Racemization studies in peptide synthesis through the separation of protected epimeric peptides by reversed-phase high performance liquid chromatography

Separation of protected epimeric peptides, Z-Gly-Xaa-Xbb-OMe (where Xaa and Xbb = chiral amino acid residues), by reversed-phase HPLC was utilized for studying racemization in peptide synthesis. Thus, the following factors which might affect the extent of racemization during the coupling by the carbodiimide method were investigated: the combination of amino acid residues to be coupled, coexisting tertiary amine salts, and the relative configuration of the amino acid residues. The following points were revealed: the combination of bulky residues at the coupling site results in extensive racemization in a polar solvent such as DMF, the amine hydrochlorides cause less racemization than the p-toluenesulfonates in DMF, and the influence of relative configuration differs depending on the solvent and the individuality of the amino components. Furthermore, the racemization-suppressing effect of some additives in the carbodiimide method was reevaluated by employing the same procedure.     

Proximal-type epithelioid sarcoma of the perineum: Calling attention of urologists

A subcutaneous mass in the perineum of a middle-aged man was excised and pathologically diagnosed at first as 'undifferentiated carcinoma' of unknown origin, which recurred 2 years later without any metastasis. Further histological evaluation ultimately established a correct diagnosis of 'proximal-type epithelioid sarcoma', a variant of rare epithelioid sarcoma. This type of tumor may confuse pathologists because its histological characteristics resemble undifferentiated carcinoma or malignant rhabdoid tumor. Frequent immunoreactivity of CD34, in addition to expression of keratins, epithelial membrane antigen and vimentin, provides strong support for the diagnosis of this rare neoplasm. Urologists should be aware that this sarcoma commonly occurs in the genital regions.     

An Approach to the Detection of Autonomic Neuropathy hy Use of Signal-Averaged Electrocardiography

The beat-to-beat variation of PR interval, which is thought to be a reflection of autonomic nervous system, is difficult to measure with accuracy because the variation is too subtle. However, R wave amplitude in the P wave triggered SAECG is easily attenuated in comparison to that in the R wave triggered SAECG, which might he due to PR interval fluctuation. To determine whether autonomic neuropathy could be detected by use of SAECG, two types of SAECGs triggered by P and R waves were recorded in 23 diabetics with autonomic neuropathy and 41 age matched controls. The peak voltage of filtered QRS complex was measured in the R wave and P wave triggered SAECGs. Percent attenuation of the filtered QRS voltage was calculated by dividing the difference between the voltages in the R wave and P wave triggered SAECGs by the voltage in R wave triggered SAECG. The percent attenuation of filtered QRS voltage was significantly smaller in diabetics with autonomic neuropathy than controls (4.6%± 4.9% vs 16.3%± 15.0%; P < 0.001). These results suggest that the degree of attenuation of filtered QRS voltage in the P wave triggered SAECG would be useful for the detection of autonomic neuropathy.     

TWO TYPES OF THYROID FUNCTION-BLOCKING ANTIBODIES IN AUTOIMMUNE ATROPHIC THYROIDITIS AND TRANSIENT NEONATAL HYPOTHYROIDISM DUE TO MATERNAL IgG

We examined the effects of IgG from four patients with autoimmune atrophic thyroiditis on cAMP responses and iodine metabolism (post-receptor processes), using cultured thyroid cells. We found two types of thyroid function-blocking antibodies: (1) one blocks TSH binding to its receptors and inhibits TSH-stimulated cAMP responses but does not block cAMP-stimulated iodine uptake and organification; (2) the other blocks TSH binding to its receptors, inhibits TSH-stimulated cAMP responses and does block cAMP-stimulated iodine uptake and organification (post-receptor processes). Among the four patients with autoimmune atrophic thyroiditis, three had TSH binding blocking antibodies only and one had antibodies which block post-receptor processes. These antibodies might be responsible for thyroid dysfunction in autoimmune atrophic thyroiditis. The daughter of one of the women with autoimmune atrophic thyroiditis had transient neonatal hypothyroidism and recovered spontaneously from the hypothyroid state with the disappearance of the maternal blocking antibodies.     

A Case of Inflammatory Bowel Disease Accompanied by Myasthenia Gravis

Abstract: A 62-year-old female visited our unit complaining of persisting diarrhea. She underwent a thymectomy for myasthenia gravis (MG) and a thyroidectomy for malignancy at age 58, and she was treated medically for MG fbllowing surgery. She also received a partial ileo-colectomy because of an intramural suppurative abscess of the terminal ileum at age 60. In her laboratory data, the anti-acetylcholine receptor antibody and antinuclear antibody were positive, and IgG as well as IgA were a high titer. X-ray and endoscopic examinations revealed the presence of stiff and narrow lesions accompanied by longitudinal ulcers of the descending colon, and rough and granular mucosa of the rest of the colon and stomach. An elemental diet was not effective, but her condition was relieved by the oral administration of prednisolone. This case was considered a case of inflammatory bowel disease ac-companied by MG and systemic immunological disorders.     

Application of a Circular Polarizing Device to an Electronic Endoscope for the Purpose of Prevention of Catch-Light Phenomenon

Abstract: In recent years the electronic endoscope has been increasingly used by medical practitioners in Japan. However, it has been noted that the problem of too strong light refection, which, not only hampers the procedure but also causes eye exhaustion, at the same time making photographic or computerized image processing difficult, is more frequently experienced and is more serious in magnitude when compared with using a conventional fiberoptic endoscope (catch-light phenomenon). In order to ameliorate this problem the authors experimented with the use of circularly polarized light. The combined use of a circular polarizing device to the efferent light path and a filter which blocks certain types of Circularly polarized light to the afferent path has proved to be very effective in eliminating the incidence of catch-light troubles, thus making the endoscopic procedure smooth and efficient.