Source localization of posterior slow waves of youth using dipole modeling

AIM

Posterior slow waves of youth have a well-known electroencephalographic pattern that peaks in adolescence and usually disappears in adulthood. In general, posterior slow waves of youth are regarded as normal, but some reports have suggested that their presence is related to immature personalities or inappropriate social behavior. The physiological significance of this electroencephalographic pattern, however, remains unclear. The purpose of this study was to investigate the neural origins of posterior slow waves of youth using dipole source modeling.

METHODS

Electroencephalographic epochs, including clear posterior slow waves of youth, were visually selected from electroencephalograms obtained from six normal adolescents using 25 scalp electrodes. The selected epochs were then averaged by arranging the negative peak of the slow waves at the occipital area of each epoch on the time axis. The averaged waveforms consisting of six right and one left posterior slow waves of youth were used for dipole source analysis. A single equivalent current dipole was estimated for the averaged waveforms.

RESULTS

The best equivalent current dipoles were estimated to be located in or around the fusiform and middle occipital gyrus ipsilateral to the posterior slow waves of youth.

CONCLUSIONS

The location of the estimated dipoles of posterior slow waves of youth was on the so-called ventral visual pathway. Further research is required to clarify the physiological significance of posterior slow waves of youth with respect to their origin.

Dipole source analysis of temporal slow waves in the elderly

BACKGROUND

Temporal low-voltage irregular delta-waves (TLID) are often found in elderly subjects. The physiological significance of TLID has not been clarified; however, our previous studies suggest that TLID are associated with mild cerebrovascular dysfunction.

OBJECTIVE

The present study aimed to reveal the origin of TLID and their neural mechanisms by dipole source modeling.

METHODS

From electroencephalography records taken from 21 scalp electrodes, clear and typical TLID of 6 elderly subjects (mean age, 69 +/- 6.2 years) were selected. Among these, we selected and averaged 7-12 clear TLID on the left side in each subject, and estimated a single equivalent current dipole for the averaged TLID.

RESULTS

The best equivalent current dipoles were estimated to be located in the medial part of the temporal lobe in or near the parahippocampal gyrus in the hemisphere ipsilateral to the TLID, with a high reliability in all subjects.

CONCLUSIONS

Considering the source localization of TLID, TLID seem to indicate certain dysfunctions of the hippocampus or adjacent regions. This is the first study to report the cerebral origin of TLID and suggest its physiological significance.

Late-onset depression: can EEG abnormalities help in clinical sub-typing?

BACKGROUND

The purpose of this study was to determine the frequency of EEG abnormalities indicative of mild cerebrovascular dysfunction in patients with late-onset depression and to correlate these abnormalities with clinical features.

METHODS

The subjects, aged > or = 50 years, were 51 outpatients with major depression diagnosed according to DSM-IV criteria. They were living in the community and prospectively selected at their initial consultation for mostly mild-moderate depression. We also included 32 normal age-matched controls. We examined basic rhythms and temporal slow waves on EEG and determined the Hamilton Rating Scale for Depression (HAMD) as a scale for the severity of psychiatric symptoms.

RESULTS

Temporal slow waves were more common in depressed patients (47%) than in normal controls (22%). Depressed patients with temporal slow waves had significantly lower frequency of family history of mood disorders (P<0.05). There was no difference in the total score of HAMD between patients with and without temporal slow waves, however, each score of HAMD in patients with temporal slow waves showed a significantly lower score for "feeling of guilt" (P<0.01) and a significantly higher score for "general somatic symptoms" (P<0.01) and "hypochondriasis" (P<0.01).

CONCLUSIONS

Our EEG study suggested that temporal slow waves, which were probably associated with subtle cerebrovascular lesions, might reflect vulnerability to late-onset depression. In addition, depressed patients with temporal slow waves could be classified as a subgroup of heterogeneous late-onset depression based on the clinical findings. These results must be interpreted within the limitations of the sample selection procedure.

