Search PubMed⌕ Search

Biomedical subjects

C Yamanaka

Publications and source records attributed to C Yamanaka.

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

Changes in the ganglioside composition of human neuroblastoma cells under different growth conditions.

The ganglioside composition of human neuroblastoma cells (LA-N-1 and LA-N-5) was studied in samples obtained from (1) original cells in tissue cultures, (2) tumors grown in nude mice inoculated with original cells and (3) cells in tissue cultures re-established from the mouse tumors. The amounts of "a" pathway gangliosides (GM2, GM1 and GD1a) and those of the "b" pathway (GD3, GD2, GD1b and GT1b) differed according to the culture conditions. The "b" pathway gangliosides were markedly increased in the tumors grown in nude mice. In contrast, the "a" pathway gangliosides were abundant in cultures of both original and re-established cells. We also measured the enzymatic activities of UDP-N-acetylgalactosamine: GM3, N-acetylgalactosaminyl transferase (EC 2.4.1.92) and of CMP-N-acetylneuraminic acid: GM3 sialyl transferase (EC 2.4.99.8) in neuroblastoma cells cultured under these conditions. These enzymes are thought to be the key enzymes involved in the synthesis of the "a" and "b" pathway gangliosides. Though there was no significant difference in the activity of N-acetylgalactosaminyl transferase between original cells and tumors in nude mice, re-established cells showed a definitely higher activity (3.5 times higher than in the original cells). On the other hand, tumors grown in nude mice had a markedly higher activity of sialyl transferase than that of original cells or re-established cells. These findings suggest that the culture conditions and/or the type of cell growth play some role in the synthesis and expression of gangliosides in neuroblastoma cells.

Animals↗
PubMed1990

Neurohypophyseal function of an ectopic posterior lobe in patients with growth hormone deficiency.

We studied the neurohypophyseal function of 20 patients with complete GH deficiency owing to pituitary stalk transection by means of the water deprivation and the hypertonic saline infusion test. In T1-weighted magnetic resonance images, high-signal intensity of the posterior lobe of the hypophysis was missing in all the patients. An ectopic posterior lobe was observed at the proximal stump of the transected stalk in 17 patients, whereas the 3 patients without ectopic posterior lobe had overt diabetes insipidus or intractable nocturnal enuresis. After water deprivation, 3 patients with large ectopic posterior lobes (length along the pituitary stalk axis exceeding 5 mm) showed urinary osmolality and plasma AVP levels as high as those of 13 patients with partial GH deficiency in whom magnetic resonance images revealed no abnormalities. On the other hand, 14 patients with small ectopic posterior lobes (length less than 5 mm) showed significantly lower urinary osmolality and plasma AVP levels than the patients with large ectopic posterior lobes (p less than 0.01 and p less than 0.01, respectively) and the patients with partial GH deficiency (p less than 0.01 and p less than 0.01, respectively). Urinary osmolality in the patients with small ectopic posterior lobes, however, was higher than that in 3 patients without ectopic posterior lobes (p less than 0.01). During the hypertonic saline infusion test, peak plasma AVP levels in the patients with small ectopic posterior lobes were significantly lower than those in the patients with partial GH deficiency (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Wilms tumour in a patient with growth hormone replacement therapy.

Wilms tumour was found in a Japanese boy aged 5 years 9 months with isolated growth hormone (GH) deficiency and some congenital anomalies. He had received pituitary GH replacement therapy from the age of 2 years 1 month to 4 years 7 months and after a 1 year interval he received biosynthetic GH for 2 months until the tumour became clinically apparent. This was the sixth known patient with GH deficiency to develop a malignant neoplasm during or after GH replacement therapy and the first with a solid tumour in Japan since 1975, when treatment with pituitary GH for patients with GH deficiency was introduced.

Child, Preschool↗
PubMed1989

Developmental changes of plasma ganglioside concentration during the neonatal period.

We investigated the developmental changes of plasma ganglioside concentration during the neonatal period. The mean plasma ganglioside concentration at birth was 8.22 +/- 3.70 nmol lipid-bound sialic acid (LBSA)/ml, significantly lower than the value in adults (12.05 +/- 1.36 nmol LBSA/ml, P less than 0.02). However, it increased rapidly early in the neonatal period and reached its maximum level at 14 days of age (16.25 +/- 6.04 nmol LBSA/ml), which was higher than that of adults (P less than 0.05); then it decreased slowly to the adult level at one month of age. The mean plasma ganglioside concentration in preterm infants (gestational age less than 37 weeks) was 6.65 +/- 3.35 nmol LBSA/ml, somewhat lower than that of fullterm infants (gestational age greater than or equal to 37 weeks, 9.90 +/- 3.39 nmol LBSA/ml, P less than 0.02) at birth. After birth, it increased much more rapidly in preterm infants and there was no significant difference between these two groups at 5 days of age. Plasma ganglioside concentration at birth increased gradually in correlation with gestational age. Our investigations show that plasma ganglioside concentration may reflect the development and maturation of the central nervous system to some degree, at least early in the neonatal period.

Adult↗
PubMed1989

Y chromosome specific DNA probe in the diagnosis of a patient with mos 45,X/46,XYnf.

