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We demonstrate the self-assembled formation of concentric quantum double rings with high uniformity and excellent rotational symmetry using the droplet epitaxy technique. Varying the growth process conditions can control each ring's size. Photoluminescence spectra emitted from an individual quantum ring complex show peculiar quantized levels that are specified by the carriers' orbital trajectories.

The molecular orientation of DNA membranes, which were prepared by subjecting diluted solution of salmon sperm DNA to a natural drying process, was examined. X-ray diffraction and polarization microscopy revealed that the dried membranes have zonal structures. Each zone shows different features in molecular orientation. In the outer zones formed at the early stage in drying, DNA molecular chains were found to be aligned along the annular curve of the peripheral edge. Both the uneven thickness and disproportional molecular weight distribution in a membrane suggested that the radial flow transported DNA molecules to the edge and that they formed the accumulated phase. Above the critical concentration for the formation of liquid crystalline, the DNA chains would be aligned onto the preformed solid--liquid interface. The membranes with the highest birefringence were obtained from DNA samples with the relatively high molecular weight of around 29 kbp. In the innermost zone, on the other hand, the DNA molecules were radially oriented. This alignment can be attributed to the hydrodynamic effect caused by the rapid translation of the edge interface, which overcomes the Brownian motion of the chain segments. A transitive balance of physical effects was revealed in the dry process, which provided quite orthogonal molecular orientations in a single droplet.

We have succeeded in preparation of novel composite films composed of chain-oriented DNA and the DNA-binding dyes aligned in specific orientation by drying the solution under a horizontal magnetic field. The dye-DNA composite films mostly showed linear dichroism, as revealed by polarized ultraviolet-visible spectroscopy (UV-VIS) and fluorescence anisotropy measurement. The intercalators such as ethidium bromide was fixed in chain-oriented DNA films in a similar binding manner as in solutions. Also, Hoechst 33258 was found to be aligned along the minor groove even in the solid films. In addition, by means of this film method, we could estimate the DNA-binding modes of newly designed original compounds. Here, we emphasize that the method using aligned dye-DNA films is very convenient for identifying the binding modes for double-stranded DNA.

DNA films showing highly homogeneous orientation of molecular chains were successfully prepared by drying a semidiluted solution in a horizontal magnetic field. Most of the molecular chain elements in the obtained film were found to be one-dimensionally oriented, as shown by X-ray diffraction, polarization microscopy, and linear dichroism spectroscopy. Because a DNA chain is theoretically expected to orientate only in divergent directions perpendicular to a magnetic field, this result suggests that the DNA chains were aligned not only by a magnetic field but also by the interfacial effect that induced the chains to fit along the air-liquid interface. The descent speed of an air-liquid interface by evaporation was faster than the estimated diffusion rate of DNA, suggesting an emergence of a concentrated layer near the surface. As proved by polarization microscopy, this emergence led to the transitional formation of a nematic-like liquid crystalline phase, which resulted in a DNA film with good chain alignment and unitary orientation. This mechanism underlying chain alignment was supported by molecular weight dependency, in which higher molecular weight DNA is more likely to evince chain alignment that exhibits a higher degree of birefringence. Low molecular weight components have such high thermal motility that it would be difficult to fit them along the air-liquid interface in the early stage of drying. For chain alignment, it was preferable to use an initial concentration of DNA lower than a critical concentration for liquid crystal formation so that the possible diffusion and assembly in a diluted solution would be essential for chain alignment. The DNA film exhibited obvious linear dichroism, indicating the potential for further applications.

Magnetic phase diagrams for antiferroquadrupole (AFQ) phase II and antiferromagnetic (AFM) phase III in Ce0.50La0.50B6 with a Gamma(8) ground state have been investigated by ultrasonic measurements. The hybrid magnet (Gama) in the National Institute for Materials Science was employed for high-field measurements up to 30 T and a 3He-4He dilution refrigerator was used for low-temperature experiments down to 20 mK. The phase boundary from paramagnetic phase I to AFQ phase II under [001] magnetic fields closes at H(I-II) approximately 29 T, while the boundary is still open under fields along the [110] and [111] directions even up to 30 T. This anisotropic character of phase II in fields is consistent with the theoretical calculation based on the O(xy)-type AFQ ordering. We also found that AFM phase III reduces considerably in fields turning from the [001] to [110] and [111] directions.