Co-occurrence of mucoepidermoid carcinoma and squamous cell carcinoma of the esophagus: report of a case

A case of co-occurrence of a mucoepidermoid carcinoma (MEC) and a squamous cell carcinoma (SCC) in the esophagus is described. The present patient was a 61-year-old man who underwent a curative esophagectomy with a regional lymph node dissection for a MEC in the lower esophagus and a SCC near the esophagogastric junction. The two lesions were endoscopically and histologically divided by a normal esophageal mucosa. The MEC of the esophagus consisted of SCC cells and signet-ring cells, and a mucin product and carcinoembryonic antigen, which were found at high levels in the blood serum before surgery, were detected histochemically in the signet-ring cells. The follow-up survey of the patients with esophageal MEC previously reported in Japan showed that most of the patients died of either local recurrence or widespread metastasis after treatment; the overall 5-year survival rate was 24.4% in the total 25 cases, and 27.7% in the 22 resected cases. However, 6 patients who died of therapeutic complications were included among these patients; furthermore, the 5-year survival rate after surgery was 29.2% in the patients treated over the last decade (1989-1998). We expect that the clinical outcome of patients treated for esophageal MEC will therefore improve in the future.

Decreased expression of the mRNA for somatostatin in the periventricular nucleus of depression-model rats

Expression of the mRNA for somatostatin (SRIF) in the periventricular nucleus (PeN), the level of SRIF in the stalk-median eminence (SME) and the concentration of growth hormone (GH) in the plasma were examined in depression-model rats in an attempt to confirm the hypothesis that SRIF neurons in the hypothalamus are hypofunctional in this model. We exposed male Wistar rats to intermittent walking stress for two weeks and then we measured their spontaneous running activity for 12 days. We divided the rats into a depression-model group and a partial-recovery group according to the spontaneous running activity of each rat after the termination of exposure to stress. Expression of SRIF mRNA in the PeN of the hypothalamus was monitored by in situ hybridization and relative levels were determined with an image analysis system. The relative level of expression of SRIF mRNA in the PeN was lower in rats in the depression-model group than in the control group and the partial-recovery group. The level of SRIF in the SME was lower and the plasma concentration of GH was higher in the depression-model group than in the other groups. Our findings suggest that reduced expression of mRNA for SRIF in the PeN might be associated with the pathophysiology of rats with this particular model of depression.

Increased expression of magnocellular arginine vasopressin mRNA in paraventricular nucleus of stress-induced depression-model rats

Exposure of rats to long-term intermittent walking stress results in a persistent inactive behavior in the subsequent two weeks in about 50% of rats (depression-model rats) while the activity returns gradually toward baseline in other rats (spontaneous recovery rats). To explore the role of hypothalamic-pituitary-adrenal (HPA) axis in these depression-model rats, we examined changes in the gene expression of corticotropin-releasing factor (CRF) and arginine vasopressin (AVP) in the paraventricular nucleus (PVN) of the hypothalamus using in situ hybridization histochemistry. We imposed the intermittent walking stress for two weeks in male Wistar rats, then compared the response of the depression-model rats and spontaneous recovery rats. The expression of CRF mRNA in PVN increased significantly by 60% and 80% compared to controls, in the model and the recovery rats, respectively. The magnocellular AVP mRNA in PVN increased significantly in the model rats by 60% compared to controls. The concentration of plasma ACTH increased in the model rats, but no significant change in plasma corticosterone or AVP level was noted in all three groups. Our results suggest that increased magnocellular AVP in PVN plays an important role in the regulation of HPA axis of the depression-model rats induced by long-term walking stress.

