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Biomedical subjects

K Sakamaki

Publications and source records attributed to K Sakamaki.

At least 55 records · Page 3Linked to original sources
PubMed1991

Steel-Dickie (Sld) mutation affects both maintenance and differentiation of testicular germ cells in mice.

The effects of Steel-Dickie (Sld) mutations on testicular germ cell differentiation were investigated using experimental cryptorchidism and its surgical reversal in mutant, C57BL/6-Sld/+ and wild-type C57BL/6- +/+ mice. In Sld/+ cryptorchid testes the maintenance of undifferentiated type-A spermatogonia was impaired and their numbers decreased. In contrast, the proliferative activity of type-A spermatogonia in the cryptorchid testis of mutant mice appeared normal as judged by their progression through the cell cycle. Surgical reversal of cryptorchidism resulted in regenerative differentiation of mature germ cells in +/+ testes. However, the regenerative differentiation of type-A spermatogonia which remained in Sld/+ cryptorchid testes was strongly impaired, particularly at two steps of cellular differentiation, from type-A spermatogonia to intermediate or type-B spermatogonia and at meiotic division. Furthermore, in mutant mice, no significant recovery of testicular weight was observed after surgical reversal compared with +/+ mice.

Animals↗
PubMed1991

Effect of the W mutation, for white belly spot, on testicular germ cell differentiation in mice.

The effect of the mutation for white belly spot controlled by the dominant gene W on spermatogenesis in mice was examined by experimental cryptorchidism and its surgical reversal. The course of spermatogenesis from spermatogonia to spermatid was normal in intact testes of W/+ mice. In cryptorchid testes, there was no difference in the number and activity of Type A spermatogonia between the testes of W/+ and +/+ mice, in mitotic and labelling indices. Although surgical reversal of the cryptorchid testis resulted in regenerative differentiation of germ cells in both genotypes, the recovery of cell differentiation in the W/+ testis was slower than in the +/+ testis. There were fewer germ cells, such as intermediate-Type B spermatogonia or more advanced ones, in W/+ testes. On Day 17 after surgical reversal, cell associations in W/+ testes were abnormal and the numbers of intermediate-Type B spermatogonia, spermatocytes and spermatids were approximately 70, 50 and 15%, respectively, of those in +/+ testes. These results indicate that the W gene affects spermatogenic cell differentiation in adult mice.

Animals↗
PubMed1990

Ultrasound diagnosis of lymph node metastasis in head and neck cancer.

The role of ultrasonic (US) examination in the detection of cervical lymph node metastasis from head and neck cancer has been evaluated. The subjects were 57 patients with carcinoma of the oral cavity, maxillary sinus or oropharynx who underwent radical neck dissection. The preoperative US and postoperative histopathological findings were compared in 181 lymph nodes (LNs) of 5 mm or more in diameter. LNs were evaluated by US with reference to their size, shape, boundary and internal echoes. The histologically positive rate was higher for larger LNs on US scans: 96% (44/46) of LNs of 15 mm or more were positive. On the other hand, 95% (18/19) of the flat LNs were negative. The positive rate was higher for well delineated than poorly delineated LNs, but similar among the homogeneous, heterogeneous and reflective core patterns of internal echoes. No LNs were detected by US in six of the 57 patients, of which four were true negative and the other two false negative. In the two false negative patients, histopathological examination showed a total of four LNs with two showing extensive extranodal spread of tumour and fibrosis of the surrounding tissue due to previous radiotherapy. Whether LNs are metastatic or not is difficult to determine directly by US. However, the positive rate can be enhanced by evaluation of the size, shape and boundary of the LN. US is indispensable for diagnosing cervical lymph node metastasis in patients with malignant head and neck tumours.

Head and Neck Neoplasms↗
PubMed1989

Molecular cloning and characterization of a chromosomal gene for human eosinophil peroxidase.

Using human myeloperoxidase cDNA as a probe, a chromosomal gene related to myeloperoxidase was isolated from a human gene library. Comparison of the amino acid sequence deduced from the nucleotide sequence of the cloned gene with that of human eosinophil peroxidase purified from buffy coats has indicated that the isolated gene is the chromosomal gene for human eosinophil peroxidase. Like human myeloperoxidase gene, human eosinophil peroxidase gene consists of 12 exons and 11 introns spanning about 12 kilobases. The gene can code for a protein of 715 amino acids with a calculated Mr of 81,036. The heavy chain and the light chain of eosinophil peroxidase were located on the COOH and NH2 terminus of the protein, respectively. The coding sequences of eosinophil peroxidase and myeloperoxidase show homologies of 72.4% at the nucleotide and 69.8% at the amino acid level, while little homology was found in the 5'-flanking region. Northern hybridization and S1 mapping analysis of RNA from human leukemic cells have indicated that the eosinophil peroxidase gene is expressed in the eosinophilic subline of human HL-60 cells but not in the neutrophilic subline or in parental HL-60 cells.

Amino Acid Sequence↗
PubMed1989

Identification of peanut agglutinin receptors on mouse testicular germ cells.

Peanut agglutinin receptors expressed specifically in mouse testicular germ cells have been identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and lectin blotting techniques. Two major components were estimated to have molecular weights of 86,000 and isoelectric points of 6.1 +/- 0.3 and 6.2 +/- 0.3. Minor components with molecular weights of 71,000-74,000 and isoelectric points of 6.1 +/- 0.3 were also detected. Specific expression of these receptors on testicular germ cells was confirmed using the testes of mutant mice, Sld/Sld, devoid of germ cells.

