Search

N-Ethyl-N-nitrosourea (ENU) induces recessive mutations (RM) at a high frequency in male mouse primordial germ cells (PGCs)　in a dose-dependent and stage-specific manner when administered during embryonic development as confirmed by a specific locus test (SLT) (Shibuya et al., 1993, 1996 [1,2]). ENU also induces intragenic recombination (IGR) in the p un allele at E10.5 in PGCs of male mice (Shibuya et al., 2022 [3]). In this study, the induced mutant frequencies (MF) in testicular cells of male Muta™Mousetreated at the same developmental stages of PGCs were determined with a positive selection system (MM/PS). Although the mutant frequencies　of MM/PS were consistently lower than for the SLT/RM, they showed similar stage-specificity and dose-dependency. Expressed as a linear equation, the correlation coefficient on the MF from SLT and MM/PS was extremely high (r 2 = 0.920)., (Copyright © 2022. Published by Elsevier B.V.)

The forward or reverse processes of intragenic recombination (IGR), which occur through the addition or deletion of duplicated homologous exons of the p un allele in Pun mice, was observed in vivo, after introducing an homozygous p un allele in a C57BL/6 background. We assessed the frequency of IGR upon N-ethyl-N-nitrosourea (ENU) treatment of pre-melanocytes (PMCs: somatic cells) and primordial germ cells (PGCs: germ cells) of embryonic mice at 10.5 days of development (E10.5). We simultaneously examined IGR and other mutations at the p locus of PMCs responsible for coat color in the offspring obtained by crossing p un /p un with p un /P mice. The frequencies of both spontaneous and ENU-induced IGR were markedly higher than that of the recessive mutation (RM) in PMCs obtained from crossing C57BL/6 and PW strains (Shibuya et al., 1982). ENU also induces IGR at a higher frequency in PGCs at E10.5, which was observed in the next generation. These results indicate that ENU, which preferentially induces gene mutations through base substitution, also induces IGR at a high frequency in the p un allele in both somatic and germ cells of embryonic mice at the E10.5 developmental stage., (Copyright © 2021. Published by Elsevier B.V.)

Introduction: Spinal injuries resulting from entering into water usually occur in the cervical region, with few reported in the thoracolumbar region. Although the mechanism of cervical spine injury caused by diving is known, less is known regarding the mechanism of upper lumbar spine injury., Materials and Methods: The study subjects were five patients (mean age, 32.8 years), inexperienced in diving from heights, who were referred for burst fractures (Denis type B) at L1 caused while jumping into a river from a 12-m-high bridge between 2004 and 2005. Three patients were treated surgically and two were treated conservatively. Their clinical outcomes were reviewed and the mechanism of upper lumbar spine injury was discussed., Results: No patient experienced neurological deficit or low back pain after treatment, and all returned to their previous activities within 1 year. Impact with the surface of the river with back and hip flexed may be a major cause of upper lumbar spine injury., Conclusions: To minimize the incidence of upper lumbar burst fracture during recreational high jumping into water, it is important that jumpers, especially inexperienced jumpers, should be instructed to jump with their backs and hips straight.

A 39-year-old woman with Graves' disease associated with follicular thyroid carcinoma underwent subtotal thyroidectomy. TSH-binding inhibitor immunoglobulins (TBII) were positive, whereas thyroid-stimulating antibodies (TSAb) and thyroid-stimulation-blocking antibodies (TSBAb) were both negative before the operation. After the operation, TBII markedly increased above the pretreatment value. TSBAb became positive 3 months after the operation and then their activity increased, while TSAb remained negative after the operation. Subtotal thyroidectomy may have influenced the development of TSBAb in this patient. Irrespective of these findings, the patient became hyperthyroid again several months after the operation.

A 42-year-old female with Graves' disease and papillary thyroid carcinoma with lung metastasis was referred to our hospital. After treatment of thyrotoxicosis with methimazole and Lugol's solution, she underwent total thyroidectomy. She was then given 131I twice to treat lung metastasis. However, 131I uptake into the lung was not clear in the scintigram. Both thyroid-stimulating antibodies (TSAb) and thyroid-stimulation-blocking antibodies (TSBAb) were detected in her sera before and after the treatments. Compared with TSAb activities, TSBAb activities were extremely high. Changes in the titers of these two antibodies were not clear after total thyroidectomy. These results indicate that lymphocytes outside the thyroid gland are the major source of TSAb and TSBAb in this patient.

A 63-year-old housewife with a history of partial thyroidectomy was referred to our hospital because of a neck mass and abdominal tumor. Aspiration biopsy of the neck tumor revealed the recurrence of papillary thyroid carcinoma. Magnetic resonance imaging (MRI) of the abdomen and urinary and plasma catecholamine levels indicated that the tumor beside the abdominal aorta was an extraadrenal pheochromocytoma. Two tumors were excised and histologic studies confirmed the diagnosis. So far two cases of extraadrenal pheochromocytoma with papillary thyroid carcinoma have been reported. The present case indicates that the presence of papillary thyroid carcinoma should be considered in patients with extraadrenal pheochromocytoma.

Reports is the case of a 21-year-old student, who received a medical examination at our Department for an abnormal chest shadow that had been detected during a periodic health examination at his university. No special subjective symptoms such as a cough and/or sputa, pyrexia, pectoralgia, and dyspnea were noted. A thyroid tumor was palpable and a 99mTc thyroid scintigram and a 201Tl thyroid tumor scintigram gave cause to suspect thyroid cancer and a metastatic lung tumor. A total thyroidectomy and a right modified neck dissection revealed a tumor (histologically, a papillary cancer), 3.5 cm in diameter, that mainly involved the right lobe. It was found that 131I-100 mCi internal irradiation was very effective for the metastatic lung tumor, and no abnormal shadow was subsequently revealed by chest X-ray. Now, 6 years later, he is alive with no manifestations of a local relapse nor any abnormal chest X-ray findings.