Enhanced response of growth hormone to growth hormone-releasing hormone and a decreased content of hypothalamic somatostatin in a stress-induced rat model of depression

This study was designed to evaluate changes in the hypothalamic somatostatin-growth hormone axis (SRIF-GH axis) in a stress-induced rat model of depression. We exposed male Wistar rats to intermittent walking stress for two weeks, and then measured their spontaneous running activities for 12 days. We divided the rats into the depression-model group and the partial recovery group according to their spontaneous running activities after the termination of exposure to stress. We examined the secretion of GH from the anterior pituitary by injecting human GH-releasing hormone (hGHRH) with intracardiac cannulae or by applying hGHRH or SRIF to isolated anterior pituitaries using a perifusion system. We also determined SRIF content in the stalk-median eminence (SME) and the plasma concentration of GH. In the depression-model group, intracardiac administration of hGHRH caused the enhanced release of GH into plasma, while application of hGHRH or SRIF to the anterior pituitary in vitro had similar effects on GH release in the control and partial recovery groups. Furthermore, the SRIF content was decreased in the SME and the GH concentration was increased in plasma. The partial recovery group gave similar values to the control group. The enhanced response of GH to hGHRH in the depression-model group might have been caused by the reduced content of SRIF in the SME in view of the unchanged response of GH to the infusion of hGHRH or SRIF in the perifusion system.

Effect of reserpine on 3-methoxy-4-hydroxyphenylethyleneglycol and 3,4-dihydroxyphenylacetic acid in the hippocampus of depression-model rats: an in vivo microdialysis study

Using in vivo microdialysis, we examined the effect of intraperitoneal injection of reserpine (2 mg/kg) on hippocampal 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) and 3,4-dihydroxy-phenylacetic acid (DOPAC), two major metabolites of catecholamine. Responses were examined serially for 12 h in the hippocampus of walking-stress-induced depression-model rats, recovery rats and control rats. Control rats showed a rapid rise followed by a gradual fall of free and total MHPG and a delayed increase of DOPAC in response to reserpine. Depression-model rats showed a significantly blunted biphasic response of free and total MHPG as well as blunted monophasic response of DOPAC compared with control rats. Recovery rats also exhibited a blunted fall response of MHPG. Our findings suggest that the vesicle membrane in the central noradrenaline (NA) neurons could be hyposensitive to reserpine in the depression-model rats.

Why is cyclooxygenase-2 expressed in neuroendocrine cells of the human alimentary tract?

During immunohistochemical studies of cyclooxygenase-2 (COX-2) on human colon cancers, many strong COX-2-immunoreactive cells scattered in the bottom of the crypt of normal colon mucosa were unexpectedly noticed. COX-2-immunoreactive cells were morphologically very similar to neuroendocrine cells and were confirmed immunohistochemically to be positive for chromogranin A or serotonin. Moreover, COX-2-immunoreactive neuroendocrine cells were observed not only in the large intestine, but also in the stomach, duodenum and small intestine. The role of COX-2 expression in neuroendocrine cells of the human alimentary tract was speculated.

Impaired endothelial function in epicardial coronary arteries after Kawasaki disease

BACKGROUND

Intimal lesions observed in the coronary arteries (CAs) of patients who have suffered episodes of Kawasaki disease (KD) raise concern about the premature development of arteriosclerosis. Accordingly, we investigated endothelial function in the epicardial and resistance CAs after KD during long-term observation.

METHODS AND RESULTS

We assessed the responses of left epicardial and resistance CAs to serial intracoronary infusions of acetylcholine (final concentrations, 0.1 and 1 micromol/L) and nitroglycerin in subjects by using quantitative angiography and a Doppler flow wire system. Three age-matched groups were evaluated: 8 control subjects (group 1), 10 KD patients with normal left CA from the onset (group 2), and 8 KD patients with a persistent or regressed aneurysm in the left anterior descending CA (LAD) (group 3). Acetylcholine (1 micromol/L) changed the LAD area to 114.0+/-2.6%, 72.7+/-3.9% (P<.05 versus group 1), and 88.9+/-4.3% (P<.05 versus groups 1 and 2) of baseline in groups 1, 2, and 3, respectively, with a similar degree of increased coronary blood flow in each group. Nitroglycerin increased the LAD area to 143.5+/-7.7%, 132.3+/-1.9%, and 120.8+/-5.6% (P<.05 versus group 1), respectively.

CONCLUSIONS

Results demonstrate a persistent endothelial dysfunction in the epicardial but not resistance CAs in patients after KD and enhanced stiffness of persistent or regressed aneurysms. The concern over early arteriosclerosis warrants the surveillance of KD patients from childhood to adulthood.

