Biogeography and adaptation in the Kuril Islands, Northeast Asia.

The Circumpolar North is generally recognized as a challenging environment to inhabit and yet, we know relatively little about how people managed their welfare in these places. Here, we add to the understanding of maritime hunter-gatherers in the subarctic North Pacific through a comparative approach that synthesizes biogeographic and archaeological data from the Kuril Islands. We conclude that our faunal, ceramic and lithic evidence support expectations from biogeography as assemblages from low biodiversity and insular regions show limited diet breadth, more locally produced pottery and a conservation of lithic resources. However, we highlight that these ecological factors did not strictly determine the occupation history of the archipelago as radiocarbon data suggests all regions experienced similar demographic fluctuations regard-less of their biogeography. These results imply additional pressures influenced the strategic use and settlement of the Kuril Islands and the need for increased chronological resolution to disentangle these complex historical factors.

Corpus callosum in patients with obsessive-compulsive disorder: diffusion-tensor imaging study.

PURPOSE: To prospectively examine microstructural white matter abnormalities in the corpus callosum (CC) of patients with obsessive-compulsive disorder (OCD), as compared with control subjects, and to investigate the relationship between diffusion-tensor (DT) imaging measures of the CC region and clinical symptoms of OCD. MATERIALS AND METHODS: Institutional review board approval was obtained, and each participant--or the participant's parent(s)--provided written informed consent. Sixteen patients with OCD (seven male, nine female; mean age, 28.7 years +/- 9.8 [standard deviation]) and 16 matched healthy volunteers (control subjects) (seven male, nine female; mean age, 29.9 years +/- 9.0) were examined. Mean diffusivity and fractional anisotropy (FA) were measured in five subdivisions of the CC. The paired t test was performed to compare the mean diffusivity or the FA in CC regions between the patients with OCD and the control subjects. RESULTS: There were no significant differences (rostrum, P = .15; genu, P = .88; rostral body, P = .12; isthmus, P = .77; splenium, P = .88) in mean diffusivity between the patients with OCD and the healthy volunteers. A significant reduction in FA was observed in the rostrum of the CC in patients with OCD compared with the rostral FA in the control subjects (P < .001). Higher FA in only the rostrum correlated significantly with lower Yale-Brown obsessive-compulsive scale score (r = -0.72, P = .002). CONCLUSION: Study results support the widely held view that the orbital prefrontal region is involved in the pathophysiology of OCD and indicate that the orbitofrontal circuit influences symptom severity in patients with OCD.

Olanzapine increases grey and white matter volumes in the caudate nucleus of patients with schizophrenia.

There are inconsistent reports regarding the caudate nucleus volume in patients with schizophrenia compared with healthy subjects. The reason for this is that neuroleptic medication may affect the volume of the caudate nucleus in schizophrenic patients. To clarify which antipsychotic medication changes the volume of the caudate nucleus in patients with schizophrenia, we measured the volumes of grey and white matter in the caudate nucleus of schizophrenic patients. Ten patients with schizophrenia were examined twice by magnetic resonance imaging (MRI) to measure the grey and white matter volumes in the caudate nucleus. After the first MRI examination, all the patients were treated with olanzapine. The clinical responses were evaluated by the positive and negative rating scale. When the symptoms improved, the patients were examined by a second MRI scan. Ten healthy control subjects also underwent MRI. The schizophrenic patients had reduced volumes of grey and white matter in the caudate nucleus compared to the healthy control subjects. The volumes of grey and white matter in the caudate nucleus of the schizophrenic patients increased after treatment with olanzapine. These findings suggest that treatment with olanzapine may increase the grey and white matter volumes in the caudate nucleus in patients with schizophrenia.

Cerebellar posterior superior vermis and cognitive cluster scores in drug-naive patients with first-episode schizophrenia.

Previously, we performed an MRI study that revealed smaller volumes of the subregions of the cerebellar vermis in men and women with chronic schizophrenia. An issue that arose from that study was whether similar structural changes in the cerebellum are found in patients with first-episode schizophrenia. In the present study, MRI scans were acquired from 14 drug-naive patients with first-episode schizophrenia and 16 healthy subjects, and used to measure the volumes of their cerebellar subregions. Positive symptom, negative symptom and cognitive cluster scores were attained using the Positive and Negative Syndrome Scale. Patients with first-episode schizophrenia had reduced volumes of the anterior vermis and posterior superior vermis compared with healthy subjects. We confirmed that there was a volume reduction of the cerebellar vermis in drug-naive patients with first-episode schizophrenia. Smaller volumes of the posterior superior vermis were associated with worse cognitive cluster scores in patients with first-episode schizophrenia.

Neural disorganization in the superior cerebellar peduncle and cognitive abnormality in patients with schizophrenia: A diffusion tensor imaging study.