In a patient with mos 45,X/46,XYnf, the diagnosis was confirmed with a Y chromosome-specific DNA probe, Y-190. The patient was a phenotypic female without Turner syndrome stigmata other than short stature. She showed some evidence of virilization and high serum testosterone. Her peripheral blood karyotype was mos 45,X/46X, +mar. Although this marker chromosome resembled a Y chromosome, there was no quinacrine bright region on its long arm. Southern blot analysis of her peripheral blood mononuclear cell DNA with Y-190 as a probe showed strong hybridization with this probe. Gonadectomy was performed, and bilateral gonadoblastomas were found.

Adolescent↗
PubMed1989

[Basilar bifurcation aneurysm associated with internal carotid artery occlusion. Report of two cases].

Two cases of subarachnoid hemorrhage caused by rupture of a basilar bifurcation aneurysm associated with occlusion of the internal carotid artery (ICA) at the neck are presented. Case 1, a 71-year-old female, was hospitalized in a coma. Angiography demonstrated occlusion of the bilateral ICA, collateral blood supply through the branches of the foramen rotundum or vidian artery from the maxillary arteries and right posterior communicating artery, and a saccular aneurysm at the basilar bifurcation. The patient died 1 month later following rerupture of the aneurysm. Case 2, a 64-year-old male, was hospitalized for drowsiness. Angiography showed occlusion of the right ICA, collateral blood supply through a tortuous artery (a vidian artery), and a large aneurysm at the basilar bifurcation. Posterior circulation supplied anteriorly through the right posterior communicating artery. The patient died 1 month later because of rerupture of the aneurysm. Laminar thrombosis of the right ICA and an anastomotic vessel, seemingly a branch of the foramen rotundum or a vidian artery, were demonstrated by autopsy. The combination of cerebral aneurysm and collateral circulation is extremely rare in cases of occlusion of the ICA. The two cases described here suggest that hemodynamic stress is an important factor in the formation of cerebral aneurysms.

Aged↗
PubMed1988

Hypothalamic-pituitary function in growth hormone-deficient patients with pituitary stalk transection.

We compared 1.5 T magnetic resonance (MR) image findings with hypothalamic-pituitary function in 11 patients with idiopathic pituitary dwarfism, each of whom had a history of perinatal abnormalities, and 1 patient with posttraumatic pituitary dwarfism. MR imaging revealed transection of the pituitary stalk in all patients and the formation of an ectopic posterior lobe at the proximal stump in 9 patients, none of whom had polydipsia or polyuria. Three patients without an ectopic posterior lobe had diabetes insipidus. The 5 patients who had small pituitary glands (less than 2 mm in height) had hypothyroidism with low serum TSH concentrations and low serum cortisol responses to insulin-induced hypoglycemia; however, 7 patients with normal-sized pituitary glands had normal thyroid and adrenal function. The serum GH response to GHRH did not correlate with the size of the pituitary gland. The patients with small pituitary glands had delayed or prolonged serum TSH responses to TRH and impaired serum LH and FSH responses to GnRH; 4 of the patients with normal-sized pituitary glands had normal serum TSH, LH, and FSH responses. Only 2 patients had high basal serum PRL concentrations. The endocrinological data suggest that reestablishment of the hypothalamo-hypophyseal portal circulation, which cannot be seen by MR imaging, may occur. We suggest that the primary cause of idiopathic pituitary dwarfism in many patients is injury to the pituitary stalk at birth.

Adolescent↗
PubMed1988

Nocturnal urinary growth hormone excretion in children with short stature.

Nocturnal urinary growth hormone levels in children with short and normal stature were measured by a sensitive enzyme immunoassay. Urinary GH excretion during sleep correlated positively with peak plasma GH values during pharmacological (r = 0.74, P less than 0.001) and sleep (r = 0.85, P less than 0.001) tests. The amounts of urinary GH excretion during sleep differed significantly from each other in the following groups: complete GH deficiency (mean +/- SEM: 0.1 +/- 0.1 ng/m2 of body surface area; range: less than 0.1-0.4), partial GH deficiency (1.6 +/- 0.3 ng/m2; 0.2-3.1), and short stature without GH deficiency (3.7 +/- 0.6 ng/m2; 0.7-11.5). No significant difference was found between short stature without GH deficiency and normal stature (5.0 +/- 0.5 ng/m2; 2.1-10.5). Measurement of nocturnal urinary GH excretion is a simple method for screening of GH excretion and may be helpful in the differentiation of the various etiologies of short stature in children.

Adolescent↗
PubMed1987

Basilar bifurcation aneurysm associated with bilateral internal carotid occlusion.

A case of subarachnoid hemorrhage from ruptured aneurysm of the basilar bifurcation associated with occlusions of both internal carotid arteries at the neck is presented. Each internal carotid artery mainly received collateral flow at the cavernous portion from the internal maxillary artery through anastomotic artery of the foramen rotundum. Posterior circulation also supplied collateral blood flow via the right posterior communicating artery. This case report suggests that hemodynamic stress may be regarded as an important factor in the formation or development of cerebral aneurysm.

Aged↗