Optical bus interconnection system using Selfoc lenses

A novel optical bus interconnection system that uses Selfoc lenses is proposed. The technique can be categorized as one of free-space interconnects, and it has the potential to overcome the problems associated with the free-space optical system, such as difficulties of achieving precise assembling, compact mounting, and high durability. Its concept, fabrication techniques, features, and possible applications are discussed, along with an experimental result.

Multiple imaging and multiple Fourier transformation using planar microlens arrays

A new type of multiple imaging and multiple Fourier transformation system under coherent illumination using microlens arrays has been developed. The optical system is based on geometrical optics instead of convolution or diffraction. As a result, it has the advantage of design flexibility especially in alignment of the duplicate images. The experimental results of the system, which are implemented using planar microlens arrays fabricated by an ion exchange technique, are also discussed.

High numerical aperture planar microlens with swelled structure

The planar microlens is a 2-D integrated microlens fabricated by the selective ion exchange technique. This paper demonstrates a new class of planar microlens which has a high numerical aperture. The new planar microlens uses a swelling structure and index distribution which comes from replacing ions with different ion volumes. Lens diameters from 10 to 400 microm can be fabricated. A numerical aperture larger than 0.5 is achieved when the lens diameter is smaller than 100 microm. Use of this microlens in light coupling between an LD and a single-mode fiber is also evaluated.

[Relation between articulatory function and prosthesis. I-1. Longitudinal changing aspects in the duration of speech sound, muscular discharge of facial muscle and tongue pressure before pronunciation caused by the experimental palatal plate]

The author noticed the relation between articulatory functions and the prosthesis. For the purpose of clarifying the influence of the insertion of denture on the duration of speech sound and the articulatory functions before pronunciation and on the self-compensation of these organs. The experimental palatal plates were inserted on 13 subjects with natural dentition, assuming that they were inserted with complete denture, and the duration of speech sound, muscular discharge of facial muscle and tongue pressure before pronunciation were evaluated longitudinally with the pre-insertion of palatal plate as basis. As the result of this study, the following conclusions were obtained. The results of this study suggest that speech sound, lips and tongue being important organs as the articulators are placed under strong influence before pronunciation by insertion of the denture, whereas on the self-compensation of the articulators before pronunciation differed according to the point of articulation and the manner of articulation of each speech sound. Therefore, it was necessary to take care on the relation between the shape of palatal plate and the articulatory functions of lips and tongue in the clinical prosthodontics.

Optical implementation of an associative neural network model with a stochastic process

An optical associative neural network with a stochastic thresholding procedure has been demonstrated. The use of stochastic processing drastically improved the convergence rate into the correct global minima (recognition rate). The properties of undesirable spurious minima were also investigated. It was found that the spurious minima were represented as the mixed states of the stored vectors. A useful method to estimate the required noise level to vanish the spurious minima is described.

Effect of reflections on the drift characteristics of a fiber-optic passive ring-resonator gyro

We show the effect of reflections at the fiber ends on the drift characteristics of a fiber-optic passive ring-resonator gyro. A rotation-detection sensitivity as low as 3 x 10(-5) rad/sec (tau = 30 sec) was obtained by reducing the effect of reflected lights with an optical phase modulator.

Fiber-optic passive ring-resonator gyroscope using an external-cavity laser diode

We report a fiber-optic passive ring-resonator gyroscope that uses an external-cavity laser diode. The external-cavity laser diode is useful as the light source for the gyroscope if an appropriate cavity length is chosen. A rotation detection sensitivity of 10(-2) rad/sec was obtained with an integration time of 10 sec.

