil salivary gland acinar cells processed by rapid freezing and freeze-substitution fixation.

We examined the immunocytochemical localization of amylase in cryofixed serous acinar cells of gerbil major salivary glands by indirect immunostaining, using anti-gerbil parotid amylase antibody and protein A-gold complex. Fresh tissue blocks were quickly frozen by the metal-contact method, using liquid helium, and were freeze-substituted with either osmium-acetone solution or glutaraldehyde-containing acetone. They were then embedded in an epoxy resin mixture which was polymerized at 60 degrees C. Some tissue blocks substituted with aldehyde-acetone solution were embedded in Lowicryl K4M, polymerized at -30 degrees C. Thin sections of epoxy resin-embedded materials were treated with an oxidizing agent before immunostaining. The labeling density on the materials processed by various protocols for preparatory procedures was quantitatively compared to examine the usefulness of application of cryofixation to immunocytochemistry. The central dense core of heterogeneous secretory granules in the serous acinar cells of the parotid and sublingual glands was heavily labeled with immunogold, regardless of substitution media and embedding resins employed. The immunolabeling pattern clearly distinguished between the dense core and the surrounding matrix. Labeling density in the cryofixed materials was about 1.5 times greater than in those processed by conventional chemical fixation. Seromucous secretory granules in the submandibular gland acinar cells were only faintly labeled. The results obtained indicate that application of immunostaining to quick-frozen, substitution-fixed tissues is useful for high-resolution immunocytochemistry.

Amylases↗
PubMed1989

[Olfactory neuroblastoma with intracranial extension. Report of two cases].

Two cases of olfactory neuroblastoma with intracranial extension are described. The radiological features, including those of magnetic resonance (MR) imaging, are emphasized. On plain X-rays, the nasal cavity, ethmoid, sphenoid, and/or frontal sinuses were opacified. Erosion of the bony confines of the sinuses and orbit was seen in Case 1, but no bony destruction was observed in Case 2 despite intracranial tumor invasion via the seemingly intact cribriform plate. Angiography showed tumor staining in the ethmoid sinus, and in Case 1 tumor vessels were also found in the base of the frontal lobe. Computed tomography (CT) disclosed a large, soft, enhanced tissue mass occupying the nasal cavity and paranasal sinuses and extending into the anterior cranial fossa. In Case 1, MR images (0.5 Tesla) with a short spin echo sequence (repetition time [TR], 600 msec; echo time [TE], 26 msec) and a long spin echo sequence (TR, 2100; TE, 30, 60, 90) were obtained. T1-weighted images delineated the tumor accurately in relation to the normal architecture. T2-weighted images revealed widespread brain edema, with the tumor recognizable as a mass of low signal intensity within the high-intensity region of brain edema. The CT and MR imaging findings are by no means specific to olfactory neuroblastoma. However, both modalities, particularly MR imaging, are of special value in demonstrating the precise extent of the tumor in three dimensions.

Humans↗
PubMed1989

Comparisons of urinary creatinine, skeletal muscle mass, and indices of muscle protein catabolism in rats fed ad libitum, with restricted food intake, and deprived of food.

Urinary excretions of creatinine (CR) and 3-methylhistidine (3-MeHis), and skeletal muscle mass (SKM) were measured in rats (male, Wistar, weighing about 290 g) fed a 20% casein diet ad libitum, rats restricted to 70% of the food intake of the ad libitum group, and rats deprived of food for 20 days. At the same time, catabolic rates of muscle protein derived from 3-MeHis/CR, 3-MeHis/BW, and 3-MeHis/SKM were compared. The CR/SKM ratio in the energy-restricted group was similar to the ad libitum group, while the ratio was higher in the food-deprived group than in the other two groups. This means that CR excretion was promoted per unit of skeletal muscle mass by food deprivation. These results indicate that CR excretion can be an index for SKM under the condition of energy restriction, but not under the condition of food deprivation. The present data also suggest that it is possible to use the 3-MeHis/CR ratio instead of 3-MeHis/SKM which is the most reliable index of the three indices, under the condition of mild energy restriction. In food deprivation, however, the 3-MeHis/CR data tended to underestimate the catabolic rate of muscle protein compared with the 3-MeHis/SKM data. The 3-MeHis/BW data was similar to the 3-MeHis/SKM with all dietary conditions. The catabolic rate of muscle protein was constant or decreased very slightly under ad libitum feeding, decreased slightly in energy restriction, and increased drastically with food deprivation.