Disconnection in the frontal-thalamic-cerebellar circuit is thought to be associated with cognitive abnormality in patients with schizophrenia. The superior cerebellar peduncle is involved in neural connectivity in the circuit. Because diffusion tensor imaging (DTI) can detect neural disconnection, we investigated whether there was neural disruption in the superior cerebellar peduncle in patients with schizophrenia. DTI was performed in 21 schizophrenic subjects and 21 age- and sex-matched healthy subjects. Cognitive cluster scores were attained by using the Positive and Negative Syndrome Scale (PANSS). Schizophrenic subjects had significantly lower fractional anisotropy (FA) in the right and left superior cerebellar peduncles than healthy subjects. Higher FA in the left superior cerebellar peduncle was associated with worse cognitive function in patients with schizophrenia. These findings suggest that there is neural disruption in the superior cerebellar peduncle in patients with schizophrenia, which may be involved in the cognitive abnormalities found in schizophrenia.

Reduced white matter volume of the caudate nucleus in patients with schizophrenia.

To examine volumetric abnormality, the caudate nucleus was measured in patients with schizophrenia and healthy subjects using magnetic resonance imaging. The absolute and relative volumes of white matter in the caudate nucleus were found to be significantly smaller in patients with schizophrenia compared to those in healthy subjects. There were significant correlations between dosages of neuroleptics during the previous year and absolute gray matter volumes of the caudate nucleus as well as relative white matter volumes in patients with schizophrenia. These findings suggest that reduced white matter volume of the caudate nucleus may be a factor affecting the abnormal connectivity of the corticostriatal loop, and that neuroleptic medication would be related to white matter alteration in patients with schizophrenia. Our result replicates a previous study reporting that there is a lack of negative correlation between age and caudate nucleus volume. We also suggest that the disease process of schizophrenia might interfere with normal aging.

Subtle disruption of the middle cerebellar peduncles in patients with schizophrenia.

Diffusion tensor imaging (DTI) was used to investigate subtle disruption in the middle cerebellar peduncles in patients with schizophrenia. Fractional anisotropy (FA) was measured in 25 patients with schizophrenia and 21 healthy subjects using DTI. The FA of the right and left middle cerebellar peduncles was significantly lower in the schizophrenic patients compared to healthy subjects. FA in the left middle cerebellar peduncles was significantly correlated with the dosage of neuroleptics in patients with schizophrenia. There were no significant differences of mean diffusivity in the right and left middle cerebellar peduncles between patients with schizophrenia and healthy subjects. The findings of the study suggest that antipsychotics may improve the subtle disruption in the middle cerebellar peduncles in patients with schizophrenia.

Enhancement of IL-7 following irradiation of fetal thymus.

The effect of ionizing radiation on intra-thymic T cell development was investigated using a fetal thymic organ culture (FTOC) method in vitro. When double-negative (DN) fetal (day 15) thymocytes were co-cultured with an irradiated (25 Gy) fetal (day 15) thymus in the absence of direct contact or mitogenic stimulation, the induction of TCRgammadelta+ T cells was observed. About 50% of the TCRgammadelta+ T cells developed after 4-day-co-culture with the irradiated fetal thymus, whereas only a few TCRgammadelta+ T cells developed after co-culture with the non-irradiated fetal thymus. About 50% of the TCRgammadelta+ T cells were CD8+ cells with alphabeta heterodimeric chains. Cultured supernatants of the irradiated fetal thymi also induced the differentiation from DN thymocytes to CD8+ TCRgammadelta+ T cells after 3-day-culture. To clarify the factor in the cultured supernatants, several neutralizing antibodies (Abs) were used. Only anti-IL-7-Ab inhibited the differentiation from DN thymocytes to CD8+ TCRgammadelta+ T cells. RT-PCR revealed the increased expression of IL-7 mRNA in the fetal thymus 24 hours after radiation. Electron microscope studies demonstrated proliferative epithelial cells in the irradiated fetal thymus. These findings strongly suggest that fetal thymic epithelial cells affected by irradiation proliferate and enhance the production of IL-7, which induces the differentiation of CD8+ TCRgammadelta+ T cells from DN thymocytes.

Inter- and intraoperator reliability of brain tissue measures using magnetic resonance imaging.

Grey matter, white matter and cerebrospinal volume in the human brain were measured using magnetic resonance image analysis software BRAINS. Ten volunteers were scanned in the MR sequence (3D-SPGR; 1.5-mm slice thickness and T2 images; 3mm slice thickness). Two operators obtained ten volume measures of grey matter,white matter and cerebrospinal fluid (CSF) in the intracranial box, frontal box, temporal box, parietal box and occipital box. The same data set of ten scans was segmented and the volumes measured on a second occasion by one operator using the same procedure. The interoperator and intraoperator reliabilities for measures of the three brain tissues were very good, with reliability coefficients (intraclass correlation coefficients) ranging between 0.971 and 0.999. The segmentation and measurement are useful for volumetric studies in the human brain using BRAINS.