Evidence for the presence of a novel biosynthetic pathway for norspermidine in Vibrio

Enzymatic studies of the cell extracts of Vibrio alginolyticus and V. parahaemolyticus provided evidence that there exists a novel biosynthetic pathway for norspermidine (NH2(CH2)3NH(CH2)3NH2), a major polyamine species. In this pathway, the Schiff base formed between aspartic beta-semialdehyde and 1,3-diaminopropane is first reduced by a NADPH-dependent enzyme to yield "carboxynorspermidine" (NH2(CH2)3NH(CH2)2CH(NH2)COOH), which is in turn decarboxylated by a pyridoxal phosphate dependent enzyme to form norspermidine. The end product and its intermediate were identified by gas chromatography - mass spectrometry. Experiments with L-[U-14C]aspartic acid resulted in appreciable incorporation of the label into norspermidine. Putrescine could replace 1,3-diaminopropane as a substrate to produce spermidine, but at a reduced rate. The enzyme activity was greatly enhanced by dithiothreitol. Since the activity of an aminopropyltransferase that utilizes decarboxylated S-adenosylmethionine as an aminopropyl group donor could not be detected in any of the cell extracts by our assay method, it was concluded that this novel pathway is primarily responsible for producing norspermidine and spermidine in these species.

Cysteine protease inhibitors isolated from human malignant melanoma tissue

Cysteine protease inhibitors that specifically reacted with several cysteine proteases were found in KSCN extract of human melanoma tissue. From 30 gm of the tissue, approximately 593.5 U inhibitor was obtained. The inhibitors were adsorbed on a papain-Sepharose column and could be eluted with 10 mmol/L phosphate buffer, pH 6.0, containing NaCl or KCl, or with 20 mmol/L acetate buffer, pH 4.0, containing KSCN. They revealed a strong inhibitory activity for cysteine proteases such as ficin, papain, and cathepsin B, but did not react with cysteine protease bromelain or serine protease trypsin. No immunologic relationship was confirmed between the inhibitor and other well-known plasma inhibitors such as alpha 1-antitrypsin, alpha 2-macroglobulin, alpha 1-antichymotrypsin, antithrombin III, C1-in-activator, and alpha 2-plasmin inhibitor. With Sephadex G-100, two main peaks of molecular weight 40,000 and 10,000 were detected in the KSCN extract of the human melanoma tissue. However, the inhibitors revealed three molecular weights of 10,000, 25,000, and 80,000 when estimated by Sephadex G-100 gel filtration after papain-Sepharose affinity chromatography. On the other hand, the molecular weights of the inhibitors changed to two peaks of 25,000 and 10,000 on rechromatography with a papain-Sepharose column.

Studies on the role of polymorphonuclear leukocyte granule elastase in Arthus reaction

In the present study, attempts were made to clarify the role of an elastase-like enzyme in Arthus reaction by using rabbit-peritoneal polymorphonuclear leukocytes (PMNs). It was first confirmed that the injection of large amounts of PMNs with antibody can increase tissue damage in reversed Arthus reaction. The five various fractions, which were intact PMNs, whole homogenate, granule fraction, nuclei and cell debris, and membrane extract, were prepared from rabbit-peritoneal exudate. Each fraction was intracutaneously injected into the abdominal wall of rabbit. It was of particular interest that the tissue damage induced by membrane extract occurred earlier and was more severe than that caused by the others. Furthermore, membrane extract possessed remarkably higher caseinolytic and elastinolytic activities than the others. The membrane extract was partially purified by Sephadex G-100 column chromatography. The protein concentration of the elastase-like enzyme solution was 3.64 mg/ml, and its specific activity was 195 caseinolytic units and 0.45 elastinolytic units per milligram of protein. The cutaneous reaction by membrane extract was dependent on the concentration of this elastase-like enzyme and could be strongly inhibited by Elastatinal. From these results, the authors suggest that an elastase-like enzyme which originates in PMN granules is the key enzyme that promotes the severity of tissue damage in Arthus reaction.

Laser Doppler velocimeter with a novel optical fiber probe

A practical laser Doppler velocimeter with optical fibers in the whole system was developed. The novel optical probe designed for this LDV is constructed of a graded-index rod lens attached to the end of an optical fiber. Since the laser beam from the probe is well collimated, the velocity accuracy and sensitivity are significantly improved. Mechanical vibration measurements were also carried out with this LDV; vibration amplitude down to 1.0 microm p-p can be measured at a frequency of 120 Hz with high accuracy.