Phase manipulation between c(4x2) and p(2x2) on the Si(100) surface has been demonstrated at 4.2 K for the first time using a low-temperature scanning tunneling microscope. We have discovered that it is possible to change the c(4x2) surface into the p(2x2) surface, artificially, through a flip-flop motion of the buckling dimers by using a sample bias voltage control. Also, scanning at a negative bias voltage or applying a pulse voltage can restore the c(4x2) surface. The STM images as a function of bias voltage and tunneling current reveal the interesting dynamics of the buckling dimers on the long debated surface. Our results will show that energetic tunneling electrons are most likely responsible for the observed phase transition from c(4x2) to p(2x2).

Five cases of von Hippel-Lindau disease in two families were reported. In one family there were 2 cases in a mother (55 years old) and her daughter (26 years old) which had multiple hemangioblastomas in the optic nerve, cerebellum and spinal cord in each case. Retinal angioma appeared in the case of daughter, but not in the mother. In the other family there were 3 cases in a father (28 years old), his son (11 years old) and daughter (14 years old). All of them had retinal angioma and cerebellar hemangioblastoma. Two cases out of 5 cases in the two families were associated with abdominal organ diseases which were renal cell carcinoma in a case and pancreas cyst in the other. The familial occurrence of von Hippel-Lindau disease in Japan was recognized in 21 families with 103 cases including our cases. On the study of reported cases hemangioblastoma frequently occurred in multiple region such as cerebellum, medulla oblongata and frequently presented with renal cell carcinoma, pheochromocytoma and cyst in pancreas, kidney and liver. The location of hemangioblastoma and combined disease was similar in cases in each family. The age of onset of von Hippel-Lindau disease in the second generation was younger than that of the first generation.

Authors have studied 128 cases of meningiomas which were operated on and examined histologically. 12 cases (11.3%) of 106 cases of the meningiomas followed up for more than 5 years after surgery had recurrence after the primary operation. The distribution of age and sex, the tumor location, the histological type, the extent of tumor evacuation and AgNORs counts and BrdU labeling index for the evaluation of tumor proliferation were studied comparatively in the two groups, the recurrent and nonrecurrent meningiomas. 8 cases (19.0%) of 42 cases of the meningiomas in the age-group lower than 50 years old were recurrent cases, whereas 4 cases (6.0%) of 67 cases in the age-group over 50 years old were non-recurrent. Concerning the sex distribution of the meningiomas in our cases recurrent rate was 20.5% among males and 6.0% among females. The tumor locations of the meningiomas did not correlate significantly with recurrence. The extent of tumor removal demonstrated Simpson grade I (47 cases), grade II (37 cases), grade III (17 cases), grade IV (5 cases) on primary operation. Recurrence was found in 11 cases (13.1%) of 84 cases operated on by total removal of Simpson grade I or grade II. 8 cases of 11 cases had recurrence within 5 years after the primary operation of Simpson grade I or II. Total removal of the tumor was important in order to bring about long survival after operation. But correlation between the extent of tumor removal and recurrence was not able to be recognized. Histologically, all of the malignant, atypical and papillary type of meningiomas treated in the primary operations had recurrence.(ABSTRACT TRUNCATED AT 250 WORDS)