Animals↗
PubMed1987

Primary malignant melanomas of the oral mucosa.

7 patients with primary malignant melanoma of the oral mucosa treated during the past 15 years by extensive resection, and simultaneous neck dissection in 3 of them, are reported. 4 patients died. However, most of the patients stayed alive relatively long postoperatively.

Adult↗
PubMed1987

Identification of the specific proteins associated with differentiation of spermatogonia in mice by two-dimensional gel electrophoresis.

Protein synthesis in testicular germ cells was studied during the differentiation of Type A spermatogonia in testes from adult cryptorchid mice to Intermediate and Type B spermatogonia in organ culture by two-dimensional gel electrophoresis. By comparing the patterns of Type A spermatogonia with those of differentiated (Intermediate and Type B) spermatogonia, we found two newly synthesized protein spots that correlated with differentiation. The isoelectric points (pIs) and molecular weights (MWs) of these proteins were estimated to be approximately pI 5.4, MW 67,000, and pI 5.8, MW 28,000, respectively.

Animals↗
PubMed1986

Effect of duration of cryptorchidism on ability of mouse germ cells to regenerate and differentiate.

When 2-month-old mice were made cryptorchid for periods of up to 19 months, testicular weight fell between 0 and 10 days, remained steady until 7 months, fell rapidly until 12 months, and then remained low. The recovery of weight gain of the testes after surgical reversal of the cryptorchidism was related to the duration of cryptorchidism. After 8 months very little change in testicular weight or specific activity of lactate dehydrogenase X was obtained.

Animals↗
PubMed1986

Ulnar collateral ligament tears of the elbow joint.

The functions of the elbow in 13 cases of ulnar collateral ligament (U.C.L.) tears without gross intraarticular complications were retrospectively evaluated. Ten cases had been surgically repaired, and the remaining three cases were treated conservatively. Follow-up examinations were performed on all of the patients. There was a significant difference in valgus instability between operatively treated patients and conservatively treated patients (operatively treated patients averaged 5.1 degrees, while conservatively treated patients averaged 8 degrees). Two cases of conservatively treated patients complained of elbow joint pain while playing sports or working. Conversely, one of the operatively treated patients complained of numbness in the fifth finger. However, the remaining cases had no symptoms, even while playing sports or working. Valgus instability of the elbow joint results in little inconvenience in daily life, but it is disabling in patients performing heavy labor or vigorous sports.

Adolescent↗
PubMed1985

Effects of steel mutation on spermatogenesis stimulated by fetuin.

The effect of the steel mutation on spermatogenesis was investigated using organ culture. Cultured cryptorchid testes from WB-+/+ mice showed an effective differentiation of type A spermatogonia in response to Pedersen type III fetuin. In contrast, the cryptorchid testes from WB-S1/+ showed neither differentiation nor division of type A spermatogonia. The findings reported here are the first demonstration of retarded response of steel mutation on a well-known agent, fetuin.

Alleles↗
PubMed1981

A new method for measurement of bone mineral deposition pattern--using dual energy radiographic densitometry method in a single exposure.

Quantitative observations of bone mineral distribution in the maxillo-mandibular bone are of great interest in the clinical field. Radiographic densitometry is the most simple method but the film density is influenced by the X-ray exposure and processing conditions and by the soft tissue layers. This fluctuation can be corrected from the image of the wedge of the reference material simultaneously projected with the object on the same film. There is no other method than the dual energy technique to correct the effect of the soft tissue layer to be applicable in the maxillo-mandibular region. Two radiograms of the object obtained by a different beam quality represent the different X-ray contrast. When the penetrated fractions of the incident X-rays through the object at different energies are obtained from the film density and the characteristic curve of the film and substituted for the first order simultaneous equation whose coefficients are the mass attenuation coefficients of the bone mineral and soft tissue to the X-rays of the respective energy, the bone mineral content is obtained as the solution of the equation in the form of the product of the mineral density and the thickness of the bone (mg/cm2). This paper shows the principle of the method and the results of the experiment which agreed closely with the data obtained by the chemical assessment.

Absorptiometry, Photon↗
PubMed1978

Measurement of integral absorbed dose by chemical dosimeter in panoramic tomography.

As an aqueous chemical dosimeter for measuring ionizing radiation, the chemical 4,4' (5-chloro-2-thenilidene) bis [N,N-dimethylaniline], a derivative of the leuco triarylmethane compounds was used. This chemical dosimeter is an aqueous solution composed of 10(-4) M leuco compounds, 10(-4) M ferrous ammonium sulfate, 10(-4) M sodium chloride and 7 X 10(-3) M of hydrochloric acid. This solution is colourless but it becomes blue-green or bright blue after irradiation. The optical density of this solution at the main absorption peak of 635 millimicron increases linearly with the increasing x-ray dose of from 50R to 2,000 R and no dose-rate dependence is found from 13.5 R/min to 270 R/min of 60Co gamma-ray, 896 gram rads was the measured value of the integral absorbed dose per exposure in panoramic tomography (Orthopantomograph type OP-2).

Aniline Compounds↗