Animals↗
PubMed1989

[Study on retention of veneering materials to the facing crown made of hard-type resin. Application etching to Ni-Cr alloys].

In order to enhance adhesiveness between the resin and the metal in the facing crown made of hard-type resin, the bead application method has been widely utilized. A short-coming of this method is that the metal part of the facing must be made thicker for bead application. If, however, a retention is made beneath the surface of the metal part, the facing metal can be made thinner. The author studied the adhesiveness of metal to resin by producing pitting corrosion on the surface of four different kinds of Ni-Cr alloys, etching the surface with strong acid under various conditions, and compared the adhesiveness and failure conditions with those of the beaded specimens. The results were as follows: 1) The degree of corrosion of the surface of specimens was positively correlated with the duration of etching. However, the degree of corrosion differed depending on the kinds of etching solutions and specimen alloys. 2) In terms of adhesiveness, some of the etching groups were stronger than the beaded groups and some were weaker, depending on the kinds of alloys and etching conditions. 3) Condition of failure at the joint surface: in the beaded groups cohesive failure was the most prevalent type. In the etching groups, compound failure was the most prevalent. There was a positive correlation between adhesive strength and the amount of residual resin: the more residual resin, the greater the adhesive strength. 1) Electron microscopic observations: on the surface of specimens of the etching groups pitted roughness was observed, and the resin material was tightly attached to the metal surface. However, reciprocal diffusion of the elements from both materials was not indicated, nor was there any evidence of chemical bonding.

Acid Etching, Dental↗
PubMed1989

[Effects of cyproterone acetate on mouse submandibular gland].

It is recognized that the submandibular gland (SMG) of mice is one of the target organs for androgen, and a specific androgen-binding protein (androgen receptor) has been found in the cytosol fraction of this gland. Androgen participates in the production of histochemically and biochemically detected components of this gland through this receptor. Cyproterone acetate (CPA) is a synthetic progestogen which possesses antiandrogenic properties with some synandrogenic action. However, the action of CPA on the SMG has not been well defined. In the present study, the effects of CPA on the granular duct (GD) of the mouse SMG, which is the site of androgen action, were investigated using histometric, histochemical, and biochemical techniques. For histometric and histochemical experiments, normal adult male mice were treated with CPA (20, 40 and 80 mg/kg, S.C.) every second day for 5-30 days. In other experiments, castrated (CAS) and castrated-adrenalectomized (CA) mice were prepared, and they were given an injection of testosterone propionate (TP; 20 mg/kg, S.C.) and/or CPA (20 and 200 mg/kg, S.C.) every second day for 10 days. After the final administration, SMG weights were determined and the size of the GD in the SMG was measured by light microscopy using a micrometer. The sections of SMG were stained with methylgreen-pyronin, bromophenol blue, and p-dimethylaminobenzaldehyde in order to detect RNA (RNA staining), total protein (BPB staining), and granules (Try staining) in the GD, respectively. The intensity of each staining was measured by the method of Sato et al. For biochemical experiments, the mice with testicular feminization (Tfm), which are genetically deficient in androgen receptor, and genetically normal male (X/Y)-castrated mice were used. Both Tfm and X/Y-castrated mice were injected with CPA for histological experiments. After the administration period, the SMG's of both Tfm and X/Y-castrated mice were isolated and esteroprotease activity was determined by the method of Trautschold. The SMG of non-administered X/Y-castrated mice was homogenized in Tris-HCl buffer. And cytoplasmic extracts of SMG's from non-administered X/Y-castrated mice were prepared for detection of inhibitory effect of CPA on specific binding pattern of 3H-methyltrienolone (R1881) by the sucrose density gradient method.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