Turner's syndrome, a sex-chromosome abnormality, is often accompanied by cardiovascular disorders, such as coarctation of the aorta. We encountered a case of Turner's syndrome with meningioma and pituitary hyperplasia which resulted in death from dissection of the aorta. The patient was 36-year-old female who was diagnosed as having Turner's syndrome of mosaic-type at the age of 15. She had accepted sex-hormone replacement with estrogen and progesterone over 20 years. She lost consciousness and was transferred to our institute on June 20th, 1992. She was in shock but her condition began to improve after intensive treatment. CT scan revealed a calcified mass lesion at the left frontal convexity and a markedly enhanced round mass lesion at the suprasellar region. Angiography showed tumor stain of the suprasellar region fed by the posterior ethmoidal artery. These tumors were diagnosed as multiple meningiomas. She developed dyspnea on June 24th and chest X-ray showed right pleural fluid collection and cardiomegaly. This condition was diagnosed as congestive heart failure. Her condition was getting worse and she suffered abrupt cardiac arrest on June 28th. Autopsy revealed dissection of the aorta as the cause of death. The tumor of the convexity was meningioma, and the suprasellar lesion was diagnosed as pituitary hyperplasia. It is well known that frequent excess dose injection of estrogen can induce pituitary adenoma or hyperplasia in rats. In this case, the presence of pituitary hyperplasia was thought to be the result of long-term injection of estrogen.(ABSTRACT TRUNCATED AT 250 WORDS)

A rare pituitary adenoma associated with Rathke's cleft cyst was discovered incidentally in a 44-year-old male admitted after head trauma. Neurological and physiological examination found no abnormalities, except for panhypopituitarism. Computed tomography and magnetic resonance imaging demonstrated a solid mass in the sellar cavity with suprasellar extension, associated with a cystic mass extending into the third ventricle. The tumor was removed subtotally by the transcranial approach. Light microscopy demonstrated that the cyst wall was composed of ciliated columnar cells, cuboidal cells, and goblet cells, and the solid part indicated chromophobe pituitary adenoma. Immunohistochemistry demonstrated that a few adenoma cells were positive for prolactin and the cyst wall cells were positive for cytokeratin and negative for S-100 protein.

The authors present a case of central neurocytoma in a 23-year-old male with increased intracranial pressure syndrome. Computed tomographic (CT) scans and magnetic resonance images showed a large tumor mass with no evidence of calcification in the right lateral ventricle extending towards the third ventricle. A right transcortical-transventricular approach was performed and the tumor was totally removed. The postoperative course was uneventful and no further treatment was administered. CT shows no evidence of tumor recurrence after the six months from his surgery. Light microscopic findings suggested a diagnosis of oligodendroglioma. However, ultrastructural examinations demonstrated many dense-core or clear vesicles, microtubules and synaptic like structures within the abundant cytoplasmic processes of the tumor cells which suggested neuronal differentiation. Immunohistochemical examinations showed the tumor cells to be positive for neuron-specific enolase, sporadically positive for synaptophysin, and negative for glial fibrillary acidic protein. The final histological diagnosis was central neurocytoma. Central neurocytoma was first described by Hassoun et al, in 1982. Since then, 96 cases have been reported in the literatures. Their clinicopathological features, neuroradiological findings and prognosis are discussed.

The effects of intravenous (IV) infusion of human recombinant tumor necrosis factor-alpha (rTNF-alpha, Cetus) on normal brain and malignant glioma in rats were examined. Twelve Fischer 344 rats were given either a single injection of 10(6) U rTNF-alpha or injections of 5 x 10(5) U rTNF-alpha for three days. One day post-rTNF-alpha injection(s), rats were injected IV with horseradish peroxidase (HRP) to determine blood-brain barrier (BBB) breakdown and, one hour later, were perfused with an aldehyde fixative and processed for histologic examination. Treatment of normal rats with rTNF-alpha by either dosage or schedule caused no remarkable histopathologic changes in the brain and no alteration in BBB integrity. Human glioma models were produced by intracerebal inoculation of 10(4) syngeneic RT-2 glioma cells into the right parietal lobe of 30 rats. Animals received single IV injections of 10(6) U human rTNF-alpha or its excipient (TNF-E) as above on day 3, 7, or 10 post-tumor inoculation or multiple injections of 5 x 10(5) U rTNF-alpha beginning on day 7, 10, or 12 post-tumor inoculation. With a single IV injection of either rTNF-alpha or its excipient, 3-day models showed a similar pattern of HRP extravasation limited to the extracellular space of the tumor inoculation site. In 7-day models treated with a single IV injection of rTNF-alpha or TNF-E, HRP extravasated throughout the tumor, but did not exceed peritumoral margins. In 10-day models treated with a single injection of TNF-E, HRP was found only in the tumor and immediate peritumoral regions while rTNF-alpha-treated rats showed more extensive areas of BBB breakdown with HRP evident throughout the entire right hemisphere and extending via the corpus callosum into the contralateral hemisphere. Pericapillary halos were also evident around the small blood vessels within the edematous areas of the corpus callosum. Within tumors, hemorrhagic necrosis and adherence of neutrophils to vessels was observed only in animals treated with rTNF-alpha at 10 days post-tumor inoculation. Multiple IV injections of rTNF-alpha in 7 and 10-day models triggered widespread hemorrhagic necrosis, neutrophil adherence and infiltration in the tumor. There was also extravasation and diffusion of HRP from the site of glioma into the contralateral hemisphere. Twelve-day models treated with multiple rTNF-alpha injections, in addition, showed irregular luminal surfaces and gaps between adjacent endothelial cells of tumor vasculature.(ABSTRACT TRUNCATED AT 400 WORDS)

The effect of sphingosine, a known selective inhibitor of protein kinase C, on the induction of tyrosine aminotransferase (TAT) and tryptophan oxygenase (TO) by dexamethasone was studied in the primary culture of rat hepatocytes to determine the possible involvement of protein kinase C in the expression of glucocorticoid action. Sphingosine inhibits the induction of TAT by dexamethasone in a concentration- and time-dependent manner in primary culture of rat hepatocytes. It does not inhibit the induction of TAT by Bt2cAMP. Sphingosine inhibits also the induction of TO by dexamethasone in a manner similar to TAT inhibition. It has no effect on the activity of lactate dehydrogenase, a cytosolic marker enzyme and on the protein content of the cultured hepatocytes. These findings indicate that endogenous modulator of protein kinase C, such as sphingosine, may influence the expression of glucocorticoid action in rat hepatocytes.

Regional cerebral turnover of 11C following intravenous injection of 11C-1-pyruvate was investigated in 12 patients with brain tumors. The positron emission tomography (PET) image taken at 10-15 min after the injection always demonstrated a high concentration of 11C in tumor, and thus visualized precise tumor contours. This phenomenon was not influenced qualitatively by the variation of blood flow in the tumor. Brain edema associated with the tumor was not visualized. We conclude that the localization of brain tumors would be well determined by the PET scan, using 11C-1-pyruvate.

Occurrence of tumor of pineal region in three brothers was presented and previously reported cases of familial occurrence of primary intracranial tumor were reviewed. Two cases were diagnosed as germinoma clinically. The other case was diagnosed as embryonal carcinoma by pathohistological examination. All cases were of germ cell tumor. Reports of pineal tumors occurring in siblings are extremely rare. There have been three reports in the literature but no case of familial occurrence of histologically verified germ cell tumor in the pineal region in three siblings has been reported. Genetic aspects of primary intracranial tumors have been discussed but there has not been established a close relationship between heredity and oncogenecity. This case is a very interesting case because it is not only a rare case of familial occurrence of pineal tumor but it suggests the propriety of the theorum dealing with germ cell origin tumor.

To clarify functional neural pathways originating from the thalamic nucleus ventralis posterolateralis (VPL) in humans, the responses of regional CBF (rCBF) and regional CMRO2 (rCMRO2) to VPL stimulation were investigated by positron emission tomography in five patients who had undergone chronic implantation of electrodes into the VPL for therapeutic purposes. Measurement of rCBF and rCMRO2 under continuous inhalation of C15O2 and 15O2 by steady-state methods revealed significant increases of rCBF and rCMRO2 in the frontal, postcentral, and thalamic regions. The increases in rCBF and rCMRO2 of the postcentral regions were clearly predominant in the stimulated hemisphere insofar as the stimulation produced moderate paresthesia in restricted areas of the body. These results indicate that the VPL relays peripheral somatosensory information, which has previously been demonstrated to be transmitted to the frontal as well as postcentral regions.